Ex Parte Rohatgi et al

Patent Trial and Appeal Board

Aug 5, 2016

12758571 (P.T.A.B. Aug. 5, 2016)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
121758,571 04/12/2010
23859 7590 08/09/2016
Ballard Spahr LLP
SUITE 1000
999 PEACHTREE STREET
ATLANTA, GA 30309-3915
FIRST NAMED INVENTOR
Ajeet Rohatgi
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
ATTORNEY DOCKET NO. CONFIRMATION NO.
19439.0014U3 5228
EXAMINER
BARTON, JEFFREY THOMAS
ART UNIT PAPER NUMBER
1757
NOTIFICATION DATE DELIVERY MODE
08/09/2016 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):
USpatentmail@ballardspahr.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Exparte AJEET ROHATGI, JI-WEON JEONG, KENTA NAKAYASHIKI,
VIJA Y YELUNDUR, DONG SEOP KIM, and MOHAMED HILALI1
Appeal2015-000965
Application 12/758,571
Technology Center 1700
Before ADRIENE LEPIANE HANLON, WESLEY B. DERRICK, and
CHRISTOPHER C. KENNEDY, Administrative Patent Judges.
DERRICK, Administrative Patent Judge.
DECISION ON APPEAL
Appellants appeal under 35 U.S.C. § 134 from the Examiner's
maintained rejections under 35 U.S.C. § 103(a) of claims 41-60 and 62-81.
We have jurisdiction pursuant to 35 U.S.C. § 6.
We AFFIRM.
CLAIMED SUBJECT MATTER
Appellants' claimed invention is directed to fabrication methods to
provide a solar cell. Claims 41 and 60 are the sole independent claims.
1 Georgia Tech Research Corporation is identified as the real party in
interest. Appeal Br. 2.
Appeal2015-000965
Application 12/758,571
Independent claim 41 is illustrative:
41. A method for fabricating a solar cell comprising:
providing a substrate doped to have a first conductivity;
forming an emitter layer doped to have a second
conductivity at a first side of the substrate, wherein the first
conductivity is opposite the second conductivity;
forming an antireflection layer comprising hydrogen on
the emitter layer;
screen-printing one or more contacts on the antireflection
layer;
screen-printing a contact layer on a second side of the
substrate opposite the first; and
enhancing a bulk minority carrier lifetime of the substrate,
compnsmg:
subjecting the substrate to a rapid belt co-firing process in
a belt furnace in accord with a predetermined temperature profile
to:
electrically connect the one or more contacts to the
emitter layer through the antireflection layer;
form a uniform back surface field layer between the
contact layer and the substrate;
release hydrogen from the antireflection layer; and
enhance the transfer of the released hydrogen to
defects in the substrate to passivate the defects;
wherein the predetermined temperature profile
compnses:
a temperature ramp-up stage, wherein, during the
temperature ramp-up stage, the temperature of the
substrate is increased at a rate ranging from about 50 °C/s
to about 100 °C/s;
a temperature holding stage of about five seconds or
less; and
a temperature ramp-down stage, wherein, during the
temperature ramp-down stage, the temperature of the
substrate is decreased at a rate ranging from about 50 °C/s
to about 100 °C/s.
Appeal Br. (Claims Appendix) 14-15.
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Application 12/758,571
REJECTIONS
The Examiner maintains rejections under 35 U.S.C. § 103(a) of:
Claims 41--44, 46, 49-53, 56-60, 62-64, 66, 69-73, and 76-81 over
Jeong 2001,2 Jeong 2002,3 and Biro;4
Claims 45, 54, 55, 74, and 75 over Jeong 2001, Jeong 2002, and Biro,
further in view ofNagahara; 5
Claims 47 and 67 over Jeong 2001, Jeong 2002, and Biro, further in
view of Salami;6
Claims 48 and 68 over Jeong 2001, Jeong 2002, and Biro, further in
view of Rand; 7 and
Claim 65 over Jeong 2001, Jeong 2002, and Biro, further in view of
Watabe. 8
DISCUSSION
Appellants proffer argument as to independent claim 41, and also set
forth the same argument as to independent claim 61. Compare Appeal Br.
