Effect of overlap region for schottky metal and field oxide on the electrical characteristics of 6500 V/50A 4H-SiC JBS diodes

Abstract

The effect of overlap region for schottky metal and field oxide (ORSMFO) of field limiting rings termination on the reverse breakdown voltage of 6500 V/50A 4H-SiC JBS diodes was studied. Two comparative diodes were designed and fabricated. The reverse breakdown voltage of diodes with 20 μm ORSMFO improved significantly, which was up to 7000 V at the reverse leakage current of 10 μA and yield was up to 73 %. The structure simulation implied that the difference of the ORSMFO influenced the electric field strongly. Compared with the simulative terminal structure with 3 μm and 0 μm ORSMFO, the electric field intensity of the simulative terminal structure with 20 μm ORSMFO reduced by about 30 %-50 % near the main junction and the first three field rings.