WO2024027341A1 - 一种清洁流化床内壁结硅的方法 - Google Patents

一种清洁流化床内壁结硅的方法 Download PDF

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WO2024027341A1
WO2024027341A1 PCT/CN2023/099427 CN2023099427W WO2024027341A1 WO 2024027341 A1 WO2024027341 A1 WO 2024027341A1 CN 2023099427 W CN2023099427 W CN 2023099427W WO 2024027341 A1 WO2024027341 A1 WO 2024027341A1
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gas
fluidized bed
silicon
wall
etching
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PCT/CN2023/099427
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English (en)
French (fr)
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朱共山
兰天石
樊晓冬
常露露
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江苏中能硅业科技发展有限公司
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
    • B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
    • B08B3/02—Cleaning by the force of jets or sprays
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
    • B08B3/04—Cleaning involving contact with liquid
    • B08B3/08—Cleaning involving contact with liquid the liquid having chemical or dissolving effect
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B08B9/08—Cleaning containers, e.g. tanks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B08B9/08—Cleaning containers, e.g. tanks
    • B08B9/083—Removing scrap from containers, e.g. removing labels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • B08B9/08—Cleaning containers, e.g. tanks
    • B08B9/093—Cleaning containers, e.g. tanks by the force of jets or sprays
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/029—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition of monosilane
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/03—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition of silicon halides or halosilanes or reduction thereof with hydrogen as the only reducing agent
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/035—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition or reduction of gaseous or vaporised silicon compounds in the presence of heated filaments of silicon, carbon or a refractory metal, e.g. tantalum or tungsten, or in the presence of heated silicon rods on which the formed silicon is deposited, a silicon rod being obtained, e.g. Siemens process
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
    • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B28/00—Production of homogeneous polycrystalline material with defined structure
    • C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
    • C30B28/14—Production of homogeneous polycrystalline material with defined structure directly from the gas state by chemical reaction of reactive gases
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/02—Elements
    • C30B29/06—Silicon
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B15/00—Fluidised-bed furnaces; Other furnaces using or treating finely-divided materials in dispersion
    • F27B15/02—Details, accessories, or equipment peculiar to furnaces of these types
    • F27B15/14—Arrangements of heating devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B2203/00—Details of cleaning machines or methods involving the use or presence of liquid or steam
    • B08B2203/002—Details of cleaning machines or methods involving the use or presence of liquid or steam the liquid being a degassed liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B2209/00—Details of machines or methods for cleaning hollow articles
    • B08B2209/02—Details of apparatuses or methods for cleaning pipes or tubes
    • B08B2209/027—Details of apparatuses or methods for cleaning pipes or tubes for cleaning the internal surfaces

Definitions

  • the present invention relates to equipment and methods for preparing polycrystalline silicon, in particular to equipment and methods for preparing granular silicon through fluidized bed equipment, and specifically to equipment and methods for removing silicon deposited on the inner wall of a fluidized bed during the polycrystalline silicon production process.
  • polysilicon As a basic material in the field of semiconductors and solar cells, polysilicon is widely used in the production of small but complex precision systems including various electronic logic devices, memory devices, discrete devices, etc. It is also used in solar panels.
  • the direct raw material of PN junction for photoelectric conversion It can be said that today's human civilization is largely based on silicon atoms. With the further development of human civilization, the demand for high-precision electronic systems and the demand for clean energy such as solar energy have become stronger, leading to further growth in the demand for polysilicon. Therefore, there is a need to provide a polycrystalline silicon production equipment and process with low cost, high output and good environmental safety.
  • the existing processes for producing polysilicon mainly include the improved Siemens method and the fluidized bed method.
  • the modified Siemens process is the most commonly used process, and its polysilicon production accounts for the vast majority of global polysilicon production.
  • the fluidized bed method is a process that has been gradually promoted in recent years, and its polysilicon production accounts for 10% of the world's polysilicon production. The ratio is increasing year by year.
  • the Siemens method (including the improved Siemens method) can also be called the hydrogen reduction method.
  • the main equipment used is a bell-type reactor, and the main raw materials are trichlorosilane and hydrogen.
  • a typical Siemens method for preparing polysilicon a polysilicon rod with a diameter of about 20 mm is heated in a bell jar reactor, so that the polysilicon reduced by hydrogen gas is deposited on the surface of the silicon rod, thereby making the silicon rod " "Grow up", when the volume of the silicon rod reaches a certain level, take out the silicon rod and you can get polycrystalline silicon products.
  • the Siemens method is widely used and has mature technology.
  • the purity of polysilicon products can be very high, so it is usually used to produce polysilicon products for semiconductors that require higher purity.
  • the Siemens method in order to avoid the deposition of elemental silicon on the inner wall of the bell jar reactor, the silicon rods are directly heated, and a cooling device is usually installed on the outer wall of the bell jar to make the temperature of the bell jar wall much lower than the temperature of the silicon rods, reducing the amount of elemental silicon. Silicon deposition in bell jar reaction gas housing.
  • the Siemens method has the problem of being unable to continue production due to the need to shut down the machine to remove the grown silicon rods, and polycrystalline silicon products need to go through additional crushing steps for downstream applications.
  • Fluidized bed method (including silane fluidized bed method), among which, silane fluidized bed method can also be called “silane gas thermal decomposition method", the main equipment used is usually called “fluidized bed”, and the raw materials used
  • the gas includes silicon-containing gases such as monosilane (SiH 4 ), silicon tetrachloride (SiCl 4 ), trichlorosilane (SiHCl 3 ), dichlorosilane (SiH 2 Cl 2 ), etc., which are heated and decomposed in the fluidized bed or After being reduced, the polycrystalline silicon produced deposits and grows on the surface of fine silicon particles (also known as "seeds") in the fluidized bed, thereby producing granular polycrystalline silicon products.
  • silicon-containing gases such as monosilane (SiH 4 ), silicon tetrachloride (SiCl 4 ), trichlorosilane (SiHCl 3 ), dichlorosilane (SiH 2 Cl 2 ), etc.
  • the flow The production efficiency of the chemical bed method is much greater than that of the Siemens method.
  • the silicon-containing raw material gas due to the low thermal decomposition temperature of the silicon-containing raw material gas, for example, at a temperature of 300 to 400°C, the silicon-containing raw material gas has begun to decompose.
  • the heating temperature of the silicon-containing raw gas in the existing fluidized bed production process is usually between 500 and 700°C, and its energy consumption is relatively low. Therefore, the fluidized bed method for preparing granular silicon has been widely used in recent years.
  • existing fluidized bed process equipment still has certain problems: due to the need to integrally heat the silicon-containing raw gas in the fluidized bed, existing heating methods including resistance heating, induction heating, convection heating, etc. It is inevitable to heat the inner wall of the fluidized bed, and under certain specific heating methods (such as external resistance heating), the temperature of the inner wall of the fluidized bed is the highest.
  • silicon-containing materials including monosilane
  • the raw material gas is easily decomposed on the inner wall of the fluidized bed, and the elemental silicon obtained by decomposition will be deposited on the inner wall of the fluidized bed.
  • the deposition of elemental silicon on the inner wall of the fluidized bed will cause at least three types of problems:
  • the thickness of silicon deposited on the inner wall of the fluidized bed is often uneven. This unevenness will affect the heating uniformity of the silicon-containing raw gas, making the diameter of the granular silicon products uneven.
  • the Chinese invention patent with publication number CN101318654B discloses a granular silicon production equipment, including a physically separated heating device and a reaction device.
  • the seed crystal is heated in the heating device and then transferred to the reaction device.
  • the reaction device is passed through Silicon-containing raw gas, the raw gas decomposes and deposits silicon on the surface of the higher-temperature seed crystal.
  • This patent reduces the temperature in the reaction zone by separating the heating zone from the reaction zone, thereby reducing the deposition of silicon-containing raw gas on the inner wall of the reaction zone.
  • the structure of this system is complex. In principle, it is impossible to avoid the raw material gas entering the heating zone and depositing on the high-temperature inner wall of the heating zone. There is still the problem of silicon deposition on the inner wall.
  • the Chinese invention patent with publication number CN101928001A discloses a fluidized bed equipment, which lowers the temperature of the outer wall of the fluidized bed by setting a cooling jacket on the outer wall of the fluidized bed and using an internal heating device to heat it, thereby reducing the amount of elemental silicon in the flow. Deposition on the inner wall of the bed.
  • this solution cannot avoid the deposition of elemental silicon on the internal heating device, and due to the addition of a cooling jacket, the temperature of the entire fluidized bed will be uneven and reduce the temperature. Particle size uniformity of low particle silicon products.
  • the Chinese invention patent with publication number CN101400835B discloses a method of using chlorine-containing etching gas to etch the inner wall of a fluidized bed to deposit silicon.
  • This method uses an etching gas tube that penetrates deep into the reaction zone to provide etching gas, thereby etching the inner wall of the reaction zone.
  • Deposit silicon does not drain the granular silicon product before etching, which will inevitably lead to the loss of the granular silicon product.
  • this solution only etches the deposited silicon on the inner wall of the reaction zone, ignoring the deposited silicon on the inner wall of the heating zone, and does not solve the problem of the problem of deposited silicon. Uniformity issue.
  • the Chinese invention patent with publication number CN103213989B discloses a tilted and rotating fluidized bed structure to reduce silicon deposition on the inner wall of the fluidized bed through physical methods. However, this structure will bring about the problem of poor sealing of the fluidized bed. Unable to put it into practice.
  • the metal inner wall of the fluidized bed will be exposed to the reaction gas, thereby introducing metal impurities brought by the inner wall material of the fluidized bed into the granular silicon product, greatly reducing the granular silicon
  • the quality of the product therefore, needs to provide a method that can effectively evaluate the etching progress, uniformly and accurately retain the appropriate thickness of silicon attached to the inner wall of the fluidized bed, and avoid direct contact between the raw material gas and the inner wall of the fluidized bed.
  • the present invention relates to a method for cleaning silicon formation on the inner wall of a fluidized bed, which includes: using hydrogen chloride gas of a certain purity to etch the inner wall of the fluidized bed under preset flow, temperature, and pressure conditions to produce Initial exhaust gas; discharge the initial exhaust gas from the fluidized bed; wherein, the numerical ratio between the flow rate of hydrogen chloride gas (Kg/h) and the surface area (M2) of the inner wall of the fluidized bed ranges from 0.5 to 3, and the temperature range range ranges from 400 to 1000 °C, the pressure range is 0.1Mpa to 0.2Mpa, and the purity of hydrogen chloride gas is greater than or equal to 99.5%.
  • the method of cleaning the silicon formed on the inner wall of the fluidized bed also includes: filtering the solid particles in the primary exhaust gas to obtain the middle exhaust gas; lowering the temperature of the middle exhaust gas to the recovery temperature, wherein the recovery temperature ranges from 9 to 30 °C; after lowering the temperature of the middle exhaust gas to the recovery temperature, the liquid material is collected to obtain the last exhaust gas.
  • the method of cleaning the silicon-containing inner wall of the fluidized bed also includes: detecting the content of silicon-containing gas in the initial exhaust gas and/or the middle exhaust gas at the first moment and the second moment; cleaning the inner wall of the fluidized bed at the first moment When the silicon junction process starts, the second moment is after the first moment; between the first moment and the second moment, the preset flow rate, temperature, pressure and purity of hydrogen chloride gas remain consistent.
  • the preset flow rate, temperature, pressure and purity of the hydrogen chloride gas remain constant.
  • the method of cleaning the silicon formed on the inner wall of the fluidized bed also includes: removing the silicon in the initial exhaust gas and/or the middle exhaust gas detected at the first moment.
  • the content of the silicon-containing gas is compared with the content of the silicon-containing gas in the initial exhaust gas and/or the middle exhaust gas detected at the second moment; in the trichlorosilane or silicon tetrachloride detected at the second moment.
