Films of $a-Si_{1-x}C_x$:H were prepared by thermally and RF glow discharge decomposition of silane-methane-gas mixtures. The characteristics of the bond structure, optical properties and resistivity were investigated as a function of the fraction of methane in the gas mixture and as a function of substrate temperature.
In thermally chemical vapor deposited a-SiC, it is suggested that the deposition temperature has a great effect on the bond structure, optical band gap and resistivity. It is also found that the bond structure is closely related to the optical band gap and resistivity.
In RF glow-discharge-deposited a-SiC, the optical properties and defect state depend strongly on the composition. According to the increase of composition parameter x, the main bond structure of a-SiC is changed from silicon bond structure to diamond and graphite bond structure. This change indi cates the increase of defect density and it has a great effect on the optical properties of a-SiC films.
For mathematical modeling and simulation study of horizontal type chemical vapor deposition reactor, thermodynamic equilibrim calculations, two dimensional mathmatical model of the fluid dynamics, and gas-phase kinetic reaction model were carried out for the prediction of film growth rate and film uniformity on the flow phenomena and other operating conditions. In order to solve 2-dimensional momentum, energy, and mass balance equations, finite volume numerical technique proposed by Spalding and Patankar was used. Gas phase kinetic model, which includes a 16-step elementary reaction mechanism in $SiH_4-H_2$ system and a 32-step in $SiH_4-CH_4-H_2$ system, is proposed for prediction of chemical species concentration profiles near substrate.
From these modelings, $SiH_2$ and $CH_3$ is the most important film precursor of the silicon carbide film in the pure silane and methane pyrolysis. For a high reaction rate, low flow rate or large temperature gradients increase film non-uniformity and at low total pressure uniformity is increased.
