Cleaning method for the chassis of electronic-grade polysilicon reduction furnace

Abstract

This invention discloses a method for cleaning the chassis of an electronic-grade polysilicon reduction furnace, including initial chassis cleaning, chassis etching and passivation, and deep chassis cleaning. Initial chassis cleaning includes removing dust and impurities from the surface of the chassis to be cleaned. Chassis etching and passivation includes creating a closed space between the chassis and a sealing structure, so that the surface to be cleaned is located within the closed space; and cleaning the polysilicon polymer on the surface to be cleaned within the closed space. Deep chassis cleaning includes removing the sealing structure and washing the surface to be cleaned. According to this invention's method for cleaning the chassis of an electronic-grade polysilicon reduction furnace, the use of initial chassis cleaning, chassis etching and passivation, and deep chassis cleaning to clean the polysilicon polymer on the chassis avoids the use of grinding methods to clean the polysilicon polymer, preventing metal impurities from entering the electronic-grade polysilicon production system, thereby improving the quality of the polysilicon product.

Description

Technical Field

[0001] This invention relates to the field of polysilicon technology, and in particular to a method for cleaning the chassis of an electronic-grade polysilicon reduction furnace. Background Technology

[0002] The chassis of a polysilicon reduction furnace is typically made of a material that is heat-resistant, corrosion-resistant, and has high mechanical strength. Because the internal environment of the reduction furnace is extremely hot and chemical reactions occur, the requirements for the material are quite stringent. Based on available information, the main body of the furnace is generally made of stainless steel. This is because stainless steel can withstand high temperatures and also effectively reduces the risk of contamination to the product (polysilicon).

[0003] As a key component of the reduction furnace, the chassis, considering its direct contact with high temperatures and potential exposure to chemical corrosion, will likely be made of materials such as stainless steel or other special alloys to ensure its structural stability and corrosion resistance at high temperatures. Furthermore, to enhance cooling and thermal efficiency, the chassis may be designed with a double-layer structure and include a cooling water circulation system, with insulation material potentially filling the space between the inner and outer layers. However, the specific chassis material selection will need to be determined based on the actual production process and design requirements.

[0004] In the production process of electronic-grade polysilicon reduction system, materials are deposited on silicon core carriers in the reduction furnace. The deposited byproducts may include silicon compounds, graphite particles, and other impurities formed under high-temperature reaction conditions, which need to be removed during the cleaning and maintenance phase at the end of each production cycle.

[0005] Currently, the main methods for cleaning residual polymer on the reduction furnace chassis are manual or mechanical grinding. Metal impurities generated after grinding will remain on the chassis. In subsequent polysilicon production processes, these metal impurities will be introduced into the production system, thus affecting the quality of polysilicon products. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a chassis cleaning method for an electronic-grade polysilicon reduction furnace, which can prevent metallic impurities from entering the electronic-grade polysilicon production system, thereby improving the quality of polysilicon products.

[0007] A method for cleaning the chassis of an electronic-grade polysilicon reduction furnace according to an embodiment of the present invention includes: initial chassis cleaning, wherein the initial chassis cleaning includes removing dust and impurities from the surface of the chassis to be cleaned; chassis corrosion and passivation, wherein the chassis corrosion and passivation includes: constructing a closed space with the chassis through a sealing structure so that the surface to be cleaned is located within the closed space; cleaning the polysilicon polymer on the surface to be cleaned within the closed space, wherein cleaning the polysilicon polymer on the surface to be cleaned within the closed space includes: introducing a first cleaning solvent into the closed space and causing the first cleaning solvent to corrode the polysilicon polymer on the surface to be cleaned for a first preset time, the first cleaning solvent including ammonium bifluoride solution; introducing a second cleaning solvent into the closed space and causing the second cleaning solvent to clean the surface to be cleaned for a second preset time to remove the corroded polysilicon polymer and residual first cleaning solvent from the surface to be cleaned; introducing a first drying gas into the closed space to remove the residual second cleaning solvent from the surface to be cleaned and to dry the surface to be cleaned; and deep chassis cleaning, wherein the deep chassis cleaning includes: removing the sealing structure and cleaning the surface to be cleaned.

