SiC JBS二极管和SiC MOSFET的空间辐照效应及机理

Radiation effects of SiC JBS diodes and SiC MOSFETs

摘要:

基于第六代650 V 碳化硅结型肖特基二极管(SiC JBS Diode)和第三代900 V 碳化硅场效应晶体管(SiC MOSFET)，开展SiC功率器件的单粒子效应、总剂量效应和位移损伤效应研究。20~80 MeV质子单粒子效应实验中，SiC功率器件发生单粒子烧毁(SEB)时伴随着波浪形脉冲电流的产生，辐照后SEB器件的击穿特性完全丧失。SiC功率器件发生SEB时的累积质子注量随偏置电压的增大而减小。利用计算机辅助设计工具(TCAD)开展SiC MOSFET的单粒子效应仿真，结果表明，重离子从源极入射器件时，具有更短的SEB发生时间和更低的SEB阈值电压。栅-源拐角和衬底-外延层交界处为SiC MOSFET的SEB敏感区域，强电场强度和高电流密度的同时存在导致敏感区域产生过高的晶格温度。SiC MOSFET在栅压偏置(U_GS=3 V,U_DS=0 V)下开展钴源总剂量效应实验，相比于漏压偏置(U_GS=0 V,U_DS=300 V)和零压偏置(U_GS=U_DS=0 V)，出现更严重的电学性能退化。利用中带电压法分析发现，栅极偏置下氧化层内的垂直电场提升了陷阱电荷的生成率，加剧了阈值电压的退化。中子位移损伤会导致SiC JBS二极管的正向电流和反向电流减小。在漏极偏置下进行中子位移损伤效应实验，SiC MOSFET的电学性能退化最严重。该研究为空间用SiC器件的辐射效应机理及抗辐射加固研究提供了一定的参考和支撑。

Abstract:

Based on the sixth-generation 650 V SiC Junction Barrier Schottky(SiC JBS) diode and the third-generation 900 V Silicon Carbide Metal-Oxide Semiconductor Field-Effect-Transistor(SiC MOSFET), the single event effect, total dose effect and displacement damage effect of SiC power devices are studied. In the 20~80 MeV proton single event effect experiment, the Single Event Burnout (SEB) of SiC power device is accompanied by the generation of wave-shaped pulse current, and the breakdown characteristics of SEB devices are completely lost after irradiation. The accumulated proton fluence that induces SEB in SiC power devices decreases with the increase of bias voltage. In the single event effect simulation of SiC MOSFET, when heavy ions are incident on the device from the source, there exit a shorter SEB occurrence time and a lower SEB threshold voltage. The gate-source corner and the substrate-epitaxial layer junction are SEB sensitive regions of SiC MOSFET. The coexistence of strong electric field strength and high current density leads to excessive lattice temperature in the sensitive regions. When studying Co⁶⁰ source total dose effect for SiC MOSFETs at gate bias (U_GS=3 V, U_DS=0 V), more serious electrical characteristics degradation occurs compared to at drain bias(U_GS=0 V, U_DS=300 V) and zero voltage bias (U_GS=U_DS=0 V). Using the middle-band voltage method, it is found that the vertical electric field in the oxide layer under gate bias increases the generation rate of trapped charges and exacerbates the degradation of threshold voltage. The neutron displacement damage leads to the reduction of forward and reverse currents in SiC JBS diodes. The neutron displacement damage effect experiments are carried out under the drain bias, and the electrical characteristics of SiC MOSFET are degraded the most significantly. This work provides a certain reference and support for the research on the radiation effect mechanism and radiation hardening of SiC devices for space application.