Abstract: A cylindrical vessel made of carbon is used in the production of silicon. The inner surface of the vessel comes into contact with a silicon melt, wherein the permeation with silicon melt is reduced, formation of SiC is suppressed, and the vessel is resistant to deformation even when volumetric expansion ascribable to silicon is brought about. The carbon-made cylindrical vessel is made of a carbon material having a bulk specific gravity of 1.8 or more. The thermal expansion coefficient of the carbon material at 350 to 450° C. is preferably 3.5×10?6/° C. to 6.0×10?6/° C. A process for producing silicon uses said vessel wherein a chlorosilane is reacted with hydrogen.

Abstract: A polycrystalline silicon production apparatus is provided whereby when deposited silicon is caused to drip down into an underlying collection part by heating the reaction tube inner surface at a temperature equal to or above the melting point of silicon, the silicon melt can be prevented from solidifying at a lower end portion of the reaction tube due to temperature lowering at the lower end portion. When a reaction tube is heated with a high frequency heating coil, the temperature lowering at a lower end portion of the reaction tube is prevented through temperature lowering prevention means which may be an infrared device capable of heating the outer periphery of the lower end portion by means of infrared rays, or which may be a lower end coil that is constituted by a coil near the lower end of the high frequency heating coil and has an increased heating intensity relative to an upper coil.

Abstract: A solidified mass for a high-purity multicrystal silicon material that is preferably applicable to producing crystal type silicon ingots for photo voltaics, and a process for producing the solidified mass are provided. The mass of silicon solidified from molten state is a solidified mass produced by dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, said solidified mass containing bubbles and having (i) an apparent density of not less than 1.5 g/cm3 and not more than 2.2 g/cm3 and (ii) a compressive strength of not less than 5 MPa and not more than 50 MPa. The process for producing a mass of silicon solidified from molten state includes the steps of dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, wherein the surface temperature of the vessel for receiving the molten silicon is not lower than 0° C. and not higher than 1000° C.

Abstract: It is an object of the present invention to prevent leakage of a raw material gas or molten silicon in a carbon columnar container which is constructed by connecting plural carbon cylindrical members to each other by a screw portion provided along the periphery of an end of each of the cylindrical members, by sealing a gap present at the connection portion through a high-reliability method that causes no cracking or the like.

Abstract: It is an object to provide a silicon manufacturing apparatus that suppresses a silicon deposition to the bottom end portion of the reaction vessel and to a section other than the inside face of the reaction vessel except for the bottom end portion, thereby enabling a stable operation for a long time, for a silicon manufacturing apparatus that introduces a reaction gas to the inside wall of the heated reaction vessel to deposit silicon and that withdraws the deposited silicon from an opening at the bottom end portion of the reaction vessel. A first gas supply port 31 that is formed by a circular slit and that supplies a sealing gas and/or an etching gas to the bottom end portion is formed on the peripheral side around the bottom end portion of the reaction vessel.

Abstract: A solidified mass for a high-purity multicrystal silicon material that is preferably applicable to producing crystal type silicon ingots for photo voltaics, and a process for producing the solidified mass are provided. The mass of silicon solidified from molten state is a solidified mass produced by dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, said solidified mass containing bubbles and having (i) an apparent density of not less than 1.5 g/cm3 and not more than 2.2 g/cm3 and (ii) a compressive strength of not less than 5 MPa and not more than 50 MPa. The process for producing a mass of silicon solidified from molten state includes the steps of dropping molten silicon into a receiving vessel and allowing the vessel to receive the molten silicon, wherein the surface temperature of the vessel for receiving the molten silicon is not lower than 0° C. and not higher than 1000° C.

Abstract: A cylindrical vessel made of carbon is used in the production of silicon. The inner surface of the vessel comes into contact with a silicon melt, wherein the permeation with silicon melt is reduced, formation of SiC is suppressed, and the vessel is resistant to deformation even when volumetric expansion ascribable to silicon is brought about. The carbon-made cylindrical vessel is made of a carbon material having a bulk specific gravity of 1.8 or more. The thermal expansion coefficient of the carbon material at 350 to 450° C. is preferably 3.5×10?6/° C. to 6.0×10?6/° C. A process for producing silicon uses said vessel wherein a chlorosilane is reacted with hydrogen.

Abstract: A polycrystalline silicon production apparatus is provided whereby when deposited silicon is caused to drip down into an underlying collection part by heating the reaction tube inner surface at a temperature equal to or above the melting point of silicon, the silicon melt can be prevented from solidifying at a lower end portion of the reaction tube due to temperature lowering at the lower end portion. When a reaction tube is heated with a high frequency heating coil, the temperature lowering at a lower end portion of the reaction tube is prevented through temperature lowering prevention means which may be an infrared device capable of heating the outer periphery of the lower end portion by means of infrared rays, or which may be a lower end coil that is constituted by a coil near the lower end of the high frequency heating coil and has an increased heating intensity relative to an upper coil.