Patent ID: 9114996
Filing Date: 2015-08-25
Classification: B01J,C01B,F23C

Abstract:
1. A process for producing polycrystalline silicon by the thermal decomposition of silane in a fluidized bed reactor having a reaction chamber, the reaction chamber having a core region, a peripheral region and a cross-section through which feed gases pass, the fluidized bed reactor producing at least about 100 kg/hr of polycrystalline silicon per square meter of reaction chamber cross-section, the process comprising: introducing a first feed gas comprising silane into the core region of the reaction chamber, the reaction chamber containing silicon particles and the first feed gas containing less than about 80% by volume silane, wherein the temperature of the first feed gas is less than about 300° C. prior to entry into the reaction chamber; and wherein silane thermally decomposes in the reaction chamber to deposit an amount of silicon on the silicon particles; and introducing a second feed gas into the peripheral region of the reaction chamber, wherein the concentration of silane in the first feed gas exceeds the concentration in the second feed gas, wherein the temperature of the second feed gas is at least about 350° C. to about 600° C. prior to entry into the reaction chamber, the overall concentration of silane in the feed gases fed into the reaction chamber being less than about 15% by volume, the pressure in the reaction chamber being at least 15 bar.