Federal Court of Australia

Hanwha Solutions Corporation v REC Solar Pte Ltd [2023] FCA 1017

ORDERS

THE COURT ORDERS THAT:

1.    The parties confer and supply to the chambers of Justice Burley by 4pm on 19 September 2023 draft short minutes of order giving effect to these reasons and a proposed timetable for further steps to be taken in the proceedings.

2.    Insofar as the parties are unable to agree to the terms of the draft short minutes of order referred to in order 1, the areas of disagreement should be set out in mark-up.

3.    The confidential reasons for judgment be published only to those persons who have executed suitable confidentiality agreements as determined in first instance by the solicitors acting for the applicants and the respondents.

4.    The non-confidential reasons, which do not include the reasons concerning patent infringement, are published without restriction.

Note:    Entry of orders is dealt with in Rule 39.32 of the Federal Court Rules 2011.

CONFIDENTIAL REASONS FOR JUDGMENT

BURLEY J

1.    INTRODUCTION

1.1    The parties and the proceedings

1    These proceedings concern solar cell technology, a claim of patent infringement, a cross claim for the invalidity of the asserted claims of the patent, misleading and deceptive conduct and the making of unjustified threats of patent infringement.

2    Hanwha Solutions Corporation, a company incorporated in South Korea, is the registered proprietor of Australian patent No AU 2008323025, which is entitled “Method for manufacturing a solar cell with a surface-passivating dielectric double layer, and corresponding solar cell”. It and Hanwha Q CELLS Australia Pty Ltd (collectively Hanwha) are the applicants. The patent has a priority date of 14 November 2007.

3    Hanwha initially commenced three sets of proceedings being:

(a)    NSD 394 of 2019 against LONGi Green Energy Technology Co Ltd, a company organised under the laws of the Peoples Republic of China, and three other related companies (collectively, LONGi).

(b)    NSD 395 of 2019 against Jinko Solar Australia Holdings Co Pty Ltd; and

(c)    NSD 458 of 2019, against REC Solar Pte Ltd, a company organised under the laws of Singapore and two other companies that REC Solar has authorised to sell products that Hanwha alleges fall within the scope of the claims of the patents, being Sol Distribution Pty Ltd and Baywa r.e. Solar Systems Pty Ltd. For convenience, I refer to these respondents collectively as REC Solar.

4    As matters transpired, after the hearing, but before judgment, the proceedings in (a) and (b) settled. As I explain in section 1.5 below, each of LONGi, Jinko and REC Solar co-operated in the conduct of the proceedings so that there was no unnecessary duplication in their approach to the invalidity case. The consequence was that, leaving aside the separate allegations of infringement against LONGi and Jinko, the content of the matters in controversy remained largely unchanged as a result of the settlements.

1.2    The case asserted by Hanwha

5    In its seventh amended statement of claim, Hanwha alleges that multiple products sold and offered for sale by or with the approval of REC Solar (REC Solar products) fall within the scope of asserted claims 12, 13, 14, 16, 17, 18, 19 and 21 of the patent. Hanwha also alleges that by reason of its infringing conduct REC Solar has falsely represented that one or more of the accused REC Solar products do not infringe any intellectual property rights and that it is legally entitled to sell and third parties are entitled to purchase, install and use those products in breach of the Australian Consumer Law being schedule 2 to the Competition and Consumer Act 2010 (Cth) (ACL claim).

6    REC Solar denies that the REC Solar products fall within the scope of the asserted claims and also advances a cross claim alleging that those claims are not valid.

1.3    The responsive case advanced by REC Solar

7    In its fourth amended particulars of invalidity REC Solar relies on lack of novelty, lack of inventive step, lack of fair basis, inutility and lack of clarity as grounds. It also contends that Hanwha made unjustified threats of patent infringement, in breach of s 128 of the Patents Act 1990 (Cth). I note that the version of the Patents Act applicable to the proceedings is that following the amendments made by the Patents Amendment Act 2000 (Cth) but before those made by the Intellectual Property Laws Amendment (Raising the Bar) Act 2012 (Cth) (RTB Act).

8    In its Amended Consolidated Particulars of Invalidity (POI), REC Solar sets out the grounds upon which it contends that claims 9, 11-14 and 16-21 (challenged claims) ought to be revoked.

9    In its novelty challenge as advanced in its closing submissions, REC Solar contends that, by reason of the publication of the documents identified below, the claims identified are not novel in accordance with s 18(1)(b)(i) of the Act (grounds 1, 2 and 3):

(a)    International Patent Application WO 2008/065918 A1 entitled “Solar cell and method of manufacturing the same” (Isaka) is said to invalidate claims 9, 11-14, 17-19 and 21 of the patent;

(b)    US patent application 2006/0102972 A1 entitled “Optoelectronic devices, solar cells, method of making optoelectronic devices, and methods of making solar cells” (Bhattacharyya), published 18 May 2006, is said to invalidate claims 9 and 11 of the patent; and

(c)    US patent 4,463,216 entitled “Solar Cell” (Nakano), published 31 July 1984, is said to invalidate claims 9, 12, 16 and 21 of the patent.

10    In its lack of inventive step challenge, REC Solar contends that the invention in the challenged claims is not patentable for want of an inventive step within the meaning of s 18(1)(b)(ii) of the Act by reason that a person skilled in the art in light of the common general knowledge before 14 November 2007 together with the following documents considered separately or together (ground 4):

(a)    An article entitled “Ultralow surface recombination of c-Si substrates passivated by plasma-assisted atomic layer deposited Al2O3” by B. Hoex et al (Hoex 2006); and

(b)    An article entitled “Excellent passivation of highly doped p-type Si surfaces by the negative-charge-dielectric Al2O3” by B. Hoex et al (Hoex 2007)

would find the invention to be obvious.

11    In relation to its challenge on the basis of lack of fair basis, REC Solar advances six contentions.

12    First, it contends that the challenged claims travel beyond the matter described in the specification in that there is no real and reasonably clear disclosure in the specification of a solar cell, or a method for manufacturing such a solar cell, having a first dielectric layer formed by means other than atomic layer deposition (ALD) (ground 5).

13    Secondly, it contends that if claim 9 is construed such that the “silicon substrate” may have a silicon oxide layer on its surface, then the specification does not comply with s 40(3) of the Act in that claim 9 and claims 11-14 and 16-21 when dependent on claim 9 are not fairly based on the specification (ground 6).

14    Thirdly, it contends that if the challenged claims encompass a solar cell or method of making such a cell with material other than aluminium oxide on a surface of the silicon substrate, those claims travel beyond the matter described in the specification (ground 7).

15    Fourthly, if claim 9 is construed such that it encompasses a solar cell which is not manufactured by a method which includes depositing a first dielectric layer comprising aluminium oxide on a surface of the silicon substrate, then claim 9 and claims 11-14 and 16-21 when dependent on claim 9 travel beyond the matter described in the specification (ground 8).

16    Fifthly, each of claims 9, 11-14, 16 and 21 travel beyond the matter described in the specification in that:

(a)    Insofar as it includes a silicon substrate having a lightly doped region of conduction type n it includes a solar cell or a method of manufacturing a solar cell in which an inversion layer is induced below the passivating layer, and in which a parasitic shunt may form; and

(b)    There is no real and reasonably clear disclosure of such a solar cell or method of manufacturing such a cell.

(ground 9)

17    Sixthly, each of the challenged claims travels beyond the matter described in the specification as the specification discloses a second dielectric layer with a high hydrogen content (of at least 1 atomic percent (at. %) preferably at least 2 at. % and more preferably at least 5 at. %) and each of those claims are not so limited (ground 10).

18    In ground 12, REC Solar contends that the alleged invention as claimed in the challenged claims is not a patentable invention for the purposes of s 18(1)(c) of the Patents Act for lack of utility in that those claims include solar cells containing dielectric layers that do not achieve the promise of the invention.

19    REC Solar contends that the specification of the patent does not comply with the requirements of s 40(3) of the Patents Act in that claims 16, and claims 17-21 to the extent that they are dependent on claim 16, are not clear and succinct because:

(a)    In ground 20, the phrase “wherein the surface of the silicon substrate is passivated by hydrogen” is unclear and ambiguous and there is no workable standard for determining whether that feature is present;

(b)    In ground 20A, if the phrase “hydrogen being embedded into the second dielectric layer” in claim 9 is construed so as to require a minimum concentration of hydrogen, then it is ambiguous because there is no workable standard for determining whether the feature is present.

20    For completeness, I note that grounds 11 and 13-19 of the POI were not pressed by REC Solar in closing submissions.

1.4    Summary of conclusions

21    For the reasons set out in this judgment I have found that the REC Solar products do not fall within the scope of claim 9 of the patent, and accordingly none of the asserted claims are infringed because each of the asserted claims is dependent upon claim 9. As a result, the ACL claim advanced by Hanwha, which depended on a finding of infringement, also fails. The unjustified threats claim advanced by REC Solar succeeds.

22    I also find that claims 9, 12, 16 and 21 are invalid for want of novelty in the light of Nakano but that otherwise the invalidity challenges advanced by REC Solar fail.

23    REC Solar has asserted confidentiality over much of the information concerning the make-up of the REC Solar products. Accordingly, I will not publish the infringement section of these reasons until the parties have had an opportunity to consider whether an agreed (redacted) version of that section can be released. The only orders that I will make are for the parties to confer and supply to my chambers within 21 days draft short minutes of order giving effect to these reasons, and a proposed timetable for further steps to be taken in the proceedings.

1.5    Relevant aspects of case management of the three proceedings

24    The proceedings were complicated and hard-fought. Prior to the settlements reached between Hanwha, LONGi and Jinko, the management of the case involved dealing with three sets of allegations of infringement concerning multiple products manufactured by each of the three sets of respondents. All parties are fierce competitors in the emerging field of solar cell production. Each maintained a high degree of confidentiality in their products and processes of manufacture.

25    The conduct of the proceedings is a testament to the good sense of the parties and the professionalism of their advisors. In all three of the cases, the parties consented to (or did not inordinately oppose) a number of significant case management steps that enabled the proceedings to be managed together and conducted efficiently.

26    The following aspects of the management of the case warrant mention:

(1)    Early in the proceedings the respondents accepted that they should be permitted one substantive witness to give evidence going to questions of invalidity. This considerably eased the progress of the trial and eliminated unnecessary duplication. The invalidity expert retained by the respondents was Professor Weber, to whom I refer below.

(2)    Before the preparation of evidence in chief, REC Solar, LONGi and Jinko each filed and served a Product Description of the products alleged to be infringed and a position statement of non-infringement concerning each of the impugned products. Hanwha responded with a position statement on infringement that identified any factual or legal matters in dispute arising from the respondents’ position statement.

(3)    A technical primer was prepared using a process whereby, when Hanwha served its expert affidavit evidence in chief on infringement, it identified a portion that included what was intended to be an uncontroversial introduction to the relevant technology and a glossary of relevant terms at the priority date. In their expert affidavit evidence in chief on validity, the respondents identified what was also intended to be an uncontroversial portion of that affidavit that included a summary of the relevant common general knowledge to the skilled addressee before the priority date. Each side’s expert responded to these sections and then the parties jointly served and filed the primer and statement of common general knowledge, which included a mark-up indicating any areas of disagreement between them.

(4)    Although each of the respondents pleaded separate particulars of invalidity, shortly before the trial they cooperated to produce one consolidated set of particulars of invalidity, thereby limiting unnecessary repetition.

(5)    The parties agreed to suitable confidentiality regimes during the preparation of the proceedings to ensure that, whilst their confidential manufacturing processes were protected, sufficient disclosure was provided to the other parties to enable the legal advisors to understand how the case would run. This involved a complicated regime with multiple levels of confidentiality that required ongoing cooperation between the parties and minimal involvement by the Court.

(6)    Orders were made that all issues of liability, including as to infringement, contravention of the ACL and unjustified threats under s 128 of the Patents Act, were to be determined separately and before any issues of election and quantification of pecuniary relief (including any additional damages).

(7)    The respondents had divergent interests on the question of infringement. Whilst they relied on the evidence of Professor Weber in support of their grounds of invalidity, each relied upon the evidence of separate experts in support of the non-infringement defences (being Dr Glew (REC Solar), Dr Ruby (Jinko) and Professor Weber (LONGi)).

(8)    Those experts who were involved in giving evidence concerning infringement issues, but who were not involved in giving evidence concerning the validity of the patent, were not invited to participate in the preparation of joint expert reports concerning validity, or the subsequent concurrent evidence sessions addressing that topic.

(9)    The experts, with the assistance of a Judicial Registrar of the Court, participated in meetings prior to the hearing and produced six separate joint expert reports (JER), three concerning infringement issues (REC Solar, Jinko and LONGi JER respectively), one concerning claim construction (Construction JER) and two concerning invalidity issues (Validity JER).

(10)    The oral and written evidence of the experts in all three proceedings given by Professor Weber, Dr Glew, Dr Ruby, Dr Rentsch, Professor Cuevas-Fernandez and Dr Winderbaum, including the JER, was taken as evidence in all of the proceedings.

(11)    One issue arose during the course of objections to evidence, when Hanwha expressed concern that the infringement experts, in giving evidence going to construction, might be considered also to have given expert evidence relevant to the questions of fair basis and inutility of the patent. Those concerns did not arise out of any improper instructions to the experts, but rather because, naturally enough, it was necessary for each expert to construe the claims in the context of the specification as a whole, which led them to express views as to the breadth of the claims in the context of the invention disclosed as a whole. To ensure that the experts maintained the roles envisaged for them early in the proceedings, and bearing in mind that Professor Weber had separately given evidence concerning all invalidity issues, particular paragraphs identified by Hanwha were made the subject to a limitation under s 136 of the Evidence Act 1995 (Cth) to the effect that those paragraphs may not be relied upon for the purposes of the fair basis or utility challenges (as the case may be) to the validity of the patent.

2.    THE LAY WITNESSES

2.1    Hanwha – the REC Solar U Cell

27    Magnus Garbrecht is a Senior Transmission Electron Microscopy (TEM) Manager at Sydney Microscopy & Microanalysis at the University of Sydney, specialising in aberration-corrected high-resolution TEM imaging and spectroscopy techniques in the field of materials science. He has a Diploma in Physics and a PhD in Materials Science from the Institute for Experimental and Applied Physics, Christian-Albrechts-University in Kiel, Germany. Dr Garbrecht gives evidence about TEM analysis he and Ms Pillai (see below) undertook on a sample of the REC Solar product identified as the U Cell. He was not cross-examined.

28    Ashalatha Indiradevi Kamalasanan Pillai is a Scanning Electron Microscopy (SEM) Specialist at Sydney Microscopy & Microanalysis at the University of Sydney. In this role, she provides technical support in SEM and Focused Ion Beam (FIB) techniques. Ms Pillai gives evidence about TEM analysis she and Dr Garbrecht undertook on a sample of the U Cell that was prepared by the use of a FIB. She was not cross-examined.

29    Mohanad Mursi is a Manager at the Centre for Advanced Structural Engineering in the School of Civil Engineering at the University of Sydney. He holds a PhD in Civil Engineering and a second PhD in Structural Engineering from the University of New South Wales. Dr Mursi gives evidence about work undertaken by himself and his colleagues at the Centre for Advanced Structural Engineering in relation to extracting samples of U Cells from the U solar modules for subsequent testing. He was not cross-examined.

2.2    REC Solar

30    Udit Sharma is a scientific fellow at Eurofins EAG Materials Science. In this role, he facilitates, manages, oversees and reports upon the testing and analysis of a range of industrial materials including in the field of solar cell technology. Mr Sharma gives evidence regarding testing undertaken by EAG of the Sing, Vina, MS, MMS and MV Cells. Mr Sharma was not cross-examined.

31    Jae Sung Lee, is an R&D researcher employed by REC Solar in the Cell R&D Department. In this role he is responsible for researching and developing new technology, including in the field of solar cells, and testing and analysing solar cells, including engaging external service providers to undertake testing and analysis of REC Solar products. Mr Lee gives evidence regarding testing undertaken by WinTech Nano-Technology Services Pte Ltd of the NSP and Solartec Cells. He was not cross-examined.

32    Shankar Gauri Sridhara is the Chief Technology Officer employed by REC Solar. Prior to this position, he joined the REC Scan Module AB division of REC in Sweden, joined the Singapore division of REC as a director of module technology in 2011, and assumed responsibility for the entirety of research and development in REC from poly-silicon to products in 2016. Dr Sridhara was responsible for preparing:

(1)    REC Solar’s product description (REC-PD), which involves his interpretation of testing undertaken by WinTech of the Sing, Vina, NSP and Solartec Cells; and

(2)    REC Solar’s second supplementary product description (REC-SSPD), which involves his interpretation of testing undertaken by WinTech of the MS and MMS Cells and his interpretation of testing undertaken by EAG of the MV Cell.

33    Dr Sridhara verifies the REC-PD and REC-SSPD relied upon by REC Solar in these proceedings, and gives evidence providing the primary sources and contemporaneous documents referred to and relied upon in the REC-PD and REC-SSPD. Dr Sridhara was cross-examined.

34    John Lee is a partner at Gilbert + Tobin, the solicitors acting for REC Solar. He gives evidence annexing correspondence relevant to REC Solar’s unjustified threats cross-claim. He was not cross-examined.

3.    THE EXPERT EVIDENCE

3.1    Hanwha

35    Jochen Rentsch is Department Head, PV Production Technologies – Surfaces and Interfaces, at the Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany. He has previously provided expert evidence in relation to patent infringement proceedings in Germany between companies related to Hanwha on the one hand and companies related to the respondents on the other concerning a European patent No 2 220 689, which is related to the patent. In 2002 Dr Rentsch completed a degree in physics whereupon he began a PhD thesis entitled “Dry production technologies for crystalline silicon solar cells” at Albert-Ludwigs University in Frieburg. In 2005 he commenced working for his current employer focussing on research in solar cell and photovoltaics production technologies and in particular upon deposition and etching processes and technologies.

36    Dr Rentsch has given six affidavits in these proceedings which address questions of infringement and validity of the patent (excluding lack of inventive step). He participated in the preparation of the Construction JER and infringement JERs for each of the LONGi, Jinko and REC Solar infringement cases and the matching concurrent evidence sessions for each.

