WO2011071030A1 - Method for producing polycrystalline silicon, and reactor for producing polycrystalline silicon - Google Patents
Method for producing polycrystalline silicon, and reactor for producing polycrystalline silicon Download PDFInfo
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- WO2011071030A1 WO2011071030A1 PCT/JP2010/071869 JP2010071869W WO2011071030A1 WO 2011071030 A1 WO2011071030 A1 WO 2011071030A1 JP 2010071869 W JP2010071869 W JP 2010071869W WO 2011071030 A1 WO2011071030 A1 WO 2011071030A1
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- C—CHEMISTRY; METALLURGY
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- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
- C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
- C01B33/033—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by reduction of silicon halides or halosilanes with a metal or a metallic alloy as the only reducing agents
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- the present invention relates to a method for producing polycrystalline silicon and a reactor for carrying out the method for producing polycrystalline silicon. More specifically, the present invention relates to a method for producing polycrystalline silicon for producing high-purity polycrystalline silicon for solar cells. The present invention relates to a manufacturing method and a reaction furnace for performing the manufacturing method of the polycrystalline silicon.
- 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 11-N (11-N) and is used as semiconductor silicon.
- Silicon for solar cells has also used some of the products manufactured as semiconductor silicon, but 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.
- the purity of the produced polycrystalline silicon is about six-nine (6-N), which is lower than that for 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.
- a method for producing polycrystalline silicon for example, liquid or gaseous silicon tetrachloride is reduced with molten zinc in a reaction vessel, and a mixture containing the produced polycrystalline silicon and zinc chloride is taken out of the reaction vessel, A method for producing polycrystalline silicon (Patent Document 1), containing the mixture in a separation vessel, separating zinc chloride in the mixture, and then collecting polycrystalline silicon from the separation vessel; The liquid or gaseous silicon tetrachloride is reduced with molten zinc, and the mixture containing the produced polycrystalline silicon and zinc chloride is taken out of the reaction vessel, and the zinc chloride in the mixture is separated, A method for producing high-purity silicon for recovering crystalline silicon, wherein the separated zinc chloride is electrolyzed to recover metallic zinc and chlorine, and the recovered metallic zinc is again used as the silicon tetrachloride.
- Patent Document 2 A method for producing high-purity silicon characterized by being used as a reducing agent and synthesizing the recovered chlorine with hydrogen to form hydrogen chloride, which is used for chlorination of metal 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.
- 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.
- 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.
- Patent Document 3 There has been reported a method for producing silicon powder such that the center axis side is lower than the side.
- 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.
- the purity is low and the utility value is poor because the surface area per unit weight is large.
- the shape of the obtained silicon is preferably a needle shape or flake shape having a certain size.
- 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.
- silicone for solar cells which is flake shape is reported (patent document 5).
- a reactor has a tantalum core or a silicon core that can be energized, and by raising the temperature of the core rod above the reaction temperature, needle-like and flaky silicon is placed on the core rod rather than the reactor. To be deposited.
- the generated silicon is deposited on the tantalum core or the silicon core.
- the tantalum core is used, if the silicon deposited from the tantalum core is scraped off after the reaction is completed, Since the strength of the tantalum is very low and brittle, the tantalum core is broken.
- both the core and the precipitate are the same silicon, so there is no boundary between them, and only the precipitate cannot be scraped off from the silicon core, and the deposited silicon must be melted together with the silicon core. There wasn't.
- an object of the present invention is to provide a method for producing polycrystalline silicon and a reaction furnace by a zinc reduction method in which a precipitation rod can be reused.
- silicon carbide rod is a material in which the generated polycrystalline silicon is easy to precipitate and has high strength.
- the production efficiency is high and the precipitation rod can be reused, and the present invention is completed. It came to.
- the present invention (1) is a method for producing polycrystalline silicon by reacting silicon tetrachloride with zinc to produce polycrystalline silicon, supplying silicon tetrachloride vapor and zinc vapor from the upper part of the reactor, A polycrystal characterized in that exhaust gas is discharged from the lower part of the reactor and the resulting polycrystalline silicon is deposited on a silicon carbide rod while reacting silicon tetrachloride vapor with zinc vapor in the reactor.
- a method for producing silicon is provided.
- the silicon carbide rod is a silicon-impregnated silicon carbide rod in which porous silicon carbide is impregnated with silicon, and the mass ratio of silicon carbide: impregnated silicon is 80:20 to 95:
- the method for producing polycrystalline silicon according to (1) is characterized by being 5.
