Ex Parte Kanamura et al

Patent Trial and Appeal Board

Nov 20, 2013

11186926 (P.T.A.B. Nov. 20, 2013)

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.
11/186,926 07/22/2005 Masahito Kanamura 050470 4230
23850 7590 11/20/2013
KRATZ, QUINTOS & HANSON, LLP
1420 K Street, N.W.
4th Floor
WASHINGTON, DC 20005
EXAMINER
KING, DOUGLAS
ART UNIT PAPER NUMBER
2824
MAIL DATE DELIVERY MODE
11/20/2013 PAPER
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.
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
_________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
__________

Ex parte MASAHITO KANAMURA
and TOSHIHIRO OHKI
__________

Appeal 2011-008804
Application 11/186,926
Technology Center 2800
___________

Before ADRIENE LEPIANE HANLON, CATHERINE Q. TIMM, and
JAMES C. HOUSEL, Administrative Patent Judges.

HANLON, Administrative Patent Judge.

DECISION ON APPEAL

Appeal 2011-008804
Application 11/186,926

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A. STATEMENT OF THE CASE
The Appellants appeal under 35 U.S.C. § 134 from an Examiner’s
decision finally rejecting claims 1, 2, 4, 7-9, 11, and 14. Claims 3, 5, 6, 10,
12, and 13 are also pending but have been withdrawn from consideration.
We have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM.
The claims on appeal are directed to a semiconductor device formed
from a III-V nitride family semiconductor and a method of fabricating the
semiconductor device. Representative claim 1 is reproduced below from the
Claims Appendix of the Appeal Brief dated September 13, 2010 (“App.
Br.”). The limitation at issue is italicized.
Claim 1. A semiconductor device formed from a III-V nitride
family semiconductor, comprising:
a semiconductor layer formed from the III-V nitride
family semiconductor;
a gate insulating film on the semiconductor layer;
a gate electrode on the gate insulating film; and
an insulating film covering the gate electrode and the
gate insulating film and having a specific dielectric constant
smaller than a specific dielectric constant of the gate insulating
film, the insulating film being not in direct contact with the
semiconductor layer,
wherein the gate insulating film is formed from one of a
tantalum oxide, a hafnium oxide, a hafnium aluminum oxide, a
lanthanum oxide, and a yttrium oxide.
Claims 1, 2, 4, 7-9, 11, and 14 stand rejected under 35 U.S.C. § 103(a)
as unpatentable over Sheppard1 in view of Ahn,2 Kang,3 and Mitani.4,5

1 U.S. 2006/0019435 A1, published January 26, 2006.
Appeal 2011-008804
Application 11/186,926

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The Appellants argue the claims on appeal as a group. Therefore, for
purposes of this appeal, claims 2, 4, 7-9, 11, and 14 stand or fall with the
patentability of claim 1. 37 C.F.R. § 41.37(c)(1)(vii) (2011).
B. ISSUE
The sole issue on appeal is whether the Examiner reversibly erred in
concluding that a semiconductor device comprising, inter alia, “an
insulating film covering the gate electrode and the gate insulating film”
wherein “the insulating film [is] not in direct contact with the semiconductor
layer” as recited in claim 1 is rendered obvious by the combination of
Sheppard and Mitani.6
C. DISCUSSION

2 U.S. 2002/0135048 A1, published September 26, 2002.
3 U.S. 7,081,409 B2, issued July 25, 2006.
4 U.S. 6,278,141 B1, issued August 21, 2001.
5 Claims 7 and 14 were omitted from the statement of the rejection. See
Final Office Action dated April 14, 2010 (“Final”), at 3; Examiner’s Answer
dated January 6, 2011 (“Ans.”), at 4. However, the Examiner addresses
these claims in the body of the rejection. Final 5; Ans. 6. The Appellants
recognize that claims 7 and 14 are subject to the § 103(a) rejection on
appeal. App. Br. 11. Therefore, the Examiner’s omission is harmless error,
and the statement of the rejection has been corrected to include claims 7 and
14.
6 The Examiner relies on Ahn and Kang to establish that “it would have been
obvious to one of ordinary skill in the art at the time of the invention to
replace the silicon dioxide gate insulating film of Sheppard with a known
“high-k” material such as tantalum oxide, hafnium oxide, hafnium aluminum
oxide, lanthanum oxide, or yttrium oxide in order to reduce leakage current.”
Ans. 5. The Appellants do not direct us to any error in the Examiner’s
findings of fact or conclusions of law as to Ahn or Kang in combination with
Sheppard.
Appeal 2011-008804
Application 11/186,926

