JP5383604B2 - Reactor for the production of polycrystalline silicon - Google Patents

Description

  The present invention relates to a reactor for producing polycrystalline silicon, and more particularly to a reactor used for producing high-purity polycrystalline silicon for solar cells.

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 polycrystalline silicon becomes powdery and is expensive 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)

  However, in Patent Document 5, although tantalum cores or silicon cores can be used to deposit silicon to be generated on these cores, silicon is also deposited on the furnace wall of the reactor.

  And in the production of polycrystalline silicon by the zinc reduction method that repeats the batch process, when silicon is deposited on the furnace wall of the reactor after the end of one batch, the silicon is removed from the furnace wall before performing the next batch process. Although it is necessary to remove it, it is difficult to separate the silicon deposited on the furnace wall, which means that the furnace wall is damaged or broken, and it takes time to remove silicon, which decreases the production efficiency. There was a problem.

  Further, since all of the raw material silicon tetrachloride gas and zinc gas do not react in the reactor, unreacted silicon tetrachloride gas and zinc gas are discharged from the exhaust gas discharge pipe.

  For this reason, in the conventional reactor of Patent Document 5 and the like, silicon is deposited even in the exhaust gas exhaust pipe, so that there is a problem that silicon blocks the exhaust pipe.

  Therefore, an object of the present invention is a reaction furnace for producing polycrystalline silicon by a zinc reduction method, which can prevent precipitation of polycrystalline silicon in a furnace wall and a discharge pipe of the reaction furnace. Is to provide.

  As a result of intensive research in order to solve the above-described problems in the prior art, the inventors have installed an insertion vessel in the reaction furnace, installed an intubation tube for the discharge tube in the discharge tube, and the interpolation By surrounding the exhaust gas discharge port formed in the lower part of the container, forming an exhaust gas leakage prevention wall, and allowing the exhaust gas leakage prevention wall to enter the tube of the exhaust pipe intubation tube, The present inventors have found that the above problems can be solved and have completed the present invention.

That is, the present invention is a reactor for reacting silicon tetrachloride and zinc to produce polycrystalline silicon,
An insertion vessel is installed in the reaction furnace, and an exhaust gas discharge port is formed in the lower part of the insertion vessel. An exhaust gas surrounding the discharge port is formed on the outer wall of the insertion vessel. Leakage prevention wall is formed,
A silicon tetrachloride vapor supply pipe for supplying silicon tetrachloride vapor into the insertion vessel and a zinc vapor supply tube for supplying zinc vapor into the insertion vessel are provided at the top of the reactor. And
At the bottom of the reactor, has a discharge pipe for discharging exhaust gas,
The reaction furnace has an inert gas supply pipe for supplying an inert gas in the reaction furnace,
In the discharge pipe, an intubation for the discharge pipe is installed,
The exhaust gas leakage prevention wall enters the inside of the exhaust pipe intubation, and between the exhaust pipe intubation and the exhaust gas leakage prevention wall, and the pipe end of the exhaust pipe intubation and the insertion A gap is formed between the container and
A reactor for producing polycrystalline silicon characterized by the above is provided.

  According to the present invention, there is provided a reaction furnace for producing polycrystalline silicon by a zinc reduction method, which can prevent precipitation of polycrystalline silicon in a furnace wall and a discharge pipe of the reaction furnace. can do. Further, according to the present invention, after one batch process is completed, the inner tube for the discharge pipe is removed, and the inner vessel (the inner vessel and the silicon carbide rod when the silicon carbide rod is installed) is reacted. Take it out of the furnace, install another insertion vessel (if a silicon carbide rod is installed, an insertion vessel and a silicon carbide rod), and install another intubation tube for the discharge pipe. Since the process can be performed, the production efficiency is increased.

It is a typical end view which shows the example of the form of the reaction furnace for the polycrystalline silicon manufacture of this invention. It is an end elevation which shows the insertion container in FIG. It is the typical end elevation which expanded the vicinity of the discharge pipe of the reactor for polycrystalline silicon manufacture of this invention. 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. It is the typical end elevation which expanded the vicinity of the discharge pipe of the reactor for polycrystalline silicon manufacture of this invention. It is a typical end view which shows the example of a form by which the silicon carbide stick | rod is installed in the insertion container among the reactors for polycrystalline silicon manufacture of this invention. It is an end elevation which shows the insertion container and silicon carbide rod in FIG. It is a typical end view which shows the example of a form by which the silicon carbide stick | rod is installed in the insertion container among the reactors for polycrystalline silicon manufacture of this invention. It is a typical end view which shows the example of a form by which the silicon carbide stick | rod is installed in the insertion container among the reactors 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. It is a typical end view of a reaction furnace of a comparative example in which only an intubation tube is installed in the discharge pipe. It is a typical end view of the reactor of the comparative example with which the intubation tube is not connected with the insertion container. It is a typical end view of a reactor of a comparative example in which an intubation tube enters the inside of a discharge port of the insertion vessel, although the intubation tube is connected to the insertion vessel.

  The 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 a view showing the insertion container in FIG. 1, and (2-1) is an end view showing the insertion container in FIG. 1, and is an end view when cut in the vertical direction. Yes, (2-2) is a view of the part surrounded by the two-dot chain line in (2-1) (the part indicated by the symbol A in the figure) as seen from the outside of the insertion container. FIG. 3 is an enlarged schematic end view of the vicinity of the discharge pipe of the reactor for producing polycrystalline silicon according to the present invention, and shows a state in which the internal pipe for the discharge pipe is inserted into the discharge pipe. . FIGS. 4 and 5 are schematic diagrams showing examples of the installation positions and shapes of the supply pipe for silicon tetrachloride vapor and the supply pipe for zinc vapor, and (4-1) and FIG. 5 in FIG. It is a figure when the supply pipe | tube of a silicon tetrachloride vapor | steam and the supply pipe | tube of a zinc vapor | steam are seen from upper side, (4-2) of FIG. 4 is an end elevation when cut in the perpendicular direction. FIG. 6 is a schematic end view enlarging the vicinity of the discharge pipe of the reactor for producing polycrystalline silicon according to the present invention, showing the flow of nitrogen gas in the reactor. 4 and 5, for convenience of explanation, only the reactor insertion vessel, the silicon tetrachloride vapor supply pipe, and the zinc vapor supply pipe are shown.

  In FIG. 1, a reaction furnace 20 includes a side wall part 1 having a vertically long cylindrical shape, a lid part 2 (2a, 2b) that closes the upper and lower sides of the side wall part 1, and a heater 5 for heating the reaction furnace 20; It consists of. In the reaction furnace 20, an insertion container 13 having a cylindrical side surface and a circular bottom surface is installed. A silicon tetrachloride vapor supply pipe 7 for supplying silicon tetrachloride vapor 9 into the insertion vessel 13 and a zinc vapor 10 into the insertion vessel 13 are provided at the upper part of the reaction furnace 20. A zinc vapor supply pipe 8 is attached. A discharge pipe 6 for discharging the exhaust gas 11 discharged from the insertion container 13 to the outside of the reaction furnace is attached to the lower part of the reaction furnace 20. A discharge pipe inner intubation 14 is installed in the discharge pipe 6. The reaction furnace 20 is provided with a nitrogen gas supply pipe 151 for supplying nitrogen gas 16 into the reaction furnace 20. The side wall portion 1 and the lid portion 2 are sealed by, for example, sandwiching a sealing material between the respective flange portions and bolting the flange portions together.

