KINETIC-STUDY OF SILICON PRECIPITATION FR OM SIHCL3

Using a hot-wall CVD reactor, silicon precipitation rates in the SiHCl 3-Ar and SiHCl3-H-2-Ar systems were measured in order to elucidate the reaction kinetics in these systems. Silicon precipitation in the form er system takes place through the thermal decomposition reaction of Si HCl3 and its rate is a function of reactant SiHCl3 mole fraction and r eaction temperature. That in the latter system takes place through the hydrogen reduction of SiHCl3 in addition to the thermal decomposition reaction and its rate can be expressed as a function of SiHCl3 and H- 2 mole fractions and temperature. In both systems, the transition temp erature from chemical reaction control region to mass transfer control region is around 1173 K. From the observed reactant concentration dep endence on these rate expression, a plausible reaction mechanism is pr oposed where SiCl2 (g) and its adsorbed species are the reaction inter mediate in the precipitation reaction scheme.