JP5430466B2 - Reactor for producing polycrystalline silicon and method for producing polycrystalline silicon using the same - Google Patents

Description

  The present invention relates to a method for producing polycrystalline silicon and a reactor for carrying out the method for producing polycrystalline silicon. More specifically, the present invention relates to a method for producing polycrystalline silicon for producing high-purity polycrystalline silicon for solar cells. The present invention relates to a manufacturing method and a reaction furnace for performing the manufacturing method of the polycrystalline silicon.

With the spread of solar cells in recent years, the demand for polycrystalline silicon is increasing rapidly. Conventionally, the Siemens method (Siemens Method) is mentioned as a method of manufacturing a high purity polycrystalline silicon. The Siemens method is a method of reducing trichlorosilane (SiHCl ₃ ) with hydrogen (H ₂ ). Polycrystalline silicon produced by the Siemens method has a very high purity of eleven-nine (11-N) and is used as silicon for semiconductors. Although the silicon for solar cells has also used a part of the product manufactured as this silicon for semiconductors, it does not require a purity as high as 11-N, and the Siemens method consumes a lot of power. There is a need for an inexpensive manufacturing method suitable for silicon.

Under such circumstances, a method for producing polycrystalline silicon by a zinc reduction method has been proposed as a method for producing silicon for solar cells, and the reaction thereof is represented by the following formula (1):
SiCl ₄ + 2Zn = Si + 2ZnCl ₂ (1)
It is shown by.

  In the method for producing polycrystalline silicon by the zinc reduction method, the purity of the produced polycrystalline silicon is about six-nine (6-N), which is lower than that of silicon for semiconductors, but compared with the Siemens method. It is a production method that is excellent in reaction efficiency and advantageous in production cost as much as about 5 times.

  As a method for producing polycrystalline silicon, for example, liquid or gaseous silicon tetrachloride is reduced with molten zinc in a reaction vessel, and a mixture containing the produced polycrystalline silicon and zinc chloride is taken out of the reaction vessel, A method for producing polycrystalline silicon (Patent Document 1), containing the mixture in a separation vessel, separating zinc chloride in the mixture, and then collecting polycrystalline silicon from the separation vessel; The liquid or gaseous silicon tetrachloride is reduced with molten zinc, and the mixture containing the produced polycrystalline silicon and zinc chloride is taken out of the reaction vessel, and the zinc chloride in the mixture is separated, A method for producing high-purity silicon that recovers crystalline silicon, wherein the separated zinc chloride is electrolyzed to recover metallic zinc and chlorine, and the recovered metallic zinc is again recovered from the silicon tetrachloride. A method for producing high-purity silicon, characterized in that it is used as a base agent and is used for chlorination of metallic silicon to produce silicon tetrachloride by synthesizing recovered chlorine with hydrogen to form hydrogen chloride (Patent Document) 2) has been reported.

  Patent Documents 1 and 2 both reduce liquid or gaseous silicon tetrachloride with molten zinc. However, in the method using molten zinc, there is a problem that the polycrystalline silicon becomes powdery, and the cost becomes high due to the complexity of post-processing, the difficulty of impurity treatment, and the difficulty of casting.

  Therefore, as a silicon production method for performing a zinc reduction method using silicon tetrachloride vapor and zinc vapor, for example, zinc provided on the side peripheral surface of the reaction tube while heating the reaction tube standing in the vertical direction. While supplying zinc vapor from the vapor supply port, silicon tetrachloride vapor is discharged from below the zinc vapor supply port upward along the central axis of the reaction tube, and the temperature distribution in the reaction tube is changed to the side peripheral surface. There has been reported a method for producing silicon powder such that the center axis side is lower than the side (Patent Document 3).

  There is also a silicon production apparatus that has a silicon compound supply pipe and a zinc supply pipe in a reaction vessel and discharges a reaction product gas containing silicon to the outside of the reaction vessel through a rectifying member in the reaction vessel (Patent Document 4). ).

  Patent Documents 3 and 4 both discharge reaction product gas containing silicon to the outside of the reaction vessel, and the obtained silicon is silicon powder. However, in addition to the problem that powdered silicon is very difficult to melt when it is melted for ingot production, there is a problem that the purity is low and the utility value is poor because the surface area per unit weight is large.

  For this reason, the shape of the obtained silicon is preferably a needle shape or flake shape having a certain size. As a method for producing acicular or flaky silicon, for example, high purity silicon tetrachloride and high purity zinc are vaporized and reacted in a gasified atmosphere, so that most of the silicon taken out as a product is acicular. Or the manufacturing method of the high purity silicon | silicone for solar cells which is flake shape is reported (patent document 5).

  In Patent Document 5, a reactor has a tantalum core or a silicon core that can be energized, and by raising the temperature of the core rod above the reaction temperature, needle-like and flaky silicon is placed on the core rod rather than the reactor. To be deposited.

Japanese Patent Laid-Open No. 11-011925 (Claims) JP-A-11-092130 (Claims) JP 2009-107896 A (Claims) JP 2009-167022 A (Claims) JP 2004-018370 A (Claims)

  In the zinc reduction method as in Patent Document 5, in order to extract silicon generated in the reaction furnace out of the reaction furnace, the reaction furnace is formed into a vertical cylindrical shape, and a lid that can be opened and closed is attached to an end portion thereof. There is a need. In the zinc reduction method, the inside of the reaction furnace and the outside air must be shut off, and the seal portion between the reaction furnace and the lid must be sufficiently sealed.

  In such a vertical reactor, various members are attached to the lid that is installed above the end of the vertical cylindrical side wall, and each time the batch reaction is repeated, Detachment is repeated. Quartz is often used in the reaction furnace of the zinc reduction method, but the material made of quartz has a drawback that it is easily damaged when a member is attached or detached. Further, the lower lid must be made of a material that is difficult to break due to the load when an insertion vessel or the like is installed in the reaction furnace. Therefore, it is preferable to use a material such as SUS for the lid.

  However, since the heating part of the reactor, that is, the side wall becomes a high temperature of about 1,000 ° C., when using a metal material as the side wall, extremely expensive heat-resistant steel must be used, and heat resistance such as alumina is used. When a conductive oxide material is used, a large-sized material is difficult to manufacture due to the problem of moldability, so a high heat-resistant material such as quartz is used from the viewpoint of cost and moldability. At this time, if only the side wall, which is the heating part, is made of quartz, and the lid is made of a material having a coefficient of thermal expansion that is significantly different from that of stainless steel such as SUS, quartz, etc. There was a problem that quartz was damaged.

  Further, in the zinc reduction method, the temperature of the reactor becomes as high as about 1,000 ° C. Therefore, the sealing material installed in the seal portion must be a material that can withstand a high temperature of about 1,000 ° C. As the sealing material having heat resistance at such a high temperature, only sealing materials such as spiral gaskets, metal jackets, metal gaskets and the like can be used. On the other hand, non-metallic soft gaskets such as rubber gaskets, resin gaskets, joint sheet gaskets, and expanded graphite gaskets have high sealing performance but low heat resistance. It cannot be used in places where the temperature is as high as about 000 ° C.

  However, it is necessary to tighten tightly in order to have sufficient airtightness with the metal gasket. In quartz reactors often used in the zinc reduction method, if the tightening force is strong, the reactor seal may be damaged, or the tightening portion may become brittle, reducing the durability of the reactor. In some cases, when the internal pressure is high, the required tightening force is too high, and the reaction force may be damaged by the tightening force.

