Superjunction LDMOS with Dual Gate for Low On-Resistance and High Transconductance

Abstract

In this paper, a novel bulk silicon lateral superjunction double diffused MOSFET (SJ-LDMOS) with dual gate (DG) is proposed and its mechanism is investigated by numerical TCAD simulations. The proposed structure features the combination of a trench gate and a planar gate, forming two current conduction paths. One current conduction takes place along the highly doped N-pillar. The other is through the N-buffer layer ensuring uniform current distributions, which solves the problem of low conduction in the N-buffer layer of the SJ-LDMOS structures. The dual conduction paths improve the current uniformity through the entire SJ layer and the N-buffer layer, which effectively reduces the resistance of the device. Simulation results indicate that the proposed device is predicted to achieve a high breakdown voltage (BV) of 643 V and an extremely low specific ON-resistance (RONsp) of 28.53 mΩ· cm2, which is by 46.7 % lower than that of the previously N-buffer SJ-LDMOS structures with the same drift length. Besides, the transconductance of DG SJ-LDMOS is increased by 54.5 % and the figure of merit (FOM) on BV2/ RON,sp of DG SJ-LDMOS is increased by 85.5 %.