Very high growth rate of 4H-SiC epilayers using the chlorinated precursor methyltrichlorosilane (MTS)

Abstract

The chlorinated precursor methyltrichlorosilane (MTS), CH 3SiCl 3, has been used to grow epitaxial layers of 4H-SiC in a hot wall chemical vapour deposition (CVD) reactor with growth rates higher than 100 μm/h. The addition of chlorinated species to the gas mixture prevents silicon nucleation in the gas phase, thus allowing higher input flows of the precursors resulting in much higher growth rate than that of standard silicon carbide (SiC) epitaxial growth using only silane, SiH 4, and hydrocarbons as precursors. Since MTS contains both silicon and carbon, with the C/Si ratio 1, MTS was used both as single precursor and mixed with silane or ethylene to study the effect of the C/Si and Cl/Si ratios on growth rate, morphology, and doping of the epitaxial layers. When using only MTS as precursor, the growth rate showed a linear dependence on the MTS molar fraction in the reactor. The growth rate dropped for C/Si<1 but was constant for C/Si>1. Further, the growth rate decreased with lower Cl/Si ratio. This study shows that MTS is a promising precursor for homoepitaxial growth of SiC within the concept of chloride-based SiC growth.