Ex Parte LIU et al

Patent Trials and Appeals Board

Jun 18, 2019

14048244 - (D) (P.T.A.B. Jun. 18, 2019)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
14/048,244 10/08/2013
30423 7590 06/20/2019
Seed IP Law Group LLP/ST US Originating
701 FIFTH A VE
SUITE 5400
SEATTLE, WA 98104
FIRST NAMED INVENTOR
QINGLIU
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.
12AL1008US01/816063.469 1036
EXAMINER
GARCES, NELSON Y
ART UNIT PAPER NUMBER
2814
NOTIFICATION DATE DELIVERY MODE
06/20/2019 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):
USPTOeAction@SeedIP.com
pairlinkdktg@seedip.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte QING LIU and NICOLAS LOUBET
Appeal2018-005594 1
Application 14/048,244
Technology Center 2800
Before JEFFREY T. SMITH, JEFFREY B. ROBERTSON,
and MICHAEL G. McMANUS, Administrative Patent Judges.
SMITH, Administrative Patent Judge.
DECISION ON APPEAL
This decides an appeal under 35 U.S.C. § 134 from the September 7,
2017 final rejection of claims 1, 3, 7-9, 11, 14--16 and 23-33. We have
jurisdiction under 35 U.S.C. § 6.
1 Appellant is the Applicant, STMicroelectronics, Inc., which is also
identified as the real party in interest. (App. Br. 2).
Appeal2018-005594
Application 14/048,244
Appellant's invention is generally directed to methods of forming
semiconductor devices comprising forming a shallow trench isolation (STI)
region between a p-channel metal-oxide semiconductor field-effect transistor
(pMOSFET) and an n-channel metal-oxide semiconductor field-effect
transistor (nMOSFET). (Spec. ,r,r 7-12). Claim 1 illustrates the subject
matter on appeal and is reproduced below from the appendix to the Appeal
Brief:
1. A method, comprising:
forming a buried oxide stack on a semiconductor wafer, the
buried oxide stack including a first oxide layer, a nitride layer,
and a second oxide layer;
forming a semiconductor layer of a first semiconductor material
on the second oxide layer;
forming first and second channel regions in the semiconductor
layer by:
forming a second semiconductor layer of a second
semiconductor material on a surface of the first channel region;
forming a masking layer on a surface of the second channel
reg10n;
oxidizing the second semiconductor layer to drive the second
semiconductor material into the first semiconductor material in
the first channel region; and
preventing, by the nitride layer, the second semiconductor
material from penetrating into the semiconductor wafer during
the oxidizing to block further oxidation of the first oxide layer;
forming an isolation trench between the first and second
channel regions, with the isolation trench extending through
and abutting respective sidewalls of the first oxide layer, the
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Application 14/048,244
nitride layer, and the second oxide layer, the isolation trench
extending at least partially into the semiconductor wafer; and
forming a dielectric body in the isolation trench.
The Examiner maintains the following rejections from the Final
Office Action for our review:
I. Claims 1, 3, 8, 9, 11, 15, 16, 23, 24, and 26-33 rejected under 35
U.S.C. § I03(a) as obvious over the combination of Applicants
Admitted Prior Art (AAPA)2, Khakifirooz (US 2012/0217561 Al,
published Aug. 30, 2012) and Bourdelle (US 8,309,426 B2, issued
Nov. 13, 2012).
II. Claims 7, 14, and 25 rejected under 35 U.S.C. § I03(a) as obvious
over the combination of AAP A, Khakifirooz, Bourdelle, and Cheng
(US 2013/0146975 Al, issued June 13, 2013).
The complete statement of the rejections on appeal appear in the Final
Office Action. (Final Act. 2-15).
OPINION
Appellant presents substantive arguments addressing claim 1. (App.
