Appeal No. 94-2080
Application 07/982,068
of the finger-like mesas relative to any specific crystal lattice
plane, or the orientation of the principal plane. That
deficiency is recognized by both the appellants and the examiner.
Castrucci, on the other hand, discloses a conventional non-
vertical transistor structure formed with a (100) oriented
principal substrate plane. But the appellants are correct that
even if the teachings of Wickstrom and Castrucci are reasonably
combinable, which we think it is, it only would reasonably have
suggested using the (100) crystal plane as the principal plane.
The appellants have advanced no reason why the same principal
plane orientation used for conventional non-vertical transistor
structures may not be used for vertical transistor structures.
Assuming that the principal substrate surface plane is the
(100) plane in Wickstrom, there are still many possible
orientations for the side walls of the finger-like mesas, not
necessarily aligned with the (010) or (001) crystal plane, or
with a plane at 45E angle to the (01ù) plane, as is required by
the appellants’ claims. On this record, the examiner has not
presented sufficient evidence that one with ordinary skill in the
art would have deemed obvious to orient the finger-like mesas of
Wickstrom in a direction such that their side walls are aligned
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