An advanced finite element strategy for thermal stress field investigation in aluminum interconnections during processing of very large scale integration multilevel structures

An advanced strategy for modelling the thermal stress induced in aluminum interconnections during processing of multilevel structures is presented. The advantage of the approach described is that it allows the residual stresses from one processing step to be used as the initial conditions for a subsequent step. 2D elasto-plastic model (von Mises plastic criterion) is implemented in Finite Element Code and it is shown that even after significant relaxation by plastic deformation, high thermal stress resides in the aluminum line in both width and thickness directions. The technique demonstrated here is for a silicon-glass-aluminum-glass structure. However, it is readily extended to more complex situations and material combinations.