Reliability Mechanism Of SiC Power MOSFET Based On Low-frequency Noise Theory

Silicon carbide（SiC）is one of the most popular semiconductor materials due to its excellent performance.SiC devices have been widely adopted in high-power applications.With the continuous development of materials and manufacturing technology,commercial SiC power MOSFET modules have been able to sustain a rating voltage up to 1700 V in recent years.However,reliability issues need to be addressed although it is difficult.In this article,the degradation behavior of the commercial SiC power MOSFETs was investigated under repetitive accelerated stress,and defect analysis based on low-frequency noise（LFN）was carried out.The experimental results show that increasing power-cycling stress results in a forward shift of threshold voltage and increasing on-resistance.Meanwhile,the drain-to-source current significantly decreases with the increase of the cycles.Furthermore,the gate–source leakage current(I_gss)of the device became larger and the blocking characteristics deteriorated after 10-k cycles.The negative shift of the gate-capacitance versus gate-voltage（C-V）curve was analyzed.Trap characterization was performed by using the LFN method,and it was found that the trap density of the device increased 5.47 times after 10-k cycles.The short-circuit current test results show that the threshold voltage and on-resistance of the device have a tendency of increasing,and the I_gss has a significant increase.The C-V curve shows a positive shift in the inversion area,and the blocking characteristic is obviously degraded.Furthermore,the trap density of the device was analyzed with the LFN theory and model.The trap density has increased 9.21 times after 800 cycles.Finally,the physical mechanism of the degradation for SiC power MOSFET was investigated under accelerated stress.The results show that interface traps in the SiC channel below the SiC/SiO₂ interface are the main sources of 1/f noise in the device.The degradation mechanism could be attributed to electrically active trapped charges generated at the SiC/SiO₂ interface during accelerated stress.