  As shown in (2-1) of FIG. 2, a disc-shaped insertion container lid 18 is installed on the upper side of the insertion container 13. A silicon tetrachloride vapor supply pipe insertion port 21 and a zinc vapor supply pipe insertion port 22 are formed. A discharge port 17 for discharging the exhaust gas 11 from the inside of the insertion container 13 is formed in the lower part of the insertion container 13. As shown in (2-2) of FIG. 2, an exhaust gas leakage prevention wall 15 is formed on the outer wall of the insertion container 13 so as to surround the discharge port 17. The exhaust gas leakage prevention wall 15 is formed so as to protrude outward from the outer wall of the insertion container 13. In the embodiment shown in FIGS. 1 and 2, a cylindrical exhaust gas leakage prevention wall is formed on the outer wall side of the insertion container so as to surround the discharge port of the insertion container.

  As shown in FIG. 3, the exhaust pipe inner tube 14 is inserted into the exhaust pipe 6 from the outside of the reaction furnace. At this time, the inner pipe 14 for the exhaust pipe is inserted inside the exhaust pipe 6 until the leak prevention wall 15 of the exhaust gas enters the inside of the inner pipe 14 for the exhaust pipe. Therefore, the position of the end 141 of the exhaust gas leakage prevention wall 15 (the end of the exhaust gas leakage prevention wall 15 opposite to the side connected to the outer wall of the insertion container 13) is From the position of the tube end 142 of the discharge tube inner tube 14 (the tube end of the discharge tube inner tube 14 on the inner container 13 side), it is inside the tube of the discharge tube inner tube 14. In other words, the opening 143 of the exhaust gas leakage prevention wall 15 on the outlet side of the exhaust gas is in the pipe of the internal pipe 14 for the exhaust pipe.

  A gap 161 is formed between the exhaust pipe inner tube 14 and the exhaust gas leakage prevention wall 15, and the pipe end 142 of the exhaust pipe inner tube 14 and the inner container 13 A gap 162 is formed between them. Therefore, the inner tube 14 for the discharge tube is inserted into the discharge tube 6 to a position where a gap 162 is formed between the tube end 142 of the inner tube 14 for the discharge tube and the inner container 13. .

  Further, a nitrogen gas pipe fixing member 4 is installed so as to be hooked on a furnace collar 12 formed on the inner wall of the side wall 1, and the nitrogen gas pipe fixing member 4 includes the nitrogen gas. A supply pipe 151 is fixed.

  One end of the supply pipe 7 for the silicon tetrachloride vapor is located inside the insertion container 13 and the other end is connected to a silicon tetrachloride evaporator. One end of the zinc vapor supply pipe 8 is located inside the insertion container 13 and the other end is connected to a zinc evaporator. Further, the exhaust pipe 6 serves as a recovery device for recovering exhaust gas 11, that is, zinc chloride gas generated when silicon tetrachloride reacts with zinc and silicon tetrachloride vapor and zinc vapor which are unreacted gases. It is connected. In addition, the discharge pipe inner intubation 14 is connected to the recovery device in the same manner as the discharge pipe 6.

  A method for producing polycrystalline silicon using the reactor 20 will be described. First, the reaction furnace 20 is heated by the heater 5, silicon tetrachloride and zinc are vaporized by respective evaporators, and silicon tetrachloride vapor 9 is supplied from a silicon tetrachloride vapor supply pipe 7 to zinc vapor 10 The exhaust gas 11 is discharged from the discharge pipe 6 to the outside of the reaction furnace 20 while supplying the gas from the zinc vapor supply pipe 8 into the insertion container 13. At this time, in the insertion container 13, silicon tetrachloride and zinc react to generate polycrystalline silicon, and the generated polycrystalline silicon precipitates in the insertion container 13. Since silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the insertion container 13 and the exhaust gas 11 is discharged from the lower part of the insertion container 13, the silicon tetrachloride vapor and the zinc vapor are The raw material vapor moves downward from the upper portion of the insertion vessel 13 and reacts in the insertion vessel 13 to grow polycrystalline silicon crystals. In addition, zinc chloride is also generated by the reaction of silicon tetrachloride and zinc, but the zinc chloride gas is discharged as an exhaust gas 11 together with unreacted silicon tetrachloride vapor and zinc vapor. The gas is discharged from the reaction furnace 20 through the inside of the discharge pipe inner tube 14 from 17.

  During the reaction between silicon tetrachloride and zinc, nitrogen gas 16 is supplied from the nitrogen gas supply pipe 151 into the reaction furnace 20.

That is, the reactor for producing polycrystalline silicon according to the present invention is a reactor for producing polycrystalline silicon by reacting silicon tetrachloride and zinc,
An insertion vessel is installed in the reaction furnace, and an exhaust gas discharge port is formed in the lower part of the insertion vessel. An exhaust gas surrounding the discharge port is formed on the outer wall of the insertion vessel. Leakage prevention wall is formed,
A silicon tetrachloride vapor supply pipe for supplying silicon tetrachloride vapor into the insertion vessel and a zinc vapor supply tube for supplying zinc vapor into the insertion vessel are provided at the top of the reactor. And
At the bottom of the reactor, has a discharge pipe for discharging exhaust gas,
The reaction furnace has an inert gas supply pipe for supplying an inert gas in the reaction furnace,
In the discharge pipe, an intubation for the discharge pipe is installed,
The exhaust gas leakage prevention wall enters the inside of the exhaust pipe intubation, and between the exhaust pipe intubation and the exhaust gas leakage prevention wall, and the pipe end of the exhaust pipe intubation and the pipe A gap is formed between the insertion container and
Is a reactor for producing polycrystalline silicon.

  Since the temperature in the reaction furnace is about 1,000 ° C., examples of the material of the reaction furnace include quartz such as transparent quartz and opaque quartz, silicon carbide, silicon nitride, and the like. Silicon nitride is preferred, and quartz and silicon nitride are preferred from the viewpoint that cracks due to temperature gradients are unlikely to occur. Further, depending on the structure of the reaction furnace and the like, the material of the reaction furnace is not particularly limited as long as it can withstand the heating temperature during the reaction. Further, the wall portion and the lid portion of the reactor may be made of different materials.

  Examples of the material for the insertion container include quartz such as transparent quartz, opaque quartz, and sintered quartz, silicon carbide, silicon nitride, etc., and silicon carbide, because it has a long life and is easy to handle when removing precipitated polycrystalline silicon. Silicon nitride is preferred, and quartz and silicon nitride are preferred from the viewpoint that cracks due to temperature gradients are unlikely to occur.

  The shape of the reaction furnace and the insertion vessel is such that silicon tetrachloride vapor and zinc vapor supplied into the insertion vessel from the upper part of the insertion vessel in the reaction furnace are lower than the upper part of the insertion vessel. It is a shape that reacts while moving downward toward the surface, that is, a vertically long shape. In other words, the shape of the reaction furnace and the insertion vessel is such that the raw material vapor and the exhaust gas flow from the upper part to the lower part of the insertion vessel in the reaction furnace.

  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. Further, the size of the insertion vessel is not particularly limited as long as it does not damage the side wall of the reactor and can fit within the reactor.

  In the reaction furnace, 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 reaction furnace, a downward flow of the raw material vapor is formed in the insertion vessel installed in the reaction furnace, and a reaction between silicon tetrachloride and zinc is caused in the insertion vessel. The silicon tetrachloride vapor supply pipe, the zinc vapor supply pipe, and the discharge pipe are attached at a position where the silicon tetrachloride vapor can be formed (position in the vertical direction). In FIG. 1, it is described that the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 are inserted from the lid portion 18 of the insertion container into the insertion container. Alternatively, for example, the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 may be inserted from the side surface of the insertion container 13 into the inside.

  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 rotate in the insertion container.

  Inside the discharge pipe, the internal pipe for the discharge pipe is installed. The exhaust gas passes through the inside of the exhaust gas leakage prevention wall from the discharge port of the insertion container, passes through the inside of the exhaust pipe, and is discharged to the outside of the reactor. An intubation tube for the discharge pipe is installed in the discharge pipe.