5-9 to Appeal Br. 9-13. Appellants rely on the dependency from these
claims for the patentability of all other claims. Appeal Br. 9, 12-13. We
2 Jeong et al., Enhanced Silicon Solar Cell Performance by Rapid Thermal
Firing of Screen-Printed Metals, 48(12) IEEE Trans. Electron. Devices,
2836--41 (Dec. 2001).
3 Jeong et al., RAPID THERMAL PROCESSING TO ENHANCE PECVD SIN-
lNDUCED HYDROGENATION IN HIGH-EFFICIENCY EFG SILICON SOLAR CELLS,
IEEE, 250-53 (2002).
4 Biro et al. (US 2003/0183491 Al, published October 2, 2003).
5 Nagahara et al. (US 4,737,197, issued April 12, 1988).
6 Salami et al. (US 5,928,438, issued July 27, 1999).
7 Rand et al. (US 5,266,125, issued November 30, 1993).
8 Watabe et al. (US 2004/0065362 Al, published April 8, 2004).
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find claim 41 to be representative and will decide the appeal as to all claims
as a group. 37 C.F.R. § 41.37(c)(l)(iv).
"[T]he Examiner bears the initial burden, on review of the prior art or
on any other ground, of presenting a prim a facie case of unpatentability." In
re Oetiker, 977 F.2d 1443, 1445 (Fed. Cir. 1992). To prevail in an appeal to
this Board, Appellant must adequately explain or identify reversible error in
the Examiner's rejection. See 37 C.F.R. § 41.37(c)(l)(iv) (2012); see also In
re Jung, 637 F.3d 1356, 1365-66 (Fed. Cir. 2011) (explaining that even if
the Examiner had failed to make a prima facie case, it has long been the
Board's practice to require an Appellant to identify the alleged error in the
Examiner's rejection).
Upon consideration of the evidence and opposing contentions of the
Appellants and the Examiner, we are unpersuaded of harmful error in the
Examiner's decision. 9 We add the following.
Appellants contend that the Examiner has failed to establish that it
would have been obvious to one of ordinary skill in the art at the time of
invention to enhance a bulk minority carrier lifetime of the substrate by
subjecting the substrate to a rapid belt co-firing process in a belt furnace to a
predetermined temperature profile comprising a ramp-up stage with
temperature increasing at about 50 °C/s to about 100 °C/s, a temperature
holding stage of five seconds or less, and a temperature ramp-down stage
with temperature decreasing at about 50 °C/s to about 100 °C/s. See,
generally, Appeal Br.
9 We refer to the Non-Final Office Action filed August 22, 2013, the Appeal
Brief filed April 21, 2014, and supplemented May 29, 2014, and the
Examiner's Answer mailed August 14, 2014.
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Application 12/758,571
The Examiner relies on Jeong 2001 for its teaching of a method of
making a solar cell by co-firing a substrate, including, inter alia, a
temperature ramp-up in which the substrate temperature is increased
between 10 °C/s and 100 °C/s and temperature holding for one second. Ans.
3, 12 (citing Jeong 2001 2837 iii! 2-3; 2838 iJ 1, Section B). The Examiner
reasonably determines the substrate is then cooled, although Jeong 2001 is
silent as to particulars of the temperature ramp-down stage. Ans. 3, 12-13.
The Examiner also finds Jeong teaches belt furnaces provide high
throughput to reduce costs. Ans. 12 (citing Jeong 20012837,iJ3).
The Examiner relies on Jeong 2002 for its teaching that a faster
temperature ramp-down increases hydrogen retention and, therefore, defect
passivation compared to slower temperature ramp-down passivation. Ans.
3--4, 13 (citing Jeong 2002 251 iJ 4). The Examiner determines that Jeong
2002 establishes the temperature ramp-down stage is a result effective
variable. Ans. 3--4, 13.
The Examiner relies on Biro for its disclosure of a belt furnace for
fabrication of solar cells that is capable of rapid temperature processing.
