Ex Parte Wochner et al

Patent Trial and Appeal Board

Aug 12, 2014

12674299 (P.T.A.B. Aug. 12, 2014)

UNITED STATES PATENT AND TRADEMARKOFFICE
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.
12/674,299 02/19/2010 Hanns Wochner WAS1059PUSA 5673
22045 7590 08/12/2014
BROOKS KUSHMAN P.C.
1000 TOWN CENTER
TWENTY-SECOND FLOOR
SOUTHFIELD, MI 48075
EXAMINER
DUNLAP, CAITLIN NOELLE DENNI
ART UNIT PAPER NUMBER
1711
MAIL DATE DELIVERY MODE
08/12/2014 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 HANNS WOCHNER, CHRISTIAN GOSSMANN, and
HERBERT LINDNER
____________

Appeal 2013-001348
Application 12/674,2991
Technology Center 1700
____________

Before TERRY J. OWENS, BEVERLY A. FRANKLIN, and
ELIZABETH M. ROESEL, Administrative Patent Judges.

ROESEL, Administrative Patent Judge.

DECISION ON APPEAL

Appellants appeal under 35 U.S.C. § 134 from the Examiner’s
rejection of claims 7-14 and 17-22. We have jurisdiction under
35 U.S.C. § 6.

1 According to Appellants, the Real Party in Interest is Wacker Chemie AG.
App. Br. 1.
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STATEMENT OF THE CASE
Claims 7 is representative of the subject matter on appeal and is set
forth below (emphasis added):
7. A process for purifying polysilicon to remove metal
contaminants, comprising the steps of:
a) initially precleaning the polysilicon in at least one
stage with an oxidizing cleaning solution comprising
hydrofluoric acid, nitric acid and hexafluorosilicic acid to
form precleaned polysilicon,
b) main cleaning the precleaned polysilicon in a further
stage with a main cleaning solution comprising nitric acid and
hydrofluoric acid to form purified polysilicon, and,
c) following main cleaning, hydrophilizing the purified
polysilicon in a further stage with an oxidizing cleaning
solution
wherein that the acid from the main cleaning step is
reused in the precleaning step, and wherein the purifying
process is free from HCl and H2O2.
The prior art relied upon by the Examiner in rejecting the claims on
appeal is:
Wochner et al. US 6,309,467 B1 Oct. 30, 2001
Yoneya et al. US 6,444,589 B1 Sept. 3, 2002
Pirooz et al. US 5,516,730 May 14, 1996
Hansen et al. US 5,445,679 Aug. 29, 1995
Gilbert N. Lewis & Arthur Edgar, The Equilibrium Between Nitric Acid,
Nitrous Acid And Nitric Oxide, 33 J. AM. CHEM. SOC’Y 292 (1911)
(“Lewis”).
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THE REJECTIONS
1. Claims 7-10, 17-19, 21, and 22 are rejected under
35 U.S.C. § 103(a) as being unpatentable over Wochner in view of Yoneya
and Lewis.
2. Claims 11-14 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Wochner and Yoneya, as applied to claims 7-10, and
further in view of Pirooz.
3. Claim 20 is rejected under 35 U.S.C. § 103(a) as being unpatentable
over Wochner and Yoneya, as applied to claim 7, and further in view of
Hansen.