  Therefore, an object of the present invention is a reactor for producing polycrystalline silicon by a zinc reduction method, and even if different materials are used for the side wall and the lid of the reactor, they are different due to the difference in thermal expansion during heating. It is to provide a reactor that is not damaged. Another object of the present invention is to provide a reaction furnace for producing polycrystalline silicon by a zinc reduction method, which has a sealing structure having a high sealing property between a side wall and a lid of the reaction furnace. .

  As a result of intensive studies to solve the problems in the conventional technology, the present inventors have provided a non-installation portion of the heater on the side wall of the reaction furnace, and the heater installation space and non-installation space in the reaction furnace Even if the inside of the reaction furnace is heated to about 1,000 ° C. during the reaction, (1) the side wall is insulated by a heat insulating material and the inert gas is supplied to the non-installation space of the heater in the reaction furnace. Since the temperature of the end portion and the lid can be lowered, even if the side wall and the lid are made of different materials, it is possible to suppress the difference in thermal expansion so that they are not destroyed, and (2) heat resistance is Although the sealing performance is low but the sealing performance such as resin that can absorb the difference in thermal expansion between the side wall and the lid can be applied, the temperature of the end portion of the side wall and the lid can be lowered. In order to complete the present invention Was Tsu.

  That is, the present invention (1) is a reaction furnace in which silicon tetrachloride and zinc are reacted to produce polycrystalline silicon, which is cylindrical and has a side wall of the reaction furnace having a flange at the end, A lid for closing the end, a seal member sandwiched between the flange of the side wall and the lid, a heater for heating the side wall, a heat insulating material installed near the end in the side wall, and the lid An inert gas supply pipe attached to the side wall, a heater non-installation portion is provided near the end of the side wall, and the heat insulating material is installed closer to the end than the heater installation portion. The present invention provides a reaction furnace for producing polycrystalline silicon.

Further, the invention (2), the using the reaction furnace for producing polycrystalline silicon of the present invention (1), silicon tetrachloride vapor and zinc vapor was supplied from the top of the reactor, the bottom of the reactor The exhaust gas is discharged from the reactor, the silicon tetrachloride vapor reacts with the zinc vapor in the reactor, the polycrystalline silicon is deposited in the reactor, and the silicon tetrachloride vapor reacts with the zinc vapor. In the meantime, the present invention provides a method for producing polycrystalline silicon, wherein an inert gas is supplied to a non-installation space of a heater in a reaction furnace.

  According to the present invention, a reactor for producing polycrystalline silicon by a zinc reduction method is used, and even if different materials are used for the side wall and the lid of the reactor, they are damaged due to a difference in thermal expansion during heating. It is possible to provide a reaction furnace that does not have any. Further, according to the present invention, it is possible to provide a reaction furnace for producing polycrystalline silicon by a zinc reduction method, which has a sealing structure with high sealing performance between a side wall and a lid of the reaction furnace. .

It is a typical end view of the example of the form of the reaction furnace for the polycrystalline silicon manufacture of this invention. It is the figure which expanded the edge part upper part vicinity of the side wall in FIG. It is a figure which shows the heat insulating material in FIG. It is a schematic diagram which shows the example of the installation position and shape of a supply pipe of silicon tetrachloride vapor and a supply pipe of zinc vapor. It is a schematic diagram which shows the example of the installation position and shape of a supply pipe of silicon tetrachloride vapor and a supply pipe of zinc vapor. FIG. 2 is an end view when a side wall and a silicon carbide rod in FIG. 1 are cut in a horizontal direction. It is a typical end view which shows the example of the form by which the insertion container is installed in the reaction furnace among the reaction furnaces for polycrystalline silicon manufacture of this invention. It is a typical end view which shows the example of the form by which the insertion container is installed in the reaction furnace among the reaction furnaces for polycrystalline silicon manufacture of this invention. It is a schematic diagram which shows the polycrystalline silicon obtained by the manufacturing method of the polycrystalline silicon of this invention.

  A method for producing polycrystalline silicon according to the present invention and a reactor for producing polycrystalline silicon according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic end view of an embodiment of a reactor for producing polycrystalline silicon according to the present invention. 2 is an enlarged view of the vicinity of the upper end of the side wall in FIG. FIG. 3 is a diagram showing the quartz plate in FIG. FIGS. 4 and 5 are schematic views showing examples of the installation positions and shapes of the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe, and (4-1) and FIG. 5 in FIG. It is a figure when the supply pipe | tube of a silicon vapor | steam and the supply pipe | tube of a zinc vapor | steam are seen from an upper side, (4-2) of FIG. 4 is an end elevation when cut in the perpendicular direction. 3 and 4, only the reactor, the silicon tetrachloride vapor supply pipe, and the zinc vapor supply pipe are shown.

  In FIG. 1, the reaction furnace 20 includes a side wall 1 having a vertically long cylindrical shape, a lid 2 (2a, 2b) for closing the upper and lower sides of the side wall 1, and a heater 5 for heating the reaction furnace 20. . A supply pipe 7 for silicon tetrachloride vapor 9 and a supply pipe 8 for zinc vapor 10 are attached to the upper part of the reaction furnace 20, and a discharge for discharging the exhaust gas 11 is provided at the lower part of the reaction furnace 20. A tube 6 is attached. In addition, a silicon carbide rod 3 is installed in the reaction furnace 20 via a silicon carbide rod fixing member 4. Specifically, the silicon carbide rod fixing member 4 is hooked on the furnace inner wall collar portion 12 formed on the inner wall of the side wall portion 1, so that the silicon carbide rod 3 is placed inside the reaction furnace 20. It is installed to protrude downward.

  One end of the supply pipe 7 for the silicon tetrachloride vapor is located inside the reaction furnace 20, and the other end is connected to a silicon tetrachloride evaporator. One end of the zinc vapor supply pipe 8 is located inside the reaction furnace 20, and the other end is connected to a zinc evaporator. Further, the exhaust pipe 6 serves as a recovery device for recovering the exhaust gas 11, that is, the zinc chloride gas generated when silicon tetrachloride and zinc react and the silicon tetrachloride vapor and zinc vapor which are unreacted gases. It is connected.

  As shown in FIG. 2, a seal member 18 is sandwiched between the flange portion 22 of the side wall 1 and the lid 2a, and the flange portion 22 of the side wall 1 and the lid 2a are By tightening with the nut 212, the space between the end 23 of the side wall 1 and the lid 2a is sealed. In FIG. 1, the sealing member 18, the bolt 211, and the nut 212 are not shown.

  In the reaction furnace 20, the side wall 1 protrudes above the end portion 13 a of the heater 5. The portion surrounded by the heater 5, that is, the heater side from the end portion 13a of the heater 5 (in FIG. 1, below the end portion 13a of the heater 5) is the installation portion 19 of the heater 5, The portion not surrounded by the heater 5, that is, the end portion side of the side wall 1 from the end portion 13a of the heater 5 (in FIG. 1, above the end portion 13a of the heater 5) is not installed. Part 24. Thus, in the reaction furnace 20, the non-installed portion 24 of the heater 5 is provided in the vicinity of the end portion 23 of the side wall 1.

  A quartz plate 17 is installed in the reaction furnace 20 in the vicinity of the end 23 of the side wall 1. The installation position of the quartz plate 17 is closer to the end of the side wall 1 than the installation part 19 of the heater 5.

