Hanwha Q Cells & Advanced Materials Corp. Q-Cells SE (Bitterfeld-Wolfen, OT Thalheim, unknown)

Patent Trials and Appeals Board

Jun 28, 2021

IPR2020-00353 (P.T.A.B. Jun. 28, 2021)

Trials@uspto.gov Paper 25
571-272-7822 Entered: June 28, 2021

UNITED STATES PATENT AND TRADEMARK OFFICE

BEFORE THE PATENT TRIAL AND APPEAL BOARD

LONGI GREEN ENERGY TECHNOLOGY CO., LTD., LONGI SOLAR
TECHNOLOGY CO., LTD.,
LONGI (H.K.) TRADING LTD.,
LONGI (KUCHING) SDN. BHD.,
LONGI SOLAR TECHNOLOGY (TAIZHOU) CO., LTD.,
LONGI SOLAR TECHNOLOGY (ZHEJIANG) CO., LTD.,
LONGI SOLAR TECHNOLOGY (HEFEI) CO., LTD., and LONGI
SOLAR TECHNOLOGY (US), INC.,
Petitioner,
v.
HANWHA Q CELLS & ADVANCED MATERIALS CORP.,
Patent Owner.

IPR2020-00353
Patent 8,933,525 B2

Before CHRISTOPHER L. CRUMBLEY, JEFFREY W. ABRAHAM, and
JASON M. REPKO, Administrative Patent Judges.
REPKO, Administrative Patent Judge.
JUDGMENT
Final Written Decision
Determining All Challenged Claims Unpatentable
35 U.S.C. § 318(a)

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I. INTRODUCTION
LONGi Green Energy Technology Co., Ltd., LONGi Solar
Technology Co., Ltd., LONGi (H.K.) Trading Ltd., LONGi (Kuching) Sdn.
Bhd., LONGi Solar Technology (Taizhou) Co., Ltd., LONGi Solar
Technology (Zhejiang) Co., Ltd., LONGi Solar Technology (Hefei) Co.,
Ltd., and LONGi Solar Technology (Us), Inc. (collectively, “Petitioner”)
filed a petition requesting inter partes review of claims 1–18 of U.S. Patent
No. 8,933,525 B2 (Ex. 1001, “the ’525 patent”). Paper 1 (“Pet.”). Hanwha Q
Cells & Advanced Materials Corp. (“Patent Owner”) filed a Preliminary
Response. Paper 10 (“Prelim. Resp.”).
On June 30, 2020, we instituted an inter partes review of all
challenged claims based on all grounds in the Petition. Paper 11
(“Inst. Dec.”). Patent Owner filed a Response. Paper 15 (“PO Resp.”).
Petitioner filed a Reply. Paper 19 (“Pet. Reply”). Patent Owner filed a Sur-
reply. Paper 20 (“Sur-reply”). An oral hearing was held on March 25, 2021.
A transcript of that hearing has been entered into the record. Paper 24
(“Tr.”).
We have jurisdiction under 35 U.S.C. § 6. This Final Written Decision
is issued under 35 U.S.C. § 318(a). For the reasons that follow, Petitioner
has shown by a preponderance of the evidence that claims 1–18 are
unpatentable.
A. Related Matters
Both parties assert that the ’525 patent is not involved in any pending
litigation. See Paper 9, 2 (Patent Owner’s Updated Mandatory Notices);
Paper 14, 2 (Petitioner’s Updated Mandatory Notices).
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B. The ’525 Patent
The ’525 patent generally relates to semiconductor fabrication for
improved solar-cell efficiency. See Ex. 1001, 1:14–24, 2:40–46. Solar-cell
efficiency is limited by the phenomenon of surface recombination.
Id. at 1:17–20. In solar cells, recombination of charge carriers occurs at the
semiconductor surface. Id. These recombined charge carriers are no longer
available for generating current. Id at 1:20–21. To reduce surface
recombination, semiconductors use passivation layers. Id. at 1:21–24.
Passivation layers can use chemical or field-effect passivation. Id. at 1:25–
52. The ’525 patent uses both types of layers for improved passivation.
Id. at 2:19–27. According to the ’525 patent, forming a layer from two
passivation sublayers with different passivation mechanisms improves
passivation quality “beyond a mere accumulation of the known individual
effects.” Id. at 2:22–27.
C. Claims
Claims 1 and 15, reproduced below, are independent.
1. A semiconductor apparatus comprising:
a semiconductor layer in the form of a wafer and a passivation
layer arranged on a surface of the semiconductor layer and
serving for passivating the semiconductor layer surface,
wherein the passivation layer comprises a chemically
passivating passivation sublayer and a field-effect-
passivating passivation sublayer, which are arranged one
above the other on the semiconductor layer surface;
wherein the chemically passivating passivation sublayer directly
adjoins the field-effect-passivating passivation sublayer
without further intermediate layers being arranged
therebetween and wherein:
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i) the field-effect-passivating passivation sublayer is
substantially formed from a material having a negative
surface charge density; and
ii) a covering layer comprising silicon nitride applied on the
passivation layer.
Ex. 1001, 10:12–29.

15. A method of fabrication for a semiconductor apparatus,
wherein a semiconductor layer in the form of a wafer is provided,
having a semiconductor layer surface, and wherein a chemically
passivating passivation sublayer and a field-effect-passivating
passivation sublayer are applied successively on the
semiconductor layer surface in order jointly to form a passivation
layer, wherein the chemically passivating passivation sublayer
and the field-effect-passivating passivation sublayer are applied
such that chemically passivating passivation sublayer directly
adjoins the field-effect-passivating passivation sublayer without
further intermediate layers being arranged therebetween and
wherein:
i) the field-effect-passivating passivation sublayer is
substantially formed from a material having a negative
surface charge density; and
ii) a covering layer comprising silicon nitride is applied on the
passivation layer.
Id. at 11:1–12:5.

D. Evidence
Name Reference Exhibit No.
Sun US 2009/0165855 A1, published July 2, 2009 1005
Hoex B. Hoex et al., Ultralow surface recombination
of c-Si substrates passivated by plasma-
assisted atomic layer deposited Al2O3, 89
Applied Physics Letters 042112 (2006),
http://dx.doi.org/10.1063/1.2240736
1007
Schmidt J. Schmidt et al., Surface Passivation of High- 1008
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efficiency Silicon Solar Cells by Atomic-layer-
deposited Al2O3, 16 Progress In Photovoltaics:
Research and Applications 461–66 (2008)
Hagino US 2004/0112426 A1, published June 17, 2004 1009

Petitioner relies on the Declaration of Dr. Sanjay Banerjee. Ex. 1003
(“Banerjee Decl.”). Patent Owner relies on the declaration of Dr. Michael
Lebby. Ex. 2001 (“Lebby Decl.”).
E. Asserted Grounds
Petitioner asserts that claims 1–18 are unpatentable on the grounds in
the table below. Pet. 4.
Claims Challenged Pre-AIA
1
35 U.S.C. § Reference(s)
1–6, 8–11, 13–16, 18 103(a) Sun
3, 6, 7, 12, 18 103(a) Sun, Schmidt
5, 7, 12, 14 103(a) Sun, Hoex
6, 17, 18 103(a) Sun, Hagino
II. ANALYSIS
A. Level of Ordinary Skill in the Art
The Supreme Court in Graham v. John Deere Co., 383 U.S. 1 (1966)
set forth four factual inquiries for determining whether a claim is
unpatentable as obvious under 35 U.S.C. § 103(a). KSR International Co. v.
Teleflex Inc. reaffirmed and summarized those four factors: (1) determining
the scope and content of the prior art, (2) ascertaining the differences
between the prior art and the claims at issue, (3) resolving the level of
ordinary skill in the pertinent art, and (4) when in evidence, considering

1 Congress amended § 103 when it passed the Leahy-Smith America Invents
Act (AIA). Pub. L. No. 112–29, § 3(c), 125 Stat. 284, 287 (2011). Here, the
previous version of § 103 applies.

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objective evidence indicating obviousness or nonobviousness. 550 U.S. 398,
406 (2007) (citing Graham, 383 U.S. at 17–18). We review the grounds of
unpatentability in view of the understanding of a person of ordinary skill in
the art at the time of the invention. Graham, 383 U.S. at 17.
According to Petitioner,
A person of ordinary skill in the art in the field of the 525
Patent (semiconductor, e.g., solar cell, design or manufacture) in
the 2009 time frame would have been someone with an advanced
degree involving the discipline of electrical engineering, applied
physics, chemistry, or materials science, and at least two years of
experience designing, developing, or researching in the field.
Pet. 4
Alternatively, Petitioner asserts that a person of ordinary skill in the
art “would have had a bachelor’s degree in electrical engineering, applied
physics, chemistry, or materials science, and at least three years designing,
developing, or researching in the field.” Id. at 5.
In the Institution Decision, we applied Petitioner’s proposed
definition, and we asked the parties to discuss the level of ordinary skill in
the art in the remaining briefing should Patent Owner propose a different
definition. Inst. Dec. 5–6. Patent Owner does not dispute Petitioner’s
proposed level of ordinary skill in the art. (PO Resp. 3), and neither party
disagreed with the level that we applied in the Institution Decision. We
continue to find that the level of ordinary skill identified by Petitioner
(Pet. 4) is consistent with the record. See Inst. Dec. 6. Thus, we use the same
definition here that we used in the Institution Decision.
B. Claim Construction
In inter partes review proceedings, we interpret claims in the same
way as a civil action under 35 U.S.C. § 282(b), “including construing the
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claim in accordance with the ordinary and customary meaning of such claim
as understood by one of ordinary skill in the art and the prosecution history
pertaining to the patent.” 37 C.F.R. § 42.100(b) (2019). Only terms that are
in controversy need to be construed and only to the extent necessary to
resolve the controversy. Nidec Motor Corp. v. Zhongshan Broad Ocean
Motor Co., 868 F.3d 1013, 1017 (Fed. Cir. 2017) (citing Vivid Techs., Inc. v.
Am. Sci. & Eng’g, Inc., 200 F.3d 795, 803 (Fed. Cir. 1999)).
Claim 6 recites that “the passivation layer is embodied as a reflection
layer or as an antireflection layer.” Ex. 1001, 10:46–48 (emphasis added).
Claim 18 recites “wherein the chemically passivating passivation sublayer
and the field-effect-passivating passivation sublayer are applied in such a
way that the passivation layer resulting therefrom acts as a reflection layer or
as an antireflection layer.” Id. at 12:18–21. The parties disagree on what it
means for a layer to be embodied as or act as a reflection layer or an
antireflection layer, as recited in claims 6 and 18. Thus, to resolve the
controversy here, we must determine the proper construction of “reflection
layer” and “antireflection layer” in claims 6 and 18. Id. at 10:46–48.

