The grain-boundary Frenkel-pair model defect generation mechanism, and corresponding diffusion mechanisms during electromigration, were developed by using atomic simulation techniques. It was assumed that large numbers of interstitials and vacancies existed at grain boundaries, and that both defects contributed to mass transport. The Cu segregated preferentially to interstitial sites at grain boundaries, via a Frenkel-pair generation process, and reduced the overall grain-boundary diffusivity; due to the stronger Al-Cu binding. The predictions of the models were in excellent agreement with available experimental data.

Defect Generation and Diffusion Mechanisms in Al and Al-Cu. C.L.Liu, X.Y.Liu, L.J.Borucki: Applied Physics Letters, 1999, 74[1], 34-6