Test structure of manufacturing apparatus for polycrystalline silicon, test method, and manufacturing method for polycrystalline silicon

Abstract

To provide a test structure of a manufacturing apparatus for polycrystalline silicon with which the amount of fine silicon powder in exhaust gas discharged from a reaction vessel of polycrystalline silicon is detected with high accuracy.SOLUTION: A test structure (20) of an apparatus (1) for manufacturing polycrystalline silicon comprises a sampling pipe (21) which is inserted into an exhaust gas pipe (13) through which exhaust gas from a reaction vessel (12) for depositing polycrystalline silicon flows, and in which a sampling port (21a) for the exhaust gas is formed, a control valve (24) for causing the flow rate of the exhaust gas flowing through the sampling pipe (21) to be 80% or more and 120% or less of the flow rate of the exhaust gas in the exhaust gas pipe (13), and a collection section (22) for collecting fine particles in the exhaust gas flowing through the sampling pipe (21). The sampling pipe (21) is inserted into the exhaust gas pipe (13) so that the flow direction of the exhaust gas into the sampling pipe (21) is parallel to the flow direction of the exhaust gas in the exhaust gas pipe (13).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a test structure and a test method for a polycrystalline silicon manufacturing apparatus, and a method for manufacturing polycrystalline silicon. [Background technology]

[0002] Polycrystalline silicon is preferably used as a raw material for semiconductor devices and solar power generation cells. For example, polycrystalline silicon is produced by precipitating polycrystalline silicon from a mixed gas of chlorosilanes and hydrogen in a reaction vessel. Depending on the reaction conditions, a large amount of silicon powder may be generated as a by-product.

[0003] The silicon powder not only adheres to piping and causes the piping to become clogged, but also causes damage to equipment installed downstream of the reaction vessel, such as pumps. In order to find polycrystalline silicon production conditions that can reduce the amount of such powder generated, a method for accurately measuring the amount of powder generated is required.

[0004] For example, Patent Document 1 discloses a method for detecting dust deposition inside a reaction space for producing polycrystalline silicon by measuring the haze inside the reaction space. Patent Document 2 discloses a method for detecting the degree of atomization during a reduction reaction by providing a gas line for exhaust gas in a polycrystalline silicon reduction reaction, installing an exhaust gas filter on the gas line, and detecting the degree of atomization during the reduction reaction from the differential pressure value of the exhaust gas before and after the exhaust gas filter. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2022-540735 [Patent Document 2] China Patent Publication No. 115615870 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the present inventors have found that there is room for improvement in the accuracy of detecting the amount of silicon fine powder generated in these conventional techniques.

[0007] One aspect of the present invention aims to realize a test structure, etc., that can detect with high accuracy the amount of silicon powder in exhaust gas discharged from a polycrystalline silicon reaction vessel when testing polycrystalline silicon production conditions. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, a test structure of a polycrystalline silicon manufacturing apparatus according to one embodiment of the present invention comprises: a collection pipe that is inserted into an exhaust gas piping through which exhaust gas that may contain silicon fine powder and is discharged from a reaction vessel for precipitating polycrystalline silicon flows, and has a collection port formed therein for collecting the exhaust gas from the exhaust gas piping; an adjustment valve for adjusting the flow speed of the exhaust gas flowing through the collection pipe to a speed that is 80% or more and 120% or less of the flow speed of the exhaust gas in the exhaust gas piping; and a collection section that collects the fine powder in the exhaust gas flowing through the collection pipe, and the collection pipe is inserted into the exhaust gas piping so that the flow direction of the exhaust gas into the collection pipe is parallel to the flow direction of the exhaust gas in the exhaust gas piping.

[0009] In order to solve the above-mentioned problems, a method for testing a polycrystalline silicon manufacturing apparatus according to one embodiment of the present invention includes a sampling process for sampling the exhaust gas from a sampling pipe that is inserted into an exhaust gas piping through which exhaust gas that may contain silicon fine powder and is discharged from a reaction vessel for precipitating polycrystalline silicon flows, the sampling pipe having a sampling port for sampling the exhaust gas from the exhaust gas piping, an adjustment process for adjusting the flow velocity of the exhaust gas in the sampling pipe to a velocity that is 80% or more and 120% or less of the flow velocity of the exhaust gas in the exhaust gas piping, and a collection process for collecting the fine powder in the exhaust gas flowing through the sampling pipe, wherein the sampling pipe is inserted into the exhaust gas piping so that the flow direction of the exhaust gas into the sampling pipe is parallel to the flow direction of the exhaust gas in the exhaust gas piping.

[0010] In order to solve the above-mentioned problems, a method for producing polycrystalline silicon according to one embodiment of the present invention, in which polycrystalline silicon is precipitated from a mixed gas of chlorosilanes and hydrogen gas in the reaction vessel, includes each step of the test method, and further includes a control step of controlling the precipitation reaction of the polycrystalline silicon depending on an evaluation result of the amount of the fine powder collected in the collection step. Effect of the Invention

[0011] According to one aspect of the present invention, a test structure or the like can be realized that can detect with high accuracy the amount of silicon powder in exhaust gas discharged from a polycrystalline silicon reaction vessel in testing of polycrystalline silicon manufacturing conditions. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a configuration of a polycrystalline silicon manufacturing apparatus according to an embodiment of the present invention. [Diagram 2] 2 is an enlarged view of a range A shown in FIG. 1, and is a schematic diagram showing a manner in which a sampling pipe is inserted into an exhaust gas pipe. [Diagram 3] FIG. 4 is a schematic diagram illustrating an inflow state of exhaust gas into a sampling pipe. [Figure 4] 2 is an enlarged view of a range A shown in FIG. 1, and is a schematic diagram showing a modified example of the manner in which the sampling pipe is inserted into the exhaust gas pipe. FIG. [Diagram 5] 2 is an enlarged view of a range A shown in FIG. 1, and is a schematic diagram showing a modified example of the manner in which the sampling pipe is inserted into the exhaust gas pipe. FIG. [Figure 6] 2 is a schematic diagram showing the periphery of a sampling port formed in the sampling pipe shown in FIG. 1. [Figure 7] FIG. 1 is a flow diagram showing a method for producing polycrystalline silicon according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, one embodiment of the present invention will be described in detail. In this specification, "A to B" expressing a numerical range means "A or more and B or less" unless otherwise specified.

