Appeal No. 1999-2347
Application 08/892,560
understanding of the term, i.e., "insofar as what constitutes
such an etching can be determined or deciphered" (FR9).
Appellants argue (Br7) that the specification discusses low
selective etching on page 5, lines 19-21, stating "the via may be
formed by first using a low selective (oxide to nitride) standard
etch down to a point just above the nitride layer."
While this provides written description support for the
limitation, it does not define what is meant by "low." We note
that Appellants tried to amend the specification to define that
"[a] 'low selective' etch means an etch having an oxide etch rate
which is less than 10 times its nitride etch rate"
(amendment filed August 9, 1995, Paper No. 5). The Examiner
objected to the addition as new matter (Paper No. 6, p. 2) and
the amendment was canceled.
Appellants next argue that the selectivity in etching
silicon oxide and silicon nitride, as well as anisotropic
etching, is well defined in U.S. Patent 5,286,344 to Blalock
et al. (Blalock) which is incorporated by reference on page 8 of
the specification (Br7-8).
Instead on pointing out what part of Blalock defines what is
meant by "low selective etch," Appellants leave it to us to
figure out. This is not the type of argument calculated to
persuade us of error. Blalock is not directed to the etch steps
of claim 27. Nevertheless, claim 13 of Blalock recites a "high"
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