Degeneration mechanism of 30 MeV and 100 MeV proton irradiation effects on 1.2 kV SiC MOSFETs

Abstract

In this study, we evaluated and characterized the effects of various proton irradiation energies and fluences on the electrical characteristics of SiC MOSFETs using a proton accelerator. The devices under test (DUTs) were fabricated utilizing 1.2 kV SiC MOSFET processes. To assess the impact of total ionizing dose (TID) and displacement damage (DD) on SiC MOSFETs, the DUTs were exposed to protons irradiation at energies of 30 MeV and 100 MeV, under ambient temperature conditions. Additionally, we examined the radiation hardness of DUTs under varying proton fluences, including 1 × 10¹² cm⁻², 1 × 10¹³ cm⁻², 5 × 10¹³ cm⁻², and 1 × 10¹⁴ cm⁻².

The results demonstrate that the threshold voltage (V_th) of the irradiated devices exhibited a negative shift, attributable to radiation-induced positive oxide trapped charges. This negative shift in V_th, coupled with the accumulation of positive trapped charges in the field limiting ring (FLR) oxide, resulted in augmented output currents and diminished breakdown voltage (BV) values. A significant reduction in current, ranging from 70% to 99%, was observed in the DUT subjected to irradiation at of 30 MeV and 1 × 10¹⁴ cm⁻², highlighting the influence of DD. Conversely, irradiation at 100 MeV primarily revealed TID effects, characterized by a negatively shifted V_th. The on-state current at a gate voltage of 10 V and a drain voltage of 5 V of the DUT with irradiation of 100 MeV and 1 × 10¹⁴ cm⁻² was a higher than that of DUT without irradiation because of a reduction of V_th.