Total Ionizing Dose Hardening of 45 nm FD-SOI MOSFETs Using Body-Tie Biasing

Abstract

The total ionizing dose (TID) effect is a problematic concern in fully depleted silicon-on-insulator (FD-SOI) metal-oxide-semiconductor transistors (MOSFETs) because of the introduction of the thin buried oxide layer. The device performance is degraded by the radiation-induced trapped charges in the oxide, which cause threshold-voltage drifts and OFF-state leakage-current increments. This paper proposes a novel strategy for TID hardening in FD-SOI devices by using body-tie biasing. First, an n-type three-dimensional FD-SOI MOSFET with a gate length of 45 nm is built, and the irradiation-induced charge trapping in the oxide structures is simulated under different bias conditions. The responses of the floating-body FD-SOI devices and the devices with an additional body-tie, to the total dose and interface charges, are simulated and compared. The results show that the tied-body structure is more tolerant to the TID effect than the floating-body structure and that it can endure up to 100 krad of TID irradiation without body-tie biasing. To mitigate the degradation of the tied-body device at high dose levels, body-tie biasing is used, and the “repairing” voltage” at different dose levels is calculated. By applying the “repairing voltage” to the body-tie, the irradiated device can be restored to the pre-irradiation state efficiently.

Keywords

• Fully depleted silicon-on-insulator (FD-SOI)
• total ionizing dose (TID)
• floating-body
• tied-body
• body-tie biasing