JP2013071882A - Method for manufacturing polycrystalline silicon and device for manufacturing polycrystalline silicon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing polycrystalline silicon in which polycrystalline silicon deposited within a reactor can be easily removed from the reactor, and that has high manufacturing efficiency.SOLUTION: The method includes: a first step of reacting silicon tetrachloride and zinc within a reactor to form polycrystalline silicon within the reactor; a second step of feeding only silicon tetrachloride, or feeding silicon tetrachloride and zinc in an amount in which the molar ratio of zinc to silicon tetrachloride is smaller than the molar ratio at the first step, into the reactor at 907°C to 1,200°C; and a third step of creating an inert gas atmosphere within the reactor at a temperature within the reactor of 800°C or higher, and subsequently moving the polycrystalline silicon from within the reactor at 800°C or higher to a cooling space having an inert gas atmosphere that is connected to the reactor, thereby removing the polycrystalline silicon from inside of the reactor to the outside of the reactor, and cooling the polycrystalline silicon.

Description

  The present invention relates to a method for manufacturing polycrystalline silicon and a polycrystalline silicon manufacturing apparatus used therefor, and more particularly to a method for manufacturing polycrystalline silicon for solar cells and a polycrystalline silicon manufacturing apparatus used therefor. It is.

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 polycrystalline silicon for recovering 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 polycrystalline silicon, characterized in that it is used as a base agent, and the recovered chlorine is synthesized with hydrogen to form hydrogen chloride, which is used for chlorination treatment of metallic silicon to produce silicon tetrachloride (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, it is preferable that the obtained silicon has 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 polycrystalline silicon 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 (precipitation rod) above the reaction temperature, needles and flakes are formed on the core rod rather than the reactor. The silicon is 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 case of a polycrystalline silicon manufacturing method in which needle-like or flaky silicon is crystallized in a reaction furnace as in Patent Document 5, since polycrystalline silicon adheres to the inner wall and precipitation rod of the reaction furnace, tetrachloride is used. After the reaction between silicon and zinc is completed, the reactor is once cooled, then the silicon adhering to the inner wall of the reactor is scraped, and the polycrystalline silicon deposited on the precipitation rod is removed from the reaction furnace together with the precipitation rod. Thus, after the polycrystalline silicon produced in the reaction furnace was taken out of the reaction furnace, the temperature in the reaction furnace was raised to restart the reaction between silicon tetrachloride and zinc.

  However, in such a manufacturing method, it takes a long time to cool and raise the temperature of the reaction furnace, and it takes time to peel off the polycrystalline silicon adhering to the inner wall of the reaction furnace. Therefore, the conventional polycrystalline silicon manufacturing method has a problem that the manufacturing efficiency of the polycrystalline silicon is deteriorated.

  Therefore, an object of the present invention is to provide a method for producing polycrystalline silicon, in which polycrystalline silicon deposited in the reaction furnace can be easily taken out from the reaction furnace and the production efficiency is high.

  As a result of intensive studies to solve the above-described problems in the prior art, the present inventors have performed (1) a step of generating polycrystalline silicon by reacting silicon tetrachloride with zinc in a reaction furnace. After that, by supplying silicon tetrachloride and zinc into the reactor only by silicon tetrachloride or at a molar ratio smaller than the molar ratio of zinc to silicon tetrachloride in the production process of polycrystalline silicon, The polycrystalline silicon adhering to the inner wall and the precipitation rod of the reactor can be easily peeled off from the inner wall and the precipitation rod of the reaction furnace. Therefore, (2) the reaction is carried out from the reaction furnace while keeping the temperature in the reaction furnace high. The inventors have found that polycrystalline silicon can be taken out of the furnace, and have completed the present invention.

That is, the present invention (1) includes a first step in which silicon tetrachloride and zinc are reacted in a reaction furnace to produce polycrystalline silicon in the reaction furnace,
At 907-1200 ° C., only silicon tetrachloride is supplied into the reactor, or the molar ratio of zinc to silicon tetrachloride is less than the molar ratio in the first step. A second step of supplying silicon and zinc;
The temperature in the reaction furnace is 800 ° C. or higher, the reaction furnace is made an inert gas atmosphere, and then the polycrystalline silicon is cooled from the reaction furnace at 800 ° C. or higher to the inert gas atmosphere cooling space connected to the reaction furnace. A third step of taking polycrystalline silicon out of the reactor from the reactor and cooling it, by moving to
The present invention provides a method for producing polycrystalline silicon characterized by comprising:

Further, the present invention (2) has a silicon tetrachloride vapor supply pipe and a zinc vapor supply pipe in the upper part and an exhaust gas discharge pipe in the lower part, and silicon tetrachloride and zinc are mixed in the reactor. A reaction furnace for generating polycrystalline silicon by reacting, and a cooling unit installed on the bottom side of the reaction furnace to form a cooling space of an inert gas atmosphere,
Between the reactor and the cooling section, when silicon tetrachloride and zinc are reacted in the reactor, the reactor is closed so that the gas in the reactor does not leak into the cooling section, and After the reaction between silicon tetrachloride and zinc, the structure is opened so that the polycrystalline silicon can move from the reaction furnace to the cooling space.
An apparatus for producing polycrystalline silicon characterized by the above is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the taking-out from the reaction furnace of the polycrystalline silicon which precipitated in the reaction furnace is easy, and the manufacturing method of polycrystalline silicon with high manufacturing efficiency can be provided.

It is a typical end view of the example of the form of the polycrystalline silicon manufacturing apparatus used with the manufacturing method of the polycrystalline silicon of the present invention. It is an end elevation which shows the side wall part of the reactor in FIG. 1, a silicon carbide rod, the partition wall of the supply space of silicon tetrachloride vapor, and the partition wall of the supply space of zinc vapor. It is a typical end view which shows a mode that the polycrystalline silicon produced | generated within the reaction furnace is taken out of the reaction furnace. It is a typical end view which shows a mode that the polycrystalline silicon produced | generated within the reaction furnace is taken out of the reaction furnace. It is a typical end view which shows a mode that the polycrystalline silicon produced | generated within the reaction furnace is taken out of the reaction furnace. It is a typical end view which shows arrangement | positioning of the side wall part of a reaction furnace, and a silicon carbide rod. It is a schematic diagram which shows the example (B) of a silicon tetrachloride vapor | steam supply means and a zinc vapor | steam supply means. It is a schematic diagram which shows the example (C) of a silicon tetrachloride vapor | steam supply means and a zinc vapor | steam supply means. It is a typical end view of the example of the form of the reactor used for the manufacturing method of the polycrystalline silicon of the present invention. It is an end elevation which shows the side wall part of the reaction furnace in FIG. 9, the silicon carbide rod, the partition wall of the supply space of silicon tetrachloride vapor, and the partition wall of the supply space of zinc vapor.

  The manufacturing method of the polycrystalline silicon of this invention is demonstrated with reference to FIGS. FIG. 1 is a schematic end view of an embodiment of a polycrystalline silicon production apparatus used in the polycrystalline silicon production method of the present invention. FIG. 2 is an end view showing the side wall (reactor) of the reactor in FIG. 1, the silicon carbide rod, the partition wall of the silicon tetrachloride vapor supply space, and the partition wall of the zinc vapor supply space, x It is an end elevation when cut in the horizontal direction by -x line. 3 to 5 are schematic end views showing how the polycrystalline silicon generated in the reaction furnace is taken out of the reaction furnace. In FIG. 2, descriptions other than those illustrated are omitted for convenience of explanation. Moreover, although the example of the form in the case of using a silicon carbide rod as a precipitation rod was described as a typical example in FIGS. 1-5, in this invention, a precipitation rod is not limited to a silicon carbide rod.

  In FIG. 1, a polycrystalline silicon manufacturing apparatus 50 includes a reaction furnace 20 and a cooling unit 44 installed on the bottom side thereof. In FIG. 1, the reaction furnace 20 includes a side wall part 31 having a vertically long cylindrical shape, a lid part 32 that covers the side wall part 31, 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 pipe 6 for discharging the exhaust gas 11 is provided to the lower part of the reaction furnace 20. Is attached. In the reaction furnace 20, four silicon carbide rods (precipitation rods) 3 are installed via the fixing member 4. The fixing member 4 includes a silicon tetrachloride vapor supply space partition member 13 for partitioning a silicon tetrachloride vapor supply space, and a zinc steam supply space partition for partitioning a zinc vapor supply space. The member 14 is fixed. The silicon tetrachloride vapor supply pipe 7 is connected to the partition member 13 in the silicon tetrachloride vapor supply space, and the zinc vapor supply pipe 8 is connected to the partition member 14 in the zinc vapor supply space. The fixing member 4 is hooked on the furnace inner wall collar 12 formed on the inner wall of the side wall 31, so that the silicon carbide rod 3 is installed so as to protrude downward into the reaction furnace 20. In addition, a partition member 13 in the supply space for silicon tetrachloride vapor and a partition member 14 in the supply space for zinc vapor are installed in the upper part of the reaction furnace 20. In addition, the side wall part 31 and the cover part 32 are sealed, for example by pinching | sealing a sealing material between each collar part and bolting collar parts.