[0014] [Polycrystalline silicon manufacturing equipment] 1, a polycrystalline silicon manufacturing apparatus 1 according to an embodiment of the present invention includes a main body 10 and a test structure 20. The polycrystalline silicon manufacturing apparatus 1 is an apparatus for depositing polycrystalline silicon from a mixed gas of chlorosilanes and hydrogen gas.

[0015] (Main body) The main body 10 may include a supply gas pipe 11, a reaction vessel 12, an exhaust gas pipe 13, and a first flow meter 14. It is also possible to manufacture polycrystalline silicon using the main body 10 alone.

[0016] The supply gas pipe 11 is a pipe for supplying a supply gas used for depositing polycrystalline silicon to the reaction vessel 12. The supply gas pipe 11 is connected to the reaction vessel 12. The dashed arrows shown in FIG. 1 indicate the flow directions of the supply gas supplied to the reaction vessel 12 and the exhaust gas exhausted from the reaction vessel 12.

[0017] The supply gas may be a mixed gas containing chlorosilanes and hydrogen gas. Specific examples of the chlorosilanes include silane compounds such as trichlorosilane, tetrachlorosilane, monochlorosilane, and dichlorosilane. Among them, trichlorosilane may be preferably used as the chlorosilane.

[0018] Reaction vessel 12 is a vessel for carrying out a precipitation reaction of polycrystalline silicon inside. Inside reaction vessel 12, polycrystalline silicon is precipitated by a reaction between chlorosilanes contained in the supply gas supplied from supply gas pipe 11 and hydrogen gas. Reaction vessel 12 may be, for example, a bell jar type reaction vessel, or may have any other shape as long as polycrystalline silicon can be precipitated inside.

[0019] The exhaust gas pipe 13 is a pipe through which the exhaust gas discharged from the reaction vessel 12 flows. The exhaust gas pipe 13 is connected to the reaction vessel 12. The exhaust gas may contain silicon fine powder generated by the precipitation reaction of polycrystalline silicon. Hereinafter in this specification, the term "fine powder" refers to silicon fine powder unless otherwise specified.

[0020] In the polycrystalline silicon precipitation reaction, fine powder may be generated depending on the reaction conditions. The fine powder may be mixed into the exhaust gas, causing clogging of the exhaust gas piping 13 through which the exhaust gas flows, and may cause failure of equipment such as a pump installed downstream of the reaction vessel 12. Therefore, in the test of the polycrystalline silicon production conditions, it is preferable to evaluate the amount of fine powder contained in the exhaust gas and optimize the polycrystalline silicon precipitation conditions in the reaction vessel 12 so as to reduce the amount of fine powder generated. Thus, the term "test" in this specification is intended to mean a test of the polycrystalline silicon production conditions and to evaluate the amount of fine powder mixed into the exhaust gas.

[0021] Polycrystalline silicon precipitation conditions that can affect the amount of fine powder generated include, but are not limited to, the amount of supply gas, the concentrations and ratios of chlorosilanes and hydrogen gas contained in the supply gas, and the reaction temperature.

[0022] The exhaust gas contains gas components generated by the deposition reaction in the reaction vessel 12 in addition to the gas components contained in the supply gas. Specifically, the exhaust gas contains at least one of hydrogen chloride and silanes. Examples of silanes contained in the exhaust gas include monosilane in addition to the above-mentioned chlorosilanes. The exhaust gas may further contain hydrogen and other reaction by-products.

[0023] The first flowmeter 14 is a sensor capable of measuring a gas flow rate in order to measure the flow velocity V1 of the exhaust gas flowing through the exhaust gas piping 13. The first flowmeter 14 may be, for example, an area type flowmeter or a flowmeter of another type. In addition, the first flowmeter 14 may have any configuration capable of measuring the amount of exhaust gas discharged from the reaction vessel 12, and may be provided, for example, at the exhaust gas outlet of the reaction vessel 12 instead of the exhaust gas piping 13.

[0024] When the first flowmeter 14 is attached to the exhaust gas piping 13, there is a concern that the flow of exhaust gas containing fine particles may cause clogging of the measuring section due to fine particles or deterioration of measurement accuracy. For this reason, it is desirable for the first flowmeter 14 to have a structure that allows easy disassembly and maintenance. The installation position of the first flowmeter 14 may be changed from the exhaust gas piping 13 to the supply gas piping 11. In this case, the measurement accuracy of the flow velocity V1 of the exhaust gas can be ensured by separately measuring the change in gas composition due to the reaction in the reaction vessel 12 and correcting it with the specific gravity difference between the supply gas flowing through the supply gas piping 11 and the exhaust gas flowing through the exhaust gas piping 13.

[0025] The main body 10 may further include configurations other than those described above. For example, the main body 10 may include a recovery device (not shown) for recovering silanes from the exhaust gas flowing through the exhaust gas piping 13 and / or a detoxification device (not shown) for detoxifying the exhaust gas. These recovery devices and / or detoxification devices are preferably provided downstream of the position where the sampling pipe 21 described below is inserted in the exhaust gas piping 13. The downstream side refers to the downstream side in the exhaust gas piping 13 in the flow direction of the exhaust gas, opposite the side connected to the reaction vessel 12.

[0026] (Test Structure) The test structure 20 is a structure for testing the polycrystalline silicon production conditions in the polycrystalline silicon production apparatus 1. The test structure 20 includes a sampling pipe 21, a collection unit 22, a temperature adjustment unit 23, an adjustment valve 24, and a second flow meter 25.

