New insights in polarity-dependent oxide breakdown for ultrathin gate oxide

In this work, a quantitative analysis is applied to resolve the newly reported polarity-dependent charge-to-breakdown (QBD) data from thick oxides of 6.8 nm down to ultrathin oxides of 1.9 nm. Three independent sets of QBD data, i.e., n+poly/NFET stressed under inversion and accumulation, and p+poly/PFET under accumulation are carefully investigated. The QBD degradation observed for p-type anodes, either poly-Si or Si-substrate, can be nicely understood with the framework of maximum energy released by injected electrons. Thus, this work provides a universal and quantitative account for a variety of experimental observations in the time-to-breakdown (TBD) and QBD polarity-dependence of oxide breakdown.