TID-Induced OFF-State Leakage Current in Partially Radiation-Hardened SOI LDMOS

Abstract

The electrical characteristics of silicon-on-insulator (SOI) n-channel laterally diffused metal oxide semiconductor field effect transistors (NLDMOSFETs) are examined after exposure to the total ionizing dose (TID). The devices are partially radiation hardened in that the gate oxide (GOX) and the field oxide (FOX) have undergone a hardening process, but not the buried oxide (BOX). Two bias conditions, OFF-state and all terminals grounded, during irradiation are examined. The irradiated device shows that the OFF-state leakage current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ) of these devices increases with the accumulated dose. The physical mechanisms for the I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> are analyzed by technology computeraided design (TCAD) simulation. The OFF-state leakage current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</sub> ) can be explained due to the effects of radiation-induced trapped charge at the BOX silicon interface.