Total ionizing dose effects of 60Co-γ ray radiation on SiC MOSFETs with different gate oxide thickness

Abstract

The application of SiC power devices in the space radiation environment not only requires good resistance to Single Event Effect (SEE) but also requires certain resistance to Total Ionizing Dose (TID) and long-term reliability. Increasing the thickness of the gate oxide layer (tox) can effectively improve the ability of SiC VDMOS to resist SEE. However, it will mainly impact its resistance to TID and Gate Oxide Integrity (GOI). Therefore, this paper compares the influence of tox on the radiation resistance and long-term reliability of SiC VDMOS under the same process and irradiation conditions. The experimental results show that after being irradiated by Cobalt-60 γ-rays, the static parameters of SiC VDMOS devices degrade severely with the increase of the tox; at the same time, the thick gate oxide process will also cause more defects in the gate oxide, leading to the decrease of the gate oxide long-term reliability, but it can be significantly improved after high temperature (HT) accelerated annealing. The research results suggest that the method of increasing tox should take into account the requirements of TID resistance and long-term reliability when improving the SEE radiation resistance of SiC VDMOS. This study is based on the improvement of electrical parameters and the analysis of reliability degradation of SiC VDMOS, providing experimental data support for determining the balance point of tox.