JP2008037735A - Apparatus for manufacturing silicon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-purity silicon pure enough to be used in a solar battery, by the reduction of silicon tetrachloride by zinc gas. <P>SOLUTION: In the manufacturing method, the zinc gas or a zinc-containing gas essentially comprising zinc gas is constantly sent to a reactor to induce a zinc gas atmosphere therein, silicon tetrachloride in a liquid state is introduced to the reactor, a zinc reduction reaction is induced to produce a silicon, and only a reaction product gas is discharged from the reactor at the reactor terminal so that the produced silicon is locally accumulated inside the reactor. A part where the produced silicon is locally accumulated inside the reactor is a silicon melt-retaining tank which is kept at a temperature equal to or higher than the melting point of the silicon. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to an apparatus for producing silicon for obtaining high-purity silicon by reducing silicon tetrachloride, which can obtain silicon used for solar cells and electronic components with low energy consumption, with metallic zinc.

  Currently, the production of high-purity silicon is a method called the Siemens method, in which crude silicon is treated with hydrogen chloride to produce trichlorosilane, dichlorosilane, or monochlorosilane, and these silane compounds are used as raw materials for chemical vaporization. Manufactured by phase growth method. By this Siemens method, extremely high purity silicon can be obtained, but in the process of producing each silane compound as an intermediate substance, it is inevitable that silicon tetrachloride, which is more stable than the silane compound, is produced as a by-product, The target yield of silanes is 50% or less. Furthermore, not only is the reaction for silicon production very slow, but the yield is never good because silanes are converted into more stable silicon tetrachloride in the reaction tower before silicon is produced. For this reason, a large-scale facility is required to obtain a certain production capacity, so the burden of capital investment is heavy. In addition, the power consumption required for the production is estimated to be 350 kWh per 1 kg of silicon. ing. High-purity silicon manufactured by such a manufacturing method is excellent for highly integrated electronic devices with high added value. However, silicon used for solar cells and IC-tags whose market is expected to expand rapidly in the future. The material is too expensive and is over quality. Furthermore, the treatment of silicon tetrachloride, which is a by-product generated in a large amount by this production method, has become a problem. This silicon tetrachloride has been conventionally used as a raw material for quartz glass and the like since it can be obtained by decomposing with water to obtain high-quality silicon dioxide oxide. However, with the increase in silicon production, it has become excessive.

  As an alternative method for producing silicon, a method using silicon tetrachloride as a raw material has been known for a long time. That is, this is a method for producing high-purity silicon by reducing silicon tetrachloride with zinc metal at a high temperature. In the 1950's, DuPont USA was put into practical use, where high-purity silicon was obtained by reacting silicon tetrachloride and zinc in the gas phase at a temperature of 950 ° C. However, it is difficult to obtain a high purity comparable to that of the Siemens method, and further, there are problems in the separation of the reaction by-product zinc chloride and silicon, and the treatment of zinc chloride produced in large quantities. For this reason, this zinc chloride reduction method has been forgotten as the silicon production method based on the Siemens method using trichlorosilane as a raw material has been improved.

  On the other hand, Patent Document 1 and Patent Document 2 show a method for obtaining high-purity silicon by reacting molten zinc with silicon tetrachloride gas. In this method, silicon produced in a batch system must be separated from zinc and zinc chloride, and the manufacturing process becomes complicated and the problem of contamination of impurities accompanying the separation operation remains. Patent Document 3 and Patent Document 4 attempt to review the reduction reaction conditions in the gas phase and mention the treatment of reaction by-product zinc chloride by electrolysis, but can be used industrially. There is almost no description about the specific technical contents.

Japanese Patent Laid-Open No. 11-060228 Japanese Patent Laid-Open No. 11-092130 JP 2003-034519 A JP 2003-095633 A

  From the viewpoint of realizing easy and efficient removal of silicon as a reaction product in Patent Document 5 to Patent Document 10, the present inventors have preferred reaction temperature in a reduction reaction of silicon tetrachloride gas with zinc gas, The reaction tower inner wall temperature, raw material molar ratio, and carrier gas are shown, and it has been proposed to introduce a product take-out mechanism that can take out high-purity silicon in a liquid state. By separating zinc from by-product zinc chloride by molten salt electrolysis and reusing it, these inventions can be reused to open a closed system that shuts off the reaction system from outside air, enabling efficient continuous operation. It was. The energy consumption of the high purity silicon production system based on these inventions can be reduced from about 1/10 to 1/5 of the energy required for high purity silicon production by the Siemens method. Silicon obtained by this production system is sufficient for solar cells, although its purity is slightly inferior to that of ultra-high purity silicon produced by the Siemens method.

