GRAIN BOUNDARY MIGRATION IN METALLIC INTERCONNECTS

摘要

The parallel levelset environment for nanoscale topography evolution (PLENTE) [Bloomfield ct at.}, and a simple grain boundary migration model are used to investigate the evolution of grains in polycrystalline metallic interconnects. The driving force in this grain boundary migration model is the elimination of surface energy associated with grain boundaries, in a process activated by temperature. The mass fluxes of material parallel to grain boundaries and along the metal-barrier interface are considered to be small compared to motion transverse to the grain boundaries. The initial films, formed by electroless deposition simulations, exhibit approximately log-normal distributions of grain sizes. During the annealing simulations, the structures begin to coarsen, with larger grains swallowing smaller grains, and the log-normal grain-size distributions become bimodal. Computed trends are similar to those experimentally observed in high temperature annealing and low temperature "self-annealing" of copper [Zielinski et al.]. The timescales of the simulated annealing processes compare qualitatively with experimental timescales, using representative physical and energetic parameters from the literature.