[0027] The sampling pipe 21 is a pipe that samples exhaust gas from the exhaust gas pipe 13 and distributes the exhaust gas. A portion of the sampling pipe 21 is inserted into the exhaust gas pipe. FIG. 2 is an enlarged view of region A shown in FIG. 1, and is a schematic diagram showing how the sampling pipe 21 is inserted into the exhaust gas pipe 13. FIG. 2 shows the inside of the exhaust gas pipe 13 by omitting the illustration of the portion of the exhaust gas pipe 13 on the front side of the page. Also, in FIG. 2, the flow direction of the exhaust gas is indicated by a dashed arrow, and this is the same for FIG. 3 to FIG. 6 described later.

[0028] 2, a sampling port 21a for sampling exhaust gas is formed at one end of the sampling pipe 21. The sampling pipe 21 is inserted into the exhaust gas pipe 13 so that the direction in which the exhaust gas flows into the sampling pipe 21 is parallel to the direction in which the exhaust gas flows in the exhaust gas pipe 13.

[0029] Note that "parallel" here does not require perfect parallelism, but is a concept that allows for manufacturing errors in the exhaust gas piping 13 and the sampling piping 21, positional deviations caused by inserting and fixing the sampling piping 21 into the exhaust gas piping 13, and distortions caused by use of the manufacturing apparatus 1.

[0030] Specifically, if the deviation of the exhaust gas inflow direction into the sampling pipe 21 from the exhaust gas flow direction in the exhaust gas pipe 13 is 5° or less, preferably 3° or less, there is no substantial difference in the accuracy of detecting the amount of fine particles in the exhaust gas, and this is acceptable as being in the category of "parallel." In other words, the manufacturing apparatus 1 may be one that is manufactured with the intention that the exhaust gas inflow direction into the sampling pipe 21 is parallel to the exhaust gas flow direction in the exhaust gas pipe 13.

[0031] The effect obtained by such a configuration will be described with reference to Fig. 3. In Fig. 3, the flow of fine particles contained in the exhaust gas is shown by a schematic broken line. Fig. 3 also shows the relationship between the flow velocity V1 of the exhaust gas in the exhaust gas piping 13 and the flow velocity V2 of the exhaust gas that flows into and through the collection piping 21.

[0032] 3, the direction in which the exhaust gas flows into the sampling pipe 210 is not parallel to the flow direction of the exhaust gas in the exhaust gas pipe (not shown) in Reference Example 1. In this case, even if fine particles and the like contained in the exhaust gas try to move in the direction in which they flow into the sampling port 210a of the sampling pipe 210, some of them cannot flow into the sampling pipe 210 due to the influence of inertial force.

[0033] 3, the direction in which the exhaust gas flows into the sampling pipe 21 is parallel to the direction in which the exhaust gas flows in the exhaust gas pipe 13. With this configuration, the sampling pipe 21 can sample, from the sampling port 21a, an amount of fine particles in the exhaust gas that accurately corresponds to the cross-sectional area of ​​the sampling port 21a. Therefore, the amount of fine particles contained in the exhaust gas flowing through the exhaust gas pipe 13 can be estimated with high accuracy from the amount of the fine particles in the exhaust gas that flows into the sampling pipe 21.

[0034] 2, the sampling pipe 21 has a bent portion 21b which is a portion that is bent to change the extension direction of the sampling pipe 21. The bent portion 21b is bent at 90 degrees to form an L-shape. When the sampling pipe 21 has multiple bent portions, the bent portion 21b refers to the bent portion located closest to the sampling port 21a in the extension direction of the sampling pipe 21.

[0035] In this embodiment, the portion of the sampling pipe 21 between the sampling port 21a and the bent portion 21b is referred to as the parallel portion 21c. The parallel portion 21c is a portion where the extension direction of the sampling pipe 21 is parallel to the extension direction of the exhaust gas pipe 13. It is preferable that at least the parallel portion 21c of the sampling pipe 21 is inserted into the exhaust gas pipe 13.

[0036] In the exhaust gas piping 13, the exhaust gas may become turbulent at a position immediately after the bent portion of the piping or after passing through various measuring instruments, instead of a uniform flow parallel to the piping. If the sampling piping 21 is installed in such a position, it is expected that the amount of fine particles will vary, resulting in a large variation in the measured value of the amount of fine particles, and measurement accuracy cannot be ensured, making this an undesirable installation position. From this perspective, it is desirable to install the sampling piping 21 downstream of a section that is 5 times or more, and preferably 10 times or more, the diameter of the exhaust gas piping 13, and away from bent portions of the piping or turbulent flow sources such as measuring instruments.

[0037] As a result, the sampling pipe 21 is inserted into the exhaust gas pipe 13 so that the flow direction of the exhaust gas into the sampling pipe 21 is parallel to the flow direction of the exhaust gas in the exhaust gas pipe 13. In addition, the sampling pipe 21 can be extended downstream of the bent portion 21b in a direction different from the extension direction of the exhaust gas pipe 13. This improves the design freedom of the test structure 20.

[0038] The structure of the portion of the sampling pipe 21 that is inserted into the exhaust gas pipe 13 is not limited to this. For example, as shown in Fig. 4, the bent portion 21b formed in the sampling pipe 21 may be a gently curved portion rather than a portion bent at 90 degrees or the like. Even in this case, a parallel portion 21c is formed in the sampling pipe 21 between the sampling port 21a and the portion where the bending of the bent portion 21b begins.

[0039] 5, when the sampling pipe 21 is inserted into the bent portion of the exhaust gas pipe 13, the portion of the sampling pipe 21 inserted into the exhaust gas pipe 13 may not include the bent portion 21b. In this case, the insertion position is adjusted so that the extension direction of the portion of the sampling pipe 21 inserted into the exhaust gas pipe 13 is parallel to the flow direction of the exhaust gas in the bent exhaust gas pipe 13.

[0040] In this way, the manner in which the sampling pipe 21 is inserted into the exhaust gas pipe 13 is not particularly limited and may be in various manners as long as the flow direction of the exhaust gas into the sampling pipe 21 is parallel to the flow direction of the exhaust gas in the exhaust gas pipe 13. In a manner that satisfies such conditions, the amount of fine particles contained in the exhaust gas flowing through the exhaust gas pipe 13 can be estimated with high accuracy from the amount of the fine particles in the exhaust gas that has flowed into the sampling pipe 21.

