Investigations of inhomogeneous reverse recovery behavior of the body diode in superjunction MOSFET

This work provides a physical insight into the failure of Superjunction MOSFET (SJ-MOSFET) for full bridge inverter system during an reverse recovery behavior. The inspection of failed SJ-MOSFET reveals burnt-out points in the vicinity of the device edge termination. To explore this result, physical TCAD simulations have been carried out. It is found that there is an extremely inhomogeneous reverse recovery behavior between the active region and the termination region in the SJ-MOSFET. And a destructive dynamic avalanche phenomenon is occurred at the edge of the termination, which is identified as responsible for the observed failure. Finally, an optimization termination structure with P+ dynamical field limiting ring (DFLR) is proposed to suppress the dynamical avalanche and the reverse recovery robustness of the proposed structure is improved by 200%.