  • the method for cleaning the silicon formed on the inner wall of the fluidized bed also includes: detecting the content of silicon-containing gas in the first exhaust gas and/or the middle exhaust gas during the third etching, and the third moment is after the second moment; the first and second The interval between moments is greater than the interval between the second and third moments.
  • the method of cleaning the silicon formed on the inner wall of the fluidized bed also includes: lowering the temperature of the initial exhaust gas and/or the middle exhaust gas to the detection temperature.
  • the detection temperature ranges from 100 to 300°C, and the detection temperature is higher than the recovery temperature; After the temperature of the etching exhaust gas drops to the detection temperature, the chlorosilane component in the gas mixture is detected.
  • the method of cleaning the silicon deposits on the inner wall of the fluidized bed also includes: before starting the operation of cleaning the silicon deposits on the inner wall of the fluidized bed, stopping the fluidized bed and emptying the granular silicon in the bed.
  • the present invention relates to a method suitable for cleaning the inner wall of a fluidized bed.
  • the fluidized bed is provided with a first etching gas inlet and a second etching gas inlet in a vertical direction.
  • the second etching gas inlet is The height is higher than the first etching inlet, and the method for cleaning the silicon on the inner wall of the fluidized bed also includes: under preset flow, temperature, and pressure conditions, simultaneously introducing a certain purity of gas into the first etching gas inlet and the second etching gas inlet.
  • Hydrogen chloride gas etches the inner wall of the fluidized bed to produce etching exhaust gas; among them, the numerical ratio of the total flow rate of hydrogen chloride gas (Kg/h) to the surface area (M2) of the inner wall of the fluidized bed ranges from 0.5 to 3, and the temperature range ranges from 400 to 1000°C, the pressure range is 0.1Mpa to 0.2Mpa, the purity of hydrogen chloride gas is greater than 99.5%; the hydrogen chloride gas flow rate at the first etching gas inlet is 1 to 4 times the hydrogen chloride gas flow rate at the second etching gas inlet.
  • hydrogen chloride gas is introduced from the second etching gas inlet along the tangential direction of the inner wall of the fluidized bed.
  • Figure 1 shows an embodiment of a silicon particle production equipment
  • Figure 2 shows an embodiment of a fluidized bed gas distribution device
  • Figure 3 shows another embodiment of a fluidized bed for producing silicon particles
  • Figure 4 is a schematic top view of the purge pipe of the fluidized bed in Figure 2;
  • Figure 5 shows another embodiment of the fluidized bed purge tube structure
  • Figure 6 shows a schematic diagram of the internal structure of the fluidized bed of Figure 2 with the top removed;
  • Figure 7 shows another embodiment of the internal structure of the fluidized bed with the top removed.
  • connection includes various connection methods, including direct connection and indirect connection, which do not require physical contact between the various parts being connected, including snap connections, screw connections, and connections without fixed devices.
  • connection methods including connection, welding, riveting and one-piece molding.
  • fit clearance includes fit relationships such as clearance fit, transition fit, interference fit or variable clearance.
  • Figure 1 shows the production equipment used to produce granular polysilicon according to the present invention.
  • the production equipment includes a fluidized bed 100, a filtering device 200, and a gas-liquid separation and recovery device 300.
  • the production equipment also includes a gas supply device (not shown in the figure).
  • the fluidized bed 100 is the core device of the entire granular silicon production equipment.
  • the fluidized bed 100 includes a bed body 101.
  • the bed body 101 is made of hard and easy-to-process materials, including carbon steel, stainless steel, ceramics, etc.
  • the bed 101 forms a space for accommodating reaction raw materials and providing a space for accommodating reaction products. After the silicon-containing raw material gas enters this space, it is heated, undergoes thermal decomposition or reduction reaction, and generates granular polysilicon in this space. When the polysilicon product reaches a certain amount, the polysilicon product will be discharged from the fluidized bed through the product discharge pipe 104. Excreted from the body.
  • the bed 101 has a certain height and its cross-section is generally circular. The circular cross-section can make the heating of the silicon-containing raw material gas more uniform and make it easier to shape during the manufacturing process.
  • the bed 101 is provided with multiple gas inlets and outlets.
  • the comprehensive air inlet 102 is located at the bottom of the bed 101, and its other end is connected to a gas supply device.
  • the gas supply device can supply various gases including raw material gas and etching gas.
  • the integrated gas inlet 102 of the type is connected to an integrated air inlet valve (not shown in the figure), and the integrated air inlet valve functions to close and/or switch the gas passage of the integrated air inlet 102 .
  • the raw material gas includes silicon-containing gases such as monosilane (SiH 4 ), silicon tetrachloride (SiCl 4 ), trichlorosilane (SiHCl 3 ), dichlorosilane (SiH 2 Cl 2 ), etc.
  • monosilane (SiH 4 ) is used as the raw material gas.
  • Monosilane can be prepared by various production processes including metal hydride method, silicon-magnesium alloy method, and trichlorosilane disproportionation method.
  • the reaction temperature in the fluidized bed can vary according to the specific raw material gas.
  • the fluidized bed heating temperature can be 600°C to 800°C.
  • heating The temperature is 650°C ⁇ 700°C.
  • the heating temperature of the trichlorosilane (SiHCl 3 ) fluidized bed may be 900°C to 1200°C.
  • the heating temperature may be 1000°C to 1050°C.
  • the gas flow rate of the silicon-containing raw material gas and the fluidizing gas is maintained at a gas flow rate of 1.1 to 4.0 Umf, but is not limited thereto. For example, it can also be 1.0 to 8.0 Umf, or 2.0 to 5.0 Umf, or 1.2 to 2.0 Umf.
  • the residence time of the silicon-containing raw gas is generally less than 12 seconds, can be less than 9 seconds, and can be less than 4 seconds.
  • 20 mol% to 80 mol% of the silicon-containing raw material gas can be used, and the rest is fluidized gas.
  • a seed crystal inlet 105 is provided at the top of the bed 101 for providing seed crystals as cores of deposited silicon into the bed.
  • the particle size of the granular silicon seed crystal is usually 50-1000 ⁇ m.
  • the particle size of the granular silicon seed crystal is 100-500 ⁇ m; and the size of the produced granular polysilicon product is usually 50-1000 ⁇ m. 500-3000 ⁇ m.
  • the particle size of granular silicon products is 800-2000 ⁇ m. The above numerical range serves only as an example and should not be regarded as a limitation on the embodiments of this patent.
  • the etching gas includes a series of chlorine-containing substances such as silicon tetrachloride (SiCl 4 ), hydrogen chloride (HCl), and chlorine gas (Cl 2 ). Using these chlorine-containing substances as etching gas can avoid the introduction of impurities other than chlorine into the gas path of the entire fluidized bed production equipment.
  • the integrated air inlet 102 is located in an area with a higher temperature inside the bed, where the raw material gas concentration is also larger. Therefore, the elemental silicon is more easily dissipated at the outlet of the integrated air inlet 102 Deposits will easily lead to poor air intake or blockage of the integrated air inlet 102.
  • the raw material gas and the etching gas share a comprehensive air inlet management, which can not only provide the etching gas to the inside of the bed to etch the elemental silicon deposited on the inner wall of the bed, but also can more fully etch the silicon on the inner wall of the bed during the etching process.
  • the elemental silicon deposited at the outlet of the integrated air inlet 102 prevents clogging of the integrated air inlet.
  • An exhaust gas outlet 103 is provided at the top of the bed 101. Since the raw material gas or etching gas in the bed 101 flows upward after being heated, providing an exhaust gas outlet at the top of the bed 101 can more completely remove the reaction exhaust gas or etching gas in the bed. The exhaust gas is discharged for the next step of treatment.
  • the concentration of the raw material gas discharged to the tail gas outlet 103 is low, the temperature there is also relatively low, and the gas flow rate is relatively low. It is faster, so the amount of elemental silicon deposited at the exhaust outlet 102 is smaller.
  • the etching gas during the etching process can already etch a small amount of elemental silicon deposited at the exhaust gas outlet 102 .
  • tail gas outlet A is used to discharge the tail gas generated during the etching process of the inner wall of the fluidized bed.
  • the tail gas outlet B is used to discharge the tail gas generated during the preparation of granular silicon. .
  • the space formed by the bed 101 is roughly divided into a heating zone 1011 and a reaction zone 1012 in the vertical direction, and the reaction zone is located above the heating zone.
  • the raw material gas or etching gas enters the space inside the bed through the integrated air inlet 102 provided at the bottom of the bed, and in the heating zone 1011 After being heated by the heating device, it moves upward to the reaction zone 1012.
  • the raw material gas fully undergoes thermal decomposition or reduction reaction in the reaction zone to produce polysilicon products, or the etching gas fully etches the entire inner wall of the bed to clean the silicon on the inner wall of the fluidized bed.
  • a gas distributor 106 is provided at the bottom of the heating zone of the bed 101.
  • the shape of the gas distributor 106 is the same as the cross-sectional shape of the bottom of the bed 101.
  • the cross section of the bottom of the heating zone of the bed 101 is circular, and the shape of the gas distributor 106 is also circular.
  • the gas distributor 106 is connected to the integrated air inlet 102 and forms a gas path.
  • a plurality of gas outlets are provided on the gas distributor 106. The raw material gas and/or etching gas enters the gas distributor 106 through the integrated air inlet 102, and then It is ejected from the air outlet of the gas distributor 106.
  • a gas distributor to redistribute the raw material gas entering the bed can make the raw material gas more uniformly distributed in the bed, making the diameter of the granular silicon product more uniform and the utilization ratio of the raw material gas higher.
  • the use of a gas distributor can directly use the raw gas as a fluidizing gas.
  • the so-called fluidizing gas functions to pass through the solid particles inside the bed from bottom to top, so that the solid particles are compressed under the pull of the fluid. An upward force is generated. When the upward force of the solid particles is greater than or equal to the gravity of the solid particles themselves, the solid silicon particles inside the bed will appear in a suspended or boiling state. The "fluidization" in the fluidized bed That's why the two characters got their name.
  • the material of the gas distributor 106 includes quartz, silicon carbide, silicon nitride or elemental silicon. Using such non-metallic materials can avoid introducing metal element impurities into the granular silicon products and improve the quality of the granular silicon products.
  • the gas distributor is provided with a plurality of openings, wherein the openings 1061 located inside the gas distributor are used for the passage of the raw material gas and/or the fluidizing gas.
  • This part The openings are far away from the inner wall of the fluidized bed, which can reduce the contact between the raw material gas and the inner wall of the fluidized bed, and reduce the deposition of elemental silicon on the inner wall of the fluidized bed.
  • the opening 1062 located at the edge of the gas distributor is used for the passage of the etching gas.
  • the opening 1062 is closer to the inner wall of the fluidized bed. After the etching gas enters the bed through 1062, it can fully contact the inner wall of the fluidized bed, thereby improving the etching effect.
  • the opening in the center of the gas distributor is used to connect the product discharge pipe 104 .
  • the bottom of the bed also includes a fluidizing gas inlet (not shown in the figure) that is independent of the integrated air inlet.
  • the gas can be selected from a variety of gases including nitrogen, argon, and helium. The principle of selecting this type of fluidizing gas is that it does not react with the raw material gas in the fluidized bed or the material components of the bed body.
  • the fluidizing gas can directly use raw material gas (including silane, chlorosilane, hydrogen chloride, etc.) or reducing gas (such as hydrogen). Although these gases participate in the reaction process, the reaction products of these gases will not be introduced. Other impurity elements.
  • the heating zone adopts induction heating.
  • a heating device 107 is provided at the bed position corresponding to the heating zone.
  • the heater 107 moves from outside to inside. They are the coil and the metal flux structure in turn.
  • an alternating current is provided to the coil to generate an alternating magnetic field.
