Silicon chemical vapor deposition from Si₂Cl₆ and Si₃ Cl₈

Si₂Cl₆ and Si₃Cl₈ were used as feed materials for silicon precipitation reaction. The precipitation reaction was conducted on non-crystalline quartz glass substrate in chemical control region using a horizontal cold wall reactor of atmospheric pressure at temperatures from 873 to 1273 K. The feed gas was diluted by hydrogen and/argon to 0.1 to 0.3 volume percent. The precipitation rate was measured under various experimental conditions of temperatures, feed concentrations and flow rates. The precipitate morphology was observed by X-ray diffraction analysis and SEM. The experimental precipitation rate was made of functions of temperature and feed concentration: i.e. in the surface reaction controlled region (873-1073 K), the rate dependence in Si₂Cl₆ -H₂-Ar system was proportional to 1/2 order of Si₂Cl₆ the former and to the first order of H₂. A plausible reaction mechanism is presented in which the reaction intermediate of SiCl₂ is employed. From the XRD and SEM results, those precipitated at 1073 K using either feed materials have preferred crystal orientation of (110) direction.