  The exhaust pipe intubation has a gap formed between the exhaust pipe intubation and the exhaust gas leakage prevention wall, and between the end of the exhaust pipe intubation and the insertion container. It is installed in the discharge pipe so that a gap is formed. In the reactor for producing polycrystalline silicon according to the present invention, when an inert gas such as nitrogen gas 16 is supplied into the reactor from an inert gas supply tube such as the nitrogen gas supply tube, as shown in FIG. In addition, the nitrogen gas 16 first flows through a gap 163 between the insertion vessel 13 and the side wall 1 of the reactor, and then the nitrogen gas 16 passes through the exhaust pipe 6 and the exhaust pipe inner tube. 14 and the gap 162 between the pipe end 142 of the inner tube 14 for the discharge pipe and the outer wall of the inner container 13 and the leakage prevention of the inner pipe 14 for the discharge pipe and the exhaust gas. The nitrogen gas that has flowed into the inner tube 14 for the discharge pipe through the gap 161 between the wall 15 and the nitrogen gas that has flowed into the gap 165 passes through the gap 165 and goes out of the reactor. And is discharged through the gap 162 and the gap 161. , Nitrogen gas flowing into the outlet pipe for intubation 14, together with said discharge gas 11 is discharged through the outlet in the pipe cannulae 14 out of the reactor.

  Examples of the material for the inner tube for the exhaust pipe include quartz such as transparent quartz, opaque quartz, and sintered quartz, silicon carbide, silicon nitride, etc. When removing polycrystalline silicon deposited in the inner pipe for the exhaust pipe In view of easy handling, silicon carbide and silicon nitride are preferable, and quartz and silicon nitride are preferable from the viewpoint that cracking due to a temperature gradient is difficult to occur. Moreover, it is preferable that the material of the inner tube for the discharge tube is the same as the material of the inner tube from the viewpoint that problems caused by the difference in expansion rate from the inner tube are less likely to occur.

A heat insulating material may be disposed between the discharge pipe and the internal pipe for discharge pipe (gap 165 in FIG. 6). Since the temperature inside the reaction furnace is about 1000 ° C., the temperature of the exhaust gas vented through the exhaust pipe is also about 1000 ° C., and between the insertion vessel and the side wall of the reaction furnace Since the temperature of the gas passing through the gap (gap 163 in FIG. 6) is also about 1000 ° C., it is necessary to have heat resistance that can withstand the temperature of these gases. Further, even if the gap between the exhaust pipe and the internal pipe for the exhaust pipe becomes small due to the difference in thermal expansion between the exhaust pipe and the internal pipe for the exhaust pipe, the heat insulating material A material that is easily compressible and deformed is preferable so that the inner tube for the discharge tube is not damaged. It is preferable that the material is made of an oval structure (a structure in which granular materials are aggregated) and can be compressed and deformed. Moreover, the structure of the heat insulating material may be a structure that allows gas to permeate inside or a structure that does not permeate gas. Examples of the material for the heat insulating material include quartz wool, calcium silicate fiber, alumina fiber, silica alumina fiber, and carbon fiber. Of these, quartz wool and calcium silicate fiber are preferable. The material of the heat insulating material may be a single type or a combination of two or more types.
Moreover, a cylindrical hard heat insulating material (hereinafter also referred to as a hard heat insulating material) is disposed between the discharge pipe and the internal pipe for the discharge pipe (gap 165 in FIG. 6), and the hard heat insulation. You may arrange | position the heat insulating material which can be compressively deformed in the clearance gap between a material and this discharge pipe, and the clearance gap between this hard heat insulating material and this internal pipe for discharge. At this time, the thickness, outer diameter, and inner diameter of the hard heat insulating material are the difference in thermal expansion between the hard heat insulating material, the discharge pipe, and the inner tube for the discharge pipe, and are between the hard heat insulating material and the discharge pipe. The thickness, the outer diameter, and the inner diameter are appropriately selected so that the discharge pipe and the discharge pipe inner tube are not damaged even if the gap and the gap between the hard heat insulating material and the discharge pipe inner pipe are reduced. As the material of the hard heat insulating material, the temperature of the gas passing through the gap (gap 163 in FIG. 6) between the insertion vessel and the side wall of the reactor is about 1000 ° C. From the point that it has heat resistance that can withstand the temperature of the gas and has low thermal conductivity and excellent heat insulation properties, examples include opaque quartz, sintered quartz, porous carbon, porous alumina, porous silica alumina, calcium silicate, Of these, sintered quartz, porous alumina, porous silica alumina, and calcium silicate are preferred.

  Although the thickness of this heat insulating material is suitably selected by the kind of heat insulating material, the heat insulation requested | required, etc., Preferably it is 10-300 mm, Most preferably, it is 50-200 mm. The thickness of the heat insulating material may be a thickness that completely fills a space between the discharge pipe and the internal pipe for the discharge pipe during the reaction, or between the discharge pipe and the heat insulating material during the reaction, or The thickness may be such that a gap remains between the inner pipe for the discharge pipe and the heat insulating material.

  The inner diameter of the inner pipe for the exhaust pipe is appropriately selected according to the material and outer diameter of the exhaust gas leakage prevention wall, and the inert gas that has passed through the gap between the inner container and the side wall of the reaction furnace. A portion of the exhaust pipe can pass through the exhaust pipe intubation and the exhaust gas leakage prevention wall into the exhaust pipe intubation, and during the reaction, the exhaust pipe intubation and the exhaust When the gas leakage prevention wall is thermally expanded, a gap that does not damage the exhaust pipe intubation tube or the exhaust gas leakage prevention wall due to a difference in thermal expansion amount is formed between the exhaust pipe intubation tube and the exhaust gas leakage prevention wall. Any size may be used as long as it is formed between the two.

  The outer diameter of the inner tube for the discharge pipe is appropriately selected depending on the material and inner diameter of the discharge pipe, and when the discharge pipe and the inner pipe for the discharge pipe are thermally expanded during the reaction, It is sufficient that the gap that does not damage the tube or the inner tube for the discharge tube is of a size that is formed between the discharge tube and the inner tube for the discharge tube.

  When the heat insulating material is not disposed between the discharge pipe and the discharge pipe inner tube, the size of the gap between the discharge pipe and the discharge pipe inner tube (the gap 165 in FIG. 6). And corresponds to the distance between the inside of the exhaust pipe 6 and the outside of the internal pipe 14 for the exhaust pipe.)) When the exhaust pipe and the internal pipe for the exhaust pipe are thermally expanded during the reaction. The discharge pipe or the intubation pipe for the discharge pipe may be of a size that is not damaged due to the difference in the amount of expansion, and is appropriately selected, but is preferably 1 to 40 mm in size during reaction, and particularly preferably during reaction. It is 2-20 mm in size. Further, when the heat insulating material is disposed between the discharge pipe and the inner pipe for the discharge pipe, the size of the gap between the discharge pipe and the inner pipe for the discharge pipe (of the discharge pipe 6 The distance between the inner side and the outer side of the inner tube 14 for the discharge pipe is preferably 10 to 300 mm in the reaction size, and particularly preferably 50 to 200 mm in the reaction size.

