Dose dependence of interface traps in gate oxides at high levels of total dose

Interface traps in gate oxides were found to saturate at high total dose levels. An empirical model was developed to describe the nonlinear dependence and saturation characteristics. Three different processes were studied, namely, CMOS/SOS, hardened bulk CMOS, and unhardened bulk CMOS, using several combination of dose rate and bias. An evaluation was made of the model's accuracy in extrapolating the effect of interface traps to very high doses. A possible application of the model in characterizing devices for space environments is discussed along with implications for a physical model of radiation-induced interface trap building.>