Ex Parte Wann et al

Patent Trials and Appeals Board

Feb 28, 2019

13729806 - (D) (P.T.A.B. Feb. 28, 2019)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
13/729,806 12/28/2012
43859 7590 03/04/2019
SLATER MATSIL, LLP/TSMC
17950 PRESTON ROAD, SUITE 1000
DALLAS, TX 75252
FIRST NAMED INVENTOR
Clement Hsingjen Wann
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.
TSM12-1059 7826
EXAMINER
YECHURI, SITARAMARAO S
ART UNIT PAPER NUMBER
2818
NOTIFICATION DATE DELIVERY MODE
03/04/2019 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):
docketing@slatermatsil.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte CLEMENT HSINGJEN WANN, CHIH-HSIN KO,
CHENG-HSIEN WU, DING-KANG SHIH, and
HAU-YU LIN
Appeal2017-004436
Application 13/729,806
Technology Center 2800
Before ROMULO H. DELMENDO, WESLEY B. DERRICK, and
MICHAEL G. McMANUS, Administrative Patent Judges.
DERRICK, Administrative Patent Judge.
DECISION ON APPEAL
1
STATEMENT OF THE CASE
Appellant2 seeks review under 35 U.S.C. § 134 from the maintained
rejection under 35 U.S.C. § 103 of claims 14, 15, 17-22, 27-30, 33, and 34
1 We refer to the Specification filed December 28, 2012 ("Spec."), the Final
Office Action dated October 29, 2015 ("Final Act."), the Appeal Brief filed
May 13, 2016 ("App. Br."), the Examiner's Answer dated November 18,
2016 ("Ans."), and the Reply Brief filed January 18, 2017 ("Reply Br.").
2 Appellant is the Applicant, Taiwan Semiconductor Manufacturing
Company, Ltd., which, according to the Appeal Brief, is the real party in
interest. App. Br. 3.
Appeal2017-004436
Application 13/729,806
overKim3 in viewofMukherjee4 and Tanioku, 5 of claims 35-37 over Kim
in view of Mukherjee, Tanioku, and Lai, 6 and of claims 16, 23, 24, 31, and
32 over Kim in view of Mukherjee, Tanioku, and Vaquila. 7' 8 We have
jurisdiction under 35 U.S.C. § 6.
We REVERSE.
THE INVENTION
The subject matter of the claims on appeal relates to a complimentary
metal-oxide-semiconductor (CMOS) device and a method of forming the
same. Spec., Abstract. Independent claims 14, 21, and 29 are directed to
methods of forming an integrated circuit.
Claim 14, reproduced with added emphasis, is representative:
14. A method of forming an integrated circuit, comprising:
forming a first source/drain region in a p-type region and
a second source/drain region in an n-type region;
forming a dielectric over the n-type region and the p-type
reg10n;
etching trenches in the dielectric over the first
source/drain region and the second source/drain region;
depositing titanium in the trenches; and
3 Kim et al., US 2010/0123198 Al, published May 20, 2010.
4 Mukherjee et al., US 2010/0155846 Al, published June 24, 2010.
5 Tanioku, US 2010/0255652 Al, published October 7, 2010.
6 Lai & Chen, J., Effects of composition on the formation temperatures and
electrical resistivies of C54 titanium germanosilicide in Ti-Si 1-x Ge x
systems, APPLIED PHYS. 86 (3), 1340-45 (1991).
7 Vaquila et al., Oxidation process in titanium thin films, PHYSICAL REv. B
55 (20), 13 925-931 (1997).
8 Prior pending rejections under 35 U.S.C. § 112 have been withdrawn.
Ans. 2; Final Act. 2-5.
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Application 13/729,806
while the titanium in the trenches over the first
source/drain region and the second source/drain region is
exposed, peiforming an annealing process to form titanium
dioxide (Ti02) over the first source/drain region and to
generate a titanium-containing region in the second
source/drain region, the titanium-containing region comprising
a titanium-semiconductor compound.
App. Br. (Claims Appendix), 23. Independent claim 21 similarly recites an
annealing step that "simultaneously form[ s] a first titanium-containing
material ... compris[ing] titanium dioxide" and "a second titanium-
containing material ... compris[ing] one of titanium silicon germanium and
titanium digermanium." Id. at 24--25. Independent claim 29 similarly
requires depositing a titanium layer on the surfaces of a first and second
epitaxial material and simultaneously forming a first titanium-containing
material formed from a titanium layer that is a dielectric material and a
second titanium-containing material formed from a titanium layer and
epitaxial material that is a conductive material, wherein "the first titanium-
containing material being [sic] does not contain the first epitaxial material."
