Superjunction MOSFET With Dual Built-In Schottky Diodes for Fast Reverse Recovery: A Numerical Simulation Study

A new superjunction MOSFET (SJ-MOSFET) architecture with dual built-in Schottky diodes is proposed and studied with the numerical TCAD simulations. This letter is based on silicon. One Schottky contact is formed at the top of the n-pillar, while the other is formed at the bottom of the p-pillar. During the reverse conduction period, the Schottky junctions turn on at a lower voltage than the PN junction. The current flows through n-pillar and p-pillar in parallel, so the potential difference across the PN junction is kept below its turn-on voltage. Thus, minority carrier injection through the PN junction is completely suppressed, leading to a superior reverse recovery performance. Integration of a single Schottky contact to either the n-pillar or the p-pillar cannot completely suppress the turn-on of the PN junction in the SJ-MOSFET due to the potential drop created by the current through only one type of the pillars. Furthermore, the proposed dual-Schottky SJ-MOSFET reduces the gate charge (QG) and the gate-to-drain charge (QGD), compared with the conventional SJ-MOSFET, leading to better figures of merit.