1. The Parties’ Constructions
The Petition states that the claim terms should be given their plain and
ordinary meaning. Pet. 9–10. But, in analyzing claims 6 and 18, Petitioner’s
mapping to the prior art contains an implicit construction for the recited
reflection and antireflection layers: a layer is (1) a reflection layer if it is part
of a stack of layers that collectively function to enhance reflection on the
back of a solar cell relative to the incident light or (2) an antireflection layer
if it is part of a stack of layers that collectively suppress reflection on the
front of the solar cell relative to the incident light. Id. at 37–40; 53–54
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(discussing improving light-trapping properties); 66–67 (discussing
“suppressing reflection”).
In particular, the Petition refers to multiple layers when discussing
whether passivation layers act as a reflective or antireflective layer. Id. That
is, Petitioner considers the function of multiple layers acting together. See id.
For example, Petitioner states that “it was typical to design the back
passivation layers to act as a reflector.” Id. at 38 (emphasis added).
Likewise, the Petition states that “passivation layers deposited on the front
side of the solar cell would have to act as an anti-reflection layer.” Id.
(emphasis added); see also id at 39 (“all the dielectric layers (i.e., 104a,
106a, 108a, altogether) on top of Sun’s ‘photoelectric conversion layer’ 102
should, altogether, have anti-reflection properties”); see also Tr. 20:4–5
(“All three layers are part of the antireflection stack and each one is
considered to be an antireflection layer.”); id. at 21:1–13 (discussing
collective function). These statements also refer to the layers’ placement,
i.e., on the cell’s front surface or back surface relative to the incident light,
and how the prior art’s stack of layers enhances or suppresses reflection. See
Pet. 37–40; 53–54; 66–67.
Unlike Petitioner, Patent Owner argues that one has to look at each
layer individually to determine whether it is a reflective or antireflective
layer. Tr. 41:20–42:3 (“So we have to look at each piece . . . You can break
it out, and you have to do that. That’s what the claims tell us.”). Patent
Owner argues that an individual layer must be “specifically fashioned” to be
a reflection or antireflection layer. Sur-reply 3.
Also, in Patent Owner’s view, a reflection or antireflection layer is not
merely any dielectric layer. Id. For example, Patent Owner argues that “Dr.
Lebby explained that a [person of ordinary skill in the art] would understand
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an individual antireflection layer is calibrated to minimize the amount of
light reflecting off of the front surface of a solar cell through destructive
interference.” Id. (emphasis added); see also id. at 6 n.1 (discussing how the
antireflection layers must be “specifically calibrated”); Tr. 29:19–21
(discussing “destructive interference”). Patent Owner similarly argues that
“[a] reflection layer is a thick layer placed against the back metal contact of
a solar cell and is used as a cavity to trap light that would otherwise scatter
off of the back metal contact away from the solar cell.” Sur-reply 3 (citing
Ex. 1025, 41:7–42:5; Ex. 2001). Patent Owner thus argues “the optical
properties and thicknesses of a layer must be ‘chosen’ to enable the
functions of reflection or antireflection.” Id. (emphasis in original).
2. Analysis
Having reviewed and considered the record, we agree with Petitioner
that the proper construction of “reflective” and “antireflective” considers
both the layer’s position relative to the incident light and the collective
function of multiple layers. See Pet. 37–40; 53–54; 66–67. That is, a layer is
(1) a reflection layer if it is part of a stack of layers that collectively function
to enhance reflection on the back of a solar cell relative to the incident light
or (2) an antireflection layer if it is part of a stack of layers that collectively
suppresses reflection on the front of the solar cell relative to the incident
light. Id. Our reasoning follows.
Under Phillips, we first look to the claim language. Phillips, 415 F.3d
1303, 1312 (Fed. Cir. 2005). The claim recites that the layer must be
“embodied as” (claim 6, Ex. 1001, 10:46–48) or “act as” (claim 18, id. at
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12:18–21) a reflection or antireflection layer.2 The parties, though, do not
argue that the issues here turn on the meaning of “embodied” or “act.” See,
e.g., PO Resp. 18; Sur-reply 11–26; Tr. 11:9–20. And we determine that the
difference in claim language does not affect our analysis of the prior art. So
we do not need to construe the terms “embodied” or “act.” Apart from those
terms, the claims to not impose any other limitations on the recited reflection
layer or antireflection layer. For example, the claims do not include any
requirements on what degree of reflection or antireflection is necessary to
satisfy the limitation.
Likewise, the written description of the ’525 patent does not define
reflection or antireflection by a particular performance threshold or other
metric. As stated in Phillips, “the specification is always highly relevant to
the claim construction analysis. Usually, it is dispositive; it is the single best
guide to the meaning of a disputed term.” Phillips, 415 F.3d at 1315
(internal quotes and citation omitted). Here, the ’525 patent explains that
thickness, among other “optical properties,” determines whether a layer
embodies an antireflection or reflection layer. Ex. 1001, 5:34–38; see also
id. at 7:1–10 (discussing “additional optical properties”). Yet the ’525 patent
does not further specify how to make a layer reflective or anti-reflective. See
generally id. For instance, the patent does not specify an optimal thickness.
See id.