  • the alternating magnetic field induces eddy currents in the metal magnetic flux structure, and the metal is heated under the action of the eddy current.
  • the magnetic flux structure then conducts heat to the interior of the bed.
  • no metal magnetic flux structure is provided, and an induced eddy current is directly generated in the shell of the bed to generate heat.
  • Induction heating has the characteristics of simple product structure, high thermal efficiency, and the ability to heat the silicon particles themselves.
  • the silicon seed crystal and/or silicon-containing raw material gas and/or fluidization gas are preheated to 300 ⁇ 500°C, or 350°C ⁇ 450°C, or preheated to 400°C.
  • the preheating method can be, for example, heat exchange with the reaction tail gas or conventional electric heaters, microwave heating, etc.
  • preheating the raw material gas and/or the fluidizing gas and the silicon seed crystal it is beneficial to reduce the load of the induction heating device.
  • preheating the seed crystal can also improve the conductivity of the seed crystal, which can directly generate induced eddy currents inside the seed crystal, greatly improving the heating efficiency.
  • the heater 107 can also adopt various heating methods such as thermal resistance heating, microwave heating, and radiation heating.
  • the bottom of the bed 101 adopts an inclined design, through which the granular silicon product can be more completely discharged from the product discharge pipe 104.
  • Figure 3 shows another fluidized bed structure.
  • the fluidized bed 200 includes a bed 201, and the bed 201 includes a heating zone 2011 and a reaction zone 2012.
  • a comprehensive air inlet 202, a product discharge device 204, and a fluidizing gas inlet 208 are provided at the bottom of the bed 201.
  • a seed crystal inlet 205 and an exhaust gas discharge port 203 are provided at the top of the bed 201.
  • the exhaust gas discharge port 203 can be used to discharge the exhaust gas in the normal production process and the exhaust gas generated during the etching and cleaning process of the inner wall of the fluidized bed. .
  • the cross-sectional area of the reaction zone 2012 is larger than the area of the heating zone 2011. This design can reduce the gas flow rate in the reaction zone 2012, allowing the raw material gas and/or etching gas to react more fully in the reaction zone. When the flow rate is reduced, the content of fine silicon powder in the exhaust gas can also be reduced.
  • a purge pipe 209 is provided at the bed position corresponding to the reaction zone 2012.
  • One end of the purge tube 209 is connected to the opening in the bed reaction zone, and the other end is connected to a purge and/or etching gas supply device (not shown in the figure).
  • the purge tube can provide purge gas to the inner wall of the bed and etching gas to the inner wall of the bed.
  • the purge pipe is provided with a purge valve, and the purge valve functions to close and/or switch the gas passage of the purge pipe 209 .
  • the purge gas includes various gases including nitrogen, argon, and helium.
  • the selection principle of this type of purge gas is that it does not interact with the raw material gas or bed body in the fluidized bed. Material composition reacts.
  • the purge gas can directly use hydrogen chloride or hydrogen. Although these gases participate in the reaction process with elemental silicon, the reaction products of these gases do not introduce other impurity elements, and can also avoid the fluidization of elemental silicon. Deposition on the inner walls of the bed.
  • the purge gas and the fluidizing gas are of the same composition.
  • the purge gas moves along the inner wall of the bed, which can isolate the silicon-containing reaction gas from the inner wall of the bed, thereby reducing the deposition of elemental silicon on the inner wall of the fluidized bed.
  • the etching gas includes a series of chlorine-containing substances such as silicon tetrachloride (SiCl 4 ), hydrogen chloride (HCl), and chlorine gas (Cl 2 ).
  • etching gas can avoid the introduction of impurities other than chlorine into the gas path of the entire fluidized bed production equipment.
  • the etching gas moves along the inner wall of the bed, reacts with the elemental silicon on the inner wall of the bed, and plays an etching role.
  • the gas outlet direction of the purge pipe 209 is tangent to the shell of the reaction zone.
  • the purge pipe 209 is tilted upward, and its inclination angle relative to the horizontal direction is 10 to 45°. Preferably it is 20-35°.
  • the gas ejected from the purge tube 105 can be made close to the inner wall of the bed, increasing the contact between the purge gas and/or the etching gas and the inner wall of the bed, so as to achieve the isolation effect of the purge gas and/or The etching effect of the etching gas is better; through the inclined setting, the purge and/or etching gas can spiral up along the inner wall of the bed after entering the bed through the purge tube, and fully contact the inner wall of the bed, so that The purge gas can move sufficiently in the reaction section and/or the etching lift can fully etch the silicon on the inner wall of the reaction section.
  • the axis of the air inlet direction of the purge tube and the tangent line of the air inlet have a certain angle ⁇ , and the value of ⁇ ranges from 5 to 45°.
  • two or more purge tubes are provided in the reaction zone. These purge tubes are centrally symmetrically distributed along the axis of the reaction zone to isolate the reaction gas and/or flow. During the cleaning process of silicon formation on the inner wall of the bed, purge gas and/or etching gas are introduced into each purge tube at the same time. With such an arrangement, the purge gas and/or etching gas can fully cover the entire inner wall of the fluidized bed, thereby improving the effect of isolating the reaction gas and/or etching the inner wall of the fluidized bed.
  • the inner wall of the bed corresponding to the reaction zone is provided with threads 4013, and the angle of the threads 4013 is consistent with the inclination angle of the purge tube.
  • a gas passage is formed between the threads. After the purge gas and/or etching gas is blown into the bed through the purge tube, the gas will move along the passage formed between the threads. Through the arrangement of the threaded passage, the movement path of the purge gas and/or the etching gas can be effectively restricted, so that the effect of the purge gas in isolating the reaction gas and/or etching the inner wall of the fluidized bed is better.
  • the cross-sectional width of the thread gradually decreases from the inner wall of the bed to the top of the thread, and the overall cross-section of the thread 4013 is triangular or smaller at the top and larger at the bottom. of trapezoid. Adopting such a cross-sectional shape of the thread can reduce the deposition of elemental silicon on the top of the thread, and improve the isolation effect of the purge gas and/or the etching effect of the etching gas.
  • Silicon formation on the inner wall of the fluidized bed is a gradual accumulation process. Only when the silicon formation on the inner wall of the fluidized bed reaches a certain level and may affect the heat transfer efficiency or the physical structure of the fluidized bed, it is necessary to treat the inner wall of the fluidized bed. The deposited silicon is cleaned.
  • the fluidized bed In the general production process of granular silicon, the fluidized bed usually maintains its maximum production capacity when the supply of raw materials is relatively stable and the demand for granular silicon products is relatively strong.
  • the inner wall of the fluidized bed should be etched once when the fluidized bed is running at full load for 3 to 6 months.
  • the silicon formation speed on the inner wall is also basically the same. Therefore, this type The timing of shutting down the fluidized bed for etching is also consistent with the above-mentioned 3,000-ton fluidized bed, which is also 3 to 6 months.
  • the etching gas is high-purity hydrogen chloride gas with a purity (w/w) ⁇ 99.5% 99.95%.
  • the preparation method of the high-purity hydrogen chloride gas is: mixing 31% concentrated hydrochloric acid and concentrated calcium chloride solution After entering the desorption tower, the solution is continuously heated by the desorption reboiler. The hydrogen chloride gas is stripped from the mixed solution of concentrated hydrochloric acid and calcium chloride and discharged from the top of the tower. The stripped HCl gas is then passed through the demister into the sulfuric acid for drying. process, and then dehydrate the HCl gas to finally obtain high-purity hydrogen chloride gas. This method is safer and more economical than electrolyzing sodium chloride solution to prepare hydrogen chloride gas.
  • the integrated air inlet pipe 102 provided at the bottom of the fluidized bed 101 is used to introduce high-purity hydrogen chloride gas, and the flow rate of the hydrogen chloride gas is adjusted through the pipeline regulating valve.
  • the numerical proportional relationship between the flow rate of hydrogen chloride gas (Kg/h) and the surface area of the inner wall of the fluidized bed (M 2 ) ranges from 0.5 to 3. As an optional implementation, the proportional range ranges from 1 to 1.5.
  • the inner wall surface area is specifically the surface area of the inner wall of the fluidized bed excluding the fluidized bed bottom plate.
  • the flow rate of hydrogen chloride gas is 33-200Kg/h.
  • the flow rate of hydrogen chloride gas is 60-100Kg/h.
  • the purpose of controlling the hydrogen chloride flow rate above the lower limit is to ensure the etching gas concentration in the bed, thereby ensuring the speed of the etching reaction and completing the etching process as quickly as possible.
  • an upper limit is set for the hydrogen chloride flow rate.
  • the hydrogen chloride gas will not be able to fully react with the deposited silicon on the inner wall of the fluidized bed, resulting in more waste of hydrogen chloride gas.
  • the flow rate of hydrogen chloride remains constant during the entire etching process. Since the etching object of hydrogen chloride is the deposited silicon on the inner wall of the fluidized bed, and as the etching process progresses, the area of deposited silicon on the inner wall of the fluidized bed does not change. There will be too much change, which means that the amount of reactive substances corresponding to the etching gas remains basically constant at each time point of etching. Therefore, keeping the flow rate of hydrogen chloride gas constant during the entire etching process, the control method is relatively simple, and Will not affect the entire etching process.
  • the heating power of the fluidized bed is adjusted through the power adjustment cabinet of the fluidized bed heater to maintain the temperature inside the bed at 400-1000°C.
  • the temperature range within the bed is 600-800°C.
  • the purpose of setting the lower temperature limit is to ensure the reaction rate, thereby avoiding the loss of output caused by stopping production for a long time.
  • the purpose of setting the upper temperature limit includes: on the one hand, since the heating device used in the etching process uses the original heating equipment of the fluidized bed, and the temperature used in the fluidized bed production of polysilicon is lower than that of the Siemens method, If the original heating equipment of the fluidized bed is used to provide a temperature far exceeding the temperature used for its own preparation, it will greatly increase the power burden of the heating equipment and reduce the life of the heating equipment.
  • the relationship between temperature and the reaction speed of the etching gas is not a simple linear relationship, in other words, as the temperature increases, the marginal speed of the reaction between the etching gas and the silicon deposited on the inner wall of the fluidized bed will decrease. , when the temperature is higher than 1000°C, the cost of increasing the etching speed by further increasing the temperature will increase sharply. In addition, excessively high temperatures will have unpredictable effects on the thermal reliability and chemical stability of the fluidized bed shell, which may cause certain safety hazards.
  • the pressure in the bed is maintained at 0.1Mpa ⁇ 0.2Mpa by controlling the regulating valve connected to the exhaust gas outlet.
  • a pressure value higher than 0.1Mpa can ensure the concentration of etching gas in the bed and ensure that the etching process proceeds quickly and efficiently.
  • the upper limit of the pressure value is set mainly for the safety of the fluidized bed to prevent explosion risks caused by excessive pressure.
  • High-purity hydrogen chloride enters the fluidized bed through the integrated air inlet pipe at the bottom of the fluidized bed, and reacts with the elemental silicon deposited on the inner wall of the fluidized bed to generate silane and hydrogen.
  • the main reaction formula is:
  • the chlorosilanes generated during the etching process mainly include silicon tetrachloride (SiCl 4 ), trichlorosilane (SiHCl 3 ), and dichlorosilane (SiH 2 Cl 2 ), and chlorosilane is the main component of the etching exhaust gas, except for
  • the etching exhaust gas also includes hydrogen and fine silicon powder that moves with the rising air flow.
  • hydrogen chloride gas is introduced into the integrated air inlet pipe 202 and the purge pipe 209 at the same time.
  • the total flow rate of the hydrogen chloride gas (Kg/h) and the surface area of the inner wall of the fluidized bed (M 2 ) has a numerical proportional relationship ranging from 0.5 to 3. As an optional implementation, the proportional range is from 1 to 1.5.
