Appeal No. 2003-1260 Page 11
Application No. 09/850,654
vias (Hsu, col. 1, ll. 44-47). Hsu also indicates that aluminum systems typically include copper
as an alloying metal to improve electromigration resistance (Hsu, col. 5, ll. 28-30).
Based on the evidence contained in Kimizuka and Hsu, we agree with the Examiner that
it would have been obvious to one of ordinary skill in the art at the time of the invention to use
an aluminum alloy in the via of Kimizuka. Hsu indicates that the two materials were known
alternatives for this use.
Appellants point out that Hsu fails to teach or suggest that the aluminum layer 520 has a
sidewall that extends from a barrier layer (Brief, p. 6). Hsu is focused on via filling and not on
the structures built atop the via. The fact that Hsu does not describe the additional structure does
not mean the structure is nonobvious: Kimizuka provides the required description of the
conductive structure and spacer arrangement above the via.
Appellants further argue that the replacement of the tungsten film 8 and the aluminum
film 9 with the aluminum layer 520 of Hsu would eliminate the purpose of the Kimizuka
reference that includes the sidewall silicon oxide insulating film 13 and the sidewalls of the
aluminum film 9 (Brief, p. 6). We fail to see how replacing tungsten with an aluminum alloy
eliminates the purpose of Kimizuka. The structure would still contain the filled via 8, conductive
structure 9 and insulating film 13. The purpose of Kimizuka is to provide insulating films 13 to
protect the conductive structure 9 and prevent charged particles from entering the conductive
materials and migrating to the gate oxide film 3 during plasma etching. That purpose, and thus
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