Appeal No. 2001-2444
Application No. 09/419,176
disclosed etch stop materials include silicon nitride (col. 4,
lines 9-13).
The portion of Chiang relied upon by the examiner discloses
both silicon nitride and silicon carbide as etch stop materials
(col. 14, line 66 - col. 15, line 5).
The examiner argues (office action mailed September 1, 2000,
paper no. 6, page 3):
It would have been obvious to one having ordinary
skill in the art at the time of the claimed invention
to modify Fiordalice et al. by replacing SiN with SiC
as taught by Chiang et al. because the SiN and SiC are
seen as equivalent: they are dielectric, etch stop
materials if they are used in an etching process and
planarizing stop materials if they are used in a
planarizing process, hence the substitution of one for
the other would have been anticipated to produce an
expected result.
Fiordalice, however, does not disclose silicon nitride as a
planarization stop but, rather discloses it only as an etch stop.
Since the planarizing takes place above dielectric layer 30 as
shown in Fiordalice’s figure 7, the etch stop, which is below
dielectric layer 30, cannot serve as a planarization stop.
Hence, even if Chiang’s silicon carbide were substituted for
Fiordalice’s silicon nitride etch stop material as proposed by
the examiner, the appellants’ claimed invention would not be
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