Id. at 25-26.
DISCUSSION
On this record, having reviewed the grounds set forth by the
Examiner, Appellant's arguments, and the Examiner's response, we are
persuaded that the Examiner has failed to establish that the claims are
unpatentable.
For any ground of rejection, "the [E]xaminer bears the initial burden
... of presenting aprimafacie case ofunpatentability." In re Oetiker, 977
F.2d 1443, 1445 (Fed. Cir. 1992).
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Application 13/729,806
As to independent claim 14, the Examiner relies on Kim for
disclosing a method of forming an integrated circuit, particularly, in
referring to Kim Figure IE, the steps of: (i) forming a first source/drain
region in a p-type region-the right side is NMOS-and a second
source/drain region in an-type region-left side is PMOS, (ii) forming a
dielectric 60 over the n-type region and the p-type region, (iii) etching
trenches HB and HA in the dielectric over the first source/drain region and
the second source/drain region, (iv) depositing a barrier metal layer 70 in the
trenches, which can be titanium, and (v) performing an annealing step to
form a titanium-containing region in the source/drain regions adjacent to the
titanium barrier layer, particularly silicide films 80A and 80B. Final Act. 9
(citing Kim ,r,r 34--51, Fig. IE); see also id. at 13 & 16 (addressing
independent claims 21 and 29, respectively).
Kim discloses that the silicide films 80A and 80B contact the contact
plugs 90 formed in the trenches following the annealing step and that these
metal silicide films "may reduce the height of Schottky barriers in contact
regions and thus reduce sheet resistance." Kim ,r 50. Kim further discloses
that different metal silicides have different work functions, some high, and
some low. Id. ,r,r 7-8.
The Examiner concedes that Kim does not teach titanium dioxide
(Ti02) over the first source/drain region. Final Act. 9.
The Examiner turns to Mukherjee, which teaches metal-insulator-
semiconductor tunneling contacts, for disclosing that "the inclusion of an
insulating layer 114 between the conducting layer 116 and the source or
drain region 106, 108 may actually reduce the resistance of the contact over
a situation where a conductor is in direct contact with the source or drain
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Application 13/729,806
region 106, 108" and highlights "embodiments with a thermally-grown
insulating layer 114" (emphasis omitted). Id. at 10 (citing Mukherjee ,r,r 24,
29, Fig. 1). The Examiner further relies on Mukherjee for disclosing that
"[ t ]he insulating layer 114 may comprise a dielectric material such as Hf02,
AlO, ZrO, ShN4, Si02, SiON, or another insulating dielectric material"
(emphasis omitted) (Ans. 2 (quoting Mukherjee ,r 29)) and reasons that the
particular "materials cited by Mukherjee are merely examples, and the
teaching of Mukherjee is that any insulating dielectric can be used" (id.).
Mukherjee also discloses that "[t]his type of contact may ... allow the
tuning of the Schottky barrier height and contact as desired for optimal ...
performance" of its device. Mukherjee ,r 24.
The Examiner concludes that "it would have been obvious to use
titanium dioxide (Ti02) [sic] over source/drain region(s) of either NMOS or
PMOS or both and the motivation is to obtain depinning the metal Fermi
level giving ease of design and/or better contact, easier to make." Final Act.
10. As to forming the Ti02 film, the Examiner relies on Tanioku as teaching
that annealing a titanium film at 400Q C in the presence of oxygen provides a
Ti02 film. Final Act. 10 (citing Tanioku ,r,r 13-22, 38-51, 56-58, 93-94);
see also Ans. 3 (maintaining that annealing the titanium layer in the presence
of oxygen would certainly result in titanium dioxide).
As to the "titanium-semiconductor compound," the Examiner relies
on a metal silicide layer (or titanium silicon germanium layer) formed upon
annealing. Final Act. 10-11 (citing the silicide films 80A and 80B of Kim).
The Examiner maintains that its formation is inherent upon the annealing
used to form the titanium dioxide layer. Id.; Ans. 4--5. Specifically, the
Examiner maintains that in the combination of Kim, Mukherjee, and
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Tanioku to obtain the titanium dioxide layer, the titanium will also react with
the semiconductor material during the step to oxidize the titanium. Id.
