Analysis of Leakage Current in SiC Power MOSFET Static Avalanche Breakdown based on Temperature-Dependent Simulation

The physical mechanism of the off-state avalanche breakdown process of SiC MOSFET which is composed of the active region and the termination region is analyzed by Sentaurus simulation and verified with TLP measurement data. At different stages of off-state, the current components of the active region and the termination region of SiC MOSFET are different, and a detailed explanation is given. The leakage current is generated by the presence of high impact ionization coefficients in the PN Junction of the transition region before the occurrence of the snapback. When the snapback occurs, electrons accumulate in the n-drift/n-substrate, while the previously generated large number of holes lowers the potential barrier of the n+-source/p-body to 0.13eV to form punch through current. The parasitic NPN bipolar transistor is not considered to be triggered for no continuous hole current injects into p-body. The termination region structure determined the avalanche breakdown voltage, and the active region decides the snapback current. TLP avalanche breakdown measurement indicates that the fabricated SiC MOSFETs with the same structure parameter as that utilized in the simulation shows the snapback phenomena, which verified the validity of the physical mechanism analysis of the off-state avalanche breakdown process.