Appeal No. 1998-3401
Application No. 08/495,277
Kumar's teaching that the conductive material may be planarized
by chemical-mechanical polishing or wet etching. (Column 3,
lines 39-46.)
Realizing that Kumar does not describe step (e) as recited
in the appealed claims, the examiner relies on the teachings of
Dull to account for this difference. Regarding Dull, the
examiner states:
Dull discloses that cupric chloride is a known etchant
for copper (claim 1), and that such a composition
provides for a slow etch rate in order to precisely
form close tolerances (col. 2, lines 48-52). The
etchant of Dull is the same as that used by applicants
as their "low-reactive solution" and thus is expected
to behave similarly, i.e., form a film barrier that
substantially inhibits further removal of the
conductive material. [Examiner's answer, p. 4.]
The examiner then concludes:
It would have been obvious to use the etchant of Dull
in a method similar to Kumar et al because Dull teaches
that it provides for a slow etch rate that gives close
tolerances...The method of the combination of Kumar et
al and Dull inherently initially removes a surface
portion of the conductive material and forms a film
barrier that inhibits any further removal of the
conductive material because the same etchant and
process steps are used. It would have been obvious to
one with ordinary skill in the art to disrupt the film
barrier to thereby stimulate removal of additional
surface portion and formation of additional barrier
solution until the desired height is achieved in the
modified method of Kumar et al in order to make the
etching process effective. [Id.]
In responding to the appellants' argument (e.g., appeal
thereby stimulating removal of additional surface portions and
formation of additional film barrier."
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