Impact of wire material and fluorine in dielectric on wire Pull Test stress

Abstract

The move towards low-k dielectrics and change of wire material from gold (Au) to copper (Cu) is being driven by the need for lower resistive-capacitive (RC) delay in circuits and cost. But this can increase the incidence of bond pad lifting. Finite element analysis (FEA) stress simulation prior to mass production can provide an insight to the probability of such failures and guide device manufacturers to focus their efforts on factors that are significant. In this work, it was discovered that the change in wire material has a higher impact to back end of line (BEOL) structure's first principal stress compared to the change in the low-k dielectric material properties.