Appeal No. 1997-3162
Application 08/540,961
motivated to use the widened gate structure of Kikuchi if the
surrounding LOCOS isolation was replaced with shallow trench
isolation. For this reason, we conclude that the Examiner has
failed to establish a prima facie case of obviousness.
In addition, as to the second issue, we disagree with the
following statements by the Examiner (EA3): "Any inherent
threshold voltage, V , at the shallow trench edges is
t
obviously substantially equal to V between the shallow trench
t
edge. Note that 'substantially equal' does not mean 'equal'."
It is true that "substantially equal" does require exact
equality. Nevertheless, "substantially equal" is not without
meaning and does not imply that any two voltages will do. The
voltages must be approximately equal and we agree with
Appellants' argument (at RBr2) that the voltages must be
sufficiently close to meet the functional requirement of
avoiding the prior art leakage current problems or at least
minimize it to the point that it does not adversely affect
device performance. There is no evidence that applying the
gate structure of Kikuchi to a trench isolation structure
would "inherently" have the desired relationship. Kikuchi
does not disclose any relationship between the gate length and
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