INTERNATIONAL BUSINESS MACHINES CORPORATION

Patent Trials and Appeals Board

Jan 8, 2021

2020001962 (P.T.A.B. Jan. 8, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
14/656,287 03/12/2015 Jeehwan Kim YOR920150113US1
(163-881)
8310
49267 7590 01/08/2021
Tutunjian & Bitetto, P.C.
401 Broadhollow Road
Suite 402
Melville, NY 11747
EXAMINER
GOLDEN, ANDREW J
ART UNIT PAPER NUMBER
1726
NOTIFICATION DATE DELIVERY MODE
01/08/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
docketing@tb-iplaw.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte JEEHWAN KIM,
YUN SEOG LEE, and TALIA S. GERSHON
__________

Appeal 2020-001962
Application 14/656,287
Technology Center 1700
____________

Before MICHAEL P. COLAIANNI, GEORGE C. BEST, and
DEBRA L. DENNETT, Administrative Patent Judges.

COLAIANNI, Administrative Patent Judge.

DECISION ON APPEAL
Appellant1 appeals under 35 U.S.C. § 134(a) the Final Rejection of
claims 15–34. We have jurisdiction over the appeal pursuant to 35 U.S.C.
§ 6(b).
We AFFIRM.

1 We use the word “Appellant” to refer to “applicant” as defined in 37
C.F.R. § 1.42. Appellant identifies the real party in interest as International
Business Machines Corp. (Appeal Br. 4).
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STATEMENT OF THE CASE
Appellant’s invention is directed to devices which use absorber layers
comprised of a single crystal chalcogenide compound, such as Cu-Zn-Sn-
S/Se (CZTSSe) (Spec. ¶ 1). The Specification describes the use of CZTSSe-
based absorber layers, which consist of earth-abundant elements, as an
emerging thin film solar cell technology (id. ¶¶ 3, 17). According to the
Specification, single crystal CZTSSe devices may provide higher power
conversion efficiency over polycrystalline versions (id. ¶¶ 18, 19).
Claims 15 and 26 are illustrative (emphases added):
15. A photovoltaic device, comprising:
a first contact layer formed on a first substrate;
an absorber layer including an epitaxially grown single
monocrystal structure including Cu-Zn-Sn-S(Se) (CZTSSe)
placed directly on the first contact layer;
a buffer layer formed in contact with the absorber layer;
and
a transparent conductive contact layer formed over the
buffer layer.
26. The device as recited in claim 15, wherein the absorber
layer includes a Kesterite structure having a (112) single
crystal orientation.
Appellant appeals the following rejections:
1. Claims 15–20, 24, 25, 27, 29–31, 33, and 34 are rejected under 35
U.S.C. § 103 as unpatentable over Liang et al. (US 2013/0344646
A1, published Dec. 26, 2013) (“Liang”) in view of Hong et al. (US
2014/0099749 A1, published Apr. 10, 2014) (“Hong”).
2. Claims 21 and 22 are rejected under 35 U.S.C. § 103 as
unpatentable over Liang, in view of Hong, and further in view of
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3
Hasegawa et al. (US 2013/0247994 A1, published Sept. 26, 2013)
(“Hasegawa”).
3. Claim 23 is rejected under 35 U.S.C. § 103 as unpatentable over
Liang, in view of Hong, and further in view of Schoop et al. (US
2012/0192941 A1, published Aug. 2, 2012) (“Schoop”).
4. Claim 26 is rejected under 35 U.S.C. § 103 as unpatentable over
Liang, in view of Hong, and further in view of Meissner et al. (US
2012/0138136 A1, published June 7, 2012) (“Meissner”), as
evidenced by Chunhong et al., “Electrospun Cu2ZnSnS4
microfibers with strong (112) preferred orientation: fabrication
and characterization,” RSC Adv. (2015) 5:15749–55
(“Chunhong”).
5. Claim 28 is rejected under 35 U.S.C. § 103 as unpatentable over
Liang, in view of Hong, and further in view of Karg (US
2014/0246070 A1, published Sept. 4, 2014).
