Ex Parte ZHANG et al

Patent Trials and Appeals Board

Mar 13, 2019

14286202 - (D) (P.T.A.B. Mar. 13, 2019)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
14/286,202 05/23/2014
23494 7590 03/15/2019
TEXAS INSTRUMENTS IN CORPORA TED
PO BOX 655474, MIS 3999
DALLAS, TX 75265
FIRST NAMED INVENTOR
YONGXI ZHANG
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
ATTORNEY DOCKET NO. CONFIRMATION NO.
TI-72758 1687
EXAMINER
PARK, SAMUEL
ART UNIT PAPER NUMBER
2818
NOTIFICATION DATE DELIVERY MODE
03/15/2019 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):
uspto@ti.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte YONGXI ZHANG, PHILIP L. HOWER, SAMBER P.
PENDHARKAR, JOHN LIN, GURU MATHUR, SCOTT BALSTER, and
VICTOR SINOW
Appeal2017-005556
Application 14/286,202
Technology Center 2800
Before CATHERINE Q. TIMM, WESLEY B. DERRICK, and
CHRISTOPHER L. OGDEN, Administrative Patent Judges.
DERRICK, Administrative Patent Judge.
DECISION ON APPEAL
Appeal2017-005556
Application 14/286,202
STATEMENT OF THE CASE
1
Appellant2 seeks review under 35 U.S.C. § I34(a) from the
maintained rejection under 35 U.S.C. § 103 of claims 10-13, 15, and 18-20
over Lotfi3 in view ofChen. 4' 5 We have jurisdiction under 35 U.S.C. § 6(b).
We REVERSE.
THE INVENTION
The subject matter of the claims on appeal relates to a semiconductor
device. Spec., Abstract.
Claim 10, the sole independent claim, is representative:
10. A method, comprising:
providing a transistor having double isolation formed in a
semiconductor surface of a substrate doped with a first dopant
type, said transistor including:
a source region doped with a second dopant type;
a drain region including a drain drift region doped with
said second dopant type;
a gate stack including a gate electrode on a gate dielectric
between said source region and said drain region;
1 We refer to the Specification filed May 23, 2014 ("Spec."), the Final
Office Action dated October 30, 2015 ("Final Act."), the Appeal Brief filed
September 14, 2016, the Advisory Action dated September 23, 2016 ("Adv.
Act."), the Examiner's Answer dated December 15, 2016 ("Ans."), and the
Reply Brief filed February 15, 2017 ("Reply Br.").
2 Appellant is the Applicant, Texas Instruments Incorporated, which,
according to the Appeal Brief, is the real party in interest. Appeal Br. 2.
3 Lotfi et al., US 2011/0049621 Al, published March 3, 2011.
4 Chen et al., US 2014/0061731 Al, published March 6, 2014.
5 Prior pending claims 1-9, 14, 16, and 17 were cancelled (Adv. Act.),
obviating previously pending rejections of claims 1-9 and of claim 17 (Final
Act. 3-10, 16-17).
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Application 14/286,202
a first isolation region doped with said first dopant type;
said source region and said drain region being enclosed
by said first isolation region, and
a second isolation region doped with said second dopant
type enclosing said first isolation region, and
electrically floating said second isolation region while
operating said transistor.
App. Br. (Claims Appendix), 10.
DISCUSSION
On this record, having reviewed the grounds set forth by the
Examiner, Appellant's arguments, and the Examiner's response, we are
persuaded that the Examiner has failed to establish that the claims are
unpatentable.
For any ground of rejection, "the [E]xaminer bears the initial burden
... of presenting a prim a facie case of unpatentability." In re Oetiker, 977
F.2d 1443, 1445 (Fed. Cir. 1992).
The Examiner relies on Lotfi for its disclosure to provide a transistor,
N-LDMOS, formed in a semiconductor surface of substrate. Final Act. 10
(citing Lotfi ,r,r 120-132, Fig. 18). The Examiner cites Lotfi for element 530
as a p-type element, which is relied on for the substrate being doped with a
first dopant. Id. (citing Lotfi ,r 120, Fig. 18). As to the transistor, the
Examiner cites to element 562 for a source region doped with a second
doping type (id. (citing Lotfi ,r 122, Fig. 18)), element 545 for a drain region
including a drain drift region (id. (citing Lotfi ,r,r 121, 128, Fig. 18)), and
elements 535 and 545 for a gate stack including a gate electrode 540 on a
gate dielectric 535 (id. at 10-11 (citing Lotfi 120, Fig. 18)). The Examiner
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Application 14/286,202
notes that elements 545 & 562 are on both the left and right of element 540.
Id. at 11 ( citing Lotfi, Fig. 18).
Id.
The Examiner concedes that
Lotfi does not disclose a first isolation region doped with a
second dopant type; said source region and said drain region
being enclosed by said first isolation region, and a second
isolation region doped with said second dopant type enclosing
said first isolation region, and electrically floating said second
isolation region while operating said transistor.
The Examiner turns to Chen to remedy the identified deficiencies. Id.
at 11-12. The Examiner relies on Chen as disclosing a first isolation
region----elements 42, 44, and 46 in combination----doped with said first
dopant type, i.e., with p-type doping. Id. at 11 ( citing Chen ,r,r 20, 31, Fig.
1 ). The Examiner maintains that the first isolation region, formed from
elements 42, 44, and 46, enclose device area element 28. Id. ( citing Chen
,r 31, Figs. 1, 2). As to the second isolation region, the Examiner maintains
that substrate contact region 7 4 meets the claim limitation because Chen, in
stating that "semiconductor substrate 22 may be biased via one or more
