Apparatus and Method for Manufacturing Polysilicon and Polysilicon

Abstract

The present invention reduces the impurity concentration of polycrystalline silicon to be manufactured. A polycrystalline silicon (S1) manufacturing device (1) comprises: a reactor (10), the reactor (10) containing a raw material gas (G1) for silicon precipitation; a supply pipe (20), the supply pipe (20) forming a supply flow channel, the supply flow channel including an inlet (111) formed in the reactor (10) for flowing the raw material gas (G1), the supply flow channel being used to supply the raw material gas (G1) into the reactor (10); and a filter (30), the filter (30) being arranged in the supply flow channel and removing impurities mixed in the raw material gas (G1).

Description

Technical Field

[0001] The present invention relates to a polysilicon manufacturing device, a polysilicon manufacturing method and polysilicon. Background Art

[0002] The Siemens process is a well-known method for producing polycrystalline silicon, used as a raw material for semiconductors and solar power generation wafers. In the Siemens process, a silicon core wire placed inside a bell-jar reactor is first heated to a silicon precipitation temperature by applying electricity. In this state, trichlorosilane (SiHCl3) and hydrogen (H2) are supplied into the reactor, causing polycrystalline silicon to precipitate on the silicon core wire, resulting in rod-shaped polycrystalline silicon.

[0003] Patent Document 1 discloses a reactor comprising an air intake system and an exhaust system, each of which has openings or a mesh and at least one protective element. The protective element is provided to prevent polysilicon fragments from falling into the air intake and exhaust openings and clogging the gas conduit or gas distribution device.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application No. 2018-530511 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, impurities from materials used in piping, etc., may sometimes adhere to the supply flow path for supplying the raw material gas into the reactor. When the raw material gas is supplied to the reactor, these impurities scatter within the reactor and adhere to the precipitating polycrystalline silicon, thereby increasing the impurity concentration of the produced polycrystalline silicon.

[0009] Impurities are very small, making it difficult to prevent contamination by them using the protective elements disclosed in Patent Document 1. Consequently, the prior art disclosed in Patent Document 1 suffers from the problem of increased impurity concentration in the produced polycrystalline silicon. One aspect of the present invention aims to reduce the impurity concentration in the produced polycrystalline silicon.

[0010] Means of solving the problem

[0011] In order to solve the above-mentioned problem, a polysilicon manufacturing device involved in one form of the present invention comprises: a reactor, which accommodates raw material gas for silicon precipitation; a piping, which forms a supply flow channel, the supply flow channel includes an inlet through which the raw material gas flows and is formed in the reactor, and the supply flow channel is used to supply the raw material gas into the reactor; and a filter, which is arranged in the supply flow channel and removes impurities mixed in the raw material gas.

[0012] A method for manufacturing polycrystalline silicon according to one embodiment of the present invention includes: an impurity removal step, wherein a filter is provided in a supply flow path for supplying a raw material gas into a reactor containing the raw material gas for silicon precipitation, and impurities mixed in the raw material gas are removed by the filter; and a silicon precipitation step, wherein polycrystalline silicon is precipitated by supplying the raw material gas from which the impurities have been removed in the impurity removal step into the reactor.

[0013] Effects of the Invention

[0014] According to one aspect of the present invention, the impurity concentration of polycrystalline silicon to be produced can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram showing a polycrystalline silicon manufacturing apparatus according to the first embodiment of the present invention.

[0016] Figure 2 Yes Figure 1 1 is a cross-sectional view showing the structure of a filter included in a polycrystalline silicon manufacturing apparatus.

[0017] Figure 3 This is a diagram showing an example of the configuration of a filter included in the polycrystalline silicon manufacturing apparatus according to the second embodiment of the present invention.

[0018] Figure 4 Yes Figure 3 The filter accuracy of the filter is shown in the diagram.

[0019] Figure 5 This is a diagram showing an example of the configuration of a filter included in the polycrystalline silicon manufacturing apparatus according to the third embodiment of the present invention.

[0020] Figure 6 This is a diagram showing an example of the configuration of a filter included in the polycrystalline silicon manufacturing apparatus according to the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0021] [Implementation Method 1]

[0022] <Configuration of Polycrystalline Silicon S1 Manufacturing Apparatus 1>

[0023] Figure 1 Schematic diagram showing a manufacturing apparatus 1 for polycrystalline silicon S1 according to the first embodiment of the present invention. Figure 1 As shown, a polycrystalline silicon S1 production apparatus 1 includes a reactor 10, a supply pipe 20 (pipe), a filter 30, a supply nozzle 40, an electrode 50, and a discharge pipe 60. The production apparatus 1 may not include the supply nozzle 40.

