Simplified model for radiation effects in MOS devices

Abstract

The spatial distribution of trapped holes in the gate oxide of MOS exposed to ionizing radiation plays a significant role in the dynamics of the threshold voltage shift with dose, specially when switched bias measurements are considered. In this work, we analyze currently available simplified models stressing out their limitations when dealing with complex measurements. Therefore, we present a simplified model based on the fitting of the evolution with dose of the spatial distribution of trapped holes obtained from a physics-based numerical model. For that, a two-exponential expression was considered, with four fitting parameters. Then, the change with dose of these parameters is considered. The effect the variation of the capture and neutralization rates has on the spatial distribution of trapped holes is analyzed to better understanding radiation effects in MOS devices and also to contribute to the development of simplified numerical models capable of reproducing complex dynamics.