γ-irradiation hardness of short-channel nMOSFETs fabricated in a SOI technology

Abstract The increased use of custom-of-the-shelf (COTS) components for space applications necessitates a better insight into the radiation hardness of scaled down technologies. The present study investigates the impact of γ-irradiation up to 100 krad (Si) on the electrical performance of SOI MOSFETs with 0.5–2.0 μm channel lengths. Attention is given to the threshold voltage, the maximum transconductance and the electron mobility in the channel. The influence of a subsequent 15 min thermal anneal at 315 and/or 415 °C is also pointed out. Both the oxide thickness and the concentration of the boron doping in the channel have an impact on the radiation hardness. Depending on the irradiation conditions and the transistor doping profiles, either a net negative or positive radiation-induced charge is built up in the oxide and at the interface. A model, based on the incorporation of B atoms in to the oxide layer, is proposed to explain the experimental observations. The anneal efficiency depends on the technological parameters, the irradiation dose and the anneal conditions. In some cases a low dose irradiation and subsequent anneal have a beneficial impact on the electrical device performance.