- the present invention (3) is a reaction furnace for producing polycrystalline silicon by reacting silicon tetrachloride and zinc, having a silicon tetrachloride vapor supply pipe and a zinc vapor supply pipe in the upper part and a lower part.
- the present invention provides a reaction furnace for producing polycrystalline silicon, characterized in that a reaction furnace having an exhaust gas discharge pipe and a silicon carbide rod is installed in the reaction furnace.
- the silicon carbide rod is a silicon-impregnated silicon carbide rod in which porous silicon carbide is impregnated with silicon, and the mass ratio of silicon carbide: impregnated silicon is 80:20 to 95:
- the present invention provides a reactor for producing polycrystalline silicon according to (3), wherein the reactor is 5.
- the present invention it is possible to provide a polycrystalline silicon production method and a reaction furnace by a zinc reduction method in which a precipitation rod can be reused.
- a precipitation rod can be reused.
- the deposition of polycrystalline silicon on the deposition rod is promoted, it becomes difficult to deposit the polycrystalline silicon on the side wall of the reaction furnace, so the polycrystalline silicon produced by the zinc reduction method with high production efficiency can be obtained.
- a manufacturing method and a reaction furnace can be provided.
- FIG. 2 is an end view showing a side wall (reactor) and a silicon carbide rod in FIG. 1.
- It is a schematic diagram which shows the example of the installation position and shape of a supply pipe of silicon tetrachloride vapor and a supply pipe of zinc vapor.
- It is a schematic diagram which shows the example of the installation position and shape of a supply pipe of silicon tetrachloride vapor and a supply pipe of zinc vapor.
- FIG. 1 is a schematic end view of an embodiment of a reactor for producing polycrystalline silicon according to the present invention.
- FIG. 2 is an end view showing the side wall (reactor) and the silicon carbide rod in FIG. 1, and is an end view when cut in the horizontal direction.
- FIGS. 3 and 4 are schematic diagrams showing examples of the installation positions and shapes of the supply pipe for silicon tetrachloride vapor and the supply pipe for zinc vapor, and (3-1) and FIG. 4 in FIG. FIG.
- FIG. 3 is a view of the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe as viewed from above, and (3-2) of FIG. 3 is an end view when cut in the vertical direction.
- FIG. 2 for convenience of explanation, only the side wall (reactor) and the silicon carbide rod are shown, and in FIGS. 3 and 4, the side wall (reactor) and silicon tetrachloride vapor supply pipe and Only the zinc vapor supply pipe is described.
- a reaction furnace 20 includes a side wall part 1 having a vertically long cylindrical shape, a lid part 2 (2a, 2b) that closes the upper and lower sides of the side wall part 1, and a heater 5 for heating the reaction furnace 20; It consists of.
- a supply pipe 7 for silicon tetrachloride vapor 9 and a supply pipe 8 for zinc vapor 10 are attached to the upper part of the reaction furnace 20, and a discharge for discharging the exhaust gas 11 is provided at the lower part of the reaction furnace 20.
- a tube 6 is attached.
- a silicon carbide rod 3 is installed in the reaction furnace 20 via a silicon carbide rod fixing member 4.
- the fixing member 4 of the silicon carbide rod is hooked on the inner wall collar portion 12 formed on the inner wall of the side wall portion 1, so that the hydrocarbon rod 3 is placed inside the reaction furnace 20. It is installed to protrude downward.
- the side wall portion 1 and the lid portion 2 are sealed by, for example, sandwiching a sealing material between the respective flange portions and bolting the flange portions together.
- One end of the silicon tetrachloride vapor supply pipe 7 is located inside the reaction furnace 20, and the other end is connected to a silicon tetrachloride evaporator.
- One end of the zinc vapor supply pipe 8 is located inside the reaction furnace 20, and the other end is connected to a zinc evaporator.
- the exhaust pipe 6 serves as a recovery device for recovering the exhaust gas 11, that is, the zinc chloride gas generated when silicon tetrachloride and zinc react and the silicon tetrachloride vapor and zinc vapor which are unreacted gases. It is connected.
- a method for producing polycrystalline silicon using the reactor 20 will be described.
- silicon tetrachloride and zinc are vaporized by respective evaporators, and silicon tetrachloride vapor 9 is heated from the silicon tetrachloride vapor supply pipe 7 and zinc vapor 10 is heated from the zinc vapor supply pipe 8 by the heater 5.
