Small amounts of alloying elements can significantly retard electromigration in conductor lines. This phenomenon is experimentally well established but is still lacking a fundamental explanation. An atomic-level mechanism for this behavior is proposed here which is based on a kinetic analysis of diffusion in crystalline interfaces. It predicts a reduction or reversal of the flux of host atoms for physically reasonable parameters and can account for the observed effect of copper on electromigration in aluminum conductor lines.

• Received 10 November 2000

DOI:https://doi.org/10.1103/PhysRevLett.87.035901