A low on-resistance triple RESURF SOI LDMOS with planar and trench gate integration

A low on-resistance (R_on,sp) integrable silicon-on-insulator (SOI) n-channel lateral double-diffused metal-oxide-semiconductor (LDMOS) is proposed and its mechanism is investigated by simulation. The LDMOS has two features: the integration of a planar gate and an extended trench gate (double gates (DGs)); and a buried P-layer in the N-drift region, which forms a triple reduced surface field (RESURF) (TR) structure. The triple RESURF not only modulates the electric field distribution, but also increases N-drift doping, resulting in a reduced specific on-resistance (R_on,sp) and an improved breakdown voltage (BV) in the off-state. The DGs form dual conduction channels and, moreover, the extended trench gate widens the vertical conduction area, both of which further reduce the R_on,sp. The BV and R_on,sp are 328 V and 8.8 mΩ·cm², respectively, for a DG TR metal-oxide-semiconductor field-effect transistor (MOSFET) by simulation. Compared with a conventional SOI LDMOS, a DG TR MOSFET with the same dimensional device parameters as those of the DG TR MOSFET reduces R_on,sp by 59% and increases BV by 6%. The extended trench gate synchronously acts as an isolation trench between the high-voltage device and low-voltage circuitry in a high-voltage integrated circuit, thereby saving the chip area and simplifying the fabrication processes.