  As shown in FIG. 3, the quartz plate 17 is a circular quartz plate member having legs 171. When a plurality of the quartz plates 17 are stacked, a gap 172 is formed between the plate-like portions 173. The quartz plate 17 functions as a heat insulating material by stacking a plurality of the quartz plates 17. In addition, when the silicon carbide rod fixing member 4 is made of a heat-insulating material such as opaque quartz (quartz having bubbles inside), sintered quartz (porous quartz), etc., the silicon carbide rod fixing member 4 also functions as a heat insulating material.

  In the reaction furnace 20, there is a heater non-installation space 241 in the reaction furnace. The lid 2a is provided with a nitrogen gas supply pipe 151 for supplying the nitrogen gas 16 to the heater non-installation space 241 in the reaction furnace. The space in the reactor surrounded by the side wall 1 of the heater non-installation portion is called a heater non-installation space 241 in the reaction furnace, and is surrounded by the side wall 1 of the heater installation portion. The space in the reaction furnace is called a heater installation space 191 in the reaction furnace.

  In the reaction furnace 20, a partition member 41 is installed in the vicinity of the lower end of the side wall 1 instead of the fixing member 4 of the silicon carbide rod, and the quartz plate 17 and the partition member 41 are supported by a support member. Except being supported by 111, it has the same structure as the vicinity of the upper end of the side wall 1. The partition member 41 receives the polycrystalline silicon that has not been deposited on the silicon carbide rod 3 (precipitation rod) and the polycrystalline silicon that has dropped from the silicon carbide rod 3 (precipitation rod) at the bottom of the reactor. There is a role.

  That is, in the vicinity of the lower end portion of the side wall 1, a sealing member (not shown) is sandwiched between the collar portion 22 of the side wall 1 and the lid 2b, and the collar portion 22 of the side wall 1 and the lid 2b is tightened with a bolt and a nut (not shown), so that the end portion of the side wall 1 and the lid 2b are sealed.

  The side wall 1 protrudes below the end portion 13 b of the heater 5. The portion surrounded by the heater 5, that is, the heater side from the end portion 13b of the heater 5 (in FIG. 1, above the end portion 5b of the heater 5) is an installation portion of the heater 5, and the heater 5, that is, the end portion side of the side wall 1 from the end portion 13 b of the heater 5 (below the end portion 5 b of the heater 5 in FIG. 1) is a non-installed portion of the heater 5. It is. Thus, the non-installed portion of the heater 5 is provided in the vicinity of the end portion of the side wall 1.

  A quartz plate 17 is installed in the vicinity of the end portion in the side wall 1. The installation position of the quartz plate 17 is closer to the end of the side wall 1 than the installation part of the heater 5.

  Similarly to the upper side of the lower side of the side wall 1, the quartz plate 17 is a circular quartz plate member having legs 171. The quartz plate 17 functions as a heat insulating material by stacking a plurality of the quartz plates 17. In addition, when the partition member 41 is made of a heat-insulating material such as opaque quartz (quartz having bubbles inside) or sintered quartz (porous quartz), the partition member 41 also functions as a heat insulating material. To do.

  In the reaction furnace 20, there is a heater non-installation space 241 in the reaction furnace. The lid 2b is provided with a nitrogen gas supply pipe 151 for supplying the nitrogen gas 16 to the heater non-installation space 241 in the reaction furnace.

  A method for producing polycrystalline silicon using the reactor 20 will be described. First, silicon tetrachloride and zinc are vaporized by respective evaporators, and silicon tetrachloride vapor 9 is heated from the silicon tetrachloride vapor supply pipe 7 and zinc vapor 10 is heated from the zinc vapor supply pipe 8 by the heater 5. The exhaust gas 11 is discharged from the discharge pipe 6 to the outside of the reaction furnace 20 while being supplied into the reaction furnace 20. At this time, silicon tetrachloride reacts with zinc in the reaction furnace 20 to produce polycrystalline silicon. However, since the silicon carbide rod 3 is installed in the reaction furnace 20, it is produced. Polycrystalline silicon is deposited on the silicon carbide rod 3. Since silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the reaction furnace 20 and the exhaust gas 11 is discharged from the lower part of the reaction furnace 20, the silicon tetrachloride vapor and the zinc vapor are Since the silicon carbide rod 3 is moving downward from the top of 20 and along the flow, a polycrystalline silicon crystal grows so as to cover the silicon carbide rod 3. Further, zinc chloride is also generated by the reaction of silicon tetrachloride and zinc, but the zinc chloride gas is discharged out of the exhaust pipe 6 as an exhaust gas 11 together with unreacted silicon tetrachloride vapor and zinc vapor. . During the reaction between silicon tetrachloride and zinc, nitrogen gas 16 is supplied from the nitrogen gas supply pipe 151. The nitrogen gas 16 supplied from the nitrogen gas supply pipe 151 to the heater non-installation space 241 in the reactor passes through the gap between the side wall 1 and the silicon carbide rod fixing member 4 or the partition member 41. Then, it enters the reaction furnace and is discharged out of the reaction furnace from the discharge pipe 6 together with the exhaust gas 11.

  Thus, silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the reaction furnace, exhaust gas is discharged from the lower part of the reaction furnace, and silicon tetrachloride vapor and zinc vapor react in the reaction furnace. However, by depositing the generated polycrystalline silicon on a silicon carbide rod, polycrystalline silicon can be produced by reacting silicon tetrachloride with zinc using the reactor 20.

  That is, the reactor for producing polycrystalline silicon according to the present invention is a reactor for reacting silicon tetrachloride and zinc to produce polycrystalline silicon, and is a cylindrical reactor having a flange at the end. A side wall, a lid that closes the end of the side wall, a seal member that is sandwiched between the flange of the side wall and the lid, a heater that heats the side wall, and an end near the end in the side wall A heat insulating material and an inert gas supply pipe attached to the lid; a heater non-installation portion is provided near the end of the side wall; A reaction furnace for producing polycrystalline silicon, characterized in that it is installed on the side of the section.

  The reaction furnace for producing polycrystalline silicon according to the first embodiment of the present invention is configured to use a material different from that of the side wall 1 as the material of the lid 2. The reactor for producing polycrystalline silicon according to the second embodiment of the present invention is a form in which a non-metallic gasket that is not a metallic gasket is used as the sealing member 18.

  The reactor for producing polycrystalline silicon according to the present invention has a vertically long shape comprising the side wall having a cylindrical shape and having a flange at the end, and a lid for closing the end of the side wall. That is, the shape of the reactor is a vertically long shape in which silicon tetrachloride vapor and zinc vapor supplied into the reactor from the upper part of the reactor react while moving downward from the upper part of the reactor to the lower part. Shape. In other words, the shape of the reaction furnace is such that the raw material vapor and the exhaust gas flow from the upper part to the lower part of the reaction furnace.

  Since the temperature in the reactor is about 1,000 ° C., the side wall of the reactor may be transparent quartz, opaque quartz, silicon carbide, silicon nitride, etc. Silicon carbide and silicon nitride are preferable because they are easy to handle when removed, and quartz is preferable from the viewpoint of cost.

  Examples of the material of the reactor lid relating to the reactor for producing polycrystalline silicon according to the first embodiment of the present invention include stainless steels such as martensite, ferrite, austenite, precipitation hardening, etc., iron, carbon steel Etc. In the reactor for producing polycrystalline silicon according to the present invention, since the temperature of the end portion of the side wall and the temperature of the lid is low, a material such as stainless steel, iron, or carbon steel is used for the lid, and the quartz material is used for the side wall. However, there is no difference in thermal expansion between the lid and the side wall so as to damage the side wall.

  The material of the reactor lid according to the reactor for producing polycrystalline silicon according to the second aspect of the present invention is transparent quartz, opaque quartz, silicon carbide, silicon nitride, martensite, ferrite, austenite, Examples include precipitation hardening type stainless steel, iron, carbon steel, and the like.

