Cu-Al IMC degradation under high electric fields during HTOL tests

Copper wirebonding is becoming mainstream even under more extreme conditions. Therefore, it is of crucial importance, to understand failure mechanisms of the Cu-Al system under high temperature conditions. A lot of work has been done to assess the high temperature stability of Cu-Al contacts (e.g. High Temperature Storage Life/HTSL) or its stability under biased humidity conditions (e.g. the Highly Accelerated Stress test/HAST). A few papers have described the impact of current and its direction on Cu-Al degradation. However, very limited work has been published involving the simultaneous impact of high temperature and high bias, without humidity. In this paper, we describe the failure mechanism of the Cu-Al contact under the influence of elevated temperature and high electric fields. The impact of the Epoxy Molding Compound/EMC, testing condition and relation to application mission profile is described with a semi-empirical model.