[0041] The shape of the end of the sampling pipe 21 that forms the opening surface of the sampling port 21a is not particularly limited as long as it does not prevent the inflow direction of the exhaust gas into the sampling pipe 21 from being parallel to the flow direction of the exhaust gas in the exhaust gas pipe 13. For example, as shown by reference numeral 601 in Fig. 6, the end of the sampling pipe 21 may be shaped to be perpendicular to the flow direction of the exhaust gas in the exhaust gas pipe 13. Also, as shown by reference numeral 602 in Fig. 6, the end of the sampling pipe 21 may be shaped to be inclined with respect to the flow direction of the exhaust gas in the exhaust gas pipe 13.

[0042] The collection section 22 is a member that collects fine powder in the exhaust gas flowing through the sampling pipe 21. The minimum size of the fine powder that can be collected by the collection section 22 is not particularly limited, but may be, for example, 5 μm or less in the major axis, 1 μm or less, or 0.5 μm or less. The major axis of the fine powder refers to the maximum distance between any two points on the fine powder.

[0043] The collection unit 22 may be, for example, a filter capable of collecting fine powder. When the collection unit 22 is a filter, the amount of fine powder contained in the exhaust gas can be evaluated by evaluating the degree of clogging of the filter for the collected fine powder. With this configuration, for example, while the main body 10 is producing polycrystalline silicon, the amount of fine powder generated in the reaction vessel 12 can be evaluated in approximately real time by the test structure 20.

[0044] When the collection unit 22 is a filter, the filtration accuracy of the filter may be 5 μm or less, 1 μm or less, or 0.5 μm or less. It is desirable to check the maximum diameter of the filter measured by the bubble point method in advance and to discontinue use of filters that may leak fine powder to be collected.

[0045] The "filtration accuracy" described in this specification means the filtration accuracy measured by the following method in accordance with the method described in International Publication No. WO2021 / 065685. In the following, for example, a case where the filtration accuracy of a filter, which is the collection unit 22, is measured will be described. First, using a dry dispersion type aerosol generator (for example, RBG1000, manufactured by PALAS), air cleaner test dust (hereinafter referred to as AC dust) is supplied to the upstream side of the filter. Note that an aerosol generator is a machine that generates an aerosol (a mixture of gas and fine solids (powder)) using powder and air.

[0046] In this case, the diameter of the syringe for supplying the compressed powder of AC dust is set to 7 mm, and the supply speed is set to 5 mm / h, which corresponds to a supply speed of 190 mg / h assuming that the bulk density of the compressed powder is 1 g / cc.

[0047] Simultaneously with the supply of the compressed powder from AC Dust, dilution air is supplied to the upstream side of the filter at a flow rate of 40 L / min. Next, the particle size distribution upstream of the filter is measured for 20 seconds, and then the particle size distribution downstream of the filter is measured for 20 seconds. Then, for each particle size, the average particle number downstream of the filter [number of particles / cm 3 ] is the average particle number upstream of the filter [particles / cm 3 ], the smallest diameter at which 99% or more of the particles are captured is determined as the filtration accuracy for that particle size.

[0048] The particle size distribution upstream of the filter and the particle size distribution downstream of the filter are measured three times, and the average value of the filtration accuracy calculated for each of these three measurements is determined as the final filtration accuracy of the filter.

[0049] The filtering accuracy thus measured defines the minimum size (major axis) of fine particles that the filter can capture. Therefore, according to the above-mentioned configuration, fine particles having a major axis of at least 1 μm can be captured by the filter. Such a filter can capture fine particles, including very small ones, that may affect the operation of the exhaust gas piping 13, etc.

[0050] Furthermore, the collection unit 22 is not limited to a filter, and may be, for example, a cyclone-type separator that utilizes centrifugal force. The collection unit 22 may be a member that collects fine particles contained in the exhaust gas together with the exhaust gas. An example of such a member is a gas tank. The amount of fine particles contained in the exhaust gas collected in the gas tank may be measured by a conventional method. An example of the conventional method is a method of measuring the haze of the exhaust gas collected in the gas tank, as described in Patent Document 1.

[0051] Temperature adjustment unit 23 is a member that adjusts the temperature of collection unit 22. Temperature adjustment unit 23 may be, for example, a heating unit that heats collection unit 22, a heat retention unit that keeps collection unit 22 warm, or a combination of a heating unit and a heat retention unit.

[0052] The heating part may be a pipe through which high-temperature gas such as steam flows, or may be a member that is heated by combustion or electricity. An example of the heat retaining part is a member that covers the collection part 22 with a heat insulating material. The heat insulating material is preferably a material that can withstand the temperature of the exhaust gas flowing through the sampling pipe 21 and the heating temperature of the heating part, and examples of the heat insulating material include metal and rock wool.

[0053] When temperature adjustment unit 23 has a combination of a heating unit and a heat retaining unit, the heat retaining unit may cover collection unit 22 together with the heating unit.

[0054] It is not essential that the test structure 20 includes the temperature adjustment unit 23, but when the collection unit 22 is a filter, it is preferable that the test structure 20 includes the temperature adjustment unit 23. As described above, the exhaust gas flowing through the sampling pipe 21 contains silanes. Silanes liquefy when the temperature drops below their boiling point. When the silanes liquefy, if the collection unit 22 is a filter, the liquefied silanes may adhere to the filter, causing an increase in the filter differential pressure.

[0055] Here, the filter pressure difference refers to the difference in pressure of the exhaust gas in sampling piping 21 before and after the filter, which is collection section 22. With respect to before and after the filter, the upstream side of the filter is the front side, and the downstream side of the filter is the rear side, in the flow direction of the exhaust gas in sampling piping 21. In the example of Fig. 1, in sampling piping 21, the exhaust gas piping 13 side of collection section 22 is the upstream side, and the regulating valve 24 side is the downstream side.

