Ex parte BAUKUS et al.

Board of Patent Appeals and Interferences

Feb 26, 1998

08191063 (B.P.A.I. Feb. 26, 1998)

THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered today
(1) was not written for publication in a law journal and
(2) is not binding precedent of the Board.
Paper No. 31
UNITED STATES PATENT AND TRADEMARK OFFICE
_______________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_______________
Ex parte JAMES P. BAUKUS,
WILLIAM M. CLARK, JR., LAP-WAI CHOW,
and ALLAN R. KRAMER
_______________
Appeal No. 95-3779
Application 08/191,0631
_______________
ON BRIEF
_______________
Before THOMAS, HAIRSTON, and KRASS, Administrative Patent Judges.
KRASS, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal from the final rejection of
claims 1 through 15 and 21. Claims 22 and 23 stand withdrawn as
being directed to a nonelected invention.
The invention is directed to an integrated circuit security
system for preventing reverse engineering of an integrated
circuit. More particularly, multiple logic circuits are provided

1 Application for patent filed February 3, 1994. According to
appellants, this application is a continuation of Application
07/923,411, filed July 31, 1992.
Appeal No. 95-3779
Application No. 08/191,063
2
which have discernible layouts, which look alike to a reverse
engineer, but with dopant implant interconnections that are not
discernible by reverse engineering.
Representative independent claim 1 is reproduced as follows:
1. A secure integrated circuit (IC), comprising:
a semiconductor substrate,
at least two logic circuits of different types formed in
said substrate with layouts which make said two logic circuits
look alike to a reverse engineer, each logic circuit having doped
IC elements, and
an interconnect for at least one of said elements, said
interconnect comprising a dopant implant in said substrate of
like conductivity to said element, and providing an electrical
signal path to interconnect said element with another portion of
the IC, said dopant implant being substantially not discernible
by reverse engineering techniques.
The examiner relies on the following references:
Koeppe 4,799,096 Jan. 17, 1989
Kuwana 5,138,197 Aug. 11, 1992
(filed May 22, 1991)
Sawase (JP) 58-190064 Nov. 5, 1983
Claims 1 through 15 and 21 stand rejected under 35 U.S.C.
' 112, first paragraph, under the written description provision
of that statutory section as being based on a specification that
allegedly fails to provide support for the invention as is now
claimed.
Claims 1 through 15 and 21 also stand rejected under
35 U.S.C. ' 103 as unpatentable over Kuwana.
Appeal No. 95-3779
Application No. 08/191,063
3
Moreover, claims 1 through 15 and 21 stand further rejected
under 35 U.S.C. ' 103 with Koeppe being relied upon for evidence
of the obviousness of claims 1 through 4, 6 through 13, 15 and
21, the examiner adding Sawase with regard to claims 5 and 14.
Rather than reiterate the positions of appellants and the
examiner, reference is made to the briefs and answer for the
respective details thereof.
OPINION
We turn first to the rejection based on the written
description portion of 35 U.S.C. ' 112. The examiner takes the
position that none of the original structures look alike because
the specification states that the structures “may be made to look
alike” [page 4-line 34-35] and this is not a statement of
certainty. The examiner then points to connections 20, 22, 32
and 36 in Figures 1b, 2b and 5, stating that they do not look
alike and concludes that since the claims require the two
circuits to look alike, there must be a lack of support for this
subject matter in the claims.
The examiner’s position is misplaced. While the examiner is
correct in the assessment that the connections in the various
figures of the drawing do not look alike, this is a crucial part
of the invention. As described throughout the specification, the
layouts of the logic circuits do look alike to the reverse
engineer. It is the dopant implant interconnections which do not
Appeal No. 95-3779
Application No. 08/191,063
4
look alike but are not discernible by the reverse engineer.
Thus, the invention, as claimed, has clear support in the instant
disclosure.
We will not sustain the rejection of claims 1 through 15 and
21 under 35 U.S.C. ' 112, first paragraph.
Turning now to the rejections under 35 U.S.C. ' 103, we also
will not sustain these rejections. The examiner relies on
Figures 5 and 6 of Koeppe and on Figures 4 and 8 of Kuwana and
contends that the two figures, representative of logic circuits,
in each reference show layouts of different types of logic
circuits which “look alike” along with dopant implant
interconnections which are obviously not discernible by reverse
engineering.
Appellants do not deny, and, in fact, with respect to
Koeppe, admit [at page 5 of the principal brief], that the
principal references employ implanted interconnects that would
not be discernible to a reverse engineer. However, independent
claims 1 and 7 also require, with respect to claim 1, that the
logic circuits have “layouts which make said two logic circuits
look alike to a reverse engineer” and, with respect to claim 7,
that the logic gate have “a layout which makes it look like
another kind of logic gate.”
Notwithstanding any position of the examiner to the
contrary, we simply do not find the circuit layouts in Figures 5
Appeal No. 95-3779
Application No. 08/191,063
5
and 6 of Koeppe to “look alike” nor do we find the circuit
layouts of Figures 4 and 8 of Kuwana to “look alike” as required
by the instant claims. The circuit arrangement of Koeppe’s
Figure 5, depicting three parallel circuit branches is clearly
quite different looking than Figure 6 of that reference depicting
a circuit arrangement having four parallel circuit branches.
Similarly, the NAND-gate layout in Figure 8 of Kuwana is quite
clearly different looking than the circuit layout shown in Figure
4 of Kuwana.
The Sawase reference, applied against dependent claims 5 and
14 in combination with Koeppe, does not provide for the
deficiencies noted supra with regard to Koeppe.
Accordingly, since neither Koeppe nor Kuwana discloses or
suggests the multiple different logic circuits having discernible
layouts which look alike, but dopant implant interconnections not
discernible by reverse engineering, as claimed, the examiner’s
rejection of the claims under 35 U.S.C. ' 103 is reversed.
We have reversed both the rejection of the claims under
Appeal No. 95-3779
Application No. 08/191,063
6
35 U.S.C. ' 112, first paragraph, and the rejection of the claims
under 35 U.S.C. ' 103. Accordingly, the examiner’s decision is
reversed.
REVERSED
James D. Thomas )
Administrative Patent Judge )
)
)
)
Kenneth W. Hairston ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
Errol A. Krass )
Administrative Patent Judge )
Appeal No. 95-3779
Application No. 08/191,063
7
S.E. Walters
Hughes Electronics
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