Effect of Surface Roughness of Trench Sidewalls on Channel Mobility in 4H-SiC Trench MOSFETs

Abstract The effect of the surface roughness of trench sidewalls on electrical properties have been investigated for improving channel mobility in 4H-SiC trench MOSFETs. The surface roughness was evaluated by atomic force microscopy (AFM). The characteristics of channel mobility were analyzed based on the mobility model including optical phonon scattering. The results revealed that surface roughness scattering had small contribution to channel mobility, and there was no correlation between the experimental RMS values and surface roughness scattering. On the other hand, it was necessary to pay attention to the surface morphology from the view point of device reliability.