ANALYSIS
Claims 7-10, 17-19, 21, and 22
Appellants’ claim 7 is directed to a process for purifying
polycrystalline silicon (“polysilicon”). It is undisputed that Wochner
teaches a three-step process for cleaning polysilicon, including precleaning,
main cleaning and hydrophilizing and that steps (b) and (c) of Appellants’
claim 7 are disclosed by Wochner. Regarding step (a) and the final
“wherein” clause of claim 7, the Examiner finds that Wochner teaches “a
variety of acids” for use in the precleaning step and that Wochner’s
disclosure “includes [A]ppellant[s’] embodiment of a solution comprising
hydrofluoric acid and nitric acid, but not containing hydrochloric acid or
hydrogen peroxide.” Answer 3, citing Wochner, 2:60-3:3. Regarding the
penultimate “wherein” clause and step (a), the Examiner acknowledges that
Wochner teaches neither reuse of acid from the main cleaning step in the
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precleaning step, nor use of hexafluorosilicic acid in the precleaning step,
but finds that adding these features to Wochner would have been obvious in
view of Yoneya. Id. at 3-4, citing Yoneya, 1:25-31 and 7:5-29. As detailed
below, the Examiner’s evidence establishes a prima facie case of
obviousness, which Appellants have failed to convincingly rebut. App. Br.
4-13; Reply Br. 2-4.
Regarding the composition of the precleaning solution, the Examiner
correctly finds that Wochner discloses hydrofluoric acid and nitric acid as
possible components. Answer 3; Wochner, 2:3-6 (process of etching
polycrystalline silicon with a mixture of nitric acid and hydrofluoric acid is
“widely used”); 2:60-3:6. The correctness of that finding is further
supported by Appellants’ admission that “HF and HNO3 have been used for
purifying wafers for many years.” Reply Br. 2. Like the Examiner, we are
not persuaded by Appellants’ argument regarding the number of
combinations of acids that are possible based on Wochner’s disclosure.
Compare App. Br. 6 and Reply Br. 4 with Answer 7-8. Wochner discloses
hydrofluoric acid and nitric acid for the same purpose as claimed by
Appellants. The fact that Wochner also discloses many other possible
combinations of acids does not support nonobviousness. Merck & Co., Inc.
v. Biocraft Labs., Inc., 874 F.2d 804, 807 (Fed. Cir. 1989) (that reference
“discloses a multitude of effective combinations does not render any
particular formulation less obvious,” especially where “the claimed
composition is used for the identical purpose taught by the prior art”); In re
Susi, 440 F.2d 442, 445 (CCPA 1971) (obviousness rejection affirmed where
the disclosure of the prior art was “huge, but it undeniably include[d] at least
some of the compounds recited in appellant’s generic claims and [was] of a
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class of chemicals to be used for the same purpose as appellant’s additives”).
We are likewise not persuaded by Appellants’ argument regarding
teaching away. Compare App. Br. 7-8 and Reply Br. 3-4 with Answer 8-9.
Appellants have shown no error in the Examiner’s finding that Wochner’s
Tables 1 and 2 do not teach away from using hydrofluoric acid and nitric
acid in a precleaning solution. Answer 9. Even if we accept Appellants’
contention that Wochner teaches that precleaning “with other than HF/HNO3
is absolutely necessary,” Reply Br. 4, that contention does not support
patentability of Appellants’ claims, which permit the use of other cleaning
agents, except for HCl and H2O2. Wochner’s teaching that cleaning agents
other than hydrofluoric acid and nitric acid are preferred and, in some
instances, provide better results, is insufficient to rebut the Examiner’s
finding of obviousness. Even though they are not taught as preferred,
hydrofluoric acid and nitric acid are nevertheless expressly disclosed as
components that can be used in a precleaning solution. Wochner, 2:60-3:6.
Merck, 874 F.2d at 807 (“in a section 103 inquiry, ‘the fact that a specific
[embodiment] is taught to be preferred is not controlling, since all
disclosures of the prior art, including unpreferred embodiments, must be
considered,’” quoting In re Lamberti, 545 F.2d 747, 750 (CCPA 1976)); In
re Susi, 440 F.2d at 446 n.3 (“We cannot accept the suggestion that one is
significantly ‘taught away’ from a ‘particularly preferred embodiment’ by
the suggestion (whether true or false) that something else may be even
better.”).
Regarding the reuse of acid from the main cleaning step in the
precleaning step and the use of hexafluorosilicic acid in the precleaning step,
we agree with the Examiner that modifying Wochner to include these
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features would have been obvious in view of Yoneya. Answer 3-4; Yoneya,
1:55-64, 2:12-17, 7:10-12, 7:22-26. Like the Examiner, we are not
