Appeal No. 1998-0970
Application 07/995,325
and (3) the specific process step of depositing the boron
impurity as recited in step h).
As to difference (1), it is implied by the rejection that
it would have been obvious to apply the same natural oxide
layer removal step to the impurity diffusion region 113. This
difference is not argued and, thus, will not be addressed.
As to difference (2), the Examiner finds that Nickl
discloses removal of native oxide using etching agents at
900-1300EC and that Allman discloses removal of native oxide
by reaction with HCl or H gas at 800-900EC (EA4). The
2
rejection implicitly concludes that it would have been obvious
to use the native oxide removal processes of Nickl or Allman
in place of the native removal method in Tsunashima.
Appellants argue that Tsunashima does not discloses any
temperatures for the surface cleaning processes, but the two
processes (etching with dilute fluoric acid or by argon
sputtering in a vacuum) can typically be carried out at low
temperature and even room temperature (Br6). It is argued
that one skilled in the art would have no reason to combine
the teachings of Nickl with Tsunashima in any particular
manner because Tsunashima discloses removal of the natural
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