Ex Parte Hull et al

Patent Trial and Appeal Board

Oct 26, 2016

13608350 (P.T.A.B. Oct. 26, 2016)

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.
13/608,350 09/10/2012 Brett Adam Hull 5308-1078CT 3327
20792 7590 10/27/2016
MYERS BIGEL, P.A.
PO BOX 37428
RALEIGH, NC 27627
EXAMINER
KHAN, FARID H
ART UNIT PAPER NUMBER
2826
MAIL DATE DELIVERY MODE
10/27/2016 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 BRETT ADAM HULL and
QINGCHUN ZHANG
____________________

Appeal 2015-004602
Application 13/608,350
Technology Center 2800
____________________

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

PER CURIAM.

DECISION ON APPEAL1

STATEMENT OF THE CASE
Appellants2 filed an appeal under 35 U.S.C. § 134 from the
Examiner’s decision finally rejecting claims 2, 3, 5–9, 11, 12, 14–17, 31, and

1 Our decision refers to the Specification filed Sept. 10, 2012 (Spec.), the
Final Office Action mailed Feb. 26, 2014 (Final Act.), Appellants’ Appeal
Brief filed July 10, 2014 (Appeal Br.), the Examiner’s Answer mailed Jan.
14, 2015 (Ans.), and Appellants’ Reply Brief filed Mar. 12, 2015 (Reply
Br.).
2 Appellants identify the real party in interest as Cree, Inc. Appeal Br. 1.
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323 under 35 U.S.C. § 103(a) as being unpatentable over Mitsuhiro4 in view
of Kusumoto5 and rejecting claims 4 and 13 under 35 U.S.C. § 103(a) as
being unpatentable over Mitsuhiro and Kusumoto and further in view of
Kumar.6 We have jurisdiction under 35 U.S.C. §§ 6(b) and 134(a).
We AFFIRM.
The claims on appeal are directed to semiconductor devices (see, e.g.,
claims 2, 5, 9, and 12). Appellants’ Figure 4A is reproduced below.

Figure 4A is a cross-section of a semiconductor device.

Figure 4A depicts a double diffused metal oxide semiconductor field
effect transistor (DMOSFET) including a semiconductor layer 101 having a
first conductivity type (e.g., n-type conductivity), source/drain terminal

3 Claims 35–38 have been indicated as including allowable subject matter
and claims 18–30, 33, 34, and 39 have been allowed.
4 Mitsuhiro et al., JP 2002-270837 A, published Sept. 20, 2002
(“Mitsuhiro”), as translated.
5 Kusumoto et al., US 2005/0001217 A1, published Jan. 6, 2005
(“Kusumoto”).
6 Kumar et al., US 6,573,534 B1, issued June 3, 2003 (“Kumar”).
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regions 107 of the first conductivity type, and well regions 109 of a second
conductivity type (e.g., p-type conductivity). Spec. p. 10, ll. 9–19. An
epitaxial semiconductor layer 111 is provided on the surface 103 of the
semiconductor layer 101, with the epitaxial semiconductor layer 111
including source/drain terminal contact regions 115 of the first conductivity
type. Spec. p. 10, ll. 24–27. Ohmic contacts 117 are provided on the
terminal contact regions 115 and a gate insulating layer 119 and gate
electrode 121 are provided on the epitaxial semiconductor layer 111. Spec.
p. 10, l. 30 to p. 11, l. 3. Well contact regions 125 of the second
conductivity type may also be provided through the terminal contact regions
115 to provide electrical contact between ohmic contacts 117 and well
regions 109. Spec. p. 11, ll. 8–11.
Appellants disclose controlling the gate electrode 121 so portions of
well regions 109 adjacent surface 103 of the semiconductor layer 101
between terminal regions 107 and the outer perimeter of the well regions
109 define a channel so current may flow between ohmic contacts 117, 125
through terminal contact regions 115, terminal regions 107, channels of well
regions 109, the epitaxial semiconductor layer 111, and the semiconductor
layer 101. Spec. p. 11, ll. 24–29.
Independent claim 2 is illustrative of the subject matter on appeal.
Claim 2 is reproduced from the Claims Appendix of the Appeal Brief with
limitations at issue in the appeal italicized:
2. A semiconductor device comprising:
a semiconductor layer having a first conductivity type;
a well region of a second conductivity type in the
semiconductor layer wherein the first and second conductivity
types are different;
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a terminal region of the first conductivity type in the well
region;
an epitaxial semiconductor layer on a surface of the
semiconductor layer including the well region and the terminal
region wherein the epitaxial semiconductor layer has the first
conductivity type on the terminal region and portions of the
well region surrounding the terminal region at the surface of the
semiconductor layer, and wherein the epitaxial semiconductor
layer extends across an entirety of the well region and the
terminal region at the surface of the semiconductor layer;
a gate electrode on the epitaxial semiconductor layer so
that the epitaxial semiconductor layer is between the gate
electrode and portions of the well region surrounding the
terminal region at the surface of the semiconductor layer; and
an ohmic contact on the epitaxial semiconductor layer,
wherein the epitaxial semiconductor layer includes a terminal
contact region of the first conductivity type therethrough
providing electrical contact between the ohmic contact and the
terminal region, and wherein the epitaxial semiconductor layer
includes a well contact region of the second conductivity type
therethrough providing electrical contact between the ohmic
contact and the well region.

