Multifluid eulerian modelling of a silicon fluidized bed chemical vapor deposition process : analysis of various kinetic models

Abstract : Using the multifluid Eulerian code MFIX, the silicon Fluidized Bed Chemical Vapor Deposition process from silane (SiH4) has been modelled under transient conditions. In order to constitute an experimental database, a preliminary experimental study has been performed using a bed of Geldart’s group B particles. After a detailed analysis and comparison of the kinetic models available in the literature, four of them have been implemented in the MFIX code and two hydrodynamic models have been tested. 3-D simulations have shown that a strong interaction exists between the bed hydrodynamics, heat and reactive mass transfers and that Si deposition from silane mainly occurs in the dense zones of the bed whereas the unsaturated species silylene (SiH2) forms in bubbles and slugs and leads to Si deposition mainly at their periphery; its contribution to deposition can be locally as high as that of SiH4. The average contribution of SiH2 to deposition increases with the inlet concentration of silane and can reach 30%. The kinetic models derived from the law of Furusawa et al. and from the data compiled by Buss et al. and the hydrodynamic model based on the true granular energy equation and the Princeton solid phase stress model have revealed to be the most appropriate ones for the conditions tested.