[0056] If the test structure 20 is provided with the temperature adjustment unit 23, it is possible to reduce the risk that liquefied silanes or the like adhere to the filter that is the collection unit 22 and the differential pressure of the filter increases. As a result, it is possible to prevent misinterpretation as an increase in the differential pressure of the filter due to fine powder collection, and as a result, it is possible to extend the operable period of the filter that is the collection unit 22 and the test structure 20. In addition, it becomes easy to accurately adjust the flow rate V2 of the exhaust gas by the adjustment valve 24 described later.

[0057] From such a viewpoint, it is preferable that the temperature adjustment unit 23 sets the collection unit 22 to a temperature at which liquefaction of silanes can be prevented. On the other hand, it is not preferable that the temperature adjustment unit 23 sets the temperature to exceed the heat-resistant temperature of the collection unit 22. Therefore, it is preferable that the temperature adjustment unit 23 sets the collection unit 22 to a temperature of 105°C or higher and 420°C or lower.

[0058] The adjustment valve 24 is a member for adjusting the flow rate V2 of the exhaust gas flowing through the sampling pipe 21. Specifically, the adjustment valve 24 is a valve for setting the flow rate V2 to 80% or more and 120% or less with respect to the flow rate V1 of the exhaust gas in the exhaust gas pipe 13.

[0059] Reference example 2 shown in FIG. 3 shows the case where the flow rate V2 is faster than the flow rate V1 (V1 < V2). In this case, since the fine powder in the exhaust gas flowing through the exhaust gas pipe 13 flows into the sampling pipe 21 excessively, the amount (concentration) of the fine powder contained in the exhaust gas flowing into the sampling pipe 21 is larger than the exhaust gas flowing through the exhaust gas pipe 13.

[0060] In addition, reference example 3 shown in FIG. 3 shows the case where the flow rate V2 is slower than the flow rate V1 (V1 > V2). In this case, since a part of the fine powder in the exhaust gas flowing through the exhaust gas pipe 13 cannot flow into the sampling pipe 21, the amount (concentration) of the fine powder contained in the exhaust gas flowing into the sampling pipe 21 is smaller than the exhaust gas flowing through the exhaust gas pipe 13.

[0061] As in the example of the present invention shown in Figure 3, if the flow velocity V2 is equal to the flow velocity V1 or is within a range that can be considered to be equal, the amount of fine powder relative to the amount of exhaust gas can be matched between the exhaust gas flowing into the sampling piping 21 and the exhaust gas flowing through the exhaust gas piping 13.

[0062] The regulating valve 24 allows the flow velocity V2 to be set to a value between 80% and 120% of the flow velocity V1, which is a range that can be considered to be constant relative to the flow velocity V1. By adjusting the flow velocity V2 within such a range, the amount of fine particles in the exhaust gas flowing into the sampling pipe 21 can be maintained with high precision without adjusting the flow velocity V2 too strictly during operation of the test structure 20. The flow velocity V2 adjusted by the regulating valve 24 may be between 80% and 120% of the flow velocity V1, preferably between 90% and 110%, more preferably between 95% and 105%, and most preferably 100% (constant velocity).

[0063] The regulating valve 24 may be, for example, a valve that increases the flow velocity V2 as the opening degree increases. Since it is assumed that the pressure of the exhaust gas flowing through the sampling pipe 21 is affected only by the exhaust gas flowing in from the exhaust gas pipe 13, it is usually difficult to imagine that the flow velocity V2 will be faster than the flow velocity V1. Therefore, the regulating valve 24 may be a valve that can increase the flow velocity V2 by increasing the opening degree.

[0064] Adjustment valve 24 may also be a valve that reduces flow velocity V2 as the opening degree increases. For example, it is possible to make flow velocity V2 faster than flow velocity V1 for exhaust gas flowing into collection pipe 21 by, for example, sucking the exhaust gas from collection pipe 21. In this case, adjustment valve 24 may be a valve that can adjust the amount of exhaust gas flowing from collection pipe 21 to a pipe that discharges or sucks the exhaust gas in order to reduce flow velocity V2.

[0065] The adjusting valve 24 may be, for example, a needle valve, but is not limited to this, and any known type of valve may be appropriately selected depending on the design of the test structure 20.

[0066] The test structure 20 may include a single regulating valve 24, or may include multiple regulating valves 24. When multiple regulating valves 24 are provided, the test structure 20 may include, for example, an regulating valve 24 for increasing the flow velocity V2 and an regulating valve 24 for decreasing the flow velocity V2. Furthermore, at least one of the regulating valves 24 provided in the test structure 20 may be for adjusting both the increase and decrease of the flow velocity V2. With such a configuration, the flow velocity V2 can be precisely adjusted.

[0067] The second flowmeter 25 is a sensor capable of measuring the gas flow rate in order to measure the flow velocity V2. The second flowmeter 25 may be, for example, an area type flowmeter, or may be a flowmeter of another type. The flow velocity V2 may be adjusted by the regulating valve 24 with reference to the measured values ​​of the first flowmeter 14 and the second flowmeter 25. The adjustment of the flow velocity V2 by the regulating valve 24 at this time may be performed manually, or may be performed automatically by a device (not shown) capable of acquiring the measured values ​​of the first flowmeter 14 and the second flowmeter 25 and opening and closing the regulating valve 24.

[0068] The flow velocity V2 of the exhaust gas may be adjusted, for example, by converting the measured values ​​measured by the first flow meter 14 and the second flow meter 25 into values ​​of gas linear velocity and comparing them. The gas linear velocity (m / s) indicates the gas flow rate per cross-sectional area of ​​the pipe, and the gas flow rate (m 3 / s) / cross-sectional area of ​​pipe (m 2 ) is calculated by

[0069] When the measured values ​​of the first flowmeter 14 and the second flowmeter 25 are gas flow rates, the value of "measurement value of the first flowmeter 14 / cross-sectional area of ​​the exhaust gas piping 13" may be compared with the value of "measurement value of the second flowmeter 25 / cross-sectional area of ​​the sampling piping 21." In addition, the value of "measurement value of the first flowmeter 14×(cross-sectional area of ​​the sampling piping 21 / cross-sectional area of ​​the exhaust gas piping 13)" may be compared with the measured value of the second flowmeter 25. In addition, the value of "measurement value of the second flowmeter 25×(cross-sectional area of ​​the exhaust gas piping 13 / cross-sectional area of ​​the sampling piping 21)" may be compared with the measured value of the first flowmeter 14.

