MOSFET prediction in space environments

Abstract

This paper gives the approach to the prediction of MOSFET response in space environments based on mathematical modeling. The appropriate model, called the Conversion model, is developed for the description of the numbers of oxide trapped charges and interface states as functions of irradiation dose and annealing time. The central point of this model is the numerical relationship between oxide charge annealing and interface states build-up. The dependence of the annealing process on time can be described by linear response theory, as well as on the basis of a more generalized approach, taking into account tunneling and thermal effects. Parameters of the model are extracted from characteristics, obtained in laboratory tests, when transistors are irradiated at relatively high dose rates with X-rays and then annealed. The results can be extrapolated to the range of dose rates, typical for space applications. For implementation of conversion model predictions in circuit simulation they are converted into the shifts of MOSFET parameters for SPICE.