Appeal No. 96-1805
Application 08/200,432
suggested to one of ordinary skill in the art that the pressure
be reduced before the start of sticking, as is required in claims
1 and 13.
Another of the requirements in these two claims is that the
space between the wafers be filled with a gas having a viscosity
less than air before the start of sticking. We agree with the
examiner that one of ordinary skill in the art would have been
taught by Black that the bonding of silicon wafers can be
enhanced by doing the process in a hydrogen atmosphere. The
problem we find in the rejection is, however, a lack of
suggestion to combine in a manner which would meet the terms of
the claim. First of all, as we noted above, Hoshi teaches
eliminating the problem of gas bubbles remaining between the
bonded wafers by holding the wafers in a warped condition and
then releasing them to spring into contact with each other, this
being done in an environment of reduced pressure. However, as we
stated above, according to the record before us reduced pressure
is taught by Black as an alternative to the use of hydrogen gas.
This being the case, it is our view that Black would have taught
one of ordinary skill in the art to use either reduced pressure
or hydrogen gas, but not both together. Second, even
12
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