  • the inner wall surface area here is specifically the surface area of the inner wall of the fluidized bed excluding the fluidized bed bottom plate. For a special-shaped fluidized bed, it can be replaced by the side surface area of the cylindrical structure corresponding to the largest diameter in the horizontal section of the entire fluidized bed.
  • the flow rate of hydrogen chloride gas introduced through the integrated air inlet pipe 202 is greater than or equal to the flow rate of hydrogen chloride gas introduced through the purge pipe 209, and the ratio range is 4:1 to 1:1.
  • the hydrogen chloride gas introduced into the fluidized bed through the integrated air inlet pipe 202 enters from the bottom of the fluidized bed. It first passes through the heating zone of the fluidized bed. After the hydrogen chloride gas is heated in the heating zone 2011, it fully interacts with the deposited silicon on the inner wall 2011 of the heating zone. reaction, playing the role of etching.
  • the deposited silicon on the inner wall of the entire fluidized bed is uneven - the deposited silicon on the inner wall of the reaction zone 2012 is more than the deposited silicon in other areas of the fluidized bed, and the hydrogen chloride gas introduced from the bottom of the fluidized bed is often already exhausted when it reaches the reaction zone. After sufficient reaction, the hydrogen chloride concentration is reduced, and the deposited silicon on the inner wall of the reaction zone 2012 cannot be fully etched, resulting in the inability to fully etch the deposited silicon on the inner wall of the entire fluidized bed. At this time, the hydrogen chloride gas is replenished through the purge tube 209 provided in the reaction zone to maintain the concentration of hydrogen chloride in the reaction zone, thereby more fully etching the inner wall of the reaction zone 2012 . With this arrangement, the deposited silicon at various locations on the inner wall of the fluidized bed can be fully and uniformly etched.
  • the primary exhaust gas generated by etching is discharged from the fluidized bed through the exhaust gas outlet 103, and enters the filter device 200 connected to the exhaust gas outlet 103.
  • the components of the initial exhaust gas include chlorosilane, hydrogen and fine silicon particles.
  • the filter device 200 includes at least one set of filters, which are used to filter the primary exhaust gas containing fine silicon particles discharged from the exhaust outlet, leaving the fine silicon particles in the filter device.
  • the filtering area of the filtering device 200 is 20 to 50m 3 , and the filtering precision is 0.4 to 0.8 ⁇ m.
  • the filtering device may also be a cyclone separator.
  • the fine silicon particles filtered by the filtration device 200 can be recovered and used as seed crystals for producing granular silicon.
  • the components of the middle exhaust gas after passing through the filter device 200 are mainly chlorosilanes (mainly silicon tetrachloride and trichlorosilane) and hydrogen.
  • the silicon dust filtered by the filtering device 200 can be re-invested into the production of fluidized bed granular silicon as seed crystal raw material for the fluidized bed.
  • the gas-liquid separation and recovery device 300 is connected to the filtering device 200 .
  • the gas-liquid separation device can be a rectification tower.
  • the rectification tower takes advantage of the different boiling points of different components in the mixture or the different vapor pressures of each component at the same temperature to make the liquid phase
  • the light components are transferred to the gas phase, and the high components in the gas phase are transferred to the liquid phase, thereby achieving the purpose of gas-liquid separation.
  • the use of a distillation tower can accurately separate each substance in the mixture, and the purity of each substance is high. .
  • the gas-liquid separation and recovery device 300 includes a heat exchanger 301 and a gas-liquid separation tank 302.
  • the heat exchanger 301 is used to cool the filtered middle exhaust gas.
  • the medium exhaust gas includes chlorosilanes and hydrogen.
  • the chlorosilanes here include silicon tetrachloride (SiCl 4 ), trichlorosilane (SiHCl 3 ), dichlorosilane (SiH 2 Cl 2 ) and other chlorine- and silicon-containing gases. collectively.
  • the heat exchanger 301 reduces the temperature of the etching exhaust gas to below 30°C.
  • the main chlorosilane components including silicon tetrachloride and trichlorosilane will become liquid, and the remaining gas is the final exhaust gas, whose main component is hydrogen. Since hydrogen is non-polluting, the final exhaust gas can reach the environment After standardization, it is directly discharged into the atmosphere and can also be recycled and reused.
  • the heat exchanger 301 reduces the temperature of the etching exhaust gas to below 8°C. At this temperature, dichlorodihydrogen silicon will also become liquid (the boiling point of dichlorodihydrogen silicon is 8.2°C), which can Further improve the purity of hydrogen in the last exhaust gas.
  • the gas-liquid mixture cooled by the heat exchanger enters the gas-liquid separation tank 302.
  • the gas-liquid separation tank usually includes an inlet, a gas outlet and a liquid outlet. After the gas-liquid mixture enters the gas-liquid separation tank through the inlet, the gas and liquid are separated inside the separation tank. Separation, the separated last exhaust gas is discharged from the gas outlet, and the separated liquid is discharged from the liquid outlet.
  • the gas-liquid separation device inside the gas-liquid separation tank 302 may include various types of gas-liquid separation devices such as distributors, liquid separation plates, filters, and cyclones.
  • a heat exchanger as a gas-liquid separation and recovery device can completely separate hydrogen and chlorosilane.
  • the accuracy of separation of etching tail gas through a heat exchanger and a gas-liquid separation tank is lower than that of a distillation tower, the separated Chlorosilanes (including a mixture of silicon tetrachloride and trichlorosilane) can be directly used as raw materials for the preparation of polycrystalline silicon by the Siemens method without further separation of the individual components in the liquid mixture. Therefore, the use of heat exchangers can greatly reduce the cost of etching exhaust gas treatment, while reducing the complexity of the entire system and ensuring stable operation of the system.
  • chlorosilane easily undergoes the following two reactions with water at high temperatures:
  • the chlorosilane produced during the etching process will undergo a hydrolysis reaction to generate impurities such as silicon dioxide and orthosilicic acid, reducing the availability of the etching exhaust gas.
  • Using high-purity hydrogen chloride gas as the etching gas during the etching process can avoid the introduction of moisture during the entire etching process, ensure the purity of the etching exhaust gas, and improve the recyclability of the etching exhaust gas.
  • the existing dry tail gas recovery equipment and processes in the improved Simon process can also be used for recycling, including various tail gas recovery technologies such as pressurized condensation, gas-liquid separation, absorption, and adsorption.
  • the existing fluidized bed exhaust gas recovery equipment can be directly used for recovery without setting up a separate recovery device for etching exhaust gas.
  • the fine silicon powder in the exhaust gas is filtered out by the filter device 200, and enters the gas analysis device (not shown) provided at the rear end of the filter device 200 at the C end.
  • the gas analysis device analyzes the content of silicon-containing gas in the etching exhaust gas to determine the silicon etching condition on the inner wall of the fluidized bed. Since the gas inlet of the gas analysis device is thin, filtering out the fine silicon powder before detecting the exhaust gas components can avoid clogging of the inlet of the gas analysis device and extend the service life of the gas analysis device.
  • the etching exhaust gas can also be directly passed into the gas analysis device.
  • the fluidized bed is a 3000-ton fluidized bed
  • the high-purity hydrogen chloride gas flow is 100Kg/h
  • the reaction temperature is 1000°C
  • the reaction pressure is 0.2Mpa.
  • the silicon-containing gas components in the etching exhaust gas were analyzed by a gas analysis device. The data were: trichlorosilane 113,800 ppmv and silicon tetrachloride 277,240 ppmv.
  • the gas analysis device was used to analyze the silicon-containing gas components in the etching exhaust gas. The data were: trichlorosilane 1120ppmv and silicon tetrachloride 9260ppmv.
  • the content of trichlorosilane has been lower than one percent of the data at the beginning of etching, that is, the etching process has been completed.
  • a layer of elemental silicon protection is still retained on the inner wall of the fluidized bed.
  • This protective layer can avoid the introduction of metal or other types of impurity elements from the inner wall of the metal or ceramic fluidized bed during the production process of granular silicon, thereby improving the quality of granular silicon products.
  • the fluidized bed is a 3000-ton fluidized bed
  • the high-purity hydrogen chloride gas flow is 50Kg/h
  • the reaction temperature is 400°C
  • the reaction pressure is 0.1Mpa.
  • the silicon-containing gas components in the etching exhaust gas were analyzed by a gas analysis device. The data were: trichlorosilane 41,250 ppmv and silicon tetrachloride 115,420 ppmv.
  • the gas analysis device was used to analyze the silicon-containing gas components in the etching exhaust gas. The data were: trichlorosilane 910ppmv and silicon tetrachloride 2340ppmv.
  • the content of silicon tetrachloride has been lower than one-fiftieth of the data at the beginning of etching, that is, the etching process has been completed.
  • a layer of elemental silicon still remains on the inner wall of the fluidized bed. The protective layer.
  • a cooling device is provided between the filtering device and the gas analysis device for cooling the high-temperature exhaust gas to prevent the high-temperature exhaust gas from damaging the gas analysis device or affecting the measurement accuracy of the gas analysis device.
  • the cooling device reduces the temperature of the etching exhaust gas to below 300°C and above 100°C. Within this temperature range, the main components of the etching exhaust gas still remain in the gas state.
  • the cooling device reduces the temperature of the etching exhaust gas to the range of 80°C to 150°C, and then the gas analysis device performs sampling and detection.
  • each silicon-containing gas component in the etching exhaust gas is detected more than three times during the entire etching process, and the time interval between each detection is gradually shortened. Since the entire etching process takes a long time, usually 10 to 30 days, in the early stage of etching, the silicon on the inner wall of the fluidized bed is thicker, and the effective reaction area of the silicon on the inner wall of the fluidized bed does not change much during the etching process. When the purity, flow rate, temperature, pressure and other conditions of the hydrogen chloride gas remain unchanged, the silicon-containing gas composition in the test results will not change much. The main purpose of the test at this time is to determine whether the etching process is proceeding normally. , so at this stage, inspection can be done once a day, but it is not limited to this time.
  • the silicon-containing gas component in the etching exhaust gas needs to be detected relatively frequently.
  • the interval between inspections in the later stages of etching should be shorter than the intervals between inspections in the early stages of etching. For example, near the end of etching, inspections can be made once an hour, but detection is not limited to this time. Through such detection time interval setting, the service life of the gas analysis device can be extended while ensuring the accuracy of judging the etching degree.
  • the present invention is not limited to the specific device structures, arrangements and methods shown in the claims or description. As long as structures, steps or methods similar to those of the present invention are adopted and similar effects can be achieved, they should be considered to fall within the protection scope of the present invention. .