[0008] According to the present invention, the chassis cleaning method of the electronic-grade polysilicon reduction furnace uses initial chassis cleaning to collect dust and impurities on the surface to be cleaned, chassis corrosion passivation and deep chassis cleaning to corrode the polysilicon polymer and form a protective film on the surface to be cleaned. This avoids the need to use grinding to clean the polysilicon polymer and prevents metal impurities from entering the electronic-grade polysilicon production system, thereby improving the quality of polysilicon products.

[0009] According to some embodiments of the present invention, after introducing the first dry gas into the enclosed space, the method further includes: introducing an acidic solvent into the enclosed space to form a protective film on the cleaned surface; the process of introducing the acidic solvent into the enclosed space to form the protective film on the cleaned surface includes: allowing the acidic solvent to contact the chassis for a third preset time to form the protective film on the cleaned surface; introducing an alkaline solvent into the enclosed space and allowing the alkaline solvent to react with the acidic solvent for a fourth preset time to neutralize the acidic solvent; introducing a third cleaning solvent into the enclosed space and allowing the third cleaning solvent to clean the surface of the protective film for a fifth preset time to remove the residual acidic and alkaline solvents in the enclosed space.

[0010] According to some embodiments of the present invention, after the third cleaning solvent cleans the surface of the protective film for a fifth preset time, the process further includes: detecting the pH value of the third cleaning solvent at the outlet of the enclosed space using pH test paper; when the pH value does not meet the preset pH value, continuing to inject the third cleaning solvent into the enclosed space; and when the pH value meets the preset pH value, ending the cleaning process with the third cleaning solvent.

[0011] According to some embodiments of the present invention, after detecting the pH value of the third cleaning solvent at the outlet of the enclosed space using pH test paper, the method further includes: introducing a second drying gas into the enclosed space to remove the residual third cleaning solvent from the surface to be cleaned and to dry the surface to be cleaned.

[0012] According to some embodiments of the present invention, the removal of dust and impurities from the surface to be cleaned of the chassis includes: sucking up the dust and impurities from the surface to be cleaned by vacuuming; and removing the residual dust and impurities from the surface to be cleaned by a fourth cleaning solvent.

[0013] According to some embodiments of the present invention, removing residual dust and impurities from the surface to be cleaned by the fourth cleaning solvent includes wiping the surface to be cleaned with a wiping device dipped in the fourth cleaning solvent.

[0014] According to some embodiments of the present invention, before cleaning the polycrystalline silicon polymer on the surface to be cleaned within the enclosed space, the method further includes: introducing a fifth cleaning solvent into the enclosed space, and allowing the fifth cleaning solvent to clean the surface to be cleaned for a sixth preset time.

[0015] According to some embodiments of the present invention, cleaning the surface to be cleaned includes: removing particulate impurities from the surface to be cleaned with a sixth cleaning solvent; removing residual sixth cleaning solvent from the surface to be cleaned with a seventh cleaning solvent; removing residual seventh cleaning solvent from the surface to be cleaned with a third drying gas; and drying the surface to be cleaned.

[0016] According to some embodiments of the present invention, removing particulate impurities from the surface to be cleaned by the sixth cleaning solvent includes wiping the surface to be cleaned with a wiping device dipped in the sixth cleaning solvent; removing residual sixth cleaning solvent from the surface to be cleaned by the seventh cleaning solvent includes wiping the surface to be cleaned with a wiping device dipped in the seventh cleaning solvent.

