Taiwan Semiconductor Manufacturing Co., Ltd.

Patent Trials and Appeals Board

Jul 2, 2021

2020004531 (P.T.A.B. Jul. 2, 2021)

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.
14/497,920 09/26/2014 Chen-Hua YU 2007.0110DIV/1085.1442 1021
54657 7590 07/02/2021
DUANE MORRIS LLP (TSMC)
IP DEPARTMENT
750 B Street, Suite 2900
San Diego, CA 92101-4681
EXAMINER
CHEN, DAVID Z
ART UNIT PAPER NUMBER
2815
NOTIFICATION DATE DELIVERY MODE
07/02/2021 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):
IDocketing@duanemorris.com
ipdocket@duanemorris.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte CHEN-HUA YU, LIANG-GI YAO, and CHENG-TUNG LIN
Appeal 2020-004531
Application 14/497,920
Technology Center 2800
Before CATHERINE Q. TIMM, KAREN M. HASTINGS, and
N. WHITNEY. WILSON, Administrative Patent Judges.
HASTINGS, Administrative Patent Judge.
DECISION ON APPEAL
STATEMENT OF THE CASE
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1, 3–5, 7–9, and 24–30. See Final Act.
1. We have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM.

1 We use the term “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42. Appellant identifies the real party in interest as Taiwan
Semiconductor Manufacturing Co., Ltd. Appeal Br. 3.
Appeal 2020-004531
Application 14/497,920

2
CLAIMED SUBJECT MATTER
The claims are directed to methods for making a high-k metal gate
device with a dual work function. Claim 1, reproduced below, is illustrative
of the claimed subject matter:
1. A method for forming a semiconductor device comprising:
forming a high-k dielectric material over a surface of a
substrate:
forming a metal layer suitable for use as gate electrodes
for N-metal semiconductor devices, over the high-k dielectric
material, said metal layer comprising TaN;
converting portions of said metal layer to TaSiN, said
converting including forming a patterned removable layer
comprising polysilicon over said metal layer, said converting
further including adding Si to said metal layer using diffusion or
gas cluster ion beam (GCIB) implantation, wherein the converted
portions of TaSiN have a higher work function than the work
function of said metal layer prior to said converting; and
forming the N-metal semiconductor devices using
unconverted portions of said metal layer.

Independent claim 24 is similar to claim 1, but limits the addition of
Si to the metal layer to “using diffusion” (Claims Appendix 13–14).
REFERENCES
The prior art relied upon by the Examiner is:
Name Reference Date
Yu US 7,033,919 B1 Apr. 25, 2006
Clark US 2002/0173131 A1 Nov. 21, 2002
Ngai US 2002/0175384 A1 Nov. 28, 2002
Narayanan US 2005/0250318 A1 Nov. 10, 2005
Chidambaram US 2006/0199285 A1 Sept. 7, 2006

Appeal 2020-004531
Application 14/497,920

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REJECTION
Claims 1, 3–5, 7–9, and 24–30 are rejected under 35 U.S.C. § 112(a)
or 35 U.S.C. § 112 (pre-AIA), first paragraph, as failing to comply with the
enablement requirement. Final Act. 2–3.
OPINION
When rejecting a claim under the enablement requirement of section
112, the PTO bears an initial burden of setting forth a reasonable explanation
as to why it believes that the scope of protection provided by that claim is
not adequately enabled by the description of the invention provided in the
specification of the application; this includes, of course, providing sufficient
reasons for doubting any assertions in the Specification as to the scope of
enablement. If the PTO meets this burden, the burden then shifts to the
applicant to provide suitable proofs indicating that the specification is indeed
enabling. In re Marzocchi, 439 F.2d 220, 223–24 (CCPA 1971); In re
Wright, 999 F.2d 1557, 1561–62 (Fed. Cir. 1993).
While the Specification need not disclose what is well-known in the
art2, the knowledge of one skilled in the art cannot be relied upon to supply
information that is required to enable the novel aspect of the claimed
invention. Auto. Techs. Int’l Inc. v. BMW of N. Am., Inc., 501 F.3d 1274,

2 “The specification need not disclose what is well-known to those skilled in
the art and preferably omits that which is well-known to those skilled and
already available to the public.” MPEP § 2164.05(b) (9th ed. Rev. 10.2019,
rev. June 2020) citing In re Buchner, 929 F.2d 660, 661 (Fed. Cir. 1991);
Hybritech, Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1384 (Fed.
Cir. 1986); Lindemann Maschinenfabrik GMBH v. Am. Hoist & Derrick Co.,
730 F.2d 1452, 1463 (Fed. Cir. 1984).

