Epitaxial Growth of 4H-SiC on (000-1) C-Face Substrates by Cold-Wall and Hot-Wall Chemical Vapor Deposition

Epitaxial layers have been grown on the (0001) C-face of 2- and 3-inch 4H-SiC wafers. Growth conditions like temperature, pressure, and C/Si ratio have been varied. In both systems smooth surface morphologies could be obtained. The main challenge of epitaxial growth on the Cface of 4H-SiC for electronic device applications seems to be the control of low doping concentration. High temperature and low pressure are the key parameters to reduce the nitrogen incorporation. The hot-wall CVD system used for these experiments allowed the application of higher temperatures and lower pressures than the cold-wall equipment. The lowest doping concentration of 2.5x1015 cm-3 has been achieved by hot-wall epitaxy using a temperature of 1625 °C, a system pressure of 50 hPa, a C/Si ratio of 1.4, and a growth rate of 6.5 2mh-1. Good doping homogeneity on 2-inch and 3-inch wafers could be achieved. For a doping level of ND-NA= 3×1015 cm-3 sigma is about 15%.