  One end of the silicon tetrachloride vapor supply pipe 7 is connected to the partition member 13 of the silicon tetrachloride vapor supply space, and the other end is connected to the silicon tetrachloride evaporator. One end of the zinc vapor supply pipe 8 is connected to the partition member 14 in the zinc vapor supply space, and the other end is connected to a zinc evaporator. The exhaust pipe 6 is connected to a recovery device for recovering exhaust gas 11, that is, zinc chloride gas generated when silicon tetrachloride reacts with zinc and unreacted silicon tetrachloride vapor and zinc vapor. ing.

  As shown in FIGS. 1 and 2, the partition member 13 in the silicon tetrachloride vapor supply space includes a cylindrical partition wall 131 and a circular upper member. The partition member 14 in the zinc vapor supply space includes a cylindrical inner partition wall 141, a cylindrical outer partition wall 142, and a donut-shaped upper member. The partition wall 131, the partition wall 141, and the partition wall 142 are installed concentrically with the center of the reactor.

  The reaction furnace 20 is installed on the surface plate 41 by fixing the fixing portion 39 at the lower end of the side wall portion 31 to the surface plate 41. The surface plate 41 is a base on which the reaction furnace 20 is installed. The space between the surface plate 41 and the fixed portion 39 at the lower end of the side wall is sealed so that outside air does not enter the space 2 in the reaction furnace.

  A cooling unit 44 that forms a cooling space 45 is provided below the surface plate 41, that is, on the bottom side of the reaction furnace 20. The surface plate 41 and the cooling unit 44 are sealed so that outside air does not enter the cooling space 45.

  In the cooling space 45, a silicon receiving portion 43 in the cooling space for receiving polycrystalline silicon moving from the reaction furnace 20 is installed.

  At the boundary between the space 2 in the reaction furnace and the cooling space 45, an opening / closing part 42 for separating the space 2 in the reaction furnace and the cooling space 45 is installed so as to be openable and closable. When the reaction between the silicon tetrachloride and zinc is performed in the reaction furnace 20, the open / close section 42 includes a space 2 and a cooling space 45 in the reaction furnace so that the gas in the reaction furnace does not leak into the cooling section 44. After the reaction between silicon tetrachloride and zinc is finished, the polycrystalline silicon produced in the reaction furnace 20 is moved into the cooling space 45 from the reaction furnace 20 to move to the cooling space 45. This is a member that opens to connect the space 2 and the cooling space 45. In addition, the open / close portion 42 is provided with an in-reactor silicon receiving portion 46 and a heat insulating material 47.

  The cooling unit 44 includes an inert gas supply pipe (not shown) for supplying an inert gas into the cooling unit 44 and an inert gas in the cooling unit 44 in order to make the cooling space 45 an inert gas atmosphere. An inert gas discharge pipe (not shown) for discharging the active gas is attached.

  Means for shielding heat between the reaction furnace 20 and the cooling space 45 may be provided so that the heat of the reaction furnace 20 is not transmitted to the cooling space 45. As a means for shielding heat between the reaction furnace 20 and the cooling space 45, for example, installing a heat insulating material 47 in the opening / closing part 42 provided at the boundary between the reaction furnace 20 and the cooling space 45, and attaching the reaction furnace 20 For example, in the embodiment shown in FIG. 1, a heat insulating material is provided between the surface plate 41 and the surface plate 41, and a heat insulating material layer is disposed inside the surface plate 41. .

  The polycrystalline silicon manufacturing method of the present invention using the polycrystalline silicon manufacturing apparatus shown in FIG. 1 will be described with reference to FIGS. In the method for producing polycrystalline silicon according to the present invention, first, in the reaction furnace 20 shown in FIG. 1, a step of producing polycrystalline silicon by reacting silicon tetrachloride with zinc is performed. First, the inside of the reaction furnace 20 is heated by the heater 5, and then silicon tetrachloride and zinc are vaporized by the respective evaporators, and the silicon tetrachloride vapor 9 is supplied from the silicon tetrachloride vapor supply pipe 7 to the zinc vapor. While supplying 10 from the zinc vapor supply pipe 8 into the reaction furnace 20, the exhaust gas 11 is discharged from the discharge pipe 6 to the outside of the reaction furnace 20. At this time, silicon tetrachloride reacts with zinc in the reaction furnace 20 to generate silicon, but since the silicon carbide rod (precipitation rod) 3 is installed in the reaction furnace 20, FIG. As shown, the generated silicon (polycrystalline silicon 1) is deposited on a silicon carbide rod (precipitation 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 zinc vapor are discharged from the upper part of the reaction furnace 20. Since the silicon carbide rod (precipitation rod) 3 is present along the flow, the silicon crystal grows so as to cover the silicon carbide rod (precipitation rod) 3. Moreover, although zinc chloride is also produced | generated by reaction of silicon tetrachloride and zinc, zinc chloride gas is discharged | emitted from the exhaust pipe 6 as exhaust gas 11 with the unreacted silicon tetrachloride vapor | steam and zinc vapor | steam outside.

  Since the silicon tetrachloride vapor 9 is first supplied to the partition member 13 in the silicon tetrachloride vapor supply space, it diffuses into the silicon tetrachloride vapor supply space 132 partitioned by the partition member 13. The silicon tetrachloride vapor 9 is supplied to the reactor 20 through the silicon tetrachloride vapor supply port 133 after being diffused into the silicon tetrachloride vapor supply space 132. Further, since the zinc vapor 10 is first supplied to the partition member 14 in the zinc vapor supply space, it diffuses into the zinc vapor supply space 143 partitioned by the partition member 14. The zinc vapor 10 is supplied into the reaction furnace 20 from the zinc vapor supply port 144 after being diffused into the zinc vapor supply space 143. In the reactor 20, the silicon tetrachloride vapor supply port 131 has a circular shape, and the zinc vapor supply port 144 has a donut shape.

  The polycrystalline silicon 1 is deposited on the silicon carbide rod (precipitation rod) 3 by performing the reaction between silicon tetrachloride and zinc in the reaction furnace 20 for a predetermined time.

  Next, only the silicon tetrachloride vapor 9 is supplied into the reaction furnace 20 at a temperature of 907 to 1200 ° C. in the reaction furnace 20, or the molar ratio of zinc to silicon tetrachloride is higher than the molar ratio in the first step. A step of supplying silicon tetrachloride vapor 9 and zinc vapor 10 is performed so as to be small.

  Then, the silicon tetrachloride vapor 9 and the zinc vapor are placed in the reactor 20 for a predetermined time so that only the silicon tetrachloride vapor 9 or the molar ratio of zinc to silicon tetrachloride is smaller than the molar ratio in the first step. By supplying 10, as shown in FIG. 4, the polycrystalline silicon 1 is separated from the silicon carbide rod (precipitation rod) 3 and falls to the in-reactor silicon receiving portion 46 at the bottom of the reaction furnace 20.

  Next, the step of taking out the polycrystalline silicon 1 that has dropped to the in-reactor silicon receiving portion 46 at the bottom of the reaction furnace 20 from the inside of the reaction furnace 20 to the outside of the reaction furnace 20 is performed. First, when the temperature in the reaction furnace is 800 ° C. or higher, the supply of silicon tetrachloride vapor 9 and zinc vapor 10 into the reaction furnace 20 is stopped. Next, the temperature in the reaction furnace is 800 ° C. or higher, and an inert gas is supplied from an inert gas supply pipe (not shown) into the reaction furnace 20 and discharged from the discharge pipe 6. Inside is an inert gas atmosphere. In parallel, an inert gas is supplied from an inert gas supply pipe (not shown) into the cooling unit 44 and discharged from an inert gas discharge pipe (not shown) to form a cooling space. 45 is an inert gas atmosphere. Next, as shown in FIG. 5, by opening the opening / closing part 42, the polycrystalline silicon 1 located at the bottom of the reaction furnace 20 is dropped into the silicon receiving part 43 in the cooling space, so that the polycrystalline silicon 1 is 800 It moves from the inside of the reaction furnace 20 at a temperature of 0 ° C. or more to the cooling space 45. Thus, the polycrystalline silicon 1 is taken out from the reaction furnace 20 to the outside of the reaction furnace 20. 3 to 5, for convenience of drawing, the polycrystalline silicon 1 is described as a lump, but in actuality, at least one of rod-like, granular or plate-like, or rod-like, granular and plate-like ones is used. Is a shape in which a plurality of are joined.

