Appeal No. 2000-1587
Application 09/055,254
partial etch back as well as the following curing step to
convert the remaining SOG to a protection mask (brief, page 5
and reply brief, page 2).
In response to Appellants’ arguments, the Examiner argues
that “Zheng forms the SOG, partially etches it, and then
further etches by CMP” whereas Wolf “describes conventional
practice for baking/setting [the] SOG and then baking/curing
[it] at a higher temperature” (answer, page 7). The Examiner
concludes that Zheng, although silent on curing, “could not
complete the CMP step without the conventional practice of
baking and curing [of the SOG]” (answer, page 7). With
respect to the relative etch rate of oxide and SOG, the
Examiner asserts that criticality of this feature was not
indicated by Appellants and therefore, any small deviation
from the selectivity of 1:1 is routine optimization and meets
the claimed limitation (answer, page 8).
Initially, we note that the Examiner indicates the
following features as missing in Zheng: how the silicon oxide
and silicon nitride layers of the hard mask are formed; the
high temperature cure of the SOG and specifying a range for
7
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