Ans. 4, 13 (citing Biro iii! 1, 17, 45, Fig. 1). The Examiner further
determines de facto that providing a belt furnace capable of rapid thermal
processing including both increasing and decreasing temperatures would
have been within the ambit of the skilled artisan at the time of invention.
Ans. 16.
The Examiner concludes it would have been obvious at the time of the
invention to use a belt-line furnace capable of RTP to co-fire solar cells
using fast temperature ramp-up, temperature hold, and fast temperature
ramp-down profiles as set forth in the claims for the benefit of high
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throughput to produce solar cells with increased hydrogen passivation. Ans.
13. The Examiner concludes the recited temperature ramp-up is prima facie
obvious because the rate of temperature increase is encompassed by the
range of rates disclosed by Jeong 2001. Ans. 3, 12. The Examiner
concludes the recited temperature ramp-down is prima facie obvious because
it is a result effective variable for improving passivation and no more than
routine experimentation would be required to arrive at the claimed
parameters. Ans. 4, 13.
Appellants contend that the specific parameters of the temperature
profile, in combination, enhance the retention of hydrogen at defects and
thereby improve the bulk minority carrier lifetime of the substrate. Appeal
Br. 6 (citing Spec. 14, 1. 16 to 15, 1. 5, by reference to US 2010/0233840,
iii! 86-89). Appellants' position, however, is not a cogent argument that the
Examiner erred reversibly, particularly where Jeong 2001 discloses similar
improvements in fill factors and back surface recombination (Ans. 13-14,
citing Jeong 2840) and it is not contested that Jeong 2002 teaches that a fast
cooling rate in R TP enhances the retention of hydrogen at the defects (see,
e.g., Appeal Br. 7).
Appellants proffer arguments as to each of Jeong 2001, Jeong 2002,
and Biro, but fail to squarely address the relied on combination as set forth
by the Examiner. Because the rejection is based on what the combination of
teachings would have suggested to one of ordinary skill in the art at the time
of the invention, Appellants' arguments are unpersuasive of reversible error.
In re Keller, 642 F.2d 413, 425 (CCPA 1981) ("[T]he test is what the
combined teachings of the references would have suggested to those of
ordinary skill in the art."). It is axiomatic that "one cannot show non-
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obviousness by attacking references individually where ... the rejections are
based on combinations of references." Id. at 426.
In regard to Jeong 2001, Appellants' arguments emphasize that the
disclosed co-firing scheme that includes a ramp-up rate of about 50 °C/s to
about 100 °C/s is not conducted in a beltline furnace and there is no
particulars as to the ramp-down stage. Appeal Br. 6-7. Appellants then
further contend that the disclosed improvements in Voe and Al-BSF saturate
when the ramp-up rate exceeds 10 °C/s and that one of ordinary skill in the
art would not have been motivated to increase the ramp-up rate to that
claimed. Appeal Br. 7.
We do not find these arguments persuasive of reversible error where
Jeong 2001 discloses a range of ramp-up rates-between 10 °C/s and
100 °C/s-that encompass the claimed rate and, while not necessary to
provide the particularly disclosed benefits, it is evident that the ramp-up
rates exceeding 10 °C/s also provide the disclosed improvements Voe and
Al-BSF. A reference is good for all that it teaches to a person of ordinary
skill in the art. See, e.g., Merck & Co., Inc. v. Biocraft Labs, Inc., 874 F.2d
804, 807 (Fed. Cir. 1989).
In regard to Jeong 2002, Appellants' arguments emphasize that
despite "teach[ing] that 'a fast cooling rate in RTP enhances the retention of
hydrogen at the defects' and that 'fast ramp-up during RTP firing is believed
to improve Al-BSF and contacts,"' Jeong 2002 does not teach these with a
beltline furnace and does not disclose the actual cooling rates used. Appeal
Br. 7. Appellants contend that identifying the claimed ramp-down rate is
more than a matter of routine experimentation, arguing the claimed ramp-up
rate, holding period, and ramp-down rate are critical to achieve the enhanced
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bulk minority carrier lifetime of the substrate. Appeal Br. 7 (citing Spec. 14,
1. 16 to 15, 1. 5, by reference to US 2010/0233840, iii! 86-89)). Appellants
further contend that there is no motivation to arrive at the claimed ramp-
down rate or to believe such a ramp-down would be successful, arguing
there are many risks and potential consequences that can occur under some
conditions. Appeal Br. 7-8.