37    Andres Cuevas-Fernandez is an Emeritus Professor at the Australian National University (ANU). He has worked in the field of silicon solar cell technology since 1976. He received an undergraduate degree in telecommunications engineering at the Universidad Politecnica de Madrid in 1976 and conducted research in the area of silicon solar cells in the Laboratorio de Semiconductores to earn his PhD from the same university in 1980. He has since worked in various teaching and research positions. In July 1993 he moved to the ANU where he was the head of the School of Engineering from 2007 until 2010. He retired in April 2018 whereupon he took an appointment as Emeritus Professor.

38    In his affidavit Professor Cuevas-Fernandez describes himself as one of the most experienced researchers in the field of photovoltaics, having contributed to the scientific and technological advancement of silicon solar cells since 1976. He has collaborated extensively with many of the leading researchers and research institutes in the field and also with workers in industrial settings. He is a named inventor on 12 patents and patent applications. His research has almost entirely been devoted to wafer-based silicon solar cell technology.

39    Professor Cuevas-Fernandez gave one affidavit addressing the validity of the patent and participated in joint expert reports and concurrent evidence sessions concerning the alleged lack of inventive step in the patent.

40    Professor Cuevas-Fernandez participated in the preparation of the two Validity JERs concerning the obviousness case and the matching concurrent evidence sessions for each.

41    Saul Winderbaum is a retired adjunct associate professor at the University of New South Wales and Director of Shamash Australia Pty Ltd. From 1984 until 1993 he worked as a process engineer in the production of microelectronic components. In 1998 he was awarded a PhD for a thesis entitled “Optical enhancements in silicon solar cells” by the University of New South Wales. Prior to commencing work on his PhD thesis, Dr Winderbaum had used Plasma-Enhanced Chemical Vapour Deposition (PECVD) extensively in microelectronics to deposit silicon nitride layers. He developed this use of PECVD in depositing silicon nitride on silicon wafers in the context of solar cells in his PhD research. In 2000 he took a position as senior scientist at BP Solar where he was responsible for modifying their manufacturing processes to establish the use of silicon nitride deposited by PECVD as an anti-reflective coating. In 2003 Dr Winderbaum became a consultant to BP and other companies in the solar cell industry.

42    Dr Winderbaum participated in the preparation of one Validity JER relating to the question of inventive step and the equivalent concurrent evidence session.

3.2    REC Solar

43    Klaus Weber is a Professor in the School of Engineering at the ANU. He was awarded a Bachelor of Electrical Engineering from the University of Adelaide in 1992 and a PhD in Engineering for a thesis entitled “Liquid phase epitaxy of silicon for thin film silicon solar cells” from the ANU in 1997. His research focussed on producing silicon films of 0.01 to 0.08 mm thickness to evaluate and demonstrate the potential of such films for use in low cost, high efficiency silicon solar cells.

44    From 1998 until 2014 he conducted research at the ANU. During his time as a post-doctoral fellow at ANU, he worked in collaboration with Boral Energy (later called Origin Energy) on a technique that he had assisted in developing (called “epilift”) to detach thin silicon films from the substrate on which they were formed. He continued this research from 1998 until 2001, which included trying to scale it up for industrial use. Also in collaboration with Origin Energy, from 2000 to 2001 Professor Weber assisted in the development of a new technology for the fabrication of thin silicon solar cells which became the subject of several patents. From 2002 to 2014 Professor Weber continued to work on developing this technology. From 2001 to 2007 Professor Weber was also involved in researching various properties of low pressure chemical vapour deposition (LPCVD) silicon nitride for use in solar cells.

45    Professor Weber has published over 140 papers and is a named inventor on 14 patents or patent applications, most of which pre-date the priority date. In his oral evidence he accepted that he was a leading figure in solar cell research who was doing original, cutting-edge research and who, when pressed, accepted that he was “moderately inventive”.

46    Professor Weber gave evidence relevant to the validity of the patent and the question of infringement in relation to the alleged infringement by the LONGi products. He participated in the preparation of the Construction JER, the LONGi infringement JER and the Validity JER and he gave concurrent evidence in sessions concerning these topics.

47    Alexander David Glew is a materials scientist and mechanical engineer. His academic credentials include a Bachelor of Science and a Masters of Science in Mechanical Engineering from the University of California, Berkeley received respectively in 1985 and 1987, a Master of Science in Materials Science and Engineering from Stanford University in 1995 and a PhD in Materials Science and Engineering from Stanford University in 2003. The subject of his doctoral dissertation related to PECVD of dielectric films.

48    Dr Glew worked from 1987 until 1997 for Applied Materials Inc, a company that manufactures the equipment used to make semiconductors and sells that equipment to companies who make semiconductors. He had various roles within the company, with particular emphasis on chemical vapour deposition, a process involving the mixing of two or more gasses in a process reactor or chamber and having them meet on the surface of a substrate to deposit a thin film which, in the semiconductor or solar industry, would be 2 to 3 nanometres (nm) or less. In 1997 he left Applied Materials and became the president of his own company, Glew Engineering, which provides consulting services to various technology or engineering areas, including chemical vapour deposition technology. He has assisted component suppliers and equipment suppliers on various projects including in relation to gas panel design, integrated circuits failures and semiconductor equipment failures. His company’s practice includes multi-physics finite element analysis.

49    In his first affidavits, Dr Glew was provided a review of the patent and was asked to consider whether the REC Solar Multi Sing, Multi Vina, NSP and Solartec Cells fall within claims 9, 11-14 and 16-21 of the patent and to respond to the evidence of Dr Rentsch. In his second affidavit he was asked to consider whether three additional solar cells, referred to as the MS, MMS and MV cells infringed those claims and respond to further evidence from Dr Rentsch. In his third affidavit, Dr Glew was asked to consider whether the U Cell fell within the claims and to respond to further evidence from Dr Rentsch. In his fourth affidavit, Dr Glew was provided with certain documents annexed to the affidavit of Mr Lee concerning testing performed by WinTech on the Solartec and NSP products.

50    Dr Glew participated in the preparation of the Construction JER and the REC Solar infringement JER.

51    Douglas Scott Ruby is a consultant in the photovoltaics industry. He studied physics in university and was awarded a Bachelor of Science from the Massachusetts Institute of Technology in 1978 and was awarded a Masters and PhD from the University of Illinois specialising in semiconductor physics in 1980 and 1985 respectively. After his PhD, he worked for Sandia National Laboratories as a researcher from 1985 until 2008 working in its photovoltaics solar cell research division where he focussed on devising methods and procedures which could be employed in solar cell manufacturing to make solar cells more efficient or less expensive to manufacture. In about 1999, Dr Ruby became the leader of his division’s photovoltaic cell development team, managing seven researchers including in work directed towards improving surface passivation and reducing surface reflectance.

52    In his first affidavit Dr Ruby gave his views as to the disclosure of the patent and the construction of the claims and expressed views concerning the alleged infringement of certain claims by the Jinko products (which are not relevant to the present proceedings). In his second affidavit he provided some clarification of a point made in his first affidavit.

53    Dr Ruby was involved in the preparation of the Construction JER and the Jinko infringement JER and gave concurrent evidence in sessions concerning those topics.

4.    THE AGREED COMMON GENERAL KNOWLEDGE

54    Annexure A to this judgment consists of parts of the primer and agreed common general knowledge document provided by the parties. It was prepared as a result of an iterative process. It arises from a combination of the evidence of Dr Rentsch and Professor Weber insofar as it provides an explanation of some relevant background concepts, and a combination of evidence of Professor Weber and Professor Cuevas-Fernandez insofar as it concerns matters going to common general knowledge relevant to the question of whether or not the invention claimed involves an inventive step. It has been edited to address more central aspects of the technology. To the extent that the parties did not agree on its content, Annexure A includes my findings as to the common general knowledge. It is recommended reading for those not familiar with the technology in the patent.

5.    THE PATENT

55    The patent relates to the production of a more efficient solar cell using a double dielectric layer stack that reduces recombination losses by increasing surface passivation. The specification is to be understood in the light of the common general knowledge of the persons skilled in the art, including the information set out in Annexure A.

5.1    The specification

56    The patent is entitled “Method for manufacturing a solar cell with a surface-passivating dielectric double layer, and corresponding solar cell” and the field of the invention is described in the same terms.

57    The Background of the Invention first provides a reference to the technology (page 1 line 20):

A key requirement for achieving high degrees of efficiency in solar cells is very effective suppression of surface recombination losses. For this purpose, the surface of solar cells should be passivated as effectively as possible, so that charge carrier pairs which are generated inside the solar cell by incident light and which diffuse to the surfaces of the solar cell substrate do not recombine at the solar cell surface, so that they would no longer be available to help improve the efficiency of the solar cell.

58    The Background then identifies four relevant approaches to the problem present in the prior art and difficulties said to arise from that art.

59    The first approach, which is said to arise in laboratory solar cells but not to be in general use in the industrial manufacture of solar cells, is the growing of silicon dioxide at a high temperature (greater than 900 °C). However, this not only adds expenditure in solar cell processing but also has a further difficulty in that high temperature oxidation can lead the more economical multicrystalline silicon to experience “a considerable reduction in material quality” in that the charge carrier lifetime is reduced and thus the wafter has losses in efficiency.

60    The second approach is referred to as a low-temperature alternative, which is surface passivation using amorphous silicon nitride or silicon carbide which can be prepared at temperatures of 300-400 °C by PECVD. The specification provides references to two publications, one by T. Lauinger et al, and another by I. Martin et al. It says that the dielectric layers produced in this way can be used only to a limited degree for large-area, high efficiency solar cells because they contain a high density of “pinholes”, being small holes or pores in the layer, so that they may not have good insulating properties. A further problem with this approach is said to be that (page 2 line 18):

… their passivating effect is based largely on a very high positive charge density within the dielectric layers that can lead, during the passivation of the back of the solar cell if a p-type silicon wafers are used, for example, to the formation of an inversion layer via which an additional leakage current of minority charge carriers can flow away from the base of the solar cell to the back contacts (what is known as a “parasitic shunt”). On highly doped p+ silicon surfaces, silicon nitride can even lead, on account of the high positive charge density, to depassivation compared to an unpassivated p+ surface.

61    The third approach is using amorphous silicon layers which can also be produced by PECVD at very low coating temperatures of typically greater than 250 °C. While very good surface passivation was achieved (page 3 lines 7-14):

… the surface-passivating property of amorphous silicon layers of this type may be very susceptible to temperature treatments. In current-day industrial solar cell processes, the metal coating is in many cases carried out by means of screen printing technology, the last process step typically being a firing of the contacts in a continuous infrared furnace at temperatures of between approx. 800 °C and 900 °C. Although the solar cell is exposed to these high temperatures only for a few seconds, this firing step can lead to considerable degradation of the passivating effect of the amorphous silicon layers.

62    The fourth approach is using aluminium oxide layers which are deposited by means of ALD at about 200 °C, for example, and then tempered at about 425 °C. Using this approach, whilst good passivating results are said to have been achieved, only a single molecular layer is generally deposited on the substrate surface within each deposition cycle.

63    As a deposition cycle typically lasts about 0.5 to 4 seconds (s), correspondingly low deposition rates are obtained. The deposition of aluminium oxide layers at a thickness which is suitable for use as an antireflection layer or as a back reflector therefore requires deposition durations which have in the past shown a use of such layers in industrially produced solar cells to be commercially disadvantageous.

64    The Summary of the Invention then observes that there may be a need for a solar cell and a method for manufacturing in which on the one hand, good passivation of the surface of the solar cell can be achieved and, on the other hand (page 4 lines 1-3):

… the above-mentioned drawbacks of conventional surface-passivating layers can be at least partially avoided. In particular, it should be possible to produce solar cells displaying very good surface passivation in an economical, industrially viable manner.

65    The specification describes a first aspect of the invention (page 4 line 6 to page 5 line 18):

According to a first aspect of the present invention, a method is proposed for manufacturing a silicon solar cell, including the following steps: providing a silicon substrate; depositing a first dielectric layer on a surface of the silicon substrate by means of atomic layer deposition, wherein the first dielectric layer comprises aluminium oxide; and depositing a second dielectric layer on a surface of the first dielectric layer, the materials of the first and the second dielectric layer differing and hydrogen being embedded into the second dielectric layer.

This first aspect of the present invention may be regarded as being based on the following idea: a method is specified for manufacturing silicon solar cells with a dielectric passivating layer for reducing surface recombination losses. The dielectric passivating layer is composed of two partial layers, of a very thin aluminium oxide-containing layer, which is formed by atomic layer deposition (ALD), and also of a thicker layer made of silicon oxide, silicon nitride or silicon carbide, for example, which can be deposited on the aluminium oxide layer by means of plasma enhanced chemical vapour deposition (PECVD), for example.

The dielectric double layer produced in the method according to the first aspect allows the passivation of both high and low-doped regions of the solar cell surface of conduction type p or n. It is possible to allow stable passivation which retains its passivating properties even after a firing step in the temperature range of 800-900 °C for burning-in of metal contacts. At the same time, the dielectric passivating layer can also have advantageous optical properties, i.e for application to the front of the solar cell, the layer can serve as an effective antireflection layer; during application to the back of the solar cell, the passivating layer can form, together with metal coating over the entire area of the back, an effective mirror for photons with energies close to the silicon band gap in order to improve what is known as “light trapping”, i.e. the trapping of light by multiple internal reflection, in the solar cell. Furthermore, the negative effect of “parasitic shunting”, which is known from silicon nitride, can be avoided for rear surface passivation on standard solar cell semiconductor material of conduction type p.

66    In a passage much emphasised by the parties, the specification continues (page 5 lines 10-16):

The key to understanding the outstanding passivating effect and tempering stability of the stack layer according to the invention may be identified in the combination of the Si/Al₂O₃ interface, which is ideally atomically flat and is produced as a matter of course during the ALD process, and the highly hydrogenous SiO_x, SiN_x or SiC_x layers, such as are formed during the PECVD process, for example. A part of the hydrogen from the PECVD-deposited layers can diffuse through the ultrathin Al2O3 layer and passivate unsaturated silicon bonds at the interface to the silicon.

(Emphasis added)

67    The reference above to the “Si/Al₂O₃ interface” is to the point of interaction between the previously described silicon wafer and the very thin aluminium oxide layer.

68    The specification then continues by describing features, details and possible advantages of embodiments of the manufacturing method. This commences by noting that the silicon substrate “may be a thin monocrystalline or multicrystalline silicon wafer or else a silicon thin wafer”. The specification notes that the front of the solar cell substrate that faces the incident light (sun) may be coated, in which case the second dielectric layer is applied preferably as an antireflection layer, which is at a thickness at which negative interferences occur for the incident and reflected light. This may be from about 50 to 150 nm in thickness. Alternatively, the back may be coated, in which case the second dielectric layer is embodied as a “back surface reflector” so that light which penetrates the entire solar cell is for the most part reflected at that surface and thus passes through the solar cell substrate a further time.

69    In a further passage that gave rise to considerable debate in submissions, the specification describes that the first dielectric layer may be applied by reference to three steps, first a cleaning of the silicon substrate (page 6 lines 6-12):

Before the depositing of the first dielectric layer, the surface of the silicon substrate can be thoroughly cleaned, so that no contamination remains thereon that might disturb the subsequently deposited dielectric layer. In particular, the surface of the silicon substrate can be slightly etched away, for example in a solution which on the one hand contains an oxidising agent and which on the other hand contains hydrofluoric acid (HF) which etches away the oxidised silicon oxide. A suitable cleaning method known in the production of solar cells is for example what is known as RCA cleaning.

70    The next step in one embodiment is the application of the aluminium containing layer (page 6 line 15 to page 7 line 4):

According to one embodiment of the method according to the invention, for the atomic layer deposition of the first dielectric layer, the silicon substrate is firstly flushed with an aluminium-containing compound comprising at least one of the components Al(CH₃)₃, AlCl₃, Al(CH₃)2Cl and (CH₃)2(C₂H₅)N:AlH₃, so that an aluminium-containing layer is deposited on the surface of the silicon substrate. Subsequently, the aluminium-containing layer is oxidised to higher valency in an oxygen-containing atmosphere.

During the flushing of the silicon substrate with the aluminium-containing compound, the aluminium-containing compound can cling to the silicon surface at the points at which it enters into contact with the silicon surface. A chemical reaction with the silicon surface can occur; this is also referred to as chemisorption. In the best of cases, this can lead to the formation of a monomolecular layer made up of molecules of the aluminium-containing compound. It may be advantageous in this regard that this molecular layer can be almost perfectly tight, i.e. on correct selection of the processing parameters, such as duration and temperature during flushing, the entire silicon surface is covered with molecules of the aluminium-containing compound. This allows the subsequently produced first dielectric layer to be substantially atomically or molecularly tight.

71    The third step is the oxidation of the aluminium containing oxide (page 7 lines 6-16):

In a subsequent processing step, the previously deposited molecular layer of the aluminium-containing compound is oxidised to higher valency. This can take place for example by flushing with oxygen or an oxygen-containing gas. In order to speed up the chemical reactions, the oxygen can be provided in the form of a high-energy O₂ plasma (plasma enhanced deposition) …

72    The specification provides that the process can be repeated several times in order to achieve a sufficient thickness of the aluminium oxide layer, with the entire sequential deposition process being carried out in a common chamber.

73    The specification then says (page 8 line 1):

An essential advantage of the atomic layer deposition is the fact that the entire substrate surface is coated uniformly. The deposition takes place irrespective of the geometry of the substrate surface, i.e. it is conform to the surface. The first dielectric layer is therefore deposited at the same thickness all over. This is beneficial in particular in surface-textured solar cells or in solar cells with channels which are intended to electrically contact the front with the back of the solar cell (what are known as EWT (emitter wrap through) solar cells), as passivation of the entire relevant solar cell surface can be ensured.

74    The specification then turns to the second dielectric layer. It provides that in one embodiment of the method, the second dielectric layer comprises silicon nitride, silicon oxide and/or silicon carbide each of which is said to display very good optical properties. In addition, dielectric layers made of these materials can also contain a high hydrogen content which can help further passivate the solar cell. It goes on to say that, in one embodiment, the second dielectric layer is produced by means of a PECVD method using reactants such as silane, dinitrogen oxide, carbon dioxide, ammonia and/or methane, which are reacted by igniting a plasma and can produce high-quality dielectric layers which are made of silicon nitride, silicon oxide or silicon carbide and can in addition have a high hydrogen content, that content being preferably at least 1 at. % and more preferably at least 5 at. %. The specification explains (page 8 lines 25 to page 9 line 2):

The embedded hydrogen can diffuse at least in part through the first dielectric layer positioned there below and contribute to passivation there by saturating free bonds of the silicon (“dangling bonds”). It has been found that this contribution can even be still higher than in the case in which a hydrogen-containing dielectric is deposited directly on a silicon surface.