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Referring to Sheppard Figure 3, the Examiner finds Sheppard
discloses a semiconductor device comprising a semiconductor layer formed
from the III-V nitride family (20, 22, 24), a gate insulating film (130) on the
semiconductor layer, and a gate electrode (32) on the gate insulating film.
Ans. 4. The Examiner finds Sheppard does not disclose an insulating film
covering the gate electrode as recited in claim 1. Ans. 5. Nonetheless, the
Examiner finds “the use of dielectric passivation layers covering gate
electrodes is known in the art.” Ans. 5. For support, the Examiner relies on
Mitani Fig. 12 which depicts a passivation layer (26) covering a gate
electrode (25A).7 Ans. 5.
According to the Examiner’s proposed modification of Sheppard, “the
passivation layer taught by Mitani would cover both the gate (32) and the
gate insulating layer (130) [of Sheppard] and not be in contact with the
semiconductor layer [(20, 22, 24)]” as recited in claim 1. Ans. 5.
The Appellants argue the passivation layer (26) of Mitani is in direct
contact with the cap layer (28). App. Br. 14. According to the Appellants:
The purpose of the passivation film (SiN) 26 of Mitani is stated
in column 7, line 21: “there is induced a compressive stress
field in the channel layer 23 by the passivation film 26.” That
is, Mitani’s passivation film 26 must be formed directly on the
semiconductor device layer. Mitani’s device would not have a
gate insulating film between the semiconductor layers and the
passivation film. Therefore, there is no suggestion in either

7 The Examiner also finds the passivation layer (26) of Mitani is a silicon
nitride layer and finds “Silicon Nitride is known in the art to have a lower
dielectric constant than those gate insulating materials suggested by Ahn and
Kang.” Ans. 5. The Appellants do not direct us to any error in the
Examiner’s findings.
Appeal 2011-008804
Application 11/186,926

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Mitani or Sheppard to form a SiN passivation layer at the
proposed location (top of Fig. 3) of Sheppard.

App. Br. 14 (emphasis in original omitted).
In response, the Examiner recognizes that “Mitani teaches that a stress
field is caused by the presence of layer 26.” Ans. 8. However, the Examiner
contends that “Mitani does not state that this effect is the purpose of layer
26.” Ans. 9. In this regard, the Examiner directs our attention to a prior art
device disclosed in Mitani wherein a passivation film 14 is provided on a
channel layer 12 so as to cover a gate electrode 13A and ohmic electrodes
13B and 13C. Ans. 9; Mitani, col. 1, ll. 61-64. The Examiner contends that
the motivation to cover the gate (32) and the gate insulating layer (130) of
Sheppard with a passivation layer “is implied by the term. . . . That is to say,
a passivation layer renders an active element passive as is implied by
‘passivation.’” Ans. 9 (emphasis in original omitted). The Examiner finds
that “[w]hen a passivation layer is placed over metal layers, such as gate
contacts, the passivation layer acts to prevent the layers it coats from
interacting with other materials (e.g. prevents chemical reactions, prevents
electrical contact – insulates, etc.).” Ans. 9.
The Examiner continues:
One of ordinary skill looking at the Mitani reference
would immediately recognize the benefits of implementing
such a passivation layer which are at the very least implied by
the term. The same person of ordinary skill looking at the
device of Sheppard would have reason to implement the layer
in order to passivate the metal contacts of Sheppard as is done
in Mitani. To determine that one of ordinary skill would not
have reason to combine having seen the implementation by
Mitani and having read the term passivation is to assume a level
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Application 11/186,926

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of ordinary skill that is inconsistent with the cited art—
including Appellant’s disclosure.

Ans. 10. The Appellants do not address the Examiner’s reasoning in the
Reply Brief.
Based on the foregoing, the weight of the evidence supports the
Examiner’s conclusion of obviousness. The Examiner merely relies on
Mitani to establish that passivation layers were known in the art at the time
of the Appellants’ invention. The Examiner finds one of ordinary skill in the
art would have been motivated to cover the gate (32) and the gate insulating
layer (130) of Sheppard with a passivation layer in the proposed manner to
yield the predictable result of preventing interaction with other materials.
See KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007) (“The
combination of familiar elements according to known methods is likely to be
obvious when it does no more than yield predictable results.”). The
Appellants have not directed us to any evidence to the contrary.
The § 103(a) rejection is sustained.
C. DECISION
The decision of the Examiner is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).

AFFIRMED

cdc