Chloride-based fast homoepitaxial growth of 4H-SiC films in a vertical hot-wall CVD

摘要

Chloride-based fast homoepitaxial growth of 4H-SiC epilayers was performed on 4° off-axis 4H-SiC substrates in a home-made vertical hot-wall chemical vapor deposition (CVD) system using H2–SiH_4–C_2H_4–HCl. The effect of the SiH_4/H_2 ratio and reactor pressure on the growth rate of 4H-SiC epilayers has been studied successively. The growth rate increase in proportion to the SiH_4/H_2 ratio and the influence mechanism of chlorine has been investigated. With the reactor pressure increasing from 40 to 100 Torr, the growth rate increased to 52 μm/h and then decreased to 47 μm/h, which is due to the joint effect of H_2 and HCl etching as well as the formation of Si clusters at higher reactor pressure. The surface root mean square (RMS) roughness keeps around 1 nm with the growth rate increasing to 49 μm/h. The scanning electron microscope (SEM), Raman spectroscopy and X-ray diffraction (XRD) demonstrate that 96.7 μm thick 4H-SiC layers of good uniformity in thickness and doping with high crystal quality can be achieved. These results prove that chloride-based fast epitaxy is an advanced growth technique for 4H-SiC homoepitaxy.