Assessing failure in microelectronic compounds

A strategy to estimate life expectation in copper vias is presented. To this end, two-scale finite-element simulations of thermal cycling are performed. The employed material model for the copper vias accounts for large elastic and plastic deformations and, additionally, for the growth of pores within the material.The common practice to extrapolate the accumulated plastic strain computed within a few steps of thermal cycling by means of a Coffin–Manson equation is critical examined. It is pointed out that a relatively large number of steps is necessary to obtain meaningful results. Furthermore, it is demonstrated that an extrapolation of the computed porosity up to a critical value allows for analogous conclusions.