75    The specification explains that a high temperature step (preferably above 800 °C) after depositing the second dielectric layer not only can be used to fire metal contacts which were printed onto the solar cell surface beforehand, but also has the advantage that hydrogen in the second dielectric layer can easily diffuse at elevated temperatures through the first dielectric layer and saturate bonds of the silicon that are still free which can lead to a further improvement in the passivating effect.

76    The specification then turns to the second aspect of the invention and describes a solar cell product in the following terms at page 9 line 28 to page 10 line 11:

According to a second aspect of the present invention, a solar cell is proposed comprising a silicon substrate; a first dielectric layer comprising aluminium oxide on a surface of the silicon substrate; and a second dielectric layer on a surface of the first dielectric layer, the materials of the first and the second dielectric layer differing and hydrogen being embedded into the second dielectric layer.

It should be noted that the embodiments, features and advantages of the invention have been described mainly in relation to the manufacturing method according to the invention. However, a person skilled in the art will recognise both from the foregoing and from the subsequent description that, unless otherwise indicated, the embodiments and features of the invention are also transferable by analogy to the solar cell according to the invention. In particular, the features of the various embodiments may also be combined with one another in any desired manner.

77    The specification then provides a summary of how it is that the invention so described is distinguished from the prior art known methods before turning to a Brief Description of one drawing and a Detailed Description of Embodiments (page 10 line 13 to page 11 line 6):

In summary, the method or the solar cell according to aspects and embodiments of the present invention is distinguished from previously known methods for the surface passivation of crystalline silicon solar cells or solar cells coated in this way inter alia in terms of the following points:

(i) very good surface passivation, such as is necessary for achieving high degrees of solar cell efficiency, can be achieved even after a firing step in the temperature range of 800-900 °C;

(ii) both low and high doped n- and p-type silicon surfaces can be passivated very effectively;

(iii) on account of the high negative charge density in the Al2O3 layer on p-type silicon, no inversion layer is induced below the passivating layer in the silicon, allowing the harmful effect of a "parasitic shunt" to be substantially avoided;

(iv) the layers contain no pinholes;

(v) it is possible to achieve in a simple manner very good optical properties of the layer system that can be adapted very easily to the requirements of the solar cell by way of the thickness and the composition of the, for example PECVD-deposited, layer, so that the layer system can for example be embodied as an antireflection layer on the front of the solar cell or as an infrared reflector on the back of the solar cell in combination with a metal coating over the entire surface of the passivating layer.

78    The Detailed Description refers to Figure 1, which illustrates schematically a solar cell according to one embodiment of the invention including a silicon wafer 1, aluminium oxide thin layer 3, metal contacts 7, 9 and silicon oxide thin layer 5.

79    In the Detailed Description of Embodiments, a manufacturing method is described. In it, a silicon wafer, into which an emitter on a surface was diffused beforehand and the surface of which was “cleaned thoroughly”, is introduced into an evacuated coating chamber and an aluminium-containing compound is fed into the chamber as a reactant. Chemisorption causes the molecules of the reactant to be deposited on the silicon surface until the surface is saturated and non-chemisorbed molecules of the reactant are removed from the chamber with a flushing gas such as nitrogen. Then an O₂ plasma is ignited above the silicon surface to be passivated (or in a separate chamber) and the oxygen radicals react with the chemisorbed molecules to form Al₂O₃. In the best of cases, a monomolecular aluminium oxide layer is formed and the cycle is repeated until the desired thickness is reached using the ALD coating process about 40 or 50 times.

80    Two variants of ALD are described. The first is “plasma-assisted ALD”. The second is “thermal ALD”. In relation to the latter, the specification says (page 12 lines 27 to page 13 line 1):

Alternatively, the Al₂O₃ thin layer 3 can also be deposited by means of thermal ALD, as described in the literature in M. Ritala et al., Atomic layer deposition of oxide thin films with meal alkoxides as oxygen sources, Science 288, 319-321 (2000), for example.

81    The specification next provides that the Al₂O₃ thin layer which is deposited on the silicon wafer is subsequently coated in a PECVD reactor with a silicon oxide thin layer in a continuous process at a high deposition rate and then metal contacts are applied, for example, by screen printing on the front and back of the coated silicon substrate, and fired-in in a continuous furnace at about 700-900 °C.

82    The specification concludes with the following (page 13 lines 19 to page 14 line 11):

In summary and in other words, aspects of the present invention may be described as follows:

A method is proposed for forming a stack layer, the stack layer consisting of two partial layers:

(i) a very thin (for example ≤ 10nm) aluminium oxide thin layer formed by atomic layer deposition (ALD) from an aluminium-consisting gas (for example trimethylaluminium AL₃)₃), and also

(ii) a thicker (> 30nm) silicon oxide-containing thin layer which can be formed, for example by means of plasma enhanced chemical vapour deposition (PECVD), from the gases silane (SiH₄) and dinitrogen oxide (N₂O)) or carbon dioxide (CO₂).

The second layer may also be, instead of a silicon oxide thin layer, a silicon nitride-containing thin layer formed from the gases silane (SiH₄) and ammonia (NH₄) by means of PECVD, or a silicon carbide-containing thin layer formed from the gases silane (CkH₄) and methane (CH₄). The thin layers made of silicon oxide, silicon nitride or silicon carbide, which are deposited by means of PECVD, have a very high hydrogen content (for example > 5 at. %) and therefore serve as a source of hydrogen during a firing step in the temperature range of 700-900 °C. The hydrogen diffuses through the ultrathin Al₂O₃ layer and passivates unsaturated silicon bonds (“dangling bonds”) at the Si/Al₂O₃ interface, leading to very good surface passivation after the firing step. In this way, the combination according to the invention of the two known deposition methods, ALD and PECVD, allows the formation of a firing-stable passivating layer which is optimally suitable for solar cells.

5.2    The Claims

83    Below are the claims of the invention, into which integer letters have been added to claims 1 and 9 for convenience. The parties proceeded on the basis that the numbers in parentheses, which appear in the claims of the patent, identify aspects of the invention identified in figure 1.

1.    (a)     Method for manufacturing a silicon solar cell, including the following steps:

(b)     providing a silicon substrate (1);

(c)     depositing a first dielectric layer (3) on a surface of the silicon substrate by means of atomic layer deposition, wherein the first dielectric layer comprises aluminium oxide; and

(d)     depositing a second dielectric layer (5) on a surface of the first dielectric layer (3), the materials of the first and the second dielectric layer differing and hydrogen being embedded into the second dielectric layer.

2.     Method according to claim 1, wherein, for depositing the first dielectric layer, the silicon substrate is firstly flushed with an aluminium-containing compound comprising at least one of the components Al(CH₃)₃, AlCl₃, Al(CH₃)2Cl and (CH₃)2(C₂H₅)N:AlH₃, so that an aluminium-containing layer is deposited on the surface of the silicon substrate, and wherein the aluminium-containing layer is subsequently oxidised to higher valency in an oxygen-containing atmosphere.

3.     Method according to one of claims 1 or 2, wherein the second dielectric layer comprises a material selected from the group comprising silicon nitride, silicon oxide and silicon carbide.

4.     Method according to one of claims 1 to 3, wherein the second dielectric layer is manufactured by means of a PECVD method.

5.     Method according to one of claims 1 to 4, wherein the second dielectric layer is deposited in such a way that it has a hydrogen content of at least 1 at. %, preferably at least 2 at. % and more preferably at least 5 at. %.

6.     Method according to one of claims 1 to 5, wherein a high-temperature step is carried out at temperatures above 600 °C preferably above 700 °C and more preferably above 800 °C, after the depositing of the second dielectric layer.

7.     Method according to one of claims 1 to 6, wherein the first dielectric layer is deposited at a thickness of less than 50 nm, preferably less than 30 nm and more preferably less than 10 nm.

8.     Method according to one of claims 1 to 7, wherein the second dielectric layer is deposited at a thickness of more than 50 nm, preferably more than 100 nm and more preferably more than 150 nm.

9.     (a) Solar cell comprising:

(b) a silicon substrate (1):

(c) a first dielectric layer (3) comprising aluminium oxide on a surface of the silicon substrate (1)(d) wherein the first dielectric layer has a thickness of less than 50nm, preferably less than 30 nm and more preferably less than 10 nm;

(e) a second dielectric layer (5) on a surface of the first dielectric layer (3), (f) the materials of the first and second dielectric layer differing (g) and hydrogen being embedded into the second dielectric layer.

10.     Solar cell according to claim 9 wherein the first dielectric layer is deposited by means of atomic layer deposition, so that it is substantially atomically tight.

11.     Solar cell according to claim 9 or 10 wherein the second dielectric layer comprises silicon nitride.

12.     Solar cell according to one of claims 9 to 11, wherein the second dielectric layer has a thickness of more than 50 nm, preferably more than 100nm and more preferably more than 150 nm.

13.     Solar cell according to any one of claims 9 to 12, wherein the second dielectric layer has a thickness of more than 100 nm.

14.     Solar cell according to any one of claims 9 to 13, further comprising a plurality of metal contacts, wherein the metal contacts pass through the first dielectric layer and the second dielectric layer.

16.     Solar cell according to any one of claims 9 to 14, wherein the surface of the silicon substrate is passivated by hydrogen.

17.    Solar cell according to any one of claims 9 to 16, wherein the first dielectric layer passivates a region of the silicon substrate of conduction type p.

18.    Solar cell according to claim 17, wherein the surface of the silicon substrate is at the back of the solar cell.

19.    Solar cell according to claim 18 wherein the second dielectric layer forms part of a back surface reflector.

20.    Solar cell according to claim 19, wherein the back surface reflector further comprises a metal coating over a back surface of the second dielectric layer.

21.    Solar cell according to any one of claims 9 to 20, wherein the thickness of the first dielectric layer is more than about 2 nm.

22.    Solar cell manufactured using a method according to one of the preceding claims 1 to 8.

5.3    The nature and purpose of the claimed invention

84    The experts aptly summarise in the Construction JER that the purpose of the claimed invention is to provide temperature-stable passivation of surfaces of silicon solar cells, while avoiding some of the drawbacks of surface passivation methods known at the time. They agree that the nature of the claimed invention is the use of a high temperature stable dielectric stack consisting of a thin layer of aluminium oxide, which has a high density of negative charge, and a thicker layer of a different dielectric material that contains hydrogen, which is released upon annealing, further contributing to the surface passivation and to its thermal resilience.

85    It may be noted, however, that the patent does not disclose or describe a completed solar cell. It relates to, and describes, an aspect of a solar cell involving the double dielectric layers of the claims which are useful for passivating the surface of the silicon substrate. As the five experts involved in the preparation of the Construction JER agreed, being Dr Rentsch, Professor Cuevas-Fernandez, Professsor Weber, Dr Ruby and Dr Glew (construction experts), further work would have been required in the development of equipment and processes suitable for photovoltaics manufacturing in particular in relation to the use of ALD in the method claimed.

5.4    The skilled addressee

86    Skilled addressees are those likely to have a practical interest in the subject matter of the invention: Catnic Components v Hill & Smith Ltd [1982] RPC 183 at 242 (Diplock LJ). There may be more than a single person with such an interest, and the notional skilled reader to whom the document is addressed may not be a single person but a team, whose combined skills would normally be employed in that art in interpreting and carrying into effect instructions such as those which are contained in the document to be construed: General Tire & Rubber Co v Firestone Tyre & Rubber Co Ltd [1971] 7 WLUK 130; [1972] RPC 457 at 485 (Sachs LJ). Put another way, the skilled addressee is a notional person who may have an interest in using the products or methods of the invention, making the products of the invention, or making products used to carry out the methods of the invention either alone or in collaboration with others having such an interest: Aristocrat Technologies Australia Pty Limited v Konami Australia Pty Limited [2015] FCA 735; 114 IPR 28 at [26] (Nicholas J); Pharmacia LLC v Juno Pharmaceuticals Pty Ltd [2022] FCA 92; 165 IPR 200 at [111] (Burley J).

87    The patent is broadly directed to a method for manufacturing a solar cell and a solar cell with a surface passivating dielectric double layer, being a two dielectric layer stack, the first of which comprises aluminium oxide.

88    Hanwha submits that the person skilled in the art should be limited to a person who is qualified and experienced in using solar cell manufacturing processes in commercial or industrial settings. REC Solar submits that the relevant person skilled in the art is somewhat broader, contending that to take the disclosure of the patent and implement it industrially would have required the work of a notional team, consisting of industry participants but also researchers and equipment manufacturers.

89    In my view the patent is addressed to persons having a good understanding of silicon solar cell technology used by the photovoltaics industry. They would have at least an undergraduate degree in a relevant field such as science or engineering and have either research or industry experience working in the field whether in an applied research institution working on photovoltaics research or working in industry. Although Hanwha submits that the skilled addressee is to be confined to a person working in industry, I consider that description to be too confined. Whilst it is true that in parts the patent refers to a solar cell in its completed state, it is notable that the first problem identified in the specification is of the prior art in the form of the use of high temperature steps used in the production of laboratory solar cells, which are not in general use in industrially produced solar cells. Furthermore, the experts agreed in the Construction JER that the patent provides a general guide to the implementation of the invention but significant work would have been required to determine which technique was most suitable for the design of equipment and processes for industrial use. This would have involved collaboration between equipment manufacturers (such as in the use of ALD equipment) or research institutions or both. In this regard, the evidence going to the background and experience of Professors Rentsch, Weber and Cuevas-Fernandez supports the view that academic researchers in the field were engaged in considerable collaboration with industry. Furthermore, Dr Winderbaum’s experience indicates that those in industry are likely to collaborate with those working in research institutions in making developments in solar cell technology.

90    Accordingly, where I refer below to the person skilled in the art or the skilled worker, that construct refers to persons who are researchers in academia focussed on photovoltaic cells in the context of solar cell design and/or workers in industry who are engaged in the manufacture of such solar cells. I find that workers in academia and industry worked in close collaboration and as such would readily work in a team on the development of products.

91    In this regard, I consider that each of Professors Weber, Professor Cuevas-Fernandez, Dr Rentsch and Dr Winderbaum fall within the description of the skilled worker. Dr Glew, with his background and experience in the supply of equipment used for the manufacture of silicon chips, is less squarely within the field, although his experience as a supplier to solar cell manufacturers, his depth of knowledge in the field as a materials scientist experienced in the use of PECVD of dielectric films and his obvious understanding of the intricacies of the technology underlying the disclosure of the patent is such that I find that his evidence is of some assistance.

6.    CLAIM CONSTRUCTION

6.1    Introduction

92    The claim construction issues in the proceeding largely, but not exclusively, concern claims 1 and 9. They arise for various reasons. Several concern non-infringement arguments, others arise in the context of novelty arguments and others are relevant to points arising from allegations of inutility or non-compliance with s 40 of the Patents Act. It is appropriate to address all construction issues separately and before turning to the these arguments, or, as the authorities say, “as if the infringer had never been born”; CCOM Pty Ltd v Jeijing Pty Ltd [1994] FCA 396; 51 FCR 260 at 267-268 (Spender, Gummow and Heerey J); Pharmacia LLC at [117] (Burley J).

93    The matters addressed below concern the proper meaning of the following terms in claim 9:

(1)    “dielectric layer”;

(2)    “depositing a first dielectric layer on a surface of the silicon substrate”;

(3)    “depositing a second dielectric layer on a surface of the first dielectric layer”;

(4)    “first dielectric layer comprising aluminium oxide”;

(5)    “and hydrogen being embedded into the second dielectric layer”.

94    Additional disputes arise from the following terms in claims dependent on claim 9 being:

(6)    “substantially atomically tight” in claim 10;

(7)    “second dielectric layer comprises silicon nitride” in claim 11;

(8)    “wherein the surface of the silicon substrate is passivated by hydrogen” in claim 16; and

(9)    “second dielectric layer forms part of a back surface reflector” in claim 19.

95    For convenience, I reproduce claim 9 with integers marked as letters:

(a) Solar cell comprising:

(b) a silicon substrate (1):

(c) a first dielectric layer (3) comprising aluminium oxide on a surface of the silicon substrate (1)(d) wherein the first dielectric layer has a thickness of less than 50nm, preferably less than 30nm and more preferably less than 10nm;

(e) a second dielectric layer (5) on a surface of the first dielectric layer (3), (f) the materials of the first and second dielectric layer differing (g) and hydrogen being embedded into the second dielectric layer.

96    Integers (c) and (d) identify a dielectric layer with a number of relevant characteristics including: that it must be a “first” dielectric layer; that it must be “on a surface of the silicon substrate”; that it must “comprise” aluminium oxide; and that it must have a maximum thickness. Integers (e), (f) and (g) identify further characteristics that a further dielectric layer must have including: that it be a “second” dielectric layer; that it be “on a surface of the first dielectric layer”; that it be of materials differing from the first dielectric layer; and that hydrogen be embedded into it.

97    The construction experts gave evidence in chief going to construction of the patent. Each participated in the preparation of Construction JER and each gave concurrent evidence addressing these issues. Their evidence was of considerable assistance in clarifying aspects of the disputed common general knowledge relevant to questions of construction, explaining the technology and identifying the meaning of terms and phrases used in the patent.

98    As a matter of context, it may be noted that the infringement allegations against LONGi and Jinko included that claim 1 and some of its dependent claims had been infringed. Validity challenges advanced by LONGi and Jinko (but not REC Solar) also raised questions of construction concerning claim 1 and some of its dependent claims. As a result of the settlement of the LONGi and Jinko proceedings, it is not strictly necessary to consider these questions. However, the parties in closing submissions (including REC Solar) often developed their construction arguments by reference to all of the claims in suit, including claim 1. At the time, that was a logical course to take. In addressing the construction issues relevant to claims 9 and its dependent claims in this judgment, I necessarily address the arguments as presented by the parties at trial, which for the most part first addressed the equivalent construction question in relation to claim 1 and then submitted that the same or equivalent word or phrase had the same meaning in claim 9.

