Provided is a polycrystalline silicon rod suitable as a raw material for production of single-crystalline silicon. A crystal piece (evaluation sample) is collected from a polycrystalline silicon rod grown by a Siemens method, and a polycrystalline silicon rod in which an area ratio of a crystal grain having a particle size of 100 nm or less is 3% or more is sorted out as the raw material for production of single-crystalline silicon. When single-crystalline silicon is grown by an FZ method using the polycrystalline silicon rod as a raw material, the occurrence of dislocation is remarkably suppressed.

Provided is a polycrystalline silicon rod suitable as a raw material for production of single-crystalline silicon. A crystal piece (evaluation sample) is collected from a polycrystalline silicon rod grown by a Siemens method, and a polycrystalline silicon rod in which an area ratio of a crystal grain having a particle size of 100 nm or less is 3% or more is sorted out as the raw material for production of single-crystalline silicon. When single-crystalline silicon is grown by an FZ method using the polycrystalline silicon rod as a raw material, the occurrence of dislocation is remarkably suppressed.

A reaction furnace for producing a polycrystalline silicon according to the present invention is designed so as to have an in-furnace reaction space in which a reaction space cross-sectional area ratio (S=[S.sub.0−S.sub.R]/S.sub.R) satisfies 2.5 or more, which is defined by an inner cross-sectional area (So) of a reaction furnace, which is perpendicular to a straight body portion of the reaction furnace, and a total sum (S.sub.R) of cross-sectional areas of polycrystalline silicon rods that are grown by precipitation of polycrystalline silicon, in a case where a diameter of the polycrystalline silicon rod is 140 mm or more. Such a reaction furnace has a sufficient in-furnace reaction space even when the diameter of the polycrystalline silicon rod has been expanded, and accordingly an appropriate circulation of a gas in the reaction furnace is kept.

A reaction furnace for producing a polycrystalline silicon according to the present invention is designed so as to have an in-furnace reaction space in which a reaction space cross-sectional area ratio (S=[S.sub.0−S.sub.R]/S.sub.R) satisfies 2.5 or more, which is defined by an inner cross-sectional area (So) of a reaction furnace, which is perpendicular to a straight body portion of the reaction furnace, and a total sum (S.sub.R) of cross-sectional areas of polycrystalline silicon rods that are grown by precipitation of polycrystalline silicon, in a case where a diameter of the polycrystalline silicon rod is 140 mm or more. Such a reaction furnace has a sufficient in-furnace reaction space even when the diameter of the polycrystalline silicon rod has been expanded, and accordingly an appropriate circulation of a gas in the reaction furnace is kept.

A method and system of igniting one or more filaments for silicon production includes applying an output voltage to the one or more filaments using a transformer connected with the one or more filaments. In addition, the method includes supplying, in combination with the application of the output voltage, a current to a primary winding of the transformer via a choke to limit the current to a first predetermined current threshold range. The combination of the supplied current and applied output voltage allows a predetermined output range to be generated from a power supply device initially required to ignite the one or more filaments.

A method and system of igniting one or more filaments for silicon production includes applying an output voltage to the one or more filaments using a transformer connected with the one or more filaments. In addition, the method includes supplying, in combination with the application of the output voltage, a current to a primary winding of the transformer via a choke to limit the current to a first predetermined current threshold range. The combination of the supplied current and applied output voltage allows a predetermined output range to be generated from a power supply device initially required to ignite the one or more filaments.

Polycrystalline silicon with low contamination by impurities, especially boron and phosphorus, is manufactured by the Siemens process or by the fluidized bed process, in which deposition of polycrystalline silicon takes place in a reactor maintained within a clean room of the 1 to 100,000 class, and air entering the facility enclosing the reactors is filtered by a multiple stage filtration system wherein coarse and fine filter elements contain less than 0.1% by weight of boron and phosphorus and less than 0.01% by weight of arsenic and aluminum. Following production of the polycrystalline silicon, the polycrystalline silicon may be further treated by steps such as comminution, classifying, wet-chemical treatment, and packing, all these further steps also preferably taking place within a clean room of the 1 to 100,000 class.

Polycrystalline silicon with low contamination by impurities, especially boron and phosphorus, is manufactured by the Siemens process or by the fluidized bed process, in which deposition of polycrystalline silicon takes place in a reactor maintained within a clean room of the 1 to 100,000 class, and air entering the facility enclosing the reactors is filtered by a multiple stage filtration system wherein coarse and fine filter elements contain less than 0.1% by weight of boron and phosphorus and less than 0.01% by weight of arsenic and aluminum. Following production of the polycrystalline silicon, the polycrystalline silicon may be further treated by steps such as comminution, classifying, wet-chemical treatment, and packing, all these further steps also preferably taking place within a clean room of the 1 to 100,000 class.

A method for producing polycrystalline silicon includes introducing a reaction gas, which in addition to hydrogen contains silane and/or at least one halosilane, into a reaction space of a gas phase deposition reactor. The reaction space includes at least one heated filament rod upon which by deposition silicon is deposited to form a polycrystalline silicon rod. During the deposition, the the morphology of the silicon rod is determined.

A method for producing polycrystalline silicon includes introducing a reaction gas, which in addition to hydrogen contains silane and/or at least one halosilane, into a reaction space of a gas phase deposition reactor. The reaction space includes at least one heated filament rod upon which by deposition silicon is deposited to form a polycrystalline silicon rod. During the deposition, the the morphology of the silicon rod is determined.