Ex Parte Cornfeld

Patent Trial and Appeal Board

Sep 22, 2017

13964774 (P.T.A.B. Sep. 22, 2017)

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.
13/964,774 08/12/2013 Arthur Cornfeld B006Y 9931
41170 7590 09/22/2017
EMCORE CORPORATION
10420 Research Road SE
ALBUQUERQUE, NM 87123-3345
EXAMINER
LUKE, DANIEL M
ART UNIT PAPER NUMBER
2813
MAIL DATE DELIVERY MODE
09/22/2017 PAPER
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.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte ARTHUR CORNFELD1
Appeal 2017-000307
Application 13/964,774
Technology Center 2800
Before PETER F. KRATZ, BEVERLY A. FRANKLIN, and
MICHAEL P. COLAIANNI, Administrative Patent Judges.
COLAIANNI, Administrative Patent Judge.
DECISION ON APPEAL
1 The Applicant is Emcore Solar Power, Inc. Appellant identifies SolAero
Technologies Corp. as the real party in interest (App. Br. 1).
Appeal 2017-000307
Application 13/964,774
Appellant appeals under 35 U.S.C. § 134 the final rejection of claims
1, 2, 5—14, and 16—20. We have jurisdiction over the appeal pursuant to
35 U.S.C. § 6(b).
We AFFIRM.
Appellant’s invention is directed to semiconductor devices such as
multijunction solar cells based on III-V semiconductor compounds including
a metamorphic layer (i.e., metamorphic multijunction solar cells) (Spec.
136).
Claim 1 is illustrative:
1. A method of manufacturing a solar cell comprising:
providing a first substrate;
forming a GaAs contact layer on said first substrate;
forming an upper first solar subcell having a first band
gap on said contact layer;
forming a second solar subcell adjacent to said first solar
subcell and having a second band gap smaller than said first
band gap;
forming a first graded interlayer adjacent to said second
solar subcell, said first graded interlayer having a third band
gap greater than said second band gap;
forming a third solar subcell adjacent to said first graded
interlayer, said third subcell having a fourth band gap smaller
than said second band gap such that said third subcell is lattice
mismatched with respect to said second subcell;
forming a second graded interlayer adjacent to said third
solar subcell, said second graded interlayer having a fifth band
gap greater than said fourth band gap;
forming a lower fourth solar subcell adjacent to said
second graded interlayer, said lower fourth subcell having a
sixth band gap smaller than said fourth band gap such that said
fourth subcell is lattice mismatched with respect to said third
subcell;
mounting a surrogate substrate on top of the fourth solar
subcell;
removing the first substrate; and
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Application 13/964,774
passivating an exposed surface of the contact layer of the
solar cell by exposure to an ammonium sulphide solution or
hydrogen sulfide gas.
Appellant appeals the following rejections:
1. Claims 1, 2, 6—14, 16, 17, and 20 are rejected under 35 U.S.C.
§ 103(a) as unpatentable over Newman (US 2010/0229926 Al, pub.
Sept. 16, 2010) in view of Kagadei (V. A. Kagadei et al. Effect of
Sulfur Modification of GaAs Surface on Parameters of AuGeNi Ohmic
Contacts,) and Eftekhari (G. Eftekhari, Electrical Properties of
Sulfur-Passivated III-V Compound Devices, 67 J. Vacuum, 81—90
(2002)).
2. Claim 5 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Newman in view of Kagadei, Eftekhari, and Lai (Li-Wen Lai et al.,
Performance Improvement of (Nll4)2Sx-Treated III—V Compounds
Multijunction Solar Cell Using Surface Treatment, 155 J.
Electrochem. Soc’y, B1270-73 (2008)).
3. Claims 18 and 19 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Newman in view of Kagadei, Eftekhari, and
Ounadjela (US 2009/0223549 Al, pub. Sept. 10, 2009).
4. Claims 1, 2, 5—14, and 16—20 are provisionally rejected on the ground
of nonstatutory double patenting as being unpatentable over claims 1—
4, 6—14, and 16—19 of copending Application No. 13/954610 in view
of Newman and Kagadei.