- the exhaust gas 11 is discharged from the discharge pipe 6 to the outside of the reaction furnace 20 while being supplied into the reaction furnace 20.
- silicon tetrachloride reacts with zinc in the reaction furnace 20 to produce polycrystalline silicon.
- the silicon carbide rod 3 is installed in the reaction furnace 20, it is produced. Polycrystalline silicon is deposited on the silicon carbide rod 3.
- silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the reaction furnace 20 and the exhaust gas 11 is discharged from the lower part of the reaction furnace 20, the silicon tetrachloride vapor and the zinc vapor are Since the silicon carbide rod 3 is moving downward from the top of 20 and along the flow, a polycrystalline silicon crystal grows so as to cover the silicon carbide rod 3. Further, zinc chloride is also generated by the reaction of silicon tetrachloride and zinc, but the zinc chloride gas is discharged out of the exhaust pipe 6 as an exhaust gas 11 together with unreacted silicon tetrachloride vapor and zinc vapor. .
- the reactor for producing polycrystalline silicon according to the present invention is a reactor for reacting silicon tetrachloride with zinc to produce polycrystalline silicon, and has a silicon tetrachloride vapor supply pipe and a zinc vapor supply at the top.
- a reaction furnace for producing polycrystalline silicon characterized in that the reaction furnace has a pipe and an exhaust gas discharge pipe at the bottom, and a silicon carbide rod is installed in the reaction furnace.
- examples of the material of the reaction furnace include quartz such as transparent quartz, opaque quartz, and sintered quartz, silicon carbide, silicon nitride, etc. Of these, silicon carbide and silicon nitride are preferable, and quartz and silicon nitride are preferable from the viewpoint that cracks due to a temperature gradient are unlikely to occur. Further, depending on the structure of the reaction furnace and the like, the material of the reaction furnace is not particularly limited as long as it can withstand the heating temperature during the reaction. Further, the side wall portion and the lid portion of the reactor may be made of different materials.
- the shape of the 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, that is, It is a vertically long shape.
- the shape of the reaction furnace is such that the raw material vapor and the exhaust gas flow from the upper part to the lower part of the reaction furnace.
- the size of the reactor is not particularly limited, but is appropriately selected depending on the supply conditions of silicon tetrachloride vapor and zinc vapor.
- the length of the reactor in the longitudinal direction is 1,000 to 6,000 mm, and in the case of a cylindrical shape, the diameter is 200 to 2,000 mm.
- the silicon carbide rod is installed in the reactor.
- a prismatic shape and a cylindrical shape are preferable, and a cylindrical shape is particularly preferable.
- the diameter of the silicon carbide rod is preferably 1 to 20 cm, and particularly preferably 2 to 10 cm, from the viewpoint of strength and processing surface.
- the length of the silicon carbide rod existing between the lower side of the fixing member 4 of the silicon carbide rod and the upper side of the discharge pipe 6 is from the lower side of the fixing member 4 to the upper side of the discharge pipe 6. 5 to 120% is preferable with respect to the length in the vertical direction, 20 to 100% is particularly preferable, and 40 to 90% is more preferable.
- the silicon carbide rod is a silicon carbide molded body, but usually the silicon carbide molded body is a porous body having a large number of pores.
- the silicon carbide rod is a silicon-impregnated silicon carbide rod in which silicon is impregnated with porous silicon carbide, and the impregnated silicon becomes a seed of polycrystalline silicon crystals produced by the reaction, This is preferable in that the precipitation of polycrystalline silicon on the silicon carbide rod can be promoted.
- 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.
- a porous silicon carbide rod not impregnated with silicon is installed in the reactor and a reaction between silicon tetrachloride vapor and zinc vapor is performed, carbonization is performed at an early stage of the reaction.
- the silicon carbide rod In the porous structure near the outside of the silicon rod, contact between the silicon tetrachloride vapor and the zinc vapor occurs, and silicon is generated there, so the silicon carbide rod is impregnated in the vicinity of the outside of the silicon carbide rod. It becomes the same state as. Therefore, a porous silicon carbide rod not impregnated with silicon may be used.
- a porous silicon carbide rod not impregnated with silicon is used by repeated use. It becomes the state similar to the porous silicon carbide rod impregnated with.
- the number of silicon carbide rods installed may be one or two or more.
