Ultra-Low On-Resistance LDMOS With Multi-Plane Electron Accumulation Layers

Abstract

An ultra-low specific ON-resistance ( ${R}_{\text {on,sp}}$ ) LDMOS is proposed and investigated by simulation in this letter. It features an extended tri-gate, a trench source, and a trench drain. in the on-state, multi-plane electron accumulation layers (MALs) and hence multiple ultra-low resistance current paths are formed along the bottom surface and side wall of the extended tri-gate. In the OFF-state, the extended gate assists in depleting the drift region and thus increases the doping concentration of the drift region ( ${N}_{d})$ . Both contribute to an ultralow ON-resistance. Moreover, the combined structure of the extended gate and tri-gate enhances the transconductance ( ${g}_{m})$ of the device. Additionally, the trench source and the trench drain shorten the current paths. As a consequence, both the current under the extended tri-gate and the total current increase. The performance of the MAL LDMOS is superior to that of the current state of art. Compared with the 70 V conventional LDMOS (Con. LDMOS) with the same dimension, the MAL LDMOS reduces the ${R}_{\text {on,sp}}$ by 90% and doubles the ${g}_{m}$ owing to the multi-plane accumulation layers. The MAL LDMOS maintains nearly the same breakdown voltage as the Con. LDMOS.