99    Claim construction is, of course, a matter for the Court, although it is aided by the evidence of experts who can assist as to the way in which the hypothetical skilled reader would understand the claims having regard to the common general knowledge as at the priority date. In broad terms, the task of the Court is put itself in the position of the skilled addressee and, with the aid of the background knowledge in the field, to construe the language of each claim, which has been deliberately chosen by the patentee, as it sits in the context of the specification as a whole.

100    Although many cases have referred to the principles applicable to claim construction, one convenient authority that summarises key aspects of those principles is Jupiters Ltd v Neurizon Pty Ltd [2005] FCAFC 90; 65 IPR 86 at [67] where Hill, Finn and Gyles JJ said:

(i)    the proper construction of a specification is a matter of law: Décor Corp Pty Ltd v Dart Industries Inc (1988) 13 IPR 385 at 400;

(ii)    a patent specification should be given a purposive, not a purely literal, construction: Flexible Steel Lacing Company v Beltreco Ltd (2000) 49 IPR 331 at [81]; and it is not to be read in the abstract but is to be construed in the light of the common general knowledge and the art before the priority date: Kimberley-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 at [24];

(iii)    the words used in a specification are to be given the meaning which the normal person skilled in the art would attach to them, having regard to his or her own general knowledge and to what is disclosed in the body of the specification: Décor Corp Pty Ltd at 391;

(iv)    while the claims are to be construed in the context of the specification as a whole, it is not legitimate to narrow or expand the boundaries of monopoly as fixed by the words of a claim by adding to those words glosses drawn from other parts of the specification, although terms in the claim which are unclear may be defined by reference to the body of the specification: Kimberley-Clark v Arico at [15]; Welch Perrin & Co Pty Ltd v Worrel (1961) 106 CLR 588 at 610; Interlego AG v Toltoys Pty Ltd (1973) 130 CLR 461 at 478; the body of a specification cannot be used to change a clear claim for one subject matter into a claim for another and different subject matter: Electric & Musical Industries Ltd v Lissen Ltd [1938] 56 RPC 23 at 39;

(v)    experts can give evidence on the meaning which those skilled in the art would give to technical or scientific terms and phrases and on unusual or special meanings to be given by skilled addressees to words which might otherwise bear their ordinary meaning: Sartas No 1 Pty Ltd v Koukourou & Partners Pty Ltd (1994) 30 IPR 479 at 485-486; the Court is to place itself in the position of some person acquainted with the surrounding circumstances as to the state of the art and manufacture at the time (Kimberley-Clark v Arico at [24]); and

(vi)    it is for the Court, not for any witness however expert, to construe the specification; Sartas No 1 Pty Ltd, at 485-486.

101    There was no real dispute between the parties as to the principles relevant to construction of the claims, although they did disagree as to the application of those principles.

6.2    “dielectric layer” in claim 9

6.2.1    The arguments

102    Hanwha submits that a “dielectric layer” is “a planar sheet of electrically insulating material that is typically very thin” and emphasises that the term is applied to solar cells for their “dielectric properties, as insulators or to provide surface passivation”. As a consequence, not all layers are dielectric layers and the dielectric properties of a layer will depend on the thickness of what is deposited, which would change the functionality or the properties of the layer.

103    REC Solar submits that a dielectric layer is a planar sheet of electrically insulating material that is typically very thin relative to its extension and is distinguishable from adjacent layers or regions by having a different composition and different properties. It disputes that it is a requirement of claim 9 that a “dielectric layer” have demonstrated insulation and passivation qualities in situ. It furthermore submits that an “interfacial layer” of silicon oxide is plainly a dielectric layer within the meaning of claim 9.

6.2.2    The expert evidence

104    In the Construction JER the experts agreed that a “dielectric layer” is:

… a planar sheet of electrically insulating material that is typically very thin relative to its extension and that is distinguishable from adjacent layers or regions by having a different composition and different properties.

105    They further added the reasons why dielectric layers are used in silicon solar cells, being because of:

… a) their optical properties, such as transparency and refractive index, and b) their dielectric properties, as insulators or to provide surface passivation, and their ability to provide complete coverage of the surface.

106    There was some debate in the evidence as to what electrical properties might be required before the claim requirement of a “first dielectric layer” is met.

107    Professor Cuevas-Fernandez and Dr Rentsch in the Construction JER expressed the view that a dielectric layer material such as silicon oxide would not be able to form a “dielectric layer” within the claim if it were too thin because “ultrathin layers do not provide per se insulation nor surface passivation”.

108    Professor Weber and Drs Glew and Ruby considered that a dielectric layer may include any dielectric material that is present as a layer. They considered that the thickness was not relevant. They point to the specification at page 9 which refers to layers of aluminium oxide that are as thin as 0.5 nm as “dielectric layers”.

109    In his oral evidence, Professor Cuevas-Fernandez clarified his position. He explained that when he read the claims, he understands a reference to “dielectric layer” as simply to “a class of materials … not because it has to have dielectric properties per se”.

110    Dr Rentsch accepted that silicon oxide “is in principle a dielectric material” but qualified this by saying that “it depends on … what the properties are”. However, taking silicon oxide as an example, it might be noted that the thickness of a particular layer does not have an impact on whether it is a dielectric layer – as Dr Rentsch accepted in his oral evidence, the band gap of silicon oxide does not change irrespective of its thickness. In this regard it may be recalled from the agreed common general knowledge set out in Annexure A that a dielectric layer is an electrical insulator, which is a poor conductor of electrical current that can be polarised in an electric field. An insulator is characterised by the fact that, unlike conductors, it will have a large band gap such that at room temperature few electrons from the valence band have sufficient energy to jump the band gap to reach the conduction band.

111    In his oral evidence, Dr Rentsch accepted that whatever effect on passivation an ultra-thin layer of dielectric material such as silicon oxide may have on its own, “it would be likely to have some insulation or passivation effect in combination with other layers”. This was consistent with the evidence of the respondents’ experts.

6.2.3    Consideration

112    The present argument concerns the identification of what may be called a “dielectric layer”, whether it be the first or second such layer in claim 9 within integer 9(c).

113    Although REC Solar couches its submissions by reference to whether or not an interfacial oxide is a dielectric layer within claim 9, that argument tends to distract from the more abstract question as to the proper construction of the claim.

114    As I have noted, the experts agreed that a “dielectric layer” is a separately distinguishable planar sheet of electrically insulating material. Whilst Dr Rentsch sought to impose a requirement (which Hanwha adopts) that, for a dielectric layer to be present in a solar cell, it had to have demonstrated passivation or insulation characteristics, for the following reasons I do not consider that is a requirement of the claim.

115    First, the integers of claim 9 do not prescribe the result to be achieved by the constituent parts, but rather the materials from which the parts are to be made and their location. As each of the construction experts apart from Dr Rentsch accepted, they understand that a reference to a “dielectric layer” is a reference to a class of materials understood by those in the field to have dielectric properties. In my view that is a more natural way to read the claim: dielectric layer is a layer made up of a material of a certain type.

116    Secondly, the claims do not specify that a particular dielectric layer must passivate the solar cell at all. Rather, the invention is directed towards a two layered dielectric stack which in combination achieves that effect.

117    Thirdly, the expert evidence was that, when considering the product of claim 9, any passivation may not arise simply as a result of the first dielectric layer, but as a result of the two layers. As a consequence, as Dr Rentsch accepted, a first dielectric layer alone may not have passivation properties, but as part of a stack it may well. It would be an impractical approach to the identification of the materials to be used in the solar cell of claim 9 to construe a layer made of a recognised dielectric material as not a “dielectric layer” within the claim unless it was established by experimental evidence that it functions in a certain way. I do not understand the patent specification to disclose such a requirement and do not consider this to be a practical way to read the claim.

118    Fourthly, I do not accept the suggestion that emerged from the evidence of Dr Rentsch that a sheet of a dielectric material should not be characterised as a dielectric layer if it is “ultra-thin” because it is in the order of 1-2 nm thick. Claim 9 does not impose a minimum thickness of the layer. Nor do any other of the claims. Indeed, whilst a number of claims, including claim 9, prescribe maximum thicknesses for the layer, none prescribe minimum thicknesses.

119    Furthermore, the teaching of the specification plainly encourages the use of very thin layers. For instance, on page 9 lines 14-20, in the context of using ALD as the method of deposition, the specification provides that the thinner the layer is, the more rapidly it can be deposited and that even at very low thicknesses, the first dielectric layer offers very good surface-passivating properties on account of the high quality which can be achieved using ALD, “although a minimum thickness of about 0.5 nm, preferably about 2 nm, should not be undershot in order to ensure tightness of the layer” (emphasis added). The emphasised words refer to the completeness of the coverage rather than passivation effect.

120    Finally, for completeness I find that silicon oxide formed on a silicon substrate was before November 2007 recognised by those skilled in the art to fall within the class of materials known to be dielectric. This view is supported by the agreed common general knowledge and the teaching of the specification which, for instance, at page 8 discloses that the second dielectric layer may comprise silicon oxide. This was not a point disputed by either Dr Rentsch or Professor Cuevas-Fernandez.

6.3    “depositing a first dielectric layer on a surface of silicon substrate”; claim 9

6.3.1    Introduction

121    The central dispute between the parties concerning the meaning of the claims at trial arose in the context of integer 1(c) of claim 1 and integer 9(c) of claim 9 and focussed on the question of what those claims require for a first dielectric layer to be on a surface of the silicon substrate. In particular, does it mean that the first dielectric layer must be on the silicon substrate itself or can other material, particularly a silicon oxide, be present and the integer still be met?

122    Hanwha submits that “the thermal growing of a very thin silicon oxide or the presence of a very thin interfacial oxide” does not “avoid” the integer in claim 1(c) of “depositing a first dielectric layer on a surface of the silicon substrate” or in claim 9(c) of a “first dielectric layer … on a surface of the silicon substrate”.

123    REC Solar submits first, that that the words “depositing a first dielectric layer” require that no other dielectric layer has been formed, grown or deposited, and secondly that the phrase “on a surface of the silicon substrate” means “on the outer face of the silicon crystalline structure” or, put another way, the first dielectric layer must be in contact with the silicon crystalline structure of the substrate that is to be passivated.

124    Having regard to the way that the arguments were developed, it is appropriate to observe that the agreed common general knowledge provides that one of the types of passivating layers generally known and used as at November 2007 was thermally grown silicon oxide, which was a known dielectric layer and was primarily (and extensively) used in research before that date. This information formed part of the common general knowledge.

125    Also forming part of the background knowledge of the person skilled in the art considering the disclosure of the patent was native silicon oxide. The construction experts agreed in the Construction JER that before the priority date it was known that a silicon wafer left in air at room temperature may slowly oxidise and develop an “ultrathin” layer of the native silicon oxide at a “very low growth rate on the surface” of the substrate. Such native oxide starts by randomly forming “islands” of a couple of atomic layers of oxygen. It was known that a native silicon oxide so grown does not provide significant passivation of silicon wafers or of highly doped surfaces created in them. One of the reasons why silicon wafers were before the priority date always cleaned – both in the industrial context and also the laboratory context – is that native oxide was known to be undesirable. Such cleaning was typically done using a hydrofluoric acid etch.

126    It was known that during the time between the cleaning of the surface of the silicon substrate and further processing steps, whilst some atomic level islands of silicon oxide may have formed, the growth rate was so slow that typically the native oxide would be in amounts that are considered to be trace elements which are not material.

6.3.2    The arguments

127    Hanwha advances three arguments in support of its construction.

128    First, it submits that the very thin silicon oxide “forms part of the surface of the silicon substrate”. In this regard it submits that the term “depositing” (in claim 1) connotes that the first dielectric layer is “added to” the surface of the silicon substrate. Drawing on a dictionary definition, Hanwha submits that “substrate” relevantly means “something which underlies, or serves as a basis or foundation” such that the words “on a surface” simply require that the first dielectric layer be on the silicon substrate, which means “on the silicon wafer” or “the layer that is closest to the substrate”. The purpose of the phrase “on a surface” in claims 1 and 9 is simply to indicate that the first dielectric layer can be deposited on either or both of the front or rear surfaces of the silicon substrate. It submits that there is no reason to consider that the silicon substrate must be “free of silicon oxide”, whether that be a native oxide, interfacial oxide or silicon oxide deliberately grown before the deposition of the first layer. Properly understood, any oxide region formed by oxidation of the surface of the silicon substrate “forms part of the surface of the silicon substrate”.

129    Hanwha submits that nothing in the patent requires that the surface of the silicon substrate exclude oxygen and claim 1 is “agnostic” (ie, neutral) to whether or not the silicon substrate is oxidised or not.

130    Hanwha submits that its construction is supported by the text of the claim which does not define the condition of the surface of the substrate, the disclosure of the specification and the nature and purpose of the invention. It criticises REC Solar’s approach as being too heavily reliant on expert evidence, involving a meticulous verbal analysis of the claim which eschews a purposive construction and lacking a measure of common sense. Furthermore, even if a person skilled in the art performed thermal ALD, it submits that based on the disclosure of Ritala (cited as M. Ritala et al., Atomic layer deposition of oxide thin films with meal alkoxides as oxygen sources, Science 288, 319-321 (2000) in the specification), an interfacial oxide would form unless metal alkoxides are used, and the patent does not teach that they be used. It submits that the reference to Ritala in the specification teaches the person skilled in the art that the presence of interfacial oxide during the course of ALD is likely and accordingly supports its construction.

131    In the alternative, Hanwha submits that if silicon oxide is not characterised as forming part of the surface of the substrate, the claim ought not to be construed as requiring that the first dielectric layer be directly on or in direct adhesion with a surface of the silicon substrate. Hanwha advances several arguments in support of its position. First, the phrase “on the surface” simply means on one or both of the front or back of the surfaces of the substrate and that the first dielectric layer must be closer to the substrate of the two dielectric layers referred to in the claim. Secondly, the word “on” does not require direct contact. Thirdly, direct contact is not required to achieve a passivating effect. Fourthly, this construction does not require the Court to consider a particular silicon oxide thickness beyond which the first dielectric layer is no longer “on a surface” because that does not arise in the present case. Fifthly, if, on this construction, an intermediate layer lies on the silicon substrate which falls within a definition of itself being a “dielectric layer”, then the requirements of the claim will nonetheless be met if there is “a first dielectric layer” which is part of a two layer stack which is otherwise within the scope of the claim.

132    In further alternative, Hanwha contends that the “first dielectric layer” is necessarily any dielectric layer that is the first to be deposited on a surface of the silicon substrate as part of the double dielectric passivating stack of the invention or, if the Court rejects this construction, the “first dielectric layer” is necessarily any “dielectric layer” that is the first in time to be deposited on a surface of the silicon substrate.

133    Finally, Hanwha advances an argument based on the reasoning of the Full Court in Fresenius Medical Care Australia Pty Ltd v Gambro Pty Ltd [2005] FCAFC 220; 67 IPR 230 at [49]-[51], [70], [103]. It submits that, whilst there will be no infringement unless the alleged infringer has taken all of the essential features of the patentee’s claim, in considering infringement it is “the substantial idea disclosed by the specification and made the subject of a definite claim” that may be considered. It submits that when considering infringement of a claim to a combination, a relevant question is whether the alleged infringement “is the same in substance and effect or is substantially a new or different combination”. It adds that the inclusion of additional integers to a claimed combination does not necessarily avoid infringement if those additional integers are properly characterised as inessential or do not make a new working of the combination and all of the essential integers of the claimed combination are present; Fresenius at [70].

134    Hanwha submits that, weighing the expert evidence as a whole, the court should find that: first, there is no relevant difference between the surface passivating properties of an interfacial oxide and a thermally grown silicon oxide; secondly, such very thin oxides do not provide any surface passivation on their own; and, thirdly, to the extent that such very thin oxides contribute to the surface passivation in an aluminium oxide-silicon nitride double dielectric layer, such contribution makes no material difference to the surface passivation of the dielectric layer stack and so does not result in a new working of the combination within Fresenius at [70].

135    REC Solar submits that the words “on a surface of the silicon substrate” mean that the first dielectric layer must be “on the outer face of the silicon crystalline structure” and that “depositing a first dielectric layer” requires that no other dielectric layer has been deposited, grown or formed before that layer.

136    It contends that its construction of “on a surface of the silicon substrate” is supported by the ordinary meaning of the word “surface” as an “outer face”, the disclosures pointing in that direction in the specification and the context given by the proven common general knowledge. It further submits that the construction proposed by Hanwha is not open to it having regard to the expert evidence.

6.3.3    Consideration

137    For the reasons set out below, I reject the various constructions propounded by Hanwha. As the parties’ submissions were primarily directed to claim 1, and neither submitted that this aspect of claim 9 should be understood differently, I address the construction of both claims 1 and 9, commencing with claim 1.

138    Claim 1 is for a method. After the step of providing a silicon substrate, the next step is depositing a first dielectric layer of aluminium oxide on the substrate.

139    The skilled reader would understand the “silicon substrate” to be the silicon wafer the surface of which requires passivation. It was common general knowledge at the priority date that silicon was a semiconductor, the function of which in a solar cell is to convert incident light into energy by exciting valence electrons into the conduction band. Silicon is doped in order to promote directional flow. Typically, the silicon substrate was a wafer which had been subject to several processing steps, including the diffusion of dopants into it to form a pn junction before depositing dielectric layers onto it. Armed with this understanding, the person skilled in the art would most naturally consider the silicon substrate of integer 1(b) to be the silicon substrate itself together with dopant and incidental impurities.

140    Further, the words “depositing a first dielectric layer on a surface of the silicon substrate” in claim 1 are positional. They identify a location where the layer is to be placed. The Macquarie Dictionary defines “surface” as “outer face” (3rd ed, Macquarie Dictionary Publishers, 1997). “Substratum” is defined to mean “that which is spread or laid under something else”. A “substrate” is something “which underlies or serves as a basis or foundation”.

141    The natural and ordinary meaning of the contested words in integer 1(c) and integer 9(c) is that the first dielectric layer is to be placed on an outer face of the silicon substrate being the semiconductor material used in the solar cell, including dopant and may include trace or de minimis amounts of contaminants or impurities. The words “on a surface of” emphasise that it is not simply to be placed “on” the silicon substrate – perhaps like a shoe may be placed on a foot, despite the presence of a sock – but on the surface of the silicon substrate, like a sandal is placed on the foot, absent any intervening layer. It is true that the integer could perhaps be understood to require that the dielectric layer is to be located on any surface of the substrate, front back or sides, regardless of whatever else was on it, but if that was the meaning, the integer could have simply required that the first dielectric layer be deposited “on the silicon substrate”. The preferable construction gives work to the words “on a surface of”.