JP 2003-342016 A JP 2004-010472 A JP 2004-035382 A JP 2004-099421 A Japanese Patent Laid-Open No. 2004-210594 JP 2004-284935 A

  Thus, according to the prior art, an apparatus capable of obtaining high-purity silicon having sufficient purity for solar cells by continuous operation by reduction reaction of silicon tetrachloride with zinc gas can be realized. However, this reduction reaction is a reaction that generates 2 mol of zinc chloride gas and 1 mol of solid silicon from 1 mol of silicon tetrachloride gas and 2 mol of zinc gas. Before and after the reaction, the gas involved in the reaction is 1 Decrease by mole. If an inert gas or the like is used as the carrier gas and the reaction is caused in a state where at least one of the source gases is dilute, the volume fluctuation is relatively small, and the pressure fluctuation in the reaction system can be ignored. However, when the raw material gas is sufficiently introduced into the reaction tube in order to improve the silicon production efficiency, the pressure fluctuation accompanying the reduction reaction cannot be ignored and it becomes difficult to keep the reaction system stable. The present invention provides a production apparatus capable of sufficiently supplying raw materials to obtain high silicon production efficiency and maintaining the stability of a reaction system in the production of high purity silicon by zinc reduction of silicon tetrachloride. It is aimed.

  In order to solve the above-described problems, the present invention introduces silicon tetrachloride in a liquid state into a reaction tower in which zinc gas or a zinc mixed gas mainly composed of zinc gas is constantly fed to form a zinc gas atmosphere. Then, a zinc reduction reaction is caused, and the silicon produced by this reaction is discharged at the terminal end of the reaction tower only the reaction product gas to the outside of the reaction tower, and the produced silicon is locally accumulated in the reaction tower. It is characterized by that. In the introduction of liquid silicon tetrachloride into the reaction tower, a silicon tetrachloride introduction pipe is provided in the reaction tower, and silicon tetrachloride is discharged into the reaction tower in the form of a mist or in the form of droplets. Drop inside. In the reaction tower according to the present invention, the portion where the zinc reduction reaction occurs is a horizontal reaction tower in which the zinc mixed gas and the reaction product gas flow in the lateral direction, and transports silicon produced by the zinc reduction reaction together with the reaction product gas. And it guide | induces to the vertical separation tower connected to the horizontal reaction tower, It is characterized by isolate | separating reaction product gas and production | generation silicon | silicone in this vertical separation tower. Alternatively, the reaction tower according to the present invention is a vertical reaction tower in which the zinc reduction gas in the reaction tower is introduced so that the zinc mixed gas becomes a swirl flow, and the liquid introduced into the swirl flow The silicon produced by the zinc reduction reaction of the state silicon tetrachloride is separated from the reaction product gas and the produced silicon by a cyclone separator directly connected to the vertical reaction tower, and the reaction product gas is discharged upward or downward. The part where the produced silicon of the present invention is locally accumulated in the reaction tower is a silicon melting holding tank, which is held at a temperature equal to or higher than the melting temperature of silicon.

  In the high purity silicon production apparatus according to the present invention, silicon tetrachloride is introduced in a liquid state into a reaction tower filled with zinc gas. Since the temperature in the reaction tower according to the present invention is maintained at 1000 ° C. or higher, silicon tetrachloride introduced into the reaction tower tends to vaporize rapidly, but the rate of the zinc reduction reaction of silicon tetrachloride is Because it is extremely fast, it is reduced by zinc gas before being vaporized and expanded explosively, changing to silicon and zinc chloride. The volume of liquid silicon tetrachloride is extremely small compared to high-temperature gas, and in the reduction reaction process according to the present invention, the volume of 1 mol of solid silicon and the volume of liquid silicon tetrachloride can be ignored. In particular, it may be considered that 2 moles of zinc gas is changed to 2 moles of zinc chloride gas. Therefore, if the high-purity silicon production apparatus of the present invention is provided, even if a large amount of raw material is charged into the reaction tower, a large volume fluctuation does not occur before and after the reaction, and the pressure fluctuation in the reaction tower does not occur. It is possible to realize a stable reaction with suppressed. In addition, silicon produced directly from liquid silicon tetrachloride tends to be in the form of a fiber with microcrystals connected, and as a result, powdered silicon is often formed. Compared with the prior art, reactive gas and purified silicon are formed. There is also an effect that can be easily separated.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an embodiment of a high-purity silicon production apparatus in which a horizontal reaction column and a vertical separation column are combined.

