Appeal No. 2003-2097
Application No. 09/247,926 Page 7
Appellant asserts (reply brief, page 11) that one skilled in
the art would not have been motivated to combine the teachings of
the APA and Sandhu. Appellant argues (reply brief, page 14),
that Sandhu's suspension of the first etching process and the
addition of the etch stop layer 50 is to protect the silicide
layer at the top elevation. It is further argued (reply brief,
page 15) that in the APA, the second etching process is performed
to remove the silicide layer 45 of word line 4b. This same
etching process removes a portion of source/drain region 5a.
In Sandhu, the etch stop prevents the silicide layer from
being removed. It is further argued (reply brief, pages 15-17)
that because Sandhu is protecting the silicide layer, the etching
is stopped to protect the silicide layer and not to prevent the
source/drains from being damaged. Appellant further argues
(reply brief, page 19) that the APA intentionally removes the
silicide layer to decrease the resistance in the contact hole 8a.
In contrast, Sandhu suspends the etching process and adds the
etch stop layer 50 to prevent the removal of the silicide layer
45. If Sandhu were somehow combined with the APA, after the
etching to the silicide layer was reached, an etch stop would be
formed on layer 45. As a result, when the etching continued to
expose the source/drain regions, none of the silicide layer would
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