5. Claims 1, 2, 6—14, and 16—20 are provisionally rejected on the ground
of nonstatutory double patenting as being unpatentable over claims 1,
6—18, and 20 of copending Application No. 13/921,756 in view of
Newman and Kagadei.
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Application 13/964,774
Appellant does not argue the merits of the provisional double patenting
rejections (4) and (5) other than to state that if the provisional obviousness-
type double patenting rejections are the only rejections left pending in this
appeal after Board review, the Examiner should pass this application to issue
pursuant to the Manual of Patent Examining Procedure § 822.01 (App. Br.
17—18). Because we affirm the Examiner’s § 103 rejection, we summarily
affirm the provisional double patenting rejections. Ex parte Jerg, 2012 WL
1375142, *3 (BPAI 2010) (informative) (“Panels have the flexibility to
reach or not reach provisional obviousness-type double-patenting rejections.
See Ex parte Moncla, 95 USPQ2d 1884 (BPAI 2010)”).
FINDINGS OF FACT & ANAFYSIS
Appellant argues independent claims 1 and 16 together as a group
(App. Br. 5—10). We select claim 1 as representative of the group. Claims
2, 6-14, 17, and 20 will stand or fall with our analysis of the rejection of
claim 1.
The Examiner finds that Newman teaches all the limitations of claim
1, except for passivating the exposed surface of the contact layer of the solar
cell by exposure to an ammonium sulphide solution or hydrogen sulfide gas
(Final Act. 3—4). With regard to the step of passivating the exposed surface
of the contact layer of the solar cell, the Examiner finds that Kagadei teaches
that it is known to passivate a GaAs surface prior to ohmic contact formation
(Final Act. 5). The Examiner finds that Newman’s Figure 11 shows forming
an ohmic contact on a surface of the GaAs contact layer (id.). The Examiner
finds that Kagadei teaches to dip contact layer in a sulfide solution in order
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Application 13/964,774
to passivate the layer (id.). The Examiner finds that Eftekhari teaches using
ammonium sulphide to passivate a GaAs layer (id.). The Examiner
concludes that it would have been obvious to passivate the contact layer of
Newman according to the technique taught by Kagadei in order to improve
ohmic contact parameters (id.). The Examiner concludes that it would have
been obvious to try ammonium sulphide as the sulfur-containing solution in
Newman as taught by Kagadei as it is a predictable use of a prior art element
(i.e., ammonium sulfide) according to its established function (i.e.,
passivating a GaAs layer) (Final Act. 5).
Appellant argues that Kagadei is directed to passivation of a doped
GaAs with no suggestion of passivation of a solar cell, particularly
Newman’s inverted metamorphic multijunction (IMM) solar cell (App. Br.
8). Appellant contends that the IMM solar cell includes highly complex
structures with a multitude of layers having a wide variety of compositions
as disclosed by Newman (App. Br. 7). Appellant argues that the different
compositions and complexity of structure would not have suggested that
passivating Newman’s IMM solar cell with Kagadei’s passivating solution
would have yielded a functional solar cell (App. Br. 8). Appellant contends
that the Examiner fails to provide articulated, credible reasoning as to why
one of ordinary skill in the art would consider the treatment of an IMM solar
cell with a passivating solution to be a predictable solution for improving
ohmic contact parameters of an IMM solar cell (App. Br. 9). Appellant
argues that although not predictable, Appellant is able to achieve an increase
in efficiency of an IMM solar cell by passivating the solar cell (App. Br. 9—
10).
Claim 1 recites in relevant part:
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Application 13/964,774
mounting a surrogate substrate on top of the fourth solar cell;
removing the first substrate; and
passivating an exposed surface of the contact layer of the solar cell by
exposure to an ammonium sulphide solution or hydrogen sulfide gas.
Claim 1 requires that after forming four solar cells and graded layers,
attaching a surrogate substrate to the fourth solar cell and removing the
substrate used as the initial substrate (i.e., first substrate) on which the four
solar cells and graded layers are formed. After the first substrate is removed,
the exposed surface of the contact layer is passivated using either
ammonium sulphide or hydrogen sulfide. The Specification describes that
the buffer layer 102 and etch stop layer 103 are removed so leave contact
layer 104 exposed (Spec. Tflf 161—164). The contact layer 104 is then
passivated by dipping the wafer into an ammonium sulphide solution to form
a passivated layer 602 (Spec. 1165; Fig. 10B). Grid lines 501 are deposited
on the passivated surface of the contact layer 104 (Spec. 1166). The claim
requires passivating the contact layer surface only.
