The dependence of the subthreshold-swing (SS) degradation on fin width is reported for irradiated 100-nm-gatelength, fully depleted -channel FinFETs. The wider the fin is, the greater the radiation-induced SS degradation. The higher tolerance to radiation-induced charge for the narrower FinFETs is attributed to the additional lateral gate control over the body potential. The irradiation and room temperature annealing results suggest that the SS increase for wider FinFETs is due primarily to nonuniform trapped charge in the buried oxide (BOX). The subthreshold characteristics of FinFETs with two fins are more likely to exhibit a nonuniform subthreshold slope (NUSS), resulting from fin-to-fin variability, than FinFETs with 20 fins, where the corresponding -gs curve is the composite of the 20 individual -gs curves.Index Terms-Annealing, buried oxide (BOX), fin width, fully depleted (FD) FinFETs, silicon-on-insulator (SOI), subthreshold swing (SS), total ionizing dose (TID).

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We have performed an experimental study of the effects of ionizing radiation and bias-temperature stress on Si MOS devices with HfSiON gate dielectrics. We compare the responses of homogeneous high-Si 3 N 4 films and low-Si 3 N 4 films that contain crystalline HfO 2 . We observe that the low-Si 3 N 4 films are more sensitive to ionizing radiation than the high-Si 3 N 4 films. In particular, the low-Si 3 N 4 film that includes crystalline HfO 2 is especially vulnerable to electron trapping due to substrate injection under positive irradiation bias. Both film types exhibit reduced radiation-induced charge trapping relative to previous Hf silicates. The high-Si 3 N 4 film exhibits 16 less radiation-induced net oxide-trap charge density than earlier Hf silicate films processed without nitride. We also find that these devices are relatively robust against bias-temperature stress instabilities. Consistent with the radiation response, the low-Si 3 N 4 devices also display elevated levels of charge trapping relative to the high-Si 3 N 4 devices during bias-temperature stress.