Shin-etsu Chemical Co., Ltd.

Shin-etsu Chemical C O., Ltd.

Yasushi Kurosawa

Shigeyoshi Netsu

Naruhiro Hoshino

Kyoji Oguro

Takaaki Shimizu

Fumitaka Kume

Tetsuro Okada

Shinichi Kurotani

A reactoraccording to the present invention includes a heater storage section serving as a space section capable of accommodating a carbon heater for initial heating of silicon core wires. A carbon heateris loaded in a deposition reaction spacein the reactoronly when necessary for initial heating of silicon core wires. After initial heating of the silicon core wiresis finished, the carbon heateris unloaded from the deposition reaction space to the heater storage section. As a result, the carbon heateris not unduly damaged in the reactor any longer and its deterioration is reduced. In addition, because of reduction in reaction with hydrogen gas in the reactor, the generation of methane is reduced, and thus carbon contamination of polycrystalline silicon is reduced.

Method for producing polycrystalline silicon

A reactoraccording to the present invention includes a heater storage section serving as a space section capable of accommodating a carbon heater to initial heating of silicon core wires. A carbon heateris loaded in a deposition reaction spacein the reactoronly when necessary for initial heating of silicon core wires. After initial heating of the silicon core wiresis finished, the carbon heateris unloaded from the deposition reaction space to the heater storage section. As a result, the carbon heateris not unduly damaged in the reactor any longer and its deterioration is reduced. In addition, because of reduction in reaction with hydrogen gas in the reactor, the generation of methane is reduced, and thus carbon contamination of polycrystalline silicon is reduced.

Reactor for polycrystalline silicon production and method for producing polycrystalline silicon

The present invention provides a technique by which heat can be efficiently recovered from a coolant used to cool a reactor, and contamination with dopant impurities from an inner wall of a reactor when polycrystalline silicon is deposited within the reactor can be reduced to produce high-purity polycrystalline silicon. With the use of hot waterhaving a temperature higher than a standard boiling point as a coolant fed to the reactor, the temperature of the reactor inner wall is kept at a temperature of not more than 370&#xb0; C. Additionally, the pressure of the hot waterto be recovered is reduced by a pressure control section provided in a coolant tankto generate steam. Thereby, a part of the hot water is taken out as steam to the outside, and reused as a heating source for another application.

System for producing polycrystalline silicon, apparatus for producing polycrystalline silicon, and process for producing polycrystalline silicon

In order to obtain a polycrystalline silicon rod having an excellent shape, the placement relation between a source gas supplying nozzleand metal electrodesthat are provided in a reactor is appropriately designed. The area of a disc-like base plateis S. An imaginary concentric circle C (radius c) centered at the center of the disc-like base platehas an area S=S/2. Further, a concentric circle A and a concentric circle B are imaginary concentric circles having the same center as that of the concentric circle C and having a radius a and a radius b, respectively (a&#x3c;b&#x3c;c). In the present invention, the electrode pairsare placed inside of the imaginary concentric circle C and outside of the imaginary concentric circle B, and the gas supplying nozzle 9 is placed inside of the imaginary concentric circle A.

Polycrystalline silicon manufacturing apparatus and polycrystalline silicon manufacturing method

Raw material gas supply nozzles are arranged within a virtual concentric circle having its center at the center of a disk-like base plate (having an area half as large as an area of the base plate). Raw material gas is ejected at a flow velocity of 150 m/sec or more into a bell jar from the gas supply nozzles. In addition to one gas supply nozzle provided in a center portion of the base plate, three gas supply nozzles can be arranged at the vertex positions of a regular triangle inscribed in a circumscribed circle having its center at the gas supply nozzle in the center portion. With the gas supply nozzles so arranged, a smooth circulating flow is formed within a reactor.

Apparatus for producing polycrystalline silicon and method for producing polycrystalline silicon

The present invention provides a method of producing polycrystalline silicon in which silicon is precipitated on a silicon core wire to obtain a polycrystalline silicon rod. In an initial stage (former step) of a precipitation reaction, a reaction rate is not increased by supplying a large amount of source gas to a reactor but the reaction rate is increased by increasing a concentration of the source gas to be supplied, and in a latter step after the former step, the probability of occurrence of popcorn is reduced using an effect of high-speed forced convection caused by blowing the source gas into the reactor at high speed. Thus, a high-purity polycrystalline silicon rod with little popcorn can be produced without reducing production efficiency even in a reaction system with high pressure, high load, and high speed.

