A novel split-gate trench MOSFET embedded with a high-k pillar for higher breakdown voltage

Abstract

A novel split-gate trench MOSFET embedded with a high-k pillar (HKP SGT-MOS) is proposed in this study. Numerous electric displacement lines are allowed to enter the high-k pillar introduced beneath the split gate, thus relieving the crowding of the electric field at the bottom corner of the split gate. Therefore, the HKP SGT-MOS can achieve a higher breakdown voltage (BV) without sacrificing its forward conduction. Various dielectrics for the high-k pillar, such as SiO2, Si3N4, Al2O3 and HfO2, are investigated. The results reveal that HfO2 has the largest figure of merit (FOM) and BV. The characteristics of the HKP SGT-MOS have also been validated by the Technology Computer-Aided Design simulation, and the BV and (FOM = BV 2/R on,sp) are 258.3 V and 37.46 MW cm−2, achieving 36.7% and 87.02% improvement compared to the conventional SGT-MOS (CSGT-MOS), and 18.4% and 38.59% improvement compared to the SGT-MOS with short split-gate (SSGT-MOS). Moreover, the influence of the drift doping concentration, the mesa width, the length of the drift region and the width of the split gate/high-k pillar are also studied to optimize the proposed HKP SGT-MOS.