Abstract

一种用于生产多晶硅的流化床内壁结硅的清洁方法，包括：在预设的流量、温度、压力条件下，利用一定纯度的氯化氢气体对流化床内壁进行蚀刻，其中，氯化氢气体的流量(Kg/h)与流化床内壁的表面积(M 2)的数值比例范围为0.5至3，温度范围为400至1000℃，压力范围为0.1Mpa至0.2Mpa，氯化氢气体的纯度大于等于99.5％。该清洁方法能够高效地清洁流化床内壁结硅，同时能够有效地利用清洁过程中产生的尾气。

Description

一种清洁流化床内壁结硅的方法 技术领域
本发明涉及多晶硅制备设备与方法，特别涉及通过流化床设备制备颗粒硅的设备与方法，具体涉及去除流化床在多晶硅生产过程中内壁沉积硅的设备与方法。
背景技术
作为半导体与太阳能电池领域的基础材料，多晶硅被广泛地应用于生产包括各种电子逻辑器件、存储器件、分立器件等在内的尺寸微小却功能复杂的精密系统，更是太阳能电池板中用于光电转换的PN结的直接原料。可以这么说，当今的人类文明从很大程度上是建立在硅原子之上的。随着人类文明的进一步发展，对于高精度的电子系统的需求以及对于太阳能等清洁能源的需求更加旺盛，导致对于多晶硅的需求进一步的增长。因此，需要提供一种成本低、产量高、环境安全性好的多晶硅生产设备与工艺。
现有的生产多晶硅的工艺主要包括改良西门子法与流化床法。在现阶段，改良西门子法是最常用的一种工艺，其多晶硅产量占全球多晶硅产量的绝大多数，相比之下，流化床法是近些年来逐渐推广的工艺方法，其多晶硅产量占比正在逐年上升。
西门子法(包括改良西门子法)又可以称为氢还原法，其采用的主要设备为钟罩式反应器，主要原料为三氯氢硅与氢气。作为典型的西门子法制备多晶硅的方法，是在钟罩反应器内对直径20mm左右的多晶硅棒进行加热，使得三氯氢硅被氢气还原出来的多晶硅在硅棒表面进行沉积，从而使硅棒“长大”，当硅棒的体积达到一定程度时，取出硅棒，即能得到多晶硅产品。
西门法的典型化学反应为：
SiHCl3+H2→Si+3HCl
西门子法应用广泛，技术成熟，多晶硅产品的纯度能够做到很高，所以通常用来生产对于纯度要求更高的半导体用多晶硅产品。在西门子法中，为了避免单质硅在钟罩反应器的内壁沉积，硅棒被直接加热，钟罩外壁通常会设置冷却装置，使钟罩壁的温度远远低于硅棒的温度，减少单质硅在钟罩反应气壳体的沉积。
但是，西门子法存在着需要停机拆除长大的硅棒导致的无法连续生产问题，且多晶硅产品在下游应用时需要经过额外的粉碎步骤。
流化床法(包括硅烷流化床法)，其中，硅烷流化床法又可以称为“硅烷气热分解法”，其采用的主要设备通常被称为“流化床”，采用的原料气包括甲硅烷(SiH4)、四氯化硅(SiCl4)、三氯硅烷(SiHCl3)、二氯硅烷(SiH2Cl2)等含硅的气体，在流化床内被加热分解或被还原，产生的多晶硅在流化床内的细微硅颗粒(又被称为“籽晶”)的表面上沉积并长大，从而生产颗粒状的多晶硅产品。
硅烷流化床法典型的反应方程式为：
SiH4→Si+2H2
由于多晶硅直接沉积在籽晶的表面，而流化床内部处于流化(又称“沸腾”)状态的籽晶的有效沉积面积远大于西门子法中采用的硅棒表面的沉积面积，因此，流化床法的生产效率远大于西门子法。同时，由于含硅原料气热分解的温度较低，比如在300～400℃的温度下，含硅原料气已经开始分解。实际中，现有的流化床生产工艺的含硅原料气的加热温度通常在500～700℃，其耗能也相对较低。因此，流化床法制备颗粒硅的工艺在近年来被广泛推广使用。
但现有的流化床工艺设备仍然存在一定的问题：由于需要对流化床内的含硅原料气进行整体的加热，现有的包括电阻加热、感应加热、对流加热等各种加热方式都不可避免地对流化床内壁进行加热，并且在某些特定的加热方式(如外置电阻加热)下，流化床内壁的温度最高，在这种情况下，包括甲硅烷在内的含硅原料气就容易在流化床内壁上进行分解，分解所得的单质硅将会在流化床内壁上进行沉积。单质硅在流化床内壁沉积将会带来至少三类问题：
其一，随着流化床内壁沉积硅的厚度变厚，且由于多晶硅的电阻大且导热系数小，大部分加热方式下的加热效率将受到极大的影响，为了维持含硅原料气的热分解温度，不得不提高加热设备的功率，从而增加了能耗。
其二，流化床内壁沉积硅的厚度往往是不均匀的，这种不均匀性会影响含硅原料气的加热均匀性，使得颗粒硅产品的直径不均匀。
其三，在流化床内壁沉积硅到达一定的厚度时，部分单质硅块将会从流化床内壁上脱落，砸伤或砸坏流化床结构，造成极大的安全隐患，掉落的大块硅块容易堵塞进料管。
现有的流化床工艺与设备往往无法避免流化床内壁沉积硅的问题，因此，在流化床运行一定周期后，需要停机以对流化床内壁的沉积硅进行清除。已有技术针对清除流化床内壁沉积硅的问题提出了一些方案：
公开号为CN101318654B的中国发明专利公开了一种颗粒硅生产设备，包括物理上分隔的加热装置与反应装置，籽晶在加热装置中被加热，然后被传送至反应装置中，反应装置中通入含硅原料气，原料气在温度较高的籽晶表面分解并沉积硅。该专利通过将加热区与反应区分隔的方式，降低了反应区内的温度，从而减少了含硅原料气在反应区内壁沉积。但该套系统结构复杂，从原理上无法避免原料气进入加热区并在加热区的高温内壁上进行沉积，仍然存在着内壁沉积硅的问题。
公开号为CN101928001A的中国发明专利公开了一种流化床设备，其通过在流化床外壁设置冷却夹套并采用内部加热装置加热的方式，降低流化床外壁的温度，减少单质硅在流化床内壁的沉积。但该方案无法避免单质硅在内部加热装置上的沉积，并且，由于加入了冷却夹套，会使得整个流化床温度不均匀，降 低颗粒硅产品的粒径均匀性。
公开号为CN101400835B的中国发明专利公开了一种利用含氯蚀刻气体蚀刻流化床内壁沉积硅的方法，该方法利用一个深入至反应区的蚀刻气体管提供蚀刻气体，从而蚀刻在反应区内壁的沉积硅。但该方案在蚀刻之前没有排空颗粒硅产品，必然会导致颗粒硅产品的损耗，并且该方案仅针对反应区内壁的沉积硅进行蚀刻，忽略了加热区内壁的沉积硅，没有解决沉积硅不均匀性的问题。
公开号为CN103213989B的中国发明专利公开了一种倾斜且旋转的流化床结构，以通过物理的方法减少流化床内壁的硅沉积，但该结构将会带来流化床密封性差的问题，无法付诸实践。
一方面，需要提供一种解决流化床内壁结硅的设备和/或方法，以均匀地除去流化床内壁结硅，同时，该方法需要快速地去除流化床内壁结硅，减少停机带来的停产损失，且原料、设备成本较低。
另一方面，如果对流化床内壁蚀刻过于彻底，将会使得流化床的金属内壁暴露于反应气体，从而给颗粒硅产品引入流化床内壁材料带来的金属杂质，极大地降低颗粒硅产品的品质，因此，需要提供一种能够有效评估蚀刻进度的方法，均匀且精确地保留适当厚度的、附着在流化床内壁的硅，避免原料气与流化床内壁直接接触。
与此同时，需要提供一种流化床结构，能够在颗粒硅生产过程中减少单质硅在流化床内壁的沉积。
为了解决以上问题，提出本发明。
发明内容
在一个实施方案中，本发明涉及一种清洁流化床内壁结硅的方法，包括：在预设的流量、温度、压力条件下，利用一定纯度的氯化氢气体对流化床内壁进行蚀刻，产生初排尾气；将初排尾气从流化床排出；其中，氯化氢气体的流量(Kg/h)与流化床内壁的表面积(M2)的数值比例范围为0.5至3，温度范围为400至1000℃，压力范围为0.1Mpa至0.2Mpa，氯化氢气体的纯度大于等于99.5％。
进一步的，清洁流化床内壁结硅的方法还包括：过滤初排尾气中的固体颗粒，得到中排尾气；将中排尾气的温度降至回收温度，其中，回收温度的范围为9至30℃；将中排尾气的温度降至回收温度后，收集液体物质，得到末排尾气。
进一步的，清洁流化床内壁结硅的方法还包括：在第一时刻与第二时刻分别检测初排尾气和/或中排尾气中含硅气体的含量；第一时刻为清洁流化床内壁结硅过程开始的时刻，第二时刻在第一时刻之后；在第一时刻与第二时刻，预设的流量、温度、压力以及氯化氢气体的纯度保持一致。
进一步的，在整个清洁流化床内壁结硅的过程中，预设的流量、温度、压力以及氯化氢气体的纯度保持恒定。
进一步的，清洁流化床内壁结硅的方法还包括：将第一时刻所检测到的初排尾气和/或中排尾气中的 含硅气体的含量与第二时刻所检测到的初排尾气和/或中排尾气中的含硅气体的含量进行比较；在第二时刻所检测到的三氯氢硅或四氯化硅中任意一个物质成分为第一时刻所检测到的对应物质成分的1/100至1/50时，停止蚀刻过程。
进一步的，清洁流化床内壁结硅的方法还包括：在第三蚀刻检测初排尾气和/或中排尾气中含硅气体的含量，第三时刻在第二时刻之后；第一与第二时刻的间隔大于第二与第三时刻的间隔。
进一步的，清洁流化床内壁结硅的方法还包括：将初排尾气和/或中排尾气的温度降至检测温度，检测温度的范围为100至300℃，检测温度高于回收温度；将蚀刻尾气的温度降至检测温度之后，检测气体混合物中氯硅烷的成分。
进一步的，清洁流化床内壁结硅的方法还包括：在清洁流化床内壁结硅的操作开始之前，将流化床停机并排空床体内的颗粒硅。
在另一个实施方案中，本发明涉及一种适用于流化床内壁清洁的方法，流化床在竖直方向上设置有第一蚀刻气体入口以及第二蚀刻气体入口，第二蚀刻气体入口的高度高于第一蚀刻入口，清洁流化床内壁结硅的方法还包括：在预设的流量、温度、压力条件下，在第一蚀刻气体入口与第二蚀刻气体入口同时通入一定纯度的氯化氢气体对流化床内壁进行蚀刻，产生蚀刻尾气；其中，氯化氢气体的总流量(Kg/h)与流化床内壁的表面积(M2)的数值比例范围为0.5至3，温度范围为400至1000℃，压力范围为0.1Mpa至0.2Mpa，氯化氢气体的纯度大于99.5％；第一蚀刻气体入口处的氯化氢气体流量与第二蚀刻气体入口处的氯化氢气体流量的1至4倍。
进一步的，从第二蚀刻气体入口处沿着流化床内壁的切线方向通入氯化氢气体。
附图说明
在附图的图示中通过举例而非限制的方式示出了实施方案，在附图中类似的附图标号指示类似的元件。应当指出的是，在本公开中提到“一”或“一个”的实施方案未必是同一的实施方案。
图1示出了硅颗粒生产设备的一个实施例；
图2示出了流化床气体分配装置的一个实施例；
图3示出了用于生产硅颗粒的流化床的另一个实施例；
图4为图2的流化床的吹扫管的俯视示意图；
图5示出了流化床吹扫管结构的另一个实施例；
图6示出了图2的流化床去除顶部后的内部结构示意图；
图7示出了流化床去除顶部后的内部结构的另一个实施例。
具体实施方式
在这个部分中，我们将参考附图来解释本发明的若干实施方案。每当在实施方案中描述的部件的形状、相对位置和其它方面未明确限定时，本发明的范围并不仅局限于所示出的部件，所示出的部件仅用于例证的目的。另外，虽然阐述了许多细节，但应当理解，本发明的一些实施方案可在没有这些细节的情况下被实施。在其他情况下，未详细示出熟知的结构和技术，以免模糊对本描述的理解。
