Electrothermomigration-induced failure in power IC metallization

Metal migration by driving force of electron-flow and temperature gradient is a major reliability concern in power integrated circuits, especially for advanced integrated circuits where there are increasing density of the integrated power components and power dissipation. In this paper, we present a study of the combined effects of electromigration and thermomigration. A special test chip is designed for this study, in which several on-chip heater elements and temperature sensor are realized to impose and measure a temperature gradient, respectively. Our experimental results show that the electromigration lifetimes are much shorter in the presence of a temperature gradient than in a uniform temperature. The shortening of the electromigration lifetimes can be attributed to the effect of temperature gradient on electromigration-induced failure, rather than an additional driving force by thermomigration (due to a temperature gradient). Our observation is in qualitative agreement with recent theoretical model.