[0024] The reactor 10 consists of a bottom 11 on which polycrystalline silicon S1 is placed, and a bell-jar-shaped cover 12 detachably connected to the bottom 11. With the cover 12 connected to the bottom 11, the reactor 10 contains a raw material gas G1 for silicon deposition. The raw material gas G1 is a mixed gas of chlorosilanes and hydrogen.

[0025] The bottom portion 11 is formed with an inlet 111 for introducing the raw material gas G1 into the reactor 10, and an outlet 112 for discharging the waste gas HG after the reaction in the reactor 10. The inlet 111 extends through a through hole H1 in the bottom portion 11, and the outlet 112 extends through a through hole H2 in the bottom portion 11. Figure 1 In the embodiment, two inlet ports 111 and one outlet port 112 are formed in the bottom portion 11 , but the number of inlet ports 111 and outlet ports 112 formed in the bottom portion 11 is not particularly limited.

[0026] The supply pipe 20 includes a first pipe 21 and a second pipe 22. One end of the first pipe 21 is connected to a supply unit (not shown) for supplying the raw material gas G1, and the other end is connected to the second pipe 22. The raw material gas G1 can be evenly supplied to each inlet 111. Figure 1 In FIG, the number of the second pipes 22 is two, but since the number is the same as the number of the inlet ports 111 , the number can be appropriately changed according to the number of the inlet ports 111 .

[0027] The second pipe 22 connects the first pipe 21 to the bottom portion 11. The second pipe 22 extends between the connection between the first pipe 21 and the second pipe 22 and the end of the through-hole H1 opposite the inlet 111. Alternatively, the second pipe 22 may extend between the connection between the first pipe 21 and the second pipe 22 and the inlet 111.

[0028] The supply pipe 20 is made of, for example, stainless steel. Stainless steel is an alloy containing at least one of the following elements: Fe, Ni, Cr, Mn, Cu, Ti, Mo, and Nb. The supply pipe 20 is corroded by the raw material gas G1, and impurities containing the stainless steel's constituent elements are mixed into the raw material gas G1. These impurities include oxides and chlorides of the stainless steel's constituent elements.

[0029] Since the supply pipe 20 is made of stainless steel, it is possible to prevent the constituent elements of stainless steel, such as at least one of heavy metal elements such as Fe, Ni, Cr, Mn, Cu, Ti, Mo, and Nb, from penetrating into the reactor 10 .

[0030] The supply flow path for supplying the raw material gas G1 into the reactor 10 is formed by the supply pipe 20, the inlet 111, and the supply nozzle 40. Specifically, the supply flow path includes the inlet 111, and the supply pipe 20 forms the supply flow path. Furthermore, the supply flow path also includes the inlet E1 of the supply nozzle 40, that is, the front end of the supply nozzle 40.

[0031] The supply nozzle 40 is a nozzle that protrudes from the inlet 111 into the reactor 10. The supply nozzle 40 is disposed at the bottom 11 so that the raw material gas G1 flowing from the inlet 111 reaches the upper portion of the reactor 10 and allows the polycrystalline silicon S1 to grow uniformly. Furthermore, the supply nozzle 40 is used to prevent the raw material gas G1 from being directly sprayed near the electrode 50. The supply nozzle 40 prevents the polycrystalline silicon S1 from being easily broken.

[0032] The supply nozzle 40 is preferably made of a material having high corrosion resistance to the raw material gas G1, such as carbon. The supply nozzle 40 has a nozzle shape, but may have other shapes, such as an orifice plate provided at the inlet 111.

[0033] Electrodes 50 are used to supply power to silicon cores (not shown) electrically connected to them, thereby energizing and heating the silicon cores. At least one pair of electrodes 50 is provided on bottom 11. The number of electrodes 50 is determined based on the number of silicon cores installed within reactor 10.

[0034] The exhaust pipe 60 is a pipe for discharging the exhaust gas HG generated in the silicon precipitation step described later to the outside of the reactor 10. The exhaust pipe 60 extends between the outside of the reactor 10 and one end of the through-hole H2 opposite to the exhaust port 112. Alternatively, the exhaust pipe 60 may extend between the outside of the reactor 10 and the exhaust port 112.

