Appeal No. 1998-2671
Application No. 08/480,543
deposition of aluminum 34 over a refractory metal 32 to fill
apertures 24a-24e in insulator layer 22. As recognized by the
Examiner, Schilling is silent as to any disclosure of aluminum
deposition rate or temperature. To address this deficiency, the
Examiner turns to Tracy which provides a two-step aluminum
deposition process, the second step including deposition at a
temperature of 400°-500° C, to ensure complete coverage of the
deposited metal in a via or contact hole. In the Examiner’s line
of reasoning (Answer, page 6) the skilled artisan would have been
motivated and found it obvious to deposit the aluminum in
Schilling at the temperature suggested by Tracy, i.e. 400°-500°
C, in order to provide full metallization coverage in the contact
opening. The Examiner further asserts that, from the evidence of
record including statements at pages 8 and 9 of Appellants’
specification, the deposition of aluminum at the 400°-500° C
temperature range suggested by Tracy would necessarily form an
alloy with the underlying refractory metal layer.
Appellants’ arguments in response can be summarized from the
following statements from page 11 of the Brief:
Nothing in either reference suggests the use of
high temperature deposition over enough refractory
metal to substantially fill the opening with alloy.
Although the combination of previously
separately known steps, in accordance with the
9
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