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Modeling of Silicon CVD into Agglomerates of Sub-micrometer-size Particles in a Fluidized Bed

Authors

  • Nicolas Reuge,

    1. Laboratoire de Génie Chimique, UMR CNRS 5503, ENSIACET/INPT, University of Toulouse, 4 allée Emile Monso, BP 84234, 31432 Toulouse Cedex 4 (France)
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  • Brigitte Caussat

    Corresponding author
    1. Laboratoire de Génie Chimique, UMR CNRS 5503, ENSIACET/INPT, University of Toulouse, 4 allée Emile Monso, BP 84234, 31432 Toulouse Cedex 4 (France)
    • Laboratoire de Génie Chimique, UMR CNRS 5503, ENSIACET/INPT, University of Toulouse, 4 allée Emile Monso, BP 84234, 31432 Toulouse Cedex 4 (France)
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  • This work has been supported by the French Midi Pyrénées region council.

Abstract

The aim of the present study is to better understand the mechanisms involved during silicon deposition from silane, SiH4, into agglomerates of sub-micrometer-size particles treated by fluidized bed (FB)CVD. Two models of silicon deposition into agglomerates assumed either stable, or in permanent formation/desegregation, are developed. In the first case, classical equations of diffusion/reaction in a porous medium are solved, whereas in the second case, the multifluid Eulerian code, MFIX, is used. By comparison with experimental energy dispersive X-ray (EDX) data, modeling results show that the limiting step is not gaseous diffusion into the agglomerates. Very high local deposition rates near the silane entrance probably explain their formation. These results allow us to propose original deposition conditions involving much lower local deposition rates, which should limit agglomeration due to CVD.

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