4H-and 6H-SiC MOSFETs fabricated on sloped sidewalls formed by molten KOH etching

Vertical 4H- and 6H-SiC MOSFETs have been fabricated on sloped sidewalls formed by molten KOH etching, which is expected to be free from the damage onto a channel region caused by a dry etching process. The slope angle could be controlled by adjusting etching temperature, and the anisotropy of inversion channel mobility was investigated. A higher inversion channel mobility and a lower threshold voltage were observed with increasing slope angle of channel region toward (1 (1) over bar 00) or (11 (2) over bar0). The highest mobility was 32 cm(2)/Vs for 6H-SiC, which is relatively high as an inversion channel mobility of UMOSFETs compared to previous works. The dependence of device performance on the slope angle and crystal orientation is discussed.