A comprehensive physically based predictive model for radiation damage in MOS systems

We have developed a comprehensive physically based predictive model for radiation damage in MOS devices. The model involves essentially no adjustable parameter first principles calculations of both oxide hole trapping and interface trap generation. With both oxide positive charges and interface trap generation accounted for, in principle, the model allows calculation of the threshold voltage shifts from processing parameters. The model is based on the statistical mechanics of point defects in solids and extensive electron spin resonance (ESR) measurements of MOS systems. Although we believe that this model is fundamentally correct and that it captures most of the fundamental physics of the damage phenomena, we emphasize that the treatment is first order. The model involves some simplifying assumptions and in its present form, it applies only to high quality thermally grown oxides. We present the model as a framework for understanding the radiation damage process and as a means to explain a very wide variety of apparently unrelated observations long present in the literature. We believe the approach outlined in this paper will eventually allow manufacturers to build in radiation hard reliability with process design.