Probing into the asymmetric nature of electromigration performance of submicron interconnect via structure

The void locations of via electromigration failures for multi-level dual damascene copper interconnect structure are highly asymmetric with respect to the current flow direction. In this work, finite element analysis is performed to investigate the nature of the asymmetries, and to identify the likely failure locations in the via structures at different test conditions. By coupling the current density, temperature and the stress fields in the analysis, and using the site with maximum atomic flux divergence as the void location site, a good correlation between the model predictions and experimental observations is obtained.