  In the reactor for producing polycrystalline silicon according to the first aspect of the present invention, the side wall and the lid are made of different materials. The combinations of the material of the side wall and the material of the lid are shown in Table 1, for example. Combinations are listed.

  In the reactor for producing polycrystalline silicon according to the second aspect of the present invention, the side wall and the lid may be the same material or different materials, and a combination of the side wall material and the lid material. Examples of the combinations include the combinations shown in Table 2.

  The size of the reactor is not particularly limited, but is appropriately selected depending on the supply conditions of silicon tetrachloride vapor and zinc vapor. In general, preferably, the length of the reactor in the vertical direction is 1,000 to 6,000 mm, and in the case of a cylindrical shape, the diameter is 200 to 2,000 mm.

The sealing member is a member for sealing between the end portion of the side wall and the lid by being sandwiched between the flange portion provided at the end portion of the side wall and the lid portion, The sealing member is not particularly limited as long as it exhibits sealing performance by tightening with a tightening force defined in the following JIS B8265, and gas does not leak between the end of the side wall and the lid. .
<JIS B8265>
The tightening force is calculated based on the following formula.
Wm1 = (π / 4) GGP + 2πbGmP = (πGP / 4) × (G + 8bm)
Wm2 = πbGy
Wm3 = σ3Ag
The tightening force (Wm) necessary for the seal is the maximum value among the above Wm1, Wm2 and Wm3.
P = Internal pressure G = Gas effective diameter b = Gasket effective width m = Gasket coefficient y = Minimum design tightening pressure σ3 = Minimum tightening surface pressure Ag = Gasket contact area (projected area)

  The seal member according to the reactor for producing polycrystalline silicon according to the second aspect of the present invention is a non-metallic soft gasket, and examples thereof include a rubber gasket, a resin gasket, a joint sheet gasket, and an expanded graphite gasket. Of these, rubber gaskets and resin gaskets are preferred. As the material of the rubber gasket, fluorinated rubber such as Viton (registered trademark) (heat resistant temperature of about 200 ° C), Kalrez (registered trademark) (heat resistant temperature of about 200 ° C), Perflo (registered trademark) (heat resistant temperature of 260 ° C), etc. Material, silicone rubber (heat resistant temperature around 200 ° C), fluorosilicone rubber (heat resistant temperature around 200 ° C), acrylic rubber (heat resistant temperature around 160 ° C), butyl rubber (heat resistant temperature around 140 ° C), ethylene propylene rubber (heat resistant temperature 140 ° C) Grade), nitrile rubber (heat resistant temperature around 120 ° C.), chloroprene rubber (heat resistant temperature around 110 ° C.), etc., and the resin gasket material is polytetrafluoroethylene (heat resistant temperature around 260 ° C.) , Polytetrafluoroethylene with graphite and / or inorganic filler added (heat-resistant temperature around 200 ° C Resin materials such as woven fabric such as asbestos cloth, glass cloth, and ceramic cloth (heat resistant temperature of about 150 ° C.) can be mentioned. The material of the joint sheet gasket is rubber, asbestos, polyamide fiber , Glass fiber, expanded graphite and the like (heat resistant temperature of about 200 ° C.), and the like. Examples of the material of the expanded graphite gasket include expanded graphite (heat resistant temperature of about 400 ° C.). In the reactor for producing polycrystalline silicon according to the present invention, the temperature of the vicinity of the end of the side wall and the lid is low, so that the sealing member is a non-metallic soft gasket excellent in hermeticity, for example, the rubber gasket, The resin gasket, the joint sheet gasket, and the expanded graphite gasket can be used.

  The seal member used in the reaction furnace for producing polycrystalline silicon according to the second embodiment of the present invention can be prevented from leaking by being tightened with a tightening pressure defined in JIS B8265. In the case of the sealing member used in the reactor for producing polycrystalline silicon according to the second embodiment of the present invention, the tightening pressure (surface pressure) defined in JIS B8265 is about 1 to 50 MPa, preferably The pressure is about 1 to 30 MPa, and sufficient sealing performance is exhibited even when the tightening pressure is low as compared with the metal gasket. Therefore, the sealing member according to the reaction furnace for producing polycrystalline silicon according to the second embodiment of the present invention is different from a metal gasket.

  The sealing member according to the reaction furnace for producing polycrystalline silicon according to the first aspect of the present invention is not particularly limited, and even a metal gasket is a reaction for producing polycrystalline silicon according to the second aspect of the present invention. The non-metallic soft gasket such as the rubber seal, the resin gasket, the joint sheet gasket, and the expanded graphite gasket may be used. Among these, the sealing member according to the reaction furnace for producing polycrystalline silicon according to the first aspect of the present invention is used for producing polycrystalline silicon according to the second aspect of the present invention in that the sealing performance is enhanced. The non-metallic soft gasket such as the seal member for the reaction furnace, that is, the rubber gasket, the resin gasket, the joint sheet gasket, and the expanded graphite gasket is preferable.

  A heater is installed around the side wall of the reactor. The heater is preferably an electric heater.

  The heat insulating material is not particularly limited as long as it can insulate the heat of the installation space of the heater in the reactor, such as opaque quartz, sintered quartz, cotton, refractory heat insulating brick, calcium silicate, The material itself has a heat insulating performance, for example, a quartz plate 17 shown in FIG. 1, or a material that exhibits a heat insulating performance by forming a gap between the plate-like portions by overlapping, or a heat exchanger Examples are those that lower the temperature. The heat insulating material may be a combination of a plurality of heat insulating materials.

  In addition, if the silicon carbide rod fixing member 4 and the partition member 41 in FIG. 1 also have heat insulation performance, that is, if they are formed of a material having heat insulation performance, included.

  The heat insulating material is installed in the vicinity of the end of the side wall in the reaction furnace, and is installed closer to the end of the side wall than the installation part of the heater. In other words, the heat insulating material is installed closer to the end of the side wall than the end of the heater. Therefore, the heat insulating material is installed in a non-installation space of the heater in the reaction furnace. In addition, it is preferable that the heat insulating material is entirely installed on the side of the side of the side wall from the heater installation portion, but a part of the heat insulating material exists in the non-installation space of the heater in the reactor. As long as the heat insulation performance is exhibited, a part of the heater may exist in the installation space of the heater in the reaction furnace. Further, the heat insulating material may be installed at a position in contact with the lid.

  In the reactor for producing polycrystalline silicon according to the present invention, the non-installed portion of the heater is provided in the vicinity of the end of the side wall. The range includes the size of the reactor, the temperature of the reactor, the heat insulation. It is appropriately selected depending on the material and shape of the material, the range where the heat insulating material is installed, and the like.

  In the reaction furnace for producing polycrystalline silicon according to the present invention, the inert gas supply pipe for supplying the inert gas to the non-installation space of the heater in the reaction furnace is installed. Then, by supplying the inert gas to the non-installation space of the heater in the reaction furnace through the inert gas supply pipe, the temperature of the non-installation space of the heater in the reaction furnace is set higher than that of the heater installation space. Can be reduced. The inert gas supplied to the non-installation space of the heater in the reactor enters the reactor through the gap between the side wall and the silicon carbide rod fixing member or the partition member, and serves as the exhaust gas. It is discharged out of the reactor.

  The reactor for producing polycrystalline silicon according to the present invention may have a cooling member for cooling the lid by water cooling or air cooling, if necessary.

