Effect of Redundant Microstructure on Electromigration-Induced Failure

Abstract

Aluminum films with grain boundaries staggered throughout the film thickness, and hence with nonoverlapping sites for electromigration‐induced failure, were prepared by vacuum deposition in layered or extremely fine‐grained form. Mean lifetimes before the occurrence of electrical opens were an order of magnitude larger than those for control films having non‐redundant grain structure. Heat‐treatment effects which reduced lifetimes to values comparable to control lifetimes were interpreted in terms of either a lifetime minimum for grain size ∼ 0.6 μ or disruption of the layered structure.