Appeal No. 2002-0528
Application No. 09/524,519
representative claim 25, the sole independent claim on appeal,
reproduced below:
25. Field oxide isolation regions on the surface
of a silicon substrate with increased threshold
voltages and reduced leakage currents, comprised of:
a silicon substrate having field oxide formed by
local oxidation of silicon (LOCOS) resulting in
thinner portions on the perimeter of said field oxide,
said field oxide surrounding device areas on said
substrate;
said field oxide having sidewall portions formed
from an insulating layer that is conformally deposited
and anisotropically etched back to increase the
thickness of said thinner portions on said perimeter
of said field oxide;
channel-stop implant regions formed by implanting
a dopant through said field oxide and through said
sidewall portions formed from said insulating layer,
said channel-stop implant regions having a modified
implant profile resulting from said implanting of said
dopant through said sidewall portions thereby
increasing said threshold voltages and reducing said
leakage currents.
In addition to appellants’ admitted prior art (Figure 1 of
the present specification), the examiner relies on the following
prior art reference as evidence of unpatentability:
Liaw et al. 5,672,538 Sep. 30, 1997
(Liaw)
Claims 25 through 27 on appeal stand rejected under 35
U.S.C. § 103(a) as unpatentable over Liaw in view of the
appellants’ admitted prior art. (Examiner’s answer mailed Oct.
19, 2001, paper 13, pages 3-4.)
We reverse.
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