EFFECTS OF THERMAL DIFFUSION AND SUBSTRATE TEMPERATURE ON SILICON DEPOSITION IN AN IMPINGING-JET CVD REACTOR

A numerical/computational model and the associated FORTRAN computer code have been developed to simulate the chemical vapor deposition processes. The model includes variable fluid properties and buoyancy forces in the hydrodynamic model and does not use Bousinesq approximation. The model is applied to predict the silicon deposition rate from gaseous silane supplied with a hydrogen carrier gas in an atmospheric-pressure circular impinging-jet reactor. A wide range of wafer temperature (933-1733 K) with three different silane inlet mass fractions is investigated. The significance of the thermal diffusion or Soret effect on the silicon deposition rate is also conducted. Grid-independent solutions are obtained. It is found that while the deposition rate increases greatly with the wafer temperature, the silane inlet mass fraction does not have a significant effect. Small changes in the deposition rates, along with very small thermal diffusion ratios, are observed if the Soret effect is included in the model. Thus, the Soret effect is found to be negligible for this reactor configuration over the range of wafer temperatures and silane inlet concentrations investigated.