Ex parte Dutta

Board of Patent Appeals and Interferences

Apr 17, 2002

08812848 (B.P.A.I. Apr. 17, 2002)

The opinion in support of the decision being entered today was not written
for publication and is not binding precedent of the Board.
Paper No. 16
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte RANADEEP DUTTA
____________
Appeal No. 1999-2838
Application No. 08/812,848
____________
ON BRIEF
____________
Before RUGGIERO, DIXON, and BARRY, Administrative Patent Judges.
RUGGIERO, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on the appeal from the final rejection
of claims 1-14, which are all of the claims pending in the
present application. An amendment after final rejection filed
November 10, 1998, which amended claims 1 and 2, was approved
for entry by the Examiner.
The claimed invention relates to a structure for
terminating the active area of a high voltage semiconductor
device. More particularly, the termination structure includes a
Appeal No. 1999-2838
Application No. 08/812,848
The word “dose” is misspelled at line 15 of claim 1.1
2
plurality of very lightly doped spaced concentric P type
diffusion rings in the N epitaxial layer of the device
surrounding the outer periphery of the device active area. The
low dose P type diffusion rings have a concentration produced by
an implant dose of from about 2E12 to 2E13 atoms/cm which,2
according to Appellant (specification, page 3), serves to lower
the electric field at the surface of the epitaxial layer.
Claim 1 is illustrative of the invention and reads as
follows:1
1. A termination structure for a semiconductor die; said
semiconductor die having a body of silicon of one of the
conductivity types and an upper N epitaxial layer for receiving
diffusions therein; said N epitaxial layer having an active area
diffused therein; a first electrode means connected to said
active area; said active area having an outer periphery; said N
epitaxial area and said die having an outer peripheral street;
said first electrode and said street being connectable to
potential differences in excess of about 600 volts; said
termination structure comprising a plurality of spaced
concentric P type diffusion rings in said N epitaxial layer
surrounding said outer periphery of said active area to
distribute the electric field between said first electrode and
said street; said P type diffusion rings having a concentration
produced by an implant does [sic, dose] of from about 2E12 to
2E13 atoms/cm to reduce the electric field at the surface of2
said N epitaxial layer and to prevent their complete depletion
at full reverse voltage.
The Examiner relies on the following prior art:
Appeal No. 1999-2838
Application No. 08/812,848
The Appeal Brief was filed May 3, 1999 (Paper No. 12). In response to2
the Examiner’s Answer dated July 12, 1999 (Paper No. 13), a Reply Brief was
filed September 14, 1999 (Paper No. 14) which was acknowledged and entered by
the Examiner as indicated in the communication dated September 23, 1999 (Paper
No. 15).
3
Zommer 5,629,552 May 13,
1997 (filed Jan.
17, 1995)
Claims 1-14 stand finally rejected under 35 U.S.C. § 103(a)
as being unpatentable over Zommer.
Rather than reiterate the arguments of Appellant and the
Examiner, reference is made to the Briefs and Answer for the2
respective details.
OPINION
We have carefully considered the subject matter on appeal,
the rejection advanced by the Examiner and the evidence of
obviousness relied upon by the Examiner as support for the
rejection. We have, likewise, reviewed and taken into
consideration, in reaching our decision, Appellant’s arguments
set forth in the Briefs along with the Examiner’s rationale in
support of the rejection and arguments in rebuttal set forth in
the Examiner’s Answer.
Appeal No. 1999-2838
Application No. 08/812,848
4
It is our view, after consideration of the record before
us, that the evidence relied upon and the level of skill in the
particular art would not have suggested to one of ordinary skill
in the art the invention as set forth in the appealed claims 1-
14. Accordingly, we reverse.
In rejecting claims under 35 U.S.C. § 103, it is
incumbent upon the Examiner to establish a factual basis to
support the legal conclusion of obviousness. See In re Fine,
837
F.2d 1071, 1073, 5 USPQ2d 1596, 1598 (Fed. Cir. 1988). In so
doing, the Examiner is expected to make the factual
determinations set forth in Graham v. John Deere Co., 383 U.S.
1,
17, 148 USPQ 459, 467 (1966), and to provide a reason why one
having ordinary skill in the pertinent art would have been led
to
modify the prior art or to combine prior art references to
arrive
at the claimed invention. Such reason must stem from some
teaching, suggestion or implication in the prior art as a whole
Appeal No. 1999-2838
Application No. 08/812,848
5
