State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology
Natural Science Foundation of Hubei Province (2020CFB806);Program for HUST Academic Frontier Youth Team (2019QYTD06).
为研究栅氧化物不同老化程度下,电子辐照对SiC MOSFET可靠性的影响,结合高温栅偏和电子辐照两种实验对SiC MOSFET电学特性进行了分析。讨论了栅氧化物受到高温和强电场应力后,电子辐照对SiC MOSFET阈值电压的影响。为避免封装材料在高温和电子辐照下对阈值电压产生影响,实验时将被测器件裸露在空气中。实验结果表明高温正栅偏后器件阈值电压对电子辐照更加敏感,提出了电子辐照对SiC MOSFET高温栅偏老化后阈值电压影响的指数关系,且0.2MeV电子能量辐照300kGy剂量可将39V 150℃ 2h高温栅偏后的器件阈值电压恢复至初始值。在Sentaurus TCAD仿真软件中建立了SiC MOSFET基础数值模型,设置氧化物内电子浓度和空穴陷阱,模拟高温栅偏和电子辐照对器件阈值电压的影响,讨论了阈值电压恢复机制。
To study the influence of electron irradiation on the reliability of SiC MOSFET with the different aging degrees of the gate oxide, the electrical characteristics of SiC MOSFET are studied by combining high-temperature gate bias and electron irradiation experiments. The influence of electron irradiation on the threshold voltage of SiC MOSFET after the gate oxide is stressed by the high temperature and the strong electric field is discussed. To avoid the impact of the packaging material on the threshold voltage under high temperature and electron irradiation environment, the device under test is exposed to the air during the experiment. The results show that the threshold voltage after the high-temperature positive gate bias experiment is more sensitive to electron irradiation. The exponential relationship of the influence of high-temperature gate bias and electron irradiation on the threshold voltage of SiC MOSFETs is proposed. The threshold voltage after the high-temperature gate bias at 39V and 150℃ for 2 hours can be restored to the initial value by 0.2MeV and 300kGy electron irradiation. The basic numerical model of SiC MOSFET is established in Sentaurus TCAD simulator. By setting the electron concentration and hole traps in the oxide, the effect of high-temperature gate bias and electron irradiation on the threshold voltage of the device is simulated. The threshold voltage recovery mechanism is discussed.