Appeal No. 95-0589
Application 07/873,150
portion, the reference does not disclose the claimed method for
obtaining the mask. However, the examiner concludes "[i]t would
have been obvious to one of ordinary skill in the art to use any
art-recognized mask manufacturing method to produce sub-space
regions because of the expected results of such resist exposure
and etching methods being used to produce a known phase-shifting
mask" (page 3 of Answer, emphasis added).
The fundamental error in the examiner's rejection is that no
factual evidence is relied upon to establish the obviousness of
the specifically claimed method steps. Undoubtedly, each of the
claimed steps, individually, was known in the photolithographic
arts at the time of filing the present invention. However, that
each individual step was known is not sufficient to establish a
prima facie case of obviousness for the particularly claimed
manipulative steps of forming a phase-shifting mask. Stated
otherwise, the examiner has presented no evidence that it was
known in the art to manufacture a phase-shifting mask by the
claimed photolithographic steps. For instance, the processes
disclosed by Okamoto and the Nitayama publication for forming
phase-shifting masks are different than the claimed method,
although they include known photolithographic steps.
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