[0035] <Configuration of Filter 30>

[0036] The filter 30 is provided in the supply flow channel and is used to remove impurities that have entered the raw material gas G1. Specifically, the filter 30 is provided in any of the supply piping 20, the inlet 111, the supply nozzle 40, and the inlet E1. To minimize the amount of impurities that enter the reactor 10, the filter 30 is preferably provided in the supply flow channel near or within the reactor 10. For example, it is preferably provided at the inlet 111 of the supply flow channel.

[0037] Figure 2 Yes Figure 1 1 is a cross-sectional view showing the structure of the filter 30 included in the manufacturing apparatus 1 for polycrystalline silicon S1. Figure 2 As shown, the filter 30 has a cylindrical shape and includes a first end 31, a second end 32, and a filtering surface 33. The filter 30 has an open first end 31 and a closed second end 32 opposite to the first end 31, and the filtering surface 33 extends between the first end 31 and the second end 32.

[0038] The filter 30 is preferably made of a material with high corrosion resistance to the raw material gas G1. For example, it can be made of stainless steel containing 10% or more Ni, corrosion-resistant materials (such as Hastelloy, Inconel 600, Incoloy 800, and Incoloy 800H), or ceramics (such as alumina, titanium oxide, zirconium oxide, quartz, silicon carbide, silicon nitride, and aluminum nitride). Considering economic efficiency, the filter 30 is preferably made of stainless steel containing 10% or more Ni, and more preferably, it is made of SUS316L.

[0039] The first end 31 is located on the downstream side of the supply flow channel, and the second end 32 is located on the upstream side of the supply flow channel. The filter 30 is configured such that the first end 31 is located on the side opposite to the second end 32. The first end 31 of the filter 30 is fixed to the connecting member CN1 mounted on the inlet 111. The filter 30 is fixed to one end of the connecting member CN1, and the supply nozzle 40 is mounted on the other end of the connecting member CN1. In addition, by removing the connecting member CN1 from the inlet 111, the filter 30 fixed to the connecting member CN1 can be easily cleaned.

[0040] Furthermore, the outer circumference of the first end 31 is fixed to the inner wall of the supply flow path so that the first end 31 and the second end 32 are aligned along the inner wall of the supply flow path. In other words, the outer circumference of the first end 31 is fixed to the inner wall of at least one of the supply pipe 20, the through hole H1 of the bottom 11, and the supply nozzle 40.

[0041] This configuration increases the surface area of the filter 30, thereby reducing the pressure loss of the raw material gas G1 caused by the installation of the filter 30. Furthermore, the raw material gas G1 can be stably supplied without closing the filter 30 until the deposition of the polycrystalline silicon S1 is complete. Consequently, polycrystalline silicon S1 can be efficiently produced.

[0042] Furthermore, the filter surface 33 may be formed of a mesh or a sintered body of fine powder of metal or ceramic, for example. Furthermore, the filter surface 33 may be formed by overlapping a mesh and a sintered body. In this case, the mesh is preferably placed on the outside and the sintered body is placed on the inside.

[0043] As described above, according to the configuration of the manufacturing apparatus 1, impurities mixed in the raw material gas G1 for silicon precipitation can be removed by the filter 30. Therefore, polycrystalline silicon S1 can be manufactured by supplying the raw material gas G1 from which the impurities have been removed into the reactor 10. Therefore, the impurity concentration of the polycrystalline silicon S1 to be manufactured can be reduced.

[0044] <Method for Manufacturing Polycrystalline Silicon S1>

[0045] Next, an example of a method for producing polycrystalline silicon S1 is described. First, impurities mixed into the raw material gas G1 are removed using the filter 30 (impurity removal step). This impurity removal step is preferably performed immediately before the raw material gas G1 is supplied to the reactor 10. This minimizes the amount of impurities that enter the reactor 10.

[0046] After the impurity removal step, the raw material gas G1 from which impurities have been removed is supplied into the reactor 10 to precipitate polycrystalline silicon S1 (silicon precipitation step). In the method for producing polycrystalline silicon S1, the raw material gas G1 is preferably a mixed gas of chlorosilanes and hydrogen.

[0047] Thus, even if the raw material gas G1 contains chlorosilanes that contain chlorine in their molecules and are corrosive, even if the material of the supply piping 20 is corroded and rust or chlorides are generated on the surface, and part of the rust or chlorides is mixed into the raw material gas G1, it is possible to prevent them from entering the reactor 10.