  The size of the gap between the exhaust pipe inner tube and the exhaust gas leakage prevention wall (in FIG. 6, the size of the gap 161, and the inside of the exhaust pipe inner tube 14 and the leakage prevention of the exhaust gas) This corresponds to the distance from the outside of the wall 15.) and the size of the gap between the tube end of the inner tube for the discharge tube and the inner container (the size of the gap 162 in FIG. (This corresponds to the distance between the tube end 142 of the tube inner tube 14 and the outer wall of the inner vessel 13.) The inert gas that has passed through the gap between the inner vessel and the side wall of the reactor. A part flows between the inner pipe for the exhaust pipe and the leakage prevention wall of the exhaust gas and between the pipe end of the inner pipe for the exhaust pipe and the inner container and into the inner pipe for the exhaust pipe. And when the inner pipe for the exhaust pipe and the leakage prevention wall for the exhaust gas are thermally expanded during the reaction, the exhaust is caused by the difference in thermal expansion amount. The inner intubation or the leakage prevention wall of the exhaust gas may be of a size that is not damaged, and is appropriately selected. The reaction size is preferably 1 to 40 mm, and particularly preferably the reaction size. 2-20 mm.

  In the reaction furnace for producing polycrystalline silicon according to the present invention, the discharge port for discharging the exhaust gas to the outside is formed in the lower portion of the insertion vessel, and the discharge port of the insertion vessel is provided. A wall for preventing leakage of the exhaust gas is formed on the outer wall side of the insertion container so as to surround. And, in the reactor for producing polycrystalline silicon according to the present invention, the exhaust pipe intubation is installed so that the exhaust gas leakage preventing wall enters the inside of the exhaust pipe internal intubation. Preventing exhaust gas discharged from the inner vessel from flowing into the gap between the inner vessel and the side wall of the reactor and the gap between the outlet pipe and the inner pipe for the outlet pipe. Can do.

  Referring to FIG. 6 in detail, as shown in FIG. 6, the exhaust gas leakage prevention wall 15 enters the inside of the exhaust pipe internal intubation tube 14, thereby causing the exhaust gas leakage prevention wall 15. 15, that is, the position at which the exhaust gas 11 is discharged from the inner container 13 is located on the inner side of the inner pipe 14 of the exhaust pipe from the position of the pipe end 142 of the inner pipe 14 for the exhaust pipe. become. Therefore, the exhaust gas 11 passes through a gap 161 between the exhaust pipe inner tube 14 and the exhaust gas leakage prevention wall 15 in the discharge direction of the exhaust gas 11 (the exhaust gas 11 indicated by an arrow in FIG. 6). As long as the flow does not flow in the opposite direction, the exhaust gas 11 will flow into the gap 163 between the inner vessel 13 and the side wall 1 of the reactor and the exhaust pipe 6 and the inner pipe for the exhaust pipe. 14 is structured so that it cannot flow into the gap 165 between them. At the time of the reaction, a flow of a large amount of the exhaust gas 11 is formed from the inside of the inner container 13 through the inner tube 14 for the exhaust pipe and out of the reaction furnace. It is difficult for reverse flow to occur. Therefore, it becomes difficult for the exhaust gas 11 to flow through the gap 161 in the direction opposite to the discharge direction of the exhaust gas 11. In addition, since it is attracted by the flow of a large amount of exhaust gas 11 during the reaction, the gap 163 between the inner container 13 and the side wall 1 of the reaction furnace is inward of the inner pipe 14 for the exhaust pipe. The gas in the gap 163 easily flows through the gap 162 and the gap 161. Furthermore, by pressurizing with inert gas from the gap 163 side between the insertion vessel 13 and the side wall portion 1 of the reactor, the discharge from the pipe of the discharge pipe inner pipe 14 to the gap 163 side is performed. It becomes difficult for the gas 11 to flow. For these reasons, in the reaction furnace for producing polycrystalline silicon according to the present invention, the exhaust gas discharged from the insertion container is a gap between the insertion container and the side wall of the reaction furnace and the discharge pipe. Can be prevented from flowing into the gap between the inner tube and the inner tube for the discharge tube. Therefore, in the reactor for producing polycrystalline silicon according to the present invention, silicon is not deposited on the side wall of the reactor and the exhaust gas exhaust pipe.

  The length of the exhaust gas leakage prevention wall entering the pipe of the exhaust pipe inner tube (in FIG. 6, from the pipe end 142 of the exhaust pipe inner tube 14 to the end 141 of the exhaust gas leakage prevention wall 15) Is suitably selected, but is preferably 1 to 100 mm in the length during the reaction, and particularly preferably 2 to 50 mm in the length during the reaction.

  Further, if the temperature in the exhaust pipe intubation becomes too low, unreacted zinc in the exhaust gas is condensed in the exhaust pipe intubation. Therefore, when the temperature in the inner tube for the discharge pipe becomes too low, the discharge pipe needs to be externally heated in order to prevent condensation of unreacted zinc. When the discharge pipe is short, the temperature in the internal pipe for the discharge pipe does not become too low, so it is not necessary to heat the discharge pipe, or the heat of the heater for heating the reactor Since the entire discharge pipe is heated, a heater dedicated to the discharge pipe is not necessary. On the other hand, depending on the installation position of the recovery device for recovering zinc chloride gas, silicon tetrachloride vapor and zinc vapor in the latter stage, the discharge pipe becomes long, so the temperature in the internal pipe for the discharge pipe becomes too low There is. In this case, a heater dedicated to the discharge pipe is required.

  Therefore, by disposing the heat insulating material between the discharge pipe and the inner pipe for the discharge pipe, the temperature in the inner pipe for the discharge pipe becomes too low, and unreacted zinc is condensed in the inner pipe for the discharge pipe. Can be prevented. Therefore, since the heat insulating material is disposed between the discharge pipe and the internal insertion pipe for the discharge pipe, it is not necessary to externally heat the discharge pipe. Furthermore, since it is not necessary to heat the discharge pipe externally, the temperature of the pipe end of the discharge pipe on the connection side with the subsequent collection device can be lowered. Therefore, it is possible to install a resin packing at a connection site between the subsequent-stage recovery device and the pipe end of the discharge pipe, and to seal between the subsequent-stage recovery apparatus and the pipe end of the discharge pipe. Therefore, it is possible to improve the sealing property between the subsequent collection device and the pipe end of the discharge pipe.

  Further, since the heat insulating material is disposed between the exhaust pipe and the internal pipe for the exhaust pipe, the exhaust gas discharged from the internal container is transferred to the side wall of the internal container and the reactor. And the effect of preventing the air from flowing into the gap between the discharge pipe and the gap between the discharge pipe and the inner pipe for the discharge pipe can be enhanced. This will be described in detail with reference to FIG. When the heat insulating material is disposed in the gap 165, the nitrogen gas 16 in the gap 163 is prevented from flowing into the gap 165, and thus the gap 162 and the gap without resistance by the heat insulating material are prevented. It becomes easy to flow toward 161. Therefore, the flow of the nitrogen gas 16 makes it difficult for the exhaust gas 11 to flow from the inside of the inner tube 14 for the discharge tube to the gap 163 side.

  Further, since the heat insulating material is disposed between the exhaust pipe and the internal pipe for the exhaust pipe, the high-temperature gas passing through the gap between the internal container and the side wall of the reactor However, since it becomes difficult to flow between the discharge pipe and the inner pipe for the discharge pipe, the temperature of the discharge pipe is lowered, and the temperature of the pipe end of the discharge pipe on the connection side with the subsequent recovery device is lowered. be able to. Therefore, it is possible to install a resin packing at a connection site between the subsequent-stage recovery device and the pipe end of the discharge pipe, and to seal between the subsequent-stage recovery apparatus and the pipe end of the discharge pipe. Therefore, it is possible to improve the sealing property between the subsequent collection device and the pipe end of the discharge pipe.

