Fin-Width Dependence of Ionizing Radiation-Induced Subthreshold-Swing Degradation in 100-nm-Gate-Length FinFETs

The dependence of the subthreshold-swing (SS) degradation on fin width is reported for irradiated 100-nm-gate-length, fully depleted n-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 I-d-V-gs curve is the composite of the 20 individual I-d-V-gs curves.