Mechanisms of chemical vapor deposition of silicon

The distribution in the silicon epitaxial growth from SiCl₄ and hydrogen are observed in situ by IR absorption spectroscopy. Two methods are used complementarily, one is IR spectroscopy of reactants extracted from the reactor by a fine quartz tube which is not disturbing the reactions, and gives knowledge about the local distribution, the other is direct IR spectroscopy of hot reactants in the reactor which is useful to ascertain the results at the real high temperature situation. The intermediate species are SiHCl₃, SiH₂Cl₂ which is estimated from the induced emission bands at 500 and 570 cm^-1. HCl is a dominant waste product and contributes to reverse reactions. To investigate the reaction, HCl is intentionally injected into the reacting gas. This kind of injection method may also be very effective to analyze the reactions using other reactants such as SiCl₄, SiHCl₃ and SiH₂Cl₂.