Ex Parte Wai et al

Board of Patent Appeals and Interferences

Sep 30, 2008

11038683 (B.P.A.I. Sep. 30, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte CHIEN M. WAI,
HIROYUKI OHDE,
and STEPHEN J. KRAMER
____________

Appeal 2008-3963
Application 11/038,683
Technology Center 1700
____________

Decided: September 30, 2008
____________

Before CHUNG K. PAK, PETER F. KRATZ and LINDA M. GAUDETTE,
Administrative Patent Judges.

PAK, Administrative Patent Judge.

DECISION ON APPEAL
This is a decision on an appeal under 35 U.S.C. § 134 from the
Examiner's final rejection of claims 1 through 25, all of the pending claims
in the above-identified application. We have jurisdiction pursuant to 35
U.S.C. § 6.
We AFFIRM.

Appeal 2008-3963
Application 11/038,683

STATEMENT OF THE CASE
The subject matter on appeal is directed to methods of treating
semiconductor substrates retained proximate the top interior surface of a
reaction chamber utilizing supercritical fluids (Spec. 1, paras. 0001 and
0012-0014). Details of the appealed subject matter are recited in
representative claims 1, 8, and 18 reproduced below1:
1. A method of treating a semiconductor substrate, comprising:

providing an apparatus comprising a reaction chamber; the reaction
chamber including an interior periphery that comprises a bottom region, a
top region, and one or more sidewall regions between the bottom region and
top region; the reaction chamber being oriented in a gravitational field such
that the field pulls from the top region toward the bottom region;

attaching a semiconductor substrate to one of the regions of the
interior periphery other than the bottom region; and

treating the attached semiconductor substrate by exposing the
semiconductor substrate to a supercritical fluid having one or more reactants
dispersed therein.

8. A method of treating a semiconductor substrate, comprising:
providing an apparatus comprising a reaction chamber; the reaction
chamber comprising an interior periphery that includes a bottom half and a
top half; the reaction chamber being oriented in a gravitational field such
that the field pulls from the top half toward the bottom half;

1 Appellants have presented substantive arguments for patentability of claims
1, 8, and 18 (App. Br. 9-15). Therefore, for purposes of this appeal, we select
claims 1, 8, and 18 and decide the propriety of the grounds of rejection set
forth in the Answer based on these representative claims consistent with 37
C.F.R. § 41.37(c)(1) (vii) (2005).

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Application 11/038,683

retaining a semiconductor substrate within the top half of the interior
periphery; and

while the semiconductor substrate is retained within the top half of the
interior periphery, exposing the semiconductor substrate to a supercritical
fluid having one or more reactants dispersed therein to treat the
semiconductor substrate.

18. A method of treating a semiconductor substrate, comprising:
providing an apparatus comprising a reaction chamber; the reaction
chamber comprising a bottom interior surface and a top interior surface; the
reaction chamber being oriented in a gravitational field such that the field
pulls from the top interior surface toward the bottom interior surface;

retaining a semiconductor substrate proximate the top interior surface;
the substrate having surface which is to be treated and said substrate surface
facing downwardly within the reaction chamber toward the bottom interior
surface;

heating the retained semiconductor substrate; and

while the semiconductor substrate is retained and heated, exposing the
semiconductor substrate surface to a supercritical fluid having one or more
reactants dispersed therein to treat the semiconductor substrate surface.

As evidence of obviousness of the appealed subject matter, the
Examiner has proffered the following prior art references:
Kroneberger 6,287,385 B1 Sep. 11, 2001
Olgado 6,736,408 B2 May 18, 2004
Sasaki 2004/0250747 A1 Dec. 16, 2004

Appellants’ admission at pages 1 through 3 of the Specification (hereinafter
referred to as “the admitted prior art”).

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Application 11/038,683

The Examiner has rejected claims 1 through 25 under 35 U.S.C. §
103(a) as unpatentable over the combined teachings of Sasaki and the
admitted prior art.
Appellants appeal from the Examiner’s decision rejecting the claims
on appeal under 35 U.S.C. § 103(a).

PRINCIPLES OF LAW, ANALYSIS AND ISSUE

Under 35 U.S.C. § 103, the factual inquiry into obviousness requires a
determination of: (1) the scope and content of the prior art; (2) the
differences between the claimed subject matter and the prior art; (3) the level
of ordinary skill in the art; and (4) secondary considerations, if any. Graham
v. John Deere Co., 383 U.S. 1, 17-18 (1966). “[A]nalysis [of whether the
subject matter of a claim would have been prima facie obvious] need not
seek out precise teachings directed to the specific subject matter of the
challenged claim, for a court can take account of the inferences and creative
steps that a person of ordinary skill in the art would employ.” KSR Int’l Co.,
v. Teleflex, Inc., 127 S. Ct. 1727, 1740-41 (2007); ); see also DyStar
Textilfarben GmbH & Co. Deutschland KG v. C.H. Patrick Co., 464 F.3d
1356, 1361 (Fed. Cir. 2006) (“The motivation need not be found in the
references sought to be combined, but may be found in any number of
sources, including common knowledge, the prior art as a whole, or the
nature of the problem itself…“); In re Bozek, 416 F.2d 1385, 1390 (CCPA
1969)(“Having established that this knowledge was in the art, the examiner
could then properly rely, as put forth by the solicitor, on a conclusion of
obviousness ‘from common knowledge and common sense of the person of
ordinary skill in the art without any specific hint or suggestion in a particular
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Application 11/038,683

