THERMAL AND KINETIC MODELING OF LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION HOT-WALL TUBULAR REACTORS

A mathematical model, describing the complete behaviour of low-pressure chemical vapour deposition (LPCVD) reactors has been developed. The improvement of this model over existing ones reported in the literature consists in that it gives a more detailed account of the temperature profile on the solid surfaces in an LPCVD reactor. On the other hand, the proposed model is considerably simpler than most others already proposed, since it utilizes a continuously stirred tank reactor approach for mass balances. This approximation makes the model only relevant but, nevertheless, particularly useful to the case of depositions naturally leading to uniform layers across each wafer and, therefore, to the case of pure polycrystalline deposition from silane. A systematic use of this model, combined with a comparison of its predictions with experimental data, has served as an incentive for further investigations of other chemical vapour deposition systems (in situ boron-doped polysilicon and semi-insulating polyoxide silicon depositions) and is of interest for the choice of new industrial processes.