The effect of input gas ratio on the growth behavior of chemical vapor deposited SiC films

Abstract

In an effort to protect a RBSC (reaction-bonded silicon carbide) reaction tube, SiC films were chemically vapor deposited on RBSC substrates. SiC films were prepared to investigate the effect of the input gas ratios (dilute ratio, α = PH2/PMTS = QH2/QMTS) on the growth behavior using MTS (metyltrichlorosilane, CH3SiCly3) as a source in hydrogen atmosphere. The growth rate of SiC films increased and then decreased with the decrease of the input gas ratio at the deposition temperature of 1250°C. The microstructure and preferred orientation of SiC films were changed with the input gas ratio; Granular type grain structure exhibited the preferred orientation of (111) plane in the high input gas ratio region (α = 3–10). Faceted columnar grain structure showed the preferred orientation of (220) plane at the low input gas ratios (α = 1–2). The growth behavior of CVD SiC films with the input gas ratio was correlated with the change of the deposition mechanism from surface kinetics to mass transfer.