NUMERICAL-SIMULATION OF MONOSILANE CONVER SION AND FINE ELUTRIATION IN POLYCRYSTALLINE SILICON PARTICLE-PRODUCTION VIA FLUIDIZED-BED CVD

Numerical simulation of polycrystalline silicon particle production by fluidized bed CVD using monosilane is carried out. The model consists of a Kunii-Levenspiel fluidized bed model and reaction kinetics of mo nosilane pyrolysis in the free space and on particles. Conversion of m onosilane, conversion to fines (fines elutriation), and vertical tempe rature profile in the bubble are calculated using the present model. E ffects of scavenging of the fines, deposition on the fines and the tem perature profile on the conversions are discussed. The numerical resul ts are compared with the experimental results of Hsu et al,. The numer ical results of the conversions in the case of deposition on the fines are larger than those without deposition, while other factors give lo wer conversions. Consideration of deposition on the fines is found to be essential to explain the experimental results. The diameter of seco ndary particles of fines agglomerates should be taken into account as a function of bed temperature, It is suggested that the experimentally observed effect of the bed temperature on the fines elutriation is po ssibly explained when the degree of scavenging or the diameter of seco ndary particles is increased with increasing bed temperature, both of which are caused by the increase in fines' adhesivity with temperature .