Preliminary study of a radiantly heated bed for the production of high-purity silicon

This article describes the exploration of a processing method which uses radiant heating of the particles of a fluidized bed for the production of high-purity silicon. The process involves heating the particles at the surface of a shallow fluidized bed by radiant heaters located above the surface of the bed. The radiant sources could be cooled by a purge of inert gas which is exhausted with the spent H2. The hot bed particles would circulate down to the bottom of the bed where they would heat the cold silane gas rising through the distributor plate. Decomposition and deposition of the silane then follow. Two important characteristics of the system are discussed. One is the ''effective absorptivity'' of the bed. This is the fraction of electrical energy supplied to the heaters which is actually absorbed by the particles. The other is the heat transfer coefficient between hot bed and cool distributor plate. Knowledge of this will allow prediction of the temperature of the distributor plate during silicon production.