Appeal No. 94-1889
Application 07/890,003
portions which lie on and project outwardly from opposite
surfaces of a transparent substrate.
Rejection over Okamoto in view of Levenson
Okamoto discloses various masks having phase-shifting
portions which project outwardly from one surface of a
transparent substrate (see, e.g., Figs. 1, 4 and 14). Okamoto
does not disclose phase-shifting portions on more than one side
of the substrate.
To remedy this deficiency, the examiner relies upon
Levenson. This reference discloses a mask having phase-shifting
portions and teaches that A[t]he transparent material [i.e.,
phase-shifting portions] may be either over or under every other
transmitting region of the mask@ (sixth page).
The examiner argues (answer, page 3):
Levenson teaches that the phase shifting portion may be
on either side of the substrate. Okamoto or Levenson
do not teach phase shifting portions on both sides of
the substrate. It would have been obvious to one of
ordinary skill in the art to produce phase shifters on
both sides of the substrate because of the suggestion
of Levenson to put shifters on either side of the
substrate and because of the expected and predictable
results of the optical properties of such phase
shifting masks.
Appellant argues that Levenson discloses that the phase-
shifting material is either over or under every other
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