Microstructural influences on stress migration in electroplated Cu metallization

Abstract

Stress migration in advanced Cu interconnects leads to device failure and to poor production throughput. In this work, microstructural effects on stress-migration resistance were investigated in two types of electroplated Cu metallization having a 〈111〉 texture and a random texture. Transmission electron microscopy showed incoherent twins in the 〈111〉 textured films whereas coherent twins in the random textured films. The incoherent twins were found to accompany stress-induced voids because of a weak bonding at twin interfaces. Unlike conventional Al interconnects, a strong 〈111〉 texture should be avoided to minimize stress-migration failure in Cu interconnects.