Ex Parte Ajmera et al

Board of Patent Appeals and Interferences

Sep 14, 2010

10287476 (B.P.A.I. Sep. 14, 2010)

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.
10/287,476 11/05/2002 Atul Champaklal Ajmera YOR920000373US2 5926
48150 7590 09/15/2010
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA, VA 22182-3817
EXAMINER
PHAM, THANH V
ART UNIT PAPER NUMBER
2894
MAIL DATE DELIVERY MODE
09/15/2010 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 BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte ATUL CHAMPAKLAL AJMERA, CYRIL CABRAL, JR.,
ROY ARTHUR CARRUTHERS, KEVIN KOK CHAN,
GUY MOSHE COHEN, PAUL MICHAEL KOZLOWSKI,
CHRISTIAN LAVOIE, JOSEPH SCOTT NEWBURY, and
RONNEN ANDREW ROY
____________

Appeal 2009-009080
Application 10/287,476
Technology Center 2800
____________

Before KENNETH W. HAIRSTON, JOHN C. MARTIN, and
JOSEPH F. RUGGIERO, Administrative Patent Judges.

RUGGIERO, Administrative Patent Judge.

DECISION ON APPEAL1

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, or for filing a request for rehearing,
as recited in 37 C.F.R. § 41.52, begins to run from the “MAIL DATE”
(paper delivery mode) or the “NOTIFICATION DATE” (electronic delivery
mode) shown on the PTOL-90A cover letter attached to this decision.
Appeal 2009-009080
Application 10/287,476

2
STATEMENT OF THE CASE
Appellants appeal under 35 U.S.C. § 134 from the Final Rejection of
claims 32, 34, 36-39, and 41-57, which are all of the pending claims. Claims
1-31, 33, 35, and 40 have been canceled. We have jurisdiction under
35 U.S.C. § 6(b).
We affirm.2
Rather than reiterate the arguments of Appellants and the Examiner,
we refer to the Appeal Brief (filed October 15, 2008), the Answer (mailed
November 20, 2008), and the Reply Brief (filed January 16, 2009) for the
respective details. We have considered in this decision only those
arguments Appellants actually raised in the Briefs. Any other arguments
which Appellants could have made but chose not to make in the Briefs are
deemed to be waived. See 37 C.F.R. § 41.37(c)(1)(vii).

Appellants’ Invention
Appellants’ invention relates to a semiconductor substrate including a
source and drain formed on respective sides of a gate wherein the source and
drain are raised over a strained silicon layer. The source, drain, and gate are
partially formed of metal disilicide which directly contacts a Si-Ge buffer
layer. (See generally Spec. 8:12–10:2).
Claim 56 further illustrates the invention and reads as follows:

2 This appeal is a result of continuing prosecution in Application Serial No.
10/287,476, filed November 5, 2002. The Examiner’s rejection based on
essentially the same prior art was the subject of an earlier Board decision
(No. 2006-1438; May 4, 2006) before a different panel which affirmed the
Examiner’s rejection of all of the appealed claims. The Examiner has added
an additional prior art reference in support of the rejection of some of the
claims presently on appeal.
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Application 10/287,476

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56. A semiconductor substrate, comprising:
a substrate;
silicide-forming-barrier means formed on said substrate;
a strained silicon layer formed on said silicide-forming-barrier means
and having a source and drain formed therein on respective sides of a gate,
said gate being formed over said strained silicon;
wherein said source, drain and gate are partially formed of a metal
disilicide,
wherein said source and drain contain at least a portion of said
strained silicon film and are raised with respect to said strained silicon film,
and
wherein said metal disilicide directly contacts said silicide-forming-
barrier means.

The Examiner’s Rejections
The Examiner’s Answer cites the following prior art references:
Maa US 5,830,775 Nov. 3, 1998
Meikle US 6,239,492 B1 May 29, 2001
(filed May 8, 1996)
Fitzgerald US 6,555,839 B2 Apr. 29, 2003
(Provisional application filed May 26, 2000)
Claims 56 and 57 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over the combination of Fitzgerald and Maa.
Claims 32, 34, 36-39, and 41-55 stand rejected under 35 U.S.C. §
103(a) as being unpatentable over the combination of Fitzgerald, Maa, and
Meikle.

ISSUES
Based on Appellants’ contentions, as well as the findings and
conclusions of the Examiner, the pivotal issues before us are as follows:
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a) did the Examiner err in concluding that it would have been
obvious to an ordinarily skilled artisan to combine the disilicide formation
teachings of Maa with the strained silicon FET device teachings of
Fitzgerald;
b) did the Examiner err in determining that the structure resulting
from the combination of Fitzgerald and Maa includes a “relaxed” SiGe layer
which acts as a silicon-forming-barrier means; and
c) did the Examiner err in determining that an ordinarily skilled
artisan would have arrived at a device structure in which the metal silicide
directly contacts the “relaxed” SiGe layer by routine experimentation.