  In the high-purity silicon production apparatus of FIG. 1, the metallic zinc melted in the zinc melting section 1 is sent to the zinc evaporation section 2 maintained at a temperature equal to or higher than the boiling point of zinc, where it is instantly vaporized and dissolved in the zinc gas. Become. Here, the melting of zinc and the zinc gasification part are separated because the flow rate control of the high temperature liquid is much easier than the flow rate control in the high temperature steam state. With this configuration, the amount of zinc gas introduced into the reaction tower can be strictly controlled. The generated zinc gas is heated and adjusted to a predetermined temperature of 1050 ° C. to 1300 ° C. in the zinc gas heating unit 3 and blown into the horizontal reaction tower 5 from the zinc supply nozzle 4. At this time, in order to control the gas flow, a small amount of an inert gas such as argon may be added as a carrier gas in addition to the zinc gas. However, in order to efficiently produce a large amount of silicon with a relatively small apparatus, it is desirable to supply a sufficient amount of zinc gas without introducing a carrier gas. At this time, the zinc gas may be supplied so as to be a laminar flow that flows almost uniformly in the reaction tower, or may be supplied so as to be a swirl flow. The pressure of the zinc gas is set to approximately atmospheric pressure or slightly higher than atmospheric pressure, and the pressure difference generated by the pressure drop caused by the gas temperature drop or volume change due to liquefaction at the reaction gas outlet or processing part is used. Thus, a gas flow can be generated.

The silicon tetrachloride held in the silicon tetrachloride holding unit 6 is sent in a liquid state toward the silicon tetrachloride supply nozzle 8 by the liquid feed pump 7 and sprayed or dripped in the horizontal reaction tower 5 in the form of a mist. Is done. Since the temperature in the horizontal tower is maintained at 1000 ° C. or higher, silicon tetrachloride introduced into the reaction tower tends to vaporize rapidly, but SiCl ₄ + 2Zn → Si + 2ZnCl _{2 on} the surface of the silicon tetrachloride droplet. The zinc reduction reaction of silicon tetrachloride occurs. Since the rate of this reaction is extremely high, it is reduced by zinc gas before being vaporized and explosively expanded, and converted into a fine silicon crystal solid and zinc chloride. At this time, if the zinc gas is not sufficiently supplied around the silicon tetrachloride supply nozzle, there is a concern that the pressure in the reaction tube may become unstable due to silicon tetrachloride that rapidly vaporizes and expands. However, a laminar flow or swirling flow of zinc gas with a sufficient flow rate is generated in the horizontal reaction tube, and by maintaining a sufficient zinc gas atmosphere, the reduction reaction proceeds rapidly and silicon tetrachloride vaporizes and expands. Since the reaction is completed before, a large pressure fluctuation does not occur, and a stable reaction can be realized. In addition, although the reaction atmosphere temperature is extremely high depending on the zinc gas atmosphere, the actual temperature of the reaction that occurs on the surface of silicon tetrachloride is slightly lower than that, so the concentration of impurities that can be mixed in, including zinc remaining in the generated silicon Can be kept very low.

  At this time, if the inner surface of the quartz glass of the horizontal reaction tower is kept at 1050 ° C. to 1300 ° C., fibrous or particulate silicon silicon generated in laminar flow or swirling flow adheres to the inner surface of the reaction tower. Therefore, silicon produced in the horizontal reaction tower is not left and is transported to the vertical separation tower 9 together with unreacted zinc gas and zinc chloride gas as the reaction product gas.