2 We agree with Petitioner that the term “or” indicates that a passivation
layer that is embodied as, or acts as, either an antireflection layer or a
reflection layer satisfies claims 6 and 18. Pet. Reply 2 (citing Ex. 1025,
120:12–122:7). Patent Owner does not dispute this. See generally PO Resp.;
Sur-reply (arguing both reflection and antireflection layer limitations in the
alternative).
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Instead of focusing on a performance metric or a property like
thickness, Petitioner’s interpretation emphasizes the layer’s actual—as
opposed to intended—role in the overall design of the solar cell, e.g., as
“part of a reflection layer.” See, e.g., Pet. 37–38. In this way, Petitioner’s
assertions are consistent with the language of claims 6 and 18, which recite
the passivation layer is embodied as “a reflection layer or as an
antireflection layer.” Ex. 1001, 10:47–48 (claim 6), 12:20–21 (claim 18)
(emphasis added). We emphasize “a” and “an” because those terms indicate
that more than one layer can be a reflection or antireflection layer:
“As a general rule, the words ‘a’ or ‘an’ in a patent claim carry
the meaning of ‘one or more.’” TiVo, Inc. v. EchoStar Commc’ns
Corp., 516 F.3d 1290, 1303 (Fed. Cir. 2008). “The exceptions to
this rule are extremely limited: a patentee must evince a clear
intent to limit ‘a’ or ‘an’ to ‘one.’” Baldwin Graphic Sys., Inc. v.
Siebert, Inc., 512 F.3d 1338, 1342 (Fed. Cir. 2008) (internal
quotation marks and citation omitted). “The subsequent use of
definite articles ‘the’ or ‘said’ in a claim to refer back to the same
claim term does not change the general plural rule, but simply
reinvokes that non-singular meaning.” Id. An exception to the
general rule arises only “where the language of the claims
themselves, the specification, or the prosecution history
necessitate a departure from the rule.” Id. at 1342–43.
01 Communique Lab., Inc. v. LogMeIn, Inc, 687 F.3d 1292, 1297
(Fed. Cir. 2012). Here, we see no exception that would necessitate a
departure from the general rule. See, e.g., Ex. 1001, 1:1–10:10, (the
descriptive part of the specification); Ex. 1002 (file history of the patent).
Petitioner’s assertions (Pet. 38–39) also imply a construction that is
consistent with the ’525 patent’s descriptions of the layers in a solar cell.
The patent describes how another layer can work with a passivation layer to
influence its optical properties:
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In one advantageous development it is provided that an
intermediate layer is arranged between the chemically
passivating passivation sublayer and the field-effect-passivating
passivation sublayer. The intermediate layer can serve for
influencing or optimizing electrical, optical and/or mechanical
properties of the passivation layer or the connection between the
two passivation sublayers
Ex. 1001, 4:35–47 (emphasis added). In this case, a stack comprises the
intermediate layer and the passivation layer. See id. The patent explains that
the layers can have a cumulative effect on the stack’s overall properties.
Id. at 4:48–52, cited in Pet. Reply 16 n.5. The patent also explains that
adding another layer to the passivation layer adapts it for antireflection. Id.
After describing this embodiment, the phrase “antireflection layer–ARC”
appears in parentheses. Id.; see also Sur-reply 21 (discussing “antireflection
coating ‘ARC’”). Thus, in this example, the patent treats the passivation
layer as part of an antireflection layer because it contributes to the
antireflective properties of the entire structure, including the ARC. See
Ex. 1001, 4:48–52.
Petitioner’s interpretation (Pet. 38–39) is also consistent with the plain
and ordinary meaning of reflection and antireflection layers as understood
by a person of ordinary skill in the art, as demonstrated by Patent Owner’s
own evidence and arguments. For example, Dr. Lebby describes how a solar
cell’s layers work together: When dielectric reflection layers are placed
between an aluminum metal sheet and the substrate, the dielectric reflection
layer acts as a cavity that traps light. Lebby Decl. ¶ 45, discussed in PO
Resp. 11–12. Dr. Lebby also refers to the collection of layers as dielectric
“reflection layers,” which indicates that the layers can work together to
improve overall reflection. Id.
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Petitioner’s position is also consistent with Patent Owner’s
characterization of Kavakli (Ex. 1030). Sur-Reply 10–11. Patent Owner
notes that Kavakli teaches that “the number of layers and their relative
position in the stack also impacts” antireflection. Id. at 11 (citing Ex. 1030,
351–352). We agree that the cited teachings support this statement: Kavakli
selects the inside layer’s properties based on those of the outside layer.
Ex. 1030, 351–352. Thus, like Petitioner’s implicit construction (Pet. 38–
39), Kavakli considers how multiple layers work together.
Also, in arguing against Petitioner’s simulated experiments, Patent
Owner explains that “after light is already trapped in the simulated top-layer
cavity of SiN, the SiO2/Al2O3 layers underneath would also contribute to
the light trapping,” and thus, Patent Owner contends that Petitioner should
account for “any additive impact of SiO2/Al2O3 to reflection when placed
underneath the SiN top layer.” Sur-reply 24 (emphasis in original). In this
way, Patent Owner acknowledges that one must account for the collective
function of the stack of layers. See id.
Patent Owner does offer a rebuttal to Petitioner’s implicit
construction, arguing that Petitioner’s focus on the stack as a whole renders
claims 6 and 18 superfluous. Id. at 4; see also Tr. 41:20–42:3 (arguing that
the layers should be considered individually). But we do not agree that
considering the other layers’ functions results in a boundless construction.
Petitioner’s implicit construction at least excludes layers that are not part of
a stack that enhances or suppresses reflection. That is, under the construction
that is used in Petitioner’s analysis, the claims would exclude a passivation
layer that does not enhance or suppress reflection by itself and is also not
used with another layer to enhance or suppress reflection. See Pet. 37–40;
53–54; 66–67. Also, the terms “reflection” and “antireflection” limit the
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placement of the layer. Specifically, Dr. Banerjee explains how a layer’s
placement relative to the incident light—i.e., on the front or back of the solar
cell—is one indication of whether a layer is a reflective layer or
antireflective layer. Banerjee Decl. ¶¶ 118–119.
Consistent with the ’525 patent’s description, we also disagree with
Patent Owner’s construction to the extent that it uses a performance metric
or threshold to determine whether a layer is a reflection or antireflection
layer. See, e.g., PO Resp. 17–20; Sur-reply 3, 7; Tr. 31:15–32:20. That is,
Patent Owner argues that antireflection layers must have an “optimal
thickness.” PO Resp. 17–20. Patent Owner cites a specific equation known
as “the quarter wavelength equation.” Id. at 17 (citing Lebby Decl. ¶ 57, Ex.
2003, 1:46–60, Ex. 2002, 80–81); see also Sur-reply 7 (discussing the
equation). In Patent Owner’s view, to be an antireflection layer, the layer
must be designed “to minimize the amount of light reflecting off of the front
surface of a solar cell through destructive interference” or otherwise
“specifically fashion[ed]” to have an optimal thickness. Sur-reply 3.
Patent Owner’s claim-construction arguments, though, are
undermined by Dr. Lebby’s and Dr. Banerjee’s testimony on how solar cells
are designed. See PO Resp. 16–20, 24–27; Sur-reply 2–7. Specifically, Dr.
Lebby was asked about a threshold value and answered:
I haven’t seen anything in the prior art that relates to the solar
cells that indicates that there is a threshold for reflective to
antireflective. So I certainly haven’t seen those metrics
discussed, and I am certainly not aware of those metrics.
Ex. 1025, 19:16–25. Dr. Lebby emphasizes throughout his testimony that
no single parameter determines whether a layer is reflective or
antireflective. Id. at 19:16–25, 43:18–19, 138:8–14. Dr. Lebby stated, “That
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is what I have been indicating all day in this deposition[:] It’s not just the
thickness issue.” Id. at 138:8–14.
Likewise, in the cited deposition from an ITC case3 not involving the
’525 patent, Dr. Banerjee was asked about the “ideal lambda” to use in the
quarter-wavelength formula when designing a solar cell. Ex. 2004, 248:13–
249:3. Dr. Banerjee replied,
I mean, unfortunately, the solar spectrum is a broadband
spectrum. So you look at the solar spectrum, and I think that’s
shown in Nakano,4 if I remember right. So you pick something
sort of in the middle. The visible part of the spectrum is between
400 to 800 nanometers. But then you have to couple that with the
band gap of silicon, which is 1.1 EV. So something on the order
of 500 nanometers will be a reasonable choice.
Id., discussed in Sur-reply 7–8. Also, Dr. Banerjee was asked about whether
30 nm of aluminum oxide will have good antireflective properties at a
particular wavelength. Id. at 250:13–19. Dr. Banerjee replied that anti-
reflection is not defined by a particular wavelength:
Well, the choice of 500 nanometers was somewhat arbitrary. So
it would be -- you know, it’s not as if it’s anti-reflective at
precisely one wavelength. It’s a range, you know. At that specific
wavelength it will be more or less perfect cancellation. But
around that wavelength also there would be partial cancellation.
Id., cited in Sur-reply 8.
We do not view Dr. Banerjee’s testimony in the ITC deposition as
contradicting Petitioner’s position or the Banerjee Declaration in this case.
Sur-reply 5–8. Rather, like Dr. Lebby’s testimony, Dr. Banerjee’s

3 Patent Owner filed the transcript of Dr. Banerjee’s testimony, conducted on
September 4, 2019, from a matter before the United States International
Trade Commission (ITC): Certain Photovoltaic Cells and Products
Containing Same, Inv. No. 337-TA-1151. Ex. 2004.
4 U.S. Patent No. 4,463,216 to Nakano et al. is Exhibit 2003.
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description of “something sort of in the middle” (id. at 248:18–19) and
“around that wavelength” (id. at 250:18) supports the proposition that one
specific parameter does not define whether an individual layer is reflective
or antireflective.
Indeed, because Petitioner does not rely on performance metrics or
optimization of individual layers in the Petition, Petitioner’s assertions align
with Dr. Lebby’s and Dr. Banerjee’s testimony discussed above. See Pet.
38–39. The grounds in the Petition address how a layer functions within a
collection or stack of layers placed in a specific location, not the degree of
enhancement or suppression of reflection that an individual layer provides.
Likewise, we disagree with Patent Owner’s argument that we should
consider the designer’s intended purpose for the layer. See PO Resp. 17–30;
Sur-reply 3, 7. First, such a construction would turn on one’s subjective
intent, which is not a proper basis for construing claim terms. See, e.g.,
Geneva Pharms., Inc. v. Glaxo-SmithKline PLC, 349 F.3d 1373, 1384 (Fed.
Cir. 2003).
Second, the record shows that, to determine a designer’s intended
purpose for a layer, one would have to account for numerous possible
parameters and functions. See, e.g., Ex. 1025, 19:16–25 (Dr. Lebby’s
testimony about thresholds); Ex. 2004, 250:13–19; Ex. 2004, 248:13–259:3
(Dr. Banerjee’s testimony about “ideal” parameters). Dr. Lebby testified that
“it is not just the thickness” that determines antireflection, but “the
composition, the refractive index, what its performance is over wavelengths .
. . come into play, too.” Ex. 1025, 147:7–11; see also id. at 138:8–14. Even
Patent Owner acknowledges that “a POSITA would not conclude that a
passivation layer is an antireflection layer merely based on its thickness.”
Sur-reply 16–17 (citing Ex. 2001 ¶¶ 60–64).
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One may design a layer to perform well for multiple purposes. For
example, the ’525 patent explains that passivation layers may perform
functional tasks during solar-cell fabrication, serving as etching, texture, or
diffusion barriers. Ex. 1001, 6:56–59. Yet the record provides little guidance
on how to use a particular equation or metric, for example, to determine the
designer’s intent. Thus, in construing the claims, we do not consider what
the designer may have intended when choosing a specific layer. See Sur-
reply 3, 7, 14.
In sum, we disagree with Patent Owner’s argument that the claims
require an intentional choice to embody the passivation layer as a reflection
or antireflection layer. Sur-reply 3; see also Tr. 31:15–32:20 (arguing for
particular values used to classify layers). Nor do we consider the claims to
require evaluating the reflective or antireflective properties of the layers in
isolation. Sur-reply 4; Tr. 41:20–42:3.
For claims 6 and 18, we adopt the construction applied in Petitioner’s
analysis in the Petition: A layer is (1) a reflection layer if it is part of a stack
of layers that collectively function to enhance reflection on the back of a
solar cell relative to the incident light or (2) an antireflection layer if it is part
of a stack of layers that collectively suppress reflection on the front of the
solar cell relative to the incident light. Pet. 37–40; 53–54; 66–67. Because
nothing more specific is needed to resolve the issue in this Decision, we do
not further construe “reflection layer” or “antireflection layer.”
C. Uncontested Grounds: Claims 1–5 and 7–17
In our Institution Decision, we concluded that Petitioner’s argument
and evidence demonstrated a reasonable likelihood that claims 1–18 were
unpatentable as obvious based on the challenges identified in the table in
section I.E. Inst. Dec. 2. We must now determine whether Petitioner has
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established by a preponderance of the evidence that the specified claims are
unpatentable over the cited prior art. 35 U.S.C. § 316(e); 37 C.F.R.
§ 42.1(d). Petitioner “has the burden from the onset to show with
particularity why the patent it challenges is unpatentable.” Harmonic Inc. v.
Avid Tech., Inc., 815 F.3d 1356, 1363 (Fed. Cir. 2016). This burden never
shifts to Patent Owner. See Dynamic Drinkware, LLC v. Nat’l Graphics,
Inc., 800 F.3d 1375, 1378 (Fed. Cir. 2015).
We previously instructed Patent Owner that “any arguments for
patentability not raised in the [Patent Owner Response] may be deemed
waived.” Paper 12, 8; see also In re Nuvasive, Inc., 842 F.3d 1376, 1381
(Fed. Cir. 2016) (holding that patent owner’s failure to make arguments at
trial as instructed in the scheduling order constitutes waiver). Also, the
Board’s Trial Practice Guide states that the Patent Owner Response “should
identify all the involved claims that are believed to be patentable and state
the basis for that belief.” Patent Trial and Appeal Board Consolidated Trial
Practice Guide 66 (Nov. 20, 2019), available at http://www.uspto.gov/
TrialPracticeGuideConsolidated.
In the Response, Patent Owner only argued for the patentability of
claims 6 and 18, which depend from claims 1 and 15. Before considering the
patentability of claims 6 and 18, we first analyze the Petitioner’s challenges
to claims 1–5 and 7–17.
1. Obviousness over Sun
Petitioner asserts that claims 1–5, 8–11, and 13–16 are unpatentable as
having been obvious over Sun alone. Pet. 17–50.
a) Sun
Sun generally relates to passivation layers for solar cells. Ex. 1005,
Abstract. Sun uses two passivation layers. Id. The first passivation layer is
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disposed on the substrate. Id. The second passivation layer is between the
substrate and first passivation layer, and the material for the second layer is
the oxide of the substrate material. Id. According to Sun, this arrangement
enhances the surface-passivation effect and carrier lifetime, which improves
the solar cell’s photoelectric-conversion efficiency. Id.
b) Claim 1
The Petition contains an analysis of how Sun allegedly teaches or
suggests each limitation of claim 1. Pet. 17–32. Petitioner supports its
assertions with Dr. Banerjee’s testimony. Banerjee Decl. Patent Owner does
not substantively address these assertions or otherwise contend that the art
lacks any of the features recited in claim 1. See PO Resp. 14–29.
The Semiconductor Layer
Claim 1 recites, in part, “a semiconductor layer in the form of a
wafer.” Ex. 1001, 10:13. Petitioner asserts that photoelectric-conversion
layer 102 corresponds to the claimed semiconductor layer. Id. Petitioner’s
assertion is adequately supported by Dr. Banerjee’s undisputed testimony,
which we credit. See Banerjee Decl. ¶ 80. And in the paragraph cited in the
Petition, Sun states that the photoelectric-conversion layer 102 is a p-type
poly-silicon wafer. Ex. 1005 ¶ 39. Thus, we find that Sun teaches a
semiconductor apparatus comprising “a semiconductor layer in the form of a
wafer,” as recited in claim 1. Pet. 18–19.
The Chemically Passivating Sublayer
Claim 1 recites, in part, “a passivation layer arranged on a surface of
the semiconductor layer and serving for passivating the semiconductor layer
surface, wherein the passivation layer comprises a chemically passivating
passivation sublayer.” Ex. 1001, 10:13–16.
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Petitioner asserts that Sun’s second passivation layer performs the
same chemical passivation that is disclosed in the ’525 patent. Pet. 20.
Specifically, Petitioner asserts that the patent’s chemical passivation relies
on chemical saturation of free-surface (dangling) bonds. Id. at 21. For its
silicon semiconductor solar cells, the ’525 patent uses thermal growth of a
silicon-oxide (SiO2) layer. Id. (citing Ex. 1001, 1:31–39, 3:16–20).
Likewise, Petitioner asserts that Sun uses thermal oxidation of the silicon-
oxide layer. Id. at 22 (citing Ex. 1005 ¶ 19; Banerjee Decl. ¶ 86). Relying on
Dr. Banerjee’s testimony, Petitioner asserts that one skilled in the art would
understand that a silicon-oxide layer formed in this way would chemically
passivate the silicon wafer by reducing the density of surface states. Id.
(citing Ex. 1022, H388–390; Banerjee Decl. ¶ 86). Although Petitioner
points out other ways that Sun’s second passivation layer meets the claimed
chemical passivation layer (see id. at 21–25), based on Petitioner’s
assertions discussed here we find that the limitation is met by Sun.
The Field-Effect Passivating Sublayer
In addition to the chemically passivating layer, the recited passivation
layer also comprises “a field-effect-passivating passivation sublayer.”
Ex. 1001, 10:17–18.
As for this field-effect passivating layer, Petitioner asserts that Sun’s
first passivation layer performs the same field-effect passivation that is
disclosed in the ’525 patent. Pet. 25 (citing Ex. 1005 ¶¶ 26, 43, Fig. 2;
Banerjee Decl. ¶ 91). For example, Petitioner points out that the ’525 patent
describes aluminum oxide as an example of a negatively-charged sublayer
for field-effect passivation. Id. at 26 (citing Ex. 1001, 1:40–52;
Banerjee Decl. ¶ 91). Likewise, Sun’s first passivation layer is aluminum
oxide. Ex. 1005 ¶ 26, cited in Pet. 26. Sun explains that this layer enhances
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the surface-passivation effect by pushing away electrons from the surface by
fixed negative charges. Id. For at least this reason, we find that Sun teaches
the recited “field-effect-passivating passivation sublayer is substantially
formed from a material having a negative surface charge density,” as recited
in claim 1.
Thus, Petitioner shows that Sun’s passivation layer comprises (1) a
chemically passivating passivation sublayer and (2) a field-effect passivating
passivation sublayer, as recited in claim 1. Pet. 20–29.
The Arrangement of Passivating Sublayers
Claim 1 further limits the arrangement of the sublayers: “one above
the other,” “on the semiconductor layer surface,” and “the chemically
passivating passivation sublayer directly adjoins the field-effect-passivating
passivation sublayer without further intermediate layers being arranged
therebetween.” Ex. 1001, 10:14–24.
Figure 2 of Sun with Petitioner’s annotations is reproduced below.
Pet. 19.