- the installation position of the silicon carbide rod is not particularly limited.
- the silicon carbide rods 3 are installed at equal intervals on an arc centered on the center of the side wall 1 (reactor). It is preferable.
- the number and position of the silicon carbide rods to be installed are appropriately selected so that the polycrystalline silicon is efficiently precipitated depending on the reaction conditions such as the supply conditions of the raw material vapor and the size of the reaction furnace.
- the silicon carbide rod 3 is fixed to the silicon carbide rod fixing member 4, and the silicon carbide rod fixing member 4 is attached to the furnace inner wall collar portion 12.
- the present invention is not limited to this.
- a furnace inner wall collar portion is formed below the attachment position of the discharge pipe 6, and the silicon carbide rod fixing member to which the silicon carbide rod is fixed is hooked on the furnace wall collar portion.
- a heater for heating may be provided inside the silicon carbide rod.
- the silicon carbide rod is set to 1,000 ° C., so that polycrystalline silicon is selectively deposited by the silicon carbide rod.
- silicon carbide is a material having high thermal conductivity and receiving a large amount of radiant heat, it receives a lot of radiant heat from the side wall of the reactor, and the carbonization can be selectively performed to some extent without heating the silicon carbide rod. It is possible to deposit polycrystalline silicon on the silicon rod.
- the supply pipe for the silicon tetrachloride vapor and the supply pipe for the zinc vapor are attached to the top of the reaction furnace.
- the discharge pipe is attached to the lower part of the reactor.
- a downward flow of the raw material vapor is formed in the reactor, and a position (vertical direction position) at which the reaction between silicon tetrachloride and zinc can be caused in the reactor.
- the silicon tetrachloride vapor supply pipe, the zinc vapor supply pipe, and the discharge pipe are attached.
- the shape and arrangement of the silicon tetrachloride vapor supply pipe and the zinc vapor supply pipe for example, as shown in FIG. 3 (3-1), the silicon tetrachloride vapor supply pipe and the zinc vapor
- the horizontal portion of the supply pipe is arranged in a straight line, and as shown in (3-2), the tip of the supply pipe is L-shaped and the outlet of the supply pipe faces downward.
- steam on a straight line is mentioned.
- a heater is installed around the side wall of the reactor.
- the heater is preferably an electric heater.
- the method for producing polycrystalline silicon of the present invention is a method for producing polycrystalline silicon by reacting silicon tetrachloride with zinc to supply silicon tetrachloride vapor and zinc vapor from the upper part of the reactor.
- the exhaust gas is discharged from the lower part of the reaction furnace, and the generated polycrystalline silicon is deposited on the silicon carbide rod while reacting the silicon tetrachloride vapor and the zinc vapor in the reaction furnace. This is a method for producing polycrystalline silicon.
- Examples of the reactor for carrying out the method for producing polycrystalline silicon of the present invention include the reactor for producing polycrystalline silicon of the present invention.
- the silicon tetrachloride vapor and the zinc vapor may be diluted with an inert gas such as nitrogen gas.
- the dilution rate of the silicon tetrachloride vapor is a volume ratio ((silicon tetrachloride vapor + inert gas).
- the boiling point of zinc is 907 ° C. Therefore, the reactor is heated so that the temperature in the reactor becomes 907 ° C., which is the boiling point of zinc. .
- the temperature in the reactor is 907 to 1,200 ° C., preferably 930 to 1,100 ° C.
- the pressure in the reaction furnace is preferably 0 to 700 kPaG, particularly preferably 0 to 500 kPaG.
- the silicon carbide rod according to the method for producing polycrystalline silicon of the present invention is the same as the silicon carbide rod according to the reaction furnace for producing polycrystalline silicon according to the present invention.
- the silicon carbide rod may be heated by using one or two or more silicon carbide rods with a built-in heater. At that time, all of the silicon carbide rods installed in the reaction furnace may be heated, or a part thereof may be heated.
- the heating start time of the silicon carbide rod may be before the polycrystalline silicon starts to be deposited on the silicon carbide rod, that is, before the supply of silicon tetrachloride vapor and zinc vapor, or the carbonization of the silicon carbide rod. It may be after a certain amount of polycrystalline silicon is deposited on the silicon rod.
