Variability challenges to electromigration (EM) lifetime projections

Technology scaling has led to severe degradation of EM performance for advanced interconnects. On one hand, the median time to failure becomes shorter due to the reduction of critical void size and the increase of the Cu mass flow rate. On the other hand the variability increase has led to broader failure time distributions, which can be more detrimental for lifetime projections to very low percentiles at use conditions. In this paper, we present case studies to show that the failure time improvements can be overshadowed by the distribution shape factor degradation. Causes and implementations are also discussed.