[0048] The chlorosilanes include, for example, tetrachlorosilane, trichlorosilane, dichlorosilane, or monochlorosilane, with trichlorosilane being generally suitable. In addition, polycrystalline silicon S1 manufactured using the aforementioned method for manufacturing polycrystalline silicon S1 also falls within the technical scope of the present invention.

[0049] [Implementation Method 2]

[0050] Hereinafter, Embodiment 2 of the present invention will be described. For the sake of convenience, components having the same functions as those described in Embodiment 1 are denoted by the same reference numerals, and their description will not be repeated. Figure 3 This is a diagram showing an example of the configuration of a filter 30A included in the apparatus for producing polycrystalline silicon S1 according to the second embodiment of the present invention. Figure 3 In FIG. 1 , the diagram indicated by FA is a front view of the filter 30A, and the diagram indicated by FB is a side view of the filter 30A.

[0051] The manufacturing apparatus according to the second embodiment is different from the manufacturing apparatus 1 according to the first embodiment in that the filter 30 is replaced with a filter 30A. Figure 3 As shown, a portion of the filter 30A has a tapered shape that tapers from a first end 31A connected to the connection member CN1 toward a second end 32A opposite the first end 31A. In other words, a portion of the filter 30A has a tapered shape that tapers from the inlet 111 toward the upstream side of the supply flow path.

[0052] Alternatively, at least a portion of the filter 30A may be tapered as it moves from the inlet 111 toward the upstream portion of the supply flow path. Conversely, the manufacturing apparatus according to Embodiment 2 may include, in place of the filter 30A, a filter having at least a portion tapered as it moves from the upstream portion of the supply flow path toward the inlet 111.

[0053] The configuration of the filter 30A reduces the chances of the flow of the raw gas G1 being obstructed by the filter 30A even when the raw gas G1 strikes the filter 30A, and reduces the pressure loss of the raw gas G1 caused by the installation of the filter 30A. Alternatively, consider using a filter in which at least a portion of the filter has a tapered shape that tapers from the upstream of the supply flow channel toward the inlet 111. In this case, the space through which the raw gas G1 passes expands from the upstream of the supply flow channel toward the inlet 111, allowing the raw gas G1 to pass smoothly. Consequently, the pressure loss of the raw gas G1 caused by the installation of the filter can be reduced.

[0054] like Figure 3 As shown in the figure FB in FIG, a notch surface 35 is formed in filter 30A by notching a portion of surface 34 of filter 30A. By attaching a plate filter 36 to notch surface 35, plate filter 36 forms a filtering surface. Furthermore, notch surface 35 and plate filter 36 may extend between first end 31A and second end 32A.

[0055] The cutout surface 35 and the plate-shaped filter 36 have a shape in which the width thereof increases along a direction perpendicular to the extending direction of the filter 30A as it moves from the first end 31A toward the second end 32A. Figure 3 As shown, the cutout surface 35 and the plate filter 36 are formed at two locations symmetrically with respect to the center line L1 of the filter 30A along the extension direction of the filter 30A. The plate filter 36 can be attached by welding or fusion bonding, specifically welding, crimping, or welding.

[0056] <Filtration accuracy of filter 30A>

[0057] Figure 4 Yes Figure 3 The figure shows the filtration accuracy of filter 30A. According to the results of impurity observation by the present inventors using a scanning electron microscope, the impurities mixed in the raw gas G1 supplied to the reactor 10 are approximately 1 μm or larger in size. Therefore, the filtration accuracy of filter 30A for particles with a diameter of 1 μm or larger is preferably 95% or higher. In other words, filter 30A preferably removes 95% of particles with a diameter of 1 μm or larger.

[0058] In addition, from the perspective of removing even finer impurities by the filter 30A, Figure 4 As shown, the filtration accuracy of filter 30A for particles with a diameter of 0.3 μm or greater is preferably 90% or greater. In other words, filter 30A preferably removes at least 90% of particles with a diameter of 0.3 μm or greater. This configuration allows for efficient removal of impurities mixed into raw gas G1.

[0059] The term "filtration accuracy" used in this manual refers to the filtration accuracy measured using the following method. The following describes, for example, the measurement of the filtration accuracy of filter 30A. First, using a dry dispersion aerosol generator (RBG1000, manufactured by PALAS), air cleaner test dust (hereinafter referred to as AC dust) is supplied to the upstream side of filter 30A.

