TRANSPORT OF DOPANT GAS DURING SILICON EP ITAXIAL THIN-FILM GROWTH INA HORIZONTAL REACTOR

Transport of dopant gas, B2H6 for p-type silicon epitaxial film growth is numerically calculated using the equation of B2H6 mass conservatio n for developing a model to predict the concentration distribution of B2H6 On a substrate in a cold-wall horizontal single-wafer epitaxial r eactor under a practical environment for preparing epitaxial silicon t hin-films. The B2H6 concentration is shown to be nonuniform over the s ubstrate surface, both stationary and rotating, because of a large the rmal diffusive flux of B2H6 induced by the horizontal and vertical tem perature gradients near the substrate, even when an uniform B2H6 conce ntration is imposed at the inlet of the epitaxial reactor. The ratio o f the thermal diffusive flux to the molecular diffusive flux in the re actor is also evaluated to show the larger relative effect of thermal diffusion to molecular diffusion for B2H6 than SiHCl3.