Huang Liu et al.

Patent Trials and Appeals Board

Jul 21, 2020

2018001645 (P.T.A.B. Jul. 21, 2020)

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.
14/219,039 03/19/2014 Huang Liu EU552/4014.252100 1764
123187 7590 07/21/2020
Williams Morgan, P.C.
6464 Savoy
Suite 600
Houston, TX 77036
EXAMINER
MAI, ANH D
ART UNIT PAPER NUMBER
2829
NOTIFICATION DATE DELIVERY MODE
07/21/2020 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@wmalaw.com
nnolan@wmalaw.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte HUANG LIU, WEN-PIN PENG, and JEAN-BAPTISTE LALOE 1
____________

Appeal 2018-001645
Application 14/219,039
Technology Center 2800
____________

Before ROMULO H. DELMENDO, JAMES T. MOORE, and
MONTÉ T. SQUIRE, Administrative Patent Judges.

DELMENDO, Administrative Patent Judge.

DECISION ON APPEAL
The Appellant files this appeal under 35 U.S.C. § 134(a) from a final
rejection of claims 1–3 and 5–7.2 We have jurisdiction under 35 U.S.C.
§ 6(b).
We REVERSE.

1 We use the word “Appellant” to refer to “applicant” as defined in 37
C.F.R. § 1.42—“GLOBALFOUNDRIES Inc.,” Application Data Sheet filed
March 19, 2014 at 4, which is also listed as the real party in interest. Appeal
Brief dated June 5, 2017 (“Appeal Br.”) 2.
2 Claims 4 and 10–20 are withdrawn. Appeal Br. 15–18 (Claims App.).
Claims 8 and 9 were cancelled after final rejection. Id.; Advisory Action
entered February 9, 2017; Amendment filed February 9, 2017.
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Application 14/219,039

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BACKGROUND
The Appellant’s claims are directed to a method for forming a metal
gate on a semiconductor device including de-oxidizing the metal gate using
a reducing agent. Specification filed February 18, 2016 (“Spec.”) ¶ 14. The
Specification discloses that the process of fabricating semiconductor devices
in an open-air environment may oxidize exposed portions of metal gates
previously formed on the devices. Id. ¶ 2. According to the Specification,
This oxidation can alter the characteristics of the gate metal, and,
by extension, the gate itself, causing the gate to perform less
optimally. In addition, the presence of an oxide layer can lead to
unintended consequences in later fabrication steps, further
degrading the performance of the gate.
Id. To solve this problem, the Specification discloses that “[a] reducing
agent can be used to de-oxidize the metal that forms the metal gate, leaving a
substantially non-oxidized surface.” Id. ¶ 14.
Claim 1, the sole independent claim on appeal, is representative of the
subject matter on appeal and is reproduced below:
1. A method for forming a metal gate in a
semiconductor device, comprising:
forming the metal gate on a substrate in the semiconductor
device;
de-oxidizing, using a reducing agent, an oxidation layer
formed on the metal gate; and[]
forming raised source-drains in proximity to the metal
gate.
Appeal Br. 15 (Claims App.).
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REJECTIONS ON APPEAL3
1. The Examiner rejected claims 1, 2, and 5–7 under 35 U.S.C.
§ 103 as unpatentable over the combination of Chiang4 and Wood.5 Final
Office Action entered November 7, 2016 (“Final Act.”) 5–7; Examiner’s
Answer entered October 3, 2017 (“Ans.”) at 5–13.
2. The Examiner rejected claim 3 under 35 U.S.C. § 103 as
unpatentable over the combination of Chiang, Wood, and Ngo.6 Final Act.
7; Ans. 13.
3. The Examiner rejected claims 1–3, 5, and 7 under 35 U.S.C.
§ 103 as unpatentable over the combination of Chiang and Ngo. Final Act.
8–9; Ans. 13–14.
4. The Examiner rejected claim 6 under 35 U.S.C. § 103 as
unpatentable over the combination Chiang, Ngo, and Chang.7 Final
Act. 9–10; Ans. 14–15.

