Simulation of silica deposition in an atmospheric pressure chemical vapour deposition reactor, using a modified CFD software

The deposition of silicon dioxide in an Atmospheric Pressure Chemical Vapour Deposition reactor from TEOS (tetraethoxysilane) and ozone mixtures has been studied and modelled, with the objective to optimise the productivity of an industrial equipment. ESTET, a French commercial CFD software, has been used to solve the hydrodynamic and heat transport problems. A subroutine has been developed to treat the mass transport and chemical reactions phenomena, both in the gas phase and on surfaces. A critical point being the stiffness of the chemical system, a specific model of the boundary layer type, has been developed to treat conveniently the numerical consequences of fast surface reactions, at the immediate vicinity of the substrate. Finally, the model is able to predict gas velocity, temperature and concentration profiles, then the deposition rate variations on the substrate surface; its systematic use has demonstrated that several regimes, corresponding to several rate limiting phenomena (species diffusion or chemical kinetics) must be distinguished. The results obtained are discussed and compared with experimental data.