Appeal No. 1997-3691 Page 6
Application No. 08/298,018
sheet resistance of the gate without increasing the junction depth of source/drain regions (42). Similarly,
we find that Sitaram utilizes a disposable structure (20) over the gate to prevent (col. 4, lines 41-43) the
gate (18) from being silicided (figure 3) at the same time as the areas (26) over the source/drain.
Sitaram teaches (col. 5, lines 46-53) that “[i]t is important to note that the silicided regions 26 and the
silicided region 30 are formed via different metal materials” because
“[a]s stated previously, there are disadvantages to forming all of the
electrodes (i.e. gate, source, and drain) with a single type of silicide
region. . . . for example . . . cobalt silicide is not an optimum gate electrode
silicide but is a good silicide region for both sources and drains when compared
to other silicides.” (col. 5, lines 55-68)
As to the specific question of "teaching away," our reviewing court in In re Gurley, 27 F.3d 551, 553,
31 USPQ2d 1130, 1131 (Fed. Cir. 1994) stated:
[a] reference may be said to teach away when a person of ordinary skill, upon [examining] the
reference, would be discouraged from following the path set out in the reference, or would be
led in a direction divergent from the path that was taken by the applicant.
We are in agreement with appellant (brief, page 6) that both Rodder and Sitaram use their disposable
structures to prevent simultaneously forming silicide regions on both the gate structure and the
source/drain regions in order to have silicide regions of different thickness or materials. We therefore
find that one of ordinary skill in the art would have been taught away from providing Feist with a
disposable structure in view of Feist’s disclosure of forming the silicide layers over the gate structure
and the source/drain regions at the same time.
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