Prediction of Electromigration Failure in Passivated Polycrystalline Line Considering Passivation Thickness

It is known that the lifetime of the passivated metal line varies depending on kind and thickness of the passivation layer. The appropriate consideration of the effect of passivation on electromigration damage makes it possible to evaluate the reliability of the metal line with choosing kind or thickness of the passivation. This paper is focused on the effect of passivation thickness on the failure prediction. The failure prediction considering the passivation thickness is shown. First, the film characteristic constants depending on the passivation thickness are experimentally determined in the lines with three kinds of passivation thickness. Next, by extrapolating the obtained dependencies, the characteristic constants are determined to predict the lifetime of the line covered with the thicker passivation than that employed in the experiment, and the lifetime is predicted by the reliability evaluation method based on the numerical simulation.