Uniformity impact on the upstream Electromigration of 40nm low-k Cu interconnect

Uniformity impact of metal and via on upstream Electromigration (EM) was investigated in Cu interconnect based on 40nm technology node. It is found that EM time-to-failure (TTF) log-normal main distribution can be improved by better metal uniformity. It is also observed that EM performance can be greatly enhanced by improving via and metal uniformity with NFC pull back recipe.