PRINCIPLES OF LAW
In rejecting claims under 35 U.S.C. § 103, it is incumbent upon the
Examiner to establish a factual basis to support the legal conclusion of
obviousness. See In re Fine, 837 F.2d 1071, 1073 (Fed. Cir. 1988). In so
doing, the Examiner must make the factual determinations set forth in
Graham v. John Deere Co., 383 U.S. 1, 17 (1966) (stating that 35 U.S.C.
§ 103 leads to three basic factual inquiries: the scope and content of the prior
art, the differences between the prior art and the claims at issue, and the
level of ordinary skill in the art). Furthermore,
“there must be some articulated reasoning with some rational
underpinning to support the legal conclusion of obviousness” . .
. . [H]owever, the analysis 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., 550 U.S. 398, 418 (2007) (quoting In re Kahn,
441 F.3d 977, 988 (Fed. Cir. 2006)).
Appeal 2009-009080
Application 10/287,476

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ANALYSIS
Independent claim 56
With respect to the Examiner’s 35 U.S.C. § 103(a) rejection of
independent claim 56, Appellants initially argue that even if the Fitzgerald
and Maa references were combined as proposed by the Examiner, the
resultant combination would not include the claimed feature of a “silicide-
forming-barrier means formed on said substrate.” According to Appellants
(App. Br. 9-10; Reply Br. 2-3), the Examiner’s analysis does not follow the
standard set forth in MPEP § 2183 for examination of claims in means-plus-
function format. In particular, Appellants contend (id.) that the Examiner’s
analysis does not establish that the SiGe buffer layer of Fitzgerald performs
the function specified in the claims, i.e., acts a barrier to the formation of
silicide.
We do not agree with Appellants. Appellants’ arguments to the
contrary notwithstanding, we find that the Examiner has indeed followed the
guidelines set forth in MPEP § 2183 for examining means-plus-function
limitations. In particular we find no error in the Examiner’s line of
reasoning (Ans. 5-6, 11-13) which finds that the “relaxed” SiGe layer
104/604/804 of Fitzgerald which is buffered between the graded SiGe layer
and the strained Si layer, and has endured the silicidation process taught by
Maa, would perform the claimed function of acting as a barrier to the
formation of silicide. We agree with the Examiner (Ans. 13) that, since this
“relaxed” SiGe layer is formed of the same material by substantially the
same process and in the same location, it will perform the same silicide
forming barrier function as claimed. We further agree with the Examiner
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that Appellants have never demonstrated that the claims are drawn to
specific apparatus distinct from Fitzgerald’s “relaxed” SiGe layer, nor
shown that such layer does not have the silicide-forming-barrier
characteristics as claimed.
We also find unpersuasive Appellants’ arguments that the Examiner’s
proposed combination of Fitzgerald and Maa does not result in the claimed
direct contact of the silicided layer of Fitzgerald with Fitzgerald’s SiGe layer
104/604/804, which the Examiner has identified as the silicide-forming-
barrier means as previously discussed. In Appellants’ view, the Examiner’s
contention that Fitzgerald discloses the claimed direct contact feature is in
direct contradiction to the actual teachings of Fitzgerald. According to
Appellants (App. Br. 12-13; Reply Br. 5-7), Fitzgerald’s silicide layer 530 is
separated from the SiGe layer 604 by the substrate 500 of the source and
drain (Fig. 5I) and, therefore, even if it were obvious to control the thickness
of the related layers as suggested by the Examiner, Fitzgerald’s silicide layer
530 would be separated from and have no direct contact with the SiGe layer
604.
We agree with the Examiner (Ans. 17), however, that there is no basis
for Appellants’ conclusion that the substrate identified by the numeral 500 in
Fitzgerald’s Figure 5 illustrations would be placed on top of the substrate
identified by numeral 608 in Fitzgerald’s Figure 6. To the contrary, our
interpretation of the disclosure of Fitzgerald coincides with that of the
Examiner, i.e., the structures illustrated in Figures 6 and 8 of Fitzgerald are
the starting structures for the gate, source, and drain silicidation process
illustrated in Figures 5A-5I of Fitzgerald along with the accompanying
description at column 4, line 31, through column 5, line 31. It is apparent,
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therefore, that when Fitzgerald’s Figure 6 structure is silicided according to
the Figure 5 silicidation process, the substrate identified by the numeral 500
would actually be the substrate 608 of Figure 6.
We also find no error in the Examiner’s determination that Maa
provides a teaching (col. 10, ll. 1-5) of optimizing the silicidation process
through routine experimentation by controlling the depth or thickness of the
metal silicide layer by adjusting the temperature and the duration of the
annealing steps. We find that an ordinarily skilled artisan would have
recognized from this teaching that, as suggested by the Examiner (Ans. 6, 7,
16), the depth of the silicide layer could be controlled as desired so that it
either i) approaches but does not directly contact the SiGe layer, ii)
penetrates through the surface of the SiGe layer, or iii) directly contacts the
SiGe layer as claimed.
It is noteworthy that, while Appellants’ arguments direct attention to
the claimed direct contact feature, Appellants’ disclosure provides no
indication of the criticality of any such direct contact but, rather, indicates
that, at best, direct contact is merely a preferred result. For example,
Appellants point (App. Br. 7) to Figures 5 and 6 as support for the “directly
contacts” claim language. These figures, however, do not show any direct
contact between the metal disilicide layer and the SiGe layer but, rather, the
metal disilicide layer is separated from the SiGe layer by a “stripe” of
unconsumed strained silicon. The various options for extending the metal
disilicide layer to and into the SiGe layer are discussed in the bridging
paragraph at pages 11 and 12 of the Specification. In our view, this
disclosure confirms that the depth or thickness of the metal silicide layer is a
variable which can be adjusted as desired dependent on particular situations,
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Application 10/287,476

