Improvement of Surge Current Capability in SBD-embedded SiC MOSFETs by Introducing Trigger p-n Diodes

In SBD-embedded SiC MOSFETs, we attempted to improve the surge current capability while suppressing the bipolar operation that causes long-term reliability problems. By incorporating trigger p-n diodes that induce conductivity modulation, we expected that higher current could flow with a low voltage and the surge current capability would be improved. The effectiveness of the trigger diode was confirmed by preliminary TCAD simulation, and SBD-embedded SiC MOSFETs with trigger diodes were fabricated. By placing SBDs in the trigger diode region at the same intervals as in the cell region, maximum current density without bipolar operation was maintained. By distributing 3 to 4 adjacent trigger diodes over the entire chip, the conductivity modulation and heat generation were spread out over the entire chip, and the surge current capability was improved by 1.43 times compared with an SBD-embedded SiC MOSFET without trigger diodes.