Comparison between proton irradiated triple gate SOI TFETS and finfets from a TID point of view

Abstract

This paper compares, for the first time, the total ionizing dose degradation of 600 keV proton-irradiated silicon triple gate SOI tunnel FETs (TFETs) with SOI FinFETs fabricated with the same structure on the same wafer. This work is based on electrical measurements and TCAD simulations. Devices with different dimensions were exposed up to 10 Mrad(Si) dose of proton radiation. For transistors with narrow fin width, the radiation influence is negligible in both devices types. For WFIN = 250 nm and a proton radiation dose up to 10 Mrad(Si), on the other hand, a severe influence is observed in nFinFETs and pFinFETs present on the same die as the p-type TFETs. In the TFETs, no marked influence is observed. Only for a TFET of WFIN = 500 nm and 10 Mrad(Si) one can observe some radiation influence. The main degradation is caused by the buried oxide positive fixed charges and the interface traps which was also confirmed by TCAD simulations. The tunneling current of Tunnel-FETs presents a much better radiation hardness compared to the drift-diffusion current of SOI FinFETs.