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The silicon epitaxial growth behaviour was studied as an application of the parallel-Langmuir process using SiH2Cl2 gas and SiH3CH3 gas. The SiH3CH3 gas was used for in situ producing the SiHx gas by thermal decomposition in the reactor. With the increasing gas concentration of SiH3CH3, several results were obtained, such as (i) the silicon epitaxial growth rate increased exceeding the value saturated using the SiH2Cl2, (ii) the gas phase concentrations of the chlorosilanes at the exhaust decreased, (iii) the byproduct deposition at the exhaust decreased, and (iv) the gas phase concentration of HCl at the exhaust decreased. As a conclusion, the SiHx helped consuming the SiH2Cl2 gas for producing a silicon epitaxial film with reducing the byproduct deposition. Additionally, the SiHx might produce SiH2Cl2 in the gas phase by the reaction with the HCl gas.

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Effective process conditions to utilize a slim vertical silicon chemical vapour deposition reactor were studied. Based on a numerical analysis taking into account the gas flow, heat and species transport, particularly over a wide range of the trichlorosilane gas concentrations from 1% to 40 % in ambient hydrogen, a heavy and cold gas was shown to quickly go downward to the hot wafer surface through the slim vertical gas channel. The gas phase near the wafer was sufficiently cooled to produce a cold wall thermal condition which enabled the trichlorosilane gas consumption only at the wafer surface, even in a non-axisymmetric and non-steady condition. The slow wafer rotation, less than 30 rpm, had a considerable effect, such as that increasing the gas phase temperature gradient for suppressing the gas phase reaction.

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