Yasuyuki Hoshi et al.

Patent Trials and Appeals Board

Sep 1, 2020

2019000114 (P.T.A.B. Sep. 1, 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.
15/250,005 08/29/2016 Yasuyuki HOSHI ASA-135 1087
23995 7590 09/01/2020
Rabin & Berdo, PC
2650 Park Tower Drive
Suite 800
Vienna, VA 22180
EXAMINER
YEMELYANOV, DMITRIY
ART UNIT PAPER NUMBER
2891
NOTIFICATION DATE DELIVERY MODE
09/01/2020 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):
eofficeaction@appcoll.com
firm@rabinberdo.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte YASUYUKI HOSHI, YUICHI HARADA, and TAKASHI SHIIGI
____________

Appeal 2019-000114
Application 15/250,005
Technology Center 2800
____________

Before JEFFREY B. ROBERTSON, JEFFREY R. SNAY, and
MICHAEL G. MCMANUS, Administrative Patent Judges.

SNAY, 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 rejecting claims 1, 3, and 5–12. We have jurisdiction
under 35 U.S.C. § 6(b).
We AFFIRM-IN-PART.

1 We use the word Appellant to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. Appellant identifies the Fuji Electric Co., Ltd. as the real party in
interest. Appeal Brief, February 26, 2018, 3.
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BACKGROUND
The invention relates to a semiconductor device and its method of
manufacture. Spec. 1. Claims 1 reads as follows:
1. A semiconductor device, comprising:
a substrate formed of a wide-band-gap semiconductor
material that has a band gap greater than that of silicon, the
substrate having a front surface and a back surface;
a deposit layer formed of the wide-band-gap
semiconductor material and having an impurity concentration
lower than that of the substrate, the deposit layer having a first
side and a second side opposite to the first side, and being
deposited on the front surface of the substrate that is located on
the second side;
a semiconductor region selectively disposed in the
deposit layer on the first side thereof;
a semiconductor layer formed of the wide-band-gap
semiconductor material, disposed on a surface of the deposit
layer on the first side and a surface of the semiconductor region
formed in the deposit layer, the semiconductor layer having
selectively disposed therein a first region, a second region and a
contact region;
a gate electrode disposed, via a gate insulating film, on
the semiconductor layer and the first region;
an interlayer insulating film covering the gate electrode;
a source electrode in contact with the contact region and
the second region;
a drain electrode disposed on the back surface of the
substrate;
a plating film selectively disposed on the source
electrode; and
a pin electrode in contact with the plating film, wherein
the substrate, the deposit layer, and the first and second
regions formed in the semiconductor layer are of a first
conductivity type,
the semiconductor region, the semiconductor layer and
the contact region formed therein are of a second conductivity
type,
the source electrode has a first titanium nitride (TiN)
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film, and a first titanium (Ti) film, a second TiN film, a second
Ti film, and a metal film containing aluminum (Al) sequentially
formed on the first TiN film, and
the first TiN film is formed on, and in direct contact with,
the interlayer insulating film.
Appeal Br.2 15–16 (Claims Appendix) (emphasis added to highlight a key
recitation in dispute). Claim 7 recites a method for making a device
essentially as recited in claim 1. Claim 12 is similar to claim 1 and requires
a second protective film that is a polyamide. Each remaining claim on
appeal depends from claim 1 or 7.

REJECTIONS
I. Claims 1, 3, and 5–9 stand rejected under 35 U.S.C. § 103 as
unpatentable over Applicant’s Admission of Prior Art (“AAPA”)3 and
Moon.4
II. Claims 10 and 11 stand rejected under 35 U.S.C. § 103 as
unpatentable over AAPA, Moon, and Wanlass.5
III. Claim 12 stands rejected under 35 U.S.C. § 103(a) as unpatentable
over AAPA and Merchant.6