142    Furthermore, integers 1(d) and 9(e) require that the second dielectric layer be deposited “on a surface of the first dielectric layer” which tends to reinforce the positional significance of the steps set out in the method.

143    When one considers the disclosure of the specification this construction of integers 1(c) and 9(c) is reinforced.

144    First, the “silicon substrate” is described in terms as “a thin monocrystalline or multicrystalline silicon wafer or else a silicon thin wafer” (page 5 lines 21-22). No reference is made to any surface other than the silicon of the wafer onto which the first layer is to be placed. The specification provides no basis upon which the skilled reader might infer that the first dielectric layer is to be placed on a silicon substrate which has upon it or includes thermally grown or “native” silicon oxides, as Hanwha contends.

145    Secondly, when the specification refers to the surface of the silicon substrate, that reference is to the outer face of the silicon crystalline structure only. In one embodiment the specification instructs (page 6 lines 7-9):

Before the depositing of the first dielectric layer, the surface of the silicon substrate can be thoroughly cleaned, so that no contamination remain thereon that might disturb the subsequently deposited dielectric layer. In particular, the surface of the silicon substrate can be slightly etched away, for example in a solution which on the one hand contains an oxidising agent and which on the other hand contains hydrofluoric acid (HF) which etches away the oxidised silicon oxide. A suitable method known in the production of solar cells is for example what is known as RCA cleaning.

(Emphasis added)

The importance of thorough cleaning of the substrate was reinforced later at page 11 line 22-23. Although this passage quoted refers to the fact that the surface of the silicon substrate “can be” thoroughly cleaned, the expert evidence reveals that those in the field considered this to be a requirement.

146    It is apparent from this passage that cleaning of the “surface” includes the slight etching away of the silicon substrate. Two cleaning steps are mentioned; using an oxidising agent and hydrofluoric acid on the one hand and an RCA cleaning process on the other, both of which slightly etch the silicon surface to remove contaminants from it. The experts agreed that, in the discourse of the specification, oxides as well as metallic materials were being referred to and distinguished in this passage from the substrate or crystalline “surface” of the silicon wafer. The evidence demonstrated that cleaning was a standard process in research and in industry before the priority date and that such cleaning will remove, inter alia, any native oxide and regrowth of any native oxide would not be inevitable, as I discuss below. This was because it was known that the presence of native silicon oxide (and silicon oxide that resulted from the etching process) and other contaminants was generally undesirable because it could adversely impact the deposition of the dielectric layer.

147    Accordingly, in this aspect of the specification the reference to the “surface of the silicon substrate” was exclusively silicon, absent de minimis contaminants including silicon oxide. It tends against the construction proposed by Hanwha to the effect that silicon oxide, however formed, is to be understood to be part of the silicon substrate.

148    Thirdly, other parts of the specification also suggest that the dielectric layer is placed on the crystalline substrate, meaning in intimate physical contact with that substrate without any intervening material or layer.

149    Immediately after the passage quoted above, the specification describes one embodiment where the silicon substrate is firstly flushed with an aluminium-containing compound “so that an aluminium-containing layer is deposited on the surface” which can “cling to the silicon surface at the points at which it enters into contact with the silicon surface”. The teaching is that a “chemical reaction with the silicon surface can occur; this is also referred to as chemisorption” and that “[i]n the best of cases this can lead to the formation of a monomolecular layer made up of molecules of the aluminium-containing compound”. Later, an “essential advantage” of the ALD is said to be the fact that the entire substrate surface is coated uniformly which is said to be beneficial in particular in surface-textured solar cells. The “surface” to be textured here is the crystalline silicon.

150    Furthermore, earlier, in the passage on page 5 lines 10-17 (set out in section 5.1 above) the specification provides that the “key” to understanding the outstanding passivating effect and tempering layer of the invention “may be identified in the combination of the Si/Al2O3 interface, which is ideally atomically flat and is produced as a matter of course during the ALD process” (emphasis added). The word “interface” directs attention to a location where two “faces” of different materials – here silicon substrate and aluminium oxide layer – come into contact. There is no mention of a silicon/silicon oxide/aluminium oxide interface in the patent. Each of Professor Weber and Drs Glew and Ruby understood this to require an “abrupt” interface, thereby indicating no opportunity for an interface between aluminium oxide and any intervening material such as a metallic contaminant or oxide on the surface of the substrate. Whilst Dr Rentsch gave a qualified agreement that the passage teaches that the interface was only “ideally abrupt”, in my view the teaching of the passage is plain, namely that one key to understanding the beneficial passivation effect of the two layered stack of the invention lies in the close interaction between the silicon substrate and the aluminium oxide first dielectric layer. I reject Dr Rentsch’s qualification.

151    In the Construction JER, Professor Weber and Drs Glew and Ruby expressed the view that it was generally well known at the priority date that in heterojunction cells an abrupt interface was critical for good solar cell performance. I accept that evidence. Whilst a heterojunction cell is quite different to the invention described in the patent, the point is that the person skilled in the art would understand this passage, and the subsequent references to cleaning and the process of chemisorption, to reflect a teaching in the specification that in functional terms the passivation benefits of the invention are to be achieved by locating the first dielectric layer on the surface of the crystalline substrate. It was known that the surface of the silicon substrate could oxidise with native oxide and that it was difficult, but by no means impossible, for the surface in a processed solar cell to be oxide-free.

152    As Dr Ruby explained, “chemisorption” is a term referring to the formation of covalent bonds between molecules, in this case the formation of covalent bonds between the aluminium atoms in the precursor and the silicon atoms at the surface of the silicon substrate.

153    Each of the other construction experts agreed with this interpretation, with the exception of Professor Cuevas-Fernandez, who did not consider it sensible to expect that aluminium would form covalent bonds with silicon. Having regard to the views of the other experts, I consider their understanding to be more likely to reflect the understanding of the person skilled in the art.

154    These passages, although directed to preferred embodiments, tend to confirm that in the discourse of the specification and the claims, references to the “surface” of the substrate are references to the silicon substrate itself and indicate that silicon oxide is not part of that surface.

155    Fourthly, the disclosure of the patent is that silicon oxide is to be identified separately as material used in the second dielectric layer. This corresponds with the common general knowledge of those in the art at the priority date that silicon is a dielectric and not a semiconductor. It supports the submission advanced by REC Solar that silicon oxide does not form part of the surface of the silicon substrate.

156    That view is further supported by the evidence of the experts.

157    Dr Rentsch agreed in the context of a specific example posed to him in cross-examination that an interfacial oxide could be readily distinguished from the silicon substrate. When viewing a substrate with almost 20% oxygen, he considered “that this is not any more … the silicon substrate but … whatever kind of amorphous silicon oxide … definitely different to a silicon substrate”.

158    Similarly, Professor Cuevas-Fernandez accepted that a silicon oxide layer is “certainly” distinguishable from the silicon substrate.

159    Dr Glew expressed his view to similar effect as follows:

I know that the silicon semiconductor of the crystalline substrate is no longer a crystalline substrate, it’s now an amorphous material incapable of performing as a semiconductor, when the oxygen starts coming up, and I – and I now have this kind of messy dielectric varying composition and I no longer have a substrate. So I don’t, you know, I think you can’t – you can’t neglect trying to understand the material, the layer that was there previously, and when it no longer acts like that layer.

160    Conversely, there was no general knowledge that an interfacial layer of silicon oxide may form during the ALD process of applying an aluminium oxide layer or that it may form during deposition by any other means, such as PECVD. The experts agreed that the first reported presence of such a layer was in the Hoex 2006 publication, which did not form part of the common general knowledge at the priority date.

161    In my view the specification did not inform or alert such a person of such an artefact.

162    In this regard, it is necessary to divert to address the lengthy evidence and arguments which were advanced concerning the disclosure of the Ritala publication.

163    Hanwha contends that, whilst it was not common general knowledge at the priority date that an interfacial oxide layer formed during the processing of the solar cell, the reference to Ritala in the patent makes clear that the Patent is not teaching that any interfacial oxide layer is to be avoided. Put affirmatively, Hanwha submits that the patent “permits”, by its reference to Ritala, the existence of interfacial oxide layers upon thermal ALD deposition. As Hanwha put it in closing submissions, the reference in the specification to Ritala “underscores that the Patent is not concerned with the avoidance of an interfacial oxide, or indeed any silicon oxide forming at the surface of the silicon substrate”, the consequence being that the invention as described is “indifferent” to whether or not silicon oxide is present prior to the deposition of the first dielectric layer of the invention. Hanwha submits that claims 1 and 9 should be construed accordingly.

164    In my view this convoluted argument must be rejected.

165    The Ritala disclosure is not expressed to be incorporated by reference into the specification. Its relevance should be understood by reference to the context in which it appears; Idenix Pharmaceuticals LLC v Gilead Sciences Pty Ltd [2017] FCAFC 196; 134 IPR 1 at [165] (Nicholas, Beach and Burley JJ); Merck Sharp & Dohme Corporation v Wyeth LLC (No 3) [2020] FCA 1477; 155 IPR 1 at [891] (Burley J).

166    Reference in the patent to Ritala appears after the passages to which I have referred above, where the key to understanding the disclosure of the invention is set out and the general description of embodiments (including references to cleaning and chemisorption) are made. Furthermore, immediately after the heading “Detailed Description of Embodiments”, but before the reference to Ritala, the specification reiterates at page 11 lines 22-24 that the silicon water is “cleaned thoroughly” before being introduced into an evacuated coating chamber, and also repeats that “[c]hemisorption causes the molecule to be deposited on the silicon surface until the surface is saturated”, thereby emphasising the points noted earlier in the specification.

167    The Detailed Description then provides additional information about the first embodiment described, which is plasma-assisted ALD. The specification provides (page 12 lines 17-25):

The variant of ALD described herein is referred to as “plasma-assisted ALD” and is well known from the literature; see for example C. W. Jeong et al., Plasma-assistant atomic layer growth of high-quality aluminium oxide thin films, Jpn. J Appl. Phys. 40, 285-289 (2001). Tests have shown that particularly good surface passivation can be achieved in that the plasma does not have direct contact to the substrates, as, in the event of such contact, ion bombardment can damage the substrate surfaces, but rather burns in a separate chamber from which the radicals are subsequently guided to the substrate surface. This variant of the method is referred to as “remote plasma-assisted ALD” and is described in US 7,410,671, for example.

168    Thus far, the skilled reader has no reason to doubt the matters to which I have referred regarding the surface of the silicon wafer. As I have noted, it was not common general knowledge at priority date that an interfacial oxide would or may be formed at the surface of a silicon substrate during the manufacture of silicon solar cells: the process of ALD in the context of solar cells did not form part of the common general knowledge and it was only after the priority date that an interfacial oxide became known to form in the process of ALD. Nor, as I have noted, could Hoex 2006 be relied upon for that purpose, because that publication was also not part of the common general knowledge.

169    It is only after this passage that Ritala is mentioned at pages 12-13 in the context of an alternative embodiment:

Alternatively, the Al2O3 thin layer 3 can also be deposited by means of thermal ALD, as described in the literature in M. Ritala et al., Atomic layer deposition of oxide thin films with metal alkoxides as oxygen sources, Science 288, 319-321 (2000), for example.

170    It is difficult to see how the context of this disclosure could demonstrate to the person skilled in the art reading the specification that this cross reference “underscores” that the Patent is not concerned with the avoidance of an interfacial oxide, or indeed any silicon oxide forming at the surface of the silicon substrate.

171    In my view the skilled reader would understand that, if they wished to refer to Ritala, they would gain an understanding of a particular method of performing ALD. The cross-reference can not be expected to provide an insight into the nature of the invention disclosed in the specification as claimed, a point that is perhaps emphasised by the fact that none of the expert construction witnesses gave evidence in chief that, in seeking to understand the disclosure of the patent, they would have gone to Ritala. None described reading Ritala when explaining the disclosure of the patent. Professor Cuevas-Fernandez in his oral evidence considered that reference to it was “not really necessary” to understand the patent or its applicability. Dr Rentsch only went to the Ritala publication in his sixth affidavit, when seeking to rebut a proposition put by Dr Ruby.

172    In context, there is no basis upon which one might assume that the skilled reader would go to the Ritala publication at all when seeking to understand the invention. It provides an “optional extra” for the skilled reader, in the form of a second means by which ALD might be performed. In my view this is a shaky foundation for an argument as to how the invention more broadly disclosed in the patent is to be understood.

173    Accordingly, in my view Ritala cannot be considered helpful in construing the meaning of “a first dielectric layer (3) on a surface of the silicon substrate” whether it is in relation to integer 1(c) or integer 9(c).

174    Finally, I note that the disclosure of the patent repeatedly emphasises that the invention disclosed is for the suppression of surface recombination losses (page 1 line 17 and elsewhere). The purpose of the invention is plainly to aid in the passivation of that surface. The construction that I prefer conforms with the function and purpose of the invention as described in the specification.

175    It is necessary to address a further argument advanced by Hanwha.

176    It contends that reading “depositing … on a surface” as requiring the first dielectric layer to be placed on the crystalline silicon of the substrate places a gloss on the language of the claim by inferring that no intermediate substance or step may be included (such as a thermally grown or natively appearing oxidation). Hanwha submits that this is an impractical approach that is not taught by the specification. In this regard, it submits that as native oxide is difficult to prevent from forming on any crystalline silicon exposed to oxygen and as the prevention of forming of it or its removal is neither taught in the specification nor required in order to achieve a passivation effect, favours its approach to construction ought to be favoured.

177    However, whilst it was known before November 2007 that silicon readily oxidises when exposed to air, such that “native” oxide regions or “islands” may form, it was also known that, in laboratory and also in industrial settings, a silicon wafer was typically cleaned with hydrofluoric acid before the deposition of dielectric layers. In that context, in the Construction JER, the experts agreed that it was not inevitable that the surface of the silicon substrate would be oxidised during the process of manufacturing silicon solar cells. The practice of cleaning is taught in the specification, as noted above, in the passage at page 6 lines 7-13 mentioned above. It was also, I find, part of the common general knowledge to clean the silicon wafer at that stage. Once cleaned, a native oxide would only form on a silicon substrate at a very low growth rate. Whether and how much native oxide grows is, the experts agreed, condition-dependent. Professor Weber gave evidence, in the context of heterojunction cells which were known as at the priority date, that it was possible to have an oxide-free interface, with the consequence that, when reading the patent, “one would not automatically assume that one might always have an oxide at the interface”. I accept that evidence. I do not accept that a person skilled in the art reading the patent would assume that native silicon oxide growth would be an inevitable or even highly likely aspect of the making (whether in the laboratory or as a part of an industrial process) of solar cells using a silicon substrate.

178    There is no suggestion in the disclosure that there exists a pre-formed layer of silicon oxide prior to the deposition of the first dielectric layer.

179    What is more, there is force in the submission advanced by REC Solar that the various alternative arguments advanced by Hanwha run into a difficulty as a matter of logic. If the first dielectric layer may be applied not to the crystalline silicon substrate, but to a silicon substrate that has a layer of silicon oxide on it, one might ask rhetorically: how thick must that silicon oxide layer be before the first dielectric layer is no longer “on the surface”? The answer to that question given by Professor Cuevas-Fernandez and Dr Rentsch was that a 20 nm oxide would not be the “surface” of the silicon substrate but rather would amount to a dielectric layer. However, nowhere in the claims or the specification of the patent are parameters given whereby that thickness may be determined. This suggests that if the construction advanced by Hanwha were accepted, it would leave the scope of the claim unacceptably vague.

180    Finally, I do not consider that Hanwha’s arguments based on the reasoning in Fresenius have merit. The argument advanced is to the effect that the inclusion of additional integers to a claimed combination does not necessarily avoid infringement if those additional integers are properly characterised as inessential or do not make a new working of the combination and all of the essential integers of the claimed combination are present. However, in considering infringement, one must at all times bear in mind that there is no infringement if the patentee has, by the form of the claim, left open what the alleged infringer has done; Fresenius at [49]. The fundamental rule is, as set out in Rodi & Wienenberger AG v Henry Showell Ltd [1969] RPC 367, that there will be no infringement unless the alleged infringer has taken all of the essential features or integers of the patentee’s claim. As the High Court said in Radiation Limited v Galliers and Klaerr Pty Ltd [1938] HCA 17; 60 CLR 36 at 51 and as the Full Court emphasised in Fresenius at [50] in considering infringement, it is ‘the substantial idea disclosed by the specification and made the subject of a definite claim’ (emphasis added) that must be considered.

181    In the present case, I have found that one requirement of the invention disclosed and claimed in claims 1 and 9 is that the first dielectric layer be deposited on the surface of the silicon substrate. That requirement will not be met if a dielectric layer is deposited not on the silicon substrate, but on a layer of silicon oxide (itself a dielectric layer) that lies on the surface of the silicon substrate.

6.4    “second dielectric layer on a surface of the first dielectric layer”; claims 1 and 9

182    Integers 1(d) and 9(e) require that the second dielectric layer be on or deposited “on a surface of the first dielectric layer”.

183    The dispute between the experts is set out in the Construction JER. They agree that the second dielectric layer will be of a material from the list of dielectric materials specified in the patent or another known dielectric material that has been formed (that is, deposited) on the surface of the first dielectric layer, so that the second dielectric layer is furthest from the silicon substrate.

184    The respondents’ construction experts consider that “on a surface” means that there must be “intimate physical contact between the first and second dielectric layer layers with nothing intervening”.

185    Hanwha’s experts do not think that it is necessary to specify that there is nothing intervening and cannot exclude a possible interaction between the two layers, especially upon high temperature annealing forming perhaps a very thin layer whether there is some intermixing between the materials. They accept that they are not aware of such intermixing having been documented.

186    In my view, the words “on a surface” in integer 9(e) should be read consistently with the meaning of the same phrase in integer 1(c) and 9(c), which means that the second dielectric layer is distinguishable from the first by having different composition and properties and is situated on the outer surface of the first layer comprising aluminium oxide. There can be no other layer or intervening material between the first and second dielectric layers.