  Therefore, even if there is a gap between the heat insulating material and the discharge pipe or the internal pipe for the discharge pipe during the reaction, the heat insulating material is disposed between the insertion container and the side wall of the reaction furnace. By providing the exhaust gas discharged from the insertion vessel, a gap between the insertion vessel and the side wall of the reaction furnace and a gap between the discharge pipe and the inner pipe for the discharge pipe are provided. Can be prevented from flowing into, and the sealing between the recovery device in the subsequent stage and the pipe end of the discharge pipe can be improved, but the exhaust gas discharged from the insertion container is The point that the effect of preventing inflow into the gap between the inner vessel and the side wall of the reactor and the gap between the discharge pipe and the inner pipe for the discharge pipe is enhanced, and the subsequent-stage recovery device From the point that the effect of enhancing the sealing between the pipe and the pipe end of the discharge pipe is enhanced, the heat insulating material during the reaction and the discharge pipe or the Preferably as the gap is small between the inside for delivering pipes intubation, it is particularly preferred that between the exhaust extraction tube and the outlet in the pipe intubation is the thermal insulation material is arranged to completely fill during the reaction.

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

  In FIG. 1, it is described that the in-furnace collar portion 12 is formed on the upper side of the side wall portion 1 and the fixing member 4 for the nitrogen gas pipe is installed. In the reactor, when the fixing member 4 of the nitrogen gas pipe is not used, the in-furnace collar portion 12 may not be formed.

  In the reactor for producing polycrystalline silicon according to the present invention, an inert gas such as nitrogen gas is supplied into the reactor from the inert gas supply pipe, whereby the inert gas is supplied to the side wall of the reactor. And a gap between the exhaust gas exhaust pipe and the exhaust pipe internal intubation, a gap between the internal container and the pipe end of the exhaust pipe internal intubation and the exhaust An inert gas such as nitrogen gas is allowed to flow through the gap between the pipe inner pipe and the exhaust gas leakage prevention wall, and the gap between the side wall of the reactor and the inner vessel and the exhaust gas discharge pipe It is possible to prevent the exhaust gas from flowing into the gap between the internal pipe for the exhaust pipe.

  Using the reaction furnace for producing polycrystalline silicon according to the present invention, silicon tetrachloride vapor and zinc vapor are supplied into the insertion container from the upper part of the insertion container installed in the reaction furnace. Polycrystalline silicon can be produced by discharging exhaust gas from the discharge port formed in the lower part of the container and reacting silicon tetrachloride vapor with zinc vapor in the insertion container. At this time, the exhaust gas is discharged from the discharge port of the insertion container to the outside of the reaction furnace through the inside of the discharge pipe inner tube.

  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 contact gently in the reactor, preferably when they contact at a linear velocity of 5 cm / second or less, dendritic, needle-like or plate-like polycrystalline silicon is produced. 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, in the method for 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 insertion vessel, that is, a diameter of 3 μm. Silicon tetrachloride vapor and zinc vapor are supplied into the insertion vessel under the condition that the following fine-grained polycrystalline silicon is difficult to produce. In other words, in the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, the silicon tetrachloride vapor is supplied under the supply conditions of the raw material vapor in which dendritic, needle-like or plate-like polycrystalline silicon is easily generated. And zinc vapor are fed into the insertion vessel. The supply conditions of the raw material vapor from which dendritic, needle-like, or plate-like polycrystalline silicon is easily generated are appropriately selected depending on the size of the reaction furnace and the insertion vessel.

  The supply ratio (molar ratio) of silicon tetrachloride vapor to zinc vapor is silicon tetrachloride vapor: zinc vapor = 0.7: 2 to 1.2: 2, preferably 0.8: 2 to 1.2. : 2 and particularly preferably 0.9: 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 becomes possible to deposit polycrystalline silicon stably.

  In the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, silicon tetrachloride vapor and zinc vapor are moved downward, and the reaction between silicon tetrachloride and zinc is carried out in the insertion vessel. To deposit polycrystalline silicon in the insertion vessel to grow crystals.

  Further, in the method for producing polycrystalline silicon using the reaction furnace for producing polycrystalline silicon according to the present invention, as shown in FIG. 1, a supply pipe for an inert gas such as nitrogen gas is attached to the reaction furnace. An active gas is supplied into the reactor. In the present invention, by supplying an inert gas into the reaction furnace, it is possible to prevent outside air from entering the reaction furnace, and to pass the inert gas between the side wall of the reaction furnace and the insertion vessel. A gap between the exhaust pipe and the inner pipe for the exhaust pipe, a gap between the inner container and the pipe end of the inner pipe for the exhaust pipe, and the inner pipe for the exhaust pipe and the exhaust gas An inert gas is allowed to flow through the gap between the leakage prevention wall and the gap between the side wall of the reactor and the insertion vessel and the gap between the exhaust gas exhaust pipe and the exhaust pipe insertion pipe. The exhaust gas can be prevented from flowing in.

  As for the supply amount and pressure of the inert gas, the exhaust gas flows into the gap between the side wall of the reactor and the insertion vessel and the gap between the discharge pipe for the exhaust gas and the insertion pipe for the discharge pipe. As long as the supply amount and pressure can prevent this, there is no particular limitation, and it is appropriately selected. Then, the supply amount and pressure of the inert gas supplied into the reaction furnace are selected, and the pressure in the gap between the insertion vessel and the side wall of the reaction furnace is compared with the pressure in the inner pipe for the discharge pipe. , 0.01 kPa or more is preferable, and 0.01 to 5 kPa is particularly preferable.

  In the method for producing polycrystalline silicon using the reaction furnace for producing polycrystalline silicon according to the present invention, an inert gas supply pipe is attached to the reaction furnace, and the inert gas is supplied into the reaction furnace. As shown in FIG. 1, an inert gas may be supplied from the lid portion 2a on the upper side of the reaction furnace 20, or, for example, a plurality of attached to the lid portion 2a on the upper side of the reaction furnace 20 may be used. The inert gas may be supplied through an inert gas supply pipe of the above, or the inert gas attached to the lid portion 2a on the upper side of the reaction furnace 20 and the lid portion 2b on the lower side of the reaction furnace 20 An inert gas may be supplied through a supply pipe.

  In the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, the production of polycrystalline silicon is terminated by stopping the supply of silicon tetrachloride vapor and zinc vapor. After cooling the reaction furnace, first, the inner pipe for the discharge pipe is removed, and then the inner container with polycrystalline silicon deposited therein is taken out of the reaction furnace. For example, in the embodiment shown in FIG. 1, the discharge pipe inner tube 14 is removed, and then the attached members such as the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 are removed, and then the reactor 20 The lower lid portion 2 b is opened, and the insertion container 13 is taken out from the lower side of the side wall portion 1. Then, the deposited polycrystalline silicon is scraped out of the insertion container to obtain polycrystalline silicon.

  The insertion container after the polycrystalline silicon is scraped and the inner tube for the discharge pipe are used again in the production of polycrystalline silicon. Further, before the reuse, the inner vessel or the inner tube for the discharge tube may be washed with pure water or an acid such as hydrochloric acid, nitric acid, hydrofluoric acid or the like.

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

  Of the reaction furnace for producing polycrystalline silicon according to the present invention, an embodiment in which a silicon carbide rod is installed as a precipitation rod in the insertion vessel will be described with reference to FIGS. In the following description, only points different from the embodiment in which no precipitation rod is installed in the insertion container will be described, and the same points will be omitted. FIG. 7, FIG. 9 and FIG. 10 are schematic end views showing an embodiment in which a silicon carbide rod is installed in an insertion vessel in the reactor for producing polycrystalline silicon according to the present invention. FIG. 8 is an end view showing the insertion container and the silicon carbide rod in FIG. 7, and is an end view when cut in the horizontal direction. For convenience of explanation, only the insertion container and the silicon carbide rod are shown in FIG.

