OPTIMUM PROCESS CONDITIONS FOR STABLE AND EFFECTIVE OPERATION OF A FLUIDIZED BED CVD REACTOR FOR POLYCRYSTALLINE SILICON PRODUCTION

The fluidized bed CVD process for the polycrystalline silicon production is considered to be the most attractive alternative to the conventional bell-jar process. The employment of a reaction path starting from monosilane has various merits over the conventional reaction path starting from trichlorosilane. In the present study, chemical vapor deposition of polycrystalline silicon on seed particles was conducted in a experimental fluidized bed reactor by thermal decomposition of monosilane diluted with hydrogen. The bed temperature was gradually increased and the conversion at the temperature was measured. The apparent first order reaction rate constant of monosilane pyrolysis in the bed was determined and the activation energy was found to be almost the same as that of heterogeneous deposition reaction rate constant. Optimum process conditions for stable and effective operation were determined. Lastly the continuous operation was conducted for more than 100 min. without any trouble and with the least fines elutriation under the optimum condition determined above