An Ultralow Specific ON-Resistance LDMOST Using Charge Balance by Split p-Gate and n-Drift Regions

A laterally diffused metal-oxide-semiconductor transistor (LDMOST) with ultralow specific ON-resistance (R-sp) is studied. In the OFF-state, the split p-type gate is depleted to achieve charge compensation with the n-type drift region, allowing a high n-drift doping. In the ON-state, holes accumulate in the split p-gate because the gate voltage (V-G) applied induces simultaneously electron accumulation in the n-type drift region, enabling the on-current density to be not limited by the drift doping concentration and resulting in an ultralow value of R-sp. Moreover, the accumulated hole charges are stored in a capacitor during the turn-off process and are restored during the turn-on process, without an increase of the effective gate charge (Q(g)). Simulation results show good agreement with the theory. A 600 V device has an R-sp of <50% of the conventional double-RESURF LDMOST with the effective Q(g) being almost the same.