Appeal No. 1997-3338
Application No. 08/402,252
substrate. According to the appellants (appeal brief, page
2), the contact openings are etched in the dielectric layer
down to the doped regions in a semiconductor (e.g.,
polysilicon or doped regions in a semiconductor substrate)
which have a titanium silicide layer on top. A rapid thermal
anneal of at least about 600EC in a nitrogen-containing
atmosphere comprising the recited nitrogen-containing species
is used to convert the top portion of the titanium silicide
layer into a barrier titanium nitride layer. Next, the
recited metal layer is deposited by high temperature metal
sputtering, regular metal sputtering followed by high
temperature reflow, or chemical vapor deposition. Then a
metal plug is formed in each contact opening by chemical-
mechanical polishing or plasma etchback.
As evidence of unpatentability, the examiner relies upon
the following prior art references:
Koyanagi et al. (Koyanagi) 4,701,349 Oct. 20,
1987
Scovell et al. (Scovell) 4,772,571 Sep.
20, 1988
Sun et al. (Sun) 4,994,410 Feb. 19,
1991
Sandhu et al. (Sandhu) 5,124,780 Jun. 23,
1992
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