Performance enhancement of 4H-SiC superjunction trench MOSFET with extended high-K dielectric

Abstract

This paper proposes a 4H-SiC superjunction trench MOSFET with extended high-K dielectric under metal gate (EHK SJ-TMOS). The characteristics of EHK SJ-TMOS include the use of the high-K (HK) dielectric as the gate dielectric and the extension of the HK dielectric as a deep trench into the N-type drift region. The extended HK trench effectively modulates the electric field distribution in the SJ drift region, which improves the breakdown voltage (BV). The introduction of HK dielectric also assists in depleting the SJ drift region, which enables the drift region of EHK SJ-TMOS to use a higher doping concentration, thereby reducing R_on,sp. Furthermore, the application of high-K gate dielectric alleviates the high gate oxide electric field problem in conventional SiC superjunction trench MOSFETs (SiC SJ-TMOS). The simulation results demonstrate that EHK SJ-TMOS exhibits a 59.2 % reduction in R_on,sp, a 2.4 % increase in BV, and a 156.5 % improvement in the FOM (FOM = BV²/R_on,sp) compared to the SiC SJ-TMOS, indicating enhanced performance.