  In the reactor for producing polycrystalline silicon according to the present invention, the supply pipe for the silicon tetrachloride vapor and the supply pipe for the zinc vapor are attached to the upper part of the reaction furnace. The discharge pipe is attached to the lower part of the reactor. In the reactor, a downward flow of the raw material vapor is formed in the reactor, and a position (vertical direction position) at which the reaction between silicon tetrachloride and zinc can be caused in the reactor. The silicon tetrachloride vapor supply pipe, the zinc vapor supply pipe, and the discharge pipe are attached.

  The shape and arrangement of the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe. For example, as shown in FIG. 4 (4-1), the silicon tetrachloride vapor supply pipe and the zinc vapor The horizontal portion of the supply pipe is arranged in a straight line, and as shown in (4-2), the tip of the supply pipe is L-shaped and the outlet of the supply pipe is directed downward. Moreover, as shown in FIG. 5, the example which prevents the horizontal part of the supply pipe | tube of this silicon tetrachloride vapor | steam and the supply pipe | tube of this zinc vapor | steam to line up on a straight line is mentioned. In the embodiment shown in FIG. 5, the silicon tetrachloride vapor and the zinc vapor move so as to swirl in the reactor.

  The reaction furnace for producing polycrystalline silicon according to the present invention may be provided with a deposition rod for depositing polycrystalline silicon in the side wall (inside the reaction furnace). Examples of the precipitation rod include a silicon carbide rod, a silicon nitride rod, a tantalum rod, and a silicon rod, and a silicon carbide rod is preferable. If the reactor of this embodiment is used, the produced polycrystalline silicon can be deposited on the deposition rod while reacting the silicon tetrachloride vapor and the zinc vapor.

  The deposition rod is installed in the reactor. The shape of the precipitation rod is preferably a prismatic shape or a cylindrical shape, and particularly preferably a cylindrical shape. In the case where the shape of the precipitation bar is a columnar shape, the diameter of the precipitation bar is preferably 1 to 20 cm, and particularly preferably 2 to 10 cm from the viewpoint of strength and processing surface. Further, the length of the precipitation bar existing between the lower side of the fixing member 4 of the precipitation bar and the upper side of the discharge pipe 6 is from the lower side of the fixation member 4 of the precipitation bar to the upper side of the discharge pipe 6. 20 to 120% is preferable, 40 to 100% is particularly preferable, and 50 to 90% is more preferable.

  Of the precipitation rods, the silicon carbide rod is a molded body of silicon carbide. Usually, the molded body of silicon carbide is a porous body having a large number of pores. The silicon carbide rod is a silicon-impregnated silicon carbide rod in which silicon is impregnated with porous silicon carbide, and the impregnated silicon becomes a seed of polycrystalline silicon crystals produced by the reaction, This is preferable in that the precipitation of polycrystalline silicon on the silicon carbide rod can be promoted. In the silicon-impregnated silicon carbide rod, the mass ratio of silicon carbide: impregnated silicon is preferably 80:20 to 95: 5, and particularly preferably 80:20 to 90:10. The silicon-impregnated silicon carbide rod is obtained by immersing a porous silicon carbide rod in molten silicon and impregnating the silicon carbide holes with the silicon.

  In addition, even if a porous silicon carbide rod not impregnated with silicon is installed in the reactor and a reaction between silicon tetrachloride vapor and zinc vapor is performed, carbonization is performed at an early stage of the reaction. In the porous structure near the outside of the silicon rod, contact between the silicon tetrachloride vapor and the zinc vapor occurs, and silicon is generated there, so the silicon carbide rod is impregnated in the vicinity of the outside of the silicon carbide rod. It becomes the same state as. Therefore, a porous silicon carbide rod not impregnated with silicon may be used. In particular, when the silicon carbide rod is used repeatedly, a porous silicon carbide rod not impregnated with silicon is used by repeated use. It becomes the state similar to the porous silicon carbide rod impregnated with.

  The number of the deposition rods may be one or two or more. Moreover, the installation position of this precipitation rod is not specifically limited. For example, when the number of the silicon carbide rods (the precipitation rods) is four, as shown in FIG. 6, the silicon carbide rods 3 are equidistant on an arc centered on the center of the side wall 1 (reactor). It is preferable that it is installed in. The number and position of the deposition rods are appropriately selected so that polycrystalline silicon is efficiently deposited according to the reaction conditions such as the supply conditions of the raw material vapor and the size of the reaction furnace. In addition, FIG. 6 is sectional drawing when the side wall and silicon carbide stick | rod in FIG. 1 are cut in the horizontal direction. In FIG. 6, only the side wall and the silicon carbide rod are shown for convenience of explanation.

  In FIG. 1, it is described that the silicon carbide rod 3 is installed in the reaction furnace 1. However, in the reaction furnace for producing polycrystalline silicon according to the present invention, the precipitation rod is placed in the reaction furnace. It may be installed or may not be installed.

  Among the reactors for producing polycrystalline silicon of the present invention, when using an embodiment in which the precipitation rod is not installed in the reactor, silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the reactor, By discharging exhaust gas from the lower part of the reactor and reacting silicon tetrachloride vapor with zinc vapor in the reactor, the polycrystalline silicon produced in the reactor is precipitated, thereby producing polycrystalline silicon. Can be manufactured.

  In the reaction furnace for producing polycrystalline silicon according to the present invention, an insertion vessel may be installed in the reaction furnace.

  Of the reaction furnace for producing polycrystalline silicon according to the present invention, an embodiment in which the insertion container is installed in the reaction furnace will be described with reference to FIGS. 7 and 8 are schematic end views showing an embodiment in which the inside of the insertion vessel is installed in the reaction furnace among the reaction furnaces for producing polycrystalline silicon according to the present invention.

  In FIG. 7, a reaction furnace 30a includes a side wall 1 having a vertically long cylindrical shape, a lid 2 (2a, 2b) for closing the upper and lower sides of the side wall 1, and a heater 5 for heating the reaction furnace 30a. . A supply pipe 7 for silicon tetrachloride vapor 9 and a supply pipe 8 for zinc vapor 10 are attached to the upper part of the reaction furnace 30a, and a discharge for discharging the exhaust gas 11 is provided at the lower part of the reaction furnace 30a. A tube 6 is attached. An insertion vessel 25 having a cylindrical side surface and a circular bottom surface is installed in the reaction furnace 30a. On the upper side of the insertion container 25, a lid member 251 of the insertion container is installed as a lid of the insertion container 25. A silicon carbide rod 3, a silicon tetrachloride vapor supply pipe 9, and a zinc vapor supply pipe 10 are fixed to the lid member 251 of the insertion container. The hydrocarbon rod 3 is installed so as to protrude downward into the insertion vessel 25. A discharge port 271 for discharging the exhaust gas 11 from the inside of the insertion container 25 is formed in the lower part of the insertion container 25, and the exhaust gas 11 passes through the discharge port 271 and is discharged into the discharge pipe 6. To the outside of the reaction furnace 30a.

  One end of the silicon tetrachloride vapor supply pipe 7 is located inside the reaction furnace 30a, and the other end is connected to a silicon tetrachloride evaporator. One end of the zinc vapor supply pipe 8 is located inside the reaction furnace 30a, and the other end is connected to a zinc evaporator. Further, the exhaust pipe 6 serves as a recovery device for recovering the exhaust gas 11, that is, the zinc chloride gas generated when silicon tetrachloride and zinc react and the silicon tetrachloride vapor and zinc vapor which are unreacted gases. It is connected.