6. Claim 32 is rejected under 35 U.S.C. § 103 as unpatentable over
Liang, in view of Hong, and further in view of Suzuki et al. (WO
2013/157321 A1, published Oct. 24, 2013, referencing the English
language equivalent US 2015/0118789 A1, published Apr. 30,
2015) (“Suzuki”).
Appellant argues the claims as a group and offers separate arguments
in support of independent claim 15 and dependent claim 26, which are
subject to rejections (1) and (4), respectively (see generally Appeal Br. 7–
17). Claims 16–25 and 27–34 will stand or fall with our analysis of claim
15. 37 C.F.R. § 41.37(c)(1)(iv). Claim 26 will be discussed separately.
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FINDINGS OF FACT & ANALYSIS
We have fully considered all of Appellant’s arguments contained in
the Appeal Brief. We find that the preponderance of the evidence favors the
Examiner’s obviousness conclusion. We agree with the Examiner analysis
and response to arguments provided on pages 16 to 24 of the Answer.
Appellant’s arguments focus solely on the Examiner’s findings with regard
to Liang, Hong, and Meissner (Appeal Br. 9–17). Therefore, we need not
address the Examiner’s findings or conclusions with regard to the combined
teachings of Liang and Hong with Hasegawa, Schoop, Karg, and Suzuki as
they are not in dispute. We add the following analysis for emphasis.
A. Claim 15
With respect to claim 15, the Examiner’s findings and conclusions
regarding Liang and Hong in rejection (1) are located on pages 3 to 4 of the
Final Office Action.
Appellant argues that Hong’s process of growing CZTSSe cannot
create the claimed absorber layer, which is formed as a single monocrystal
structure placed directly on the first contact layer (Appeal Br. 12–14).
The Examiner, however, does not rely on Hong to teach the claimed
location of the absorber layer within a photovoltaic device. Rather, the
Examiner persuasively finds that Liang teaches the limitation of the absorber
layer, which includes CZTSSe, placed directly on the first contact layer
(Ans. 20 (citing Liang ¶ 92; Fig. 3 (depicting absorber layer 306 deposited
directly on back contact layer 304))).
Appellant contends that Hong’s CZTSSe thin film does not share
structural identity with the claimed epitaxially grown single monocrystal
structure including CZTSSe (Final Act. 13). Appellant contends that Hong
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5
teaches annealing the CZTS thin film to increase crystallinity, which implies
that the resulting film is formed as a polycrystalline structure (id. at 12).2
According to Appellant, Hong fails to teach the features of Appellant’s
invention, including the steps of epitaxially growing a single crystal CZTSSe
layer over a single crystal layer and then exfoliating the absorber layer for
transfer to a substrate (id.).
We are not persuaded by these arguments.
Claim 15 is directed to a photovoltaic device end product comprising
an epitaxially grown single monocrystal structure, including CZTSSe,
placed directly on the first contact layer. Appellant’s arguments regarding
Hong’s alleged failure to teach epitaxial growth of the claimed absorber
layer are directed to the process used to form the product.3 In other words,
Appellant contends that claim 15 is product-by-process claim. Assuming,
arguendo, that Appellant is correct, in a product-by-process claim, the
method used to make the product is not determinative because the product
claim is based upon the structural limitations of the product only. In re
Thorpe, 777 F.2d 695, 697 (Fed. Cir. 1985). The end product of claim 15
includes a single monocrystal structure having CZTSSe.

