A Multiepi Superjunction MOSFET With a Lightly Doped MOS-Channel Diode for Improving Reverse Recovery

A multiepi (ME) superjunction (SJ) MOSFET with a lightly-doped MOS-channel diode (MCD) is studied by TCAD simulations. When the p-pillar is formed by the ME process, the resistance of the p-pillar can be much higher than that of a uniformly doped p-pillar, which helps to suppress reverse recovery oscillations of the body diode. Besides, by introducing the lightly doped MCD, electrons can easily flow from the n-pillar into the source contact when the body diode is in the on-state. Thus, the hole injection efficiency of the body diode can be lowered to reduce reverse recovery charge (Qrr) and further suppress reverse recovery oscillations. Simulation results show that the proposed SJ MOSFET is able to obtain a 64% lower Qrr and much lower reverse recovery oscillations than the conventional SJ MOSFET with a uniformly doped p-pillar.