Low-temperature homoepitaxial growth of 4H–SiC with CH 3Cl and SiCl 4 precursors

Abstract

In prior research, a possibility to increase the growth rate of the low-temperature epitaxial growth of 4H–SiC was explored by supplementing chloro-carbon precursor CH 3Cl with HCl as an additional source of chlorine. In the current work, SiCl 4 was investigated as a replacement for SiH 4+HCl. The homogeneous nucleation in the gas phase was further reduced compared to SiH 4+HCl growth, thus essentially eliminating the main bottleneck for increasing the growth rate ( R g). However, for low values of the carrier gas flow, premature dissociation of Si gas-phase clusters was found to cause R g non-homogeneity and triangular defect formation. The drastically suppressed homogeneous nucleation opened the window for increasing the carrier gas flow velocity in order to improve the R g homogeneity from upstream to downstream. Nevertheless, generation of triangular defects was significant at R g above 5–6 μm/h. The process window for obtaining good epilayer morphology was found to correspond to Si supply-limited mode. The window was restricted at low values of C/Si ratio by formation of Si-rich islands/droplet and at high C/Si ratio by formation of polycrystalline SiC. The process window became increasingly narrower at higher R g, which serves as a new bottleneck for significantly increasing R g at such low growth temperatures.