[0070] From the viewpoint of estimating the amount of fine particles in the exhaust gas in the exhaust gas piping 13 with high accuracy, it is preferable to measure the flow velocity of the exhaust gas in the sampling piping 21 immediately before it flows into the collection section 22 as the flow velocity V2. Therefore, the second flow meter 25 may be located upstream of the collection section 22 in the sampling piping 21. When the collection section 22 is a filter, by taking into account the filter differential pressure, the flow velocity of the exhaust gas flowing into the collection section 22 can be easily calculated even if the second flow meter 25 is located downstream of the collection section 22.

[0071] According to the above-mentioned configuration, the fine powder in the exhaust gas flowing through the sampling pipe 21 is collected by the collection unit 22, and the amount of the collected fine powder is measured, thereby making it possible to estimate with high accuracy the amount of fine powder in the exhaust gas flowing through the exhaust gas pipe 13. This makes it easy to find production conditions that generate a small amount of fine powder in testing production conditions for polycrystalline silicon.

[0072] This reduces clogging of the exhaust gas piping 13 caused by fine powder and failure of equipment such as pumps installed downstream of the reaction vessel 12, enabling long-term operation of the polycrystalline silicon manufacturing apparatus 1. This effect also contributes to achieving, for example, Goal 12 "Ensure sustainable consumption and production patterns" of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0073] [Method for producing polycrystalline silicon] A method for producing polycrystalline silicon according to one embodiment of the present invention will be described with reference to Fig. 7. The method for producing polycrystalline silicon includes a collection step, an adjustment step, a collection step, and a control step. Among these, the collection step, the adjustment step, and the collection step are steps included in a method for testing a polycrystalline silicon production apparatus according to one embodiment of the present invention. That is, the method for producing polycrystalline silicon according to one embodiment of the present invention is a method including each step of the method for testing a polycrystalline silicon production apparatus according to one embodiment of the present invention.

[0074] (Testing Method) A method for testing a polycrystalline silicon manufacturing apparatus according to an embodiment of the present invention is performed by a test structure 20 included in the polycrystalline silicon manufacturing apparatus 1. Hereinafter, the test method will be described using an example in which the test structure 20 is used.

[0075] 7, first, exhaust gas is sampled from the exhaust gas pipe 13 by the sampling pipe 21 (S1, sampling step). Here, the description of each component of the manufacturing apparatus 1, such as the sampling pipe 21 and the exhaust gas pipe 13, has been already described in the section on the manufacturing apparatus 1, so will be omitted.

[0076] Next, the flow velocity V2 is adjusted to 80 to 120% of the flow velocity V1 (S2, adjustment step). The adjustment step is performed by the adjustment valve 24. With this method, the exhaust gas collected by the collection pipe 21 can be made to contain approximately the same amount of fine powder as the exhaust gas flowing through the exhaust gas pipe 13.

[0077] Next, fine particles in the exhaust gas flowing through the sampling pipe 21 are collected (S3, collection step).

[0078] (Control process) The amount of fine powder collected by such a test method may be used as an index for controlling the precipitation reaction of polycrystalline silicon in the control step of the polycrystalline silicon production method.

[0079] In the control step, the precipitation reaction of polycrystalline silicon is controlled according to the evaluation result of the amount of collected fine powder (S4). The method of evaluating the amount of collected fine powder may be appropriately selected depending on the method of collecting fine powder. As an example, the fine powder may be collected by a filter capable of collecting the fine powder, and the amount of collected fine powder may be evaluated by the increase per unit time of the difference in pressure between before and after the filter with respect to the pressure of the exhaust gas in the collection pipe 21.

[0080] The difference in pressure before and after the filter is the filter differential pressure described above. The more fine particles the filter collects, the more clogged it becomes, making it more difficult for exhaust gas to pass through. Therefore, the increase in the filter differential pressure per unit time is proportional to the amount of fine particles contained in the exhaust gas, and is therefore preferable as an evaluation index for the amount of fine particles.

[0081] According to this configuration, the amount of captured fine powder can be evaluated based on the increase in filter differential pressure per unit time, which can be easily measured while operating polycrystalline silicon production apparatus 1. Since the amount of captured fine powder obtained by the above-mentioned test method accurately reflects the amount of fine powder in the exhaust gas flowing through exhaust gas piping 13, the evaluation result of the amount of captured fine powder can be used to easily and accurately control the precipitation reaction while polycrystalline silicon is being precipitated.

[0082] In addition, when the fine particles are collected together with the exhaust gas in the gas tank, the amount of collected fine particles may be evaluated by evaluating the haze of the exhaust gas collected in the gas tank. In addition, the amount of collected fine particles may be evaluated by other methods.

[0083] The method for controlling the precipitation reaction of polycrystalline silicon may be appropriately selected according to the method for evaluating the amount of collected fine powder. For example, the control step may be a step of stopping the precipitation reaction when the evaluation result of the amount of collected fine powder indicates that the increase per unit time of the pressure difference before and after the filter exceeds a predetermined threshold value.

[0084] The predetermined threshold value may be set appropriately. For example, the predetermined threshold value may be the amount of fine powder generated that is empirically known to be likely to cause clogging of the exhaust gas piping 13 and breakdown of equipment such as a pump installed downstream of the reaction vessel 12.

[0085] The greater the amount of fine particles in the exhaust gas, the greater the increase in the filter differential pressure per unit time. According to the above configuration, when the amount of fine particles in the exhaust gas flowing through the exhaust gas piping 13 is large, the precipitation reaction can be stopped at an appropriate time. Since the generation of fine particles can be easily stopped by stopping the precipitation reaction, the flow of exhaust gas containing fine particles through the exhaust gas piping 13 can be minimized. This can reduce clogging of the exhaust gas piping 13 and failure of equipment such as pumps installed downstream of the reaction vessel 12.