Appeal Br. 12 (Claims App’x) (emphasis added).

OPINION
Obviousness Rejection over Mitsuhiro and Kusumoto
Claims 2, 3, 5–9, 11, 12, 14–17, 31, and 32 are rejected under 35
U.S.C. § 103(a) as being unpatentable over Mitsuhiro in view of Kusumoto.
Appellants do not substantively argue the claims separately. Appeal Br. 4–
11. We select claim 2 as representative for discussing the issues on appeal.
The dispositive issue on appeal is whether Appellants have
demonstrated the combination of Mitsuhiro and Kusumoto does not disclose
or suggest an epitaxial semiconductor layer including “a well contact region
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of the second conductivity type therethrough providing electrical contact
between the ohmic contact and the well region,” as recited in claim 2.
Figure 6(c) of Mitsuhiro is reproduced below.

Figure 6(c) depicts a step in a manufacturing process for a MOSFET

Figure 6(c) is a cross-section of a semiconductor device including a
drain electrode 10, an n+-type board 1, an n--type epilayer 2, a p-type base
region 3, an n+-type source region 4, a surface channel layer 5, a contact
layer 22, a gate oxide 6, a gate electrode 7, and a source electrode 9.
Mitsuhiro ¶¶ 31–35, 41, 43–45.
The Examiner finds the n--type epilayer 2 functions as a
semiconductor layer, the p-type base region 3 functions as a well region, and
the n+-type source region 4 serves as a terminal region. Final Act. 3. The
Examiner further finds the surface channel layer 5 and contact layer 22
function as an epitaxial semiconductor layer that extends across an entirety
of the well region (the p-type base region 3) and the terminal region (the n+-
type source region 4) at a surface of the semiconductor layer (the n--type
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epilayer 2). Final Act. 3–4. The Examiner finds the epitaxial semiconductor
layer of Mitsuhiro includes a terminal contact region (i.e., contact layer 22)
therethrough to provide electrical contact between an ohmic contact (source
electrode 9) and the terminal region (the n+-type source region 4). Final Act.
4.
The Examiner finds Mitsuhiro does not show the well contact portion
of the device. Final Act. 4.
The Examiner finds Kusumoto discloses an epitaxial semiconductor
layer and a well contact region, citing Figures 1 and 4B of Kusumoto.
Figure 4B of Kusumoto is reproduced below.