  The embodiment shown in FIG. 7 is an embodiment in which the silicon carbide rod is installed in the insertion container by inserting the silicon carbide rod from above the fixing member of the nitrogen gas pipe. In the reaction furnace 30a shown in FIG. 7, the silicon carbide rod 3 is directed from the top to the bottom into the insertion container 13 through the nitrogen gas fixing member 4 and the insertion opening opened in the lid 18 of the insertion container. It is installed in the insertion container 13 so as to protrude. The silicon carbide rod 3 may be fixed to the fixing member 4 of the nitrogen gas pipe, or may be fixed to the lid portion 18 of the insertion container.

  The embodiment shown in FIG. 9 is an embodiment in which the silicon carbide rod is installed in the insertion vessel by fixing the silicon carbide rod to the bottom of the insertion vessel. In the reaction furnace 30 b shown in FIG. 9, the silicon carbide rod 3 is fixed to the bottom of the insertion vessel 13. The silicon carbide rod 3 is installed in the insertion container 13 so as to protrude from the bottom to the top in the insertion container 13.

  The embodiment shown in FIG. 10 is an embodiment in which the silicon carbide rod is fixed to the lid portion of the insertion container and installed in the insertion container. In the reaction furnace 30c shown in FIG. 10, the silicon carbide rod 3 is fixed to the lid 18 of the insertion container, and protrudes into the insertion container 13 from the top to the bottom. It is installed inside.

  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 silicon carbide rod existing between the lower side of the lid portion 18 of the insertion container and the upper side of the discharge pipe 6 is such that the length of the discharge pipe 6 extends from the lower side of the lid portion 18 of the insertion container. 20 to 120% is preferable, 40 to 100% is particularly preferable, and 50 to 90% is more preferable with respect to the length in the vertical direction up to the upper side.

  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 in the case of a porous silicon carbide rod not impregnated with silicon, when it is installed in the insertion vessel and a reaction between silicon tetrachloride vapor and zinc vapor is performed, at the initial stage of the reaction, In the porous structure near the outside of the silicon carbide rod, contact between the silicon tetrachloride vapor and the zinc vapor occurs, and silicon is generated there, so that the outside of the silicon carbide rod is impregnated with silicon in the pores. 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 the silicon carbide rod is not particularly limited. For example, when there are four silicon carbide rods (precipitation rods), the silicon carbide rods 3 are installed at equal intervals on an arc centered on the center of the insertion vessel 13 as shown in FIG. It is preferable. 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.

  A method for producing polycrystalline silicon using the reaction furnace 30a, the reaction furnace 30b, and the reaction furnace 30c will be described. First, the inner vessel 13 and the silicon carbide rod 3 are installed in a reaction furnace, and then the inner tube 14 for the discharge pipe is installed, and then the reactors 30a, 30b, 30c are heated by the heater 5. Next, silicon tetrachloride and zinc are vaporized by the respective evaporators, and silicon tetrachloride vapor 9 is supplied from the silicon tetrachloride vapor supply pipe 7 and zinc vapor 10 is supplied from the zinc vapor supply pipe 8 to the inner vessel. The exhaust gas 11 is discharged from the discharge pipe 6 to the outside of the reaction furnaces 30a, 30b, 30c while being supplied into the interior of the reactor 13. At this time, in the insertion container 13, silicon tetrachloride reacts with zinc to produce polycrystalline silicon, but since the silicon carbide rod 3 is installed in the insertion container 13, The 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 insertion container 13 and the exhaust gas 11 is discharged from the lower part of the insertion container 13, the silicon tetrachloride vapor and the zinc vapor are Since the silicon carbide rod 3 is moving downward from the upper portion of the insertion vessel 13 and along the flow, a polycrystalline silicon crystal grows so as to cover the silicon carbide rod 3. . In addition, although zinc chloride is also generated by the reaction of silicon tetrachloride and zinc, the zinc chloride gas is used as exhaust gas 11 together with unreacted silicon tetrachloride vapor and zinc vapor, and the inside of the exhaust pipe in the exhaust pipe 6. It passes through the intubation 14 and is discharged outside.

  In the method for producing polycrystalline silicon using the reaction furnace for producing polycrystalline silicon according to the present invention, a precipitation rod is installed in the insertion vessel, and the polycrystalline silicon produced while reacting silicon tetrachloride vapor with zinc vapor is produced. Crystalline silicon may be deposited on the deposition rod.

  Of the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, a precipitation rod is installed in the insertion vessel, and the silicon tetrachloride vapor and the zinc vapor are reacted while being produced. An embodiment in which polycrystalline silicon is deposited on the deposition rod will be described. In the following, only the points different from the embodiment in which the reaction of silicon tetrachloride vapor and zinc vapor is performed in the insertion vessel without installing a precipitation rod in the insertion vessel will be described, and similar points will be described. Omitted.

  Of the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, the precipitation rod is installed in the insertion vessel and produced while reacting silicon tetrachloride vapor with zinc vapor. As a reaction furnace for performing an embodiment in which polycrystalline silicon is deposited on the precipitation rod, among the reaction furnaces for producing polycrystalline silicon of the present invention, a silicon carbide rod is used as the precipitation rod in the insertion vessel. Examples of installed modes include the reaction furnace 30a, the reaction furnace 30b, and the reaction furnace 30c.

  The precipitation rod and the silicon carbide rod according to the method for producing polycrystalline silicon using a reactor for the production of polycrystalline silicon according to the present invention are the precipitation rod and the carbonization rod according to the reaction furnace for the production of polycrystalline silicon according to the present invention. Same as silicon rod.

  In the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, one or two or more of the deposition rods having a heater built therein are used, and the deposition rod is heated. Also good. At that time, all of the precipitation rods installed in the reaction furnace may be heated, or a part thereof may be heated. Further, the heating start time of the precipitation rod may be before the polycrystalline silicon starts to be deposited on the precipitation rod, that is, before the supply of silicon tetrachloride vapor and zinc vapor, or It may be after some amount of polycrystalline silicon is deposited.

  In the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, silicon tetrachloride vapor and zinc vapor are moved downward, and the reaction between silicon tetrachloride and zinc is carried out in the insertion vessel. The polycrystalline silicon is deposited on the deposition rod by causing the deposition rod to exist along the flow of silicon tetrachloride vapor and zinc vapor while producing polycrystalline silicon.

  When the polycrystalline silicon production method using the reactor for producing polycrystalline silicon according to the present invention is completed, the supply of silicon tetrachloride vapor and zinc vapor is stopped, the reactor is cooled, and then the inner tube for the discharge pipe is removed. After that, the insertion vessel in which polycrystalline silicon is deposited inside and the deposition rod in which polycrystalline silicon is deposited on the surface are taken out of the reactor. Then, the polycrystalline silicon deposited in the insertion container is scraped off, and the polycrystalline silicon deposited on the deposition rod is scraped off from the deposition rod to obtain polycrystalline silicon. For example, in the embodiment shown in FIG. 7, after removing the attached members such as the inner pipe 14 for the discharge pipe and the supply pipe 7 for the silicon tetrachloride vapor and the supply pipe 8 for the zinc vapor, the upper side of the reaction furnace 30a Open the lid 2 a, take out the silicon carbide rod 3 from the upper side of the side wall 1, open the lid 2 b below the reaction furnace 30 a, and insert the insertion container from the lower side of the side wall 1. 13 is taken out. Alternatively, when the silicon carbide rod 3 is fixed to the lid portion 18 of the insertion container and is not fixed to the fixing member 4 of the nitrogen gas pipe, the exhaust pipe insertion pipe 14 and the tetrachloride After removing the attached members such as the silicon vapor supply pipe 7 and the zinc vapor supply pipe 8, the lid 2 b on the lower side of the reaction furnace 30 a is opened, and the silicon carbide is introduced from the lower side of the side wall 1. The insertion container 13 is taken out together with the rod 3 and the lid 18 of the insertion container. Further, in the embodiment of FIG. 9, after removing the attached members such as the inner pipe 14 for the discharge pipe and the supply pipe 7 for the silicon tetrachloride vapor and the supply pipe 8 for the zinc vapor, the lower side of the reactor 30b The lid portion 2b is opened, and the insertion container 13 to which the silicon carbide rod 3 is fixed is taken out from the lower side of the side wall portion 1. Further, in the embodiment shown in FIG. 10, after the auxiliary members such as the discharge pipe inner tube 14 and the silicon tetrachloride vapor supply pipe 7 and the zinc vapor supply pipe 8 are removed, the lower side of the reactor 30c is removed. The lid 2b is opened, and the insertion container 13 is taken out from the lower side of the side wall 1 together with the silicon carbide rod 3 and the lid 18 of the insertion container.

