Cree, Inc.

Patent Trials and Appeals Board

Sep 24, 2021

2020006426 (P.T.A.B. Sep. 24, 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.
14/212,991 03/14/2014 Vipindas Pala 1194-195 8249
27820 7590 09/24/2021
WITHROW & TERRANOVA, P.L.L.C.
106 Pinedale Springs Way
Cary, NC 27511
EXAMINER
CHEN, DAVID Z
ART UNIT PAPER NUMBER
2815
NOTIFICATION DATE DELIVERY MODE
09/24/2021 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):
patents@wt-ip.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte VIPINDAS PALA, EDWARD ROBERT VAN BRUNT, and
LIN CHENG
Appeal 2020-006426
Application 14/212,991
Technology Center 2800
Before MICHAEL P. COLAIANNI, DONNA M. PRAISS, and
JENNIFER R. GUPTA, Administrative Patent Judges.
GUPTA, Administrative Patent Judge.
DECISION ON APPEAL1
Pursuant to 35 U.S.C. § 134(a), Appellant2 appeals from the
Examiner’s decision to reject claims 1, 4, 6–10, 12, 13, 16, and 18–24.3 We
have jurisdiction under 35 U.S.C. § 6(b).

1 In this Decision, we refer to the Specification filed March 14, 2014
(“Spec.”); the Final Office Action dated October 28, 2019 (“Final Act.”); the
Appeal Brief filed January 28, 2020 (“Appeal Br.”); the Examiner’s Answer
dated July 24, 2020 (“Ans.”); and the Reply Brief dated September 15, 2020
(“Reply Br.”).
2 “Appellant” refers to “applicant” as defined in 37 C.F.R. § 1.42. Appellant
identifies the real party in interest as Cree, Inc. Appeal Br. 1.
3 Claims 2, 3, 5, 11, 14, 15, 17, and 26–29 are cancelled. Appeal Br. 11–15
(Claims App.). Claim 25 is withdrawn from consideration by the Examiner
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We AFFIRM.
CLAIMED SUBJECT MATTER
The claims are directed to an insulated gate bipolar transistor (IGBT)
device. Spec. ¶ 1. Independent claim 1, reproduced below, illustrates the
claimed subject matter:
1. An insulated gate bipolar transistor (IGBT) device
comprising:
• a silicon carbide (SiC) IGBT stack, wherein the SiC
IGBT stack includes:
• an injector region;
• a drift region over the injector region;
• a spreading region over the drift region, the
spreading region providing a first surface of the
SiC IGBT stack opposite the drift region and
having a doping concentration that is greater than
a doping concentration of the drift region; and
• a pair of junction implants in the spreading
region, wherein:
• the pair of junction implants are separated
by a channel and extend from the first
surface of the SiC IGBT stack along a
lateral edge of the SiC IGBT stack towards
the drift region to a first depth; and
• the thickness of the spreading region is
more than two and a half times greater and
less than four times greater than the first
depth;

as drawn to a non-elected invention. Non-Final Office Action dated October
8, 2015, 2.
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Application 14/212,991

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• a gate contact and an emitter contact on the first surface
of the SiC IGBT stack; and
• a collector contact on a second surface of the SiC IGBT
stack, which is provided by the injector region opposite
the drift region.
Appeal Br. 11 (Claims App.).
REJECTIONS
The Examiner maintains the following rejections on appeal (Ans. 3;
Final Act. 9–24):
Rejection I: Claims 1, 4, 6–10, 12, 13, 16, and 18–24 are rejected
under 35 U.S.C. § 112(a) as failing to comply with the written description
requirement.
Rejection II: Claims 1, 4, 6–10, and 12 are rejected under 35 U.S.C.
§ 103 as unpatentable over Zhang4 and Ryu.5
Rejection III: Claims 13, 16, and 18–23 are rejected under 35 U.S.C.
§ 103 as unpatentable over Shimizu6 and Ryu ’335.7
Rejection IV: Claim 24 is rejected under 35 U.S.C. § 103 as
unpatentable over Shimizu, Ryu ’335, and Ryu.
DISCUSSION
After reviewing the evidence in light of the Appellant’s and the
Examiner’s opposing positions, we determine that Appellant has not
identified reversible error in the Examiner’s rejections. Thus, we sustain the

