Total dose effects on a fully-depleted SOI NMOSFET and its lateral parasitic transistor

The total dose-induced threshold voltage shift of fully-depleted NMOS transistors is strongly correlated with charge trapping in the buried oxide. Thinner buried oxide, though less dose sensitive than thicker, does not necessarily improve the radiation hardness of fully-depleted transistors because of the higher coupling effect. The lateral parasitic transistor characteristics are more sensitive to buried oxide trapping than those of the main active transistor. The back surface conduction in the thin part of the mesa edge increases with ionizing dose and adds to the front surface conduction