  In this paper, we modeled and simulated uneven current distribution for
on-die interconnect structure. We show significant difference when considering
uneven current distribution. Finite Element Method approach is used to analyze
various variation effects. Blech length effect and analytical EM lifetime
calculation is used to quickly identify on-die EM weak wires. We propose a
random walk based approach to evaluate on-die variation impact on
electromigration reliability. Experimental results show substantial EM
degradation with variation effects present.