- silicon tetrachloride vapor and zinc vapor are moved downward, the silicon tetrachloride reacts with zinc in the reactor, and polycrystalline silicon is generated,
- silicon carbide rod By allowing the silicon carbide rod to exist along the flow of silicon tetrachloride vapor and zinc vapor, polycrystalline silicon is deposited on the silicon carbide rod.
- an inert gas supply pipe such as nitrogen gas is attached to the reaction furnace, the inert gas is introduced into the reaction furnace, and the interior of the reaction furnace is inactivated. It can be pressurized with an active gas.
- the production of polycrystalline silicon is completed by stopping the supply of silicon tetrachloride vapor and zinc vapor. Thereafter, the reactor is cooled, and the silicon carbide rod on which polycrystalline silicon is deposited is taken out of the reactor. Then, the deposited polycrystalline silicon is scraped off from the silicon carbide rod to obtain polycrystalline silicon. If polycrystalline silicon is deposited on the furnace wall of the reactor, it is also scraped off and collected.
- the silicon carbide rod after scraping the polycrystalline silicon is again used in the method for producing polycrystalline silicon of the present invention. Further, before reuse, the silicon carbide rod may be washed with pure water or an acid such as hydrochloric acid, nitric acid, hydrofluoric acid or the like.
- 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 0.1 to 100 ppm by mass, preferably 0.1 to 10 ppm by mass, particularly preferably 0.1 to 1 ppm by mass. It is.
- a high-purity polycrystalline silicon ingot of 6-N or more can be produced.
- the analysis of the purity of the polycrystalline silicon is obtained by high frequency induction plasma emission analysis (ICP-AES). The analysis method is as follows.
- the main shape of the polycrystalline silicon obtained by the method for producing polycrystalline silicon of the present invention is a dendritic shape, a needle shape or a plate shape, and is not a fine particle having a diameter of 3 ⁇ m or less.
- the silicon crystal grows in a dendritic or needle shape, so that it grows into a large dendritic or needle shape.
- the needle-like ones there are also those that become plate-like, small dendrites or needle-like ones, and when scraping from the silicon carbide rod, the dendrites or needle-like ones break down and small dendrites Some of them are shaped like needles or needles.
- the size of the dendritic, needle-like or plate-like polycrystalline silicon is preferably 100 ⁇ m or more, particularly preferably 500 ⁇ m or more, and further preferably 1,000 ⁇ m or more.
- the dendritic, needle-like or plate-like polycrystalline silicon is preferably dendritic, needle-like or plate-like polycrystalline silicon in which 50% by mass or more does not pass through a screen of 100 ⁇ m mesh size.
- Particularly preferred is a dendritic, needle-like or plate-like polycrystalline silicon whose mass% or more does not pass through a screen of 500 ⁇ m mesh size.
- the dendritic shape is a shape composed of a trunk portion 31 and a branch portion 32 extending from the trunk portion 31 as shown in FIG. 5 (5-1).
- the shape extends in a substantially straight line
- the plate shape is a shape that extends in a substantially planar direction such as a scale shape or a flake shape.
- the branches extend further from the dendritic branch 32 and the crystal extends.
- the size of the dendritic, needle-like or plate-like polycrystalline silicon is the length of the longest part of the crystal in the case of a dendritic shape (the length of 33a in FIG. 5 (5-1)).
- a needle shape indicates the length of the crystal (the length of reference numeral 33b in (5-2) of FIG. 5), and in the case of a plate shape, it indicates the longest diameter of the crystal.
- silicon carbide is a hard material, when the polycrystalline silicon is scraped off from the silicon carbide rod after the manufacturing process is finished, the silicon carbide rod is not broken. Therefore, the silicon carbide rod can be reused.
- silicon carbide has an expansion coefficient close to that of silicon, the silicon carbide rod is unlikely to be broken due to a difference in shrinkage when cooled after the reaction is completed.
- the presence of the silicon carbide rod promotes the precipitation to the silicon carbide rod, so the yield of polycrystalline silicon is increased, and the deposition of silicon on the side walls of the reactor is suppressed, and the manufacturing process Since the operation of removing the polycrystalline silicon deposited on the furnace wall after the process is reduced, the manufacturing efficiency is increased.
- silicon carbide is a black or dark green material, it easily absorbs radiant heat in the reaction furnace, and the yield of polycrystalline silicon is increased.