The Examiner's reasoning shifts in the Answer in that "the Titanium
layer is now used to form the titanium dioxide layer and the formation of the
silicides is inherent due to the temperature used in the anneal." Ans. 4.
As to independent claims 21 and 29, the Examiner likewise relies on
the titanium dioxide as the recited "first titanium-containing material
compris[ing] titanium dioxide" ( claim 21) and the "first titanium-containing
material ... [ that is] a dielectric material" ( claim 29) and on the concomitant
products of titanium with the semiconductor as "the second titanium-
containing material compris[ing] one of titanium silicon germanium and
titanium digermanium" ( claim 21) and "the second titanium-containing
material ... [that is] conductive material" (claim 29). Final Act. 13-14, 16-
18.
Appellant argues that the Examiner has failed to establish that it
would have been obvious to include a titanium dioxide layer. App. Br. 15-
1 7; Reply Br. 6-7. The Examiner relies on including a titanium dioxide
layer in each ground of rejection. See generally Final Act.; Ans. Appellant
also argues that including a titanium dioxide layer over Kim's silicide films
80A and 80B would alter its device such that the films 80A and 80B would
have no function, negating any motivation to form them. App. Br. 18.
Appellant's arguments highlight how the Examiner's grounds of rejection
fall short of establishing that the claims are unpatentable for obviousness.
While Kim details that different silicide films have different work
functions, the basis for including titanium as the barrier layer that reacts with
semiconductor material during annealing to form metal silicide ( or
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germanium) was simply that it was an example of a metal that could be used.
Final Act. 9; Kim ,r 4 7. The degree to which using titanium as the barrier
metal would, upon forming a particular film 80A and/or 80B, lower the
device's contact resistance is not squarely addressed by the Examiner. See
generally Final Act.; Ans. Absent such, the Examiner's rationale to modify
Kim by annealing in the presence of oxygen to provide a titanium dioxide
layer lacks a sufficient rational basis because it is not manifest that doing so
would provide any benefit, particularly where the function of Kim's films
80A and 80B would be lost. See, e.g., App. Br. 18; Reply Br. 8-9.
The shift in the purpose of the titanium layer from forming silicide
films 80A and 80B of Kim (Final Act. 10) to forming the titanium dioxide
layer, with the formation of the silicides being inherent to the temperature
used in the anneal (Ans. 4), renders the rejection untenable. As originally
set forth, the reason for using titanium was in order to obtain the benefits of
the silicide films 80A and 80BA. Final Act. 9 (citing Kim ,r,r 47, 49). With
the shift in reasoning, on this record, there is no longer any particular reason
to use the metals identified in Kim, including titanium.
The Examiner's reliance on Mukherjee also falls short of providing a
sufficient basis for using titanium dioxide in Kim's device. Mukherjee
discloses use of insulating dielectric material, including, as examples,
particular metal oxides, but it does not identify titanium dioxide in
particular. Mukherjee ,r 29. Kim does identify titanium metal, as well as
other metals and alloys thereof, for use in its barrier metal layer 70 (Kim
,r 47), but this use is in light of the silicide films 80A and 80B being formed
between the barrier metal layers 70 and exposed SiGe and Si epitaxial layers
(id. ,r 48). The Examiner fails to sufficiently explain how titanium dioxide
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formed from a barrier titanium layer in Kim's device upon annealing in the
presence of oxygen would reasonably be expected to function in the manner
of Mukherjee's insulating layer, particularly where the structure in
Mukherjee, as highlighted by Appellant, is not merely functioning as
insulation, but reduces resistance. See Reply Br. 7, 8-9; Mukherjee ,r 24.
Further, even if all that is required is that the material be an insulating
dielectric material, titanium dioxide would be merely one of any number of
insulating dielectric materials that could be used, and this is not sufficient to
support the Examiner's rejection. "[O]bviousness concerns whether a
skilled artisan not only could have made but would have been motivated to
make the combinations or modifications of prior art to arrive at the claimed
invention." Belden v. Berk-Tek LLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015).
For these reasons, we are unable to sustain the rejections of each of
independent claims 14, 21, and 29.
The Examiner's further reliance on Lai as to dependent claims 35-37
(Final Act. 15-16) and Tanioku as to dependent claims 16, 23, 24, 31, and
32 (id. at 18-19) does not remedy the deficiencies in the rejection of the
base, independent claims.
Accordingly, we do not sustain the Examiner's obviousness
rejections.
DECISION
The Examiner's decision rejecting claims 14--24 and 27-37 is
REVERSED.
REVERSED
8