  The vertical separation column 9 of the high-purity silicon production apparatus shown in FIG. 1 is a cyclone type separation column, and a reaction gas containing generated silicon is introduced into the vertical separation column so as to form a swirling flow. . As a result, the solid silicon is separated from the reaction gas and accumulated in the lower part of the vertical separation tower. On the other hand, the reaction gas containing zinc reverses downward to form a swirling upward flow, and is discharged out of the separation tower from the separation gas outlet 10 above the vertical separation unit. At this time, the gas velocity in the cyclone separator is desirably 1 to 5 m / sec. However, it is possible to further increase the separation efficiency by increasing the gas velocity. . The vertical separation column is made of quartz glass, and the temperature is preferably 910 to 1200 ° C., and particularly preferably 950 to 1100 ° C. in order to cause a stable reduction reaction.

  The mixed gas of zinc gas and zinc chloride gas discharged from the separation gas outlet 10 is sent to the separation gas processing device 11 and processed. Although this treatment apparatus may be used to detoxify and recover zinc and zinc chloride, it is preferable to use a zinc chloride molten salt electrolysis apparatus. First, while reducing the gas temperature between the separation gas outlet 10 and the electrolytic cell, the mixed gas of zinc and zinc chloride is directly sent to the electrolytic cell and liquefied in the electrolytic cell, thereby utilizing the difference in specific gravity. Separating into zinc and zinc chloride. Subsequently, the zinc chloride is separated into zinc and chlorine by molten salt electrolysis. By returning the zinc melt obtained in this manner to the zinc melting portion 1, zinc can be reused. On the other hand, chlorine can be used as a raw material for producing silicon tetrachloride.

  The separated silicon collected in the lower silicon melting and holding tank 12 is melted and taken out to the outside. As shown in FIG. 1, if the silicon melting and holding tank 12 has a two-tank structure with a partition 13 having a bottom penetrating in the center, the molten silicon produced is prevented while preventing the outside air from entering the reaction tower. Since 14 can be taken out to the outside, the high-purity silicon production apparatus according to the present invention can be continuously operated. Of course, even if it is a device that once removes the particulate, acicular, and fibrous silicon accumulated in the lower part without providing a dissolution / holding mechanism at the bottom, it is a stable feature that is a feature of the present invention. The characteristics of realizing the reduced reaction are not lost. The material of the holding tank in the case of fusing silicon at the lower part of the vertical separation tower may be any material as long as it can be used at 1414 ° C. or higher, which is higher than the melting point of silicon. However, in order to avoid contamination of the generated silicon from the holding tank wall surface material, it is effective to cool the holding tank wall surface and cover the wall with solid silicon while heating and melting silicon itself by induction heating. Thereby, since the molten silicon does not substantially contact the holding tank wall surface, high purity can be maintained. At this time, the material of the holding tank is preferably a metal such as tantalum having good heat conduction and stability, or a stable ceramic such as stabilized zirconia or mullite.

  Silicon produced directly from the liquid silicon tetrachloride of the present invention is often in the form of fibers, and since the fibers or fine particles are mostly composed of a collection of single crystals, the silicon production itself is a refining process, High purity silicon is easy to obtain. Further, the melting and heating in the reactor removes zinc and zinc chloride having a low boiling point more completely, and high-purity silicon can be obtained as compared with the prior art. Of course, an inert gas such as argon can be passed through the molten silicon holding tank to remove zinc or zinc chloride that may remain in the melt more completely.

  FIG. 2 is a schematic view of a silicon production apparatus according to the present invention using the vertical reaction column 15. The upper part is a reaction part 16 for causing a reduction reaction, and the lower part is a separation part 17 for separating the generated solid silicon and the reaction gas. As in FIG. 1, the metallic zinc melted in the zinc melting part 1 is sent to the zinc gasification part 2 maintained at a temperature equal to or higher than the boiling point of zinc, where it is instantly vaporized and becomes zinc gas. The generated zinc gas is heated and adjusted to a predetermined temperature of 1050 ° C. to 1300 ° C. by the zinc gas heating unit 3 and blown into the vertical reaction tower 15 from the zinc supply nozzle 4. At this time, the zinc gas is blown along the circumferential direction of the reaction tower to form a swirling flow necessary for cyclone separation.