[0086] The control step may also be a step of changing the conditions of the precipitation reaction to conditions that can reduce the amount of fine powder generated when the evaluation result of the amount of collected fine powder indicates that the increase per unit time of the pressure difference before and after the filter exceeds a predetermined threshold value. Examples of the conditions of the precipitation reaction that are changed include the reaction temperature, the supply amount of the supply gas, and the concentrations, ratios, and pressures of the chlorosilanes and hydrogen gas in the supply gas.

[0087] As described above, the test method according to one embodiment of the present invention allows the amount of fine particles trapped in exhaust gas to be evaluated with high accuracy. Also, the method for producing polycrystalline silicon including such a test method allows the precipitation reaction of polycrystalline silicon to be accurately controlled according to the amount of fine particles trapped in exhaust gas.

[0088] 〔summary〕 A test structure of a polycrystalline silicon manufacturing apparatus according to aspect 1 of the present invention includes a collection pipe that is inserted into an exhaust gas piping through which exhaust gas that may contain silicon powder and is discharged from a reaction vessel for precipitating polycrystalline silicon flows, and has a collection port formed therein for collecting the exhaust gas from the exhaust gas piping, a regulating valve for adjusting the flow speed of the exhaust gas flowing through the collection pipe to a speed that is 80% or more and 120% or less of the flow speed of the exhaust gas in the exhaust gas piping, and a collection section that collects the fine powder in the exhaust gas flowing through the collection pipe, and the collection pipe is inserted into the exhaust gas piping so that the flow direction of the exhaust gas into the collection pipe is parallel to the flow direction of the exhaust gas in the exhaust gas piping.

[0089] According to the above configuration, the flow direction of the exhaust gas into the sampling pipe is parallel to the flow direction of the exhaust gas in the exhaust gas pipe, so that the sampling pipe can sample exhaust gas containing silicon fine powder in an amount that accurately corresponds to the cross-sectional area of ​​the sampling port.

[0090] Furthermore, the greater the difference in exhaust gas flow velocity between the exhaust gas piping and the sampling piping, the more or less the amount of fine particles in the exhaust gas sampled in the sampling piping becomes compared to the amount of fine particles in the exhaust gas piping.The adjustment valve provided in the test structure adjusts the flow velocity of the exhaust gas flowing through the sampling piping to a speed between 80% and 120% of the flow velocity of the exhaust gas in the exhaust gas piping.This allows the amount of fine particles in the exhaust gas sampled in the sampling piping to accurately reflect the amount of fine particles in the exhaust gas flowing through the exhaust gas piping.

[0091] The fine particles contained in the exhaust gas collected in the collection pipe are collected by the collection section. By measuring the amount of the fine particles collected by the collection section, the amount of the fine particles present in the exhaust gas can be evaluated with high accuracy. By using such an evaluation method in the polycrystalline silicon production condition test, the amount of the fine particles in the exhaust gas can be reduced, thereby reducing clogging of the exhaust gas pipe and failure of equipment such as pumps installed downstream of the reaction vessel.

[0092] A test structure for a polycrystalline silicon manufacturing apparatus according to a second aspect of the present invention may be such that, in the first aspect, the collection section is a filter capable of collecting the fine powder.

[0093] According to the above-mentioned configuration, the amount of fine powder contained in the exhaust gas can be evaluated by evaluating the degree of clogging of the filter for the fine powder captured by the filter of the test structure. Since the amount of fine powder captured by the filter can be easily measured, for example, a process of capturing the fine powder together with the exhaust gas and measuring the amount of fine powder in the exhaust gas after the capture is not required, and the measurement of the amount of fine powder can be simplified.

[0094] A test structure for a polycrystalline silicon manufacturing apparatus according to a third aspect of the present invention is the same as the second aspect, in which the filter has a filtration accuracy of 1 μm or less.

[0095] The filtering accuracy defines the minimum size of fine particles that can be captured by the filter. Therefore, according to the above configuration, the filter can capture fine particles having a particle size of at least 1 μm. Therefore, the amount of fine particles in the exhaust gas can be measured with high accuracy.

[0096] The test structure for a polycrystalline silicon manufacturing apparatus according to a fourth aspect of the present invention may further include a temperature adjusting unit for adjusting the temperature of the filter to 105° C. or higher and 420° C. or lower in the second or third aspect.

[0097] According to the above-mentioned configuration, it is possible to prevent silane oligomers and the like contained in exhaust gas from liquefying when passing through the filter. Therefore, it is possible to reduce the risk of liquefied silane oligomers and the like adhering to the filter and increasing the pressure difference between the exhaust gas before and after the filter. This makes it possible to extend the operational life of the filter and the test structure. In addition, it becomes easy to adjust the flow rate of the exhaust gas with high precision using the regulating valve.

[0098] A test structure for a polycrystalline silicon manufacturing apparatus according to aspect 5 of the present invention is any one of aspects 1 to 4, wherein the sampling pipe has a bent portion, and at least the portion from the sampling port to the bent portion may be inserted into the exhaust gas pipe.

[0099] According to the above-mentioned configuration, it is easy to insert the sampling pipe into the exhaust gas pipe so that the opening surface of the sampling port is perpendicular to the flow direction of the exhaust gas, and to extend the sampling pipe in a direction different from the exhaust gas pipe. Therefore, the design freedom of the test structure can be improved.

