Spatial Dependence of Trapped Holes Determined from Tunneling Analysis and Measured Annealing

Accurate predictions of the post-irradiation response of microelectronic circuits is an important and difficult problem. We present a tunneling model for MOS structures showing how the post-irradiation annealing deviates from a simple ln(t) dependence for a nonuniform spatial trap distribution. This model is applied to our measurements of post-irradiation response to extract spatial trap distributions for several oxides. Results of this analysis have important implications for testing and hardness assurance--accurate prediction of the long-term response of hardened circuits requires a measure of the deviation from logarithmic annealing.