Appeal 2020-004531
Application 14/497,920

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1283 (Fed. Cir. 2007); ALZA Corp. v. Andrx Pharms., LLC, 603 F.3d 935,
941 (Fed. Cir. 2010).
The Examiner provides adequate reasons for doubting whether
Appellant’s disclosure enables the “converting portions of said metal layer
[of TaN] to TaSiN” so as to have a higher work function than the work
function of said metal layer prior to said converting over the scope of claim
1 (Appeal Br. 9–10). The Examiner points out that Yu teaches adding (e.g.,
implanting) silicon into NMOS metal which effectively achieves a lower
work function than that of PMOS metal as it is desirable to have a lower
work function in N-metal (Ans. 8–9; Final Act. 3–4). Even further, the
Examiner points out that Ngai teaches increasing the amount of silicon in
TaSiN will decrease the work function of the material (Final Act. 7–9; e.g.,
see Ngai ¶¶ 12–14). Therefore, both Yu and Ngai provide sufficient
evidence that adding silicon to a material may decrease the work function of
the material, rather than increase it, as claimed.
Appellant argues that Pan’s3 Figure 10 and Wen’s4 Figure 4.16(b)
provides teachings which would enable the conversion of TaN to TaSiN in
order to increase the work function of the material (Appeal Br. 10;

3 James Pan et al., Metal Gate NMOSFETS with TaSiN/TaN Stacked
Electrode Fabrication By A Replacement (Damascene) Technique, 2003
International Symposium on VLSI Technology, Systems, and Applications,
Proceedings.
4 Huang-Chun Wen, Systematic Evaluation of Metal Gate Electrode
Effective Work Function and its Influence on Device Performance in CMOS
Devices, The University of Texas at Austin (2006).
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Declarations5). We are unpersuaded because a preponderance of the
evidence indicates that the relationship between TaSiN and work function is
more complicated than argued by Appellant. Wen’s Figure 4.16(b) illustrates
a prior art teaching of how the work function of TaN changes when different
percentages of silicon are added (see e.g., Hsu Decl. 13). Appellant does not
dispute the Examiner’s finding that Wen’s Figure 4.16(b) actually shows a
decreasing work function of TaSiN versus TaN for percentages of added
silicon above about 35% – a result opposite of that recited in claim 1 (Ans.
8; no responsive brief has been filed). Appellant also does not dispute the
Examiner’s finding that the method used for adding Si in Wen of PVD
(plasma vapor deposition) is different than an implantation method as
claimed herein and used in Yu (e.g., Ans. 5). Thus, it appears that while
using a PVD method may achieve an increased work function, Yu’s method
achieves a completely opposite decreased work function (id.). Appellant
also does not sufficiently dispute the Examiner’s finding that the use of an
appropriate “high-k gate dielectric material” appears to be critical for
achieving the increased work function claimed herein (Ans. 5). A
preponderance of the evidence indicates that work function depends on
various parameters, which must be varied to determine whether the work
function increases or decreases.
The Examiner points out that none of the “critical controlling
parameters,” (such as the percentage of added silicon up to about 35% or use
of an appropriate gate material), are described in the disclosure in a way that

5 First Declaration of Liang-Gi Yao, dated July 30, 2015 (First Yao Decl.);
Second Declaration of Liang-Gi Yao, dated June 2, 2016 (Second Yao
Decl.); Declaration of Chin-You Hsu, dated January 19, 2017 (Hsu Decl.).
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Application 14/497,920

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would enable one of ordinary skill in the art to carry out the claimed
converting step and arrive at a higher work function for TaSiN (Ans. 8).
Thus, the Examiner concludes that the scope of claim 1 is not enabled by the
disclosure because the exemplary embodiments in Appellant’s disclosure
appear to be missing one or more “critical controlling parameters” (Ans. 8;
see also Ans. 3 (discussing e.g., Spec. ¶¶ 14, 16) that would enable one of
ordinary skill in the art to convert a material by adding silicon to increase the
work function (Ans. 3–5, 7–9).
While the Specification generally need not disclose what is well-
known in the art, the knowledge of one skilled in the art cannot be relied
upon to supply information that is required to enable the novel aspect of the
claimed invention (controlling parameters such as amount, degree, or
percentage of e.g., silicon needed in order to convert TaN to a TaSiN metal
with a higher work function). Auto. Techs. Int’l, 501 F.3d at 1283
(“Although the knowledge of one skilled in the art is indeed relevant, the
novel aspect of an invention must be enabled in the patent.”); ALZA Corp.,
603 F.3d at 941. In other words, “[i]t is the specification, not the knowledge
of one skilled in the art, that must supply the novel aspects of an invention in
order to constitute adequate enablement.” Genentech, Inc. v. Novo Nordisk,
A/S, 108 F.3d 1361, 1366 (Fed. Cir. 1997).
Therefore, for all the reasons above and detailed in the Examiner’s
Answer, Appellant has not shown error in the Examiner’s rejection that the
Specification is not enabling for the claimed invention, since Appellant’s
proffered evidence concerns the novel aspect of the claimed invention. As
discussed above, knowledge of one skilled in the art cannot be relied upon to
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supply information that is required to enable the novel aspect of the claimed
invention.
Accordingly, we sustain the § 112 rejection of all of the claims on
appeal.
CONCLUSION
The Examiner’s rejection is AFFIRMED.

DECISION SUMMARY
Claim(s)
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1, 3–5, 7–9,
24–30
112 Enablement 1, 3–5, 7–9,
24–30

TIME PERIOD FOR RESPONSE
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R.
§ 1.136(a)(1)(iv).
AFFIRMED