  A sealing member (not shown) is sandwiched between the flange portion 22 of the side wall 1 and the lid 2a, and the flange portion 22 of the side wall and the lid 2a are tightened by bolts and nuts (not shown). The space between the end of the side wall 1 and the lid 2a is sealed.

  In the reaction furnace 30 a, the side wall 1 protrudes above the end portion 13 a of the heater 5. The portion surrounded by the heater 5, that is, the heater side from the end portion 13a of the heater 5 (in FIG. 7, below the end portion 13a of the heater 5) is an installation portion of the heater 5, The portion not surrounded by the heater 5, that is, the end portion side of the side wall 1 from the end portion 13a of the heater 5 (in FIG. 7, above the end portion 13a of the heater 5) is the non-installed portion of the heater 5. It is. Thus, in the reaction furnace 30a, the non-installed portion of the heater 5 is provided in the vicinity of the end portion of the side wall 1.

  Further, in the reaction furnace 30 a, a partition member 41 and a quartz plate 17 are installed in the vicinity of the end portion in the side wall 1. The installation position of the partition member 41 and the quartz plate 17 is closer to the end of the side wall 1 than the installation part of the heater 5.

  As shown in FIG. 3, the quartz plate 17 in FIG. 7 is a circular quartz plate material having legs 171 and functions as a heat insulating material by being stacked. In addition, when the partition member 41 is made of a heat-insulating material such as opaque quartz (quartz having bubbles inside) or sintered quartz (porous quartz), the partition member 41 also functions as a heat insulating material. To do.

  The reactor 30a has a heater non-installation space 241 in the reactor. The lid 2a is provided with a nitrogen gas supply pipe 151 for supplying the nitrogen gas 16 to the heater non-installation space 241 in the reaction furnace.

  In the reactor 30a, the support member 112 of the insertion container is installed near the lower end of the side wall, and the heat insulating material 17 and the partition member 41 are supported by the support member 111. , Having the same structure as the vicinity of the upper end of the side wall.

  In the embodiment shown in FIG. 7, the insertion container is installed in the reactor, and the lid member of the insertion container is also used as a fixing member for the silicon carbide rod, and is installed on the upper side of the insertion container. Thus, the silicon carbide rod is installed so as to protrude downward into the insertion container.

  The embodiment shown in FIG. 8 does not fix the silicon carbide rod 3 of the embodiment shown in FIG. 7 to the lid member of the insertion vessel that also serves as a fixing member for the silicon carbide rod, but instead of the bottom of the insertion vessel 25. It is the example of a form fixed to. In the embodiment shown in FIG. 8, the silicon carbide rod is installed so as to protrude upward into the insertion container.

  Among the reaction furnaces for producing polycrystalline silicon according to the present invention, an embodiment in which the insertion vessel is installed in the reaction furnace is to supply silicon tetrachloride vapor and zinc vapor into the insertion vessel, This is an embodiment in which polycrystalline silicon is deposited by reacting silicon tetrachloride vapor with zinc vapor in the insertion vessel.

  In the embodiment of the method for producing polycrystalline silicon according to the present invention, in the embodiment in which the insertion vessel is installed in the reaction vessel, the inert gas is circulated between the side wall of the reaction furnace and the gap between the insertion vessel. An active gas supply pipe (in FIG. 7 and FIG. 8, an inert gas supply pipe 153) is provided, and the inert gas is caused to flow through a gap between the side wall of the reactor and the insertion vessel. The exhaust gas, raw material vapor (silicon tetrachloride vapor, zinc vapor) to be supplied into the insertion vessel leaks into the gap between the side wall of the furnace and the insertion vessel, and the polycrystalline silicon is supplied to the reactor. Precipitation on the side wall can be prevented. The inert gas circulated in the gap between the side wall of the reaction furnace and the insertion container is discharged out of the reaction furnace from the discharge pipe together with the exhaust gas.

  The method for producing polycrystalline silicon according to the present invention uses the reaction furnace for producing polycrystalline silicon according to the present invention to supply silicon tetrachloride vapor and zinc vapor from the upper part of the reaction furnace and exhaust gas from the lower part of the reaction furnace. During the reaction of silicon tetrachloride vapor and zinc vapor, the reaction of silicon tetrachloride vapor and zinc vapor is performed in the reactor, and polycrystalline silicon is deposited in the reactor, while the reaction of silicon tetrachloride vapor and zinc vapor is performed. An active gas is supplied to a non-installation space of a heater in a reaction furnace.

  In the production of polycrystalline silicon by the zinc reduction method using silicon tetrachloride vapor and zinc vapor, when the silicon tetrachloride vapor and zinc vapor are vigorously stirred in the reaction furnace, fine polycrystalline particles having a diameter of 3 μm or less Silicon is produced, but such fine-grained polycrystalline silicon has a low packing density and takes time to melt. On the other hand, when silicon tetrachloride vapor and zinc vapor come into contact gently in the reactor, dendritic, needle-like or plate-like polycrystalline silicon is produced when contact is made preferably at a linear velocity of 5 cm / sec or less. However, such dendritic, needle-like or plate-like polycrystalline silicon is easier to melt and has a shorter melting time than fine-grained polycrystalline silicon. Therefore, when producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, conditions under which silicon tetrachloride vapor and zinc vapor are not vigorously stirred in the reactor, that is, the diameter is Silicon tetrachloride vapor and zinc vapor are supplied to the reactor under conditions where fine granular silicon of 3 μm or less is difficult to produce. That is, silicon tetrachloride vapor and zinc vapor are supplied to the reactor under the supply conditions of the raw material vapor in which dendritic, needle-like or plate-like polycrystalline silicon is easily generated. The supply condition of the raw material vapor that easily generates dendritic, needle-like or plate-like polycrystalline silicon is appropriately selected depending on the size of the reactor, the position or number of the silicon carbide rods installed, and the like.

  The supply ratio (molar ratio) of silicon tetrachloride vapor and zinc vapor is silicon tetrachloride vapor: zinc vapor = 0.9: 2-1.2: 2, preferably 0.95: 2-1.2. : 2 and particularly preferably 1: 2 to 1.1: 2. Further, the silicon tetrachloride vapor and the zinc vapor may be diluted with an inert gas such as nitrogen gas. In that case, the dilution rate of the silicon tetrachloride vapor is a volume ratio ((silicon tetrachloride vapor + inert gas). ) / Silicon tetrachloride vapor), preferably 1.01 to 1.5, particularly preferably 1.05 to 1.3, and the dilution rate of zinc vapor is a volume fraction ((zinc vapor + inert gas) / Zinc vapor), preferably 1.01 to 1.3, particularly preferably 1.03 to 1.2.

  According to “Chemical Handbook” (edited by the Chemical Society of Japan), the boiling point of zinc is 907 ° C. Therefore, the reactor is heated so that the temperature in the reactor becomes 907 ° C., which is the boiling point of zinc. . The temperature in the reactor is 907 to 1,200 ° C, preferably 930 to 1,100 ° C. Moreover, the pressure in the reactor is preferably 0 to 700 kPaG, particularly preferably 0 to 500 kPaG. By setting the reaction conditions within the above range, it is possible to stably deposit polycrystalline silicon on the silicon carbide rod.

  And in the manufacturing method of the polycrystalline silicon of this invention, during reaction of silicon tetrachloride vapor | steam and zinc vapor | steam, an inert gas is supplied to the non-installation space of the heater in a reaction furnace. The inert gas supplied to the heater non-installation space in the reaction furnace enters the reaction furnace through the gap between the side wall and the fixing member 4 or the partition member 41 of the silicon carbide rod, and the exhaust gas. At the same time, it is discharged out of the reactor from the discharge pipe.