  Next, the opening / closing part 42 is closed to return to the state shown in FIG. 1, and the supply of the silicon tetrachloride vapor 9 and the zinc vapor 10 is started again to produce polycrystalline silicon in the reaction furnace 20.

That is, in the method for producing polycrystalline silicon according to the present invention, the first step of producing polycrystalline silicon in the reaction furnace by reacting silicon tetrachloride and zinc in the reaction furnace,
At 907-1200 ° C., only silicon tetrachloride is supplied into the reactor, or the molar ratio of zinc to silicon tetrachloride is less than the molar ratio in the first step. A second step of supplying silicon and zinc;
The temperature in the reaction furnace is 800 ° C. or higher, the reaction furnace is made an inert gas atmosphere, and then the polycrystalline silicon is cooled from the reaction furnace at 800 ° C. or higher to the inert gas atmosphere cooling space connected to the reaction furnace. A third step of taking polycrystalline silicon out of the reactor from the reactor and cooling it, by moving to
It is a manufacturing method of the polycrystalline silicon characterized by having.

  The first step according to the method for producing polycrystalline silicon of the present invention is a step of reacting silicon tetrachloride and zinc in a reaction furnace to produce polycrystalline silicon in the reaction furnace.

  In the first step, the method for producing polycrystalline silicon by reacting silicon tetrachloride with zinc is not particularly limited, and the method for producing crystals of polycrystalline silicon by reacting silicon tetrachloride with zinc in a reaction furnace. If it is. In the first step, silicon tetrachloride and zinc are reacted to produce polycrystalline silicon. Silicon tetrachloride vapor and zinc vapor are supplied from the top of the vertical reactor, and the vertical reactor is A method of generating polycrystalline silicon in the reaction furnace by contacting the silicon tetrachloride vapor and the zinc vapor in the reaction furnace by discharging exhaust gas from the bottom (hereinafter referred to as the first step form) A)) is preferable in that the yield of polycrystalline silicon is high and the polycrystalline silicon can be easily taken out of the reactor. Note that the vertical reactor is such that silicon tetrachloride vapor and zinc vapor supplied into the reactor from the top of the reactor react while moving downward from the top of the reactor toward the bottom. Refers to the reactor. In other words, the vertical reactor is a reactor in which raw materials and exhaust gas flow from the upper part to the lower part of the reactor.

  In the method for producing polycrystalline silicon according to the present invention, the temperature in the reactor is about 1,000 ° C., and the reactor is made of quartz such as transparent quartz, opaque quartz, sintered quartz, silicon carbide, nitriding Silicon and the like are mentioned. From the viewpoint of strength, 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. Further, depending on the structure of the reaction furnace, the material of the reaction furnace is not particularly limited as long as it can withstand the heating temperature during the reaction. Further, the side wall portion and the lid portion of the reaction furnace may be made of different materials.

  The size of the reaction furnace is not particularly limited, but is appropriately selected depending on the supply conditions of silicon tetrachloride and zinc. In the case of the vertical reaction furnace according to the first step A, preferably, the vertical length of the reaction furnace is 1,000 to 6,000 mm, and in the case of a cylindrical shape, the diameter is 200 to 2, 000 mm.

  The reaction furnace is provided with means for supplying silicon tetrachloride and zinc. In the vertical reactor according to Form A of the first step, the silicon tetrachloride vapor supply means and the zinc vapor supply means are attached to the upper part of the reaction furnace, and the discharge pipe is attached to the lower part of the reaction furnace. And in the reactor which concerns on the form A of a 1st process, the downward flow of raw material vapor | steam is formed in a reactor, and the position which can raise | generate reaction of silicon tetrachloride and zinc in a reactor ( At a position in the vertical direction), a silicon tetrachloride vapor supply means, a zinc vapor supply means, and a discharge pipe are attached.

  A heater is installed around the side wall of the reactor. As the heater, an electric heater is preferable.

  In the reaction of silicon tetrachloride vapor and zinc vapor, when silicon tetrachloride vapor and zinc vapor are vigorously stirred in the reaction furnace, fine granular polycrystalline silicon having a diameter of 3 μm or less is produced. Granular polycrystalline silicon has a low packing density and takes time to melt. On the other hand, when the silicon tetrachloride vapor and the zinc vapor are in gentle contact in the reactor, preferably at a linear velocity of 5 cm / second or less, a rod-like, granular or plate-like polycrystalline silicon having a large diameter, or Polycrystalline silicon having a shape in which a plurality of polycrystalline silicon in the form of rods, granules or plates with large diameters adheres is produced, but polycrystalline silicon having such a large size is melted compared to fine polycrystalline silicon. It is easy and the melting time is shortened. Therefore, in the first step, in particular, in the first step, Form A, the conditions are such that the silicon tetrachloride vapor and the zinc vapor are not vigorously stirred in the reaction furnace, that is, fine granular polycrystalline silicon having a diameter of 3 μm or less. It is preferable to supply silicon tetrachloride vapor and zinc vapor to the reactor under conditions that are difficult to produce. That is, in the first step, particularly in the form A of the first step, under the supply conditions of the raw material vapor, it is easy to produce polycrystalline silicon having a shape in which a plurality of rod-like, granular or plate-like polycrystalline silicon having a large diameter adheres. Silicon chloride vapor and zinc vapor are supplied to the reactor. Such supply conditions of the raw material vapor are appropriately selected depending on the size of the reaction furnace, the position or number of the deposition rods installed.

  In the first step, in particular, in the form A of the first step, the supply ratio (molar ratio) of silicon tetrachloride vapor and zinc vapor is silicon tetrachloride vapor: zinc vapor = 0.7: 2-1.3: 2. And 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 1.02 to 1.3, and the dilution rate of zinc vapor is a volume fraction ((zinc vapor + inert gas) / Zinc vapor), preferably from 1.005 to 1.3, particularly preferably from 1.01 to 1.2.

  According to “Chemical Handbook” (edited by the Chemical Society of Japan), the boiling point of zinc is 907 ° C. Therefore, in the first step, the reactor is set so that the temperature in the reactor is 907 ° C. or more, which is the boiling point of zinc. Heat. The temperature in the reaction furnace is 907 to 1,200 ° C, preferably 930 to 1,100 ° C. 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 reaction furnace.

  In the first step, in particular, in Form A of the first step, it is preferable to install a precipitation rod in the reaction furnace. By installing the precipitation rod in the reaction furnace, polycrystalline silicon can be selectively deposited on the precipitation rod, and adhesion of polycrystalline silicon to the wall of the reaction furnace can be reduced. In addition, by installing the precipitation rod, it becomes easy to collect the polycrystalline silicon in the lower part of the reactor in the second step.

  Examples of the precipitation rod include a silicon carbide rod, a silicon nitride rod, a tantalum rod, and a silicon rod. In particular, a silicon carbide rod is preferable as the precipitation rod in terms of strength and less influence on the polycrystalline silicon due to impurities. The precipitation rod is installed in the reaction furnace. The shape of the precipitation rod is preferably a prismatic shape or a cylindrical shape, and particularly preferably a cylindrical shape. When the shape of the precipitation rod is a columnar shape, the diameter of the precipitation rod is preferably 1 to 20 cm, and particularly preferably 2 to 10 cm, from the strength and the processed surface. The length of the precipitation rod existing between the lower side of the fixing member 4 and the upper side of the discharge pipe 6 is 5 with respect to the length in the vertical direction from the lower side of the fixing member 4 to the upper side of the discharge pipe 6. -120% is preferable, 20-100% is especially preferable, and 40-90% is still more preferable.

  Of the precipitation rods, silicon carbide rods are silicon carbide molded bodies, but silicon carbide molded bodies are usually porous bodies 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. The impregnated silicon becomes a seed of polycrystalline silicon crystals produced by the reaction, and carbonized. This is preferable in that the precipitation of polycrystalline silicon on the silicon 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.

  Further, even when a porous silicon carbide rod not impregnated with silicon is installed in a reaction furnace and a reaction between silicon tetrachloride vapor and zinc vapor is performed, in the initial stage of the reaction, silicon carbide In the porous structure near the outside of the 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 holes. It will be in the same state. Therefore, a porous silicon carbide rod not impregnated with silicon may be used. Particularly, when a silicon carbide rod is repeatedly used, a porous silicon carbide rod not impregnated with silicon is not used by repeated use. It will be in the same state as the porous silicon carbide rod impregnated.

