Correlation between resistance behavior and mass transport in Al–Si/Ti multilayer interconnects

In this work we investigate the correlation between the resistance behavior and the mass transport in narrow line interconnects with a laminated structure incorporating single or multiple layers of Ti in AI-Si. For comparison, homogeneous AI-Si films are also studied. A temperature-ramp resistance analysis is applied at direct wafer level. In multilayer interconnects the resistance change is only detected above the typical failure temperatures of the homogeneous stripes. Different degradation mechanisms are also observed, although the activation energies suggest similar electromigration processes. The improved stability against electromigration in the laminated structures is related to the formation of a continuous barrier of the intermetallic compound TiA1₃ preventing voids from propagating across the film.