Sun’s Figure 2, above, shows a cross-sectional view of the solar cell’s
structure with colored layers. Id.
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Petitioner asserts that Sun’s passivation layer is formed by layers 104a or
104b in red and 106a or 106b in blue. Id. According to Petitioner, layers
104a or 104b (red) are chemically passivating sublayers, layers 106a and
106b (blue) are field-effect passivating sublayers, and the photoelectric-
conversion layer 102 (green) is a semiconductor layer. Id. at 19, 20, 30.
Indeed, Sun’s Figure 2 shows passivation layers 106a and 104a (blue, red)
on the semiconductor layer surface 102 (green), and there are no
intermediate layers between those passivation layers. Ex. 1005, Fig. 2.
Thus, we find that Sun’s sublayers are “one above the other,” “on the
semiconductor layer surface,” and “the chemically passivating passivation
sublayer directly adjoins the field-effect-passivating passivation sublayer
without further intermediate layers being arranged therebetween.” Pet. 19,
20, 30.
The Covering Layer
Claim 1 further recites, in part, “a covering layer comprising silicon
nitride applied on the passivation layer.” Ex. 1001, 10:28–29. We find that
Sun’s layer 108a meets this limitation. Pet. 31. In particular, Sun’s silicon-
nitride layer 108a is applied on and covers passivation layer 106a (or 108b
and 106b). Ex. 1005 ¶¶ 23, 28, cited in Pet. 31; see also Banerjee
Decl. ¶ 101
In summary, we find that for the reasons given, Petitioner has shown
by a preponderance of the evidence that Sun teaches each limitation of claim
1 and that the claim is unpatentable. We adopt Petitioner’s analysis, which
Patent Owner does not contest.
c) Claim 15
The Petition contains an analysis of how Sun allegedly teaches or
suggests each limitation of claim 15. Pet. 46–49. Petitioner supports this
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analysis with undisputed testimony of Dr. Banerjee. See Banerjee Decl.
¶¶ 141–147. Patent Owner does not contest these grounds. We have
reviewed Petitioner’s uncontested assertions. For reasons similar to those
discussed in connection with claim 1, we determine that these assertions are
sufficiently supported by the evidence of record. See supra § II.C.1.b).
d) Claims 2–4, 8–11, 13, 14, and 16
For dependent claims 2–4, 8–11, 13, 14, and 16, Petitioner provides a
detailed analysis identifying where Sun teaches or suggests each limitation.
Pet. 32–50. Patent Owner does not contest these grounds. Upon review of
the entirety of the record, we credit the testimony of Dr. Banerjee and adopt
Petitioner’s uncontested analysis. Thus, we determine that Petitioner has
shown by a preponderance of the evidence that the subject matter recited in
claims 2–4, 8–11, 13, 14, and 16 would have been obvious.
e) Claim 5
Claim 5 recites, “The semiconductor apparatus as claimed in claim 1,
wherein the field-effect-passivating passivation sublayer has a thickness in a
range of between 0.1 and 10 nm.” Ex. 1001, 10:43–45.
Petitioner asserts that Sun’s aluminum-oxide layer is a field-effect
passivation layer with a thickness of 15 nm. Pet. 35. Petitioner
acknowledges that 15 nm falls outside the claimed range. Id. at 36.
According to Petitioner, reducing the thickness of Sun’s aluminum-oxide
layer would save time and money. Id. (citing Ex. 1008, 465).
Petitioner cites Hoex to show that one skilled in the art would have
understood that an aluminum-oxide layer with a thickness below 10 nm can
effectively provide field-effect passivation. Pet. 59 (citing Ex. 1007,
Abstract; Banerjee Decl. ¶ 173). Petitioner asserts that both Sun and Hoex
use ALD, and thinner layers would have been less expensive to produce with
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that method. Pet. 61 (citing Ex. 1008, 465; Banerjee Decl. ¶ 175). According
to Petitioner, a thinner passivation would perform equally as well as Sun’s
15 nm layer. Pet. 60. In this way, the device provides the same performance
at a lower cost. See id.
In its Preliminary Response, Patent Owner argued that Sun does not
teach or suggest the subject matter of claim 5. Prelim. Resp. 6–8. In the
Institution Decision, we explained why Petitioner’s evidence and arguments
were persuasive on the preliminary record. Inst. Dec. 11–14. Patent Owner
did not present arguments in connection with claim 5 in its Response. See
PO Resp.
After considering the full record developed during the trial, we
maintain our conclusions from the Institution Decision. Inst. Dec. 11–14.
The evidence of record supports Petitioner’s position that reducing the
number of deposition cycles reduces costs. Pet. 61 (citing Ex. 1008, 465;
Banerjee Decl. ¶ 175). We credit Dr. Banerjee’s undisputed testimony that
reducing the deposition cycles would, in turn, reduce the amount of time and
materials used for the atomic layer deposition (ALD) of aluminum oxide.
Banerjee Decl. ¶ 175. Dr. Banerjee’s testimony and the assertions in the
Petition are consistent with the objective evidence provided, including
Hoex’s discussion of the cost benefits of thin films. See Ex. 1007, 042112-3
(discussing process optimization). Thus, we adopt Petitioner’s analysis,
which Patent Owner has not contested.
From the entirety of the record, including our previous analysis in the
Institution Decision, we determine that Petitioner has shown by a
preponderance of the evidence that the subject matter of claim 5 would have
been obvious.
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2. Obviousness over Sun and Schmidt
Petitioner asserts that subject matter of claims 7 and 12 would have
been obvious over the combined disclosures of Sun and Schmidt. Pet. 54–
58.
a) Schmidt
Schmidt assesses the performance of atomic-layer deposited
aluminum oxide as a rear-surface passivating dielectric layer for solar cells.
Ex. 1008, Abstract. Schmidt discloses the rear-surface recombination
velocity for a stack consisting of a 30 nm aluminum-oxide film covered by a
200 nm plasma-enhanced-chemical-vapor-deposited silicon oxide (SiOx)
layer, among other test results. Id.
b) Claims 7 and 12
Petitioner provides a detailed analysis identifying where Sun and
Schmidt teach or suggest each limitation of claims 7 and 12. Pet. 54–58.
Petitioner also provided articulated reasoning, supported by rational
underpinnings, why one of ordinary skill in the art would have made the
Sun-Schmidt combination. See KSR, 550 U.S. at 418. Based on Petitioner’s
analysis, we find that a person of ordinary skill in the art would have
combined Sun and Schmidt, and this combination would have been within
the level of ordinary skill in the art. Id. Patent Owner does not contest these
grounds. Upon review of the entirety of the record, we credit the undisputed
testimony of Dr. Banerjee and adopt Petitioner’s uncontested analysis. Thus,
we determine that Petitioner has shown by a preponderance of the evidence
that the subject matter recited in claims 7 and 12 would have been obvious.
3. Obviousness over Sun and Hagino
Petitioner asserts that the subject matter of claim 17 would have been
obvious over the combined disclosures of Sun and Hagino. Pet. 68–71.
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a) Hagino
Hagino generally relates to solar-cell manufacturing. Ex. 1009,
Abstract. In Hagino’s solar cell, the light-receiving surface passivation film
entirely covers the light-receiving region. Id. ¶ 32. Hagino explains that the
passivation film acts as an antireflection film. Id.
b) Claim 17
The Petition contains an analysis of how Sun and Hagino allegedly
teach or suggest each limitation of claim 17. Pet. 68–71. Petitioner supports
this analysis with Dr. Banerjee’s testimony. Banerjee Decl. ¶¶ 190–195.
Petitioner also provided articulated reasoning, supported by rational
underpinnings, why one of ordinary skill in the art would have made the
Sun-Hagino combination. See KSR, 550 U.S. at 418. Based on Petitioner’s
analysis, we find that a person of ordinary skill in the art would have
combined Sun and Hagino, and this combination would have been within the
level of ordinary skill in the art. Id. Patent Owner does not contest these
grounds. Upon review of the entirety of the record, we credit the undisputed
testimony of Dr. Banerjee and adopt Petitioner’s uncontested analysis. Thus,
we determine that Petitioner has shown by a preponderance of the evidence
that the subject matter recited in claim 17 would have been obvious.
D. Contested Grounds: Claims 6 and 18
Claim 1 recites a passivation layer comprising (1) a field-effect
passivation sublayer and (2) a chemical passivation sublayer. As discussed
above, Petitioner has shown that Sun teaches both layers. Supra § II.C.1.b).
Claim 6 further recites that the passivation layers be “embodied as a
reflection layer or as an antireflection layer.” Ex. 1001, 10:46–48 (emphasis
added). Claim 18 recites a similar limitation in a method claim: “the
chemically passivating passivation sublayer and the field-effect-passivating
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passivation sublayer are applied in such a way that the passivation layer
resulting therefrom acts as a reflection layer or as an antireflection layer.”
Id. at 12:17–21 (emphasis added). Because it uses the term “or,” claims 6
and 18 require only one of a reflection or antireflection layer. In the sections
that follow, we explain why we determine Petitioner has shown that it would
have been obvious to embody a passivation layer as either a reflection layer
or an antireflection layer.
Petitioner has shown by a preponderance of the evidence that the
subject matter of claims 6 and 18 would have been obvious based on four
alternative theories: Petitioner asserts that Sun’s passivation layers are
embodied as or act as reflection layers, or in the alternative, it would have
been obvious to combine Sun and Schmidt to arrive at the claimed reflection
layers. Pet. 37–38, 53–54. We discuss the recited reflection layer in
section II.D.1. Petitioner also asserts Sun’s passivation layers are embodied
as or act as antireflection layers, or in the alternative, it would have been
obvious to combine Sun and Hagino to arrive at the claimed antireflection
layers. Id. at 38–40, 65–67. We discuss the recited antireflection layer in
section II.D.2. As noted above, Petitioner need only prevail on one of these
four alternative theories; we determine below that it has sufficiently
established all four.
1. The Reflection Layer
As discussed in the claim-construction section above, we agree with
Petitioner that, in claims 6 and 18, a layer can be a reflection layer if it is
part of a stack of layers that collectively enhances reflection on the back side
of a solar cell relative to the incident light. Supra § II.B. Because nothing
more specific is needed to resolve the issue in this Decision, we do not
further construe “reflection layer.”
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a) The Petition: Claim 6, Sun alone
Petitioner asserts that “[o]ne skilled in the art would have expected
(and certainly have found it obvious) that the silicon oxide/aluminum oxide
passivation layers in Sun that are deposited on the back side of the solar cell
(104b and 106b) would act as part of a reflection layer.” Pet. 38 (emphasis
added). As discussed above, Sun discloses the same three layer stack on the
back of the solar cell as claim 1. Supra § II.C.1.b). Petitioner asserts that “it
was typical to design the back passivation layers to act as a reflector.” Id.
(citing Ex. 1008, 461, 464–465; Ex. 1003 ¶ 120). To support this assertion,
Petitioner cites Schmidt. Pet. 37–38.
According to Petitioner, Schmidt teaches that a silicon-
oxide/aluminum-oxide stack acts as a reflection layer on a cell’s rear
surface. Id. at 38. Petitioner asserts that Schmidt teaches that a rear
passivation layer that uses aluminum oxide (Al2O3) should be an effective
reflector of near-bandgap photons. Id. (citing Ex. 1008, 464–465, Table II)
b) Analysis: Claim 6, Sun alone
The Petition shows that Sun’s passivation layers are (1) positioned on
the solar cell’s rear surface relative to the incident light and (2) used together
with the silicon-nitride layer. Pet. 37–38. Patent Owner does not dispute that
Sun’s silicon-nitride layer is a reflection layer, stating that “[a] POSITA
would have readily understood that Sun includes silicon nitride layer 108b
on the back of its solar cell as a reflection layer.” PO Resp. 24 (citing Lebby
Decl. ¶ 75). Thus, Sun’s passivation layer is part of a stack of layers that
collectively enhances reflection on the back surface of a solar cell relative to
the incident light. For this reason, which is discussed in more detail below,
Petitioner has shown that Sun’s silicon oxide/aluminum oxide passivation
layer deposited on the back side of the solar cell, without further
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modification, “is embodied as a reflection layer” as recited in claim 6.
Pet. 38.
Schmidt supports Petitioner’s assertion that the reflective effect of all
the layers on the rear surface of Sun’s cell should be considered together. Id.
(citing Ex. 1008, 461, 464–465; Ex. 1003 ¶ 120). Specifically, Schmidt
explains that it is desirable for a cell’s rear stack to improve light trapping:
“the SiO2/Al stack at the cell rear acts as an excellent reflector for near-
bandgap photons, significantly improving the light trapping properties and
hence the short-circuit current of the cell.” Ex. 1008, 461, quoted in Pet. 38.
This shows that the position of the layer—i.e., whether it is part of the “rear
stack”—is relevant to its function. See id.
Schmidt refers to the performance of an Al2O3/SiOx stack, not just the
performance of individual layers. Id. at 464. For example, Schmidt states
that “[a]ll three rear structures are equally effective reflectors for near-
bandgap photons (Rr = 91%).” Id. (emphasis added), quoted in Pet. 38, 54.
Here, Schmidt’s “rear structures” include an Al2O3/SiOx stack, comprising
30 nm of Al2O3 and 200 nm of SiOx. Id. at 465 (Table II). Like Schmidt,
Petitioner considers Sun’s passivation layer, which is part of the stack that
includes a silicon-nitride layer, to be embodied as a reflection layer. Pet. 38.
Patent Owner argues that Schmidt uses a silicon-oxide/aluminum
metal (SiO2/Al) stack, instead of a silicon-oxide/aluminum-oxide stack, like
Sun. PO Resp. 25 (citing Ex. 1007, 461, Lebby Decl. ¶ 77). We disagree.
Although Schmidt discusses SiO2/Al stacks in the introduction, Schmidt
largely examines the efficiency of using thin films of aluminum oxide
(Al2O3) grown by ALD, like Sun. See, e.g., Ex. 1008, Title, Abstract, 462.
Petitioner cites Schmidt’s introduction only for the general teaching that
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back passivation layers typically act as reflectors. Pet. 37–38 (citing
Ex. 1008, 461, 464–65; Banerjee Decl. ¶ 120).
In Patent Owner’s view, Schmidt’s layers are much thicker than
Sun’s: Schmidt teaches a 220 nm-thick layer of thermal SiO2, and a 230 nm-
thick aluminum-oxide/silicon-oxide stack, and by contrast, Sun’s passivation
layers, combined, are only 17 nm thick. PO Resp. 26. According to Patent
Owner, Sun’s passivation layers are “far too thin to perform effective
reflection” alone, and so Sun uses another layer—silicon-nitride layer
108b—as the reflection layer. Id. at 24 (citing Lebby Decl. ¶ 75), 26 (citing
Lebby Decl. ¶ 79).
But Dr. Lebby explained that a 100 nm-thick dielectric layer placed
against a back-metal contact acts as a light-trapping cavity. Lebby Decl.
¶¶ 45–46. And Sun teaches that the first passivation layer has a thickness of
2 nm to 100 nm. Sun ¶ 18. So we disagree with Patent Owner’s argument for
at least the reason that it does not address the full range of thicknesses
contemplated by Sun. See PO Resp. 24, 26.
Even so, the record does not support the argument that thickness alone
determines whether a layer is embodied as the recited reflection layer: Dr.
Lebby explained that he had not seen, nor was he aware of, metrics for
determining whether a layer is reflective. Ex. 1025, 19:16–25; see also Ex.
2004, 248:13–259:3 (Dr. Banerjee’s testimony about “ideal” parameters).
Dr. Lebby testified that “it is not just the thickness” that determines
reflective properties, but “the composition, the refractive index, what its
performance is over wavelengths . . . come into play, too.” Ex. 1025, 147:7–
11; see also supra § II.B (explaining that the recited reflection layer is not
defined by specific parameters). And Schmidt teaches that an aluminum
oxide layer that is 30 nm thick can be part of a stack that reflects light, when
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used in combination with another layer. See Ex. 1008, 464. So, for this
additional reason, we disagree with Patent Owner’s argument that Sun’s
passivation layers are too thin to be reflection layers. PO Resp. 24. Apart
from those passages discussed here and in section II.B supra, we give little
weight to the testimony of Dr. Lebby to the extent that his opinion relies on
Patent Owner’s overly narrow interpretation of the claim. Ex. 2001, 30–33.
In its Reply, Petitioner presents experimental data to purportedly show
how Sun’s passivation layers would perform as a reflector. Pet. Reply 20–
23. Under the construction of “reflection layer” adopted in this Decision, we
need not assess the performance of Sun’s layers individually, in isolation.
See supra § II.B. Therefore, we do not consider these experiments in
reaching our conclusion. So Patent Owner’s arguments about these
experiments are moot. Sur-reply 22–26.
In sum, Petitioner has shown that Sun’s passivation layers are
part of a stack that collectively enhances reflection at the back surface
of the solar cell relative to the incident light. Pet. 37–38. For this
reason, Petitioner has shown that Sun’s passivation layers are
embodied as reflection layers under the construction adopted in this
Decision. See supra § II.B.
Because Petitioner has shown that Sun’s layers are at least one
of the two recited types of layers, Petitioner has shown by a
preponderance of the evidence that the subject matter of claim 6
would have been obvious over Sun alone.
c) The Petition: Claim 6, Sun in view of Schmidt
The Petition characterizes the first challenge as “obvious in view of
Sun” (Pet. 40) and the second as “obvious in view of Sun and Schmidt”
(id. at 54). The citations to Sun and Schmidt are mostly the same. But,
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unlike the rationale based on “Sun alone,” the Sun-Schmidt obviousness
rationale refers to the analysis of claim 3 and also cites a third reference,
Cook, for an “additional motivation to combine Sun and Schmidt.” Id.
(citing Ex. 1020, 55).
In particular, Petitioner’s analysis for claim 3 explains that it would
have been “obvious to use the ALD of Schmidt . . . in the [s]cheme of Sun to
form the aluminum oxide passivation layer.” Id. at 51 (citing Ex. 1005 ¶ 39,
Ex. 1003 ¶ 154). As for the third reference, Petitioner asserts that Cook
provides another reason to combine Sun and Schmidt: maximizing light
trapping. Id. at 54 (citing Ex. 1020, 55).
d) Analysis: Claim 6, Sun in view of Schmidt
As discussed above, we need not consider the performance of Sun’s
layers individually to determine whether the layer is embodied as a
reflection layer. Supra § II.B. Nevertheless, Petitioner’s obviousness
rationale is based on modifying Sun’s layer to maximize the cell’s light-
trapping properties. Pet. 54. That is, although not required by the claim
interpretation adopted in section II.B, Petitioner’s obviousness ground is
based on the reasoning that enhancing reflection of an individual passivation
layer can be desirable. Id.
In particular, we agree with Petitioner that Schmidt teaches designing
the cell’s rear stack to improve light trapping. Ex. 1008, 461, 464–465.
Schmidt shows that a rear passivation layer of aluminum oxide and silicon
oxide (Al2O3/SiOx) can be part of a reflection layer. Id. at 464–465.
Schmidt’s Table II, for example, shows results for an Al2O3/SiOx stack. Id.
at 464. Schmidt refers to Table II’s entries as “rear structures.” Id. Schmidt
states that “[a]ll three rear structures are equally effective reflectors for near-
bandgap photons (Rr = 91%).” Id., quoted in Pet. 38, 54. More generally,
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Schmidt also shows that a solar cell’s rear structure is typically designed to
trap light. Id. at 461 (providing an overview of the prior approaches).
Cook also supports Petitioner’s rationale because Cook teaches using
a reflective surface for light trapping. Ex. 1020, 55. Cook explains that a
highly reflective back surface can reflect unabsorbed photons back into the
cell’s interior. Id. On this record, Petitioner adequately explains why one of
ordinary skill in the art would have been motivated to enhance reflection by
using Schmidt’s teachings to form Sun’s passivation layer. Pet. 53–54.
To the extent that Patent Owner’s arguments about the ground based
on Sun alone are relevant to the Sun-Schmidt combination, we find those
arguments unpersuasive for the same reasons discussed in section II.D.1.b).
Additionally, the argument that Sun’s layers are too thin to trap light (see,
e.g., PO Resp. 24, 28) is unpersuasive for the additional reason that the
argument is moot in light of Petitioner’s proposed modification to Sun to
enhance light trapping (Pet. 51, 54).
As for Cook’s teachings, Patent Owner argues that Cook’s back
surface lacks dielectric layers because it relies solely on a metal-contact
sheet for reflection. PO Resp. 27; see also Sur-reply 28–29 (arguing that
Cook teaches a cell can achieve maximum light trapping with only a rear
metal contact). According to Patent Owner, “Cook provides no motivation to
interpret Sun’s passivation layers as reflection layers.” PO Resp. 28 (citing
Ex. 2001 ¶ 82). Patent Owner argues that Petitioner has not shown a
reasonable expectation of success that Sun’s layers could function in a way
that meets the claim language. Id.5