- Example 1 In the following reactor, zinc vapor heated and vaporized from a zinc vapor supply pipe to 930 ° C. was introduced into the reaction furnace together with nitrogen gas, and vaporized by heating to 930 ° C. from a silicon tetrachloride vapor supply pipe. While supplying silicon tetrachloride vapor to the reactor, the inside of the reactor was set to 930 ° C., the heating temperature of the silicon carbide rod was set to 1,000 ° C., silicon tetrachloride was transferred at a rate of 74 g / min, and zinc was added at 50 g / min. Feeding at a rate, the reaction between silicon tetrachloride and zinc was carried out.
- Reactor (in the embodiment shown in FIG. 1, the number of silicon carbide rods installed is 3)> Reactor: Uses a quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm Silicon carbide rod: Outer diameter of 30 mm x length of 1,000 mm, 3 pieces (equally spaced on an arc centered on the center of the reaction furnace) ), Porosity 5% Positional relationship between silicon tetrachloride vapor supply pipe and zinc vapor supply pipe in the vertical direction: the same height Positional relationship between silicon tetrachloride vapor supply pipe and zinc vapor supply pipe in the horizontal direction: Positional relationship shown in Fig.
- Example 2 The same procedure as in Example 1 was performed except that a silicon-impregnated silicon carbide rod was used.
- the mass ratio of silicon carbide: impregnated silicon of the silicon-impregnated silicon carbide rod was 85:15.
- Example 1 The same procedure as in Example 1 was performed except that a tantalum rod was used instead of the silicon carbide rod. After reacting for 40 hours, it was cooled and the tantalum rod was taken out of the reactor. Next, polycrystalline silicon was scraped off from the tantalum rod to obtain polycrystalline silicon. The yield of polycrystalline silicon was 62% with respect to the feedstock, and the purity of polycrystalline silicon was 6-N. Further, almost no silicon deposition was observed on the side wall of the reactor. The tantalum rod was destroyed when the polycrystalline silicon was scraped off.
- polycrystalline silicon can be produced at low cost.
- the precipitation of polycrystalline silicon is promoted by the silicon carbide rod, polycrystalline silicon can be produced efficiently.
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Abstract
Description
SiCl4 + 2Zn = Si + 2ZnCl2 (1)
により示すものである。 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.
また、本発明(2)は、前記炭化珪素棒は、多孔質の炭化珪素にシリコンが含浸されているシリコン含浸炭化珪素棒であり、炭化珪素:含浸シリコンの質量比が80:20~95:5であることを特徴とする(1)の多結晶シリコンの製造方法を提供するものである。 That is, the present invention (1) is a method for producing polycrystalline silicon by reacting silicon tetrachloride with zinc to produce polycrystalline silicon, supplying silicon tetrachloride vapor and zinc vapor from the upper part of the reactor, A polycrystal characterized in that exhaust gas is discharged from the lower part of the reactor and the resulting polycrystalline silicon is deposited on a silicon carbide rod while reacting silicon tetrachloride vapor with zinc vapor in the reactor. A method for producing silicon is provided.
In the present invention (2), the silicon carbide rod is a silicon-impregnated silicon carbide rod in which porous silicon carbide is impregnated with silicon, and the mass ratio of silicon carbide: impregnated silicon is 80:20 to 95: The method for producing polycrystalline silicon according to (1) is characterized by being 5.
また、本発明(4)は、前記炭化珪素棒は、多孔質の炭化珪素にシリコンが含浸されているシリコン含浸炭化珪素棒であり、炭化珪素:含浸シリコンの質量比が80:20~95:5であることを特徴とする(3)の多結晶シリコン製造用の反応炉を提供するものである。 Further, the present invention (3) is a reaction furnace for producing polycrystalline silicon by reacting silicon tetrachloride and zinc, having a silicon tetrachloride vapor supply pipe and a zinc vapor supply pipe in the upper part and a lower part. The present invention provides a reaction furnace for producing polycrystalline silicon, characterized in that a reaction furnace having an exhaust gas discharge pipe and a silicon carbide rod is installed in the reaction furnace.
In the present invention (4), the silicon carbide rod is a silicon-impregnated silicon carbide rod in which porous silicon carbide is impregnated with silicon, and the mass ratio of silicon carbide: impregnated silicon is 80:20 to 95: The present invention provides a reactor for producing polycrystalline silicon according to (3), wherein the reactor is 5.