[0060] At this time, the syringe used to supply the compressed AC dust powder had a diameter of 7 mm and a supply rate of 5 mm / h. This supply rate corresponds to a supply rate of 190 mg / h, assuming a bulk density of 1 g / cc.

[0061] In addition, while supplying AC dust, dilution air was supplied to the upstream side of the filter 30A at a flow rate of 40 L / min. Next, the particle size distribution upstream of the filter 30A was measured for 20 seconds, and then the particle size distribution downstream of the filter 30A was measured for 20 seconds. Furthermore, for each particle size, the average number of particles downstream of the filter 30A [number of particles / cm 3 ] divided by the average number of particles upstream of the filter 30A [number of particles / cm 3 ] to calculate the filtration accuracy of the particle size.

[0062] The particle size distribution measurement upstream of the filter 30A and the particle size distribution measurement downstream of the filter 30A were repeated three times, and the average value of the filtration accuracy calculated in these three measurements was set as the final filtration accuracy of the filter 30A. Figure 4 Filter fineness shown. Figure 4 In the figure, the horizontal axis represents the particle size [μm] and the vertical axis represents the filtration accuracy [%].

[0063] Figure 4 In the measurement results shown, the filter 30A was used as the filter, and a filter made of a sintered body was used as the plate filter 36. In addition, in the measurement results, a filter made of SUS316L was used as the filter 30A, and the dimensions of the filter 30A are shown below.

[0064] like Figure 3 As shown in the figure FA, the length M1 of the opening of the filter 30A along the direction in which the filter 30A extends is 300 mm, and the length M2 of the front end T1 of the filter 30A along the direction in which the filter 30A extends is 50 mm. The thickness of the plate filter 36 is 1 mm. The filter 30A is manufactured by cutting a portion of a pipe having an outer diameter of 27.2 mm and an inner diameter of 23.9 mm.

[0065] [Implementation Method 3]

[0066] Hereinafter, Embodiment 3 of the present invention will be described. For the sake of convenience, components having the same functions as those described in Embodiments 1 and 2 are denoted by the same reference numerals, and their description will not be repeated. Figure 5 This is a diagram showing an example of the configuration of a filter included in the apparatus for producing polycrystalline silicon S1 according to the third embodiment of the present invention. Figure 5 In FIG. 1 , the diagram indicated by FC is a front view of the filter 30B, and the diagram indicated by FD is a perspective view of the filter 30C.

[0067] The manufacturing apparatus according to the third embodiment is different from the manufacturing apparatus 1 according to the first embodiment in that the filter 30 is changed to a filter 30B or a filter 30C. Figure 5 As shown in the figure FC in FIG, the filter 30B is composed of a cylindrical portion 41, a central portion 42, and a conical portion 43. The cylindrical portion 41, the central portion 42, and the conical portion 43 are formed in this order from the downstream side of the supply flow path.

[0068] Cylindrical portion 41 has a cylindrical shape and is connected to connecting member CN1. Central portion 42 has a shape obtained by cutting off the top of a cone. Conical portion 43 has a conical shape. Central portion 42 and conical portion 43 are formed so that the inclination angle of central portion 42 is smaller than the inclination angle of conical portion 43.

[0069] A portion of the filter 30B may have the aforementioned tapered shape formed by the central portion 42 and the tapered portion 43. The configuration of the filter 30B makes it less likely that the flow of the raw gas G1 is obstructed by the filter 30B. Furthermore, the entire filter included in the manufacturing apparatus according to Embodiment 3 may have a tapered shape.

[0070] In addition, if Figure 5 As shown in the diagram FD in FIG. 3 , filter 30C has a triangular prism shape. Of the three quadrilateral faces of the triangular prism of filter 30C, the quadrilateral face 44 with the smallest area is connected to connecting member CN1. Alternatively, filter 30C may have face 44 with a polygonal shape other than a quadrilateral.

[0071] Of the three quadrilateral faces of the triangular prism of filter 30C, two faces 45 and 46 other than face 44 extend along the supply channel. Filter 30C may also have the cone shape formed by the triangular prism. Furthermore, the filter included in the manufacturing apparatus according to Embodiment 3 may also have a polygonal pyramid shape, such as a triangular pyramid or a quadrilateral pyramid. In this case, the base of the polygonal pyramid is connected to the connecting member CN1, and the top is positioned upstream of the supply channel.