With this claim construction in mind, the Examiner finds that Kagadei
teaches the desirability of passivating a GaAs contact layer with a sulfide
before deposition of ohmic contact metallization in order to provide an
effective method for contact parameter improvement (Kagadei § 1 at 361).
Eftekhari teaches that ammonium sulfide is common sulfide used for
passivating GaAs contacts (Eftekhari § 1 at 81—82). Figure 10 of Newman
show the solar cell after the first substrate and etch stop layer 103 has been
removed from the contact layer. (Newman, Figs. 9 & 10,1110). Newman
teaches a step where the contact layer is exposed before putting down grid
lines. In light of Kagadei’s and Eftekhari’s teachings to passivate GaAs
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contact layers to improve contact properties, it would have been obvious to
treat Newman’s contact layer once the etch stop layer is removed.
Appellant’s argument regarding the complexity and difference in
composition of the various layers in an IMM solar cell are not persuasive.
The passivation of the contact layer occurs while the other layers are
covered by the contact layer, so the interaction of the passivation layer with
the layers that comprise the solar cell would not have been an issue.
Although the edges of the layers of the solar cell may be treated with the
passivation solution as the wafer is dipped into the passivating solution as
argued by Appellant, Newman teaches that the solar cells are formed by
etching annular channels 510 and 511 down to the metal layer (Reply Br. 3-
4; Newman 1118, Figs. 13A, 13B & 15). In other words, the edges of the
wafer that are treated by the passivating liquid are not ultimately part of the
final solar cell. Appellant’s argument that the passivating solution may
affect the internal parts of the layer is mere attorney argument without any
substantiating evidence (Reply Br. 4).
Regarding dependent claim 5 under rejection (2), Appellant makes the
same unpersuasive arguments regarding claim 1 except that Appellant is
comparing Newman’s inverted metamorphic solar cell (IMM) to Lai’s III-V
compound tandem-type solar cell (App. Br. 11—16).
Claim 5 depends from claim 1 and recites “wherein there is a window
layer directly adjacent to the contact layer, and further comprising
passivating the window layer.” Appellant’s Figure 10A shows window layer
105 directly adjacent to contact layer 104. Appellant’s Figure 13 shows that
the contact layer 104 is etched to expose the window layer 105 and the
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window layer is passivated to form a passivated layer 602. Accordingly,
claim 5 only adds that the window layer is passivated.
The Examiner finds that Newman’s Figure 12 shows an embodiment
where the window layer 105 is exposed after the contact layer 104 is etched
during the processing of the solar cells (Ans. 4—5). The Examiner finds that
Newman’s Figure 12 includes a window layer having the same composition
as Lai’s window layer (i.e., AllnP) (id.) The Examiner finds that Lai teaches
that the passivating effects occur at the surface of the window layer (Ans. 5).
The Examiner finds that the surface passivation would occur irrespective of
the internal layers of the solar cell (id.)
The Examiner has established that based upon the teachings of
Newman, Kagadei, Eftekhari, and Lai, one of ordinary skill in the art would
have passivated the window layer in addition to passivating the contact layer
in order to improve the properties of the ohmic contact layer and to reduce
the surface states thereby improving efficiency (Final Act. 5, 8). Appellant’s
argument regarding the effect of passivation on the edges of the various
layers that make up the solar cell is not persuasive for the reasons discussed
with regard to the rejection of claim 1. The Examiner’s rejection provides
articulated reasoning and rationale underpinning as to why the ordinary
skilled artisan would passivate the contact and window layers of Newman in
light of the teachings of Kagadei, Eftekhari, and Lai.
Regarding rejection (3), Appellant relies on unpersuasive arguments
made regarding claim 1 (App. Br. 17). On this record, we affirm the
Examiner’s § 103 rejections.
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DECISION
The Examiner’s decision is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(l)(iv).
ORDER
AFFIRMED
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