  The number of deposition rods is one or two or more. Moreover, the installation position of the precipitation rod is not particularly limited. For example, as shown in FIG. 6, when there are four (A) or three (B) silicon carbide rods (precipitation rods), the silicon carbide rod 3 (precipitation rod) is the center of the side wall (reactor) 31. It is preferable that they are installed at equal intervals on a circle 19 centered at. The number and position of the silicon carbide rods are appropriately selected so that polycrystalline silicon is efficiently precipitated depending on the reaction conditions such as the supply conditions of the raw material vapor, the size of the reaction furnace, and the like.

  In FIG. 1, the silicon carbide rod (precipitation rod) 3 is fixed to the fixing member 4, and the fixing member 4 is hooked on the furnace inner wall collar portion 12 in FIG. Although it has been described that the rod is installed downward from the upper part in the reactor, the present invention is not limited to this.

  Further, in order to set the temperature of the silicon carbide rod (precipitation rod) to be higher than the temperature in the reaction furnace, a heater for heating may be provided inside the silicon carbide rod (precipitation rod). . For example, when the temperature in the reaction furnace (side temperature of the reaction furnace) is 930 ° C., the silicon carbide rod (precipitation rod) is set to 1,000 ° C. Crystalline silicon can be deposited. Also, since silicon carbide is a material that has high thermal conductivity and receives a large amount of radiant heat, in the case of a silicon carbide rod, it receives a lot of radiant heat from the side wall of the reactor, and to some extent without heating the silicon carbide rod. It is possible to selectively deposit polycrystalline silicon on a silicon carbide rod.

  In the first step, an inert gas supply pipe such as nitrogen gas can be attached to the reaction furnace to supply the inert gas into the reaction furnace. By supplying the inert gas into the reaction furnace, it is possible to prevent the outside air from entering the reaction furnace.

  Then, by performing the first step, polycrystalline silicon is generated in the reaction furnace.

  The second step according to the method for producing polycrystalline silicon of the present invention is to supply only silicon tetrachloride vapor at 907 to 1200 ° C. in the reactor in which the polycrystalline silicon is produced, or to supply zinc to silicon tetrachloride. In this step, silicon tetrachloride vapor and zinc vapor are supplied so that the molar ratio is smaller than the molar ratio in the first step.

  In the second step, silicon tetrachloride vapor is supplied into the reactor at a temperature in the reactor of 907 to 1200 ° C., preferably 930 to 1100 ° C., or zinc relative to silicon tetrachloride in the first step is supplied. The molar ratio of zinc to silicon tetrachloride is made smaller than the molar ratio to supply silicon tetrachloride vapor and zinc vapor.

  The molar ratio of zinc to silicon tetrachloride in the second step is preferably 0 to 1.5, particularly preferably 0 to 1, and more preferably 0. When the molar ratio of zinc to silicon tetrachloride in the second step is in the above range, the polycrystalline silicon is easily peeled from the wall surface of the reactor and the precipitation rod.

  In the second step, the time for supplying silicon tetrachloride vapor or silicon tetrachloride vapor and zinc vapor to the reactor is appropriately selected depending on the temperature in the reactor, the amount of polycrystalline silicon produced, etc. Is 10 to 120 minutes, particularly preferably 20 to 60 minutes.

  In the second step, the amount of silicon tetrachloride supplied to the reactor is appropriately selected depending on the size of the reactor, the amount of polycrystalline silicon produced, etc., preferably 0.1 to 50 mol / min, especially Preferably it is 0.3-40 mol / min.

  Then, by performing the second step, the polycrystalline silicon adhering to the wall of the reaction furnace is peeled off from the wall of the reaction furnace, and if a precipitation bar is installed in the reaction furnace, it is deposited on the precipitation bar. The polycrystalline silicon thus peeled off from the precipitation rod. However, it does not require all peeling of polycrystalline silicon, and may be adjusted as appropriate according to the amount of silicon tetrachloride supplied.

  The reason why polycrystalline silicon peels from the reactor wall and precipitation rod by supplying silicon tetrachloride vapor, or silicon tetrachloride vapor and zinc vapor into the reaction furnace in the above temperature range in the second step. It is presumed that the polycrystalline silicon present at the wall of the reactor or the interface with the precipitation rod is gasified and disappears by reacting with silicon tetrachloride.

  In the second step, an inert gas supply pipe such as nitrogen gas can be attached to the reaction furnace to supply the inert gas into the reaction furnace. By supplying the inert gas into the reaction furnace, it is possible to prevent the outside air from entering the reaction furnace.

  In the third step according to the method for producing polycrystalline silicon of the present invention, the temperature in the reactor is 800 ° C. or higher, the inside of the reactor is set to an inert gas atmosphere, In this step, polycrystalline silicon is taken out of the reaction furnace and cooled by moving it from the inside to the cooling space of the inert gas atmosphere connected to the reaction furnace.

  In the third step, first, an inert gas atmosphere such as nitrogen gas, helium gas, and argon gas is supplied into the reaction furnace to make the reaction furnace an inert gas atmosphere. However, it is performed at 800 ° C. or higher, preferably 850 ° C. or higher so that it does not become less than 800 ° C.

  In the third step, in order to form a cooling space of an inert gas atmosphere for cooling the polycrystalline silicon, an inert gas is supplied to the cooling space, and the cooling space is made an inert gas atmosphere. The temperature of the cooling space is preferably 25 to 200 ° C, particularly preferably 25 to 100 ° C. In the method for producing polycrystalline silicon according to the present invention, when the first step and the second step are performed, the gas in the reaction furnace and the gas in the cooling space come and go between the reaction furnace and the cooling space. When the polycrystalline silicon is moved from the reaction furnace to the cooling space in the third step, the cooling space is formed so that the inside of the reaction furnace and the cooling space are connected.

  In the third step, the polycrystalline silicon is then transferred from the reaction furnace to the cooling space by connecting the reaction furnace and the cooling space while maintaining the temperature in the reaction furnace at 800 ° C. or higher, preferably 850 ° C. or higher. The polycrystalline silicon is taken out from the high temperature reactor to the outside of the reactor. For example, when the reactor 50 shown in FIG. 1 is used, the polycrystalline silicon 1 is cooled from the inside of the reaction furnace by opening the opening / closing part 42 and dropping the polycrystalline silicon 1 onto the silicon receiving part 43 in the cooling space. Move to space and take out polycrystalline silicon from inside the reactor to outside the reactor. At this time, the inert gas atmosphere is set in the reaction furnace and the cooling space, and the inert gas is sealed without bringing the polycrystalline silicon into contact with the outside air by sealing between the outside air and the reaction furnace and the cooling space. In the atmosphere, move from the reactor to the cooling space.

  In the third step, the polycrystalline silicon is then cooled in the cooling space.

  As the step of removing polycrystalline silicon from the reactor, by performing the third step, high temperature polycrystalline silicon can be moved to the cooling space without being brought into contact with the outside air and cooled. When taking out from the inside, it is possible to prevent the polycrystalline silicon from being oxidized by touching the outside air.

  In the method for producing polycrystalline silicon according to the present invention, in the second step, 907 to 1200 ° C., preferably 930 to 1100 ° C., the temperature in the reactor is high, and the reactor is generated in the reactor, Alternatively, the polycrystalline silicon deposited on the deposition rod can be peeled off from the wall of the reaction furnace or the deposition rod. In particular, when a vertical reaction furnace is used and a deposition rod is installed in the reaction furnace, the second step is performed, so that the temperature in the reaction furnace is high at 907 to 1200 ° C., preferably 930 to 1100 ° C. Thus, the polycrystalline silicon can be peeled off from the precipitation rod and dropped onto the bottom of the reaction furnace, and the polycrystalline silicon can be recovered from the bottom of the reaction furnace.