Production method for polycrystalline silicon, and reactor for polycrystalline silicon production

In a method according to the present invention, an occurrence ratio of popcorn is suppressed by adjusting kinetic energy of a source gas supplied to a reaction furnace for producing polycrystalline silicon with a Siemens method (flow velocity and a supply amount of the source gas in source gas supply nozzle ejection ports). Specifically, in performing deposition reaction of the polycrystalline silicon under a reaction pressure of 0.25 MPa to 0.9 MPa, when flow velocity of the source gas in gas supply ports of the source gas supply nozzles () is represented as u (m/sec), a source gas supply amount is represented as Q (kg/sec), and an inner volume of the reaction furnace () is represented as V (m), values of u and Q of each of the source gas supply nozzles () are set such that a total &#x3a3;(Q&#xd7;u/V) of values Q&#xd7;u/V is equal to or larger than 2500 (kg/m&#xb7;sec).

Method for supplying source gas for producing polycrystalline silicon and polycrystalline silicon

An inner wallof a reactorhas a two-layer structure: an anticorrosive layercomprising an alloy material having high anticorrosiveness is provided on the inner side of the reactor contacting a corrosive process gas, and a heat conductive layerfor efficiently conducting the heat within the reactorfrom an inner wall surface to a coolant flow passageis provided on the outer side of the reactor (outer-wall side). The anticorrosive layercomprises an alloy material having a composition for which a value R, defined by R=[Cr]+[Ni]&#x2212;1.5 [Si], is not less than 40% wherein [Cr] is a mass content (% by mass) of chromium (Cr), [Ni] is a mass content (% by mass) of nickel (Ni), and [Si] is a mass content (% by mass) of silicon (Si).

Reactor for producing polycrystalline silicon, system for producing polycrystalline silicon, and process for producing polycrystalline silicon

A bell jar includes a metallic bell jar (), and a metallic base plate () on which the bell jar () is placed, and packing () seals an inside of a container. To the base plate (), a pressure gauge (), a gas introduction line (), and a gas discharge line () are connected so as to allow monitoring of internal pressure of the bell jar () and introduction and discharge of a gas. A vacuum pump () is provided in a path of the gas discharge line (), and the vacuum pump () reduces internal pressure of the bell jar so as to be lower than vapor pressure of water. The vacuum pump () reduces the internal pressure of the bell jar so as to be lower than vapor pressure of water, thereby efficiently removing moisture, and completing drying of the bell jar in a short time.

Method for cleaning bell jar, method for producing polycrystalline silicon, and apparatus for drying bell jar

The present invention provides a technique by which heat can be efficiently recovered from a coolant used to cool a reactor, and contamination with dopant impurities from an inner wall of a reactor when polycrystalline silicon is deposited within the reactor can be reduced to produce high-purity polycrystalline silicon. With the use of hot waterhaving a temperature higher than a standard boiling point as a coolant fed to the reactorthe temperature of the reactor inner wall is kept at a temperature of not more than 370&#xb0; C. Additionally, the pressure of the hot waterto be recovered is reduced by a pressure control section provided in a coolant tankto generate steam. Thereby, a part of the hot water is taken out as steam to the outside, and reused as a heating source for another application.

The reaction exhaust gas from which chlorosilanes and hydrogen chloride have been removed in a hydrogen chloride absorption unit () is introduced to an adsorption unit () to recover a purified hydrogen (S). Activated carbon is packed in the adsorption unit (), the gas, which is mainly composed of hydrogen, is passed through the activated carbon-packed layer during which unseparated chlorosilanes, hydrogen chloride, nitrogen, carbon monoxide, methane, and monosilane contained in the gas are adsorbed on the activated carbon and removed from the gas, and thereby the purified hydrogen is obtained. Nitrogen, carbon monoxide, methane and monosilane are a compressed gas in the state of adsorption, whereas hydrogen chloride and chlorosilanes are a liquid in the state of adsorption, and require a vaporization heat during desorption. Using these properties, the separation of hydrogen chloride and chlorosilanes from other impurity components is possible merely by separating the pathways for the desorbed gas.

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Niigata, Japan

Yasushi Kurosawa