A Superjunction MOSFET with Self-Adjustable Electron Path for Low Reverse Recovery Charge

A novel superjunction MOSFET (SJ-MOSFET) with self-adjustable electron path (SEP) is proposed. The SEP is formed by a floating ohmic contact (FOC) and two parasitic diodes. In the off-state, the SEP is depleted by two parasitic diodes, suppressing increment of leakage current. In the forward on-state, the SEP equalizes electrostatic potential of the N-Pillar and the P-Pillar by the FOC, without increasing specific on-resistance. In the reverse on-state, the SEP achieves conversion between electrons and holes by the FOC, reducing minority carrier current and minority carrier injection. By TCAD simulation, during reverse recovery, the proposed structure achieves 40.8% reduction in peak reverse recovery current $I_{\text{rrm}}$, 60.1% reduction in reverse recovery charge $Q_{\mathrm{r}\mathrm{r}}$ and 45.7^% improvement in softness factor $S$, improving reverse recovery characteristics without deterioration of other electrical characteristics.