A Multiple-Ring-Modulated JTE Technique for 4H-SiC Power Device With Improved JTE-Dose Window

In this paper, a multiple-ring-modulated junction termination extension (MRM-JTE) technology for large-area silicon carbide PiN rectifier rated at 4500 V is proposed and experimentally investigated using a standard two-zone JTE (TZ-JTE) process without extra process steps or masks. Multiple modulation rings embedded inside JTE region, which is similar to varied lateral doping technology widely used in silicon devices, form a gradual decrease of effective charges in the termination region. MRM combines the advantages of two termination techniques, namely, ring-assisted JTE and space-modulated JTE, to enlarge the optimum JTE-dose window with high reverse blocking voltage in comparison with conventional TZ-JTE. A breakdown voltage of 4940 V at a leakage current of 1 μA is achieved from fabricated MRM-JTE rectifiers with a 36-μm-thick N-epilayer doped to 1.8 × 1015cm-3, which is 92% of the ideal parallel-plane value. A forward current of 50 A has been measured at a forward voltage drop of 3.9 V for devices with an active anode area of 9.2 mm2, corresponding to low differential on-resistance of 1.8 mQ · cm2. The simulation and experimental results show that the proposed device exhibits approximately 2 times JTE dose tolerance window improvement with respect to the breakdown voltage of 4500 V.