  Of the precipitation rods, the silicon carbide rods after scraping the polycrystalline silicon are again used in the method for producing polycrystalline silicon of the present invention. Further, before reuse, the silicon carbide rod may be washed with pure water or an acid such as hydrochloric acid, nitric acid, hydrofluoric acid or the like.

Thus, the polycrystalline silicon obtained by the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention contains zinc because it is produced using zinc as a reducing agent. The zinc content in the polycrystalline silicon obtained by the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon of the present invention is 0.1 to 100 ppm by mass, preferably 0.1 to 10 ppm by mass, Most preferably, it is 0.1-1 mass ppm. 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 polycrystalline silicon obtained by the polycrystalline silicon production method using the reactor for producing polycrystalline silicon according to the present invention is a dendritic shape, a needle shape or a plate shape, and a diameter of 3 μm or less. It is not granular. In the method for producing polycrystalline silicon using the reactor for producing polycrystalline silicon according to the present invention, silicon crystals grow in dendrites or needles, so that they grow into large dendrites or needles. In addition to large dendritic or needle-like materials, polycrystalline silicon includes plate-like or small dendritic or needle-like materials. In some cases, the dendritic or needle-like materials are crushed when scraped off from the silicon rod, resulting in small dendritic or needle-like shapes. 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 (11-1) of FIG. 11, and the needle shape is the shape of FIG. As shown in (11-2), it is a shape that extends in a substantially straight line, and the plate shape is a shape that extends 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. Further, 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 (11-1) of FIG. 11). In the case of a needle shape, it indicates the length of the crystal (the length of 33b in (11-2) of FIG. 11), and in the case of a plate shape, it indicates the longest diameter of the crystal.

  FIG. 12 is a schematic end view of a comparative reactor in which an intubation tube is simply installed in the discharge tube. As shown in FIG. 12, an intubation tube 37 is installed in the discharge tube 38. If no insertion vessel is installed in the reactor, the exhaust gas indicated by the arrow is not only inside the inner tube 37 but also between the exhaust tube 38 and the inner tube 37. 35 flows into the gas 35, so that silicon is deposited inside the discharge pipe 38. In such a comparative example, if the gap is completely eliminated so that the exhaust gas does not flow into the gap between the exhaust pipe 38 and the internal intubation 37, the internal intubation 37 is inserted into the exhaust pipe 38. When the discharge pipe 38 or the inner intubation 37 is easily damaged, or when the exhaust pipe 38 and the inner intubation 37 are expanded by heat during reaction, The discharge pipe 38 or the internal intubation 37 is damaged.

  FIG. 13 is a schematic end view of a comparative reactor in which an intubation tube is not connected to the insertion vessel, but as shown in FIG. 13, an intubation tube 37 is installed in the discharge tube 38, When the insertion vessel 39 is installed in the reaction furnace, but the insertion tube 37 is not connected to the discharge port of the insertion vessel 39, the exhaust gas indicated by the arrow is discharged from the insertion vessel 39 and the side wall of the reaction furnace. 40 and the clearance 41 between the discharge pipe 38 and the inner intubation 37.

  FIG. 14 is a schematic end view of a reaction furnace of a comparative example in which the intubation tube enters the inside of the discharge port of the insertion vessel, although the intubation tube is connected to the insertion vessel, as shown in FIG. In addition, when the intubation tube 37 enters the inside of the discharge port of the insertion container 39, the direction in which the exhaust gas indicated by the arrow flows from the inside of the insertion container 39 toward the inner tube 37, and the insertion Since the direction when flowing through the gap between the container 39 and the inner intubation 37 and into the gap 36 between the discharge pipe 38 and the inner intubation 37 is the same direction, the structure shown in FIG. The exhaust gas easily flows from the inner container 39 side to the gap 36 side through the gap between the container 39 and the inner tube 37. In this case, even if an inert gas is supplied to the gap 36 to pressurize the gap 36 side, it passes through the gap between the insertion container 39 and the inner insertion tube 37, and from the insertion container 39 side. The exhaust gas cannot be prevented from flowing into the gap 36 side.

  In the case of the embodiment in which the silicon carbide rod is installed in the insertion container, since silicon carbide is a hard material, when the polycrystalline silicon is scraped off from the silicon carbide rod after the completion of the manufacturing process, The silicon carbide rod does not break. Therefore, the silicon carbide rod can be reused. In addition, since silicon carbide has an expansion coefficient close to that of silicon, the silicon carbide rod is unlikely to be broken due to a difference in shrinkage when cooled after the reaction is completed. In addition, the presence of the silicon carbide rod promotes the precipitation to the silicon carbide rod, so the yield of polycrystalline silicon is increased, and the silicon is deposited in the insertion vessel where it is difficult to take out the polycrystalline silicon. Therefore, a large amount of the polycrystalline silicon is deposited on the silicon carbide rod which is easy to separate, so that the recovery time of the deposited polycrystalline silicon is shortened and the production efficiency is increased. Further, since silicon carbide is a black or dark green material, it easily absorbs radiant heat in the reaction furnace, and the yield of polycrystalline silicon 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
In the following reactor, zinc vapor heated and vaporized from a zinc vapor supply pipe to 930 ° C. was introduced into the reaction furnace together with nitrogen gas, and vaporized by heating to 930 ° C. from a silicon tetrachloride vapor supply pipe. While supplying silicon tetrachloride vapor into the interior vessel installed in the reactor, the reactor is set to 930 ° C., the heating temperature of the silicon carbide rod is set to 1,000 ° C., and silicon tetrachloride is introduced at a rate of 74 g / min. Then, zinc was supplied at a rate of 50 g / min to react silicon tetrachloride with zinc.
<Reactor (form example of FIG. 1)>
Reaction furnace: Uses a quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm. Inner vessel: Uses an insertion vessel with an inner diameter of 260 mm x length of 1,700 mm and a lid, silicon carbide silicon tetrachloride vapor Positional relationship in the vertical direction between the supply pipe and the zinc vapor supply pipe: the same height Horizontal positional relationship between the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe: Positional relationship shown in FIG. 4 Discharge pipe inner diameter at the reactor outlet: 130 mm
Position of the discharge pipe: The lower side of the discharge pipe 6 is 700 mm above the upper surface of the lid 2b on the lower side of the reactor. Inner tube for discharge pipe: material is quartz, inner diameter 102mm, outer diameter 109mm
Leakage prevention wall for exhaust gas: inner diameter 90mm, outer diameter 95mm
Length of the exhaust gas leakage prevention wall entering the inside of the exhaust pipe intubation: 2 mm before reaction, 2.6 mm during reaction
Gap between the inner pipe for the exhaust pipe and the leakage prevention wall of the exhaust gas: 3.5 mm before reaction, 3.3 mm at the time of reaction
Gap between the tube end of the inner tube for the discharge tube and the outer wall of the container: 5 mm before reaction, 4.5 mm during reaction
Supply amount of nitrogen gas: 10 NL / min

And after reacting for 40 hours, it cooled. Next, the internal pipe for the discharge pipe and the attachment members such as the supply pipe for silicon tetrachloride vapor and the supply pipe for zinc vapor are removed, the insertion vessel is taken out of the reactor, and the insertion vessel for the next batch is installed. The next batch was prepared. At this time, the time from the start of the operation of taking out the insertion container until the preparation of the next batch was completed was approximately 1 hour. Moreover, when the insertion vessel was taken out and the side wall of the reaction furnace was visually observed, no silicon deposition was observed. Also, no silicon deposition was observed inside the discharge pipe.
Further, it was confirmed that acicular polycrystalline silicon was deposited in the taken-out insertion container. Next, polycrystalline silicon was scraped from the insertion container to obtain polycrystalline silicon. The yield of polycrystalline silicon was 64% based on the feedstock, and the purity of polycrystalline silicon was 6-N.

