Appeal No. 2002-1992
Application 09/206,170
Rejection of claims 2, 5, 10, 15 and 16 under 35 U.S.C. § 103
over Chen in view of Grieger and Schonauer ‘769
Schonauer ‘769 discloses a method for cleaning metal
compound contaminants remaining at or in the surface of a
semiconductor wafer following chemical mechanical polishing, by
etching away a 30-50Å layer of oxides from the wafer surface
(col. 1, lines 46-57; col. 6, lines 12-21). Schonauer ‘769
postulates that when the polishing slurry oxidizing agent is an
iron compound, due to the abrasive nature of the chemical
mechanical polishing process, some fraction of the slurry iron
which contacts the wafer becomes physically buried beneath the
surface of the oxides, and is not removed by post-chemical
mechanical polishing cleaning agents that contact the liquid-
solid interface (col. 2, lines 14-19; col. 3, lines 25-29).
Schonauer ‘769, therefore, uses a cleaning solution containing HF
and a chemical complexing agent to etch away a very shallow depth
of the polished surface while simultaneously complexing the Fe
impurity and other metal impurities (col. 3, lines 30-38).
The examiner argues that “[i]t would have been obvious to
one of ordinary skill in the art to wash the substrate for the
time periods and removal thickness set forth by Schonauer [sic]
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