Grayscale Junction Termination for High-Voltage SiC Devices

Abstract

In silicon carbide devices used above around 2.4 kV, effective anode edge termination usually requires a high-resolution floating guard ring implant or multiple lithography/implant cycles to effect a multi-zone junction termination extension. In general the goal is to produce a smoothly tapered field profile to prevent high-voltage field-crowding that causes premature breakdown at the edge of the high voltage electrode. Using a much simpler grayscale photolithographic technique and a single termination implant, we directly produce the desired tapered doping profile. The effectiveness of this termination is shown by the near-ideal (6.1 kV) breakdown measured in PiN diodes made with a 38 µm intrinsic layer. The simple method is applicable to the fabrication of many high-voltage devices.