Total ionizing dose effects on sub-100 nm gate-all-around MOSFETs

Abstract

The electric systems exposed to the radiation environment should have a special function, radiation-tolerance. Recently, multi-gate MOSFETs have been suggested as a next-generation for the radiation-hardening technique due to several disadvantages of enclosed-layout-MOSFETs, which is commonly used for the radiation-hardened circuits. However, the total ionizing dose (TID) effects, which are one of radiation effects, on the gate-all-around (GAA) MOSFETs is not investigated comprehensively. In particular, the TID effects on sub-100 nm GAA MOSFETs should be explored to utilize the strength of GAA MOSFETs and to apply the GAA MOSFETs for the radiation-hardened circuits. The TID effects on the sub-100 nm GAA MOSFETs down to 25 nm are investigated through the ex-periments and the numerical simulations. Particularly, the TID effects are explored for various gate lengths and radiation doses. The GAA MOSFETs have a strong radiation-tolerance compared to the double-gate MOSFETs because the GAA structure is favorable in respect to the TID effects. Additionally, the conspicuous relationship between the TID effects and the gate length is observed. A new hypothesis is suggested to explain the TID effects on the GAA MOSFETs. The suggested hy-pothesis assumes that the radiation-induced fixed charge and interface trap in the gate spacer mainly govern the TID effects on the GAA MOSFETs. The TID effects on the GAA MOSFETs are clearly explained by the suggested hypothesis. The hypothesis is experimentally examined by the junction modification of the GAA MOSFETs and supported by the three-dimensional numerical simulations. Through the verified hypothesis and the experimental data, the dominant roles of gate spacer and junction profile on the TID effects are demonstrated. The GAA MOSFETs have a supreme tolerance against the TID effects and excellent channel controllability. Consequently, the common problems of traditional radiation-hardening technique - limited immunity against the...