Influence of Drain Bias and Flux on Heavy Ion-Induced Leakage Currents in SiC Power MOSFETs

Radiation-induced leakage current degradations for SiC power MOSFETs are investigated by181Ta ion irradiation. An ion flux-related leakage degradation is reported for the first time. It is manifested as a more significant leakage current under higher flux irradiation than that under low flux irradiation, even though the total fluence is the same. Emission microscope (EMMI) results show that more leakage paths are formed for high flux irradiation. The drain bias during irradiation is another key fact to affect the radiation-induced leakage degradation. The leakage only occurs when the drain bias is larger than 300 V for flux = 1000/cm²· sirradiation. An interesting phenomenon is that although radiation-induced leakage is not observed at 200 V with ion flux of 1000/cm²· s, leakage appears when the ion flux increases to 6000/cm²· s. A multi-ion interaction theory is proposed to explain the above phenomenon. The mechanisms of these phenomena are also proved by TCAD simulations.