5 Here, Patent Owner refers to an “antireflection layer.” PO Resp. 28. We
interpret this to mean a reflection layer because the title of the section is
“Sun and Schmidt Do Not Render Obvious a Reflection Layer.” Id. at 27. To
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Yet Petitioner is not proposing to substitute Cook’s teachings into
Sun. Rather, Petitioner is proposing to modify Sun with Schmidt. Pet. 51,
54. Petitioner relies on Cook for the teaching that it would have been
desirable to design a structure to reflect unabsorbed photons back into the
cell’s interior—not for modifying Sun’s cell with Cook’s reflection layer.
Id. (citing Ex. 1020, 55).
Patent Owner argues that it would not have been obvious to “lift
layers out of one design, and throw them into another design” and that
modifying Sun’s layers would have unpredictable results. Sur-reply 28
(citing Ex. 1025, 95:1–14, 91:25–92:20; Ex. 2004, 288:14–21). But bodily
incorporation is not the test for obviousness. Even so, Patent Owner provides
little support for the assertion about unpredictability. See id. For example,
Dr. Lebby provides no evidence or analysis to support this statement.
Ex. 1025, 91–95. Thus, we assign little weight to the testimony of Dr. Lebby
on this point about unpredictability. See Ashland Oil, Inc. v. Delta Resins &
Refractories, Inc., 776 F.2d 281, 294 (Fed. Cir. 1985) (“Lack of factual
support for expert opinion going to factual determinations, however, may
render the testimony of little probative value in a validity determination.”).
For similar reasons, we disagree with Patent Owner’s argument about
textured layers and give little weight to Dr. Lebby’s testimony on this point.
Sur-reply 26–27; Ex. 2001, 33–34. In particular, Patent Owner argues that
Schmidt and Cook cannot be relied upon for the motivation to modify Sun
because both use textured layers. Sur-reply 27, 29. According to Patent
Owner, Petitioner asserts that a cell’s performance is largely attributed to