  The supply amount of the inert gas to the non-installation space of the heater is appropriately selected depending on the size of the reaction furnace, the temperature in the reaction furnace, and the like.

  In the production of polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, the production of polycrystalline silicon is completed by stopping the supply of silicon tetrachloride vapor and zinc vapor. Thereafter, the reactor is cooled, and the deposited polycrystalline silicon is taken out from the reactor. For example, in the embodiment shown in FIG. 1, after the attached members such as the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 are removed, the lid 2 a on the upper side of the reaction furnace 20 is opened and the side wall is opened. The silicon carbide rod 3 fixed to the fixing member is taken out from the upper side of 1. Further, in the embodiment shown in FIGS. 7 and 8, after the attached members such as the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 are removed, the lid on the lower side of the reactors 30a and 30b is used. 2b is opened, and the insertion container 25 is taken out from the lower side of the side wall 1 together with the silicon carbide rod 3 fixed to the lid member of the insertion container.

  The precipitation rod and the insertion container used for the production of polycrystalline silicon are again used in the production of polycrystalline silicon. Further, before reuse, the precipitation rod and the insertion container may be washed with pure water or an acid such as hydrochloric acid, nitric acid or hydrofluoric acid.

Thus, since the polycrystalline silicon obtained using the reactor for producing polycrystalline silicon according to the present invention is produced using zinc as a reducing agent, it contains zinc. The zinc content in the polycrystalline silicon obtained by the method for producing polycrystalline silicon of the present invention is 0.1 to 100 ppm by mass, preferably 0.1 to 10 ppm by mass, particularly preferably 0.1 to 1 ppm by mass. It is. When the zinc content in the polycrystalline silicon is within the above range, a high-purity polycrystalline silicon ingot of 6-N or more can be produced. Note that the purity of the polycrystalline silicon is determined by high frequency induction plasma emission spectrometry (ICP-AES). The analysis method is as follows.
To 1.5 g of the obtained polycrystalline silicon, 16 ml of 38% hydrofluoric acid and 30 ml of 55% nitric acid are added and completely dissolved, and then evaporated to dryness. Next, the solution is fixed with 5 ml of 1% nitric acid, and the impurity concentration is measured by ICP-AES (IRIS Advantage / RP type manufactured by Thermo Fisher Scientific Co., Ltd.) to calculate the purity of the polycrystalline silicon.

  The main shape of the polycrystalline silicon obtained by the method for producing polycrystalline silicon of the present invention is a dendritic shape, a needle shape, or a plate shape, and is not a fine particle having a diameter of 3 μm or less. In the method for producing polycrystalline silicon according to the present invention, the silicon crystal grows in a dendritic or needle shape, so that it grows into a large dendritic or needle shape. In addition to the needle-like ones, there are also those that become plate-like, small dendrites or needle-like ones, and when scraping from the silicon carbide rod, the dendrites or needle-like ones are crushed and small dendrites Some of them are shaped like needles or needles. The size of the dendritic, needle-like or plate-like polycrystalline silicon is preferably 100 μm or more, particularly preferably 500 μm or more, and further preferably 1,000 μm or more. The dendritic, needle-like or plate-like polycrystalline silicon is preferably dendritic, needle-like or plate-like polycrystalline silicon in which 50% by mass or more does not pass through a screen of 100 μm mesh size. Particularly preferred is a dendritic, needle-like or plate-like polycrystalline silicon whose mass% or more does not pass through a screen of 500 μm mesh size. The dendritic shape is a shape comprising a trunk portion 31 and a branch portion 32 extending from the trunk portion 31 as shown in (9-1) of FIG. 9, and the needle shape is the shape of FIG. As shown in (9-2), it is a shape extending in a substantially straight line, and the plate shape is a shape extending in a substantially planar direction such as a scale shape or a flake shape. In addition, there is a shape in which the branches extend further from the dendritic branch 32 and the crystal extends. The size of the dendritic, needle-like or plate-like polycrystalline silicon is the length of the longest part of the crystal in the case of a dendritic shape (the length of 33a in (9-1) of FIG. 9). In the case of a needle shape, it indicates the length of the crystal (the length of 33b in (9-2) of FIG. 9), and in the case of a plate shape, it indicates the longest diameter of the crystal.

  The reaction furnace for producing polycrystalline silicon according to the present invention has a structure in which the end of the side wall and the lid are covered even when the inside of the reaction furnace is heated to about 1,000 ° C. in order to react silicon tetrachloride vapor and zinc vapor. Is not as high as 100 to 230 ° C, preferably 100 to 170 ° C.

  Therefore, according to the reactor for producing polycrystalline silicon according to the present invention, the side wall material and the lid have a large thermal expansion coefficient as in the case where the side wall material is quartz and the lid member is stainless steel. Even if different materials are used, the temperature at the time of reaction can be suppressed to a difference in thermal expansion amount so that they are not destroyed.

  Further, according to the reactor for producing polycrystalline silicon of the present invention, as a sealing member, the rubber gasket having low heat resistance but high sealing performance and capable of absorbing the difference in thermal expansion between the side wall and the lid Since the non-metallic soft gaskets such as the resin gasket, the joint sheet gasket, and the expanded graphite gasket can be used, a reactor having a structure with high sealing performance can be provided. Furthermore, since a soft gasket can be used as the seal member, the reaction furnace is not easily damaged, and the tightening pressure of the seal member for ensuring the sealing performance can be reduced. Is difficult to break, and therefore the durability of the reactor is increased.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

Example 1
1, the sealing member 18 is tightened with the following tightening force, air of 25 ° C. is supplied from the silicon tetrachloride vapor supply pipe 9, and the temperature in the reactor is 25 ° C. While the pressure was increased to 0.1 MPa, a leak test of air from the upper lid 2a was performed. The structure below the side wall was left as the reactor 20 in FIG.
As a result, no air leakage from the upper lid 2a was confirmed.
<Reactor>
Side wall: A quartz reaction tube having an inner diameter of 300 mm and a length of 2,500 mm is used. Lid: Quartz silicon carbide rod having a thickness of 20 mm: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon has a mass ratio of 85:15
Silicon carbide rod fixing member 4: Material is quartz, thickness is 15 mm
Quartz plate 17: 10 sheets, plate-like part thickness 5 mm, leg part length 10 mm
Length of the non-installation part 24 of the heater 5: 300 mm
Distance from the end of the heater to the lower end of the fixing member of the silicon carbide rod of the heater: 0 mm
Distance from the end 23 of the side wall to the upper end of the fixing member of the silicon carbide rod: 285 mm
<Seal material>
Viton (registered trademark: manufactured by DuPont Elastomer Co., Ltd., material is fluoro rubber) O-ring, P360 (call number defined in JIS B2401)
<Tightening force of sealing material>
Based on JIS B8265, the tightening force of the Viton (registered trademark) O-ring was calculated to be 10,630 N (Newton), and the gasket contact area was 607 mm ² , which was calculated from the tightening force and the gasket contact area. The tightening pressure (surface pressure) was 17.5 MPa (N / mm ² ).

(Example 2)
As a sealing material, instead of Viton (registered trademark) O-ring, PTFE gasket (manufactured by Japan Gore-Tex Co., Ltd., trade name Triguard gasket, outer diameter 378 mm, inner diameter 321 mm, thickness 3 mm) is used, and the sealing material This was performed in the same manner as in Example 1 except that the tightening force was set to the following value.
As a result, no air leakage from the upper lid 2a was confirmed.
<Tightening force of sealing material>
Based in JIS B8265, was calculated tightening force of the PTFE gasket is 104,449N, gasket contact area 5,222Mm ^2, and the clamping pressure calculated from the force and the gasket contact area fastening (surface pressure) is It was 20.0 MPa (N / mm ² ).

