Numerical simulations of stress induced void evolution and growth in interconnects

Abstract

We model stress driven void growth and evolution in representative interconnect microstructures. Our computations account for several kinetic processes involved in interconnect failures, including surface diffusion, interface and grain boundary diffusion, as well as sliding on grain boundaries or the interconnect/passivation interface. Depending on the relative rates of these processes, we predict several different regimes of behavior for the void. In some cases the void remains rounded, leading to a long interconnect life. For critical combinations of material properties, however, the void propagates across the line as a narrow slit, causing rapid failure. Our analysis suggests that the extent of inelastic slip between the interconnect and the surrounding passivation plays a central role in this transition. Implications for interconnect reliability are discussed.