得られた多結晶シリコン1.5gに、38%フッ化水素酸16mlと55%硝酸30mlを加えて、完全に溶解させた後、蒸発乾固させる。次いで、1%硝酸5mlで定溶し、ICP-AES(サーモフィッシャーサイエンティフィック株式会社製IRIS Advantage/RP型)により不純物濃度を測定して、多結晶シリコンの純度を算出する。 Thus, 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 0.1 to 100 ppm by mass, preferably 0.1 to 10 ppm by mass, particularly preferably 0.1 to 1 ppm by mass. It is. When the zinc content in the polycrystalline silicon is within the above range, a high-purity polycrystalline silicon ingot of 6-N or more can be produced. The analysis of the purity of the polycrystalline silicon is obtained by high frequency induction plasma emission analysis (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.
下記反応炉において、亜鉛蒸気の供給管から930℃に加熱して気化させた亜鉛蒸気を窒素ガスと共に反応炉内に導入し、四塩化珪素蒸気の供給管から930℃に加熱して気化させた四塩化珪素蒸気を反応炉に供給しつつ、反応炉内を930℃、炭化珪素棒の加熱温度を1,000℃にして、四塩化珪素を74g/分の速度で、亜鉛を50g/分の速度で供給し、四塩化珪素と亜鉛の反応を行った。
<反応炉(図1の形態例で、炭化珪素棒の設置本数が3本の形態例)>
反応炉:内径300mm×長さ2,500mmの石英製反応管を使用
炭化珪素棒:外径30mm×長さ1,000mm、本数3本(反応炉の中心を中心とする円弧上に、等間隔に設置)、気孔率5%
四塩化珪素蒸気供給管と亜鉛蒸気供給管の垂直方向の位置関係:同一高さ
四塩化珪素蒸気供給管と亜鉛蒸気供給管の水平方向の位置関係:図4に示す位置関係
反応炉出口の排出管内径:100mm
排出管の位置:排出管6の下側が反応炉の下側の蓋部2bの上面より700mm上側
固定部材4の下側から排出管6の上側の間に存在する炭化珪素棒の長さ:固定部材4の下側から排出管6の上側までの長さの90% Example 1
In the following reactor, zinc vapor heated and vaporized from a zinc vapor supply pipe to 930 ° C. was introduced into the reaction furnace together with nitrogen gas, and vaporized by heating to 930 ° C. from a silicon tetrachloride vapor supply pipe. While supplying silicon tetrachloride vapor to the reactor, the inside of the reactor was set to 930 ° C., the heating temperature of the silicon carbide rod was set to 1,000 ° C., silicon tetrachloride was transferred at a rate of 74 g / min, and zinc was added at 50 g / min. Feeding at a rate, the reaction between silicon tetrachloride and zinc was carried out.
<Reactor (in the embodiment shown in FIG. 1, the number of silicon carbide rods installed is 3)>
Reactor: Uses a quartz reaction tube with an inner diameter of 300 mm x length of 2500 mm Silicon carbide rod: Outer diameter of 30 mm x length of 1,000 mm, 3 pieces (equally spaced on an arc centered on the center of the reaction furnace) ),
Positional relationship between silicon tetrachloride vapor supply pipe and zinc vapor supply pipe in the vertical direction: the same height Positional relationship between silicon tetrachloride vapor supply pipe and zinc vapor supply pipe in the horizontal direction: Positional relationship shown in Fig. 4 Discharge at reactor outlet Pipe inner diameter: 100mm
The position of the discharge pipe: the lower side of the discharge pipe 6 is 700 mm above the upper surface of the
シリコン含浸炭化珪素棒を用いたこと以外は、実施例1と同様に行った。なお、シリコン含浸炭化珪素棒の炭化珪素:含浸シリコンの質量比は、85:15であった。 (Example 2)
The same procedure as in Example 1 was performed except that a silicon-impregnated silicon carbide rod was used. The mass ratio of silicon carbide: impregnated silicon of the silicon-impregnated silicon carbide rod was 85:15.
炭化珪素棒に代えて、タンタル棒を用いた以外は、実施例1と同様に行った。
40時間反応を行った後、冷却し、タンタル棒を反応炉の外に取り出した。次いで、タンタル棒から多結晶シリコンを掻き落して、多結晶シリコンを得た。多結晶シリコンの収率は、供給原料に対し62%であり、多結晶シリコンの純度は6-Nであった。また、反応炉の側壁には、ほとんど、シリコンの析出は観察されなかった。なお、タンタル棒は、多結晶シリコンを掻き落す際に、破壊されてしまった。 (Comparative Example 1)
The same procedure as in Example 1 was performed except that a tantalum rod was used instead of the silicon carbide rod.
