SiC MOSFET with Integrated Zener Diode as an Asymmetric Bidirectional Voltage Clamp Between the Gate and Source for Overvoltage Protection

An integrated back-to-back SiC Zener diode is proposed and designed as an asymmetric bidirectional voltage clamp between the gate and source to protect the gate oxide of SiC MOSFET from the overvoltage stress. The leakage current of integrated SiC Zener diode is very low compared to conventional silicon poly Zener diode used for the same purpose and close to that of gate oxide, even at high temperatures. The pulsed current test shows that the overvoltage can be clamped by the integrated Zener and the characteristics of Zener integrated MOSFET did not degrade or change after continuous switching.