[0072] [Implementation Method 4]

[0073] Hereinafter, a fourth embodiment of the present invention will be described. For the sake of convenience, components having the same functions as those described in the first to third embodiments are denoted by the same reference numerals, and their description will not be repeated. Figure 6 This is a diagram showing an example of the configuration of a filter included in the apparatus for producing polycrystalline silicon S1 according to the fourth embodiment of the present invention. Figure 6 , the figure indicated by FE is a front view of the filter 30D, and the figure indicated by FF is a side view of the filter 30D.

[0074] The manufacturing apparatus according to the fourth embodiment is different from the manufacturing apparatus 1 according to the first embodiment in that the filter 30 is replaced with a filter 30D. Figure 6 As shown in FIG. FE in FIG. , the filter 30D has a disk shape. An opening 48 is formed at the center of a flat surface 47 on the front side of the filter 30D. A plate-shaped filter 49 is attached to the opening 48 so as to block the opening 48.

[0075] In addition, if Figure 6 As shown in the figure FF in FIG, the filter 30D includes a side surface 51. The side surface 51 is connected to the connecting member CN1. In this case, the filter 30D preferably extends in a direction perpendicular to the flow direction of the raw gas G1 flowing in the supply flow channel. Furthermore, the shape of the filter 30D is not limited to a disc. For example, the plane perpendicular to the flow direction of the raw gas G1 may be a quadrilateral or a triangle other than a circle. Furthermore, the filter 30D may extend in a direction inclined from the direction perpendicular to the flow direction of the raw gas G1 flowing in the supply flow channel.

[0076] [Summarize]

[0077] A polysilicon manufacturing device according to one embodiment of the present invention comprises: a reactor, which accommodates a raw material gas for silicon precipitation; a piping, which forms a supply flow channel, the supply flow channel including an inlet formed in the reactor through which the raw material gas flows, the supply flow channel being used to supply the raw material gas into the reactor; and a filter, which is arranged in the supply flow channel and removes impurities mixed in the raw material gas.

[0078] According to the above configuration, impurities mixed in the raw material gas for silicon precipitation can be removed by the filter, so that polycrystalline silicon can be produced by supplying the raw material gas from which impurities have been removed into the reactor.

[0079] The filter may be provided at the inlet of the supply flow channel. According to the above configuration, by providing the filter at the inlet, the amount of impurities that enter the reactor can be minimized.

[0080] The raw material gas may be a mixed gas of chlorosilanes and hydrogen. With this configuration, even if the raw material gas contains corrosive chlorosilanes containing chlorine in their molecules, even if piping materials corrode and rust or chlorides form on their surfaces, and some of the rust or chlorides mix with the raw material gas, they can be prevented from entering the reactor.

[0081] The pipe forming the supply flow path may be made of stainless steel. This configuration prevents the intrusion of at least one of the heavy metal elements Fe (iron), Ni (nickel), Cr (chromium), Mn (manganese), Cu (copper), Ti (titanium), Mo (molybdenum), and Nb (niobium) into the reactor, which is caused by the constituent elements of the stainless steel.

[0082] The filter can achieve a filtration accuracy of 90% or higher for particles having a particle diameter of 0.3 μm or higher. According to the above configuration, impurities mixed in the raw material gas can be removed efficiently.

[0083] At least a portion of the filter may have a tapered shape that tapers from the inlet toward the upstream of the supply flow channel, or may have a tapered shape that tapers from the upstream of the supply flow channel toward the inlet.

[0084] In the above configuration, it is contemplated to use a filter having at least a portion thereof having a tapered shape that tapers as it moves from the inlet toward the upstream portion of the supply channel. In this case, even if the raw gas strikes the filter, the flow of the raw gas can be less obstructed by the filter, and the pressure loss of the raw gas caused by the filter can be reduced.

[0085] Alternatively, consider using a filter in which at least a portion of the filter has a tapered shape that tapers from the upstream side of the supply channel toward the inlet. In this case, the space through which the raw gas passes expands as it moves from the upstream side of the supply channel toward the inlet, allowing for smoother passage of the raw gas. This can reduce the pressure loss of the raw gas caused by the filter.

[0086] The filter has the following shape: the first end is open, the second end opposite to the first end is closed, and the filtering surface extends between the first end and the second end; the outer peripheral side of the first end can be fixed to the inner wall of the supply channel in a manner that the first end and the second end are arranged along the inner wall of the supply channel.

