  Ionizing radiation induces defects in STI oxides in current MOSFETs. These
defects may degrade the performance of the MOS circuit. Analytical models for
the buildup of these defects during the radiation exposure are available in
literature. In this paper, we show that the classical model used to estimate
the buildup of TID-induced traps in MOSTs predicts inaccurate results at high
radiation levels. We, further, introduce an improved model to estimate the
buildup of defects that is valid for both low and high radiation doses. Our
improved model is compared to published data showing its validity.