persuaded by Appellants’ argument that Yoneya is non-analogous art.
Compare App. Br. 9-12 and Reply Br. 5-7 with Answer 9-10. We apply the
following standard articulated by our reviewing court:
Two separate tests define the scope of analogous prior art:
(1) whether the art is from the same field of endeavor,
regardless of the problem addressed and, (2) if the reference is
not within the field of the inventor’s endeavor, whether the
reference still is reasonably pertinent to the particular problem
with which the inventor is involved.
In re Klein, 647 F.3d 1343, 1348 (Fed. Cir. 2011).
We find that Yoneya is from the same field of endeavor as the
claimed subject matter and that, even if the fields of endeavor are different,
Yoneya is still reasonably pertinent to the particular problem with which the
inventors are involved. Both Yoneya and the claimed subject matter relate
to processing silicon for use in the manufacture of semiconductor devices.
Yoneya, 1:11-23; Spec. 1:10-13. More specifically, both Yoneya and the
claimed subject matter relate to a process for treating silicon with a solution
of nitric acid and hydrofluoric acid -- a process that both Yoneya and the
inventors call “etching.” Compare Yoneya, 1:6-8 (“a method . . . for etching
silicon by applying an etchant containing nitric acid and hydrofluoric acid to
the silicon”) with Spec. 3:6-9 (“polycrystalline silicon is etched with a
mixture of nitric acid and hydrofluoric acid”). We further find that Yoneya,
like the inventors, deals with solving a problem of minimizing the
consumption of acid and the associated cost of the etching process.
Compare Yoneya, 1:28-39 with Spec. 4:23-25, 6: 2-3, 6:8-20. We therefore
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concur with the Examiner that “recycling of an acid solution for reuse,” as
taught by Yoneya, “would be obvious to one of ordinary skill in the art for
the purposes of economy and efficiency so as to limit the amount of fresh
solution required and decrease the total cost of the cleaning process.”
Answer 10.
We are similarly not persuaded by Appellants’ argument that reuse of
etching solution would be “counter-intuitive” and “akin to washing a salt-
spattered automobile with salt water.” App. Br. 7, 12, 13; Reply Br. 7.
Appellants have shown no error in the Examiner’s finding that “reuse of a
cleaning solution until the concentration of contaminants is too high within
that cleaning solution to properly clean further substrates is within the
abilities of one of ordinary skill in the art.” Answer 10. Appellants’
argument fails for the additional reason that it is not based on any limitation
appearing in the claims. Whereas Appellants contend that it is “counter-
intuitive to reuse an etching solution containing meal [sic, metal]
contaminants to remove metal contaminants,” App. Br. 12, Appellants’
claim 7 requires reuse of “the acid from the main cleaning step,” not reuse of
a solution containing metal contaminates. In re Self, 671 F.2d 1344, 1348
(CCPA 1982) (“appellant’s arguments fail . . . because . . . they are not based
on limitations appearing in the claims”).
We are unconvinced by Appellants’ arguments regarding unexpected
results because they are unsubstantiated. First, Appellants argue that “an
HF/HNO3 solution also containing H2SiF6 . . . [s]urprisingly . . . is more
powerful than the use of HF/HNO3 alone” and that “[t]he H2SiF6 increases
metal removal.” App. Br. 10. The only evidence cited by Appellants –
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Spec. 5:10-26 – does not support their assertions. Instead, the Specification
merely states that the inventive composition “leads to very good results,”
Spec. 5:12, with “values just as good as . . . a solution of HF/HCl/H2O2,” id.
at 5: 20-21, and that performance is “not impaired” by the presence of
hexafluorosilicic acid, id. at 5:25. Appellants cite no evidence showing that
H2SiF6 improves the cleaning performance of an HF/HNO3 solution. Next,
Appellants argue that their process “provided a surprising and unexpected
improvement over Wochner.” App. Br. 13. The only evidence cited by
Appellants is Comparative Example 1. Contrary to Appellants’ argument,
there is no “side-by-side comparison” between Appellants’ claimed
invention and Wochner. Compare App. Br. 13 with Spec. 6-8. Although
Applicants’ Comparative Example 1 purports to correspond to Wochner’s
example 1, Appellants’ Example 1 is not commensurate in scope with the
claimed process. In contrast to Appellants’ claim 7, in Example 1 “[t]he
precleaning step and the main cleaning step were effected in separate acid
circuits,” Spec. 7:7-8 (emphasis added), with no reuse of the acid from the
main cleaning step and no indication that the precleaning solution contains