  Therefore, in the method for producing polycrystalline silicon according to the present invention, the polycrystalline silicon is put in the reactor at a high temperature of 800 ° C. or higher, preferably 800 to 1200 ° C., particularly preferably 850 to 1100 ° C. The 3rd process taken out out of a reaction furnace can be performed. On the other hand, in the conventional method for producing polycrystalline silicon, after the production of one batch of polycrystalline silicon is finished, the polycrystalline silicon adhering to the wall of the reactor is scraped off, or the precipitation rod on which polycrystalline silicon is deposited is used. In order to take polycrystalline silicon out of the reaction furnace by taking it out of the reaction furnace, the take-out process could not be performed unless the reaction furnace was once cooled to near room temperature. Thus, in the method for producing polycrystalline silicon according to the present invention, it is not necessary to cool and reheat the reactor which takes a long time. Instead, the supply of silicon tetrachloride or silicon tetrachloride and zinc and the subsequent reaction are performed. Since only an operation that can be performed in a short time of supplying an inert gas into the furnace is required, it is possible to shorten the stop time of the polycrystalline silicon production reaction as compared with the conventional polycrystalline silicon manufacturing method. Therefore, the polycrystalline silicon manufacturing method of the present invention has higher polycrystalline silicon manufacturing efficiency than the conventional polycrystalline silicon manufacturing method.

  Also, in the method for producing polycrystalline silicon according to the present invention, since the stop time of the production reaction of polycrystalline silicon can be extremely shortened compared with the conventional method for producing polycrystalline silicon, polycrystalline silicon in the first step Even if the production time is shortened and the first to third steps are repeated, the time for the polycrystalline silicon production reaction can be lengthened as compared with the conventional polycrystalline silicon production method. Therefore, in the method for producing polycrystalline silicon according to the present invention, the size of the reactor can be reduced without reducing the production amount of polycrystalline silicon, so that the construction cost can be reduced. Further, in the method for producing polycrystalline silicon according to the present invention, the most power consuming process of reheating the reactor is not performed, so the power consumption is small. For these reasons, the manufacturing cost of the polycrystalline silicon of the present invention is lower than that of the conventional manufacturing method of polycrystalline silicon.

  Further, in the method for producing polycrystalline silicon according to the present invention, in the second step, only silicon tetrachloride or the molar ratio of zinc to silicon tetrachloride is smaller than the molar ratio in the first step. Since silicon tetrachloride and zinc are supplied, zinc remaining on the surface of the polycrystalline silicon is consumed in the second step in the first step, so that the content of zinc in the polycrystalline silicon is reduced. Can be reduced.

  Moreover, in the manufacturing method of the polycrystalline silicon of this invention, the polycrystalline silicon which precipitated in the discharge pipe can be removed by performing a 2nd process.

  Next, the form of the vertical reactor used in the method for producing polycrystalline silicon of the present invention will be described. In the first type of vertical reaction furnace, a plurality of precipitation rods are installed in the reaction furnace, and silicon tetrachloride vapor is supplied to the upper part of the reaction furnace from the center of the reaction furnace to each precipitation rod. A reaction furnace having silicon tetrachloride vapor supply means and zinc vapor supply means for supplying zinc vapor from the side wall side to each precipitation rod, and having a discharge pipe for exhaust gas at the lower part of the reaction furnace.

  As a first form of the vertical reactor, silicon tetrachloride vapor supply means and zinc vapor supply means as the following examples (A) and (B) of silicon tetrachloride vapor supply means and zinc vapor supply means Or the reaction furnace which has (C) is mentioned.

  The form example (A) of the silicon tetrachloride vapor supply means and the zinc vapor supply means is, for example, the supply of silicon tetrachloride vapor for partitioning the supply space 132 of the silicon tetrachloride vapor as shown in FIGS. A partition wall 131 of the space, and an inner partition wall 141 and an outer partition wall 142 of the zinc vapor supply space for partitioning the zinc vapor supply space 143 surrounding the silicon tetrachloride vapor supply space 132; A silicon tetrachloride vapor supply space 132 is formed on the center side of the reactor with respect to the deposition rod 3, and a zinc vapor supply space 143 is formed on the side wall side with respect to the deposition rod 3, and a partition wall 131 of the silicon tetrachloride vapor supply space is formed. And a silicon tetrachloride vapor supply means and a zinc vapor supply means in which the partition walls 141 and 142 of the zinc vapor supply space are provided concentrically with the center of the silicon tetrachloride vapor supply space 132. In the silicon tetrachloride vapor supply means and the zinc vapor supply means shown in FIGS. 1 and 2, the silicon tetrachloride vapor supply pipe 7 is also a part of the silicon tetrachloride vapor supply means, and the zinc vapor supply pipe 8 is also provided. Part of the zinc vapor supply means.

  That is, (A) of the silicon tetrachloride vapor supply means and the zinc vapor supply means partitions the partition wall of the silicon tetrachloride vapor supply space and the zinc vapor supply space for dividing the silicon tetrachloride vapor supply space. And a partition wall of a zinc vapor supply space for forming a silicon tetrachloride vapor is formed on the center side of the reactor from the deposition rod, and a zinc vapor supply space is formed on the side wall side from the deposition rod. The silicon tetrachloride vapor supply means and the zinc vapor supply means are provided such that the partition wall of the silicon tetrachloride vapor supply space and the partition wall of the zinc vapor supply space are provided concentrically with the center of the reactor. In the embodiment (A) of the silicon tetrachloride vapor supply means and the zinc vapor supply means, the supply of silicon tetrachloride vapor so that the silicon tetrachloride vapor is uniformly diffused in the supply space of the silicon tetrachloride vapor. The connection position and the number of the pipes 7 to the partition member can be appropriately selected, and the zinc vapor supply pipe 8 can be divided into the partition member of the zinc vapor supply pipe 8 so that the zinc vapor is uniformly diffused in the zinc vapor supply space. The connection position and the number of these can be selected as appropriate.

  The silicon tetrachloride vapor supply means and the zinc vapor supply means (B) include, for example, as shown in FIG. 7, a fixing member 4, a silicon carbide rod (precipitation rod) 3 and a branch of a supply pipe for silicon tetrachloride vapor A pipe 21 and a branch pipe 22 of a zinc vapor supply pipe are fixed, and a branch pipe 21 of a silicon tetrachloride vapor supply pipe is installed closer to the center of the reactor than the silicon carbide rod (precipitation rod) 3. These are silicon tetrachloride vapor supply means and zinc vapor supply means in which a branch pipe 22 of a zinc vapor supply pipe is installed on the side wall side of the reactor from the silicon carbide rod (precipitation rod) 3. In the embodiment shown in FIG. 7, the opening 213 at the outlet of the branch pipe 21 of the silicon tetrachloride vapor supply pipe is the supply port of the silicon tetrachloride vapor, and the outlet of the branch pipe 22 of the zinc vapor supply pipe. The opening 214 is a zinc vapor supply port. Although not shown, the branch pipe 21 of the silicon tetrachloride vapor supply pipe is connected to the silicon tetrachloride vapor supply pipe 9, and the branch pipe 22 of the zinc vapor supply pipe is connected to the zinc vapor supply pipe 10. . In FIG. 7, (A) is an end view when the embodiment (B) of the silicon tetrachloride vapor supply means and the zinc vapor supply means is cut in the plane direction, and is the end face of the line xx in (B). In addition, (B) is an end view in which the vicinity of the installation site of the embodiment (B) of the silicon tetrachloride vapor supply means and the zinc vapor supply means is cut in the vertical direction.

  The silicon tetrachloride vapor supply means and the zinc vapor supply means (C) include, for example, a silicon tetrachloride vapor supply chamber 23 in which a silicon tetrachloride vapor supply port 232 is formed, as shown in FIG. A supply port 243 of zinc vapor in which a supply port 243 is formed, and a supply port 231 of silicon tetrachloride vapor is formed on the center side of the reactor from the silicon carbide rod (precipitation rod) 3, These are silicon tetrachloride vapor supply means and zinc vapor supply means in which a zinc vapor supply port 243 is formed on the side wall side of the reaction furnace from the silicon carbide rod (precipitation rod) 3. In the silicon tetrachloride vapor supply means and the zinc vapor supply means (C), a silicon carbide rod (precipitation rod) 3, a silicon tetrachloride vapor supply chamber 23, and a zinc vapor supply chamber 24 are fixed to the fixing member 4. Has been. The silicon tetrachloride vapor supply pipe 7 is connected to the silicon tetrachloride vapor supply chamber 23, and the zinc vapor supply pipe 8 is connected to the zinc vapor supply chamber 24. The hydrocarbon rod (precipitation rod) 3 is installed so as to protrude downward into the reaction furnace 20 by the fixing member 4 being hooked on the inner wall collar portion 12 formed on the inner wall of the side wall portion 31. The silicon tetrachloride vapor supply chamber 23 and the zinc vapor supply chamber 24 are installed in the upper part of the reaction furnace 20.

