J. Phys. IV France 03 (1993) C3-527-C3-533
Kinetic laws of the chemical process in the CVD of SiC ceramics from CH3SiCl3-H2 precursorF. LOUMAGNE1, F. LANGLAIS1 and R. NASLAIN2
1 Laboratoire des Composites Thermostructuraux, UMR 47, CNRS-SEP-UB1, Domaine Universitaire, 3 Allée de la Boétie, 33600 Pessac, France
2 Laboratoire des Composites Thermostrcturaux, UMR 47, CNRS-SEP-UB1, Domaine Universitaire, 3 Allée de la Boétie, 33600 Pessac, France
On the basis of growth rate measurements as a function of temperature and initial gas phase composition, the kinetic process of the CVD of silicon carbide from MTS-H2 is investigated, particularly under conditions of rate-control by the chemical reactions. Within specific ranges of dilution ratio 3 ≤ α ≤ 5 KPa and total pressure 3 ≤ P ≤ 10 KPa, two kinetic regimes are brought out depending on the temperature. At about 825°C, the deposition of SiC could be rate-limited by the homogeneous decomposition of MTS with an activation energy higher than 300 kJ.mol-1 and an apparent reaction order of 2.5 with respect to MTS. At about 925°C, surface reactions could control the overall kinetic process with an activation energy of only 160 kJ.mol-1 and an inhibitor chemisorption of Cl species which involves a negative reaction order with respect to HCl.
© EDP Sciences 1993