100-V Class Two-step-oxide Field-Plate Trench MOSFET to Achieve Optimum RESURF Effect and Ultralow On-resistance

We propose a 100-V class two-step-oxide Field-Plate MOSFET (2-step FP-MOSFET), which is formed by two steps of thick-oxide to simplify the structure and fabrication process. By optimizing design parameters, we reveal the 2-step FP-MOSFET can achieve sufficient RESURF (Reduced Surface Field) effect and an ultralow specific on-resistance ( RONA). Measurement results showed breakdown voltage of 109.9 V and the RONA of 27.7 mohm·mm
²
with good process controllability. Moreover, as figure-of-merit of the 2-step FP-MOSFET, RON·Qg and RON·Qsw were reduced by 27.1% and 4.7%, respectively, compared with conventional one. Power loss estimation is also discussed by simple calculation.