Homoepitaxy of 4H-SiC on trenched (0001) Si face substrates by chemical vapor deposition

The homoepitaxy of 4H-SiC on trenched substrates by chemical vapor deposition has been investigated. Two types of 4H-SiC (0001) substrates inclined 8degrees toward [I IN] or [1100] were used. 4H-SiC growth near trenches perpendicular to the off-direction tended to be highly asymmetric due to the influence of step flow growth, and the (0001) facet was formed along the downstream side of trenches by step flow. In contrast, the growth near trenches parallel to the off-direction was symmetric. The strong influence of C/Si ratio on the growth behavior near trenches has been revealed. Although the growth rate on trench sidewalls is usually lower than that on the bottom of a trench and that on the top surface, this difference in epilayer thickness becomes smaller with decreasing C/Si ratio during growth. The use of a low C/Si ratio is effective in filling trenches. A smooth morphology was obtained on SiC substrates inclined toward the [ 1120] direction, but triangular surface defects appeared on SiC substrates inclined toward the [1100] direction.