reference.’”). The common knowledge imputed to the level of one of
ordinary skill in the art includes Appellant’s admission regarding what was
known at the time of the invention. See In re Nomiya, 509 F.2d 566, 570-71
(CCPA 1975) (the admitted prior art in an Applicant’s Specification may be
used in determining the patentability of a claimed invention); see also In re
Fout, 675 F.2d 297, 301 (CCPA 1982) (“[i]t is not unfair or contrary to the
policy of the patent system that appellants’ invention be judged on
obviousness against their actual contribution to the art”).
Here, Appellants do not dispute the Examiner’s finding that:
Sasaki describes a method for treating a semiconductor
substrate comprising: providing a reactive chamber having a
ceiling (claimed top region), a bottom and sidewall regions and
the chamber is oriented in a gravitational field (earth
gravitational field), which would pulls the ceiling region toward
the bottom (fig. 2A; paragraph [0074]); attaching the substrate
to the ceiling of the chamber and treating the substrate by
exposing it to a reactive gas mixture (paragraph [0075]).
[Compare Ans. 3 with App. Br. 4-13 and Reply Br.1-8]

Rather, Appellants contend that one of ordinary skill in the art would not
have been led to employ the claimed supercritical fluid having one or more
reactants dispersed therein in Sasaki’s semiconductor processing chamber as
required by claims 1, 8, and 18 (App. Br. 4-14 and Reply Br. 1-8).
Therefore, the dispositive question is: Would one of ordinary skill in
the art have been led to employ the claimed supercritical fluid having one or
more reactants dispersed therein in Sasaki’s semiconductor processing
chamber as required by claims 1, 8, and 18? On this record, we answer this
question in the affirmative.
We find that Sasaki teaches that “[t]he thin film of Group III nitride
single crystal can be formed on the [semiconductor] substrate, e.g., by metal
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Application 11/038,683

organic chemical vapor deposition (MOCVD)…” (p. 3, para. 0062)
(emphasis added). Although Sasaki does not mention employing the
claimed supercritical fluid, the Examiner finds (Ans. 3 and 5) that
[T]he Admited prior art shows that using supercritical fluid…in
the manufacturing of a semiconductor substrate, such as etching
or depositing, is well known to one skilled in the art at the time
of the invention (pages 1-3 of the specification).

….
[T][he Admitted prior art teaches that supercritical fluid can
have higher diffusion coefficients than conventional solvents,
which can enhance chemical reactions occurring therein (page 1
of the specification, paragraph 0003).
….
Supercritical fluids possess property of gas and have high
diffusivity and known to use in numerous applications in
semiconductor processing including deposition of substances
over semiconductor surfaces. It also enhances chemical
reactions occurring therein (admitted prior art, page 1 of the
specification, paragraphs 0002, 0003, 0005). [Emphasis added.]
Appellants have not disputed the Examiner’s finding that the above
information in the Background of the Invention section of the Specification
was known to those skilled in the art at the time of the invention (Compare
Ans. 3-5 with App. Br. 4-14 and Reply Br. 1-8).
Given the above undisputed facts, we are constrained to agree with the
Examiner that one of ordinary skill in the art would have been led to employ
a mixture of the claimed supercritical fluid and Sasaki’s reactant gas in
Sasaki’s semiconductor processing chamber, with a reasonable expectation
of improving deposition of a thin film of Group III nitride single crystal on
the semiconductor substrate.
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Application 11/038,683

In reaching this determination, we note Appellants’ arguments
directed to possible detrimental intermingling of a reactive gas from a crystal
generation region in a material supply region in Sasaki’s reaction chamber
due to a supercritical fluid having a higher diffusion coefficient than
conventional solvents (Reply Br. 4-6). However, we find that Sasaki, in the
embodiment referred by Appellants, introduces a reactant gas directly to the
semiconductor substrate via a reactive gas inlet pipe 23 so that GaN powder
evaporated from a crucible 28 reacts with nitrogen in the reactive gas on the
semiconductor substrate (p. 4, paras. 0074 and 0075, and Fig. 2). Consistent
with this teaching, one of ordinary skill in the art would have been led to
introduce both the reactant gas and the supercritical fluid directly to the
targeted semiconductor substrate to promote their reaction and deposition
(diffusivity) on the semiconductor substrate, rather than anywhere near the
material supply region.
Accordingly, based on the totality of record relied upon by the
Examiner and Appellants, including due consideration of Appellants’
arguments, we determine that the preponderance of evidence weighs most
heavily in favor of obviousness of the subject matter recited in the claims on
appeal within the meaning of 35 U.S.C. § 103 (a).

ORDER
In view of the foregoing, the decision of the Examiner is affirmed.

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Appeal 2008-3963
Application 11/038,683

TIME PERIOD
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).
AFFIRMED

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