Patent attributes
The invention relates to a method for producing polycrystalline silicon granulate in a fluidized bed reactor. The method comprises a fluidization of silicon seed particles by means of a fluidizing gas in a fluidized bed, which is heated by a heating device, wherein elemental silicon is deposited by pyrolysis on the silicon seed particles by the addition of a reaction gas containing hydrogen and silane and/or halosilane to form the polycrystalline silicon granulate. In a continuous process, waste gas is discharged from the fluidized bed reactor and hydrogen recovered from said waste to gas is again supplied to the fluidized bed reactor as a circulating gas. The circulating gas has a nitrogen content of less than 1000 ppmv. The invention further relates to polycrystalline silicon granulate having a nitrogen content of less than 2 ppba.
