Modeling particle growth and deposition in a tubular CVD reactor

• Published in: Journal of crystal growth 1999-04, Vol.200 (3), p.527-542
• Main Authors: Lu, Shih-Yuan, Lin, Hway-Chi, Lin, Chung-Hong
• Format: Article
• Language: English
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Cross-disciplinary physics: materials science; rheology; CVD; Deposition; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Particle growth; Physics; Theory and models of film growth; TiO 2
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/S0022-0248(99)00041-X

A computational model is developed to simulate the particle formation, growth, and deposition in a tubular CVD reactor. The model takes into account the momentum, heat, and mass transfers, chemical reaction, Brownian coagulation, Brownian diffusion, thermal diffusion, and thermophoresis that occur within the reactor. The chemical system is illustrated by the formation of TiO 2 particles through oxidation of TiCl 4. A set of coupled partial differential equations is solved with the finite volume method to give spatial distributions of velocities, pressure, temperature, TiCl 4 concentration, and sizes of TiO 2 particles, from which the deposition mass fluxes and size distributions of exit TiO 2 particles can be readily evaluated. In the model, the growth of particles is simulated by the discrete-sectional model, which can cover particle growth from monomers up to the submicron size. Among other things, the simulation predicts a maximum deposition flux near the reactor entrance and a rebound in deposition flux near the reactor exit, which have been observed in several experimental studies. The model also reveals a delay in evolution of size distribution near the reactor wall as compared to that of the bulk. This delay signifies that the size distribution of depositing particles at the wall is in general different from that of the bulk, which normally is the measured one. The effects of important operating parameters such as temperature, pressure, inlet TiCl 4 concentration, and inlet stream velocity on various system performance indicators are also investigated.