6.5    “first dielectric layer comprising aluminium oxide”; claim 9

6.5.1    The submissions

187    Hanwha contends that the phrase “comprising aluminium oxide” should be construed to mean “substantially” aluminium oxide because the word “comprising” is used in an inclusive sense in the claims and also because the specification contemplates that the layer comprising aluminium oxide may contain an unspecified proportion of other molecules.

188    REC Solar agrees that the word “comprising” should be understood inclusively, but subject to the limitation that the first dielectric layer must be made up of “substantially aluminium oxide” meaning that the layer is “nearly completely” composed of aluminium oxide with no, or very few, other elements. This, it submits, satisfies the requirement that the first dielectric layer have the character of aluminium oxide albeit with some contaminants in it.

6.5.2    Consideration

189    In the Construction JER the experts agreed that the first dielectric layer on the surface of the silicon substrate “should be composed substantially of aluminium oxide”. Professor Cuevas-Fernandez explained (with the other experts agreeing) “substantially” means that it contains mostly aluminium oxide, with the layer having no, or few, contaminants or other elements present. A technical reason given for this by Dr Glew is (in relation to equivalent words in claim 1) that, in the context of ALD, there would typically be other or residual impurities or intermixing.

190    In my view there can be little doubt that the word “comprising” within integer 9(d) should be understood in an inclusive sense. Indeed, the parties agreed that this is so. In the specification “comprise” or “comprising” are used several times. On page 4 line 11 the usage is equivocal (“the first dielectric layer comprises aluminium oxide”), on page 6 line 18 it is used inclusively (“silicon substrate is firstly flushed with an aluminium-containing compound comprising at least one of” a number of components). It is also used inclusively on page 8 line 10 (“second dielectric layer comprises silicon nitride, silicon oxide und/or [sic] silicon carbide”). In broadly describing the second aspect of the invention, the specification is in one part on page 9 line 27 undoubtedly used in an inclusive sense (“a solar cell is proposed comprising a silicon substrate”) and then used in line 28 in the same sense as is presently under consideration (“a first dielectric layer comprising aluminium oxide on a surface of the silicon substrate”). In claim 1 it is used in the same sense as under present consideration. In claim 2 it is used inclusively (“comprising at least one of the components [listed]”) in the same way as on page 6 line 18 of the specification. In claims 3, 11, 14 and 20 it is used equivocally.

191    Hanwha relies on the passage at page 7 lines 13-14 which provides that “[a] layer is then formed that at least contains Al₂O₃ molecules that preferably consists entirely of Al₂O₃ molecules” which it submits contemplates that the first dielectric layer is not made entirely of such molecules. Indeed, in his evidence, Professor Weber considered that it would be impossible that it do so.

192    In my view any ambiguity surrounding the usage in integer 9(c) is best resolved by construing the word “comprising” consistently within claim 9 and by having regard to the expert evidence. The term is plainly used inclusively in integer 9(a), because a solar cell will not consist entirely of the dielectric stack described – it will include at least electrodes and other materials. One would typically understand the same word to be used in the same way throughout the claim. Furthermore, nothing in the specification suggests that a different approach must be taken. References to the term are either clearly inclusive, or ambiguous. None, in context, clearly indicate that it is being used to mean “consists of”. Indeed, as I have noted, the expert evidence suggests that it is impossible.

193    Accordingly, I accept that the word “comprising” in claim 9 should be understood in an inclusive sense. In order to have the character of being a dielectric layer “comprising aluminium oxide” I accept the evidence of the experts that such layer must be made up substantially of aluminium oxide. Although “comprising” could be taken to mean simply including, having regard to the disclosure of the specification and the evidence of the experts, I do not consider that the integer will be met if a proportionately small amount of aluminium oxide is present. The layer must substantially be made up of that substance, albeit that other materials may also be included within it.

6.6     “… and hydrogen being embedded into the second dielectric layer”; claim 9

194    In claim 9, the solar cell includes (emphasis added):

(e) a second dielectric layer (5) on a surface of the first dielectric layer (3), (f) the materials of the first and second dielectric layer differing (g) and hydrogen being embedded into the second dielectric layer.

195    There is a dispute as to the correct construction of the emphasised words in integer (g).

6.6.1    The arguments

196    Hanwha contends that the integer should be construed as requiring hydrogen to be present in the second layer “at deposition”, meaning before any firing step, in a form enabling its release during a subsequent high-temperature firing step. It submits that the purpose of the hydrogen being embedded is to act as a source of hydrogen for interface passivation during the subsequent firing step, and so hydrogen must be present in a form that enables it to be released at that point. REC Solar contends that the requirement that there be hydrogen “embedded into the second dielectric layer” should be construed as requiring that hydrogen simply be present in the second dielectric layer.

6.6.2    Consideration

197    The language of claims 1 and 9 requires that the materials of the second dielectric layer differ from those of the first, and hydrogen be “embedded into” the second. The word “embedded” has no special or technical meaning to those in the field. In the Macquarie Dictionary, it is defined to mean “to fix firmly in a surrounding mass” or “to lay in or as in a bed”.

198    In the Construction JER the construction experts agreed that the requirement of “hydrogen embedded” would be met by a certain amount of hydrogen being “contained in” the second layer in the as-deposited state before “firing”.

199    In describing the method aspect of the invention on page 5 lines 10-16, one part of the “key” to understanding the outstanding passivating effect and tempering stability of the stack layer according to the invention which is produced using the ALD process, and “the highly hydrogenous SiO_x, SiN_x or SiC_x layers”, which are formed during the PECVD process, is said to be that:

… A part of the hydrogen from the PECVD-deposited layers can diffuse through the ultrathin Al2O3 layer and passivate unsaturated silicon bonds at the interface to the silicon.

200    As this passage states, this embodiment concerns the deposition of the first layer by ALD and the second layer by PECVD.

201    Later, at page 8 lines 12-14, the specification notes that in another embodiment dielectric layers made of silicon nitride, silicon oxide and/or silicon carbide “can contain a high hydrogen content; this can help to further passivate the solar cell”. A similar observation is made in the next paragraph.

202    The specification at page 9 lines 4-12 provides:

According to one embodiment of the method according to the invention, a high-temperature step is carried out at temperatures above 600 °C, preferably above 700 °C and more preferably above 800 °C, after the depositing of the second dielectric layer. A high-temperature step of this type can for example be used to fire, during further processing of the solar cell, metal contacts, which were printed beforehand onto the solar cell surface by means of screen printing, into the solar cell. The high-temperature step can in this case have the further advantage that hydrogen contained in the second dielectric layer can easily diffuse at the elevated temperatures through the first dielectric layer and saturate bonds of the silicon that are still free; this can lead to a further improvement in the passivating effect.

(Emphasis added.)

203    A similar point is made in the final paragraph of the specification, where it is observed that where thin layers made of silicon oxide, silicon nitride or silicon carbide are deposited by means of PECVD, they have a very high hydrogen content (for example, greater than 5 at.%) and “therefore serve as a source of hydrogen during a firing step in the temperature range of 700-900 °C (page 14 lines 7-11):

The hydrogen diffuses through the ultrathin Al₂O₃ layer and passivates unsaturated silicon bonds (“dangling bonds”) at the Si/Al₂O₃ interface, leading to a very good surface passivation after the firing step. In this way, the combination according to the invention of the two known deposition methods, ALD and PECVD, allows the formation of a firing-stable passivating layer which is optimally suitable for solar cells.

204    However, it may be noted that claim 1 makes no reference to a method that involves a subsequent firing step or, indeed, any means by which the second dielectric layer is formed. In dependent claim 4, PECVD is identified as the method. However, it is not until dependent claim 6 that a high-temperature step is added as an integer at temperatures above 600 °C and most preferably above 800 °C after depositing of the second dielectric layer.

205    It is apparent that in the discourse of the patent not all embodiments of the method disclosed necessarily include a high temperature firing step. The language of claim 1 does not require a subsequent firing step to take place. It may, or it may not. As noted, it is not until the invention the subject of claim 1 is narrowed by the dependency provided in claim 6 that this becomes a requirement.

206    In claim 9, the same language of “hydrogen being embedded into the second dielectric layer 1” is used in integer 9(g). However, unlike claim 1, claim 9 is not a method claim but a claim for a product, being a solar cell including a second dielectric layer which has hydrogen “embedded”. On its face, this is a requirement that hydrogen merely be present in the second dielectric layer in the completed product. Hanwha’s construction seeks to distort this language by adding a qualification that hydrogen must be found to have been present before any firing step in a form enabling its release during a subsequent firing. Whilst this may make sense in the context of a sequential method, it does not make sense for a product claim. This gives rise to a problem in understanding why the patentee chose to use this language. The experts gave evidence that the purpose of embedded hydrogen is to act as a source of hydrogen for interface passivation during a subsequent firing step. They said in the Construction JER at [34] in relation to claims 1 and 9:

The description of the embodiments of the claims makes clear the purpose of the H that must be ‘embedded’ according to these claims, which is to act as a source of H for interface passivation during the subsequent firing step. However, claims 1 and 9 by themselves don’t give us enough information to decide when ‘embedded’ is met. Nevertheless, claim 5 clarifies that the hydrogen content should be preferably greater than 5%, and says that as a minimum it should be 1%. The requirement of “hydrogen embedded” would be met, according to the Patent, by dielectric materials in the second layer that contain more than 1% hydrogen in the as-deposited state, that is, before “firing”.

207    To the extent that this passage tends to fuse the teaching of the specification and the requirements of the claims, it must be set aside. Expert evidence, even when the subject of agreement, does not bind the Court on questions of construction. Claims 1 and 9 do not provide sufficient “information” because they contain no limitation as to what amount of hydrogen must be embedded. Nor is claim 1 limited to a method which involves the use of a firing step. That is apparently because, in the discourse of the patent, such a step is not necessary in order to achieve the “key requirement” of the invention that part of the hydrogen from the PECVD-deposited layers can diffuse through the ultrathin Al₂O₃ layer and passivate unsaturated silicon bonds at the interface to the silicon. Indeed, the teaching of the specification is not that embedded hydrogen only has utility when there is a subsequent firing step. To the contrary, several embodiments require the presence of hydrogen in the second dielectric layer without reference to a subsequent firing step.

208    Accordingly, whilst the skilled reader might understand that hydrogen may be embedded in a form to act as a source during a subsequent firing step, that is neither the exclusive teaching of the specification nor a requirement of claim 9.

209    Some additional points should be made in relation to claim 9, which is for a solar cell rather than a method of making a solar cell.

210    The construction propounded by Hanwha requires that the integer contains two limitations absent from the language of the claim: first that the second dielectric layer include hydrogen at a point prior to its completion as a solar cell, being before the firing step; and secondly that the hydrogen be available in a form and amount enabling its release to enable subsequent passivation of the silicon surface.

211    Neither limitation is apparent from the language of the claim. The principles of patent construction do not extend to enable an imputed purpose for an integer to distort the plain language of the claim. In relation to the first, claim 9 is for a completed solar cell. If a firing step is involved in making the solar cell, the question of whether hydrogen is embedded is to be considered by having regard to the second layer in that completed product.

212    In relation to the second, Professor Weber explained that the amount of hydrogen contained in the second dielectric layer will differ before and after the firing step, because when a high temperature is applied during the firing step (typically at a maximum temperature of about 900 °C), the hydrogen becomes mobile and can diffuse out of the film. Accordingly, in the solar cell of claim 9, there will be only residual hydrogen remaining in the second dielectric layer after the firing step. He says:

As at November 2007, I was not aware of any purpose served by any residual hydrogen remaining in a dielectric layer after the firing step. However, I would consider that a natural consequence of effective passivation of the silicon/Al₂O₃ interface by hydrogen following the firing step would be that a certain amount of hydrogen remains in the second dielectric layer. I note that claim 9 does not require a specific amount of hydrogen to be “embedded into the second dielectric layer”. In my view, claim 9 encompasses a second dielectric layer which has minimal hydrogen embedded in it following the completion of the solar cell (including the completion of the firing step). …

(Emphasis added.)

213    Professor Weber was not challenged in cross-examination on this passage, which he referred to again in his oral evidence. I accept it as correct.

214    In my view, the meaning of “embedded” is to be understood as meaning simply “fixed or lying in a surrounding mass”. In the context of claim 9, that requires hydrogen to be present in the second dielectric layer. I reject the submission that “embedded” within claim 9 contains within it a requirement that hydrogen be confined to any particular form or amount. That construction tends to elevate what Hanwha imputes to be the purpose of the claim over the plain language used in it. One simply cannot construe claim 9, which is for a “solar cell” – being a completed product – by reference to the presence of hydrogen in a layer prior to the completion of that product.

6.7    “… substantially atomically tight”; claim 10

215    Claim 10 provides for a solar cell product according to claim 9 “wherein the first dielectric layer is deposited by means of atomic layer deposition, so that it is substantially atomically tight” (emphasis added). There is no dispute that this means “nearly complete coverage with no, or very few, uncovered areas or holes, even for very thin layers that are only a few atomic layers thick”.

6.8    “… second dielectric layer comprises silicon nitride”; claim 11

216    Claim 11 is for a solar cell according to claim 9 or 10 “wherein the second dielectric layer comprises silicon nitride” (emphasis added).

217    Hanwha contends that this means that the second dielectric layer “contains” silicon nitride. REC Solar contends, that for a second dielectric layer to comprise silicon nitride, it should be composed substantially of silicon nitride with no or very few contaminants or other elements present.

218    I have in section 6.5 addressed the meaning of “comprises” in the context of the claims. In my view it is also used in the inclusive sense in claim 11. Furthermore, the specification teaches at page 8 that “the second dielectric layer comprises silicon nitride, silicon oxide und/or [sic] silicon carbide” and at page 13 that the method proposed for forming a stack layer will include a “silicon containing thin layer” thereby indicating that the layer must contain the substituent identified but many include more than one. In my view, just as integer 9(c) requires that the first dielectric layer be substantially made up of aluminium oxide, claim 11 requires the second dielectric layer to be substantially made up of silicon nitride.

6.9     “… wherein the surface of the silicon substrate is passivated by hydrogen”; claim 16

219    Claim 16 is for a solar cell “according to any one of claims 9 to 14, wherein the surface of the silicon substrate is passivated by hydrogen” (emphasis added). As I have noted earlier, a hydrogen atom is able to passivate the surface of a silicon substrate by donating electrons to fill dangling bonds at that surface.

220    There is no requirement in claim 16 that the surface of the silicon substrate is passivated by hydrogen that is embedded in the second dielectric layer (which may have diffused following a high temperature step); passivation by hydrogen, irrespective of its provenance, will satisfy the language of claim 16.

221    Furthermore, the claim does not specify that any particular degree of passivation is required. Nor, as the experts agree, does the claim require that the silicon substrate solely be passivated by hydrogen.

6.10    “…second dielectric layer forms part of a back surface reflector”; claim 19

222    Claim 19 is for a solar cell according to claim 18 wherein the second dielectric layer forms part of a back surface reflector.

223    The expert evidence demonstrates that the expression “back surface reflector” is a term of art. The experts agreed that it refers to “a layer or group of layers at the back of a solar cell that reflects light back into the interior of the solar cell”.

224    REC Solar submits nonetheless that claim 19 requires a layer to reflect not just any light, but rather all or close to all of the light, as it would if a metal coating was present, in order to constitute a “back surface reflector”. They derive this construction from a passage in the specification which provides, in relation to the first aspect of the invention, that the surface of the silicon substrate that is to be coated with the dielectric layers of the invention may be placed at the back, remote from the incident light during use, and that in this case “the second dielectric layer is embodied preferably as what is known as a back surface reflector, so that light, in particular infrared light, which penetrates the entire solar cell, is for the most part reflected at this back surface and thus passes through the solar cell substrate a further time” (emphasis added). REC Solar submits that the construction experts did not appear to have this passage in mind when they construed claim 19 and that in their oral evidence each of Professor Cuevas-Fernandez, Dr Rentsch and Dr Ruby agreed that the term “back surface reflector” was a term used to refer to a reflector that reflects all or close to all of the light or, as Professor Weber said, at least be optimised to some extent to maximise reflection of back light.

225    The difficulty with the submission advanced by REC Solar is that it is not supported by the language of claim 19, which simply requires that the second dielectric layer form part of the solar cell that reflects light back into the interior of the cell. No doubt some, if not all, back surface reflectors have a degree of optimisation. However, the language of the claim does not require that. I reject the submission that claim 19 requires a layer to reflect not just any light, but rather all or close to all of the light.

7.    INFRINGEMENT – THE CASE AGAINST REC SOLAR

7.1    The infringement allegations

226    When Hanwha commenced the proceedings, it alleged that each of the three groups of respondents has infringed the patent by exploiting solar modules containing Passivated Emitter and Rear Cell (PERC) cells. After settlements were reached with LONGi and Jinko, the remaining infringement case lies against REC Solar.

227    Hanwha contends that each of eight solar cells infringe asserted claims 12-14 and 16-21 of the patent, being the Vina, Sing, Solartec, NSP, MS, MMS, MV and U cells (REC cells).

228    The defence to the infringement case advanced by REC Solar is that, subject to the question of validity, none of its impugned products contains all of the features of any of the claims asserted against it.

229    Hanwha advances its case on the basis of a confidential product description that provided a description of each of the Solartec, NSP, Vina and Sing cells and a supplementary product description that provided a description of each of the MS, MMS and MV cells. It additionally relies on a report of experiments performed by representatives of Sydney Microscopy and Microanalysis at the University of Sydney concerning the composition of the U cell.

230    REC Solar seeks to supplement the content of the product description and the supplementary product description by adducing in the evidence of Dr Glew additional analysis of the REC cells that adds additional detail, not provided in the product descriptions. REC Solar submits that this additional information provides further reasons as to why the REC cells do not infringe the asserted claims. However, Hanwha makes no submission that the additional information provided by Dr Glew would provide any further or other basis upon which it would establish infringement.

231    For the reasons set out below, I have formed the view that essential integers in claim 9, upon which all of the asserted claims depend, are absent in each of the REC cells. Accordingly, Hanwha has failed to establish infringement on the basis of the case that it advances. In those circumstances, it is unnecessary for me to address the additional points raised by reference to the further materials identified by Dr Glew.

