Film samples which were current-stressed under  in situ  ultra-high vacuum clean-surface conditions exhibited an activation energy for electromigration that lay within the range of values which were expected for surface diffusion. Field ion microscopic studies of {001} face-centered cubic metal surfaces showed that the application of an electric field to the surface could affect the rate of surface diffusion. Positive and negative potentials were here applied to Cu stripes which were undergoing electromigration damage under ultra-high vacuum clean-surface conditions. The activation energies were measured, as a function of applied potential, by using a resistance-change method. The results revealed a strong dependence of the activation energy for electromigration upon the sign and magnitude of the applied potential. It was found that positive potentials increased the activation energy, while negative potentials decreased it. These results were expected to have practical uses in controlling the rate of electromigration damage, in passivated metal interconnects, where the damage mechanisms could involve volume, grain boundary, interfacial and surface diffusion processes.

B.H.Jo, R.W.Vook: Applied Surface Science, 1995, 89[3], 237-49