The morphological evolution of hillocks at the unpassivated side-walls of single-crystal metallic thin film interconnects was investigated via computer simulations using the free-moving boundary value problem. The effect of drift-diffusion anisotropy on the development of surface topographical scenarios was fully explored under the action of electromigration and capillary forces, utilizing numerous combinations of the surface texture, the drift-diffusion anisotropy and the direction of the applied electric field. The simulation studies yield analytical relationships for the velocity of the surface solitary waves and the drift velocity of electromigration-induced internal voids as a function of the applied current densities, which contained intrinsic and structural properties of the single-crystal thin films. The threshold value of the applied current density, above which electromigration-induced internal voids could be formed and could cause the catastrophic failure of interconnects by breaching, also appeared explicitly in this relationship.

Morphological Evolution of Edge-Hillocks on Single-Crystal Films Having Anisotropic Drift-Diffusion under the Capillary and Electromigration Forces. T.O.Ogurtani, A.Celik, E.E.Oren: Thin Solid Films, 2007, 515[5], 2974-83