  The silicon tetrachloride vapor supply chamber 23 includes a cylindrical side wall 231 and circular upper and bottom members. The zinc vapor supply chamber 24 includes a cylindrical inner side wall 241, a cylindrical outer side wall 242, and a donut-shaped upper member and a bottom member. And the side wall 231, the side wall 241, and the side wall 242 are installed concentrically with the center of the reactor.

  A silicon tetrachloride vapor supply port 232 is formed in the side wall or bottom member of the silicon tetrachloride vapor supply chamber 23. A zinc vapor supply port 243 is formed in a side wall or a bottom member of the zinc vapor supply chamber 24. In FIG. 8, (A) is an end view when the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means is cut in the plane direction, and is taken along line xx in (B). It is an end surface, and (B) is an end view obtained by cutting the vicinity of the installation site of the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means in the vertical direction.

  That is, the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means includes a silicon tetrachloride vapor supply chamber in which a silicon tetrachloride vapor supply port is formed and a silicon tetrachloride vapor supply chamber. And a zinc vapor supply chamber in which a zinc vapor supply port is formed, and a silicon tetrachloride vapor supply port is formed on the center side of the reactor from the deposition rod, and supplies zinc vapor. These are silicon tetrachloride vapor supply means and zinc vapor supply means whose ports are formed on the side wall side from the deposition rod.

  In the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means, the silicon tetrachloride vapor 9 is first supplied to the silicon tetrachloride vapor supply chamber 23, and therefore, in the silicon tetrachloride vapor supply chamber 23. Spread with. After the silicon tetrachloride vapor 9 is diffused into the silicon tetrachloride vapor supply chamber 23, the silicon tetrachloride vapor 9 is supplied into the reaction furnace 20 through the silicon tetrachloride vapor supply port 232. Similarly, in the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means, the zinc vapor 10 is first supplied to the zinc vapor supply chamber 24. Spread. The zinc vapor 10 is supplied into the reaction furnace 20 from the zinc vapor supply port 243 after being diffused into the zinc vapor supply chamber 24.

  In the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means, the silicon tetrachloride vapor 9 is uniformly diffused in advance in the silicon tetrachloride vapor supply chamber 23 before being supplied to the reaction furnace 20. Therefore, for example, even if the number of the silicon tetrachloride vapor supply pipes 7 connected to the silicon tetrachloride vapor supply chamber 23 is one, each silicon tetrachloride vapor supply port 233 uniformly supplies tetrachloride. Since silicon vapor is supplied and the zinc vapor 9 is uniformly diffused in advance in the zinc vapor supply chamber 24 before being supplied to the reactor 20, for example, zinc connected to the zinc vapor supply chamber 24 Even if the number of the steam supply pipes 8 is one, the zinc steam is uniformly supplied from each zinc steam supply port 243.

  Further, in the embodiment (C) of the silicon tetrachloride vapor supply means and the zinc vapor supply means, by appropriately selecting the formation position and number of the silicon tetrachloride vapor supply port 232 and the zinc vapor supply port 243, tetrachloride is obtained. Design of the formation position of the silicon vapor supply space and the formation position of the zinc vapor is facilitated.

  In the present invention, the center side of the reaction furnace from the precipitation bar refers to a position closer to the center of the reaction furnace than the position of the precipitation bar when the reaction furnace is cut in the horizontal direction, Indicates a position closer to the side wall than the position of the deposition rod when the reactor is cut horizontally.

  In the second type of vertical reactor, a partition wall of a silicon tetrachloride vapor supply space and a partition wall of a zinc vapor supply space are provided concentrically with the center of the reactor, and the inner side is silicon tetrachloride. It is a reactor having a steam supply space and a silicon tetrachloride steam supply means and a zinc steam supply means, the outside being a zinc steam supply space.

  As a 2nd form of a vertical reactor, the reactor 26 shown in FIG.9 and FIG.10 is mentioned, for example. In the reaction furnace 26, one silicon carbide rod (precipitation rod) 3 is installed via the fixing member 4. The fixing member 4 includes a silicon tetrachloride vapor supply space partitioning member 33 for partitioning the silicon tetrachloride steam supply space 332 and a zinc steam supply space for partitioning the zinc steam supply space 342. The partition member 34 is fixed. The silicon tetrachloride vapor supply pipe 7 is connected to the partition member 33 in the silicon tetrachloride vapor supply space, and the zinc vapor supply pipe 8 is connected to the partition member 34 in the zinc vapor supply space. The fixing member 4 is hooked on the furnace inner wall collar 12 formed on the inner wall of the side wall 31, so that the silicon carbide rod 3 is installed so as to protrude downward into the reaction furnace 26. The partition member 33 in the supply space for silicon tetrachloride vapor and the partition member 34 in the supply space for zinc vapor are installed in the upper part of the reaction furnace 26. FIG. 9 is a schematic cross-sectional view of a second embodiment of the reactor used in the method for producing polycrystalline silicon according to the present invention. FIG. 10 is an end view showing the side wall (reaction furnace), the silicon carbide rod, the partition wall of the silicon tetrachloride vapor supply space, and the partition wall of the zinc vapor supply space in FIG. FIG. 6 is an end view when cut in the horizontal direction along line xx. FIG. 9 shows only a portion of the reactor installed in the polycrystalline silicon manufacturing apparatus. For example, the reaction furnace shown in FIG. 9 is fixed to the surface plate 41 by a fixing part 39 at the lower end of the side wall instead of the reaction furnace 20 shown in FIG.

  In the reaction furnace 26, the partition member 33 in the silicon tetrachloride vapor supply space is composed of a cylindrical partition wall 331 and a circular upper member. The partition member 34 in the zinc vapor supply space includes a cylindrical partition wall 341 and a donut-shaped upper member. The partition wall 331 and the partition wall 341 are installed concentrically with the center of the silicon tetrachloride vapor supply space 332. In the reaction furnace 26, the zinc vapor supply space on the silicon tetrachloride vapor supply space side is partitioned by a partition wall 331.

  In the reaction furnace 26, the silicon tetrachloride vapor 9 is first supplied to the partition member 33 in the silicon tetrachloride vapor supply space, and therefore, in the silicon tetrachloride vapor supply space 332 partitioned by the partition member 33. Spread. After the silicon tetrachloride vapor 9 is diffused into the silicon tetrachloride vapor supply space 332, the silicon tetrachloride vapor 9 is supplied into the reactor 20 through the silicon tetrachloride vapor supply port 333. In addition, since the zinc vapor 10 is first supplied to the partition member 34 of the zinc vapor supply space, the zinc vapor 10 diffuses into the zinc vapor supply space 342 partitioned by the partition member 34. The zinc vapor 10 is supplied into the reaction furnace 20 from the zinc vapor supply port 343 after being diffused into the zinc vapor supply space 342. As a result, the supply position of the silicon tetrachloride vapor 9 to the precipitation rod 3 is closer to the supply position of the zinc vapor 10. Further, around the precipitation rod 3, silicon tetrachloride vapor is supplied so as to surround the precipitation rod 3, and zinc vapor is supplied so as to surround the silicon tetrachloride vapor with zinc vapor. In the reaction furnace 26, the silicon tetrachloride vapor supply port 333 has a donut shape, and the zinc vapor supply port 343 has a donut shape.

  That is, the second type of vertical reactor is a reactor in which the supply position of silicon tetrachloride vapor into the reaction furnace is closer to the precipitation rod than the supply position of zinc vapor. Furthermore, the second form of the vertical reactor is preferably provided with a partition wall of the silicon tetrachloride vapor supply space and a partition wall of the zinc vapor supply space concentrically with the center of the reactor, A reactor having silicon tetrachloride vapor supply means and zinc vapor supply means whose inner side is a supply space for silicon tetrachloride vapor and whose outer side is a supply space for zinc vapor.

  Moreover, the reactor used with the manufacturing method of the polycrystalline silicon of this invention may have the insertion container installed in the reactor. Examples of the material for the insertion container include quartz such as transparent quartz, opaque quartz, and sintered quartz, silicon carbide, and silicon nitride. From the viewpoint of strength, silicon carbide and silicon nitride are preferable, and due to temperature gradients. Quartz and silicon nitride are preferable from the viewpoint that cracks are unlikely to occur.

  The manufacturing apparatus for performing the polycrystalline silicon manufacturing method of the present invention is not particularly limited as long as it is a manufacturing apparatus capable of performing the polycrystalline silicon manufacturing method of the present invention, as shown in FIG. Manufacturing equipment is preferred.

