Numerical simulation of current crowding phenomena and their effects on electromigration in very large scale integration interconnects

Two types of current crowding structures were simulated in this work. In each structure, both the pattern of current crowding and the magnitude of the associated current density gradient were examined. Factors like line width, curvature, and conductivity, which affect the crowding behavior, were analyzed. The numerical magnitude of the gradient, which changes to a driving force when a potential in the gradient is defined, was found to be high enough to affect the atomic rearrangement during electromigration. It induces void formation in the low current density region of an interconnect, and it causes precipitates to link together rather than to ripen in a two-phase alloy. Also, we found that as the line width scales down, the effects of current crowding become more and more significant.