  The silicon tetrachloride held in the silicon tetrachloride holding unit 6 is pumped toward the silicon tetrachloride supply nozzle 8 in a liquid state by the liquid feed pump 7 and sprayed or dripped from the top into the vertical reaction column 15 in the form of a mist. Is done. Since the temperature in the vertical column is maintained at 1000 ° C. or more, silicon tetrachloride introduced into the reaction column tends to vaporize rapidly, but the rate of zinc reduction reaction of silicon tetrachloride is extremely fast. Before being vaporized and explosively expanded, it is reduced by the zinc gas that has become a swirling flow having a sufficient flow rate, and is stably transformed into silicon and zinc chloride. At this time, if the inner surface of the quartz glass of the horizontal reaction tower is maintained at 1050 ° C. to 1300 ° C., fibrous or fine particle silicon generated in the swirling flow will not adhere to the inner surface of the reaction tower, It accumulates in the silicon melting and holding tank 12 at the lower part of the separation part. On the other hand, the reaction gas containing zinc reverses downward to form a swirling upward flow, and is discharged out of the separation tower from the separation gas outlet 10 above the vertical separation unit. The silicon accumulated in the silicon melting and holding tank is taken out as a melt.

  With these configurations according to the present invention, it is possible to generate silicon continuously and stably. Using these devices, the silicon production shown in the following examples was attempted.

  An attempt was made to produce silicon using the apparatus shown in FIG. The horizontal reaction column 5 has a diameter of 80 mm at the entrance, a diameter of 20 mm at the connection with the cyclone vertical separation column 9, and its length is 800 mm. The vertical separation tower 9 has a maximum diameter of 120 mm and a height of 600 mm. The molten zinc was poured into the zinc evaporating part from the zinc dissolving part at a rate of 1 kg per hour to evaporate, and the temperature was adjusted to 1250 ° C. in the zinc heating part, and blown into the reaction tower set at 1100 ° C. The gasification part of zinc is preferably made of quartz glass, so that pure zinc gas can be generated. The silicon tetrachloride holding tank was kept at 0 ° C., and the liquid contact surface was pumped to the supply nozzle at a rate of 1.2 kg per hour with a diaphragm type metering pump made of fluororesin. The generated silicon moves in the horizontal reaction tower toward the vertical separation tower, and agglomerates and grows crystallites in the gas to form relatively large particles and fibers. This is advantageous for the separation of silicon and reactive gases.

  Inside the vertical separation tower, the temperature inside the vertical separation tower was set to 1000 ° C. so that everything except silicon was in a gas phase. The silicon holding tank portion is held at 1500 ° C. to melt the separated and accumulated silicon. In this embodiment, a cyclone type silicon and reaction gas separation mechanism is employed. However, a configuration is provided in which a baffle plate is provided at a portion where gas flows from the horizontal reaction column to the vertical separation column, the gas flow collides with this, and the solid silicon is separated and dropped downward. Is also possible. It is also possible to heat the baffle plate above the melting point of silicon and continuously melt the colliding silicon.

  The exhaust gas is connected to a stainless steel drum that has been purged with argon to prevent the inflow of air, cooled, and collected as a liquid or solid. As a result, the exhaust gas composed of zinc and zinc chloride is liquefied and then solidified, resulting in a volume reduction, thereby creating a pressure difference with the gas supply side, which contributes to the driving force of the gas flow in the system.

  When this apparatus was actually operated, 6-nine silicon was obtained as a melt with a yield of 90% or more. Further, when the temperature of the horizontal reaction tower was lowered to about 1050 ° C., the silicon crystal produced in the horizontal reaction tower was increased, but the purity of the produced silicon was slightly improved.

An attempt was made to manufacture silicon using the silicon manufacturing apparatus shown in FIG. 4 according to the present invention. This apparatus has a configuration in which the reduction reaction section 16 and the cyclone separation section 17 of the vertical reaction tower 15 are integrated, and is made of quartz glass. The total height is 900 mm, and the height of the reaction part into which the raw material gas is introduced is 300 mm. The reaction part has a diameter of 60 mm. The temperature of the reaction part was set to 1200 ° C., and the upper set temperature was set to 1050 ° C. to try to manufacture silicon. The amounts of zinc and silicon tetrachloride are both 50% of Example 1. The silicon yield of this apparatus was 95 to 96%, and silicon having a purity of 6 or more was obtained. In addition, even in an apparatus in which silicon tetrachloride is blown in the circumferential direction in accordance with the swirling flow of zinc as shown in FIG. .

  The present invention relates to an apparatus for producing silicon raw material, which is indispensable for the production of silicon solar cells that are expected to expand rapidly over the long term in the future. This technology brings energy savings and productivity improvements. Silicon manufactured by the silicon manufacturing apparatus according to the present invention is used not only as a raw material for a silicon solar cell single crystal substrate and a polycrystalline substrate, but also for an electronic device capable of using a relatively low purity substrate such as an IC tag. However, it is expected to be used greatly. As described above, the technique of the present invention is widely used in the high-purity silicon manufacturing industry and can be expected to greatly contribute to its development.

