The role played by dislocations in generating electromigration damage in model experiments was considered. Continuous segments of pure polycrystalline and monocrystalline conductor lines were plastically deformed by using nano-indentation methods, and were then subjected to in situ accelerated electromigration in a scanning electron microscope. It was found that electromigration damage was generated at plastically deformed segments in monocrystalline conductor lines, but not in polycrystalline lines. Investigations of the microstructure, using focussed ion beam and electron back-scattering diffraction techniques, did not reveal any signs of fine-grain recrystallization in the indented regions. This observation, and numerical estimates of the diffusivities which were involved, suggested that electromigration damage arose via rapid diffusion along dislocations at modest (1015/m2) densities.

Electromigration Damage in Mechanically Deformed Al Conductor Lines - Dislocations as Fast Diffusion Paths. S.P.Baker, Y.C.Joo, M.P.Knauss, E.Arzt: Acta Materialia, 2000, 48[9], 2199-208