Appeal No. 1997-3360
Application No. 08/119,785
hydroxide” (Paper 23, examiner’s answer, page 4).
Nevertheless, the examiner has taken the following position:
Absent a showing of new or unobvious results, it
would have been obvious to clean wafers by
incorporating the step of washing the wafer in a
warm ultrasonically agitated aqueous detergent
solution of Cleveland to the dilute ammonium
hydroxide cleaning solution of Basi ‘954 or Basi
‘457 because not only will this stabilize the
properties of the semiconductor wafers as taught by
Cleveland, but also because each step is known
individually to improve the cleaning of wafers and
the person of ordinary skill in the art would expect
such combination to improve wafer cleaning in an
additive or cumulative manner. [Examiner’s answer,
p. 5.]
We disagree.
Both Basi ‘954 and Basi ‘457 teach the use of dilute NH OH
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to remove heavy metal ion contamination that may be present on
the polished surface of a semiconductor material following an
oxidizing operation (column 2, lines 43-54 of Basi ‘954;
column 2, lines 47-55 of Basi ‘457). According to these prior
art references, the oxidizing operation removes metal oxide
(e.g., silica) slurry particles, which are embedded in the
surface of the semiconductor during the polishing operation
and which evidently form siloxane-type bonds on the surface of
the semiconductor to render the surface to be hydrophobic
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