An alternativemodel for interconnect low-k dielectric lifetime dependence on voltage

Abstract

Low-k dielectrics used in interconnect systems of advanced microelectronics devices tend to degrade faster than gate oxide under electric field. As spacing between metal lines shrink, degradation models like the E-model, which are used to extrapolate time-dependent dielectric breakdown under constant voltage stress conditions back to operating voltages, give too conservative lifetimes. This paper suggests a simple model to explain the nature of the field-and current-induced degradation. It is based on observations of trapped charge and leakage behavior as a function of time under a constant voltage stress. This model predicts that as the stress voltage is lowered to a typical operating regime, the lifetime increases dramatically, and that using a more lenient radic(E )-model for lifetime prediction is still safe.