Appeal No. 2000-1112
Application No. 08/518,363
"describes phase shift masks as being an inchoate, developing
technology that may or may not prove useful. The cover page
questions whether phase sift [sic] technology can improve
lithography performance or whether the inspection and repair
demands of phase shift technology will prevent it from being
useful." Appellant also points to Burggraaf's indication that
phase shift technology "does not improve the accuracy of all
existing steppers." Appellant concludes (Brief, page 8) that the
above-noted teachings of the two references would have led the
skilled artisan away from the examiner's proposed combination.
We disagree with appellant. Muraki does expressly consider
the merits of a phase shifting mask, but rejects them for the
particular application contemplated in that patent. Muraki
actually indicates that phase shift masks improve resolution
(column 1, lines 51-54), however under certain circumstances, it
is difficult (though not necessarily impossible) to use a phase
shift mask (column 2, lines 1-20). Thus, Muraki teaches that
phase shift masks are beneficial, but also have drawbacks. That
means one of ordinary skill would have to weigh the benefits
against the drawbacks for any particular application; it is not a
teaching away as indicated by appellant.
Similarly, Burggraaf teaches that a phase-shift reticle has
the benefit of increasing image contrast and resolution, but the
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