2 Appellant’s Claims Appendix and arguments are found in Appellant’s
Supplemental Appeal Brief, filed April 4, 2018, which we cite as “Appeal
Br.” in this Decision.
3 The Examiner relies on Figure 3 of the Specification as Admitted Prior Art.
Final Act. 2–3.
4 US 2006/0183327 A1, published August 17, 2006.
5 US 6,069,047, issued May 30, 2000.
6 US 6,410,986 B1, issued June 25, 2002.
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OPINION
Rejection I: obviousness over AAPA and Moon
With regard to Rejection I, Appellant argues only claim 1. See
Appeal Br. 7–14. We focus our remarks on Appellant’s arguments
concerning claim 1. Claims 3 and 5–9 stand or fall with claim 1.
Claim 1 requires, inter alia, a source electrode having a first TiN film
formed on and in direct contact with an interlayer insulating film, and a first
Ti film, second TiN film, second Ti film, and Al-containing metal film
sequentially formed on the first TiN film. The Examiner finds AAPA
includes all of the features recited in claim 1 except the above-noted source
electrode structure. Final Act. 2–4. Rather, AAPA provides a source
electrode having “a two-layer structure of a first Ti film 21 and an Al–Si
film 24.” Spec. 4. The Examiner further finds that Moon teaches a source
electrode having barrier layers in the form of a TiN/Ti/TiN/Ti layered
structure which advantageously provides increased oxidation resistance.
Final Act. 4 (citing Moon ¶¶ 31, 46).
Appellant argues Moon’s disclosed increase in oxidation resistance
requires a nitrogen rich region formed at the top surface of the barrier layer,
and that the presence of such a nitrogen rich region would fail to meet the
source electrode structure recited in claim 1. Appeal Br. 7–9; Reply Br. 3.
Appellant also argues that removing Moon’s nitrogen-rich regions would
change the principle of operation of the barrier layers and would render them
unsatisfactory for their intended purpose. Appeal Br. 12–14.
Appellant’s arguments are not persuasive of reversible error. Moon
expressly teaches using TiN/Ti/TiN/Ti barrier layer stacks to provide
increased oxidation resistance. Moon ¶ 46 (“Barrier layer stacks comprising
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. . . TiN/Ti/TiN/Ti . . . may be formed. A multi-layer stack of barrier layers
provides increased oxidation resistance.”). Appellant correctly notes that
Moon further discloses providing nitrogen-rich regions. Moon teaches
forming such regions through nitridation of deposited Ti or TiN layers. See
e.g. Moon ¶ 28 (“[T]he top surface of the barrier layer 106 is exposed to a
nitridation treatment 108, as shown in Fig. 2 in a cross-sectional view, to
form a barrier layer 106’ having a nitrogen rich region 110 disposed at a top
surface thereof.”). See also id. ¶ 46 (“[A] plurality of barrier layers may be
deposited and exposed to the nitridation treatment . . . to form a multi-stack
of enhanced barrier layers.”). Thus, Moon teaches sequentially formed
TiN/Ti/TiN/Ti layers that are subjected to nitridation. Appellant does not
point to, and we do not see, language in claim 1 that would preclude Moon’s
nitridation step, or that would require any of the recited Ti or TiN layers to
be free of nitrogen-rich regions.
Appellant also argues Moon teaches use of barrier layers to prevent
copper diffusion, whereas AAPA does not disclose copper as a material
component of the semiconductor device. Appeal Br. 9–12; Reply Br. 5.
This argument also is not persuasive. AAPA includes “a metal film
containing aluminum” as a source electrode material. Spec. 6. Moon
teaches copper provides certain advantages relative to aluminum in
integrated circuits, including “decreased resistivity, resulting in increased
speed, decreased RC time delay, and the ability to form thinner conductive
lines.” Moon ¶ 4. As such, Moon provides a reason to include copper in the
semiconductor device of AAPA. See also, id. ¶ 31 (“The conductive
material 112 may comprise copper, aluminum, tungsten, or combinations or
alloys thereof.”). Moreover, Appellant’s argument neither refutes nor
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addresses the Examiner’s stated reason for adopting Moon’s barrier layers in
AAPA—namely, increased oxidation resistance. See id. ¶ 11 (“The novel
barrier layers described herein have improved copper diffusion barrier
properties and increased oxidation resistance.”) (emphasis added).
For the foregoing reasons, Rejection I is sustained.

Rejection II: obviousness over AAPA, Moon, and Wanlass
Appellant does not separately argue Rejection II except to rely on the
arguments presented in connection with claim 1. Appeal Br. 14. We sustain
Rejection II for the reasons set forth above regarding claim 1.

Rejection III: obviousness over AAPA and Merchant
With regard to the Examiner’s rejection of claim 12, Appellant argues
the Examiner erred in finding AAPA includes a second protective film that
is polyamide. Appeal Br. 14. We agree.
Claim 12 requires a polyamide second protective film. The Examiner
finds AAPA includes a “second protective film (17) [which] is a polyamide
film.” Final Act. 10. In support of that finding, the Examiner solely relies
on the fact that the Specification identifies reference numeral 17 in Figure 2
as a polyamide film. Ans. 9. However, as Appellant correctly observes,
Figure 2 in the Specification corresponds to an embodiment of the invention,
not admitted prior art. See, e.g., Spec. 7. The Examiner does not identify
evidence sufficient to support a finding that reference numeral 17 in Figure
3, which corresponds to AAPA, is a polyamide film.
For the foregoing reason, we do not sustain Rejection III.

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CONCLUSION
The Examiner’s decision rejecting claims 1, 3, and 5–11 is affirmed.
The Examiner’s decision rejecting claim 12 is reversed.

DECISION SUMMARY
In summary:
Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1, 3, 5–9 103 AAPA, Moon 1, 3, 5–9
10, 11 103 AAPA, Moon,
Wanlass
10, 11
12 103 AAPA, Merchant 12
Overall
outcome
1, 3, 5–11 12

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)(iv).

AFFIRMED-IN-PART