the extent that Patent Owner intended to state “antireflection layer,” we find
that argument unpersuasive for similar reasons and those discussed in
section II.D.2.
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texturing and, thus, teachings about textured cells are “irrelevant” to Sun’s
flat structures. Id. at 27.
We disagree with Patent Owner because Schmidt states that “[a]ll
three rear structures are equally effective reflectors for near-bandgap
photons (Rr = 91%)”—referring to the structures in Table II. Ex. 1008, 464,
quoted in Pet. 38, 54. The three rear structures are “(i) one batch of cells
keeps the thermally grown SiO2, (ii) the second one is coated by a 130 nm
Al2O3 film and (iii) the third batch is passivated by a stack consisting of a 30
nm Al2O3 layer and a 200 nm thick.” Id. at 462. Schmidt’s silicon nitride
(SiNx) layer, however, is the layer that is textured. See id., Fig. 1. Patent
Owner’s argument (Sur-reply 26–29) does not explain how texturing affects
the reflective performance of these structures, which are not textured but
relied upon by Petitioner in the combination.
As for the structures in Table II, Patent Owner argues that Schmidt
does not teach that the range of thicknesses from 30 nm to 220 nm provide
reflection. Id. at 28. In Patent Owner’s view, “Schmidt teaches that a single
layer of thermal SiO2 should be 220 nm thick, a single layer of aluminum
oxide should be 130 nm thick, and a stack of aluminum oxide/silicon oxide
should be 230 nm thick.” Id. We disagree.
Although Schmidt’s aluminum-oxide/silicon-oxide stack is 230 nm
thick overall, Table II shows that the aluminum-oxide layer is 30 nm thick.
Ex. 1008, 465 (showing “Al2O3 (30 nm)/SiOx (200 nm)”). Because the
aluminum-oxide layer is part of Schmidt’s reflective stack, it is a reflection
layer as understood in the context of the ’525 patent. See supra § II.B.
In Patent Owner’s view, Sun already teaches using a reflection layer
of a-SiNx:H as a light trapping cavity, but Schmidt does not include a
reflection layer made of the same material. Sur-reply 27 (citing
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Ex. 2001 ¶ 80). Patent Owner argues that “Schmidt does not teach or suggest
that a structure like Sun’s—which already has a reflection layer—would
require another reflection layer.” Id. at 27–28 (emphasis in original).
Petitioner, though, need not prove how Schmidt can be incorporated
into Sun to show that one of ordinary skill in the art would reasonably
expect success. See In re Mouttet, 686 F.3d 1322, 1332 (Fed. Cir. 2012).
And as discussed above, the record does not show that an ordinarily skilled
artisan would have viewed individual layers in a stack as reflective or not.
See supra § II.B. Rather, the relevant inquiry in the context of the ’525
patent is how the stack as a whole performs. See id.
In sum, Petitioner has shown that it would have been obvious to use
Schmidt’s teaching to modify Sun’s passivation layers to embody them as
reflection layers that maximize light trapping—although maximizing
performance in this way is not required by the claim. See Pet. 54.
Thus, weighing the evidence of record, we find that a person of
ordinary skill in the art would have combined Sun and Schmidt. This
combination would have been within the level of ordinary skill in the art.
Because Petitioner has shown that at least one of the two recited types
of layers would have been obvious, Petitioner has shown that the subject
matter of claim 6 would have been obvious over Sun and Schmidt.
2. The Antireflection Layer
Petitioner also presents theories of unpatentability of claims 6 and 18
based on the presence of an antireflection layer. As discussed in the claim-
construction section above, we agree with Petitioner that, in claims 6 and 18,
a layer can be a reflection layer if it is “part of” a stack of layers that
suppresses reflection on the front of the solar cell relative to the incident
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light. Supra § II.B. Because nothing more specific is needed to resolve the
issue in this Decision, we do not further construe “antireflection layer.”
a) The Petition: Claim 6, Obviousness over Sun Alone
As discussed above, Petitioner has shown that claim 6 is obvious over
Sun alone for at least the reason that Sun teaches “the passivation layer is
embodied as a reflection layer.” Supra § II.D.1.b). Alternatively, Petitioner
shows that Sun alone teaches that the passivation layer is embodied as an
antireflection layer.
Petitioner asserts that Sun’s “passivation layers” deposited on the
front side of the solar cell would “act as an anti-reflection layer.” Pet. 38
(emphasis added). In particular, Petitioner argues that “[o]ne skilled in the
art would have understood that all the dielectric layers (i.e., 104a, 106a,
108a, altogether) on top of Sun’s ‘photoelectric conversion layer’ 102
should, altogether, have anti-reflection properties to allow light to get into
the ‘photoelectric conversion layer’ (which is the layer that converts incident
light into electricity).” Id. at 39 (citing Ex. 1020, 21; Ex. 1005, Fig. 2; Ex.
1009, ¶ 32; Ex. 1003 ¶ 199) (emphasis added); id. at 40 (discussing “the
overall reflection properties of the entire dielectric stack”). As with the
reflection layer, we emphasize “part of” and “altogether” here because it
shows how Petitioner’s rationale focuses on the collective function of the
stack, not any one layer in isolation. That is, Petitioner considers all three
layers to be part of the antireflection stack and each one to be an
antireflection layer. Tr. 20:4–5.
b) Analysis: Claim 6, Obviousness over Sun Alone
By contrast, Patent Owner essentially argues that the layers should be
considered individually. See PO Resp. 14–28; Sur-reply 2–5; 16–26; Tr.
41:20–42:3. In particular, Patent Owner argues that a deposition reactor’s
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precise conditions affect a material’s optical properties. PO Resp. 19. Patent
Owner argues that “Sun does not disclose calibrating the deposition process
used to deposit its passivation layers to simultaneously accommodate
antireflection.” Id. Patent Owner argues that the optical properties and
thicknesses of a layer must be “chosen” or “specifically fashioned” for
antireflection. Sur-reply 3 (citing Ex. 100, 5:27–38); Sur-reply 14. For the
reasons discussed above in section II.B supra, we disagree that an individual
layer must be “specifically fashioned”, “chosen,” “calibrated,” or
“optimized” to be an antireflection layer. PO Resp. 14–28, Sur-reply 2–5,
14; 16–26; Tr. 41:20–42:3. Also, we give little weight to the testimony of
Dr. Lebby to the extent that his opinion relies on Patent Owner’s overly
narrow interpretation of the claim. Ex. 2001, 19–26.
In Patent Owner’s view, Sun has chosen “a distinct anti-reflection
layer on top of the passivation layers (108a).” separate and apart from the
passivation layers. PO Resp. 6, 19. In particular,
Sun’s silicon oxide/aluminum oxide passivation layers with Patent
Owner’s annotations are shown below. Id. at 14.

