Finite element investigations of mechanical stress in metallization structures

For different double layer metallization structures the thermal-electrical-mechanical stress due to the mismatch of thermal expansion coefficients and elastic moduli was calculated by finite element analysis. A quantitative comparison between a conventional structure with small aluminum step coverage as well as an aluminum plug, a tungsten filled via structure and a structure with a barrier layer was done. The influence of applied current density, metallization length and passivation thickness and material was investigated for the tungsten filled via structure.