Microstructural and surface effects on electromigration failure mechanism in Cu interconnects

It is shown that changes in the microstructure of Cu interconnects lead to qualitative variation in electromigration damage kinetics - from the formation of the open circuit to continuous damage not leading to failure. Surface diffusion acting simultaneously with grain boundary mass transport is shown to be critical for damage formation. Activation energy of electromigration was measured to be 0.95 eV.