Analytical and simulation-based risk assessment of imprint depth and brittle fracture in bond pad stacks

Abstract

During electrical wafer testing and wire bonding onto pad metallization, oxide layers in Backend-of-Line (BEOL) pad stacks are exposed to the risk of mechanical damage. Subsequent metal migration into oxide cracks leads to electrical device failure. We undertook simulation-based risk assessment using analytical and Finite Element Modelling (FEM) with regard to critical imprint depths in top metallization layers of elementary metal-oxide test vehicles. Our modelling outcomes cope well with results obtained by instrumented indentation and, thus, constitute a promising physics-of-failure approach towards minimizing the risk of lifetime-limiting oxide fracture.