2 Our review of the prosecution file history indicates it is undisputed that
CZTSSe, CZTSe, and CZTS are equivalent. See also Liang ¶ 51 (disclosing
that, “[a]s used herein, ‘CZTSSe’, ‘CZTSe’, and ‘CZTS’ will be defined as
equivalent and will be used interchangeably.”).
3 Even assuming that Hong’s process is distinguishable, the Examiner finds
that Hong teaches forming a CZTS thin film absorber for a solar cell using
metal-organic chemical vapor deposition (MOCVD), which is an epitaxial
growth process (Ans. 18). According to the Examiner, MOCVD is also
known as metal-organic vapour-phase epitaxy (MOVPE) (id.) (Emphasis
added). Appellant has not rebutted these findings.
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Appellant’s arguments lack persuasive merit because Hong explicitly
discloses that the disclosed CZTS thin film “manufacturing method can be
applied to produce large-area monocrystalline materials” (Hong ¶ 35; see
also Ans. 18–19). Appellant’s argument about growing the claimed
absorber layer as a single crystal layer over another single crystal layer, such
as graphene, and exfoliating the absorber layer for transfer to a substrate is
not persuasive because those limitations argued do not appear in the claim.
In re Self, 671 F.2d 1344, 1348 (CCPA 1982) (“Many of appellant’s
arguments fail from the outset because . . . they are not based on limitations
appearing in the claims.”). Therefore, we agree with the Examiner that
Hong teaches an epitaxially grown single monocrystal structure, including
CZTSSe, as required by claim 15 (Ans. 20 (citing Hong ¶ 35)).
We discern no reversible error in the Examiner’s determination that it
would have been obvious to one of ordinary skill in the art at the time of the
invention to grow Liang’s photovoltaic device’s absorber layer, which
includes CZTSSe, by Hong’s single stage MOCVD process to produce a
single monocrystal CZTSSe absorber layer (Final Act. 4 (citing Hong ¶¶ 27,
31–34)).
Thus, based on a preponderance of evidence in this record, we affirm
this rejection of claim 15.
B. Claim 26.
With respect to claim 26, the Examiner’s findings and conclusions
regarding Liang, Hong, Meissner, and Chunhong in rejection (4) are located
on pages 11 to 12 of the Final Office Action.
Appellant argues that Meissner and Chunhong do not teach the
limitation “an absorber layer including an epitaxially grown single
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monocrystal structure including . . . CZTSSe[] placed directly on the first
contact layer,” as recited in claim 15 (Appeal Br. 14–15). Appellant argues
that “an absorber layer including an epitaxially grown single monocrystal
structure including . . . CZTSSe[] having a Kesterite structure epitaxially
grown from a single crystal layer, in accordance with the claimed
arrangements, has inherent crystalline properties (e.g., lattice properties) that
differ from those of the same material being formed via other processes” (id.
at 15). In other words, Appellant distinguishes the claimed absorber layer
based on alleged differences in how known absorber layers were
manufactured.
We are not persuaded by these arguments.
We agree with the Examiner that claims 15 and 26 are directed to a
photovoltaic device and not a method of manufacturing a photovoltaic
device (Ans. 22). At most, each of these claims is a product-by-process
claim. In such claims, alleged differences between the claimed and prior art
methods used to make the product are not dispositive. See Thorpe, 777 F.2d
at 697. Therefore, the claimed CZTSSe absorber is not distinguished from
the prior art’s CZTSSe absorber having a monocrystal structure and a
Kesterite form that was allegedly manufactured by a different process.
Furthermore, the Examiner does not rely on Meissner and Chunhong
to teach the disputed limitations recited in claim 15. Rather, the Examiner
relies upon the combined teachings of Liang in view of Hong to teach these
claim limitations (Ans. 21; see supra § A.).
The Examiner finds that the combined teachings of Liang and Hong
are silent with respect to the crystalline structure possessing a Kesterite form
(Final Act. 11). The Examiner, however, persuasively finds that Meissner
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teaches forming monocrystalline CZTSSe absorbers with a Kesterite
structure (id. at 11 (citing Meissner ¶¶ 10, 24–26); see also Ans. 22–23).
Although Meissner does not explicitly disclose that the Kesterite structure
has a (112) crystal orientation, the Examiner persuasively relies on
Chunhong’s evidence that the thermodynamically preferred growth direction
is along the (112) orientation in CZTS systems with a Kesterite structure
(Final Act. 12 (citing Chunhong 15752)).
We discern no reversible error in the Examiner’s conclusion that it
would have been obvious to one having ordinary skill in the art at the time of
the invention to further modify Liang’s absorber layer, as modified by Hong,
to use Meissner’s single crystal CZTSSe absorber layer, which includes a
Kesterite structure having a (112) single crystal orientation (Ans. 23). We
agree with the Examiner that one of ordinary skill in the art would have been
motivated to do so because Meissner teaches that this semiconductor
material confers improved homogeneity (id. (citing Meissner ¶ 10)).
Thus, based on a preponderance of evidence in this record, we affirm
this rejection of claim 26.
C. Claims 16–25 and 27–34
Appellant’s arguments regarding claims 16–25 and 27–34 also rely on
the same unpersuasive arguments made regarding claim 15 in rejection (1)
(Appeal Br. 9–14). As discussed above, we have affirmed rejection (1) of
claim 15. We, therefore, also affirm rejections (2), (3), (5), and (6) of claims
16–25 and 27–34.
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CONCLUSION
In summary:
Claims
Rejected 35 U.S.C. § Reference(s)/Basis  Affirmed Reversed
15–20, 24,
25, 27, 29–
31, 33, 34
103 Liang, Hong
15–20, 24,
25, 27, 29–
31, 33, 34

21, 22 103 Liang, Hong, Hasegawa 21, 22
23 103 Liang, Hong, Schoop 23
26 103
Liang, Hong,
Meissner,
Chunhong
26
28 103 Liang, Hong, Karg 28
32 103 Liang, Hong, Suzuki 32
Overall
Outcome 15–34
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).
AFFIRMED