It was noted that small amounts of alloying elements could significantly retard electromigration in conductor lines. This was well-established experimentally, but lacked a fundamental explanation. An atomic-scale mechanism for this behavior was proposed here which was based upon a kinetic analysis of diffusion in crystalline interfaces. It predicted the occurrence of a reduction in, or reversal of, the flux of host atoms for physically reasonable parameters and could account for the observed effect of Cu upon electromigration in Al conductor lines.

Alloying Effects on Electromigration Mass Transport. J.P.Dekker, C.A.Volkert, E.Arzt, P.Gumbsch: Physical Review Letters, 2001, 87[3], 035901 (4pp)