本文中所使用的术语仅是为了描述特定实施方案而并非旨在对本发明进行限制。空间相关术语，诸如“在……之下”、“在……下方”、“下”、“在……上方”、“上”等可在本文中用于描述的方便，以描述一个元件或特征与另外一个或多个元件或一个或多个特征的关系，如在附图中示出的。应当理解，空间相对术语旨在涵盖除了在附图中所示的取向之外的设备使用或操作过程中的不同取向。例如，如果附图中的设备被翻转，则被描述为在其他元件或特征“下方”或“之下”的元件然后可被取向成在其他元件或特征“上方”。因此，示例性术语“在……下方”可涵盖在……上方和在……下方这两个取向。设备可以另外的方式进行取向(例如，旋转90度或以其他取向)，并且在本文中使用的空间相对描述词被相应地解释。
如本文所用，单数形式“一个”、“该”等旨在同样包括复数形式，除非上下文另外指出。应当进一步理解，术语“包括”和/或“包含”限定特征、步骤、操作、元件、和/或部件的存在，但不排除一个或多个其他特征、步骤、操作、元件、部件和/或其集合的存在或添加。
本文所使用的术语“或”和“和/或”应被解释为包含性的或意指任意一个或任意组合。因此，“A、B或C”或“A、B和/或C”指“以下中的任意一种：A；B；C；A和B；A和C；B和C；A、B和C。”只有当元素、功能、步骤或行为的组合在某种程度上是固有地相互排斥时，才会出现该定义的例外情况。
本文中所称的“连接”包括直接连接与间接连接在内的各种连接方式，不要求被连接的各个部位之间存在物理上的接触，包括了卡扣连接、螺丝连接、无固定装置的连接、焊接、铆接、一体成型在内的各种具体连接方式。在部件配合的场合下，配合间隙包括了间隙配合、过渡配合、过盈配合或者可变间隙等配合关系。
本文针对流量、压力、温度、纯度等各类化学化工参数所称的“一致”或“恒定”并不要求被比较的两个参数在数值上完全一致，如果被比较的两个参数围绕近似的数值且在一定范围内上下波动，亦应当被看作是“一致”或者“恒定”。
如图1所示为本发明用于生产颗粒多晶硅的生产设备。生产设备包括流化床100、过滤装置200、气液分离回收装置300，除此之外，生产设备还包括气体供应装置(图中未示出)。
流化床
流化床100是整个颗粒硅生产设备的核心装置。流化床100包括床体101，床体101采用质地较硬且便于加工的材料，包括碳钢、不锈钢、陶瓷等。床体101形成一个空间，用于容纳反应原料并提供容纳反应产物的空间。含硅原料气进入该空间后被加热，进行热分解或者还原反应，并在该空间内生成颗粒状的多晶硅，当多晶硅产品达到一定数量后，多晶硅产品将通过产品排出管道104从流化床床体中排出。床体101具有一定的高度，其横截面大体呈圆形，圆形的截面能够使得针对含硅原料气的加热更加均匀，在制造过程中也更容易成型。
床体101设置有多个气体的出入口，其中，综合进气口102位于床体101的底部，其另一端与气体供应装置相连，气体供应装置可以供应包括原料气与蚀刻气体在内的各种类型的气体综合进气口102连接有综合进气阀(图中未示出)，综合进气阀起到关闭和/或切换综合进气口102的气体通路的作用。其中，原料气包括甲硅烷(SiH4)、四氯化硅(SiCl4)、三氯硅烷(SiHCl3)、二氯硅烷(SiH2Cl2)等在内的含硅的气体，在本实施例中使用甲硅烷(SiH4)作为原料气。甲硅烷可以采用金属氢化物法、硅镁合金法、三氯氢硅歧化法在内的各种生产工艺进行制备。
流化床内的反应温度可根据具体的原料气有所差别，对于甲硅烷热分解流化床而言，其流化床加热温度可为600℃～800℃，作为可选的实施方式，加热温度为650℃～700℃。而三氯硅烷(SiHCl3)流化床的加热温度可为900℃～1200℃，作为可选的实施方式，加热温度为1000℃～1050℃。
含硅原料气体和流态化气体的进气量维持在气体流速为1.1～4.0Umf，但不限于此，例如还可以为1.0～8.0Umf，或2.0～5.0Umf，或1.2～2.0Umf。相应的，含硅原料气的停留时间一般少于12s，还可以少于9s，更可以少于4s。含硅原料气体的比例没有任何限制，作为可选的方式，可以采用例如20mol％～80mol％的含硅原料气体，剩下的为流态化气体。
在床体101的顶部设置有籽晶加入口105，用于向床体内部提供作为沉积硅内核的籽晶。在流化床反应器中，颗粒硅籽晶的粒径通常在50～1000μm，作为可选的实施方式，颗粒硅籽晶的粒径为100～500μm；而生产出的粒状多晶硅产品的尺寸通常500～3000μm，作为可选的实施方式，颗粒硅产品的粒径为800～2000μm。以上数值范围仅起到举例的作用，不应当被看作为对本专利实施例的限制。
蚀刻气体包括四氯化硅(SiCl4)、氯化氢(HCl)和氯气(Cl2)等一系列含氯物质。采用这些含氯物质作为蚀刻气体，能够避免在整个流化床生产设备的气体通路中引入除氯以外的其他杂质。
在颗粒硅产品的生产过程中，综合进气口102位于床体内部温度较高的区域，该处的原料气体浓度也较大，因此，单质硅更为容易地在综合进气口102的出口处沉积，容易导致综合进气口102进气不畅或者发生堵塞。在本实施方案中，原料气与蚀刻气体共用一个综合进气口管理，不仅能够向床体内部提供蚀刻气体以蚀刻床体内壁上沉积的单质硅，还能够在蚀刻过程中较为充分地蚀刻在综合进气口102出口位置沉积的单质硅，避免综合进气口的堵塞。
床体101的顶部设置有尾气出口103，由于床体101内的原料气或蚀刻气体经过加热后都向上流动，在床体101的顶部设置尾气出口能够较为完整地将床体内的反应尾气或者蚀刻尾气排出，从而进行下一步的处理。在多晶硅的生产过程中，由于原料气体在床体101内已经经过了充分的反应，因此，排至尾气出口103处的原料气的浓度较低，该处的温度也相对较低且气体流速相对较快，所以，在尾气排出口102处所沉积的单质硅数量较少。在当前的工艺与设备中，在蚀刻过程中的蚀刻气体已经能够蚀刻尾气排出口102处沉积的少量单质硅。
在本实施例中，床体的顶部设置两个尾气排出口，尾气排出口A用于排出流化床内壁蚀刻过程中产生的尾气，尾气排出口B用于排出颗粒硅制备过程中产生的尾气。
床体101所形成的空间在竖直方向上大体被分为加热区1011与反应区1012，反应区位于加热区的上方。在多晶硅的生产或者流化床内壁的清洁过程中，从气体的运动路径来看，原料气或蚀刻气体通过设置在床体底部的综合进气口102进入床体内部的空间，在加热区1011被加热装置加热后向上运动至反应区1012，原料气在反应区充分的进行热分解或者还原反应，产生多晶硅产物，或者蚀刻气体整个床体内壁充分的进行蚀刻，清洁流化床内壁结硅。
如图1、图2所示，作为一种实施方式，在床体101的加热区的底部位置设置有气体分布器106，气体分布器106的形状与床体101底部的横截面形状相同，在本实施例中，床体101加热区的底部位置的横截面为圆形，气体分布器106的形状亦为圆形。气体分布器106与综合进气口102相连并形成气体的通路，在气体分布器106上设置有多个出气孔，原料气和/或蚀刻气体通过综合进气口102进入气体分布器106，然后从气体分布器106的出气孔上喷出。采用气体分布器将进入床体内的原料气重新分布，能够使得原料气在床体内的分布更加均匀，能够使得颗粒硅产品的直径更加均匀且原料气的利用比例越高。另一方面，采用气体分布器的设置能够直接将原料气作为流化气体，所谓流化气体的作用是自下而上穿过床体内部的固体颗粒，使得固体颗粒在流体的拉力的作用下产生向上的作用力，在固体颗粒的向上作用力大于或等于固体颗粒本身的重力的情况下，床体内部的固体颗粒硅就会呈现悬浮或沸腾的状态，流化床中的“流化”两字即因此得名。气体分布器106的材料包括石英、碳化硅、氮化硅或单质硅，采用这样的非金属材料，能够避免给颗粒硅产品引入金属元素杂质，提高颗粒硅产品的质量。
如图2所示，作为一种实施方式，气体分布器上设置有多个开孔，其中，位于气体分布器内部的开孔1061用于原料气体和/或流化气体的通路，这部分的开孔远离流化床体内壁，能够减小原料气与流化床内壁的接触，减少流化床内壁的单质硅沉积。位于气体分布器边缘的开孔1062用于蚀刻气体的通路，开孔1062更加贴近流化床内壁，蚀刻气体通过1062进入床体后能够充分地与流化床内壁接触，提高蚀刻的效果。气体分布器中央的开孔用于连接产品排出管道104。
作为可选的实施方式，床体的底部还包括独立于综合进气口的流化气体进入口(图中未示出)，流化 气体可以选择氮气、氩气、氦气在内的多种气体，这一类流化气体的选用原则是不与流化床内的原料气或床体的材料成分反应。作为可选的实施方式，流化气体可以直接选用原料气(包括硅烷、氯硅烷、氯化氢等)或还原气体(如氢气)，虽然这些气体参与反应过程，但这些气体的反应产物并不会引入其他杂质元素。
作为一种实施方式，加热区采用感应加热的方式，在采用感应加热的场合，加热区所对应的床体位置设置有加热装置107，作为一种可选的实施方式，加热器107由外向内依次为线圈、金属磁通结构，在加热时，向线圈提供交变电流，以产生交替变化的磁场，交替变化的磁场在金属磁通结构中感应出涡电流，在涡电流的作用下加热金属磁通结构，进而向床体内部传导热量。作为可选的实施方式，不设置金属磁通结构，直接在床体的外壳中产生感应涡流电流进而产生热量。另外，由于硅本身具有一定的导电性，在流化床内处于流化状态的硅颗粒内部亦有可能通过感应形成电流，从而对硅颗粒本身进行加热。感应加热具有产品结构简单、热效率高、能够对硅颗粒本身进行加热的特点。
作为可选的实施方式，硅籽晶和/或含硅原料气体和/或流化气体进入流化床反应器前被预热至300～500℃，或350℃～450℃，或预热至400℃。其预热方式可采用例如与反应尾气换热或常规的电加热器、微波加热等方式。通过预热原料气和/或流化气和硅籽晶，有利于减小感应加热装置的负荷。在采用感应加热的场合下，对籽晶进行预热也能够提高籽晶的导电性，从而能够在籽晶内部直接产生感应涡流，极大地提高了加热的效率。
作为可选的实施方式，加热器107还可以采用热电阻加热、微波加热、辐射加热等各种加热方式。
作为可选的实施方式，床体101的底部采用倾斜设计，通过这样的设计能够更完全地从产品排出管道104中排出颗粒硅产品。保护气体吹扫
图3示出了另一种流化床体结构，该实施例中的流化床200包括床体201，床体201包括加热区2011与反应区2012。在床体201的底部设置有综合进气口202、产品排出装置204、流化气体进口208。在床体201的顶部设置有籽晶加入口205，尾气排出口203，其中，尾气排出口203能够同时用于排出正常生产过程中的尾气以及对流化床内壁进行蚀刻清洁过程中产生的尾气。
