Appeal No. 1997-4024
Application No. 08/299,407
process, but such an etching process makes it difficult to
remove the polysilicon layer evenly across its surface
"because the area within the contact holes can easily become
overetched due to the microloading effect" (page 3 of
principal brief). According to appellants:
The present invention solves the problem of
overetching and resulting convex and concave
portions of the interlayer insulating film by
employing not a dry etching process, but rather a
chemical and mechanical polishing process using
piperazine or colloidal silica slurry to flatten the
polysilicon layer 3 or secondary interlayer
insulating film 7 [page 4 of principal brief].
Appealed claims 1-8 stand rejected under 35 U.S.C. § 103
as being unpatentable over Yamamichi.
Upon careful consideration of the opposing arguments
presented on appeal, we concur with appellants that the
examiner has failed to establish a prima facie case of
obviousness for the claimed subject matter. Accordingly, we
will not sustain the examiner's rejection.
The examiner concedes that Yamamichi "fails to teach
flattening the surface of the polysilicon layer by chemical or
mechanical polishing by piperazine or colloidal silica slurry"
(page 4 of Answer). Hence, the single reference applied by
the examiner fails to teach or suggest the essence of
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