Theoretical Understanding of Electromigration-Related Surface Diffusion and Current-Induced Force in Ag-Pd Systems

Electromigration, as a common reason for interconnect failure, is becoming increasingly important in the ongoing decrease in the integrated circuit manufacturing process. A study is being carried out utilizing the ab initio calculational method to gain a deeper understanding of electromigration, with a focus on the atom diffusion process in the Ag-Pd alloy system, a commonly used interconnect material. We begin by establishing that the primary mechanism of diffusion is step-edge diffusion on the (111) surface. Following this, we examine the current-induced force exerted on the migrating Ag atom. The Pd substitutional defect reveals an effect that increases the energy barrier of diffusion and decreases the current-induced force that powers the directional migration.