反应区2012的横截面积大于加热区2011的面积，采用这样的设计，能够降低反应区2012内的气体流速，让原料气和/或蚀刻气体更加充分地在反应区内进行反应。流速降低的情况下，也能够减少尾气中的细硅粉含量。
在本实施例中，反应区2012对应的床体位置设置有吹扫管209。吹扫管209一端与床体反应区上的开孔相连接，另一端与吹扫和/或蚀刻气体供给装置(图中未示出)相连接。吹扫管既可以向床体内壁提供吹扫气体，也可以向床体内壁提供蚀刻气体。
吹扫管设置有吹扫阀门，吹扫阀门起到关闭和/或切换吹扫管209的气体通路的作用。
在提供吹扫气体的情况下，吹扫气体包括氮气、氩气、氦气在内的多种气体，这一类吹扫气体的选用原则是不与流化床内的原料气或床体的材料成分反应。作为可选的实施方式，吹扫气体可以直接选用氯化氢或氢气，虽然这些气体参与与单质硅的反应过程，但这些气体的反应产物并不会引入其他杂质元素，也能够避免单质硅在流化床内壁的沉积。可选择的，吹扫气体与流化气体采用相同的成分。
吹扫气体沿着床体内壁运动，能够将含硅反应气与床体内壁隔离，从而减少在流化床内壁的单质硅沉积。
蚀刻气体包括四氯化硅(SiCl4)、氯化氢(HCl)和氯气(Cl2)等一系列含氯物质。采用这些含氯物质作为蚀刻气体，能够避免在整个流化床生产设备的气体通路中引入除氯以外的其他杂质。蚀刻气体沿着床体内壁运动，与床体内壁的单质硅反应，起到蚀刻的作用。
如图3、图4所示，吹扫管209的出气方向与反应区的壳体相切，同时，吹扫管209且向上倾斜设置，其相对于水平方向的倾斜角度为10～45°，优选为20～35°。通过相切的设置，能够使得吹扫管105内喷出的气体紧贴床体的内壁，增加吹扫气体和/或蚀刻气体与床体内壁的接触，使得吹扫气体的隔离效果和/或蚀刻气体的蚀刻效果更好；通过倾斜的设置，能够使得吹扫和/或蚀刻气体在通过吹扫管进入床体后，能够沿着床体内壁螺旋上升，充分地与床体内壁接触，使得吹扫气体能够充分地在反应段进行运动和/或蚀刻提起能够针对反应段的内壁结硅进行充分的蚀刻。
作为可选的实施方式，如图5所示，吹扫管进气方向的轴线与进气口的切线具有一定的夹角θ，θ的取值范围为5～45°。通过将吹扫管相对切线方向适当倾斜，能够降低吹扫管的制造难度。同时，由于吹扫管与切线方向的角度设置，通过吹扫管进入流化床体内部的气体仍然能够在床体内壁上产生较大的切向分立，驱动吹扫气体沿着床体内壁移动。
如图3～4所示作为可选的实施方式，在反应区设置有两个以上的吹扫管，这些吹扫管沿着反应区的轴线呈中心对称分布，在隔离反应气体和/或流化床内壁结硅的清洁过程中，各吹扫管同时通入吹扫气体和/或蚀刻气体。采用这样的设置，能够让吹扫气体和/或蚀刻气体充分地布满整个流化床内壁，提高隔离反应气体的效果和/或蚀刻流化床内壁的效果。
如图6所示，在另一个实施例中，反应区对应的床体内壁设置有螺纹4013，螺纹4013的角度与吹扫管的倾斜角度保持一致。螺纹之间形成气体的通路，在吹扫气体和/或蚀刻气体经过吹扫管被吹入床体后，气体将沿着螺纹之间形成的通路运动。通过螺纹通路的设置，能够有效地限制吹扫气体和/或蚀刻气体的运动路径，让吹扫气体的隔离反应气体的效果和/或蚀刻流化床内壁的效果更好。
如图7所示，作为可选的实施方式，就螺纹4013截面的形状而言，螺纹截面宽度自床体内壁向螺纹顶部呈现逐渐变小的趋势，螺纹4013截面整体呈三角形或上小下大的梯形。采用这样的螺纹截面形状，能够减小单质硅在螺纹顶端的沉积，提高吹扫气体的隔离效果和/或蚀刻气体的蚀刻效果。
流化床内壁蚀刻过程
流化床内壁结硅是一个逐渐累积的过程，只有在流化床内壁结硅到达一定的严重程度且可能影响传热效率或者影响流化床物理结构的情况下，才需要对流化床内壁的沉积硅进行清理。
在颗粒硅的一般生产过程中，在原料的提供相对稳定且颗粒硅产品需求相对旺盛的情况下，流化床通常会保持其最大的生产能力。对于年产3000吨的流化床而言，一般而言，在流化床满负载运行3～6个月时就应当对流化床内壁进行一次蚀刻。对于其他具有更大或者更少产量的流化床而言，由于不同大小的流化床的反应温度、原料的浓度等都保持一致，其内壁的结硅速度也基本一致，因此，这种类型流化床停机蚀刻的时机也与上述3000吨流化床保持一致，也为3～6个月。
在对流化床内壁进行除硅操作时，首先需要将流化床停机并排空床体内的全部颗粒硅。将床体内的颗粒硅全部排空能够避免蚀刻气体过度蚀刻颗粒硅产品，避免造成产品的浪费。同时，排空颗粒硅后能够完整地暴露流化床的内壁，从而对流化床内壁的沉积硅进行更加完整的蚀刻。
在本实施例中，蚀刻气体为高纯氯化氢气体，其纯度(w/w)≥99.5％99.95％，该高纯氯化氢气体的制备方法为：将31％的浓盐酸与浓氯化钙溶液混合后进入解析塔，溶液不断的通过解析再沸器加热，氯化氢气体从浓盐酸与氯化钙混合溶液中汽提出来并从塔顶排出，然后将汽提出的HCl气体通过除雾器进入硫酸干燥工序，接着对HCl气体进行脱水，最终得到高纯氯化氢气体。该方法相较于电解氯化钠溶液制备氯化氢气体更安全和经济，特别的，通过该种工艺制备氯化氢气体的工艺与设备已经在西门子法中被广泛的应用，因此，只需要利用现有的设备即可制备氯化氢气体以对流化床内壁沉积硅进行蚀刻，无需额外的增加设备与成本。
在清洁流化床内壁的蚀刻过程中，利用设置在流化床101底部的综合进气管102通入高纯度氯化氢气体，通过管线调节阀调解氯化氢气体的流量。氯化氢气体的流量(Kg/h)与流化床内壁表面积(M2)的数值比例关系范围为：0.5～3，作为可选的实施方式，该比例范围为1～1.5。这里的内壁表面积具体是除去流化床底板的流化床内壁的表面积，对于异形流化床而言，可以用整个流化床的水平截面中最大直径对应的圆柱结构的侧面表面积代替。针对本实施例所用的3000吨产量的流化床而言，氯化氢气体的流量为33～200Kg/h，作为可选的实施方式，氯化氢气体的流量为60～100Kg/h。将氯化氢流量控制在下限值之上的目的是保证床体内的蚀刻气体浓度，从而保证蚀刻反应的速度，能够尽快的完成蚀刻的过程。同时，对氯化氢流量设定一个上限，如果超过该上限，氯化氢气体将无法与流化床内壁的沉积硅进行充分的反应，会造成较多的氯化氢气体的浪费。作为可选的实施方式，氯化氢的流量在整个蚀刻过程中保持恒定，由于氯化氢的蚀刻对象为流化床内壁的沉积硅，而随着蚀刻进程的推进，流化床内壁沉积硅的面积并不会有太大的变化，也就意味着蚀刻气体对应的反应物质的量在蚀刻的各个时间点都基本保持恒定，因此，保持氯化氢气体在整个蚀刻过程中的流量恒定，控制方式相对简单，也不会影响整个蚀刻过程。
通过流化床加热器的调功柜调节流化床的加热功率，使床体内的温度维持在400～1000℃，作为可选的实施方式，床体内的温度范围为600～800℃。设定温度下限的目的在于保证反应速率，从而避免由于长时间停止生产带来的产量损失。设置温度上限的目的包括：一方面，由于蚀刻过程所采用的加热装置利用的是流化床原本的加热设备，而流化床生产多晶硅的过程所采用的温度相比于西门子法的温度低，如果利用流化床原本的加热设备来提供远超于其本身制备所采用的温度，将会极大的增加加热设备的功率负担，降低加热设备的寿命。另外，由于温度与蚀刻气体的反应速度之间的关系并不是单纯的线形关系，换句话说，在温度升高的过程中，蚀刻气体与流化床内壁沉积硅的反应的边际速度将会递减，在温度高于1000℃的情况下，通过进一步提高温度来提高蚀刻速度所需要投入的成本将会急剧增加。此外，过高的温度会给流化床的壳体的热可靠性与化学稳定性带来无法预计的影响，从而有可能带来一定的安全隐患。
通过控制连接至尾气排出口的调节阀使床体内的压力维持在0.1Mpa～0.2Mpa。压力值高于0.1Mpa能够保证床体内的蚀刻气体的浓度，确保蚀刻过程快速、高效地进行。设定压力值的上限则主要是从流化床的安全性考虑，防止过高的压力带来的爆炸隐患。
高纯度氯化氢通过流化床底部的综合进气管进入流化床内，与沉积在流化床内壁的单质硅进行反应，生成硅烷与氢气，其主要的反应式为：
HCl+Si→SiHxCLy+H2
其中，在蚀刻过程中生成的氯硅烷主要包括四氯化硅(SiCl4)、三氯硅烷(SiHCl3)、二氯硅烷(SiH2Cl2)，且氯硅烷是蚀刻尾气的主要成分，除此之外，蚀刻尾气还包括氢气以及随着上升的气流而运动的细硅粉。
如图3所示，在本实施例的蚀刻过程中，在综合进气管202与吹扫管209同时通入氯化氢气体，氯化氢气体的总流量(Kg/h)与流化床内壁表面积(M2)的数值比例关系范围为：0.5～3，作为可选的实施方式，该比例范围为1～1.5。这里的内壁表面积具体是除去流化床底板的流化床内壁的表面积，对于异形流化床而言，可以用整个流化床的水平截面中最大直径对应的圆柱结构的侧面表面积代替。其中，通过综合进气管202通入的氯化氢气体流量大于等于通过吹扫管209通入的氯化氢气体的流量，其比值范围为4:1～1:1。经过综合进气管202通入流化床的氯化氢气体从流化床的底部进入，其首先经过流化床的加热区，氯化氢气体在加热区2011被加热后，与加热区内壁2011的沉积硅充分反应，起到蚀刻的作用。由于整个流化床内壁的沉积硅不均匀——反应区2012内壁的沉积硅多余流化床其他区域的沉积硅，而从流化床底部通入的氯化氢气体在到达反应区时，往往都已经经过了充分的反应，使氯化氢浓度降低，无法充分地蚀刻反应区2012内壁的沉积硅，导致无法对整个流化床内壁的沉积硅进行充分的蚀刻。此时，通过设置在反应区的吹扫管209补充氯化氢气体，以维持反应区内的氯化氢的浓度，从而对反应区2012的内壁进行更加充分的蚀刻。采用这样的设置，能够对流化床内壁各个位置的沉积硅都进行充分且均匀的蚀刻。
蚀刻尾气回收
参考图1，蚀刻产生的初排尾气通过尾气排出口103排出流化床，进入与尾气排出口103相连接的过滤装置200中，初排尾气的成分包括氯硅烷、氢气以及细微硅颗粒。在本实施例中，过滤装置200包括至少一组滤网，滤网用于将尾气排出口中排出的带有细微硅颗粒的初排尾气进行过滤，在过滤装置内留下细微硅颗粒。可选的，过滤装置200的过滤面积为20～50m3，过滤精度为0.4～0.8μm。作为可选的实施方式，过滤装置还可以是旋风分离器。经过过滤装置200过滤所得的细微硅颗粒可以回收，并用作生产颗粒硅的籽晶。在利用HCl蚀刻流化床内壁结硅的蚀刻过程中，通过过滤装置200后的中排尾气成分主要是氯硅烷(主要为四氯化硅与三氯氢硅)以及氢气。通过过滤装置200过滤得到的硅粉尘可以作为流化床的籽晶原料重新投入到流化床颗粒硅的生产中。
气液分离回收装置300与过滤装置200相连接。作为可选的实施方式，气液分离装置可以是精馏塔，精馏塔利用混合物中不同组分的沸点不同，或在同一温度下各组分的蒸气压不同的特点，使液相中的轻组分转移至气相，并使气相中的高组分转移至液相中，从而实现气液分离的目的，采用精馏塔能够准确地分离混合物中的各个物质，且各个物质的纯度较高。
