Impact of line width on hydrostatic stress and stress-induced voiding in Cu interconnects

Hydrostatic stress of Cu damascene interconnects was calculated by using finite element method in the present work. The analytical work was performed to examine the distribution of hydrostatic stress and the effect of different line width in the Cu interconnects. Then a model of atomic diffusion was presented and used to calculate the size of stress-induced voiding according to result of hydrostatic stress. The results indicate that the stress is highly non-uniform throughout the Cu structure and the highest tensile hydrostatic stress exists on the bottom interface, and the size of stress-induced voiding is strongly dependent upon line width in Cu interconnects.