Microstructural and compositional failure analysis of Cr-CrCu-Cu thin films for ball grid array (BGA) applications

Abstract

A PVD Cr-CrCu-Cu metal scheme for flip chip applications was investigated varying the conditions of deposition power and temperature, and film thickness. The thin film stress and resistivity of the Cr-CrCu-Cu multilayers and the effect of film and thermal cycle reliability were studied. Thermal cycle reliability results proved to be a function of both the CrCu alloy and the Cu overlayer thickness. Analytical Electron Microscopy (AEM) results support the diffusion barrier relationship of CrCu layer.