Figure 2, above, shows an aluminum oxide layer (purple), a silicon oxide
layer 104a (red), and a silicon substrate (green). Id. Patent Owner argues that
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“Sun relies on a separate layer of silicon nitride 108a (orange) for
antireflection.” Id. at 15.
Petitioner asserts that all dielectric layers on top of Sun’s photoelectric
conversion layer 102 are embodied and act as antireflection layers. Pet. 39.
Like the reflection layer, the ’525 patent supports Petitioner’s position that a
layer is antireflective if it is part of an antireflective stack. Id. at 38–39. And
we agree with Petitioner that the presence of a separate layer of silicon
nitride does not preclude other layers from being antireflection layers.
Id. at 39. Indeed, the fact that Sun’s passivation layers are placed alongside
the layer of silicon nitride only further indicates that the passivation layers
are antireflection layers.
The Banerjee Declaration supports Petitioner’s assertion: Dr. Banerjee
states that “[o]ne skilled in the art would have understood that passivation
layers deposited on the front of the solar cell would have to act as an anti-
reflection layer for proper operation as a solar cell.” Banerjee Decl. ¶ 118
(citing Ex. 1020, 21). According to Dr. Banerjee, the purpose of the other
antireflective layers would be defeated if the passivation layers on the front
side of the solar cell reflected light. Banerjee Decl. ¶ 119.
Patent Owner argues that Petitioner’s argument is based on
impermissible hindsight and the ’525 patent itself. Sur-reply 21. We
disagree. Petitioner’s assertion about the layers above Sun’s photoelectric
conversion layer 102 is supported by Cook’s and Hagino’s discussion of
how the top layer of a solar cell should minimize reflection. Pet. 39 (citing
Ex. 1020, 21). Cook explains that “the top surface through which light
passes must be treated to minimize reflection.” Ex. 1020, 21, quoted in
Pet. 39. According to Cook, the untreated photovoltaic cell reflects light.
Id. at 21–22. Likewise, Hagino’s passivation film on the light-receiving
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surface is antireflective. Ex. 1009 ¶ 33. Here, both teachings align with Dr.
Banjeree’s comments about how a person of ordinary skill in the art would
have understood Sun’s passivation layers must work for the solar cell to
operate effectively. Banerjee Decl. ¶ 118. Thus, we credit the Banerjee
Declaration on this point. See id. ¶¶ 118–119.
Patent Owner argues that Dr. Lebby explains that not all layers in a
solar cell perform antireflection. PO Resp. 20 (citing Lebby Decl. ¶ 64).
According to Patent Owner, “one antireflection layer of a-SinNx:H will
sufficiently reduce reflection such that the other layers in a solar cell may be
designed to address different problems, like passivation.” PO Resp. 20
(citing Lebby Decl. ¶¶ 64–65, Ex. 2002, 81).
But, as discussed above, the record does not indicate that there is a
particular thickness or performance metric that determines whether a layer
was designed to address a problem. See, e.g., Ex. 1025, 19:16–25 (Dr.
Lebby’s testimony about thresholds); Ex. 2004, 250:13–19; Ex. 2004,
248:13–259:3 (Dr. Banerjee’s testimony about “ideal” parameters). Nor does
the patent provide guidance about how to fashion such a layer for a
particular purpose, apart from general statements about thickness and optical
properties. See Ex. 1001, 5:34–38 (discussing thickness), 7:1–10 (discussing
“additional optical properties”). Instead, Petitioner’s reasoning that considers
the layer’s placement relative to the incident light (Pet. 39) has ample
support from Dr. Banerjee, Cook, and Hagino, as discussed above.
In its Reply, Petitioner presents simulation data to purportedly show
how Sun’s passivation layers would perform. Pet. Reply 9–11. As discussed
above, under the construction of “antireflection layer” adopted in this
Decision, we need not assess the performance of Sun’s layers individually,
in isolation. See supra § II.B. Thus, we do not consider these experiments in
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reaching our conclusion, and Patent Owner’s arguments about these
experiments are moot. Sur-reply 17–20.
We find Patent Owner’s arguments about the quarter wave equation
(id. at 9–11) unpersuasive and give less weight to Dr. Lebby’s testimony
about the equation (Ex. 2001, 19–26) because Patent Owner and Dr. Lebby
rely on a narrow interpretation of the claim, as discussed in section II.B.2
supra.
In sum, Petitioner has that shown Sun’s passivation layers are part of
a stack that collectively suppresses reflection at the front surface of the solar
cell relative to the incident light. Pet. 38–39. Thus, Petitioner has shown that
Sun’s passivation layers are embodied as antireflection layers. Id. Because
Petitioner has shown that Sun’s layers are at least one of the two recited
types of layers, Petitioner has shown that the subject matter of claim 6 would
have been obvious over Sun alone.
c) The Petition: Claim 6, Obviousness over Sun and Hagino
Petitioner asserts that claim 6 would have been obvious in view of
Sun and Hagino for the same reasons discussed in connection with Sun
alone. Pet. 66. Petitioner also asserts that “one skilled in the art would have
understood that the silicon oxide/aluminum oxide passivation layers that are
deposited on the front side of the solar cell (104b and 106b) would act as an
antireflection layer, given that Hagino’s ‘passivation film 3A’ on the front
side of the solar cell also [functions] as an antireflection film.” Id. (citing
Ex. 1005, Fig. 2, ¶¶ 23, 39; Ex. 1009 ¶ 32; Ex. 1003 ¶ 187). Petitioner
asserts that Hagino confirms that the additional silicon-nitride antireflection
film on top of the passivation film “does not eliminate the need for the
passivation film to function as an antireflection film.” Pet. 66 (citing
Ex. 1009 ¶ 32, Ex. 1003 ¶ 187).
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Petitioner explains that “[o]ne skilled in the art would have been
motivated to combine Sun and Hagino to maximize solar cell efficiency by
suppressing reflection of incident light at the front side of the solar cell and
also by suppressing recombination by passivation.” Pet. 67 (citing Ex. 1005
¶¶ 7, 39; Ex. 1009 ¶¶ 2, 26–39, 65–72, Fig. 2, Fig. 5H; Ex. 1009, 43–57; Fig.
1; Figs. 3A–3F; Ex. 1003 ¶ 188). Petitioner asserts that Sun and Hagino are
analogous art because each is in the solar-cell field. Pet. 67. Petitioner also
asserts that both are reasonably pertinent to the problem of reducing surface
recombination using silicon-oxide or aluminum-oxide passivation layers. Id.
In Petitioner’s view, this is also the problem that the inventors of the ’525
patent were trying to solve. Id. Petitioner also asserts that, like Sun,
Hagino’s light-receiving silicon-oxide film acts as a chemical passivation
layer. Id. (citing Ex. 1009 ¶ 31; Ex. 1003 ¶ 188).
d) Analysis: Claim 6, Obviousness over Sun and Hagino
Patent Owner argues that Hagino is inapplicable to Sun because
Hagino uses “a fundamentally different structure with different design
constraints.” PO Resp. 21. In particular, Patent Owner argues that Hagino
uses only one passivation layer, which would not “inform” one of ordinary
skill about the properties of Sun’s two-layer passivation stack. Id. at 21–23.
Patent Owner argues that Hagino and Sun use different ALD processes.
Id. at 23 (citing Ex. 1007, 042112-1; Ex. 1008, 465; Ex. 2001 ¶ 71).
According to Patent Owner, Sun designed its passivation layer to have a
specific thickness to passivate the substrate, but Hagino does not specify a
thickness for its layer. PO Resp. 22–23. Patent Owner argues that, in fact,
Sun performs better than Hagino: Sun’s flat solar cell has 19.09% efficiency,
and Hagino’s cell efficiency is 19% at best, with texturing. Sur-reply 13
(citing Ex. 1005, Table II, Ex. 1009 ¶ 72).
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Petitioner, though, does not propose substituting Hagino’s layers in
Sun. Pet. 66. Rather, Petitioner relies on Hagino to show that a passivation
layer can also function as an antireflection layer, even in the presence of
another layer that also performs that function. See id.; see also Pet. Reply 17
(citing Ex. 1003 ¶ 187). Patent Owner’s arguments about the relative
performance of the devices (Sur-reply 13) do not squarely address the reason
that Petitioner relies on Hagino: maximizing a solar cell’s efficiency by
using the passivation layer in two ways.
Hagino supports Petitioner’s assertion that passivation layers can have
a dual function. Pet. 66; see also Pet. Reply 17. In particular, Hagino’s solar
cell has a two-layer dielectric stack: a first passivation layer acts as an
antireflective film, and a second antireflection layer. Ex. 1009 ¶ 39, cited in
Pet. 66, Pet. Reply 17. Hagino’s Figure 2 is reproduced below.