7.2    The evidence

232    The product description and the supplementary product description were annexed to affidavits provided by Dr Shankar Gauri Sridhara, the chief technology officer of REC Solar Pte Ltd, who verified that the product descriptions provided a “true and complete description of the REC Solar Solar Modules”. Dr Sridhara also annexed primary source and contemporaneous documents referred to and relied upon in the product descriptions, and deposed to being personally acquainted with the facts to which they relate.

233    No product description was given of the U cell but information as to the constitution of that product was provided by a report of experiments performed by representatives of Sydney Microscopy.

234    Jae Sung Lee, an R&D researcher at REC Solar, gave additional evidence about reports prepared by Wintech, who provided information contained in product descriptions.

235    Dr Rentsch and Dr Glew gave expert opinion evidence relevant to the question of infringement, prepared a joint expert report and gave oral evidence on that subject.

236    In his expert evidence, Dr Glew relied on evidence used in EDS line profiles for each of the NSP, Solartec, Sing, Vina and MV cells which was different to that set out in the product description and supplementary product description. To the extent that in doing so REC Solar seeks to resile from the content of the product description and supplementary product description, I would not permit that course. It is contrary to the manner in which the case was conducted. However, as I have noted, Hanwha’s infringement case fails on the basis of the case advanced in the product description and supplementary product description, and it is not necessary to address the point further.

7.3    The impugned REC cells

7.3.1    Introduction

237    Based on the information in the product description and the supplementary product description each of the REC cells:

(1)    is a PERC solar cell;

(2)    includes a p-type silicon substrate;

(3)    has dielectric layers that were deposited by PECVD;

(4)    has a number of metal contacts located on the rear surface of the solar cell which extend through the dielectric layers at the rear of the cell; and

(5)    has a back surface reflector.

238    There is no dispute about the matters in (1)-(5).

239    The product description and the supplementary product description provide relevant information based either on testing conducted internally or on testing conducted by WinTech NanoTechnology Services Pty Ltd of the cells using HT-Transmission electron microscopy (HT-TEM), scanning transmission electron microscopy (STEM) and energy-dispersive x-ray spectroscopy (EDS). I turn now to consider the relevant characteristics of the REC cells.

7.3.2    Solartech cell

240    The Solartec cell was tested by WinTech.

241    An EDS Analysis identified the concentration of oxygen (pink), aluminium (blue), silicon (green) and nitrogen (orange) as a function of depth in nm as set out below:

[REDACTED]

242    After referring to the STEM analysis and providing various images produced from it, the product description confirms that, using the PECVD technique, at least three layers are formed on the rear side of the silicon wafer, which are depicted in Figure 5 (the layer schematic) as follows:

243    The analysis provides that the thickness of the silicon oxide layer is about 1-2 nm, the thickness of the aluminium oxide layer is about [REDACTED] and the silicon nitride layer is about [REDACTED].

244    The product description provides the following schematic diagram of the Solartec cell, where the “H” letter represents hydrogen atoms:

7.3.3    NSP cell

245    The NSP cell was also tested by WinTech.

246    An EDS Analysis identified the concentration of oxygen (pink), aluminium (blue), silicon (green) and nitrogen (orange) in Figure 7 which was similar in overall appearance to Figure 3, albeit with different figures as follows:

[REDACTED]

247    After referring to the STEM analysis and providing various images produced from it, the product description confirms that, using the PECVD technique, at least three layers are formed on the rear side of the silicon wafer, which are depicted as in the layer schematic above for the Solartec cell and the overall arrangement is the same as in the schematic diagram above for the Solartec cell.

248    The layer thicknesses are measured in the product description as silicon oxide layer being about 1-2 nm, the aluminium oxide layer as about [REDACTED] and the silicon nitride layer as about [REDACTED].

7.3.4    Vina cell

249    The Vina cell was tested by WinTech using STEM and EDS. The EDS Analysis was broadly similar to that depicted in the layer schematic and schematic diagram (reproduced above) for the Solartech and NSP cells. The product description observes again that at least three layers are depicted in the layer schematic and the overall look of the product is the same as in the schematic diagram.

250    The product description reports that the thickness of the silicon oxide layer is about 1-2 nm, the aluminium oxide layer is about [REDACTED] and the silicon nitride layer is “presently unknown”.

7.3.5    Sing Cell

251    The Sing cell was tested by WinTech using secondary ion mass spectrometry (SIMS), transmission electron microscopy (TEM), EDS and electron energy loss spectroscopy (EELS). An EDS line profile was reproduced which identifies the concentration of oxygen (pink), aluminium (orange), nitrogen (green) and silicon (blue) as a function of depth in nm as follows:

[REDACTED]

252    The product description observes again that at least three layers are depicted in the layer schematic and the overall look of the product is the same as in the schematic diagram. It reports the thickness of the layers being: silicon oxide about 1-2 nm; aluminium oxide about [REDACTED] and silicon nitride about [REDACTED].

7.3.6    Mono Sing Cell    

253    The supplementary product description reports that the Mono cell was tested by WinTech using STEM and EDS.

254    The concentration of oxygen (pink), aluminium (orange), silicon (blue) and nitrogen (green) as a function of depth in nm was depicted as follows:

[REDACTED]

255    The supplementary product description observes again that at least three layers are depicted in the layer schematic and the overall look of the product is the same as in the schematic diagram. The layer thicknesses are reported to be: silicon oxide about 1-2 nm; aluminium oxide about [REDACTED] and silicon nitride about [REDACTED].

7.3.7    MMS cell

256    The supplementary product description reports that the MMS cell was tested by WinTech using STEM and EDS and provides the following EELS profile identifying the concentrations of oxygen (pink), aluminium (orange), silicon (blue) and nitrogen (green) as a function of depth in nm:

[REDACTED]

257    The supplementary product description observes again that at least three layers are depicted in the layer schematic and the overall look of the product is the same as in the schematic diagram. The layer thicknesses are reported to be: silicon oxide about 1-2 nm, aluminium oxide about [REDACTED] and silicon nitride about [REDACTED].

7.3.8    MV cell

258    The supplementary product description reports that the MV cell was tested by WinTech using aberration-corrected scanning transmission electron microscopy (AC-STEM) and EELS which generated the following profile identifying the concentrations of oxygen (green), aluminium (dark blue), silicon (red) and nitrogen (light blue) as a function of depth in nm:

[REDACTED]

259    The supplementary product description observes again that “at least” three layers are depicted in the layer schematic and the overall look of the product being the same as in the schematic diagram. The layer thicknesses are reported to be: silicon oxide about 1-3 nm; aluminium oxide about [REDACTED] and silicon nitride about [REDACTED].

7.3.9    The U Cell

260    The U cell was tested by Sydney Microscopy using STEM and EDS concerning the composition of the U cell report generated the following profile identifying the concentrations of oxygen (green), aluminium (dark blue), silicon (red) and nitrogen (light blue) as a function of depth in nm:

261    Based on interpreting experiments performed by representatives of Sydney Microscopy, the expert evidence indicates that the U cell includes a silicon substrate, a silicon oxide region, a dielectric layer comprising aluminium oxide and a dielectric layer comprising silicon nitride. I find that the silicon oxide region forms a layer of about 2.5 nm, an aluminium oxide layer of about 20-40 nm and a silicon nitride layer of over 120 nm.

7.4    General findings

262    I find that in each of the REC Solar products there exists a silicon oxide layer lying between the crystalline silicon substrate and the aluminium oxide layer. The layer is not part of the silicon substrate, but a dielectric layer. As Dr Rentsch and Dr Glew agreed, it is not a native oxide layer, but an interfacial oxide layer which is not relevantly different in character from a thermally grown oxide.

7.5    Infringement of claim 9

263    It will be recalled that claim 9 is as follows:

9. (a) Solar cell comprising: (b) a silicon substrate (1): (c) a first dielectric layer (3) comprising aluminium oxide on a surface of the silicon substrate (1)(d) wherein the first dielectric layer has a thickness of less than 50nm, preferably less than 30nm and more preferably less than 10nm; (e) a second dielectric layer (5) on a surface of the first dielectric layer (3), (f) the materials of the first and second dielectric layer differing (g) and hydrogen being embedded into the second dielectric layer.

7.5.1    Hanwha’s submissions

264    Hanwha submits that, at the point in time when the aluminium oxide is deposited, some parts of the silicon surface are likely to have been oxidised through the formation of a native oxide, but the surface has not been subject to a step that forms a more regular oxidised surface. It submits that REC Solar is “not sure at what point” the silicon oxide region identified in each of its products is created within the cells, referring to the evidence given in cross-examination by Dr Sridhara, and that the Court should find that the silicon oxide region is an interfacial oxide that is formed during the manufacture of the cell, in particular, during the post-deposition heating or annealing processing steps. It submits that if the Court finds that the REC cells’ structure is as set out in the diagrams contained in section 7.3, then:

(a)    On its primary construction, the silicon oxide layer forms part of the surface of the silicon substrate in the REC cells;

(b)    On its alternative construction, the dielectric layer comprising aluminium oxide is “on a surface” of the silicon substrate notwithstanding the very thin silicon oxide layer. The silicon oxide layer is not a “dielectric layer” let alone “a first dielectric layer”; and

(c)    In any event, its argument based on Fresenius leads to the conclusion that the combination claimed in claim 1 is infringed.

7.5.2    Consideration

265    The question of infringement turns primarily upon whether in the REC Solar products the requirement of integer 9(c), which is that a first dielectric layer comprising aluminium oxide is “on a surface of the silicon substrate”, is met.

266    I have in section 6 of these reasons rejected each of the three alternative construction arguments propounded by Hanwha.

267    Claim 9 is a product claim for a silicon solar cell that includes “a first dielectric layer comprising aluminium oxide on a surface of the silicon substrate” (integer 9(c)). Regardless of how the particular REC cells are manufactured, taking Hanwha’s case at its highest, in each there is a silicon oxide layer of about from 1-2 nm thickness. The means by which it is formed is not relevant to consideration of claim 9, which concerns the presence or absence of the layer in the product as claimed.

268    Having regard to the proper construction of claim 9, I find first, that Hanwha has not established that in any of the REC cells there is a dielectric layer comprising aluminium oxide “on a surface of the silicon substrate” as integer (c) of claim 9 requires. The silicon oxide layers are, as Dr Rentsch said, “different to a silicon substrate”.

269    Secondly, in relation to Hanwha’s argument based on the decision in Fresenius, I do not accept that the very thin silicon oxide layer present in the REC cells does not provide any relevant surface passivation. In this regard, the experts agreed that a very thin dielectric layer is likely to contribute some passivation in the context of a stack of dielectric layers. As I have noted earlier, as much was accepted by Professor Cuevas-Fernandez and Dr Rentsch. Accordingly, the REC cells products may be said to have a three layered stack, which may be characterised to be a different combination to that which is the subject of the claims and a different product to that which is taught in the patent.

270    Put another way, Hanwha, which bears the onus on infringement, has not demonstrated that even the single layer of silicon oxide in the REC cells products does not by itself produced a passivating effect. Accordingly, were I to be incorrect in my understanding of the effect of the parts of Fresenius to which Hanwha refers, I would not accept the submission that the REC cells do not result in a new working of the combination within Fresenius at [70].

271    Thirdly, Hanwha has not established that the aluminium oxide layer in the REC cells is a “first dielectric layer” as integer 9(e) of the claim requires. In this regard, I am satisfied that even a very thin layer of silicon oxide is a “dielectric layer” within claim 9, with the consequence that, at best, the aluminium oxide layer in the REC cells is a second dielectric layer. It is not necessary for this purpose to explore the additional layers contended for by Dr Glew.

272    As a consequence of these findings, in my view none of the REC cells infringe claim 9 or any claim dependent on claim 9. However, I do note that disputed integer 9(g), which requires that hydrogen be embedded into the second dielectric layer, is present in the REC Solar cells. This follows from my construction of this integer and my acceptance of the expert evidence that hydrogen will be present following deposition of the silicon nitride layer by the use of a PECVD process, even after the high temperature firing step has been completed. In this regard, although REC Solar has not admitted that PECVD is used in the manufacture of the U cells (it does admit its use for the other cells), I accept, on the balance of probabilities, the evidence of Dr Rentsch that this process was used, first, because this is the only known process utilised for the creation of silicon nitride layers on an industrial scale and, secondly, because of the evidence of characteristic bands or striations across the layer which Dr Rentsch considered were typical of the use of such a method.

273    Nonetheless, because of the absence of two essential integers required in claim 9 from each of the REC Solar products, neither claim 9 nor any of the asserted claims (each of which is dependent on claim 9) is infringed.

7.6    Infringement of claim 11

274    Claim 11 additionally requires that the second dielectric layer comprises silicon nitride. Given that in each of the REC Solar products the first dielectric layer is silicon oxide and the second dielectric layer is aluminium oxide, this integer of the claim is also absent.

7.7    Infringement of claim 13

275    Hanwha accepts that none of the Sing, MS and MMS cells infringe claim 13 because, regardless of any other point, the thickness of the silicon nitride layer is greater than 100 nm. Although it is otherwise disputed, however, I accept that the U cell has a silicon nitride layer within the claim.

7.8    Infringement of claim 16

276    Claim 16 is dependent on claims 9 to 14 and adds to these claims an integer “wherein the surface of the silicon substrate is passivated by hydrogen”. The evidence indicates that when silicon nitride is formed by PECVD, it is rich in hydrogen. When the solar cell is subjected to high temperatures – such as the firing step used in the manufacture of the REC Solar cells – hydrogen in the silicon nitride disperses throughout it. Upon reaching the silicon substrate, the evidence indicates that hydrogen will provide passivation.

277    Claim 16 when dependent on claim 9 or claims 12, 13 or 14 is to a completed product. The only requirement of the claim is that the surface of the silicon substrate be passivated by hydrogen. There is no limitation as to where or how hydrogen may have reached the surface, although the evidence indicates that where PECVD is used, it is likely to have emanated from the hydrogen-rich layer of silicon nitride applied using that process.

278    I accept the evidence of Dr Rentsch (and, in the context of consideration of the novelty disclosures, Dr Weber) that, when silicon nitride is deposited in this way, hydrogen disperses throughout the solar cell, providing passivation. I also accept, on the balance of probabilities, that this occurred in each of the REC Solar products. This conclusion conforms with Dr Sridhara’s understanding that hydrogen passivates the surface of the silicon substrate. Accordingly, the additional integer required by claim 16 is present.

7.9    Summary of conclusions in relation to infringement

279    For the reasons set out above, I find that none of the REC Solar products infringes claim 9, with the consequence that none of the asserted claims is infringed.

280    To the extent that the integers of dependent claims 11, 13 and 16 remain relevant, I find that the integers in claim 11 are not possessed by the REC Solar products, that for claim 13 all but the Sing, MS and MMS cells possess the additional integer in that claim, and that all of the REC Solar products possess the additional integer of claim 16.

8.    THE ACL CASE

281    Hanwha has accepted that the ACL cause of action stands or falls on the patent infringement case. As a consequence of my finding that the infringement case fails, the ACL case must be dismissed.

9.    LACK OF INVENTIVE STEP

9.1    Introduction

282    REC Solar pleads its lack of inventive step case in two forms. First it contends that the invention claimed in the challenged claims lacks an inventive step taking the common general knowledge together with either Hoex 2006 or 2007 before 14 November 2007. Secondly, it contends that the invention in the challenged claims lacks an inventive step considering Hoex 2006 and Hoex 2007 in combination. In closing submissions, REC Solar did not rely on the second form of the pleaded case and I do not address it further.

283    REC Solar’s evidence in chief in relation to the question of lack of inventive step was supplied by Professor Weber to which Hanwha responded in detail with an affidavit from Professor Cuevas-Fernandez. Hanwha also relies on an affidavit affirmed by Dr Winderbaum, who addressed the Hoex publications, but did not consider the question of lack of inventive step or respond to Professor Weber’s evidence and was not shown the patent.

284    As I have noted, the parties cooperated to produce the statement of agreed common general knowledge, an edited form of which is included as Annexure A to these reasons. The inventive step joint expert report (IS JER) yielded additional agreement as to parts of the common general knowledge.

285    In their closing submissions REC Solar provides an executive summary of the pathway that, in its submission, sets out how it may be concluded that the invention claimed in the patent is obvious to the person skilled in the art in the light of Hoex 2006, which is their primary case. It has provided a similar summary in respect of Hoex 2007, although its reliance on that document is secondary to Hoex 2006. Accordingly, in these reasons I first consider the Hoex 2006 pathway.

286    The pathway is said to lead the skilled team to the invention, two versions of which are identified by Professor Weber in his first affidavit as structures 1 and 2, to which I refer below.

287    I have found in Section 5.4 above that the person skilled in the art may be considered to be a team comprising persons who are researchers working in academic institutions focussed on the development of photovoltaic cells in the context of solar cell design working in collaboration with persons in industry who are engaged in the manufacture of solar cells. Each of Professors Weber and Cuevas-Fernandez and Dr Winderbaum are sufficiently qualified by their training and experience to assist the Court in understanding the approach of the hypothetical skilled team.