substrate contact regions 74," means that "it may also not be biased" and
that this "would make element 74 floating) [sic]." Id. As to being doped
with a second dopant, the Examiner relies on element 74 being an n-type
because "substitution of semiconductor regions of opposite conductivity
type can be performed." Id. ( citing Chen ,r 20, Fig. 1 ).
The Examiner concludes:
It would have been obvious to one of ordinary skill in the art at
the time of the invention to incorporate the isolations & metal
layers of Chen into the semiconductor device of Lotfi because
the combined device would help in preventing breakdown
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Application 14/286,202
during, e.g., high-side operation, and punch-through prevention,
as well as, support the formation of an integrated device ....
Id. at 12 ( citing Chen ,r,r 27-29).
Appellant contends that the Examiner has failed to establish a prima
facie case of obviousness. App. Br. 3-9. Appellant argues that Chen
discloses a single isolation tub 40 formed from an NBL layer 42, n-type
isolating wells 44, and link regions 46. Id. at 5-6 (citing Chen ,r,r 7, 21, 27,
37, 43, Fig. 1). Further, Appellant argues that because then-type buried
layer (NBL) 42 in Chen does not have the same doping as the substrate, i.e.,
p-type, it does not correspond to the "first isolation region" of claim 10 as
relied on by the Examiner. Id. at 6. The example device depicted in Chen's
Figure 1 is disclosed as having a "semiconductor substrate 22 includ[ing] a
single p-type epitaxial layer 24 grown on an original substrate 26 ...
[which] may be a lightly or heavily doped p-type substrate." Chen ,r 21.
The Examiner does not squarely address Appellant's position, but
rather maintains that Lotfi "discloses a substrate with the first dopant type
and the combination of Chen ... incorporates a first isolation region with the
first dopant type." Ans. 4. The relied on substrate from Lotfi (element 530),
however, is also a p-type element and, thus, raises the same issue with the
NBL layer 42 in the combination as it does in Chen. See Final Act. 10
( citing Lofti ,r 120, Fig. 18).
Appellant also argues that the substrate contact regions 7 4 do not meet
the recited "second isolation region" because they do not function as
isolation regions and they are not doped with different dopant types than the
substrate. App. Br. 7. The substrate contact regions 74 in Chen's Figure 1
are P+ (Chen, Fig. 1) and the substrate, as explained above, is p-doped (id.
,r 21 ).
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Application 14/286,202
The Examiner responds that Appellant's argument is conclusory and
not sufficiently supported, that the claims do not require a particular type of
isolation, and that the conductivity type can be switched to opposite
conductivity type, that is, that the "isolation region of element 7 4 is
incorporated as a second conductivity type n-type." Ans. 5 ( citing Chen
,r 20, Fig. 1 ). The Examiner further relies on "element 7 6 [being] the same
conductivity type as element 7 4, and elements 44 & 46 & 42 [being] the
opposite conductivity type as that of elements 7 4 & 7 6 such that there is a
junction of opposite conductivity for isolation, PN-junction." Id. ( citing
Chen ,r 43).
The Examiner's positions are not well founded on this record. As
highlighted by Appellant, it is manifest that the contact regions 7 4 in Chen
function to bias the semiconductor substrate and that is contrary to
functioning as an isolation region. Reply Br. 2; see also App. Br. 7-8. As
to the type of isolation, while contending it is not limited to any particular
type, the Examiner relies on electrical isolation in that the lack of biasing
suffices. Final Act. 11. The Examiner fails, however, to establish a
sufficient basis for any combination in which element 7 4 functions, alone or
with other elements, as an isolation region, including that grounded on a lack
of biasing. As to switching the conductivity type of element 74 to an n-type,
it is grounded on a general disclosure in paragraph 20 of Chen, but there is
no particular reasoning set forth by the Examiner sufficient to support that it
would have been obvious to do so within the meaning of 35 U.S.C. § 103.
See, e.g., Belden v. Berk-TekLLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015)
("[O]bviousness concerns whether a skilled artisan not only could have
made but would have been motivated to make the combinations or
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Application 14/286,202
modifications of prior art to arrive at the claimed invention."). Further, the
Examiner has not sufficiently explained how incorporating n-type material
as element 74 would provide an opposite conductivity type as that of
elements 42, 44, & 46 where, as explained above, element 42 is an n-buried
layer (NBL ). Still further, as highlighted by Appellant, the Examiner has
failed to sufficiently establish a basis for forming a PN junction that would
function as an isolation element, and citation to Chen's paragraph 43 does
not suffice. Ans. 5; Reply Br. 2-3.
For these reasons, we do not sustain the rejection of independent
claim 10. Accordingly, we reverse the rejection of all claims on appeal.
DECISION
The Examiner's decision rejecting claims 10-13, 15, and 18-20 is
REVERSED.
REVERSED
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