3 The rejections of claim 8 under 35 U.S.C. § 112(b) as being indefinite and
claims 8 and 9 under 35 U.S.C. § 112(d) as being improper dependent
claims, as set forth in the Final Action, are moot because claims 8 and 9
have been cancelled.
4 Chiang et al., US 2013/0113027 A1, published May 9, 2013.
5 Wood et al., US 7,604,708 B2, issued October 20, 2009.
6 Ngo et al., US 6,335,283 B1, issued January 1, 2002.
7 Chang et al., US 8,202,776 B2, issued June 19, 2012.
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DISCUSSION
I. Obviousness of Claims 1–3 and 5–7 over the Combination of Chiang,
Wood, and Ngo (for Claim 3)
The Examiner finds that Chiang teaches “a method forming a metal
gate in a semiconductor device” including the steps of “forming the metal
gate (330) on . . . substrate (300) in the semiconductor device; forming . . .
oxidation layer (335) on . . . metal gate (330); and forming raised source-
drains [sic] [electrodes] (322) in proximity to . . . metal gate (330).” Final
Act. 5 (citing Chiang, Figs. 5–6); see also id. ¶¶ 21–22. The Examiner
acknowledges that Chiang does not explicitly disclose de-oxidizing the
oxidation layer formed on the metal gate. Id. Nevertheless, the Examiner
finds that the “metal oxide layer 335, above . . . metal gate 330, must be
removed so that electrical contact can be made to the gate.” Ans. 4.
The Examiner finds that “Wood teaches a method for forming a
contact to a metal in a semiconductor device including: de-oxidizing, using a
reducing agent, . . . oxidation layer (12) formed on . . . metal (16).” Id. The
Examiner finds that Wood teaches “the de-oxidizing agent interacts more
specifically with . . . deposits 12 and [does] not undesirably damage the
structure of . . . surrounding low k dielectric layer 18.” Id. at 13 (citing
Wood 5:9–26). The Examiner therefore concludes that
it would have been obvious to one having ordinary skill in the art
at the time of invention was made to form [the] metal gate of
Chiang[,] including de-oxidizing the oxidation layer formed on
the metal gate as taught by Wood[,] to remove the oxidation layer
without damaging the surrounding layers.
Id. at 6.
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The Appellant argues that the Examiner “fails to identify the reason
why the person of ordinary skill in the art would have combined the prior art
references in the manner set forth in the claims.” Appeal Br. 5.
Specifically, the Appellant contends that “no evidence of record supports the
contention that the person of ordinary skill in the art would wish to remove
Chiang’s protective layer 335 by any technique.” Id. Rather, the Appellant
contends that Chiang teaches forming protective oxidation layer 335 by
performing an oxygen treatment as a preferred embodiment. Id. (citing
Chiang ¶ 22). What is more, the Appellant points out that Chiang discloses
forming dielectric layer 329 and barrier layer 336 over oxidation layer 335.
Id. at 6. (citing Chiang ¶¶ 25–26; Figs. 8, 10). Based on these disclosures,
Appellant contends that Chiang suggests retaining, rather than removing,
oxidation layer 335. See id. at 5–6.
Additionally, the Appellant argues that a person of ordinary skill in
the art would not have been motivated by Wood to modify Chiang. See id.
at 8–9. The Appellant argues that Wood teaches “that oxides are undesirable
on metal-containing conductors deposited on a substrate.” Id. at 8 (citing
Wood 1:13–2:38). The Appellant contends that, therefore, Wood’s teaching
is not relevant to Chiang’s gates or transistors. Id. (citing Chiang ¶¶ 25–26).
We agree with the Appellant and find that a preponderance of the
evidence does not support the Examiner’s rejection. In a preferred
embodiment, Chiang teaches intentionally performing an oxygen treatment
on the low resistance layer of the metal gate to form an oxidized protective
layer 335. Chiang ¶ 22. Chiang teaches that this oxidized protective layer
335 prevents transistor 340 from being damaged due to etching selectivity.
Id. ¶ 26. Thus, although described in the context of a preferred embodiment
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of Chiang’s gate structure, Wood’s teachings regarding a de-oxidation
process to remove an undesired oxide film 12 from a surface 14 of a
conductor 16, Wood 1:14–47; 4:45–50, are inapt for Chiang’s gate in which
an oxide film is disclosed as a protective film, not an undesired deposited
film. “The mere fact that the prior art may be modified in the manner
suggested by the Examiner does not make the modification obvious unless
the prior art suggested the desirability of the modification.” In re Fritch,
972 F.2d 1260, 1266 (Fed. Cir. 1992). Accordingly, we reverse the rejection
of claim 1 under 35 U.S.C. § 103 over the combination of Chiang and
Wood. The rejections of dependent claims 2, 3, and 5–7 over Chiang,
Wood, and Ngo (for claim 3) fall with claim 1.

II. Obviousness of Claims 1–3 and 5–7 over the Combination of Chiang,
Ngo and Chang (for Claim 6)
The Examiner finds that “Ngo teaches a method for forming a contact
to a metal in a semiconductor device including: de-oxidizing, using a
reducing agent, . . . oxidation layer (24) formed on . . . metal (23).” Final
Act. 8 (citing Ngo, Figs. 2–4); see also Ngo 6:20–56. The Examiner
concludes that “it would have been obvious to one having ordinary skill in
the art at the time of invention was made to form [the] metal gate of Chiang
including de-oxidizing the oxidation layer formed on the metal gate as
taught by Ngo to clean the exposed surface of the metal.” Id.
The Appellant contends that “[l]ike Wood, Ngo is directed to cleaning
oxides from conductive lines[,] such as copper oxide film 24 from copper
lines 23. Ngo is silent regarding metal gates.” Appeal Br. 11 (emphasis
omitted). Hence, Appellant argues that a person of ordinary skill in the art
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would not have been motivated by Ngo “to remove Chiang’s protective layer
335 from metal gate 330.” Id. at 12 (emphasis omitted).
We agree with the Appellant and find that the preponderance of the
evidence does not support the Examiner’s rejection. As in the rejection
based on Wood, Ngo has not been shown to provide a reason for removing
Chiang’s protective layer by de-oxidizing using a reducing agent because
such a removal is inconsistent with Chiang’s stated goal and, additionally,
Ngo is directed to conductive lines and not gates. Accordingly, we reverse
the rejection of claim 1 under 35 U.S.C. § 103 over the combination of
Chiang and Ngo. The rejections of dependent claims 2, 3, and 5–7 over
Chiang, Ngo, and Chang (for claim 6) fall with claim 1.
CONCLUSION
In summary, we reverse the Examiner’s rejections under 35 U.S.C.
§ 103 as follows:
Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1, 2, 5–7 103 Chiang, Wood 1, 2, 5–7
3 103 Chiang, Wood, Ngo 3
1–3, 5, 7 103 Chiang, Ngo 1–3, 5, 7
6 103 Chiang, Ngo, Chang 6
Overall
Outcome
1–3, 5–7

REVERSED