Appeal No. 2000-1587
Application 09/055,254
its low temperature baking and the use of ion etching and
selectively etching of oxide in relation to that of spin on
glass. Among the above-noted features, only curing of the SOG
and selectively etching of oxide in relation to that of spin
on glass are recited in claim 1, the only independent claim.
To simplify the analysis, we initially focus our evaluation of
the prior art and claim 1 on these two features.
After a review of Zheng, we find that the reference
relates to a process for forming planarized shallow trench
isolation in integrated circuits (col. 1, lines 41-43). As
the Examiner and Appellants concede, Zheng teaches forming a
hard mask over a substrate (Fig. 1 and col. 2, lines 26-30),
etching shallow trenches in the substrate (Fig. 2 and Col. 2,
lines 37-42) and forming an oxide layer (Fig. 3 and col. 2,
lines 43-59). Zheng further teaches coating a layer of SOG
(Fig. 4 and col. 2, lines 64-66, col. 3, lines 4 and 5),
etching back of SOG and oxide layers (Fig. 5 and col. 3, lines
16-21) and etching back the remaining oxide and SOG layers as
well as the hard mask (Fig. 6 and col. 3, lines 22-32). Zheng
clearly requires identical etch selectivity for both the oxide
and the SOG layers where the remaining oxide and SOG layers
8
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