After reacting for 40 hours, it was cooled and the tantalum rod was taken out of the reactor. Next, polycrystalline silicon was scraped off from the tantalum rod to obtain polycrystalline silicon. The yield of polycrystalline silicon was 62% with respect to the feedstock, and the purity of polycrystalline silicon was 6-N. Further, almost no silicon deposition was observed on the side wall of the reactor. The tantalum rod was destroyed when the polycrystalline silicon was scraped off.
2、2a、2b 蓋部
3 炭化珪素棒
4 炭化珪素棒の固定部材
5 ヒーター
6 排出管
7 四塩化珪素蒸気の供給管
8 亜鉛蒸気の供給管
9 四塩化珪素蒸気
10 亜鉛蒸気
11 排出ガス
12 炉内壁つば部
20 反応炉
31 幹部
32 枝部 DESCRIPTION OF
Claims (4)
- 四塩化珪素と亜鉛を反応させて多結晶シリコンを生成させる多結晶シリコンの製造方法であって、四塩化珪素蒸気及び亜鉛蒸気を反応炉の上部から供給し、該反応炉の下部から排出ガスを排出して、該反応炉内で四塩化珪素蒸気と亜鉛蒸気の反応を行いつつ、生成する多結晶シリコンを炭化珪素棒に析出させることを特徴とする多結晶シリコンの製造方法。 A method for producing polycrystalline silicon by reacting silicon tetrachloride with zinc to produce polycrystalline silicon, wherein silicon tetrachloride vapor and zinc vapor are supplied from the upper part of the reactor, and exhaust gas is emitted from the lower part of the reactor. A method for producing polycrystalline silicon, comprising discharging and depositing polycrystalline silicon to be produced on a silicon carbide rod while reacting silicon tetrachloride vapor and zinc vapor in the reactor.
- 前記炭化珪素棒は、多孔質の炭化珪素にシリコンが含浸されているシリコン含浸炭化珪素棒であり、炭化珪素:含浸シリコンの質量比が80:20~95:5であることを特徴とする請求項1記載の多結晶シリコンの製造方法。 The silicon carbide rod is a silicon-impregnated silicon carbide rod in which silicon is impregnated with porous silicon carbide, and a mass ratio of silicon carbide: impregnated silicon is 80:20 to 95: 5. Item 2. A method for producing polycrystalline silicon according to Item 1.
- 四塩化珪素と亜鉛を反応させて多結晶シリコンを生成させる反応炉であって、上部に四塩化珪素蒸気の供給管及び亜鉛蒸気の供給管を有し且つ下部に排出ガスの排出管を有する反応炉であり、炭化珪素棒が該反応炉内に設置されていることを特徴とする多結晶シリコン製造用の反応炉。 A reaction furnace in which silicon tetrachloride and zinc are reacted to produce polycrystalline silicon, a reaction having 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 reactor for producing polycrystalline silicon, characterized in that a silicon carbide rod is installed in the reactor.
- 前記炭化珪素棒は、多孔質の炭化珪素にシリコンが含浸されているシリコン含浸炭化珪素棒であり、炭化珪素:含浸シリコンの質量比が80:20~95:5であることを特徴とする請求項3記載の多結晶シリコン製造用の反応炉。 The silicon carbide rod is a silicon-impregnated silicon carbide rod in which silicon is impregnated with porous silicon carbide, and a mass ratio of silicon carbide: impregnated silicon is 80:20 to 95: 5. Item 4. A reactor for producing polycrystalline silicon according to Item 3.
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JP2004018370A (en) * | 2002-06-19 | 2004-01-22 | Yutaka Kamaike | Apparatus and method of manufacturing silicon |
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JP2009208995A (en) * | 2008-03-04 | 2009-09-17 | Sumitomo Chemical Co Ltd | Manufacturing apparatus for silicon |
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JP2004018370A (en) * | 2002-06-19 | 2004-01-22 | Yutaka Kamaike | Apparatus and method of manufacturing silicon |
JP2007112691A (en) * | 2005-10-21 | 2007-05-10 | Yutaka Kamaike | Apparatus and method for producing silicon |
JP2009208995A (en) * | 2008-03-04 | 2009-09-17 | Sumitomo Chemical Co Ltd | Manufacturing apparatus for silicon |
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