Br. 20-27). Appellant contends independent claims 11 and 23 are patentable
for the same reasons as independent claim 1. (App. Br. 28-29). Appellant
addresses Rejection II by stating Chang "fails to overcome these deficiencies
of the AAPA, Khakifirooz, and Bourdelle." (App. Br. 28). We will address
independent claim 1 as argued by Appellant. Any claim not separately
2 Specification ,r,r 5-6; Figures 1-2.
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Application 14/048,244
argued will stand or fall with its independent claim 1.
Having considered the respective positions advanced by the Examiner
and Appellant in light of this appeal record, we affirm the Examiner's
rejection for the reasons set forth in the Answer to the Appeal Brief and
Final Office Action appealed from, which we adopt as our own. We
highlight and address specific findings and arguments for emphasis as
follows.
The Examiner found AAP A teaches a method of forming a buried
oxide stack that differs from the claimed invention by failing to describe the
buried oxide as comprising a stack including a first and a second oxide layer,
and a nitride layer; forming an isolation trench between the first and second
channel regions with the isolation trench extending through and abutting
respective sidewalls of the first oxide layer, the nitride layer, and the second
oxide layer, the isolation trench extending at least partially into the
semiconductor wafer; forming a dielectric body in the isolation trench.
(Final Act. 3). Addressing these differences, the Examiner found
Khakifirooz describes buried oxide as comprising a stack including a first
and a second oxide layer, a nitride layer; and forming an isolation trench
between the first and second channel regions. (Final Act. 3--4). The
Examiner determined it would have been obvious to form a buried stack
comprising an oxide/nitride/oxide layer in the process of AAPA to adjust the
threshold voltage of the semiconductor devices as taught by Khakifirooz.
(Final Act. 4 ). The Examiner found the combination of AAP A and
Khakifirooz failed to disclose the isolation trench required by the claimed
invention. (Final Act. 4 ). Addressing this difference, the Examiner found
Bourdelle teaches forming a semiconductor device wherein a shallow trench
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Application 14/048,244
isolation (STI) extends through the buried oxide stack and into the
semiconductor wafer. (Final Act. 4--5). The Examiner found Bourdelle is
concerned with forming STI regions which avoid the Bird's Beak Effect-
the increase in the thickness of the BOX layer in the areas close to the edges
of a trench-that would result in a significant deterioration of the
performance of the finished product. (Final Act. 5; Bourdelle col. 1, 11. 38-
48). The Examiner concludes:
It would have been obvious at the time of the invention to one
of ordinary skill in the art to include the STI of Bourdelle in the
device AAP A/Khakifirooz to separate and isolate different individual
transistors from each other and to avoid the Bird's Beak Effect that
otherwise would result in a significant deterioration of the
performance of the finished device.
(Final Act. 5).
Appellant argues:
None of the cited references contemplate the claimed
advantages of the nitride layer in terms of "preventing, by the nitride
layer, the second semiconductor material from penetrating into the
semiconductor wafer during the oxidizing to block further oxidation
of the first oxide layer."
(App. Br. 25).
Appellant argues Khakifirooz teaches only the use of an oxide-nitride-
oxide (ONO) layer for a different purpose, to adjust the threshold voltage of
semiconductor devices, not to "prevent the second semiconductor material
from penetrating into the semiconductor wafer during the oxidizing to block
further oxidation of the first oxide layer," as recited by independent claim 1.
(App. Br. 23-24).
These arguments are not persuasive because a prima facie case of
obviousness does not require that the applied prior art recognize and address
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Application 14/048,244
the specific problem upon which the inventor was working. In re Dillon,
919 F.2d 688, 693, 1901---02 (Fed. Cir. 1990) (en bane), cert denied, 500
U.S. 904 (1991). The discovery of an additional advantage by applicant
does not make the claims patentable. See In re Kronig, 539 F. 2d 1300,
1304 (CCPA 1976) and In re Heck, 699 F.2d 1331, 1332-33 (Fed. Cir.