Hagino’s Figure 2, above, shows a solar cell with passivation film 3A under
antireflection film 5. Id. Like Sun, Hagino teaches a silicon-nitride layer on
top of a passivation film. See id. ¶ 55 (“The antireflection film includes . . .
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silicon nitride.”); Banerjee Decl. ¶ 187. Hagino states that “the light-
receiving surface passivation film also functions as an antireflection film.”
Ex. 1009 ¶ 32.
We agree with Petitioner that Hagino teaches that the presence of a
silicon-nitride layer does not preclude a passivation layer from embodying
an antireflection layer. See id. Considering Hagino’s teachings about its
passivation layer’s dual role (id.), we agree with Petitioner that one of
ordinary skill in the art would have been motivated to combine Sun and
Hagino “to maximize solar cell efficiency by suppressing reflection of
incident light at the front side of the solar cell and also by suppressing
recombination by passivation.” Pet. 67.
Patent Owner argues that “Hagino does not teach that using one
antireflection layer is insufficient in general.” PO Resp. 21. In Patent
Owner’s view, “the cited portion of Hagino merely states that in some
embodiments its passivation layer 3A can be formed to act as an
antireflection layer.” Id. (citing Ex. 1009 ¶¶ 27, 37). According to Patent
Owner, Sun’s silicon-nitride layer “alone would nearly eliminate all
reflection, resulting in a high efficiency cell.” PO Resp. 21 (citing Ex. 2002,
81).
We agree with Petitioner’s response to these arguments. Pet. Reply 19
n.6. To support the assertions about Sun’s performance, Patent Owner cites
Dutttagupta’s teachings. PO Resp. 21 (citing Ex. 2002, 81); see also Lebby
Decl. ¶ 67. Duttagupta applies the 70 nm silicon-nitride layer to a substrate
that is textured. Ex. 2002, 81. Yet Sun does not discuss texturing. Accord
Sur-reply 11 (characterizing Sun’s surface as “flat”). Duttagupta teaches that
the texture reduces average reflection from 36.5% to 11.67%. Ex. 2002, Fig.
2, cited in Pet. Reply 18–19. Because Dr. Lebby has not sufficiently
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accounted for Duttagupta’s texturing in concluding that Sun would have a
comparable performance, we give little weight to Dr. Lebby’s testimony on
this point. Ex. 2001 ¶¶ 66–72. That does not mean that Duttagupta or
Hagino, which also uses texturing, are “irrelevant” to Sun. Sur-reply 11–12.
Rather, we agree with Petitioner that, because texturing affects antireflection
(Ex. 2002, Fig. 2), more explanation is needed to support a conclusion that
Duttagupta’s results apply to Sun’s device, which says nothing about
texturing. See Pet. Reply 18–19.
Even so, Petitioner proposes modifying Sun’s layer to “maximize
solar cell efficiency by suppressing reflection” using Hagino’s teachings
about using the passivation layer for antireflection. Pet. 67. The record
supports Petitioner’s assertion that one of ordinary skill in the art would
have chosen the appropriate thickness for a cell’s layers based on how the
layers would function in combination. Pet. Reply 18. Contrary to Patent
Owner’s argument (Sur-reply 11–13, 21–22), Petitioner does not introduce a
new rationale by stating that “it would have been obvious and well within
the knowledge of a Skilled Artisan to select the thickness of that layer based
on the existing antireflection qualities of passivation layers 106a and 104a to
work in conjunction to eliminate reflection.” Pet. Reply 18. Rather, we
understand Petitioner to be making a general point about the law of
obviousness: one need not prove how Hagino can be bodily incorporated
into Sun to show that one of ordinary skill in the art would reasonably
expect success. And, on this point, the case law supports Petitioner. “It is
well-established that a determination of obviousness based on teachings
from multiple references does not require an actual, physical substitution of
elements.” Mouttet, 686 F.3d at 1332.
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Thus, Petitioner has shown that it would have been obvious to
embody Sun’s passivation layers as antireflection layers in view of Hagino’s
teachings. Because Petitioner has shown that Sun’s layers are at least one of
the two recited types of layers, Petitioner has shown that the subject matter
of claim 6 would have been obvious over the Sun-Hagino combination.
3. Claim 18
Claim 18 recites “wherein the chemically passivating passivation
sublayer and the field-effect-passivating passivation sublayer are applied in
such a way that the passivation layer resulting therefrom acts as a reflection
layer or as an antireflection layer.” Ex. 1001, 12:18–21. That is, claim 18
recites limitations similar to those of claim 6, except that claim 18 is a
method reciting that the passivation “acts as” a reflection or antireflection
layer.
But the parties do not argue that the issues in this case turn on the
meaning of “embodied” or “act.” See Pet. 50, 59, 17 (relying on the same
analysis); PO Resp. 18 (stating that the challenges to claim 18 fails for the
same reasons as claim 6); Sur-reply 11–26 (arguing the claims together); Tr.
11:9–20. Petitioner relies on the same analysis for claim 18 as claim 6.
Pet. 50, 59, 71. And these differences between claims 6 and 18 not affect the
claim construction above. Supra § II.B. Thus, for the reasons discussed in
connection with claim 6, Petitioner has shown that the subject matter of
claim 18 would have been obvious in view of the Sun alone, Sun and
Schmidt, and Sun and Hagino. Supra §§ II.D.1–2.
E. Cumulative Challenges to Claims 3, 5, 7, 12, and 14
As noted above in section I.E, Petitioner presents multiple, cumulative
challenges to claims 3, 5, 7, 12, and 14. Because we determine that these
claims are unpatentable in light of Sun (claims 3, 5, and 14) and the Sun-
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Schmidt combination (claims 7 and 12) for the reasons discussed above, we
do not separately assess the patentability of these claims based on the
remaining grounds in this proceeding. 35 U.S.C. § 318(a) (“If an inter partes
review is instituted and not dismissed under this chapter, the Patent Trial and
Appeal Board shall issue a final written decision with respect to the
patentability of any patent claim challenged by the petitioner and any new
claim added under section 316(d).”); see also Beloit Corp. v. Valmet Oy, 742
F.2d 1421, 1423 (Fed. Cir. 1984) (finding that an administrative agency is at
liberty to reach a decision based on a single dispositive issue).

III. CONCLUSION
Petitioner has met its burden to show that claims 1–18 are
unpatentable.
In summary, we find as follows:
Claims
Challenged
35
U.S.C. § Reference(s)
Claims
Shown
Unpatentable
Claims Not
Shown
Unpatentable
1–6, 8–11,
13–16, 18 103(a) Sun
1–6, 8–11,
13–16, 18

3, 6, 7, 12,
18 103(a) Sun, Schmidt
6, 7, 12, 18
5, 7, 12, 14 103(a) Sun, Hoex
6, 17, 18 103(a) Sun, Hagino 6, 17, 18
Overall
Outcome
1–18

IV. ORDER
It is
ORDERED that claims 1–18 of the ’525 patent are unpatentable; and
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FURTHER ORDERED that, because this is a Final Written Decision,
parties to this proceeding seeking judicial review of the Decision must
comply with the notice and service requirements of 37 C.F.R. § 90.2.

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FOR PETITIONER:
Chin-Lee Fukuda
Samuel N. Tiu
Wonjoo Suh
SIDLEY AUSTIN LLP
clfukada@sidley.com
stiu@sidley.com
wsuh@sidley.com

FOR PATENT OWNER:
James M. Glass
Sean Gloth
QUINN EMANUEL URQUHART & SULLIVAN, LLP
jimglass@quinnemanuel.com
seangloth@quinnemanuel.com