hexafluorosilicic acid. Appellants’ cited evidence fails to support their
assertion of unexpected results. See In re Dill, 604 F.2d 1356, 1361 (CCPA
1979) (“The evidence presented to rebut a prima facie case of obviousness
must be commensurate in scope with the claims to which it pertains.”)
Finally, Appellants assert in reply that they “have shown . . . in inventive
Example 1, that metal contaminant removal using spent HF/HNO3 from
main cleaning is more effective than the Wochner process.” Reply Br. 7,
citing Comparative Example 2 [sic, 1]. Appellants’ Comparative Example 1
and Example 1 do not support this assertion for the reasons just explained.
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Accordingly, Appellants have failed to discharge their burden of coming
forward with evidence to support their assertions of unexpected results. In
re Klosak, 455 F.2d 1077, 1080 (CCPA 1972) (“the burden of showing
unexpected results rests on he who asserts them”).
Regarding claim 19, we agree with the Examiner that the term “flows
directly” does not distinguish the claimed process from Yoneya. Compare
App. Br. 14 with Answer 11. When given its “broadest reasonable
construction consistent with the specification,” In re ICON Health &
Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007), “flows directly” does
not exclude intervening steps or apparatus for regenerating the cleaning
solution. The Specification describes this aspect of the invention as a
“cascade” in which “the waste acid comprising HF, HNO3/HNO2 and H2SiF6
which arises from the main cleaning step is used again in the precleaning
step.” Spec. 6:16-18. “Cascade” suggests multiple stages, like those of a
waterfall. See MERRIAM-WEBSTER, http://www.merriam-
webster.com/dictionary/cascade (last visited Aug. 8, 2014). The
Specification further teaches, in Example 2, that “[t]o adjust any deviating
acid concentrations, the required acid can be metered in as necessary.”
Spec. 8:20-22. The Specification’s description of a “cascade” and “metering
in” of additional acid are inconsistent with Appellants’ contention that
“flows directly” excludes an intervening regeneration step, like that
disclosed in Yoneya. Appellants have therefore failed to rebut prima facie
obviousness of claim 19.
Regarding claim 8, we agree with the Examiner that an HNO3
concentration of 5 to 35% in the precleaning step would have been obvious
based on Wochner and Yoneya for the reasons stated by the Examiner.
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Answer, 11-12. Additionally, we note that Wochner discloses a cleaning
solution containing “8 to 70% w/w nitric acid,” Wochner, 3:65-66, which
fully encompasses Appellants’ claimed range. Appellants have cited no
evidence to support separate patentability of claim 8.
Claims 11-14
Regarding claims 11-14, the Examiner finds that Pirooz teaches a
method of forming a hydrophilic layer on a silicone substrate by exposing it
to an aqueous ozone solution and that it would have been obvious to perform
the hydrophilizing step taught by Wochner using the method taught by
Pirooz. Answer, 6, citing Pirooz, 2:63-57; see also Pirooz, 1:59-62. We
agree with the Examiner’s finding and are unconvinced by Appellants’
arguments that Pirooz is non-analogous art and that there would be no
incentive to use the hydrophilization technique of Pirooz in the process of
Wochner, App. Br. 15, for the reasons stated by the Examiner. Answer, 12.
Additionally, we note that Pirooz and the claimed subject matter are from
the same field of endeavor and that Pirooz is reasonably pertinent to the
particular problem with which the inventors are involved, as evidenced by
the fact that Pirooz, like the inventors, teach a process for cleaning silicon.
Compare Pirooz, 1:6 with Spec. 1:6-8. See In re Klein, 647 F.3d at 1348.
Claim 20
Regarding claim 20, the Examiner finds that Hansen teaches a method
for cleaning polysilicon by exposing it to an aqueous bath of HF through
which ozone is bubbled and that it would have been obvious to include the
additional cleaning step taught by Hansen before the hydrophilizing step
taught by Wochner. Answer 6-7, citing Hanson, 3:36-56. We agree with
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that finding and are not convinced by Appellants’ arguments that Hansen is
not relevant and does not teach subsequent hydrophilization with ozone,
App. Br. 16, for the reasons stated by the Examiner. Answer 12-13. We
additionally note that the subsequent step of submerging polysilicon in a
water bath through which ozone is bubbled, Hansen, 3:53-56, is
indistinguishable from the hydrophilization step claimed in Appellants’
claims 11-14.

CONCLUSION OF LAW AND DECISION
The rejections are 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)(1).

AFFIRMED
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