[0100] A method for testing a polycrystalline silicon manufacturing apparatus according to a sixth aspect of the present invention includes a sampling process for sampling the exhaust gas from a sampling pipe that is inserted into an exhaust gas piping through which exhaust gas, which may contain silicon fine powder and is discharged from a reaction vessel for precipitating polycrystalline silicon, flows, the sampling pipe having a sampling port for sampling the exhaust gas from the exhaust gas piping, an adjustment process for adjusting the flow velocity of the exhaust gas in the sampling pipe to a velocity that is 80% or more and 120% or less of the flow velocity of the exhaust gas in the exhaust gas piping, and a collection process for collecting the fine powder in the exhaust gas flowing through the sampling pipe, wherein the sampling pipe is inserted into the exhaust gas piping so that the flow direction of the exhaust gas into the sampling pipe is parallel to the flow direction of the exhaust gas in the exhaust gas piping.

[0101] A method for producing polycrystalline silicon according to aspect 7 of the present invention includes each step of the test method described in aspect 6, and further includes a control step of controlling the precipitation reaction of the polycrystalline silicon in accordance with an evaluation result of the amount of the fine powder collected in the collection step, in the method for producing polycrystalline silicon in which polycrystalline silicon is precipitated from a mixed gas of chlorosilanes and hydrogen gas in the reaction vessel.

[0102] According to the above configuration, the precipitation reaction of polycrystalline silicon can be controlled according to the amount of fine particles collected in the exhaust gas. Since the above test method can evaluate the amount of fine particles collected in the exhaust gas with high accuracy, the precipitation reaction of polycrystalline silicon can be appropriately controlled based on the amount of fine particles generated.

[0103] A method for producing polycrystalline silicon according to an eighth aspect of the present invention is the same as that of the seventh aspect, wherein in the collection step, the fine powder is collected by a filter capable of collecting the fine powder, and the amount of the collected powder may be evaluated by an increase per unit time in the difference in pressure between before and after the filter with respect to the pressure of the exhaust gas in the sampling pipe.

[0104] According to the above-mentioned configuration, the amount of collected fine powder can be evaluated based on the increase per unit time of the pressure difference between before and after the filter, which can be easily measured while carrying out the polycrystalline silicon manufacturing method. Therefore, the precipitation reaction of polycrystalline silicon can be easily controlled.

[0105] In the method for producing polycrystalline silicon according to aspect 9 of the present invention, in aspect 8, the control process may include stopping the precipitation reaction when the evaluation result indicates that the increase in the pressure difference per unit time exceeds a predetermined threshold value.

[0106] The greater the amount of fine particles in the exhaust gas, the greater the increase in the pressure difference between before and after the filter per unit time. According to the above configuration, when the amount of fine particles in the exhaust gas is large, the precipitation reaction can be stopped at the appropriate time. Therefore, clogging of the exhaust gas piping and failure of equipment such as pumps installed downstream of the reaction vessel can be reduced.

[0107] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0108] 1 Manufacturing equipment 12 Reaction vessel 13 Exhaust gas piping 20 Test Structure 21 Collection piping 21a Sampling port 21b Bend part 22 Collection section 23 Temperature adjustment section 24 Regulating valve

Claims

1. a sampling pipe that is inserted into an exhaust gas pipe through which an exhaust gas that may contain silicon powder and is discharged from a reaction vessel for precipitating polycrystalline silicon flows, the sampling pipe having a sampling port for sampling the exhaust gas from the exhaust gas pipe; an adjusting valve for adjusting a flow velocity of the exhaust gas flowing through the sampling pipe to a flow velocity of the exhaust gas flowing through the exhaust gas pipe that is 80% or more and 120% or less of the flow velocity of the exhaust gas through the exhaust gas pipe; A collection section for collecting the fine particles in the exhaust gas flowing through the sampling pipe, A test structure for a polycrystalline silicon manufacturing apparatus, characterized in that the sampling pipe is inserted into the exhaust gas pipe so that the flow direction of the exhaust gas into the sampling pipe is parallel to the flow direction of the exhaust gas in the exhaust gas pipe.

2. The test structure according to claim 1 , wherein the collection portion is a filter capable of collecting the fine powder.

3. 3. The test structure of claim 2, wherein the filter has a filtering accuracy of 1 [mu]m or less.

4. 3. The test structure according to claim 2, further comprising a temperature adjustment unit for adjusting the temperature of the filter to a temperature of 105° C. or more and 420° C. or less.

5. 5. The test structure according to claim 1, wherein the sampling pipe has a bent portion, and at least a portion from the sampling port to the bent portion is inserted into the exhaust gas pipe.

6. a sampling process in which a sampling pipe is inserted into an exhaust gas pipe through which an exhaust gas that may contain silicon powder and is discharged from a reaction vessel for depositing polycrystalline silicon flows, the sampling pipe being provided with a sampling port for sampling the exhaust gas from the exhaust gas pipe, and the sampling pipe is used to sample the exhaust gas from the sampling port; an adjusting step of adjusting a flow velocity of the exhaust gas in the sampling pipe to a flow velocity of the exhaust gas in the exhaust gas pipe that is 80% or more and 120% or less of the flow velocity of the exhaust gas in the exhaust gas pipe; A collection step of collecting the fine particles in the exhaust gas flowing through the sampling pipe, 13. A method for testing a polycrystalline silicon manufacturing apparatus, comprising: inserting the sampling pipe into the exhaust gas pipe so that the flow direction of the exhaust gas into the sampling pipe is parallel to the flow direction of the exhaust gas in the exhaust gas pipe.

7. A method for producing polycrystalline silicon, comprising the steps of the test method according to claim 6, in which polycrystalline silicon is deposited from a mixed gas of chlorosilanes and hydrogen gas in the reaction vessel, 3. A method for producing polycrystalline silicon, comprising: a control step of controlling a precipitation reaction of the polycrystalline silicon in accordance with an evaluation result of an amount of the fine powder collected in the collection step.

8. In the collecting step, the fine powder is collected by a filter capable of collecting the fine powder, 8. The method for producing polycrystalline silicon according to claim 7, wherein the collected amount is evaluated based on an increase per unit time of a difference in pressure of the exhaust gas in the collection pipe between before and after the filter.

9. 9. The method for producing polycrystalline silicon according to claim 8, wherein in the control step, the precipitation reaction is stopped when the evaluation result indicates that an increase in the pressure difference per unit time exceeds a predetermined threshold value.

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