(Example 3)
Instead of a quartz lid, a SUS304 lid is used, and as a sealing material, instead of Viton (registered trademark), a metal gasket (Non-Asmetal Jacket Gasket N510, manufactured by Nippon Valqua Industries, Ltd., outer diameter 400 mm) , Inner diameter 360 mm, thickness 3.2 mm, coating material: soft aluminum), and the tightening force of the sealing material was set to the following values, and was performed in the same manner as in Example 1.
As a result, no air leakage from the upper lid 2a was confirmed. Further, after the leak test, the lid 2a was removed from the side wall 1 and the sealing surfaces of the side wall 1 and the lid 2a were confirmed. As a result, scratches due to gasket tightening were confirmed.
<Tightening force of sealing material>
When the tightening force of the metal gasket was calculated based on JIS B8265, it was 190,267N, the gasket contact area was 4,757 mm ² , and the tightening pressure (surface pressure) calculated from the tightening force and the gasket contact area was The pressure was 40.0 MPa (N / mm ² ).

Example 4
The reactor 20 shown in FIG. 1 is used, and the same Viton O-ring as in Example 1 is used as the seal member 18 with a clamping force of 10,630 N, and nitrogen gas at 1,000 ° C. is supplied with silicon tetrachloride vapor. It supplied from the pipe | tube, the inside of the reactor was heated to 930 degreeC, and it continued heating for 40 hours. It was 170 degreeC when the temperature inside the lid | cover 2a was measured. The structure below the side wall was left as the reactor 20 in FIG.
<Reactor>
Side wall: A quartz reaction tube having an inner diameter of 300 mm and a length of 2,500 mm is used. Lid: Quartz silicon carbide rod having a thickness of 20 mm: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon has a mass ratio of 85:15
Silicon carbide rod fixing member 4: Material is quartz, thickness is 15 mm
Quartz plate 17: 10 sheets, plate-like part thickness 5 mm, leg part length 10 mm
Length of the non-installation part 24 of the heater 5: 300 mm
Distance from the end of the heater to the lower end of the fixing member of the silicon carbide rod of the heater: 0 mm
Distance from the end 23 of the side wall to the upper end of the fixing member of the silicon carbide rod: 285 mm
Supply amount of nitrogen gas to the non-installation space 241 of the heater in the reactor: 10 L / min

  The difference in thermal expansion between the quartz side wall and the SUS lid at 170 ° C. is 1.2 mm or less in the nut seat pitch diameter (400 mm in this embodiment) of the bolt 211 attached to the flange portion 22 of the side wall. Therefore, even if the material of the lid of the reactor 20 of Example 4 is SUS and the reaction of silicon tetrachloride vapor and zinc vapor is performed at 930 ° C., the side wall made of quartz is destroyed due to the difference in thermal expansion. Never happen.

(Comparative Example 1)
The heater installation part of the reaction furnace 20 shown in FIG. 1 is changed as follows, and the quartz plate 17 is not installed and the nitrogen gas is not supplied from the nitrogen gas supply pipe 151. Nitrogen gas was supplied from a supply pipe for silicon tetrachloride vapor and a supply pipe for zinc vapor, the inside of the reactor was heated to 930 ° C., and heating was continued for 40 hours. It was 900 degreeC when the temperature inside the lid | cover 2a was measured. The structure below the side wall was left as the reactor 20 in FIG.
<Reactor>
Side wall: A quartz reaction tube having an inner diameter of 300 mm and a length of 2,500 mm is used. Lid: Quartz silicon carbide rod having a thickness of 20 mm: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon has a mass ratio of 85:15
Fixing member of silicon carbide rod: quartz material, thickness 15mm
Non-installed heater length: 200mm
Distance from the end of the heater to the upper end of the fixing member of the silicon carbide rod of the heater: 85 mm
Distance from the end 23 of the side wall to the upper end of the fixing member of the silicon carbide rod: 285 mm
In addition, since the length of the non-installation part of the heater was 200 mm, the fixing member of the silicon carbide rod was present in the installation space of the heater in the reaction furnace.

  Since the difference in thermal expansion between the quartz side wall and the SUS lid at 1,000 ° C. is large, in the reactor structure of Comparative Example 1, the side wall of the reactor is quartz and the lid material When the reaction of silicon tetrachloride vapor and zinc vapor is performed at 930 ° C., the quartz side wall is destroyed due to the difference in thermal expansion.

  According to the present invention, since the sealing of the reaction furnace can be performed using a rubber material or a resin material as a sealing material, and a metal material such as SUS can be used for the lid, the durability of the reaction furnace is improved. Therefore, polycrystalline silicon can be manufactured at a low cost.

DESCRIPTION OF SYMBOLS 1 Reactor side wall 2, 2a, 2b Lid 3 Silicon carbide rod 4 Silicon carbide rod fixing member 5 Heater 6 Discharge pipe 7 Silicon tetrachloride vapor supply pipe 8 Zinc vapor supply pipe 9 Silicon tetrachloride vapor 10 Zinc vapor 11 Exhaust gas 12, 121 Furnace wall collars 13a, 13b Heater end 16 Nitrogen gas 17 Quartz plate 18 Seal member 19 Heater installation part 20, 30a, 30b Reactor 22 Side wall collar 23 Side wall edge 24 Heater Non-installation portion 25 Insertion vessel 31 Trunk portion 32 Branch portion 41 Partition members 111 and 112 Support members 151 and 153 Nitrogen gas supply pipe 171 Leg portion 172 Air gap 173 Plate portion 191 Heater installation space 211 in reactor Reactor bolt 212 Nut 241 Heater non-installation space 251 in the reactor Furnace cover member 271 Insertion container outlet

Claims (5)

  A reaction furnace for reacting silicon tetrachloride and zinc to produce polycrystalline silicon, the reaction furnace having a cylindrical shape and having a flange at the end, a lid for closing the end of the side wall, and the side wall A seal member sandwiched between the flange portion of the lid and the lid, a heater for heating the side wall, a heat insulating material installed near an end in the side wall, and supply of an inert gas attached to the lid And a non-installed portion of the heater in the vicinity of the end of the side wall, and the heat insulating material is installed on the end side from the installed portion of the heater. Production reactor.   2. The reaction furnace for producing polycrystalline silicon according to claim 1, wherein a silicon carbide rod is installed in the reaction furnace.   The silicon carbide rod is a silicon-impregnated silicon carbide rod in which porous silicon carbide is impregnated with silicon, and a mass ratio of silicon carbide: impregnated silicon is 80:20 to 95: 5. Item 3. A reactor for producing polycrystalline silicon according to Item 2.   The reactor for producing polycrystalline silicon according to any one of claims 1 to 3, wherein an insertion vessel is installed in the reactor. Using the reactor of claims 1 to 4 for producing polycrystalline silicon according to any one of the silicon tetrachloride vapor and zinc vapor was supplied from the top of the reactor, discharging the exhaust gas from the bottom of the reactor Then, the reaction between the silicon tetrachloride vapor and the zinc vapor is performed in the reaction furnace, the polycrystalline silicon is deposited in the reaction furnace, and the reaction between the silicon tetrachloride vapor and the zinc vapor is performed. Is supplied to the non-installation space of the heater in the reaction furnace.