Fluidized bed silicon deposition from silane

An apparatus for producing silicon by thermally decomposing a silicon containing gas in the presence of fluidized nucleating seed particles of silicon comprising:

• a primary fluidized bed reactor defining a primary fluidized reactor zone;
• seed particle introduction means for introducing seed particles of silicon into said primary fluidized reactor zone;
• means for introducing a fluidizing gas into said primary fluidized reactor zone to maintain said silicon particles in a fluidized suspension;
• means for introducing a silicon containing gas into said primary fluidized reactor zone;
• means for heating said primary fluidized reactor zone to a temperature sufficient to thermally decompose the silicon in said silicon containing gas to elemental silicon for deposition on said silicon seed particles;
• means for removing excess fluidizing gas, unreacted silicon containing gas, reaction by-product gases and any entrained silicon particles therein from said primary fluidized reactor zone;
• means for removing silicon seed particles having thermally decomposed silicon product thereon from said primary fluidized reactor zone;
• and
• seed source means for supplying silicon seed particles to said seed particle introduction means, said seed source means including seed reactor means for thermally decomposing a seed generating gas containing silicon to form precursor silicon seed particles, said seed reactor having porous walls defining a pyrolysis seed reactor zone;
• means for introducing said seed generating gas containing silicon into said pyrolysis seed reactor zone;
• protective gas means for passing an inert gas through said porous reactor walls to provide a protective inert gas boundary to prevent deposition of silicon on said porous reactor walls;
• means for heating said pyrolysis seed reactor to a temperature sufficient to thermally decompose said seed generating gas containing silicon to form precursor silicon seed particles including a heat generating element disposed internally within said pyrolysis seed reactor zone and including means for providing a protective, inert gas boundary surrounding said heat generating element to prevent contact of silicon with said heat generating element;
• means for removing said precursor silicon seed particles from said pyrolysis seed reactor zone;
• and
• means for transporting said precursor silicon seed particles to said seed particle introduction means for introduction into said primary fluidized reactor zone as said silicon seed particles.