A two-stage model for negative bias temperature instability

Based on the established properties of the most commonly observed defect in amorphous oxides, the E' center, we suggest a coupled two-stage model to explain the negative bias temperature instability. We show that a full model that includes the creation of E' centers from their neutral oxygen vacancy precursors and their ability to be repeatedly charged and discharged prior to total annealing is required to describe the first stage of degradation. In the second stage a positively charged E' center can trigger the depassivation of P_b centers at the Si/SiO₂ interface or K_N centers in oxynitrides to create an unpassivated silicon dangling bond. We evaluate the new model to experimental data obtained from three vastly different technologies (thick SiO₂, SiON, and HK) and obtain very promising results.