High-voltage UMOSFETs in 4H SiC

We report the design and fabrication of UMOSFETs on 4H-SiC with specific on-resistances of 105.1 mΩ cm² at a current density of 100 A/cm² and blocking voltage of 5,050 V. These devices incorporate an extended self-aligned p-bottom implant to protect the gate oxide from high electric fields. A novel shadow implant mask was developed to shield the sidewalls from any unwanted p-bottom implant. These UMOSFETs are also the first to incorporate a post-oxidation anneal (POA) in nitric oxide (NO) to improve the inversion layer electron mobility. A single zone JTE (junction termination extension) with peak blocking voltage of 7,500 V was implemented in the device design.