Gate Oxide Reliability of 4H-SiC V-Groove Trench MOSFET with Thick Bottom Oxide

Abstract

The authors reported the DMOSFETs fabricated on the 4H-SiC(0-33-8) in ECSCRM2012 and the novel V-groove MOSFETs, having (0-33-8) on the trench sidewall in ICSCRM2013. In this paper, we applied both the thick bottom oxide and the buried p+ regions to the V-groove MOSFETs for the protection of the trench bottom oxide. The V-groove MOSFET showed the low specific on-resistance of 3.2 mΩcm2 and the high blocking voltage of 1700 V on the bounty of the high channel mobility and the gate oxide protection, respectively. We also tested the gate oxide reliability of the V-groove MOSFET by constant-voltage stress TDDB measurement. The charge-to-breakdown was 18.0 C/cm2 at room temperature and 4.4 C/cm2 at 145°C. In addition, the stability of the threshold voltage was characterized with the VMOSFETs.