A submicron sized Si based powder having an average primary particle size between 20 nm and 200 nm, wherein the powder has a surface layer comprising SiO.sub.x, with 0<x<2, the surface layer having an average thickness between 0.5 nm and 10 nm, and wherein the powder has a total oxygen content equal or less than 3% by weight at room temperature. The method for making the powder comprises a step where a Si precursor is vaporized in a gas stream at high temperature, after which the gas stream is quenched to obtain Si particles, and the Si particles are quenched at low temperature in an oxygen containing gas.

A method for manufacturing polysilicon, according to the present invention, is capable of manufacturing polysilicon with high purity more efficiently in such a manner that a high-temperature and high-speed air stream is formed at the center of a reaction tube, and a high-temperature region may be formed by a vortex formed by the high-temperature and high-speed air stream, so that a raw gas supplied from the side wall of the reaction tube flows by the guiding of the vortex, thereby increasing a stay time and a reaction time of the raw gas within the reaction tube. Furthermore, since the inner wall of the reaction tube is provided with a heat release means, the rapid cooling of a silicon crystal deposited on the inner wall of the reaction tube can induce a columnar crystal in which the silicon crystal is solidified in a direction perpendicular to a crystal face, and it is easy to desorb the silicon crystal produced by rapid heat release via the inner wall of the reaction tube.

A method for manufacturing polysilicon, according to the present invention, is capable of manufacturing polysilicon with high purity more efficiently in such a manner that a high-temperature and high-speed air stream is formed at the center of a reaction tube, and a high-temperature region may be formed by a vortex formed by the high-temperature and high-speed air stream, so that a raw gas supplied from the side wall of the reaction tube flows by the guiding of the vortex, thereby increasing a stay time and a reaction time of the raw gas within the reaction tube. Furthermore, since the inner wall of the reaction tube is provided with a heat release means, the rapid cooling of a silicon crystal deposited on the inner wall of the reaction tube can induce a columnar crystal in which the silicon crystal is solidified in a direction perpendicular to a crystal face, and it is easy to desorb the silicon crystal produced by rapid heat release via the inner wall of the reaction tube.

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.

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.

Contamination of fluidized bed-produced polycrystalline granules by phosphorus is reduced by employing as seals and/or packings, graphite containing <500 ppmw of phosphorus.

Contamination of fluidized bed-produced polycrystalline granules by phosphorus is reduced by employing as seals and/or packings, graphite containing <500 ppmw of phosphorus.

The present disclosure provides a reactor and a method for the production of high purity silicon granules. The reactor includes a reactor chamber; and the reaction chamber is equipped with a solid feeding port, auxiliary gas inlet, raw material gas inlet, and exhaust gas export. The reaction chamber is also equipped with an internal gas distributor; a preheating unit; and an external exhaust gas processing unit connected between the preheating unit and a gas inlet. The reaction chamber is further equipped with a surface finishing unit, a heating unit, and a dynamics-generating unit. The reaction occurs through decomposition of silicon-containing gas in a densely stacked, high purity granular silicon layer reaction bed in relative motion, and uses the exhaust gas for heating. The present invention achieves a large-scale, efficient, energy-saving, continuous, low-cost production of high purity silicon granules.

Prolonged operation campaigns in a fluidized bed reactor for producing granular polysilicon by deposition of silicon onto silicon seed particles from a silicon-containing precursor gas is made possible by employing a silicon-coated reaction tube which is not insulated above a region of the fluidized bed and as a result has a lower temperature such that the ratio of the thickness of the silicon on the reactor tube adjoining the fluidized bed to the coating thickness over the total reactor tube is from 7:1 to 1.5 to 1 after production campaign of from 15 to 500 days.

Prolonged operation campaigns in a fluidized bed reactor for producing granular polysilicon by deposition of silicon onto silicon seed particles from a silicon-containing precursor gas is made possible by employing a silicon-coated reaction tube which is not insulated above a region of the fluidized bed and as a result has a lower temperature such that the ratio of the thickness of the silicon on the reactor tube adjoining the fluidized bed to the coating thickness over the total reactor tube is from 7:1 to 1.5 to 1 after production campaign of from 15 to 500 days.