Fabrication of self-aligned graded junction termination extensions with applications to 4H-SiC P-N diodes

The properties of SiC make this wide band-gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices, such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc., all of which require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power-handling capabilities. In this paper, we describe a technique for fabricating a graded junction termination extension (GJTE) that is effective and self-aligned, a feature that simplifies the implantation process during fabrication and, therefore, has the potential to reduce production costs. Implanted anode p-n diodes fabricated using this technique on 10-μm thick n⁻ epitaxial layer had a maximum breakdown voltage of 1830 V. This was comparable to the ideal parallel-plane breakdown of 1900 V predicted by numerical simulation.