Appeal No. 2000-0170
Application No. 08/811,124
layer with no Si component absorbs Si atoms from the metal with
the Si component . . . .’ The particulars . . . are entirely
absent from the disclosure of Lee.”
The examiner responds (answer at page 10) that
[in reference to Fig. 5 of Lee] the plug 25 and the
metallization line 27 are electrically connected, and
wherein the surface of the metallization line 27 is
planarized by heat-treated in the same manner as first
metal layer . . . . Accordingly, after heat treated,
the first metal and the second metal react to each
other, and the metal layer with no Si component absorbs
Si atoms from the metal with the Si component to form a
composite metal layer . . . . In other words, because
of the silicon diffusion from one metal layer to
another metal layer during heat treatment, the
diffusional equilibrium is inherently formed between
the contacting surface of the first metal and the
second metal.
Appellants respond (reply brief at page 2) that
“[d]iffusional equilibrium requires two phases that are miscible
and have fully intermingled. In other words, no composition
gradient is possible. Anticipation is therefore not present [in
Lee].”
After review of the two positions, we are of the view that
because of the diffusion of Si atoms from one metal to the other
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