1983). A person of ordinary skill in the art would have modified the method
of the AAP A to include a buried oxide stack having an ONO layer to adjust
the threshold voltage of the semiconductor devices as determined by the
Examiner. Appellant has not disputed that Khakifirooz teaches the use of an
ONO layer adjusts the threshold voltage of semiconductor devices.
Appellant argues the combination of AAP A, Khakifirooz, and
Bourdelle fails to teach or suggest an STI region extending through and
abutting respective sidewalls of the first oxide layer, the nitride layer, and
the second oxide layer, the STI region extending at least partially into the
semiconductor wafer, as required by independent claim 1. (App. Br. 25).
Appellant argues Bourdelle only teaches an isolation trench that extends
through a silicon surface layer and a single layer and does not teach or
suggest a STI that abuts sidewalls of such a nitride layer or second oxide
layer. (App. Br. 25-26). Appellant also argues the modification of
Khakifirooz by including in isolating trench would have disrupted the
uniform and continuous buried dielectric layer. (App. Br. 26).
Appellant's arguments are not persuasive of reversible error. In KSR
Int'! Co. v. Teleflex Inc., 550 U.S. 398, 419-20 (2007) the Supreme Court
observed that:
In determining whether the subject matter of a ... claim is
obvious, neither the particular motivation nor the avowed
purpose of the patentee controls. What matters is the objective
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Application 14/048,244
reach of the claim. If the claim extends to what is obvious, it is
... [ unpatentable] under § 103. One of the ways in which a
patent's subject matter can be proved obvious is by noting that
there existed at the time of the invention a known problem for
which there was an obvious solution encompassed by the
patent's claims.
See also Wyers v. Master Lock Co., 616 F.3d 1231, 1238 (Fed. Cir. 2010)
("The Supreme Court's decision in KSR . .. directs us to construe the scope
of analogous art broadly," stating that "familiar items may have obvious
uses beyond their primary purposes, and a person of ordinary skill often will
be able to fit the teachings of multiple patents together like pieces of a
puzzle.") (Emphasis omitted).
A person of ordinary skill in the art would have recognized the
suitability of performing a method to formulate a semiconductor device such
as described by Khakifirooz wherein the STI region extends through and
abutting the sidewalls of the first oxide layer, the nitride layer and the
second oxide layer and extends at least partially into the semiconductor
substrate. Bourdelle discloses the STI region extends through dielectric
materials and into the semiconductor wafer. Consequently, a person of
ordinary skill in the art would have recognized that dielectric materials can
be separated by an STI region. Appellants have not directed us to evidence
that establishes the inclusion of STI regions in semiconductor devices was
previously unknown. To the contrary, all of the evidence cited in this appeal
record establishes that semiconductor devices comprising various STI region
arrangements were known to persons of ordinary skill in the art. (See
Khakifirooz, and Bourdelle ). As such, a person of ordinary skill in the art
would have reasonably expected that a method to formulate a semiconductor
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device could have been performed wherein the STI region extends through
and abutting the sidewalls of the first oxide layer, the nitride layer and the
second oxide layer and extends at least partially into the semiconductor
substrate as required by independent claim 1. "Obviousness does not require
absolute predictability of success ... all that is required is a reasonable
expectation of success." In re Kubin, 561 F.3d 1351, 1359--60 (Fed. Cir.
2009) (citing In re O 'Farrell, 853 F.2d 894, 903---04 (Fed. Cir. 1988)).
Consequently, after consideration of Appellant's arguments, we are
unpersuaded of error in the Examiner's determination of obviousness.
According! y, we affirm the 3 5 U.S. C. § 10 3 (a) rejections of claims 1,
3, 7-9, 11, 14--16, and 23-33 for the reasons given above and presented by
the Examiner.
DECISION
The Examiner's prior art rejections of claims 1, 3, 7-9, 11, 14--16, and
23-33 are affirmed.
TIME PERIOD
No time period for taking any subsequent action in connection with
this appeal may be extended under 3 7 C.F .R. § 1.13 6( a)( 1 ).
AFFIRMED
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