Appeal No. 2003-0512
Application 09/184,805
deposited tungsten layer, and a tungsten layer 309. Cadien’s
method comprises polishing the tungsten layer 309 with a first
slurry (column 6, line 36 to column 8, line 43), polishing the
titanium nitrate adhesion layer 306 with a second slurry (column
8, lines 43 to 66), and polishing the titanium contact layer 305
with a third slurry (column 8, line 67 to column 9, line 52).
The resulting polished substrate is illustrated in Fig. 3d.
Central to Cadien is the utilization of a specifically engineered
slurry for polishing each of the layers 308, 306 and 305.
In rejecting the appealed claims, the examiner found, and
appellants did not dispute, that Cadien discloses polishing the
filler layer 308 of a substrate with a first slurry and a second
slurry, wherein the slurries have different selectivities.1 The
examiner concedes that Cadien does not disclose polishing the
filler layer with the first slurry until the stop layer is
partially covered and partially exposed, and then polishing the
filler layer with the second slurry until the stop layer is
substantially exposed, as called for in the claims. The examiner
1 In accordance with appellants’ specification, the
“selectivity” of a slurry as used in the appealed claims refers
to the ratio of the polishing rate of the filler layer to the
polishing rate of the stop layer. Specification, page 8, lines
29-33.
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