or knowledge generally available to one having ordinary skill in
the art. Uniroyal Inc. v. Rudkin-Wiley Corp., 837 F.2d 1044,
1051, 5 USPQ2d 1434, 1438 (Fed. Cir.), cert. denied, 488 U.S.
825
(1988); Ashland Oil, Inc. v. Delta Resins & Refractories, Inc.,
776 F.2d 281, 293, 227 USPQ 657, 664 (Fed. Cir. 1985), cert.
denied, 475 U.S. 1017 (1986); ACS Hospital Systems, Inc. v.
Montefiore Hospital, 732 F.2d 1572, 1577, 221 USPQ 929, 933
(Fed.
Cir. 1984). These showings by the Examiner are an essential
part
of complying with the burden of presenting a prima facie case of
obviousness. Note In re Oetiker, 977 F.2d 1443, 1445, 24 USPQ2d
1443, 1444 (Fed. Cir. 1992).
With respect to claim 1, the sole independent claim on
appeal, Appellant asserts the Examiner’s failure to establish a
prima facie case of obviousness since all of the claim
limitations are not taught or suggested by the applied Zommer
reference. In particular, Appellant contends (Brief, page 13;
Reply Brief, page 4) that the Examiner has not convincingly
Appeal No. 1999-2838
Application No. 08/812,848
6
established how Zommer provides any teaching or suggestion of
the implant dosage recited in appealed claim 1.
After reviewing the Zommer reference, we are in agreement
with Appellant’s position as stated in the Briefs, i.e. the
Examiner has not satisfied the burden of establishing how the
volumetric impurity concentration value set forth in atoms/cm3
in Zommer satisfies the claimed implant dosage requirement
expressed as an area value in atoms/cm . We are in particular2
agreement with Appellant’s contention that there is simply not
enough information in Zommer so as to enable a skilled artisan
to convert the disclosed volumetric impurity concentration value
to a specific implant dosage value. As pointed out by Appellant
(Reply Brief, page 2), an infinite number of implant dosage
values could result in the volumetric impurity concentration
expressed in Zommer; however, without specific diffusion
characteristic information such as depth and profile which is
lacking in Zommer, it is impossible to convert Zommer’s
concentration value to a specific implant dose as claimed. In
our view, any suggestion by the Examiner to assign
characteristics such as ion acceleration, peak concentration,
and annealing profiles from Appellant’s specification to the
Appeal No. 1999-2838
Application No. 08/812,848
7
disclosure of Zommer has no basis of support in Zommer and could
only come from an improper attempt to reconstruct Appellant’s
invention in hindsight.
As further alluded to by Appellant, it is apparent that the
Examiner has recognized the difficulty in attempting to convert
Zommer’s volumetric concentration value to a implant dosage
value and, instead, attempts to improperly convert Appellant’s
claimed dosage value into a volumetric impurity concentration
value. We agree with Appellant that the Examiner’s analysis at
pages 4 and 5 of the Answer is based on assumptions which have
no basis in the applied prior art. As pointed out by Appellant,
the transfer function equation from the Sze publication
referenced by the Examiner for converting impurity concentration
in atoms/cm to implant dosage in atoms/cm is based on a maximum3 2
impurity concentration value. We find no disclosure in Zommer
which characterizes the disclosed impurity concentration value
as a maximum or peak value. In order for us to sustain the
Examiner’s rejection under 35 U.S.C. § 103, we would need to
resort to speculation or unfounded assumptions or rationales to
supply deficiencies in the factual basis of the rejection before
us. In re Warner, 379 F.2d 1011, 1017, 154 USPQ 173, 178 (CCPA
Appeal No. 1999-2838
Application No. 08/812,848
8
1967), cert. denied, 389 U.S. 1057 (1968), rehearing denied, 390
U.S. 1000 (1968).
In view of the above discussion, it is our view that, since
all of the limitations of the appealed claims are not taught or
suggested by the prior art, the Examiner has not established a
prima facie case of obviousness. Accordingly, the 35 U.S.C. §
103 rejection of independent claims 1, as well as claims 2-14
dependent thereon, cannot be sustained. Therefore, the decision
of the Examiner rejecting claims 1-14 is reversed.
REVERSED

Appeal No. 1999-2838
Application No. 08/812,848
9

JOSEPH F. RUGGIERO )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
JOSEPH L. DIXON ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
LANCE LEONARD BARRY )
Administrative Patent Judge )
JFR/lp
Appeal No. 1999-2838
Application No. 08/812,848
10
OSTROLENK, FABER, GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK NY 10036-8403
Letty
JUDGE RUGGIERO
APPEAL NO. 1999-2838
APPLICATION NO. 08/812,848
APJ RUGGIERO
APJ BARRY
APJ DIXON
DECISION: REVERSED
PREPARED: Oct 9, 2002
OB/HD
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