It was recalled that it was necessary to take account of the stress dependence of atomic mobility when describing stress, in a metallic conductor, which was caused by electromigration. The role of this dependence was considered here in more detail, and led to qualitatively new results concerning stress evolution and drift kinetics. The stationary stress distribution over the length of the elastic zone of the conductor was shown to be non-linear and asymmetrical under super-threshold conditions, with the zone of compressive stress being more extensive than that of tensile stress. This resulted in an asymmetrical pattern of plastic deformation, with the hillock-zone being more extensive than the voided region at the cathode. The drift-rate was shown to attain its maximum value during the non-stationary stage of stress evolution, and it then fell back to its stationary value. The duration of the non-stationary stage of stress evolution was proportional to the conductor length and was inversely proportional to the current density. This was different to the results obtained by all previous studies. The present model also predicted that, for conductors having a length that was much greater than the critical one, the non-stationary stage of stress evolution corresponded to a quasi-stationary stage in the drift kinetics, during which a constant drift-rate was observed.

Modelling Electromigration-Induced Stress Evolution and Drift Kinetics with a Stress-Dependent Diffusivity. S.A.Chizhik, A.A.Matvienko, A.A.Sidelnikov, J.Proost: Journal of Applied Physics, 2000, 88[6], 3301-9