Appeal No. 95-3455
Application 07/945,902
used dichlorosilane instead of silane to reduce tungsten
hexafluoride, motivated by the various advantages described by
the art on which we rely. We also are satisfied because of
the well-known chemistry involved in reducing tungsten
hexafluoride with silanes, in general, that being so-motivated
the person of ordinary skill would have expected to succeed in
obtaining a tungsten silicide layer useful in the manufacture
of various semiconductor devices, including floating gate
electrodes.
With respect to the limitations of dependent claims 3, 5
and 7, we find that: Hillman in the examples and at column 4,
lines 27 through 39; Price'343 at column 9, lines 5 through
16; Price'474 at column 3, lines 44 through 49; and Koyama et
al. in their disclosure that higher temperatures are employed
for reducing tungsten hexafluoride with dichlorosilane than
with silane establish the reaction parameters and conditions
claimed are well-known process variables in the CVD of
tungsten silicide. Accordingly, the adjustment and selection
of these variables would have been within the ordinary skill
of a person in this art.
OTHER ISSUES
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