[0087] This configuration increases the surface area of the filter, thereby reducing the pressure loss of the raw material gas caused by the filter. Furthermore, the raw material gas can be stably supplied until polysilicon precipitation is complete without closing the filter. This allows for efficient polysilicon production.

[0088] A method for manufacturing polycrystalline silicon according to one embodiment of the present invention includes: an impurity removal step, wherein a filter is provided in a supply flow path for supplying a raw material gas into a reactor containing the raw material gas for silicon precipitation, and impurities mixed in the raw material gas are removed by the filter; and a silicon precipitation step, wherein polycrystalline silicon is precipitated by supplying the raw material gas from which the impurities have been removed in the impurity removal step into the reactor.

[0089] The impurity removal step may be performed immediately before the raw material gas is supplied into the reactor. According to the above configuration, by performing the impurity removal step immediately before the raw material gas is supplied into the reactor, the amount of impurities entering the reactor can be minimized.

[0090] The polycrystalline silicon according to one aspect of the present invention can be produced by the above-described method for producing polycrystalline silicon.

[0091] The present invention is not limited to the aforementioned embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0092] Example

[0093] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples. A polycrystalline silicon rod is manufactured using a manufacturing apparatus for polycrystalline silicon S1 having the structure of the second embodiment of the present invention. That is, Figure 1 In the manufacturing apparatus 1 shown, polycrystalline silicon rods are manufactured using a device in which the filter 30 is replaced with a filter 10A. The reactor 10 can stand up ten polycrystalline silicon rods (five pairs of inverted U-shaped polycrystalline silicon S1). The manufacturing of polycrystalline silicon rods using this manufacturing apparatus for polycrystalline silicon S1 is carried out as described below.

[0094] Power is applied to each inverted U-shaped silicon core wire, 2000 mm in height, installed on the bottom 11 of the reactor 10, heating the core wires to approximately 1000°C. Furthermore, a mixed gas of fully purified trichlorosilane and hydrogen is supplied to the reactor 10 through a supply pipe 20, causing polycrystalline silicon to be deposited on each of the silicon core wires (each side of the square cross section is 8 mm). Polycrystalline silicon deposition continues until the polycrystalline silicon rods reach a diameter of 120 mm.

[0095] In addition, in the manufacturing device of the polycrystalline silicon S1, the supply pipe 20 is made of stainless steel. Before the implementation of this embodiment, the manufacturing of polycrystalline silicon rods was repeated 100 times under the same conditions. Figure 3The material shown is a filter 30A made of SUS316L. The filtration accuracy of the filter 30A is such that it can remove more than 90% of particles with a particle size of 0.3 μm or more. The installation position of the filter 30A relative to the supply pipe 20 is Figure 2 Installation location shown.

[0096] The contamination status of each polycrystalline silicon rod produced under the above conditions was confirmed by metal impurities. The contamination status was confirmed as follows. A cylindrical object with a diameter of 10 mm and a length of 120 mm was hollowed out from the polycrystalline silicon rod near the middle of the rod's longitudinal direction in a horizontal direction perpendicular to the longitudinal direction. The cylindrical object extended in the horizontal direction.

[0097] The polysilicon cylinder obtained by digging out the polysilicon rod was studied. Here, the so-called radial direction is the radial direction of the cross section of the polysilicon rod. The cylinder was vertically cut from a position 4 mm inward in the radial direction from one end of the cylinder (the outer skin surface of the polysilicon rod) and 2 mm in front and back in the radial direction to obtain a cylindrical outer skin portion measurement sample with a diameter of 10 mm and a height of 4 mm. Similarly, the cylinder was vertically cut from a position 30 mm from one end of the cylinder (the outer skin surface) (a position of 1 / 2 of the radius involved in the cross section of the polysilicon rod) and 2 mm in front and back in the radial direction to obtain a middle portion measurement sample. Furthermore, in the cylinder, the cylinder was vertically cut at the center position of the cross section of the polysilicon rod and at a position 4 mm outward in the radial direction from the center position to obtain a core portion measurement sample.

[0098] The metal content of each of these measurement samples was analyzed. Specifically, the amount of each metal element, Cr, Fe, and Ni, was analyzed using inductively coupled plasma mass spectrometry (ICP-MS) in a solution obtained by dissolving the target measurement sample in a fluorine-nitric acid mixed solution. For each measurement sample, the average of the analyzed values for ten polycrystalline silicon rods was calculated, and this value was used as the metal concentration in each section of the polycrystalline silicon rod. The metal concentrations in each section are shown in Table 1 below as the results of this example.

