Calculation of the probability of hole injection from polysilicon gate into silicon dioxide in MOS structures under high-field stress

Abstract

A theoretical study of the mechanism for hole injection from the degenerately doped poly-Si gate into the gate oxide in metal–oxide–silicon (MOS) structures under high-field stress (5–15 MV/cm) is presented. Our theoretical model for the anode hole injection mechanism (AHI) is due to the injection of holes generated by impact ionization of energetic electrons entering into the conduction band of poly-Si gate from the oxide conduction band under the applied electric field. An analytical approach is proposed on the basis of the above injection mechanism to estimate the hole injection probability per injected electron in order to utilize these data in MOS device simulation under high-field Fowler–Nordheim (FN) stress. The computed values of anode hole injection probability data are compared with experimental results. Using the anode hole injection probability from the present model, we have predicted thin tunnel gate oxide degradation under constant current and voltage FN stress.