Optimization of 1700V 4H-SiC Semi-Superjunction Schottky Diode with Multi-Step Trenched Structure

A novel 1700 V 4H-SiC semi-superjunction(SJ) Schottky diode have been designed and simulated in this study to alleviat the tradeoff dilemma between specific on resistance and blocking voltage in SiC power devices. The proposed multi-step trenched structure could be realized by the self- aligned process, and the p-pillars are then formed through vertical implantation into the bottom of the trenches. This practical and cost-effective fabrication method ensures controllable trench morphology and uniform p-doping below each level of trenches. Composed of a 4 μm SJ region above a 6 μm drift region, the optimized SiC semi-SJ have achieved a breakdown voltage above 2000 V with a specific on- resistance as low as 0.997 mΩ·cm ² , which breaks the theoretical 1-D limit of the SiC unipolar device. Furthermore, the proposed semi-SJ widens the implantation window by 37.5% compared to full-SJ, while realizing one order of magnitude lower leakage current due to the decreased surface electric field.