We do not find these arguments persuasive of reversible error where
the Examiner relies on the cited disclosure to show that the temperature
ramp-down rate is a result effective variable-not for the specific cooling
rates used-and Appellants provide no persuasive evidence that arriving at a
working or optimal value would require more than routine experimentation.
In re Pearson, 494 F.2d 1399, 1405 (CCPA 1974) ("Attorney's argument
... cannot take the place of evidence").
Similarly, absent evidence, we find Appellants' reliance on possible
difficulties or problems that may occur under some conditions insufficient to
establish one of ordinary skill in the art would not have been motivated to
optimize conditions, including the temperature ramp-down rate, or that they
would lack a reasonable expectation of success. "Obviousness does not
require [an] absolute predictability of success ... all that is required is a
reasonable expectation of success." In re 0 'Farrell, 853 F.2d 894, 903-04
(Fed. Cir. 1988). Further, Appellants' arguments fail to properly "take
account of the inferences and creative steps that a person of ordinary skill in
the art would employ" in overcoming difficulties in combining the teachings
of the cited references. KSR Int'! Co. v. Teleflex Inc., 550 U.S. 398, 418
(2007).
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In regard to Biro, Appellants argue that the cited disclosure of a
transport system to transport to-be-processed elements through a high-
temperature zone fails to teach, suggest, or otherwise disclose using the
transport system to achieve a temperature ramp-down rate as recited in the
claims. Appeal Br. 8 (citing Biro iii! 1, 41 ).
We do not find Appellants' argument as to Biro persuasive of
reversible error because-focusing narrowly on the explicit disclosure of
Biro-it both fails to address what the combined references would have
suggested to those of ordinary skill in the art (Keller, 642 F.2d at 425), and
to properly "take account of the inferences and creative steps that a person of
ordinary skill in the art would employ" in overcoming difficulties in
combining the teachings of the cited references (KSR, 550 U.S. at 418).
Further, it is well established that in evaluating references, "it is proper to
take into account not only the specific teachings of the references but also
the inferences which one skilled in the art would reasonably be expected to
draw therefrom" (In re Preda, 401F.2d825, 826 (CCPA 1968)), and one
such reasonable inference is that a disclosed apparatus for RTP is capable of
increasing and decreasing temperatures absent evidence otherwise (Ans. 16).
Appellants fail to direct us to any evidence that there would be any difficulty
in providing a rapid temperature processing belt furnace capable of
achieving temperature ramp-down rates as recited in the claims. See,
generally, Appeal Br.
For the reasons above, it follows that we are not persuaded that the
Examiner's determination is unsupported by the applied prior art and/or is
otherwise based on teachings that are insufficient to support the conclusion
of obviousness.
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It further follows that we do not find Appellants' further argument
that the Examiner relied on impermissible hindsight persuasive of reversible
error. Appeal Br. 8-9. If the Examiner has articulated a reason having
rational underpinnings for making a proposed modification or combination
of prior art teachings, then that articulated reasoning demonstrates the
combination is not based on hindsight. See In re Kahn, 441 F.3d 977, 988
(Fed. Cir. 2006) (requiring "some articulated reasoning with some rational
underpinning to support the legal conclusion of obviousness") (cited with
approval inKSR, 550 U.S. at 418).
On this record, accordingly, we are not persuaded the Examiner has
erred reversibly in determining that one of skill in the art, at the time of the
invention, armed with the cited prior art, would have been led to the claimed
invention.
It follows we affirm the Examiner's decision rejecting claims 41-60
and 62-81.
CONCLUSION
The Examiner's rejections of the claims under 35 U.S.C. § 103(a) are
AFFIRMED.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § l.136(a)(l).
AFFIRMED
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