Degradation of oxides and oxynitrides under hot hole stress

The impact of nitridation on hot hole injection and the induced degradation is quantitatively studied by comparing the behavior of a control oxide and oxynitrides. The oxynitride is prepared by either annealing the oxide in N₂O or growing directly in N₂ O. The pMOSFET´s are uniformly stressed by using the substrate hot hole injection technique. The physical quantities analyzed include the hole injection current, the density of created interface states and the density of trapped holes. It is found that a 30 min annealing in N₂ O at 950°C can enhance the effective barrier for hole injection by 0.6 eV. However, the interface state generation during the injection is insensitive to nitridation. The continuing degradation post the hole injection is also investigated. This includes a poststress interface state build-up and the generation of new precursors for interface states. The nitridation reduces the poststress degradation considerably. Where it is necessary, the hole induced degradation is compared with that induced by electrons. The applicability of the models proposed for oxynitrides to the present results is examined