The Influence of Total Dose Irradiation and Annealing Experiments on Three Types of SiC Power Devices

SiC MOSFETs have gained widespread application and attention due to their superior performance, but their reliability is still a problem that must be solved in application. This work focuses on the characterization test and analysis of main electrical characteristics and defect changes of SiC VDMOS with three structures before and after total dose irradiation and annealing recovery experiment. The experimental results show that the electron-hole pairs generated by
⁶⁰
Co-γ rays inside the devices generate interfacial state traps at the SiO
2
/Si interface of the gate oxygen layer, and the charge formed by the holes captured by these interfacial state traps at the SiO
2
/Si interface causes the threshold voltage of the devices negative drift. The double trench device is most affected by the total dose irradiation experiment, with the most significant changes in threshold voltage, saturation drain current, and number of defects, followed by the asymmetric trench device, and the least change in the planar gate device. The characteristics of the asymmetric trench and planar gate devices basically recovered after room-temperature and high-temperature annealing, while the double trench device was still severely degraded. Analysis is due to the immaturity of etching and oxidation processes in trench gate structure devices, which leads to the poorer radiation resistance of the SiO
2
/SiC interface at the gate oxide layer compared to the planar gate. While the asymmetric trench structure protects the trench gate oxide layer by forming a P+ region under the gate slot through ion injection, which can alleviate the problem of poor radiation resistance of the trench gate structure to some extent.