That is, the preferred embodiment of the polycrystalline silicon production apparatus of the present invention has a silicon tetrachloride vapor supply pipe and a zinc vapor supply pipe in the upper part, and an exhaust gas exhaust pipe in the lower part. A reaction furnace for reacting silicon tetrachloride and zinc to produce polycrystalline silicon, and a cooling unit installed on the bottom side of the reaction furnace to form a cooling space for an inert gas atmosphere,
Between the reactor and the cooling section, when silicon tetrachloride and zinc are reacted in the reactor, the reactor is closed so that the gas in the reactor does not leak into the cooling section, and After the reaction between silicon tetrachloride and zinc, the structure is opened so that the polycrystalline silicon can move from the reaction furnace to the cooling space.
Is an apparatus for producing polycrystalline silicon.

  The polycrystalline silicon production apparatus of the present invention is a vertical reactor and is the same as the vertical reactor used in the polycrystalline silicon production method of the present invention.

  In the polycrystalline silicon manufacturing apparatus of the present invention, a cooling unit is installed on the bottom side of the reaction furnace, and an inert gas atmosphere is cooled on the bottom side of the reaction furnace by supplying an inert gas to the cooling unit. A space can be formed.

  In the polycrystalline silicon manufacturing apparatus of the present invention, the inside of the reaction furnace and the cooling part and the outside air are sealed so that the outside air does not enter the reaction furnace and the cooling part. And, when silicon tetrachloride and zinc are reacted in the reaction furnace between the polycrystalline silicon reaction furnace and the cooling part of the present invention, the gas in the reaction furnace does not leak into the cooling part. After the reaction between silicon tetrachloride and zinc is closed, the structure is opened so that polycrystalline silicon can move from the reaction furnace to the cooling space. Therefore, after the reaction between silicon tetrachloride and zinc in the reaction furnace, the polycrystalline silicon can be moved to the cooling space without contacting the outside air while keeping the temperature in the reaction furnace high. .

  In the polycrystalline silicon manufacturing apparatus of the present invention, it is preferable that the structure between the inside of the reaction furnace and the cooling unit be shielded from the viewpoint of increasing the thermal efficiency of the reaction furnace. For example, in the embodiment shown in FIG. 1, by installing a heat insulating material 47 in the opening / closing part 42, that is, by installing a heat insulating material between the inside of the reaction furnace and the cooling part, The space is shielded from heat.

The polycrystalline silicon obtained by the method for producing polycrystalline silicon of 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 of the present invention is 0.01-1 mass ppm, preferably 0.01-0.8 mass ppm, particularly preferably 0.01-0. 0.5 ppm by mass. 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 according to the present invention is a rod shape having a large diameter, a granular shape or a plate shape, or a shape in which a plurality of rod shapes having a large diameter, a granular shape or a plate shape are attached. The diameter is not 3 μm or less. The size of the polycrystalline silicon is preferably 100 μm or more, particularly preferably 500 μm or more, and more preferably 1,000 μm or more. As the polycrystalline silicon, 50% by mass or more is preferably polycrystalline silicon that does not pass through a screen of 100 μm mesh size, and 50% by mass or more is particularly preferably polycrystalline silicon that does not pass through a screen of 500 μm mesh size. .

  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
The following first to third steps were repeated four times.
(First step)
Using the polycrystalline silicon manufacturing apparatus 50 shown in FIG. 1, in the following reactor, together with nitrogen gas, zinc vapor heated and vaporized from a zinc vapor supply pipe to 950 ° C. was reacted at a supply rate of 52 g / min. The silicon tetrachloride vapor supplied to the furnace and vaporized by heating to 950 ° C. from the silicon tetrachloride vapor supply pipe is supplied to the reactor at a supply rate of 74 g / min. Then, the reaction between silicon tetrachloride and zinc was carried out for 22 hours. At this time, the molar ratio of zinc to silicon tetrachloride is 1.82.
<Reactor (in the embodiment shown in FIG. 1, the number of silicon carbide rods installed is three)>
Reactor: Quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm is used. Silicon carbide rod: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon mass ratio is 85:15, outer diameter 16 mm x length 390 mm, number 3 (installed at regular intervals on an arc centered on the center of the reactor)
Internal diameter of discharge pipe at reactor outlet: 100mm
Diameter of partition wall portion of silicon tetrachloride vapor supply space: inner diameter 50 mm
Diameter of partition wall part of zinc vapor supply space: silicon carbide rod side outer diameter 180 mm, side wall side inner diameter 230 mm

(Second step)
After performing the first step, then, with the temperature in the reaction furnace being 950 ° C., only silicon tetrachloride vapor was supplied into the reaction furnace at a supply rate of 74 g / min for 0.5 hour. At this time, the molar ratio of zinc to silicon tetrachloride is zero.

(Third process)
After performing the second step, nitrogen gas was then supplied into the reaction furnace at a supply rate of 50 L / min for 0.5 hours while the temperature in the reaction furnace was 950 ° C. In parallel, nitrogen gas was supplied into the cooling unit 44 to make the cooling space 45 a nitrogen gas atmosphere. The temperature in the cooling space 45 at this time was 50 ° C. Next, the supply of nitrogen gas into the reaction furnace is stopped, the discharge pipe 6 is closed, and the temperature in the reaction furnace is 950 ° C., the opening / closing part 42 is opened, and the polycrystalline silicon in the reaction furnace is cooled to a cooling space. It was dropped into 45 and the polycrystalline silicon was cooled in the cooling space 45 to obtain polycrystalline silicon. Further, after the polycrystalline silicon was dropped into the cooling space 45, the opening / closing part 42 was closed.

(result)
The yield of polycrystalline silicon in one cycle was 10.35 kg on average, and 41.4 kg of polycrystalline silicon was recovered in total for four cycles. The total time (total reaction time) of 4 cycles in the first step was 88 hours. The zinc content in the polycrystalline silicon was 0.2 ppm.

(Comparative Example 1)
In the same reactor as in Example 1, together with nitrogen gas, zinc vapor heated and vaporized from a zinc vapor supply pipe to 950 ° C. was supplied into the reactor at a supply rate of 52 g / min. The silicon tetrachloride vapor vaporized by heating to 950 ° C. from the supply pipe is supplied into the reaction furnace at a supply rate of 74 g / min, and the reaction furnace is brought to 950 ° C. to react silicon tetrachloride with zinc. , 60 hours. At this time, the molar ratio of zinc to silicon tetrachloride is 1.82.
Next, nitrogen gas was supplied into the reaction furnace for 1 hour at a supply rate of 50 L / min with the inside of the reaction furnace at 950 ° C.

  The reactor was then allowed to cool to 25 ° C. At this time, it took 24 hours for the temperature in the reactor to drop to 25 ° C.

  Next, after opening the lid of the reaction furnace and removing the attachment members such as the supply pipe for silicon tetrachloride vapor and the supply pipe for zinc vapor, the silicon carbide rod together with the fixed member is taken out of the reaction furnace, The silicon adhering to the inner wall was scraped off. Next, a silicon carbide rod prepared separately is fixed to the fixing member, the fixing member is installed in the reaction furnace, and attached members such as a silicon tetrachloride vapor supply pipe and a zinc vapor supply pipe are attached, The reactor lid was closed. It took 6 hours from opening the reactor lid to closing it again.

  Next, the inside of the reaction furnace was heated up to 950 ° C. At this time, the time required for temperature increase was 5 hours.

(result)
28 kg of polycrystalline silicon was recovered. The zinc content in the polycrystalline silicon was 2.1 ppm.

  When the cycle from the start of supply of silicon tetrachloride vapor and zinc vapor into the reactor to the point when the supply of silicon tetrachloride vapor and zinc vapor into the reactor of the next batch can be performed is one cycle In Example 1, four cycles were performed, and the time required for the four cycles was 96 hours. In Comparative Example 1, one cycle was performed, and the time required for one cycle was 96 hours.

(Example 2)
The following first to third steps were repeated four times.
(First step)
Using the polycrystalline silicon manufacturing apparatus 50 shown in FIG. 1, in the following reactor, together with nitrogen gas, zinc vapor heated and vaporized from a zinc vapor supply pipe to 950 ° C. was reacted at a supply rate of 52 g / min. The silicon tetrachloride vapor supplied to the furnace and vaporized by heating to 950 ° C. from the silicon tetrachloride vapor supply pipe is supplied to the reactor at a supply rate of 74 g / min. Then, the reaction between silicon tetrachloride and zinc was carried out for 22 hours. At this time, the molar ratio of zinc to silicon tetrachloride is 1.82.
<Reactor (in the embodiment shown in FIG. 1, the number of silicon carbide rods installed is three)>
Reactor: Quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm is used. Silicon carbide rod: silicon-impregnated silicon carbide rod, silicon carbide: impregnated silicon mass ratio is 85:15, outer diameter 16 mm x length 390 mm, number 3 (installed at regular intervals on an arc centered on the center of the reactor)
Internal diameter of discharge pipe at reactor outlet: 100mm
Diameter of partition wall portion of silicon tetrachloride vapor supply space: inner diameter 50 mm
Diameter of partition wall part of zinc vapor supply space: silicon carbide rod side outer diameter 180 mm, side wall side inner diameter 230 mm

(Second step)
After performing the first step, in the state where the temperature in the reactor is 950 ° C., silicon tetrachloride vapor is supplied into the reactor at a supply rate of 74 g / min, and zinc vapor is supplied at a supply rate of 26 g / min. Feed for 0.5 hours. At this time, the molar ratio of zinc to silicon tetrachloride is 0.91.

