Appeal No. 2003-2097
Application No. 09/247,926 Page 8
have been removed. Appellant adds (reply brief, page 20) that
“not removing the portion of the silicide layer 45 that is
exposed via the contact hole 8a contradicts the APA’s express
purpose of reducing the resistance in the contact hole 8a. In
fact, adding the etch stop layer 50 would actually increase the
resistance in the contact hole 8a.”
From our review of the APA and Sandhu, we find that the APA
(figure 1b) teaches removal of the silicide layer 4b at the
bottom of contact hole 8a. In Sandhu, it is disclosed that the
etching stops at the high elevation conductive region outer
surface 36 (col. 4, lines 62-65). Sandhu further discloses
(col. 5, lines 2-5) selectively depositing an etch stop layer
atop the outer surface 36 of the high elevation conductive
region.
From the disclosures of APA and Sandhu, we find that APA
teaches removing the silicide layer, whereas Sandhu teaches
preventing removal of the silicide layer. Because APA teaches
removing the silicide layer and Sandhu teaches keeping the
silicide layer, we find that an artisan would not have been
motivated to have combined the teachings of APA and Sandhu to
arrive at the claimed invention, as advanced by the examiner.
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