Microstructural effects upon stress-migration resistance were investigated in 2 types of electroplated Cu metallization having a <111> texture or a random texture. Transmission electron microscopy revealed incoherent twins in the <111> textured films, but 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. It was pointed out that, unlike conventional Al interconnects, a strong <111> texture should be avoided in order to minimize stress-migration failure in Cu interconnects.

Microstructural Influences on Stress Migration in Electroplated Cu Metallization. A.Sekiguchi, J.Koike, K.Maruyama: Applied Physics Letters, 2003, 83[10], 1962-4