Appeal No. 95-5041
Application No. 08/163,967
a second field shield plate disposed on said second layer
of insulating material, directly above and in electrical
contact with said first impurity region, and having an outer
edge terminating directly above said substrate beyond said
junction extension so that said junction extension is
positioned on said major surface between the outer edge of
said first field shield plate and the outer edge of said
second field shield plate.
The reference relied on by the examiner is:
Terashima 5,204,545 Apr.
20, 1993
Claims 1, 4 and 5 stand rejected under 35 U.S.C. § 103 as
being unpatentable over the admitted prior art in Figures 2A
and 3A in view of Terashima. According to the examiner
(Answer, page 4):
Appellant’s prior art figures 2A and 3A disclose
all the claimed subject matter except for the first
field shield plate having an outer edge terminating
before the PN junction. However, Terashima teaches
from line 38 of column 2 that it is “possible to
prevent concentration of electric fields caused in
the end region 7a of the island 7" by applying
electric fields from interconnection 15 (equivalent
to layer 34 in figure[s] 2A to 3B of Appellant’s
drawings) with a fixed potential[s] (note line 31 of
column 2) at plates 16b, 16c, and 16d (equivalent to
layer 30 in figure[s] 2A to 3B of Appellant’s
drawings) so that “the equipotential lines in the
depletion layers are not concentrated toward the p-
type isolating diffusion region 13" (note line 43 of
column 2) to increase “breakdown voltage” (note line
49 of column 2). Therefore, it would have been
obvious to one of ordinary skill in the art to form
the first field shield plate 30 in Appellant’[s]
5
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