Appeal No. 1999-2683
Application 08/754,564
used as an etch stop layer because it was well known that the
overlying SOG is softer and has a higher etching rate than
silicon oxide. The Examiner finds that Tsu suggests (at
col. 3, element 24 in Table 1) that other dielectric materials
can be substituted for layer 24. The Examiner concludes that
it would have been obvious to substitute a silicon nitride
etch stop layer as taught by Kalnitsky for the silicon oxide
layer 24 in Tsu "because the silicon nitride layer also has
lower etching rate than the SOG layer, and because it could be
used as an etch stop layer to protect damaging interaction
with chemicals associated with subsequent process steps, such
as explicitly taught by Kalnitsky (column 2, lines 14-19)"
(Final Rejection, p. 4). The Examiner finds that neither Tsu
nor Kalnitsky discloses a plurality of substantially parallel,
separated, patterned metal layers, but finds that such
limitation is taught in the APA of Appellant's figure 1 and
concludes that it would have been obvious to construct a
plurality of layers in Tsu in view of the APA (Final
Rejection, p. 4). The Examiner interprets independent
claim 26 as a product-by-process claim and impliedly concludes
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