Numerical simulation of DB-NBTI degradation caused by a sheet of interface charge

In this paper, we combine the Reaction-Diffusion Model of Negative Bias Temperature Instability (NBTI) with the two-dimension semiconductor device simulator, and calculate the interfacial charge after extracting the electric field across gate oxide and the hole density at Si/SiO2 interface. A novel non-uniform interface charge distribution model is proposed by taking a sheet of interface charge into account so that the device degradation of drain bias NBTI (DB-NBTI) can be simulated and analyzed. The results show that, as for DB-NBTI, under constant drain bias and part of NBTI interface charge still degrade with the exponent value of 1/6 of the Reaction-Diffusion Model, the degradation of threshold voltage deviates from the traditional power exponent of 1/6. The deviation of degradation curve can be explained by the comparison and analysis of the hole density at the Si/Si0₂ interface. These results are helpful in pushing DB-NBTI study, and improving the model and methods of its numerical simulation.