Appeal No. 96-0289
Application 07/935,301
to diffuse into the metallic wiring layer to form a solid solution, and when the polysilicon is cooled,
crystals are deposited, thereby forming the silicon nodule and producing a constriction in the metallic
wiring layer above the nodule (page 5). When electric current further is passed through the metallic
wiring layer, the metallic wiring layer at the constricted portion is melted (pages 5-6).
Appellants argue that Fujita teaches that the polysilicon is diffused into the metal, which is
directly in contrast to appellants’ claimed method wherein metal is absorbed into polysilicon (brief,
pages 6 and 10). We do not find this argument to be convincing because Fujita teaches (page 5) that
after the polysilicon diffuses into the metal and forms a solid solution with it, the polysilicon is cooled
and forms crystals which are deposited as nodule 15 on polysilicon layer 12. Since the nodule is
formed by precipitation of polysilicon from a solid solution, it appears that the
nodule comprises polysilicon which is available for absorption of metal when the current is passed
through the metal to blow the fuse.
Appellants argue that it would not be possible for melted metal to be absorbed by Fujita’s
polysilicon pad 12 due to the intervening silicon nodule (15) (brief, page 6). Because, as in appellants’
method, Fujita’s constricted metal is melted and thereby severed by passing current through the metal
(Fujita, page 6; appellants’ specification, page 6), and because Fujita’s metal layer is in contact with the
silicon nodule and polysilicon layer 12, there is reason to believe that, as in appellants’ method, the
melted metal is absorbed by polysilicon in the nodule and/or polysilicon layer 12. In other words,
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Last modified: November 3, 2007