MODELING SILICON EPITAXIAL-GROWTH WITH SIH2CL2

Silicon epitaxial growth with SiH2Cl2 was modeled using measured SiH2Cl2 adsorption kinetics and H-2, HCl, and SiCl2 desorption kinetics from studies on Si(111) 7 x 7 surfaces. The predicted growth rates were compared with growth rates measured recently by Regolini et al. as a function of surface temperature between 923 and 1523 K. The agreement between the predicted and measured growth rates was very good. At lower temperatures between 923 and 1173 K, the silicon growth rates varied exponentially with temperature. The calculations revealed that HCl desorption is rate-limiting in this growth regime controlled by the availability of free surface sites. At temperatures above 1173 K, the silicon growth rates were proportional to the SiH2Cl2 pressure. This higher temperature region is controlled by the incident reactant flux and the reactive sticking coefficient of SiH2Cl2. The agreement between the calculations and measurements indicates that silicon epitaxial growth rates during low pressure chemical vapor deposition can be interpreted in terms of gas kinetic theory and adsorption and desorption surface kinetics.