ABSTRACT
This chapter discusses failure mechanisms that are a superset of all the mechanisms that will occur in various package elements in both bipolar and field-effect devices. For some mechanisms, more than one model has been proposed to characterize the temperature dependence of the failure process. Most of the commonly accepted models have been discussed in such cases, along with their implicit assumptions. Thus, the steady-state temperature dependence of electromigration is of the same magnitude as that of grain-boundary diffusion. Silicon initially exhibits a positive temperature coefficient of resistivity, but reaches a peak value in the neighborhood of 160°C, and thereafter exhibits a large negative temperature coefficient of resistivity. While ionic contamination and surface charge spreading are failure processes for MOSFETs, second breakdown is a failure mechanism typically found in bipolar devices. Temperature-related models have been used to derive derating criteria for determining the maximum and minimum allowable temperature stresses for a given microelectronic package architecture.