4 Zhang, US 2010/0140628 A1, published June 10, 2010.
5 Ryu, US 2004/0119076 A1, published June 24, 2004.
6 Shimizu et al., US 2014/0284621 A1, published September 25, 2014.
7 Ryu et al., US 2010/0301335 A1, published Dec. 2, 2010.
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Examiner’s rejections for the reasons expressed in the Final Office Action
and the Answer. We add the following primarily for emphasis.
Rejection I – Written Description
The Examiner finds that the limitation “more than two and a half
times and less than four times greater than the first depth” is not disclosed in
the originally filed Specification. Final Act. 9—10.
Appellant argues that the Specification includes examples with the
thickness of the spreading region (56) being between 1.5 to 4 times greater
than the depth of the base wells and the thickness of the spreading layer
being at least 1.5 μm to 10.0 μm greater than the depth of the base wells.
Appeal Br. 6. Regarding the recitation “more than two and half times
greater,” Appellant argues that Appellant’s Specification clearly discloses a
first depth of the base well (64) that can be between 0.5 μm to 1.5 μm and
that a thickness of the spreading region (56) can extend at least 1.5 μm
beyond the first depth. Reply Br. 3; Spec. ¶ 33. Appellant argues that for a
1.0 μm value of the first depth (or a midpoint of the provided range for DB),
the spreading layer would then extend at least 1.5 μm beyond the first depth
to clearly disclose a thickness of the spreading region 56 of at least 2.5 μm,
which is at least 2.5 times the first depth. Id.
“[T]he test for [compliance with the written description requirement]
is whether the disclosure of the application relied upon reasonably conveys
to those skilled in the art that the inventor had possession of the claimed
subject matter as of the filing date.” Ariad Pharm., Inc. v. Eli Lilly & Co.,
598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc).
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We are not persuaded by Appellant’s arguments that Appellant was in
possession of the range “more than two and a half times greater and less than
four times greater” recited in claim 1. Although a thickness of the spreading
region (56) of at least 2.5 μm, which is at least 2.5 times the first depth when
the first depth of the base well (64) is 1.0 μm, can be calculated from the
Specification’s disclosure, this is not adequate disclosure of the thickness of
the spreading region is “more than two and a half times greater” than the
first depth. See Purdue Pharma LP v. Faulding Inc., 230 F.3d 1320, 1326–
27 (Fed. Cir. 2000) (“[O]ne cannot disclose a forest in the original
application, and then later pick a tree out of the forest and say here is my
invention. In order to satisfy the written description requirement, the blaze
marks directing the skilled artisan to that tree must be in the originally filed
disclosure.”) (citing In re Ruschig, 379 F.2d 990, 994–95 (CCPA 1967); see
also Martin v. Mayer, 823 F.2d 500, 505 (Fed. Cir. 1987) (“[It is] not a
question of whether one skilled in the art might be able to construct the
patentee’s device from the teachings of the disclosure . . . . Rather, it is a
question whether the application necessarily discloses that particular
device.”) (quoting Jepson v. Coleman, 314 F.2d 533, 536 (CCPA 1963)).
Here, Appellant’s Specification at best provides a generic description
that encompasses the thickness of the spreading region is “more than two
and a half times greater” than the first depth, without sufficient specific
guidance, or blaze marks, directing a skilled artisan to the particular range of
“the thickness of the spreading region is more than two and a half times
greater and less than four times greater than the first depth.” Accordingly,
we agree with the Examiner that the Specification does not provide
sufficient support to inform one of ordinary skill in the art that Appellant
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was in possession of the limitation “two and a half times greater and less
than four times greater” recited in claim 1.
Rejection – Obviousness over Zhang and Ryu
The Examiner finds that Zhang teaches claim 1’s insulated gate
bipolar transistor (IGBT) device, but fails to teach “the thickness of the
spreading region is more than two and a half times greater and less than four
times greater than the first depth.” Final Act. 11–12 (citing Zhang ¶¶ 30, 33–
36, 44–48, 55, Figs. 1–2).
The Examiner finds that Ryu teaches the thickness of the spreading
region (26) having a JFET region (26) (about 1 μm, Ryu ¶ 41) is more than
two and a half times greater and less than four times greater than the first
depth of the junction implants (20) (about 0.3 μm, Ryu ¶ 42). The Examiner
determines that it would have been obvious to modify Zhang’s IGBT device
structure to have a thickness of the spreading region of more than two and a
half times greater and less than four times greater than the first depth
