The effect of diluent gases on the growth behavior of CVD SiC films with temperature

Silicon carbide films have been grown onto graphite substrates by low press ure chemical vapor deposition using MTS (CH3SiCl3) as a source precursor an d H-2 or N-2 as a diluent gas. The experiments were performed at fixed cond itions of a flow rate of 100 sccm for each MTS and carrier gas, a flow rate of 300 sccm for diluent gas addition, and a total pressure of 5 torr. The effect of temperature from 900 degrees C to 1350 degrees C and the alterati on of diluent gas species on the growth rate and structure of deposits have been studied. The experimental results showed that the deposition rate inc reased with increasing deposition temperature irrespective of diluent gases and reactant depletion effect increased especially at H-2 diluent gas ambi ent. At MTS-H-2 system, the deposition mechanism changed from chemical reac tion to mass transfer controlled reaction with temperature. Otherwise, For MTS-H-2-N-2 system, surface chemical reaction controlled the growth process at whole deposition temperature ranges. For N-2 addition, surface morpholo gy of leaf-like structure appeared, and for H-2, faceted structure at 1350 degrees C. The observed features were involved by crystalline phase of beta -SiC and surface composition with different gas ambient. (C) 2000 Kluwer Ac ademic Publishers.