Substrate effect on radiation-induced charge trapping in buried oxide for partially-depleted SOI NMOSFET

Abstract

The total-ionizing-dose response of partially-depleted silicon-on-insulator devices with or without grounded substrate under different irradiation bias is investigated. Compared with devices with grounded substrate, the devices with floating substrate introduces more trapped positive charges in buried oxide after irradiation, leading to larger negative shift of back-gate threshold voltage, especially for ON bias condition. Theoretical analysis and TCAD simulation demonstrate that, this phenomenon is attributed to the increased initial built-in field in buried oxide and weakened space charge effect under the case of floating substrate. According to this work, substrate terminal of SOI devices must be considered for integrated circuit design under radiation condition.