Analysis of stress induced voiding using by finite element analysis coupled with finite difference analysis

In this paper, the vacancy migration in Cu interconnect of large scale integration caused by stress induced voiding was calculated using the α multiplication method. Then, the effect of weight coefficient, α, on stress induced vacancy diffusion analysis was investigated and the validity of the α multiplication method was verified. Furthermore, the method of the vacancy diffusion analysis coupled with thermal stress analysis which can consider the history of thermal stress due to temperature changes was proposed. The results of the vacancy diffusion analysis coupled with the thermal stress analysis were compared with the analytical results of the vacancy migration without the effect of history of thermal stress. As a result, the maximum site of vacancy accumulation was found to be qualitatively in good agreement between them. However, the quantitative value of maximum vacancy concentration obtained by the vacancy diffusion analysis coupled with thermal stress analysis was found to be much higher and the vacancy distribution is found to be much more localized.