Appeal No. 2001-1133 5
Application No. 09/014,806
The Rejection under § 103
"[T]he examiner bears the initial burden, on review of the prior art or on any other
ground, of presenting a prima facie case of unpatentability." See In re Oetiker, 977 F.2d
1443, 1445, 24 USPQ2d 1443, 1444 (Fed. Cir. 1992). The examiner relies upon a
single reference to reject the claimed subject matter and establish a prima facie case of
obviousness. It is the examiner’s position that, although, “Kadomura is silent as to using
diatomic oxygen,” nonetheless, “it would have been obvious to those of ordinary skill in
the art to include O2 in the etchant gas mixture because it is well known as oxidizing gas
and because combining materials or additives for their art recognized function and said
additives do perform their art recognized function is obvious.” See Answer, pages 6 and
7. We disagree.
Kadomura is directed to a dry etching method wherein silicon nitride existing on a
substrate of silicon dioxide can be etched at a sufficiently high selective ratio between the
nitride and the oxide without providing deposition of polymeric film. See column 2, lines
47-53. Furthermore, we agree with the examiner’s finding that, “Kadomura is silent as to
using diatomic oxygen.” See Answer, page 6. The entire issue of a teaching or suggestion
for the utilization of oxygen is a result of the background disclosure present in the
Kadomura patent. We find that Kadomura states in the background of the invention that,
the etch rate of Si3N4 becomes higher when the etching gas
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