Production of high-purity granular silicon by thermal decomposition of silanes or halosilanes in a fluidized-bed reactor comprises separating particles of the desired size in an external classifier

摘要

Production of high-purity granular silicon comprises thermal decomposition of silanes or halosilanes in a gas stream flowing upwards through a fluidized bed of seed particles in a reactor connected to an external classifier in which particles of the desired size are separated. An Independent claim is also included for a fluidized-bed reactor comprising a reaction chamber (4) equipped with a reactant gas inlet (1), a baffle plate (2) and a perforated plate (3); a heater (5) surrounding the reaction chamber; a barrier gas inlet (6) opening into an annular chamber (8) surrounding an outlet (7) with drive jet orifices; a classifier pipe (10) connected to the outlet and equipped with a classifying gas inlet (9), a product outlet valve (15) and a collection vessel (16); a fines recycle system located above the classifier pipe and comprising a cyclone (12) and a flap valve (13); a dust discharge pipe (14); and a seed material inlet (17).