An Improved Composite JTE Termination Technique for Ultrahigh Voltage 4H-SiC Power Devices

This paper presents a novel and efficient multiple-step-modulated JTE (MSM-JTE) termination technique for ultrahigh voltage (>10 kV) silicon carbide (SiC) devices, to extend the ultrahigh voltage JTE dose window and increase the breakdown voltage. MSM-JTE takes advantage of ring assisted JTE, etched JTE and space modulated JTE, to relief local electric field concentration and form a gradual decrease of effective charges overall. This is similar to lateral variation doping (VLD) technique which is widely used in silicon. A practical fabrication processes is also described. Compared with conventional TZ-JTE, MSM-JTE requires only one extra etching process and is insensitive to doping dose and energy of ion implantation. The MSM-JTE is applied to 15 kV PiN rectifier and simulated by Silvaco TCAD. The simulation result shows MSM-JTE could reach a nearly ideal maximum efficiency of 99 % and keep an efficiency of 95 % in a doping interval of 7×1012 cm−2. Tolerance to etching depth uncertainties is also high enough for process reliability and repeatability.