Microstructure evolution and failure mechanism of electromigration in Ag-alloy bonding wire

Ag-alloy bonding wire has excellent physical properties and is widely applied in microelectronics, but growing concerns about circuit failure induced by electromigration (EM) have raised doubts about this material. One point of frequent debate is the diffusion mechanism. This study provides a novel perspective by investigating the evolution of the microstructure via electron backscatter diffraction (EBSD) to settle the controversy over the diffusion mechanism of Ag-alloy bonding wire during EM. Particular focuses are the propensity for grain growth, the effects of the coincidence site lattice (CSL) on the grain boundary network, the texture transition, and the influence of thermal energy during EM. A stage-like transition in the dominant diffusion mechanism in different stages of EM is proposed and substantiated from the viewpoint of microstructure evolution.