Appeal No. 2001-0776
Application 09/276,043
Appellants argue that claim 1 requires, among other steps,
the steps of forming a thin layer of silicon over the underlying
layer wherein the silicon layer has a thickness less than 5 nm,
and then nitriding this thin layer of silicon to form silicon
nitride layer less than the tunneling thickness of the silicon
nitride layer, as part of the process of adhering tungsten to an
underlying layer (brief, page 3). On page 4 of the brief,
appellants also argue that Contreras has nothing whatsoever to do
with the problem of adhesion, and therefore any combination with
Contreras is improper.
Firstly, we note that the reason or motivation provided in
the prior art does not have to be the same as that of the
applicants to establish obviousness. See In re Kemps, 97 F.3d
1427, 1430, 40 USPQ2d 1309, 1311 (Fed. Cir. 1996). Hence, we
disagree with appellants’ position that the combination is
improper because Contreras “has nothing whatsoever to do with the
problem of adhesion”.
With regard to the teaching of the tunneling thickness
recited in step (c), we find that Suehiro teaches that to prevent
the reaction of tungsten with silicon, a reaction inhibiting film
may be interposed between a polycrystalline silicon layer and a
refractory metal layer. Suehiro refers to a Kokai publication as
an example for disclosing that a silicon nitride film effectively
prevents a molybdenum layer from reacting with a polycrystalline
layer. Suehiro indicates that this publication teaches that the
silicon nitride film should desirably have a thickness ranging
from 1 nm to 5 nm in order to allow a tunnel current to flow
between the molybdenum layer and the polycrystalline silicon
layer. See column 2, lines 12-22. Hence, we agree with the
examiner that Suehiro teaches the aspect of forming a silicon
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