A model for electromigration-induced degradation mechanisms in dual-inlaid copper interconnects

Incorporation of all important atom migration driving forces into the mass balance equation and its solution together with solution of the coupled electromagnetics, heat transfer, and elasticity problems allows one to simulate electromigration (EM)-induced degradation in a variety of dual-inlaid Cu interconnect segments characterized by different dominant channels for mass transport. The interface bonding strengths, significantly influencing the interface diffusivity and consequently the mass transport along interfaces, result in completely different degradation and failure pictures for the weak and strengthened Cu/capping layer interfaces. Strengthening of the top interface of the inlaid Cu interconnect metal line is a promising way to prolong the EM lifetime. The results of the numerical simulation have been proven by EM degradation studies on test structures in an in-situ scanning SEM experiment. The correspondence between simulation results and experimental data indicates the applicability of the developed model for the optimization of the physical and electrical design rules.