Appeal No. 95-3438
Application No. 08/033,656
ordinarily it may be the case that the determination of
optimum values for a result effective parameter of a prior art
process is at least prima facie obvious, that conclusion
depends upon what the prior art specifically discloses with
respect to that parameter. In re Sebek, 465 F.2d 904, 906,
175 USPQ 93, 95 (CCPA 1972). Although Morosanu teaches that
LPCVD processes, in general, have been carried out in the
broad pressure range of 0.1-100 Torr, the more specific
teachings in Chiang and Sakai direct one of ordinary skill in
the art to a much lower pressure range than claimed for
producing silicon nitride films having adequate thickness
uniformity.
The examiner correctly notes that Schuegraf teaches that
processes utilizing single wafer reactors for LPCVD processing
provide for high deposition rates and exceptionally high
uniformity. However, the examiner has not adequately and
persuasively explained why one would have been led to operate
such a single wafer reactor process within a pressure range as
claimed for producing a silicon nitride coating. As
appellants point out, single wafer reactors are used primarily
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