Plasma etching of silicon carbide trenches with high aspect ratio and rounded corners

Silicon carbide (SiC) is a representative third-generation semiconductor known for its superior properties, including a wide band gap, high electron saturation velocity, high thermal conductivity, and high physical/ chemical stability, making it highly promising for high-power electronic devices. In SiC power devices, superjunction architecture can reduce specific on-resistance without compromising breakdown voltage, while trenchgate structures provide better control over channel conductivity. In this work, we demonstrate high aspect ratio (>5:1) SiC trenches for superjunction devices and corner-rounded SiC trenches for gate trench power devices through plasma etching. The high aspect ratio trenches were achieved by optimizing the gas ratio in the etching process, and the corner-rounded trenches were directly formed by introducing nitrogen dilution during plasma etching. These results are significant for enhancing the performance of SiC trench-based power devices.