because Zhang teaches that the thickness and/or doping concentration of the
spreading region relative to the first depth are selected to provide a desired
tradeoff in device static and dynamic characteristics (Zhang ¶ 47). Final
Act. 12–13.
Appellant argues that the Examiner has admitted that neither Zhang
nor Ryu describe a thickness of the spreading region being more than 2.5
greater than a depth of the junction implants. Appeal Br. 8. Appellant argues
that a person skilled in the art at the time of Appellant’s invention would not
expect significant benefits from increasing the depth of the spreading region
to the thickness required by claim 1. Id.
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Appellant’s arguments do not identify reversible error in the
Examiner’s rejection. The Examiner clearly finds that Ryu teaches a broader
and overlapping thickness of the spreading region (26) (about 1 μm, Ryu
¶ 41) may be more than two and a half times greater and less than four times
greater the first depth of first depth of the junction implants (20) (about
0.3 μm, Ryu ¶ 42). Appellant’s argument that the benefits from increasing
the depth of the spreading region to the thickness required by claim 1 would
have been unexpected is not supported by sufficient objective factual
evidence. In re Lindner, 59 C.C.P.A. 920, 457 F.2d 506, 508, 173 USPQ
356, 358 (CCPA 1972) (“[M]ere lawyers’ arguments unsupported by factual
evidence are insufficient to establish unexpected results.”). Thus, we sustain
the § 103 rejection of claims 1, 4, 6–10, and 12 over Zhang and Ryu.
Rejection over Shimizu and Ryu
Claim 13 recites:
An insulated gate bipolar transistor (IGBT) device comprising:
• a silicon carbide (SiC) IGBT stack, wherein the SiC IGBT stack
includes:
• an injector region;
• a drift region over the injector region;
• a spreading region over the drift region, the spreading region
providing a first surface of the SiC IGBT stack opposite the drift
region and having a doping concentration that is greater than a
doping concentration of the drift region; and
• a pair of junction implants in the spreading region, wherein:
• the pair of junction implants are separated by a junction
field-effect transistor (JFET) region and extend from the
first surface of the SiC IGBT stack along a lateral edge of
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the SiC IGBT stack towards the drift region to a first
depth; and
• the spreading region extends beyond the first depth by at
least 3.0 μm and less than 10.0 μm;
• a gate contact and an emitter contact on the first surface of the
SiC IGBT stack; and
• a collector contact on a second surface of the SiC IGBT stack,
which is provided by the injector region opposite the drift region.
Appeal Br. 13 (Claims App.).
The dispute between the Examiner and Appellant revolves around
whether Shimizu teaches claim 13’s “spreading region.” Final Act. 17;
Appeal Br. 9.
The Examiner finds that Shimizu teaches a spreading region (14) over
the injector region (52). Final Act. 17–18; Shimizu ¶ 236.
Appellant argues that the Examiner is equating the “n-type SiC layer”
(14) in Shimizu and the spreading layer in claim 13, however, the “n-type
SiC layer” (14) in Shimizu is not over a drift layer (a layer having the same
doping type but a different doping concentration as the spreading layer), and
thus cannot be equivalent to the spreading layer. Appeal Br. 9.
Appellant’s argument does not identify reversible error in the
Examiner’s rejection. Shimizu teaches the n-type SiC layer 14 has the same
n-type impurity concentration and thickness as Appellant’s spreading region
56—an n-type impurity concentration of approximately 5 x 1015 to 2 x 1016
cm-3 and a thickness of approximately 5 to 10 μm. Compare Shimizu ¶ 236,
with Spec. ¶¶ 33, 36. Thus, we are not persuaded that the Examiner
reversibly erred in equating Shimizu’s n-type SiC layer (14) with claim 1’s
spreading layer. Accordingly, we sustain the § 103 rejection of claims 13,
16, and 18–23 over Shimizu and Ryu ’335.
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Rejection over Shimizu, Ryu ’335, and Ryu
Appellant argues that claim 24, the sole claim rejected over Shimizu,
Ryu ’335, and Ryu, is allowable at least by virtue of its dependence from
claim 13. Because we sustain the § 103 rejection of claim 13 over Shimizu
and Ryu ’335, we also sustain the § 103 rejection of claim 24 over Shimizu,
Ryu ’335, and Ryu.
CONCLUSION
The Examiner’s decision to reject claims 1, 4, 6–10, 12, 13, 16, and
18–24 is affirmed.
DECISION SUMMARY
In summary:
Claims
Rejected
35 U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1, 4, 6–10,
12, 13, 16,
18–24
112(a) Written
Description
1, 4, 6–10,
12, 13, 16,
18–24

1, 4, 6–10,
12
103 Zhang, Ryu 1, 4, 6–10,
12

13, 16, 18–
23
103 Shimizu, Ryu ’335 13, 16, 18–
23

24 103 Shimizu, Ryu
’335, Ryu
24
Overall
Outcome
1, 4, 6–10,
12, 13, 16,
18–24

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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