在本实施例中，气液分离回收装置300包括换热器301与气液分离罐302。换热器301用于将经过过滤后的中排尾气进行冷却。中排气体包括氯硅烷与氢气，这里的氯硅烷是包括四氯化硅(SiCl4)、三氯硅烷(SiHCl3)、二氯硅烷(SiH2Cl2)等含氯且含硅气体的统称。由于氯硅烷的沸点较低，比如作为主要成分的四氯化硅的沸点为57.6℃、三氯氢硅的沸点为31.8℃，换热器301将蚀刻尾气的温度降至30℃以下，在该温度下，包括四氯化硅与三氯氢硅在内的主要氯硅烷成分都会成为液态，剩余的气体为末排尾气，其主要成分为氢气，由于氢气无污染，末排尾气可以在达到环境标准后直接排入大气中，也可以回收再利用。作为可选的实施方式，换热器301将蚀刻尾气的温度降至8℃以下，在该温度下，二氯二氢硅也将成为液态(二氯二氢硅的沸点为8.2℃)，能够进一步提高末排尾气中氢气的纯度。
经过换热器冷却后的气液混合物进入气液分离罐302，气液分离罐通常包括进口、气体出口与液体出口，气液混合物通过进口进入气液分离罐后在分离罐内部进行气体与液体的分离，分离得到的末排尾气从气体出口排出，分离得到的液体从液体出口排出。作为可选的实施方式，气液分离罐302内部的气液分离装置可以包括分配器、分液板、过滤器、旋风分离器等各种类型的气液分离装置。
采用换热器作为气液分离回收装置，能够将氢气与氯硅烷进行完整的分离，虽然通过换热器与气液分离罐对蚀刻尾气进行分离的精度低于采用精馏塔，但分离出来的氯硅烷(包括四氯化硅与三氯氢硅的混合物)可以直接作为西门子法制备多晶硅的原料，而无需对液体混合物中的各个成分进行进一步的分离。因此，采用换热器能够极大地降低蚀刻尾气处理的成本，同时降低了整个系统的复杂程度，保证了系统的稳定运行。
另外，由于氯硅烷容易在高温下与水进行下述两个反应：
SiHCl3+2H2O＝SiO2+3HCl+H2
SiCl4+4H2O＝H4SiO4↓+4HCl↑
也就是说，如果系统中出现了较多的水分，蚀刻过程中产生的氯硅烷将会发生水解反应，生成二氧化硅与原硅酸等杂质，降低蚀刻尾气的可用性。在蚀刻的过程中采用高纯度氯化氢气体作为蚀刻气体，能够避免在整个蚀刻过程中引入水分，保证蚀刻尾气的纯度，提高蚀刻尾气的可回收利用性。
作为可选的实施方式，还可以采用现有的改良西门法中的干法尾气回收设备与工艺进行回收，包括加压冷凝、气液分离、吸收、吸附等各项尾气回收技术。作为可选的实施方式，直接采用现有的流化床的尾气回收设备进行回收，无需单独设置蚀刻尾气的回收装置。
蚀刻进程的判断
蚀刻尾气通过尾气排出管103排出后，经过过滤装置200过滤掉尾气中的细硅粉，在C端进入设置在过滤装置200后端的气体分析装置(未示出)。气体分析装置分析蚀刻尾气中含硅气体的含量，从而判断流化床内壁结硅蚀刻的情况。由于气体分析装置的气体入口较细，在检测尾气成分之前过滤掉细硅粉能够避免气体分析装置的入口堵塞，延长气体分析装置的使用寿命。作为可选的实施方式，蚀刻尾气也可以直接通入气体分析装置中。
在第一个实施例中，流化床为3000吨流化床，高纯氯化氢气体流量为100Kg/h,反应温度为1000℃，反应压力为0.2Mpa。在蚀刻开始阶段，通过气体分析装置分析蚀刻尾气中的各含硅气体成分，其数据为：三氯氢硅113800ppmv、四氯化硅277240ppmv。在蚀刻后期，通过气体分析装置分析蚀刻尾气中的各含硅气体成分，其数据为：三氯氢硅1120ppmv、四氯化硅9260ppmv。在该情况下，三氯氢硅的含量已经低于蚀刻开始蚀刻的数据的百分之一，即认为已经完成了蚀刻的过程，此时，在流化床内壁上仍然保留一层单质硅保护层，该保护层能够避免在颗粒硅的生产过程中从金属或陶瓷的流化床内壁引入金属或其他类型的杂质元素，提高颗粒硅产品的质量。
在另一个实施例中，流化床为3000吨流化床，高纯氯化氢气体流量为50Kg/h,反应温度为400℃，反应压力为0.1Mpa。在蚀刻开始阶段，通过气体分析装置分析蚀刻尾气中的各含硅气体成分，其数据为：三氯氢硅41250ppmv、四氯化硅115420ppmv。在蚀刻后期，通过气体分析装置分析蚀刻尾气中的各含硅气体成分，其数据为：三氯氢硅910ppmv、四氯化硅2340ppmv。在该情况下，四氯化硅的含量已经低于蚀刻开始蚀刻的数据的五十分之一，即认为已经完成了蚀刻的过程，此时，在流化床内壁上仍然保留一层单质硅保护层。
作为可选的实施方式，在过滤装置与气体分析装置之间设置有冷却装置，用于冷却高温的尾气，避免高温尾气损坏气体分析装置或者影响气体分析装置的测量精度。冷却装置使蚀刻尾气的温度降至300℃以下且100℃以上，在该温度范围内，蚀刻尾气的主要成分都仍然保持气体的状态。作为可选的实施方式， 冷却装置使蚀刻尾气的温度降至80℃～150℃的范围，而后再由气体分析装置进行取样、检测。
作为可选的实施方式，在整个蚀刻过程中对蚀刻尾气中的各含硅气体成分进行三次以上的检测，各次检测的时间间隔逐渐缩短。由于整个蚀刻过程的时间较长，通常需要10～30天的时间，在蚀刻初期，流化床内壁结硅较厚，在蚀刻过程中流化床内壁结硅的有效反应面积变化不大，在氯化氢气体的纯度、流量、温度、压力等条件保持不变的情况下，检测结果中的含硅气体成分不会有太大的改变，此时检测的主要目的在于判断蚀刻过程是否在正常的进行，因此在这个阶段，可以一天一检，但并不以该时间为限。
在蚀刻后期，由于需要通过蚀刻的程度来判断是否需要终止蚀刻过程，因此需要相对频繁地检测蚀刻尾气中的含硅气体成分。在蚀刻后期的各次检测间隔时间要短于蚀刻初期的各次检测间隔，例如，在接近蚀刻终止的阶段，可以一小时一检，但并不以该时间检测为限。通过这样的检测时间间隔设置，能够延长气体分析装置的使用寿命的同时保证了蚀刻程度的判断精度。
本发明并不限于权利要求或说明书所示的特定装置结构、布置和方法，只要采用了与本发明相类似的结构、步骤或者方法且能够实现类似的效果，都应当认为属于本发明的保护范围。

Claims (10)

  1. 一种清洁流化床内壁结硅的方法，包括：
    在预设的流量、温度、压力条件下，利用一定纯度的氯化氢气体对流化床内壁进行蚀刻，产生初排尾气；
    将所述初排尾气从所述流化床排出；
    其中，所述氯化氢气体的流量(Kg/h)与流化床内壁的表面积(M2)的数值比例范围为0.5至3，所述温度范围为400至1000℃，所述压力范围为0.1Mpa至0.2Mpa，所述氯化氢气体的纯度大于等于99.5％。
  2. 根据权利要求1所述的方法，其特征在于：
    所述方法还包括：
    过滤初排尾气中的固体颗粒，得到中排尾气；
    将中排尾气的温度降至回收温度，其中，所述回收温度的范围为9至30℃；
    将所述中排尾气的温度降至回收温度后，收集液体物质，得到末排尾气。
  3. 根据权利要求2所述的方法，其特征在于：
    所述方法还包括：
    在第一时刻与第二时刻分别检测初排尾气和/或中排尾气中含硅气体的含量，
    所述第一时刻为清洁流化床内壁结硅过程开始的时刻，所述第二时刻在所述第一时刻之后，在所述第一时刻与所述第二时刻，所述预设的流量、温度、压力以及氯化氢气体的纯度保持一致。
  4. 根据权利要求3所述的方法，其特征在于：
    在整个清洁流化床内壁结硅的过程中，所述预设的流量、温度、压力以及氯化氢气体的纯度保持恒定。
  5. 根据权利要求3所述的方法，其特征在于：
    所述方法还包括：
    将第一时刻所检测到的初排尾气和/或中排尾气中的含硅气体的含量与第二时刻所检测到的初排尾气和/或中排尾气中的含硅气体的含量进行比较，
    在第二时刻所检测到的三氯氢硅或四氯化硅中任意一个物质成分为第一时刻所检测到的对应物质成分的1/100至1/50时，停止所述蚀刻过程。
  6. 根据权利要求5所述的方法，其特征在于：
    所述方法还包括：
    在第三蚀刻检测初排尾气和/或中排尾气中含硅气体的含量，所述第三时刻在所述第二时刻之后；
    所述第一与第二时刻的间隔大于所述第二与第三时刻的间隔。
  7. 根据权利要求3至6所述的方法，其特征在于：
    所述方法还包括：
    将初排尾气和/或中排尾气的温度降至检测温度，所述检测温度的范围为100至300℃，所述检测温度高于所述回收温度；
    将蚀刻尾气的温度降至检测温度之后，检测气体混合物中氯硅烷的成分。
  8. 根据权利要求1至6所述的方法，其特征在于：
    所述方法还包括：
    在清洁流化床内壁结硅的操作开始之前，将所述流化床停机并排空床体内的颗粒硅。
  9. 一种适用于流化床内壁清洁的方法，所述流化床在竖直方向上设置有第一蚀刻气体入口以及第二蚀刻气体入口，第二蚀刻气体入口的高度高于第一蚀刻入口，
    所述方法包括：
    在预设的流量、温度、压力条件下，在第一蚀刻气体入口与第二蚀刻气体入口同时通入一定纯度的氯化氢气体对流化床内壁进行蚀刻，产生蚀刻尾气；
    其中，所述氯化氢气体的总流量(Kg/h)与流化床内壁的表面积(M2)的数值比例范围为0.5至3，所述温度范围为400至1000℃，所述压力范围为0.1Mpa至0.2Mpa，所述氯化氢气体的纯度大于99.5％；
    所述第一蚀刻气体入口处的氯化氢气体流量与第二蚀刻气体入口处的氯化氢气体流量的1至4倍。
  10. 根据权利要求10所述的方法，其特征在于：
    从第二蚀刻气体入口处沿着所述流化床内壁的切线方向通入氯化氢气体。
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CN101400835A (zh) * 2006-06-15 2009-04-01 韩国化学研究院 应用流化床反应器连续制备多晶硅的方法
CN102333585A (zh) * 2008-11-05 2012-01-25 赫姆洛克半导体公司 通过利用四氯硅烷减少壁上沉积的流化床反应器生产硅
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CN105229198A (zh) * 2013-05-16 2016-01-06 瓦克化学股份公司 制造多晶硅的反应器和去除所述反应器的部件上的含硅层的方法
CN114308947A (zh) * 2020-09-30 2022-04-12 中国科学院微电子研究所 多晶硅生产设备的清洗方法、清洗装置及多晶硅生产设备
CN219424369U (zh) * 2022-08-03 2023-07-28 江苏中能硅业科技发展有限公司 一种流化床

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