Influence of forward current freewheeling time on di/dt robustness of SJ-MOSFET body diode

The influence of forward current freewheeling time on the reverse recovery di/dt robustness of Superjunction (SJ) MOSFET body diode is investigated in detail. It is found that the maximum di/dt capability of body diode is improved dramatically with reducing the forward current freewheeling time. To explore this phenomenon, physical TCAD simulations and experiments have been carried out. It shows that there is an extremely inhomogeneous reverse recovery behavior between the cell region and the termination region in the SJ-MOSFET, which results in a destructive dynamic avalanche behavior at the edge of the termination. The reduction of the forward current freewheeling time can suppress the inhomogeneous phenomenon and impact the reverse recovery di/dt robustness of body diode. Thereby, it points out that the real di/dt robustness of SJ-MOSFET body diode should be evaluated with the long enough forward current freewheeling time.