Effects of residence time and reaction conditions on the deposition of SiC from methyltrichlorosilane and hydrogen

The overall growth kinetics of silicon carbide films deposited from the mixture of methyltrichlorosilane (MTS) and hydrogen were determined by a magnetic suspension microbalance. The results show that three regions are distinguishable in the studied temperature range. In low temperatures (<1000°C), the deposition process is controlled by surface chemical reaction mechanism. The deposition rate has a weak dependence on temperature, and the activation energy is 188 kJ/mol. In mediate temperatures (1100°-1300°C), the deposition rate rapidly increases with increasing temperature, and the activation energy is 100 kJ/mol. The transition temperature of the above two deposition mechanisms lies in 1000°-1100°C. The complex relation between the deposition rate and total pressure can be explained by these two reaction mechanisms, depending on the competition between the residence time and concentrations of precursors. Both the flow rate and the distance into the chemical vapor deposition reactor strongly influence the reactivity. Longer residence time and larger distance of the substrate in reactor lead to decreasing deposition rate, mainly due to the reactant depletion on the wall, decomposition of MTS as well as the concentration of HCl.