Figure 4B depicts a cross-sectional view of a semiconductor device

The semiconductor device includes a SiC layer 2, a p-well region 3, a
p+ contact region 4, an epitaxially grown layer 5, a source region 6, a gate
electrode 10, and a source electrode 8. Kusumoto ¶ 65. The Examiner finds
the p+ contact region 4 serves as a well contact region that provides
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electrical contact between the ohmic contact 8 and the p-well region 3. Final
Act. 4–5. The Examiner concludes it would have been obvious to modify
the device of Mitsuhiro in view of Kusumoto to make a functional
semiconductor device. Final Act. 5.
Appellants argue Kusumoto does not disclose or suggest either the
terminal contact region or the well contact region through the epitaxially
grown layer, as required by claim 2. Appeal Br. 8. In particular, Appellants
contend Kusumoto discloses a source electrode 8 that passes through the
epitaxially grown layer 5 to reach the source region 6 and the p+ contact
region 4. Appeal Br. 8; Reply Br. 2–4. Thus, the p+ contact region 4 of
Kusumoto does not extend through the epitaxially grown layer 5 and the
combination of Mitsuhiro and Kusumoto does not disclose or suggest the
structure of claim 2. Appeal Br. 8–9.
Appellants’ arguments are unpersuasive of reversible error. First,
Appellants’ argument that Kusumoto does not disclose a terminal contact
region, as recited in claim 2, does not address the Examiner’s rejection
because the Examiner finds the epitaxial semiconductor layer of Mitsuhiro
includes a terminal contact region (i.e., contact layer 22). Final Act. 4.
Second, Appellants’ argument that Kusumoto discloses a well contact
region that does not extend through an epitaxial layer does not properly
address the Examiner’s finding of a suggestion within the combination of
Mitsuhiro and Kusumoto of extending a well contact region in a device
having the epitaxial layers 5 and 22 of Mitsuhiro.
The Examiner explains Figure 6(a) of Mitsuhiro depicts a half p-well.
Ans. 6. To construct a full p-well, one would place the structure of Figure
6(a) of Mitsuhiro side by side with the same structure. Ans. 7. The
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Examiner further explains that, in order to modify Mitsuhiro in view of
Kusumoto, a well contact region would necessarily pass through the
epitaxial layer (i.e., layers 5 and 22 of Mitsuhiro) so an electrical contact is
made between the source electrode, the source region, and the well contact
region. Ans. 7.
As noted above, the Examiner finds the source electrode 9 of
Mitsuhiro functions as an ohmic contact. Final Act. 4. Moreover, as shown
in Figure 6(c) of Mitsuhiro above, the source electrode 9 of Mitsuhiro is
located above the epitaxial layer 5. Therefore, in order for Mitsuhiro to be
modified in view of Kusumoto to include a well contact region that provides
an electrical contact between an ohmic contact (i.e., source electrode 9 of
Mitsuhiro) and a well region (i.e., p-type base region 3 of Mitsuhiro), the
well contact region must extend from the source electrode 9 of Mitsuhiro,
which is located above the epitaxial layer 5, through the epitaxial layer 5 to
the p-type base region 3 below. The Examiner further explains modifying
Mitsuhiro to include a well contact region would prevent the p-well of
Mitsuhiro from electrically floating and would permit the p-well to be
electrically biased by a voltage supplied via the well contact region and the
ohmic contact. Ans. 7.
In response to the Examiner’s explanation, Appellants restate their
argument that Mitsuhiro does not disclose a well contact region and
Kusomoto discloses a source electrode 8 that extends through the epitaxially
grown layer 5 to the p+ contact region 4 below. Reply Br. 4. Appellants
contend the Examiner’s explanation contradicts the disclosure of Kusumoto,
which discloses a p+ contact region 4 not included in the epitaxially grown
layer 5. Reply Br. 5.
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Appellants’ arguments focus upon what Kusumoto alone would have
suggested to one of ordinary skill in the art by noting Kusomoto’s disclosure
of a source electrode 8 that extends through the epitaxially grown layer 5 to
the p+ contact region 4. However, “the test for combining references is not
what the individual references themselves suggest but rather what the
combination of disclosures taken as a whole would suggest to one of
ordinary skill in the art.” In re McLaughlin, 443 F.2d 1392, 1395 (CCPA
1971). As explained by the Examiner, the combination of the disclosure of
Mitsuhiro, which discloses an ohmic contact (i.e., source electrode 9)
located above an epitaxial semiconductor layer (i.e., surface channel layer 5)
and a well region (i.e., the p-type base region 3), and the disclosure of
Kusumoto, which discloses a well contact region (i.e., p+ contact region 4),
would have suggested to one of ordinary skill in the art a well contact region
extending from the ohmic contact of Mitsuhiro through the epitaxial
semiconductor layer below to the well region.
Therefore, Appellants’ arguments do not demonstrate that the
combination of Mitsuhiro and Kusumoto does not disclose or suggest an
epitaxial semiconductor layer including “a well contact region of the second
conductivity type therethrough providing electrical contact between the
ohmic contact and the well region,” as recited in claim 2.
Appellants further contend Kusumoto teaches away from forming a
well contact region through an epitaxial semiconductor layer because
Kusumoto teaches away from forming a source region 6 through the
epitaxially grown layer 5. Appeal Br. 9; Reply Br. 5. This argument is also
unpersuasive of reversible error. “A reference does not teach away . . . if it
. . . does not ‘criticize, discredit, or otherwise discourage’ investigation into
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the invention claimed.” DePuy Spine, Inc. v. Medtronic Sofamor Danek,
Inc., 567 F.3d 1314, 1327 (Fed. Cir. 2009) (quoting In re Fulton, 391 F.3d
1195, 1201 (Fed. Cir. 2004)). Appellants have not directed us to a
disclosure, whether by Mitsuhiro or Kusumoto, criticizing, discrediting, or
otherwise discouraging a well contact region extending from an ohmic
contact through an epitaxial semiconductor layer to a well region when the
ohmic contact is located above the epitaxial semiconductor layer, as in the
disclosure of Mitsuhiro.
Appellants do not argue claims 3, 5–9, 11, 12, 14–17, 31, and 32
separately from claim 2. Appeal Br. 10–11.
For the reasons discussed above and those set forth in the Examiner’s
Answer, we sustain the Examiner’s § 103 rejection of claims 2, 3, 5–9, 11,
12, 14–17, 31, and 32 over Mitsuhiro in view of Kusumoto.

Obviousness Rejection over Mitsuhiro, Kusumoto, and Kumar
Claims 4 and 13 are rejected under 35 U.S.C. § 103(a) as being
unpatentable over Mitsuhiro and Kusumoto and further in view of Kumar.
Appellants do not advance separate arguments directed to the Examiner’s
additional findings and conclusions based upon Kumar. Therefore, we
sustain the Examiner’s § 103(a) rejection of claims 4 and 13 over the
combination of Mitsuhiro, Kusumoto, and Kumar.

DECISION
The decision of the Examiner rejecting claims 2–9, 11–17, 31, and 32
under 35 U.S.C. § 103(a) is affirmed.
No time period for taking any subsequent action in connection with
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this appeal may be extended under 37 C.F.R. § 1.136(a)(1).

AFFIRMED