Design and Fabrication of 1.2kV SBD Integrated 4HSiC MOSFET for Reliable Reverse Conduction

This work investigated the integration of Schottky barrier diode (SBD) into SiC MOSFET to address the severe bipolar degradation issue caused by the bipolar conduction through the SiC MOSFET body diode. The impact of key structure parameters on the device performance is studied through numerical simulations. An optimum Schottky contact length is then chosen for fabrication. The fabricated device demonstrates a blocking voltage over 1350V. The conduction ONresistance is 300mΩ. With Titanium as the source Schottky metal, the reverse turn-on voltage of the SiC MOSFET is below 1V, which is 3 times lower than that of the conventional SiC MOSFET. More importantly, with such an integrated SBD, the reverse conduction can be achieved with only unipolar current. Therefore, the bipolar degradation can be prevented to improve long term reliability.