Appeal No. 2000-0239 Page 2
Application No. 08/839,843
leaves a void in the interconnection. Growth of the void
increases the electrical resistance of the interconnection to a
point where the associated IC fails.
The appellants assert that their invention eliminates void
growth by “the short-length effect.” (Spec. at 2-3.) More
specifically, the short-length effect occurs in short aluminum
interconnections if an electrical current is supplied through
leads of materials in which aluminum diffusivity is low. The
physical origin of the short-length effect is the build-up of
backstress as aluminum atoms pile up against the diffusion
barrier leads; this backstress counteracts the electromigration
driving force. A steady-state condition arises in situations
where the backstress balances the electromigration driving force.
Under this condition, “no further electromigration damage
results.” (Id. at 3.)
The appellants’ invention features segments of aluminum
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