Investigation of Reverse Recovery Failure Mechanism in SJ MOSFET with Increasing Rg

We investigated the reverse recovery failure mechanisms in a 650 V -class Si superjunction (SJ) MOSFET with increasing gate resistance ($\boldsymbol{R}_{\boldsymbol{g}}$) by experiments and TCAD simulations. We analyzed that physical failure occurs when two phenomena take place simultaneously: voltage overshoot exceeding a critical value and non-uniform reverse recovery operation, meaning that reverse recovery at the edge termination is not completed even after reverse recovery at the active has terminated. As $R_{g}$ increases, the magnitude of overshoot increases due to the current imbalance between the drain-source capacitance, the parasitic inductance and a large gate delay of the device under test. This large overshoot eventually leads to device failures. This study confirms that the magnitude of overshoot depends on the electrical characteristics of the active rather than the edge termination, while the physical failure occurs on the edge termination area because the large current density and the voltage overshoot are applied due to the non-uniformity. Finally, we proposed strategies to develop the edge termination with improved resilience against physical failures in conditions with similar overshoot events.