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.
Highlights
The fully depleted silicon-on-insulator (FD-SOI) metaloxide-semiconductor transistors (MOSFETs) has been proven to be more tolerant to single-event effects than its bulk silicon MOSFETs due to its ultrathin body region and buried oxide layer [1], [2]
In this work, an n-type three-dimensional FD-SOI MOSFET with 45 nm gate length was built, and the irradiation-induced charge trapping in the buried oxide (BOX) layer and shallow trench isolation (STI) layer under OFF bias and TG bias were simulated
The charge trapping profiles under the TG bias condition at different dose levels were used to simulate the total dose response of the floating-/tiedbody FD-SOI device, and the results showed that the FDSOI MOSFET with body-tie was more tolerant to total dose irradiation than the floating-body structure
Summary
The fully depleted silicon-on-insulator (FD-SOI) metaloxide-semiconductor transistors (MOSFETs) has been proven to be more tolerant to single-event effects than its bulk silicon MOSFETs due to its ultrathin body region and buried oxide layer [1], [2]. The total ionizing dose (TID) effect becomes more complex in FD-SOI devices, because of irradiation induced positive trapped charges consists of holes captured by oxide traps in the thin buried oxide (BOX) layer and the shallow trench isolation (STI), as well as on the silicon/oxide interface, which interfere severely with the normal operation of the device. Efforts have been made to mitigate the degradation induced by total dose irradiation in FD-SOI MOSFETs, including body doping, radiation hardening design [8], substrate biasing [9] and introduction of body-tie [10]. Introduction of body-tie into the body region of FD-SOI devices seems to be a more efficient method, this irradiation hardening strategy has not been studied in detail
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