Orthogonal Positive-Bevel Termination for Chip-Size SiC Reverse Blocking Devices

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Abstract
Symmetric blocking power semiconductor switches require positive-bevel edge terminations for the reverse blocking p-n junction. This technique has been extensively applied to silicon wafer-size devices with high current ratings. In this letter, we propose and experimentally demonstrate, for the first time, that an orthogonal positive-bevel termination can be used for the reverse blocking junction of chip-size SiC devices. The edge termination was formed by sawing the SiC wafer with a V-shaped dicing blade. For proof of concept, our experiment was done on a SiC wafer with a 15.8-μm 6.1 × 10 15 cm -3 p-type epitaxial layer grown on an N + substrate. The positive-bevel termination resulted in a breakdown voltage of over 1000 V as limited by reach-through breakdown even without removal of damage from the sawing. The leakage current was found to be reduced by two orders of magnitude after reactive ion etching of the SiC bevel surface to remove the sawing damage.

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