[0099] [Table 1]

[0100] Cr[pptw] Fe[pptw] Ni[pptw] Core wire 9 29 2 middle part 4 19 2 Outer skin 1 12 3

[0101] Comparative Example

[0102] In the comparative example, polycrystalline silicon rods were produced in the same manner as in the example, except that the filter 30A was not installed on the supply pipe 20. The contamination status of each polycrystalline silicon rod obtained was confirmed by the same method as in the example. The metal concentrations at various locations are shown in Table 2 below as the results of this comparative example.

[0103] [Table 2]

[0104] Cr[pptw] Fe[pptw] Ni[pptw] Core wire 13 59 7 middle part 7 54 8 Outer skin 2 17 7

[0105] A comparison of Tables 1 and 2 shows that the polycrystalline silicon rods of the Example exhibit significantly lower concentrations of Cr, Fe, and Ni in the core, middle, and sheath portions compared to the polycrystalline silicon rods of the Comparative Example. These results confirm the significant suppressive effect of providing filter 30A in supply piping 20 on contamination by metallic impurities.

[0106] Industrial applicability

[0107] The present invention can be used to manufacture polycrystalline silicon.

[0108] Explanation of symbols

[0109] 1 Polysilicon manufacturing equipment

[0110] 10 Reactors

[0111] 20 Supply piping (piping)

[0112] 30, 30A, 30B, 30C, 30D filters

[0113] 31, 31A first end

[0114] 32, 32A Second end

[0115] 33 filter surface

[0116] 111, E1 inlet

[0117] G1: Raw gas

[0118] S1 polysilicon

Claims

1. A polysilicon manufacturing device, characterized in that: have: A reactor containing a raw material gas for silicon precipitation, wherein the raw material gas is a mixed gas of trichlorosilane and hydrogen; a pipe forming a supply flow channel, the supply flow channel including an inlet formed on the reactor through which the raw material gas flows, the supply flow channel being used to supply the raw material gas into the reactor; as well as A filter is provided at the inlet of the supply flow channel and removes impurities mixed in the raw gas, wherein the filter is made of stainless steel containing 10% by mass or more of Ni, For particles with a diameter of 0.3 μm or more, the filter has a filtration accuracy of more than 90%. The filter has a shape in which a first end is open, a second end opposite to the first end is closed, and a filter surface extends between the first end and the second end; and The outer peripheral side of the first end is fixed to the inner wall of the supply flow channel so that the first end and the second end are aligned along the inner wall of the supply flow channel.

2. The polycrystalline silicon manufacturing device according to claim 1, wherein The pipe forming the supply flow path is made of stainless steel.

3. The polycrystalline silicon manufacturing device according to claim 1 or 2, characterized in that: At least a portion of the filter has a tapered shape that tapers from the inlet toward the upstream of the supply flow channel, or has a tapered shape that tapers from the upstream of the supply flow channel toward the inlet.

4. A method for producing polycrystalline silicon, characterized in that: include: an impurity removal step, wherein a reactor contains a raw material gas for silicon precipitation and is provided with an inlet for the raw material gas, wherein the raw material gas is a mixed gas of trichlorosilane and hydrogen; a supply flow path for supplying the raw material gas into the reactor includes the inlet, and impurities mixed in the raw material gas are removed by a filter provided at the inlet; and a silicon precipitation step of precipitating polycrystalline silicon by supplying the raw material gas from which the impurities have been removed in the impurity removal step into the reactor; In the impurity removal step, the filter is made of stainless steel containing 10% by mass or more of Ni, and For particles with a diameter of 0.3 μm or more, the filter has a filtration accuracy of more than 90%. The filter has a shape in which a first end is open, a second end opposite to the first end is closed, and a filter surface extends between the first end and the second end; and The outer peripheral side of the first end is fixed to the inner wall of the supply flow channel so that the first end and the second end are aligned along the inner wall of the supply flow channel.

5. The method for producing polycrystalline silicon according to claim 4, wherein: The impurity removal step is performed immediately before the raw material gas is supplied into the reactor.

6. A polycrystalline silicon, characterized in that: The polycrystalline silicon is produced by the method for producing polycrystalline silicon according to claim 4 or 5.

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