An Improved Model on Buried-Oxide Damage for Total-Ionizing-Dose Effect on HV SOI LDMOS

The distribution of radiation induced positive oxide trapped charges (Not) in buried oxide (BOX) with different applied electric fields for high-voltage (HV) SOI LDMOS is investigated. In contrast to the traditional model which depends upon Not buildup near the interface that the field line points to, the verified experimental results in this work indicated that there are still a non-negligible set of Not generated in SOI/BOX interface even if the electric field plays a negative role (field line perpendicular to the SOI/BOX interface pointing from the top to the bottom of the BOX). The improved model on BOX damage induced by TID considering this set of Not and its saturation effect is proposed and adopted in accurate simulated analysis to predict the post-irradiation device behavior. The mechanism of HV SOI LDMOS degradation during irradiation is also revealed. The radiation hardening LDMOS in this work keeps breakdown voltage above 120 V at D=500 krad(Si).