(Third process)
After performing the second step, nitrogen gas was then supplied into the reaction furnace at a supply rate of 50 L / min for 0.5 hours while the temperature in the reaction furnace was 950 ° C. In parallel, nitrogen gas was supplied into the cooling unit 44 to make the cooling space 45 a nitrogen gas atmosphere. The temperature in the cooling space 45 at this time was 50 ° C. Next, the supply of nitrogen gas into the reaction furnace is stopped, the discharge pipe 6 is closed, and the temperature in the reaction furnace is 950 ° C., the opening / closing part 42 is opened, and the polycrystalline silicon in the reaction furnace is cooled to a cooling space. It was dropped into 45 and the polycrystalline silicon was cooled in the cooling space 45 to obtain polycrystalline silicon. Further, after the polycrystalline silicon was dropped into the cooling space 45, the opening / closing part 42 was closed.

(result)
The yield of polycrystalline silicon in one cycle was 10.52 kg on average, and 42.08 kg of polycrystalline silicon was recovered in total for four cycles. The total time (total reaction time) of 4 cycles in the first step was 88 hours. The zinc content in the polycrystalline silicon was 0.25 ppm.

  Therefore, if the time required for producing polycrystalline silicon is the same, the production amount of polycrystalline silicon in Examples 1 and 2 is larger than that in Comparative Example 1, so that the production of polycrystalline silicon according to the present invention is performed. According to the method, it was found that a large amount of polycrystalline silicon can be produced. Further, when compared in terms of the amount of polycrystalline silicon produced per cycle, Examples 1 and 2 are smaller than Comparative Example 1, so that according to the method for producing polycrystalline silicon of the present invention, It has been found that the size of the reactor for production can be reduced. Further, since the purity of polycrystalline silicon is higher in Examples 1 and 2 than in Comparative Example 1, it can be seen that high-purity polycrystalline silicon can be produced according to the polycrystalline silicon production method of the present invention. It was.

  According to the present invention, polycrystalline silicon deposited in the reaction furnace can be easily taken out from the reaction furnace, the production efficiency is increased, and the reaction furnace can be made small, so that polycrystalline silicon can be produced at low cost. it can.

DESCRIPTION OF SYMBOLS 1 Polycrystalline silicon 2 Space in reactor 3 Silicon carbide rod 4 Fixed member 5 Heater 6 Exhaust pipe 7 Silicon tetrachloride vapor supply pipe 8 Zinc vapor supply pipe 9 Silicon tetrachloride vapor 10 Zinc vapor 11 Exhaust gas 12 Furnace wall Collar members 13, 33 Partition members 14, 34 of silicon tetrachloride vapor supply space Partition members 20, 26 of zinc vapor supply space Reactor 21 Branch pipe of silicon tetrachloride vapor supply pipe 22 Branch of zinc vapor supply pipe Tube 23 Silicon tetrachloride vapor supply chamber 24 Zinc vapor supply chamber 31 Reactor side wall 32 Cover portion 39 Fixed portion 41 at the lower end of the side wall portion Surface plate 42 Opening and closing portion 43 Silicon receiving portion 44 in cooling space Cooling portion 45 Cooling space 46 Reactor Silicon Receiving Portion 47 Heat Insulating Material 50 Polycrystalline Silicon Manufacturing Device 131 Silicon Tetrachloride Vapor Supply Space Partition Walls 132 and 332 Silicon Tetrachloride Vapor Supply Space 133 and 21 232, 333 Silicon tetrachloride vapor supply port 141 Compartment wall 142 of zinc vapor supply space inside Compartment wall 143, 342 of zinc vapor supply space outside Zinc vapor supply space 144, 214, 243, 343 Zinc vapor Supply port 231 Side wall 241 Center side wall 242 Side wall side wall 331 Silicon tetrachloride vapor supply space partition wall 341 Zinc vapor supply space partition wall

Claims (12)

A first step of reacting silicon tetrachloride and zinc in a reaction furnace to produce polycrystalline silicon in the reaction furnace;
At 907-1200 ° C., only silicon tetrachloride is supplied into the reactor, or the molar ratio of zinc to silicon tetrachloride is less than the molar ratio in the first step. A second step of supplying silicon and zinc;
The temperature in the reaction furnace is 800 ° C. or higher, the reaction furnace is made an inert gas atmosphere, and then the polycrystalline silicon is cooled from the reaction furnace at 800 ° C. or higher to the inert gas atmosphere cooling space connected to the reaction furnace. A third step of taking polycrystalline silicon out of the reactor from the reactor and cooling it, by moving to
A method for producing polycrystalline silicon, comprising:   The method for producing polycrystalline silicon according to claim 1, wherein the molar ratio of zinc to silicon tetrachloride in the second step is 0 to 1.5.   3. The method for producing polycrystalline silicon according to claim 1, wherein in the first step, silicon tetrachloride and zinc are reacted by supplying silicon tetrachloride vapor and zinc vapor. 4.   The polycrystalline reactor according to any one of claims 1 to 3, wherein the reactor is a vertical reactor in which silicon tetrachloride vapor and zinc vapor are supplied from above and exhaust gas is discharged from below. Silicon manufacturing method.   The method for producing polycrystalline silicon according to claim 4, wherein a precipitation rod is installed in the reaction furnace.   6. The production of polycrystalline silicon according to claim 5, wherein the reaction furnace is a reaction furnace in which the supply position of silicon tetrachloride vapor into the reaction furnace is closer to the precipitation rod than the supply position of zinc vapor. Method.   The reaction furnace is provided with a partition wall of a supply space of silicon tetrachloride vapor and a partition wall of a supply space of zinc vapor concentrically with the center of the reaction furnace, and the inside is a supply space of silicon tetrachloride vapor, 7. The method for producing polycrystalline silicon according to claim 6, wherein the reactor is a reaction furnace having a silicon tetrachloride vapor supply means and a zinc vapor supply means, the outside of which is a zinc vapor supply space.   The reaction furnace is provided with a plurality of precipitation rods in the reaction furnace, and a silicon tetrachloride vapor supply means for supplying silicon tetrachloride vapor to the upper portion of the reaction furnace from the center side of the reaction furnace to each precipitation rod And a zinc vapor supply means for supplying zinc vapor from the side wall side to each precipitation rod, and a reaction furnace having an exhaust gas discharge pipe at the bottom of the reaction furnace. The method for producing polycrystalline silicon according to claim 1.   The silicon tetrachloride vapor supply means and the zinc vapor supply means have a partition wall of a silicon tetrachloride vapor supply space for dividing a silicon tetrachloride vapor supply space on the center side of the reactor from the deposition rod, and A partition wall of the zinc vapor supply space for partitioning the zinc vapor supply space on the side wall side from the precipitation rod, and a partition wall of the silicon tetrachloride vapor supply space on the precipitation rod side and zinc on the precipitation rod side The partition wall of the steam supply space is a silicon tetrachloride vapor supply means and a zinc vapor supply means provided concentrically with the center of the reaction furnace. Production method.   The method for producing polycrystalline silicon according to any one of claims 5 to 9, 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 11. A method for producing polycrystalline silicon according to Item 10. It has a supply pipe for silicon tetrachloride vapor and a supply pipe for zinc vapor in the upper part, and an exhaust gas discharge pipe in the lower part, and reacts silicon tetrachloride with zinc in the reaction furnace to produce polycrystalline silicon. A reaction furnace, and a cooling unit installed on the bottom side of the reaction furnace and forming a cooling space of an inert gas atmosphere,
Between the reactor and the cooling section, when silicon tetrachloride and zinc are reacted in the reactor, the reactor is closed so that the gas in the reactor does not leak into the cooling section, and After the reaction between silicon tetrachloride and zinc, the structure is opened so that the polycrystalline silicon can move from the reaction furnace to the cooling space.
An apparatus for producing polycrystalline silicon.