Dielectric breakdown mechanism in thick SiO/sub 2/ films revisited

The dielectric breakdown in thick (T/sub ox/>15 nm) SiO/sub 2/ films is examined, focusing on its statistical properties. Time-dependent dielectric breakdown is measured using the Fowler-Nordheim and the substrate hot hole injection techniques, under various bias conditions. It is demonstrated that in thick oxide films, the Weibull slope is a function of the stress condition, and it is much smaller than the value predicted by the percolation theory. We discuss the effect of trapped holes on the breakdown statistics.