(Example 2)
It carried out similarly to Example 1 except using the following reactor. That is, it carried out similarly to Example 1 except installing a silicon carbide stick | rod in an insertion container.
<Reactor (in the embodiment shown in FIG. 7, the number of silicon carbide rods installed is 3)>
Reaction furnace: Uses a quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm. Inner vessel: Uses an insertion vessel with an inner diameter of 260 mm x length of 1,700 mm and a lid, silicon carbide silicon tetrachloride vapor Positional relationship in the vertical direction between the supply pipe and the zinc vapor supply pipe: the same height Horizontal positional relationship between the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe: Positional relationship shown in FIG. 4 Discharge pipe inner diameter at the reactor outlet: 130 mm
Position of the discharge pipe: The lower side of the discharge pipe 6 is 700 mm above the upper surface of the lid 2b on the lower side of the reactor. Inner tube for discharge pipe: material is quartz, inner diameter 102mm, outer diameter 109mm
Leakage prevention wall for exhaust gas: inner diameter 90mm, outer diameter 95mm
Length of the exhaust gas leakage prevention wall entering the inside of the exhaust pipe intubation: 2 mm before reaction, 2.6 mm during reaction
Gap between the inner pipe for the exhaust pipe and the leakage prevention wall of the exhaust gas: 3.5 mm before reaction, 3.3 mm at the time of reaction
Gap between the tube end of the inner tube for the discharge tube and the outer wall of the container: 5 mm before reaction, 4.5 mm during reaction
Mass ratio of silicon carbide rod: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon is 85:15, outer diameter 30 mm × length 1,000 mm, number of three (on an arc centered on the center of the reactor, etc. Installed at intervals)
Supply amount of nitrogen gas: 10 NL / min

And after reacting for 40 hours, it cooled. Next, the internal members for the discharge pipe, the supply pipe for silicon tetrachloride vapor, the supply pipe for zinc vapor and the like are removed, the silicon carbide rod and the insertion vessel are taken out of the reactor, and the silicon carbide rod for the next batch And the insertion container was installed and the next batch was prepared. At this time, the time from the start of the operation of taking out the silicon carbide rod and the insertion container to the completion of preparation for the next batch was about 1 hour. Moreover, when the insertion vessel was taken out and the side wall of the reaction furnace was visually observed, no silicon deposition was observed. Also, no silicon deposition was observed inside the discharge pipe.
Further, it was confirmed that acicular polycrystalline silicon was deposited on the surface of the silicon carbide rod taken out and in the insertion container. Next, the polycrystalline silicon was scraped off from the silicon carbide rod, and the polycrystalline silicon was scraped out from the insertion container to obtain polycrystalline silicon. The yield of polycrystalline silicon was 64% based on the feedstock, and the purity of polycrystalline silicon was 6-N. The silicon carbide rod was not broken when the polycrystalline silicon was scraped off, and was in a reusable state.

(Comparative Example 1)
It carried out similarly to Example 1 except not installing both an internal container and the intubation pipe for discharge pipes.
And after reacting for 48 hours, it cooled. After cooling, silicon deposited in the reaction furnace was taken out of the reaction furnace, and the next batch was prepared. At this time, the time from the start of the silicon removal operation to the completion of preparation for the next batch was approximately 5 hours. In the reaction furnace, silicon was deposited on the furnace wall. Further, silicon was deposited in the discharge pipe.

  According to the present invention, since polycrystalline silicon hardly deposits on the inside of the reactor wall and the exhaust gas discharge pipe, the polycrystalline silicon can be efficiently manufactured.

DESCRIPTION OF SYMBOLS 1 Side wall 2, 2a, 2b of reactor Furnace part 3 Silicon carbide rod 4 Fixing member of nitrogen gas pipe 5 Heater 6 Exhaust pipe 7 Silicon tetrachloride vapor supply pipe 8 Zinc vapor supply pipe 9 Silicon tetrachloride vapor 10 Zinc vapor DESCRIPTION OF SYMBOLS 11 Exhaust gas 12 Furnace inner-wall collar part 13 Inner container 14 Inner tube 15 for exhaust pipes Leakage prevention wall 16 of exhaust gas 16 Nitrogen gas 17 Outlet 18 Lid part 20, 30a, 30b, 30c of insertion container Reactor 31 Trunk part 32 Branch Part 35 Clearance between discharge pipe and internal intubation 36 Clearance between side wall of reaction furnace and internal container 37 Internal intubation 38 Discharge pipe 39 Internal container 40 Side wall of reaction furnace 41 Clearance 141 between exhaust pipe and internal intubation End 142 of gas leakage prevention wall Pipe end 143 of exhaust pipe intubation tube Opening 151 of exhaust gas leakage prevention wall 15 on the outlet side of exhaust gas Nitrogen gas supply pipe 161 Inner tube for exhaust pipe and leakage prevention wall of exhaust gas With The gap between the gap 165 intubation for the discharge pipe and discharge pipe between the gap 163 in 挿容 instrument and a side wall portion of the furnace between the gap 162 in 挿容 instrument with the tube end of the intubation for the discharge pipe

Claims (5)

A reactor for reacting silicon tetrachloride with zinc to produce polycrystalline silicon,
An insertion vessel is installed in the reaction furnace, and an exhaust gas discharge port is formed in the lower part of the insertion vessel. An exhaust gas surrounding the discharge port is formed on the outer wall of the insertion vessel. Leakage prevention wall is formed,
A silicon tetrachloride vapor supply pipe for supplying silicon tetrachloride vapor into the insertion vessel and a zinc vapor supply tube for supplying zinc vapor into the insertion vessel are provided at the top of the reactor. And
At the bottom of the reactor, has a discharge pipe for discharging exhaust gas,
The reaction furnace has an inert gas supply pipe for supplying an inert gas in the reaction furnace,
In the discharge pipe, an intubation for the discharge pipe is installed,
The exhaust gas leakage prevention wall enters the inside of the exhaust pipe intubation, and between the exhaust pipe intubation and the exhaust gas leakage prevention wall, and the pipe end of the exhaust pipe intubation and the pipe A gap is formed between the insertion container and
A reactor for producing polycrystalline silicon.   The reaction furnace for producing polycrystalline silicon according to claim 1, wherein a precipitation rod is installed in the insertion vessel.   3. The reactor for producing polycrystalline silicon according to claim 2, wherein the precipitation rod is a silicon carbide rod.   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 4. A reactor for producing polycrystalline silicon according to Item 3.   5. The reactor for producing polycrystalline silicon according to claim 1, wherein a heat insulating material is disposed between the discharge pipe and the internal pipe for the discharge pipe.