8
a disclosure which comports with what is suggested by Maa (col. 10, ll. 1-5)
as reasoned by the Examiner (Ans. 6, 7, 16).
We also find to be without merit Appellants’ contention (App. Br. 19-
20; Reply Br. 7) that the Examiner, in suggesting that disilicide layer
thickness is a variable which can be optimized through routine
experimentation, has not established that the thickness of the metal disilicide
layer is a result effective variable. To the contrary, Maa indicates that the
thickness of the metal disilicide is indeed a result effective variable by
disclosing, inter alia, that the control of the thickness of the silicide “allows
for formation of ultra-thin source/drain junction regions . . . .” (Maa, col. 9,
ll. 61-64).
Lastly, contrary to Appellants’ contentions (App. Br. 11-12; Reply Br.
4-5) we find that the Examiner’s stated position (Ans. 5) provides a valid
articulated line of reasoning with a rational underpinning to support the legal
conclusion of obviousness for the proposed combination of Fitzgerald and
Maa. See KSR, 550 U.S. at 418. We agree with the Examiner’s finding that
the increased stability provided by the disilicide formation teachings of Maa
(Abstract; col. 1, ll. 55-56)) would be recognized by the artisan as an
obvious enhancement to the strained silicon FET device of Fitzgerald.
For the above reasons, we sustain the Examiner’s 35 U.S.C. § 103(a)
rejection of independent claim 56.

Dependent claim 57
We also sustain the Examiner’s obviousness rejection, based on the
combination of Fitzgerald and Maa, of dependent claim 57. For reasons
similar to those discussed with respect to claim 56, we find no error in the
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Application 10/287,476

9
Examiner’s finding that Maa’s disclosure (col. 10, ll. 1-5) of controlling the
depth or thickness of the silicide layer by adjusting temperature and duration
of the annealing steps would result in the control of the amount by which the
source and drain are raised above the SiGe layer, i.e., the silicide-forming-
barrier means, as claimed.

Claims 32, 34, 36-39, and 41-55
The Examiner’s obviousness rejection of claims 32, 34, 36-39, and
41-55, based on the combination of Fitzgerald, Maa, and Meikle, is also
sustained. We find no error in the Examiner’s application (Ans. 8-9) of the
co-sputtering material deposition teachings of Meikle (col. 2, ll. 28-33) to
the combination of Fitzgerald and Maa. We also find no error in the
Examiner’s determination (Ans. 10-11) that the claimed element thicknesses
and ratios would be arrived at through routine experimentation for reasons
similar to those discussed with respect to claim 56. Appellants’ arguments
(App. Br. 16-23) rely on those asserted against the obviousness rejection of
independent claim 56. We found those arguments to be unpersuasive as
discussed supra.

CONCLUSION OF LAW
Based on the findings of facts and analysis above, we conclude that
the Examiner did not err in rejecting claims 32, 34, 36-39, and 41-57 for
obviousness under 35 U.S.C. § 103(a).

Appeal 2009-009080
Application 10/287,476

10
DECISION
We affirm the Examiner’s decision rejecting claims 32, 34, 36-39, and
41-57 under 35 U.S.C. § 103(a).
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)(v) (2009).

AFFIRMED

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MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD
SUITE 200
VIENNA, VA 22182-3817