288    REC Solar contends that in the light of the common general knowledge and Hoex 2006 the following pathway to the conclusion of obviousness may be traced:

(1)    In the years prior to November 2007, developing an industrially viable PERC cell had been a subject of ongoing research interest which was also relevant to industry participants, as it was considered that PERC cells (having a passivated rear surface as well as the conventional front surface) would likely be the next generation of solar cells, taking a step forward in efficiency [step 1];

(2)    Research into suitable materials to be used for passivating the rear of the PERC cell had demonstrated significant obstacles for the commonly used passivating materials, silicon oxide (which caused multi-crystalline wafer degradation) and silicon nitride (which caused parasitic shunting on the p-type surface at the rear of the wafer). These were matters of common general knowledge [step 2];

(3)    In Hoex 2006, Bram Hoex made an important contribution to the development of PERC cells by “rediscovering” the use of aluminium oxide as a passivating layer, demonstrating its excellent passivating qualities in ultrathin layers deposited by atomic layer deposition on a p-type surface and suggesting its use on the rear surface of a PERC cell. Hoex 2006 would have been and was ascertained by those working in that field [step 3];

(4)    Implementing that suggestion would have involved, as a matter of priority, testing the firing stability of the aluminium oxide layer. That testing would have shown that aluminium oxide was not firing stable, and that it was reasonable to attribute this, at least in part, to a low of hydrogen at the interface on firing [step 4];

(5)    That consideration would have led to proposing PECVD silicon nitride (as preferred by Professor Weber) or PECVD silicon oxide (as preferred by Professor Cuevas-Fernandez) as a capping layer, both of which were hydrogen reservoirs, though silicon nitride was better known and industrially adopted for this purpose. Determining whether they were acceptable would have involved experimentation, but of a well-known and routine kind [step 5];

(6)    The process of atomic layer deposition at the relevant time was not immediately industrial applicable in terms of its level of throughput. But a solar cell having an ALD aluminium oxide and PECVD silicon nitride or silicon oxide stack as proposed by Professors Weber and Cuevas-Fernandez was nevertheless even prior to undertaking the work to improve the throughput level of ALD techniques, an “industrially viable” solar cell. The patent uses that term (page 4, line 3) to describe the method and solar cell which it claims, and the claims contain no requirements of the ALD technique in terms of deposition times, throughput requirements or immediate industrial applicability. The witnesses agreed that, in implementing the patent, considerable work, perhaps over many years, would have been required to achieve industrially acceptable throughput, but they would expect that it could be done. In that context, an industrially viable method and cell of the kind claimed by the patent does not mean “immediately industrially applicable” but rather means a cell which is industrially “feasible” in the sense that it could be made in a research setting and it could be expected that, with sufficient implementation work, it could be made industrially applicable. It follows that the question of the work required to achieve immediate industrial applicability is not relevant because it travels beyond the invention as claimed [step 6].

289    REC Solar traces through each of steps (1) to (6) in its submissions. It proffers a slightly different analysis for their alternative case based on Hoex 2007, which I address separately.

290    Hanwha challenges this pathway on several levels. It contends that the work and experimentation that this pathway leaves to the person skilled in the art is antithetical to a conclusion of obviousness; that the common general knowledge does not support the propositions in steps (1) and (2) and that there was in fact no motivation to pursue work on PERC cells before November 2007; that Hoex 2006 would not have been ascertained or regarded as relevant within the then requirements of s 7(3) of the Patents Act, and; that even if the person skilled in the art were legitimately able to supplement the common general knowledge with Hoex 2006, REC Solar’s reliance on “structure 1” or “structure 2” as identified by Professor Weber in his evidence in chief is flawed. Hanwha further submits that the same analysis would apply in respect of Hoex 2007 to defeat the arguments raised by REC Solar.

291    In considering this ground I first refer to the evidence in chief of Professors Weber and Cuevas-Fernandez and Dr Winderbaum. I then consider the disclosure of Hoex 2006 before reviewing each of steps (1)-(6) in the light of the parties’ submissions and the evidence. I conclude by analysing the question of lack of inventive step in the light of the relevant law, before turning to the question of whether REC Solar has established that the claims lack an inventive step in light of Hoex 2007.

9.2    The evidence in chief concerning inventive step

9.2.1    Professor Weber

292    In his first affidavit, Professor Weber responds to a series of questions asked of him. He commences by providing his background and experience, aspects of which I have summarised in section 3.2 above. Professor Weber was then asked to describe his general approach to conducting research as at 14 November 2007, which he does by reference to his research practices, including the publications he routinely read and conferences he attended. He was then asked to explain, as at November 2007, his understanding of;

(a)    the operation, function and properties of silicon solar cells;

(b)    passivating layers in silicon solar cells;

(c)    the structure of silicon solar cells and modules; and

(d)    the solar cell manufacturing process,

the result of which, subject to some areas of disagreement with Professor Cuevas-Fernandez, formed the basis for the agreed common general knowledge.

293    Professor Weber was then supplied with a copy of Hoex 2007 and asked to express his opinion as to what that document would have disclosed to him as at November 2007. He gives evidence that he had read Hoex 2007 after the priority date but before being given it for the purpose of the proceedings and that it was likely that he first read it after the priority date following a conference held in San Diego, United States, in May 2008 where he met the primary author, Bram Hoex. Dr Hoex is also the inventor named in the patent. Professor Weber knew other co-authors of the Hoex 2007 paper before November 2007 and had followed the work of each of Dr Altermatt and Dr Schmidt, but was not aware of the work being conducted on aluminium oxide and ALD by Dr Hoex until the San Diego conference.

294    Professor Weber gives evidence of his understanding of the disclosure of Hoex 2007 as if he had read it in November 2007. Following that evidence Professor Weber was asked the Hoex 2007 question:

Having regard only to what was known by you as at November 2007 and the information disclosed in Hoex 2007, and putting out of your mind any additional information which you subsequently learnt, what (if anything) would you have been directly led to try if you were seeking to develop a commercial solar cell that was a useful alternative to, or better than, existing commercial solar cells available at that date? Please assume that you had unimpeded access to any necessary equipment, materials and facilities that you were aware of at that date.

295    In response, Professor Weber describes two structures that in his opinion he would have been directly led to try:

Structure 1: a solar cell based on an n-type silicon wafer with a boron diffusion (to create a p-type emitter) at the sun-facing side of the wafer. For this solar cell structure, the results of Hoex 2007 are directly applicable because they relate to the passivation of a p-type emitter. However, when using an n-type silicon wafer, I could not simply employ the same rear aluminium back surface field structure used in Conventional Solar Cells [as defined in the agreed common general knowledge], which are based on p-type silicon wafer, as I discuss further below.

Structure 2: a PERL solar cell based on a p-type silicon wafer with a phosphorus diffusion (to create an n-type emitter) at the sun-facing side of the wafer. While Hoex 2007 provides results of aluminium oxide passivation of p-type emitters in n-type silicon bulk, I would have considered it very likely that ALD-deposited aluminium oxide films as used by the authors of Hoex 2007 would also provide a high level of surface passivation for undiffused p-type surfaces. This is because Hoex 2007 states that the aluminium oxide films contain a high density of negative charges and demonstrate excellent passivation of diffused p-type surfaces. In my opinion … these two factors in combination make it likely that a high level of passivation could also be achieved on a more lightly doped p-type surface. In a PERL structure, the aluminium oxide would be deposited on the rear of the silicon wafer to passivate the undiffused p-type rear surface.

296    Professor Weber explains that he would have considered it straightforward to implement both structures in a research laboratory and expected that he could produce commercial solar cells based on both, but he would have considered that structure 2 provided an easier transition from existing commercial technology at the time and made more sense commercially to pursue in a reasonable timeframe. He then explains his reasoning in relation to each of these structures in more detail.

297    Professor Weber was then given a copy of Hoex 2006, which he recalls he read at the same time as Hoex 2007, shortly after the San Diego conference in 2008 (that is, after the priority date). He then sets out his understanding of what Hoex 2006 would have disclosed to him had he read it in November 2007. He was then asked a question in the same terms as the Hoex 2007 question in relation to Hoex 2006 (Hoex 2006 question). He gives evidence that he would have been directly led to try the same two structures identified earlier, namely structure 1 and structure 2.

298    In his first affidavit, Professor Weber then proceeds to address other subjects before being asked to review the patent. He gives evidence that it was only after providing his responses to the questions that I have set out above that he was provided with a copy of the patent and asked to review its disclosure.

9.2.2    Professor Cuevas-Fernandez

299    I have summarised parts of the background and experience of Professor Cuevas-Fernandez in section 3.1 above. In his affidavit he provides his response to the background common general knowledge supplied by Professor Weber, largely agreeing with its contents, although he notes that, where that document discusses techniques for surface passivation, it should be emphasised that it was one of several active areas of research in relation to solar cells. After providing more detailed commentary on points of difference with the common general knowledge document, Professor Cuevas-Fernandez was supplied with Hoex 2006 and Hoex 2007 and asked to review the content of each.

300    Professor Cuevas-Fernandez says that he knew Dr Hoex personally and has been a peer reviewer for a number of papers authored by Dr Hoex, including Hoex 2007, which he reviewed in draft before it was published. He did not review Hoex 2006.

301    Professor Cuevas-Fernandez was then provided with a copy of the patent and supplied a review of its contents before returning, later in his affidavit, to providing responses to the evidence of Professor Weber in relation to Hoex 2007, Hoex 2006 and structures 1 and 2.

302    Professor Cuevas-Fernandez considers that the process by which Professor Weber explains that he would have been directly led to structure 1 or structure 2 is contrived, saying that structure 2 in particular, is used extensively in industrially produced solar cells today and is very well known. He considers that without the benefit of hindsight, the person skilled in the art in November 2007 would not have been directly led to try either of these structures. One general reason he gives for this is because of Professor Cuevas-Fernandez’s view that a person skilled in the art would not contemplate such radical changes as Professor Weber contemplates, at least until it had been proven in a research environment and, even then, this might take years and possibly not occur at all. The person skilled in the art is in his view a person working in industry who would not attend to such matters. After stating that position, Professor Cuevas-Fernandez then addressed each of structures 1 and 2 from the perspective of a person in the field working in research and raised further difficulties with the approach adopted by Professor Weber.

9.2.3    Dr Winderbaum

303    I have summarised aspects of Dr Winderbaum’s qualifications in section 3.1 above. Dr Winderbaum gives evidence of the impact of the introduction of PECVD technology to deposit silicon nitride which, in his experience, was a major shift for the photovoltaic industry that was in the process of being adopted by commercial manufacturers around the world. The use of silicon nitride was, in his view, an enabling technology in that it resulted in many other changes being made to the manufacturing processes for solar cells. This and the texturing of multi-crystalline silicon were the two major developments that he had observed before November 2007.

304    Dr Winderbaum gives evidence of his understanding of the disclosure of each of Hoex 2006 and Hoex 2007 in the context of his knowledge before November 2007. He had not read either publication before that date.

9.3    The inventive step joint expert report

305    Professors Weber and Cuevas-Fernandez and Dr Winderbaum conferred and discussed their respective views as at November 2007 on: (a) the commonly known problems concerning solar cells and their manufacture; (b) motivations underpinning the development of commercial solar cells; (c) the audience for and disclosures of Hoex 2006 and 2007. Professor Weber and Cuevas-Fernandez separately discussed their respective views on the answer to the Hoex 2006 and 2007 questions. The fruit of these discussions, and the significant agreement reached by them, was recorded in the IS JER and, to the extent that they differed, was further discussed in concurrently given oral evidence.

9.4    The disclosure of Hoex 2006

306    Hoex 2006 was published in Applied Physics Letters and was received by the editors on 19 April 2006 and published online on 27 July 2006. In the IS JER, Dr Winderbaum and Professors Weber and Cuevas-Fernandez agreed that the audience for the paper was scientists and researchers.

307    Set out below is a summary of the relevant disclosure of Hoex 2006 taken from its text and from my consideration of the oral and written expert evidence.

308    The article is entitled “Ultralow surface recombination of c-Si [crystalline silicon] substrates passivated by plasma-assisted atomic layer deposited Al2O3 [aluminium oxide]”.

309    The abstract provides:

Excellent surface passivation of c-Si has been achieved by Al2O3 films prepared by plasma-assisted atomic layer deposition, yielding effective surface recombination velocities of 2 and 13 cm/s on low resistivity n- and c-Si, respectively. These results obtained for ~30 mm thick Al2O3 films are comparable to state-of-the-art results when employing thermal oxide as used in record-efficiency c-Si solar cells. A 7 nm thin Al2O3 film still yields an effective surface recombination velocity of 5 cm/s on n-type silicon.

310    The opening sentences of the article say:

Surface passivation of crystalline silicon (c-Si) is of key importance for the performance of high efficiency industrial solar cells. The surface to volume ratio is increasing due to the cost-driven reduction of the solar cell thickness, which makes surface passivation a decisive factor for the final solar cell efficiency.

311    By way of background, before November 2007 the skilled reader would understand this passage in the context of the fact that at the time, solar cells were becoming thinner and, as this occurred, the volume of silicon reduced, resulting in the carriers (electrons and holes) being more likely to reach the wafer’s surfaces. The reference to the surface to volume ratio increasing and its consequences is to be understood to mean that the quality of the bulk wafer was becoming relatively less important compared to the silicon surfaces in terms of the overall recombination rate. This was known to be particularly significant in the case of multi-crystalline silicon wafers in the years prior to 2007.

312    The article refers in the next passages to different passivation technologies that had been explored up to the date of the paper, namely the use of amorphous silicon nitride, thermally grown silicon oxide, amorphous silicon carbide and amorphous silicon.

313    In relation to amorphous silicon nitride (or a-SiNx:H) it says:

Hydrogenated amorphous silicon nitride (a-SiNx:H) is routinely applied in solar cell production as an antireflection coating on the front side and provides good surface passivation of low resistivity n-and p-type c-Si. However, the surface passivation of a-SiNx:H on highly doped p-type silicon (e.g., p-type emitters) is rather poor. When a-SiNx:H is applied on the back of a p-type solar cell the high positive built-in charge induces a parasitic junction, limiting the solar cell efficiency.

(Emphasis added.)

314    It was well known before the priority date that amorphous silicon nitride was routinely applied as an antireflection coating in solar cells. It was also known that amorphous silicon nitride provided good surface passivation of both n- and p-type wafers, and that it did not provide good passivation of heavily doped, diffused p-type surfaces and is more suited to heavily doped, diffused n-type surfaces.

315    The passage above explains to the skilled reader that silicon nitride can provide good surface passivation on the front of a structure which features a p-type silicon wafer with an n-type emitter in the near-surface region. The statement “When a-SiNx:H is applied on the back of a p-type solar cell the high positive built-in charge induces a parasitic junction, limiting the solar cell efficiency” explains to the skilled reader that, when applied to a p-type wafer, silicon nitride does provide surface passivation, but has the disadvantage of inducing a parasitic junction. As Dr Winderbaum explained, the main mechanism by which silicon nitride passivates is through a field effect, attributable to its intrinsic positive charge. This positive charge produces undesirable results if it is used to passivate a p-type surface, such as is present at the back of a p-type cell. In November 2007 most commercially produced wafters were made using p-type silicon wafers. However, he was aware that research was being undertaken in academic institutions for the use of n-type wafers as a means of improving efficiency.

316    Consistently with this, Professor Weber explains that he understood at the time that in principle amorphous silicon nitride could be used to passivate the rear surface of a PERC (including a Passivated Emitter and Rear Locally doped (PERL)) structure that consists of an n-type wafer. He explains:

As at November 2007, I knew that the rear of a p-type silicon wafer in a PERC (and PERL) structure was undiffused and hence was more lightly doped than the diffused region in the emitter at the front of the structure. In this case, the impact of positive charge in the silicon nitride deposited on the rear surface of the wafer overwhelms the impact of the p-doping at the rear surface region of the p-type silicon wafer. In other words, the positive charge of the silicon nitride at the rear surface will repel the majority carriers (holes) of the p-type silicon and will attract a far greater density of the minority carriers (electrons) to the surface such that the electrons then become the majority carriers and holes the minority carriers. … This, in effect, “inverts” the near surface region (such that it effectively becomes an n-type surface). …

317    The skilled addressee understood such an inversion to have negative connotations in terms of the efficiency of any passivation, in that it may create a “depletion region” in the silicon close to the surface which can be a source of high recombination and it may create a parasitic shunting path that can reduce the efficiency of a solar cell.

318    Hoex 2006 notes that thermally grown oxide was then the state-of-the-art surface passivation layer for n- and p-type crystalline silicon of arbitrary doping level “and is used in the record-efficiency passivated emitter and real localy–diffused [sic] (PERL) c-Si solar cell”. It goes on:

The surface passivation of the as-grown thermal oxide is moderate, but is significantly improved by subsequent annealing in a forming gas (H2 in N2).

319    After describing an “alneal” scheme, where a sacrificial layer of aluminium oxide is evaporated on the film prior to annealing, the article observes that the high processing temperatures (of about 950-1100 °C) and elaborate processing necessary for the alneal scheme is not always desirable.

320    The article then points to disadvantages of the use of amorphous silicon carbide and hydrogenated amorphous silicon which, although they have recently been demonstrated to have a good level of surface passivation, have significant absorption in the visible part of the solar spectrum and are also thermally unstable.

321    Hoex 2006 then turns to the advantageous features of a different passivation approach involving the use of an aluminium oxide layer, saying:

Another interesting option is the use of the high band-gap dielectric layer Al2O3 as a surface passivation layer. …

In this letter we will show that ultrathin films of Al2O3 exhibit a similar level of surface passivation as alnealed thermal silicon oxide on both n-type and p-type silicon. These films were prepared by plasma-assisted atomic layer deposition (PA-ALD) allowing monolayer growth control of high quality thin films, while the plasma step enables the use of relatively short purging times and low deposition temperatures.

322    The paper then describes an experiment that was conducted by the authors in which Al2O3 films with a thickness of 7-30 nm were grown in a homebuilt plasma ALD reactor. At the time, atomic layer deposition was not used as a process for making solar cells. The films were deposited in cycles that took about 30 seconds per cycle, each cycle increasing the thickness of the film by 1.2 Å. The paper reports that the hydrogen content in the aluminium oxide films used in the study was about 3 at. %.

323    The authors of Hoex 2006 calculate an effective lifetime of the level of surface passivation, and plot this in Fig 1 in the context of excess carrier density for low resistivity p-type silicon substrate. The article shows that the maximum effective lifetime for the samples used is about 1 millisecond (or μs) which the skilled addressee would consider to be a relatively good effective lifetime, showing that the aluminium oxide can provide a very high level of passivation.

324    In the first full paragraph on page 2 of the article, the authors of Hoex 2006 report the effective lifetimes of the 15 and 30 nm aluminium oxide films after annealing and state that, before annealing, the effective lifetimes were “only in the range of 2 – 8 μs”. The skilled reader would understand this to be several hundred times worse than the effective lifetimes after annealing and this would lead that reader to the conclusion that it is necessary to conduct thermal activation of the aluminium oxide in order achieve the full passivation effect provided by the material.

325    A similar calculation is made in the context of n-type silicon substrate in relation to Fig 2 but with poorer results.

326    The article reports at page 2, second column, first full paragraph:

The effective lifetimes measured for a p-type c-Si substrate passivated by a 15 nm Al₂O₃ film in this study are significantly higher compared to the results reported for substrates passivated by a-SiC_x:H films or Al₂O₃ films grown by thermal ALD. The results are comparable to the best results obtained for alnealed thermal SiO₂ and nearly stoichiometric a-SiN_x:H and approach the results obtained for a-Si:H.