Local crystallography and stress voiding in Al–Si–Cu versus copper interconnects

Abstract

We compare the local crystallographic orientations associated with stress voids in Al–1Si–0.5Cu (wt %) with those in pure copper interconnects. Orientations were sorted by whether grains were immediately adjacent to voids. Grains adjacent to voids in Al–Si–Cu showed a 〈111〉 fiber texture that was slightly stronger than those in intact regions. This is in contrast to copper, which showed weaker local 〈111〉 texture around voids. We postulate the difference to be due to the relative effectiveness of the diffusion paths available in the lines. For Al–Si–Cu, the presence of defects associated with precipitates may allow more rapid diffusion than grain boundaries. Voiding in copper, which is free from such defects, depends more on grain boundary structure.