It is a schematic diagram of the manufacturing apparatus of the silicon | silicone which combined the horizontal reaction tower and vertical separation tower concerning this invention. It is a schematic diagram of the silicon manufacturing apparatus using the vertical reaction tower concerning the present invention. It is a schematic diagram of the manufacturing apparatus of the silicon | silicone which combined the horizontal reaction tower and vertical separation tower concerning this invention. It is a schematic diagram of the silicon manufacturing apparatus using the vertical reaction tower concerning the present invention. It is a schematic diagram of the silicon manufacturing apparatus using the vertical reaction tower concerning the present invention.

Explanation of symbols

1. 1. Zinc melting part 2. Zinc evaporation part 3. Zinc gas heating unit 4. Zinc supply nozzle 5. Horizontal reaction tower 6. Silicon tetrachloride holding part 7. Liquid feed pump 8. Silicon tetrachloride supply nozzle Vertical separation tower 10. Separation gas outlet 11. Separation gas processing device 12. Silicon melting holding tank 13. Partition with bottom penetrated 14. Molten silicon 15 Vertical reactor 16. Reaction section 17. Separation part

Claims (10)

Zinc gas or a zinc mixed gas mainly composed of zinc gas is steadily sent, and silicon tetrachloride is introduced in a liquid state into a reaction tower having a zinc gas atmosphere to cause a zinc reduction reaction. The high-purity silicon production apparatus is characterized in that the silicon produced in (1) is discharged at the terminal end of the reaction tower only from the reaction product gas to the outside of the reaction tower, and the produced silicon is accumulated locally in the reaction tower. 2. The high purity silicon production apparatus according to claim 1, wherein a silicon tetrachloride introduction pipe is provided in the reaction tower according to claim 1 and silicon tetrachloride is discharged into the reaction tower in a mist form. 2. The silicon tetrachloride introduction pipe is provided in the reaction tower according to claim 1, and liquid silicon tetrachloride is discharged from the tip in the form of droplets and dropped in the reaction tower. High purity silicon production equipment. The portion of the reaction tower in which the zinc reduction reaction occurs is a horizontal reaction tower in which a zinc mixed gas and a reaction product gas flow in a lateral direction, and transports silicon produced by the zinc reduction reaction together with the reaction product gas. 4. The high purity according to claim 1, wherein the product is led to a vertical separation column connected to the horizontal reaction column, and the reaction product gas and the generated silicon are separated in the vertical separation column. Silicon manufacturing equipment. The vertical separation tower according to claim 4, which is a cyclone separator, separates generated silicon and reaction product gas, discharges reaction product gas upward or downward, and generates generated silicon downward. The high-purity silicon manufacturing apparatus according to claim 4, wherein the high-purity silicon manufacturing apparatus stores the high-purity silicon. The part where the zinc reduction reaction occurs in the reaction tower according to claim 1 is a vertical reaction tower in which the zinc mixed gas is introduced into a swirling flow, and silicon tetrachloride introduced into the swirling flow in a liquid state The silicon produced by the zinc reduction reaction is separated from the reaction product gas and the produced silicon by a cyclone separator directly connected to the vertical reaction tower, and the reaction product gas is discharged upward or downward. The high-purity silicon manufacturing apparatus according to any one of claims 1 to 3. The high purity according to any one of claims 1 to 6, wherein a portion for locally accumulating the produced silicon in the reaction tower is a silicon melting and holding tank and is held at a temperature equal to or higher than a melting temperature of silicon. Silicon manufacturing equipment. 8. The high-purity silicon production apparatus according to claim 7, wherein the wall surface portion of the silicon melt holding tank according to claim 7 is lower than the silicon melting temperature, and the other region is held at a temperature equal to or higher than the silicon melting temperature. 9. The high purity silicon production apparatus according to claim 1, wherein the temperature of the zinc mixed gas according to claim 1 is 1000 ° C. to 1350 ° C. 9. The high purity silicon production apparatus according to claim 1, wherein the zinc mixed gas according to claim 1 is a mixed gas of zinc gas and zinc chloride gas.

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