Prediction of electromigration failure in passivated polycrystalline line

Abstract

Mechanical stress or atomic density distribution in passivated metal lines is induced by electromigration, and plays an important role in the mechanism of electromigration damage. Recently, a governing parameter for electromigration damage in passivated polycrystalline lines, atomic flux divergence (AFDgen*), was formulated by adding the effect of the atomic density gradient to the governing parameter for electromigration damage in unpassivated polycrystalline lines, AFDgen. The latter has already been utilized to construct a prediction method for electromigration failure in unpassivated lines, as the first step toward the development of a practical method. In this article, a prediction method for electromigration failure in a passivated polycrystalline line is proposed using AFDgen*. It is shown that the proposed method is able to predict the failure location as well as the lifetime of the passivated polycrystalline lines. Both the lifetime and the failure location in a passivated polycrystalline line are predicted by means of numerical simulation of the failure process covering the building up of atomic density distribution, void initiation, void growth, and ultimately—line failure. The usefulness of this method is verified by an experiment where two passivated straight lines with different lengths are treated.