A FIN-LDMOS with Bulk Electron Accumulation Effect.

A thin Silicon-On-Insulator (SOI) LDMOS with ultralow Specific On-Resistance ( R _on,sp ) is proposed, and the physical mechanism is investigated by Sentaurus. It features a FIN gate and an extended superjunction trench gate to obtain a Bulk Electron Accumulation (BEA) effect. The BEA consists of two p-regions and two integrated back-to-back diodes, then the gate potential V _GS is extended through the whole p-region. Additionally, the gate oxide W _oxide is inserted between the extended superjunction trench gate and N-drift. In the on-state, the 3D electron channel is produced at the P-well by the FIN gate, and the high-density electron accumulation layer formed in the drift region surface provides an extremely low-resistance current path, which dramatically decreases the R _on,sp and eases the dependence of R _on,sp on the drift doping concentration ( N _drift ). In the off-state, the two p-regions and N-drift deplete from each other through the gate oxide W _oxide like the conventional SJ. Meanwhile, the Extended Drain (ED) increases the interface charge and reduces the R _on,sp . The 3D simulation results show that the BV and R _on,sp are 314 V and 1.84 mΩ∙cm ^-2 , respectively. Consequently, the FOM is high, reaching up to 53.49 MW/cm ² , which breaks through the silicon limit of the RESURF.