[0017] According to some embodiments of the present invention, after removing the residual seventh cleaning solvent from the surface to be cleaned by the third drying gas and drying the surface to be cleaned, the method further includes: detecting the surface to be cleaned by an ultraviolet lamp to detect whether there are particulate impurity fluorescent spots on the surface to be cleaned; when there are no particulate impurity fluorescent spots on the surface to be cleaned, the chassis cleaning is completed; when there are particulate impurity fluorescent spots on the surface to be cleaned, the chassis deep cleaning is circulated.

[0018] According to some embodiments of the present invention, the sealing structure includes: a sealing cover having a cavity with one open end, the chassis being located at the opening to form the closed space between the sealing cover and the chassis, a fixing bracket and an inlet and an outlet communicating with the closed space being provided on the outer peripheral wall of the sealing cover, the fixing bracket being used to fix the sealing cover, and valves being provided on both the inlet and the outlet; a sealing ring being located between the sealing cover and the chassis to seal the assembly gap between the sealing cover and the chassis; and an exhaust vent plug, one of the exhaust vent plugs being... The end is located inside the exhaust port of the chassis to seal the exhaust port. The sealing cover is provided with multiple first fixing members, and the other end of the exhaust port plug is fixedly connected to the first fixing members. Electrode protection cover: one end of the electrode protection cover is placed on the outer periphery of the electrode of the chassis. The sealing cover is provided with multiple second fixing members, and the other end of the electrode protection cover is fixedly connected to the second fixing members. Nozzle protection cover: one end of the nozzle protection cover is placed on the outer periphery of the nozzle of the chassis. The sealing cover is provided with multiple third fixing members, and the other end of the nozzle protection cover is fixedly connected to the third fixing members.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0021] Figure 1 This is a schematic flowchart of a chassis cleaning method for an electronic-grade polysilicon reduction furnace according to an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of a sealing cover according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the exhaust port plug according to an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of an electrode protective cover according to an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of a nozzle protective cover according to an embodiment of the present invention.

[0026] Figure label:

[0027] 10. Sealing cover; 11. Liquid inlet; 12. Liquid outlet; 13. Fixing bracket; 14. First fixing component; 15. Second fixing component; 16. Third fixing component; 17. Opening; 18. Cavity;

[0028] 21. Exhaust port plug; 211. First external thread; 22. Electrode protective cover; 221. Second external thread; 222. First protective cover; 23. Nozzle protective cover; 231. Third external thread; 232. Second protective cover. Detailed Implementation

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0032] The following is for reference. Figures 1-4A method for cleaning the chassis of an electronic-grade polysilicon reduction furnace according to an embodiment of the present invention is described.

[0033] The chassis cleaning method for an electronic-grade polysilicon reduction furnace according to an embodiment of the present invention includes three stages: initial chassis cleaning, chassis corrosion and passivation, and deep chassis cleaning.

[0034] Preliminary chassis cleaning includes removing dust and impurities from the chassis surfaces to be cleaned, and initially collecting any dust or impurities floating on these surfaces. For example, the dust or impurities may be silicon powder remaining on the chassis surfaces during the production of electronic-grade polysilicon reduction systems. This silicon powder can be removed using a mobile vacuum cleaner or a central vacuum cleaner, and can also be collected at the same time.

[0035] In related technologies, polycrystalline silicon polymers on the surface to be cleaned are cleaned by manual or mechanical grinding. However, metallic impurities generated after grinding remain on the chassis, which can then be introduced into the electronic-grade polycrystalline silicon production system, thus affecting the quality of the polycrystalline silicon products. Therefore, this application proposes chassis corrosion passivation.

[0036] Chassis corrosion passivation includes creating an enclosed space between the chassis and a sealing structure, such that the surface to be cleaned is located within the enclosed space. For example, the sealing structure may include a sealing cover 10, with the chassis located at an opening 17 of the sealing cover 10, creating an enclosed space between the chassis and the sealing cover 10.

[0037] Chassis corrosion passivation also includes cleaning polycrystalline silicon polymers on surfaces to be cleaned within enclosed spaces.

[0038] Cleaning polycrystalline silicon polymer on a surface to be cleaned within an enclosed space includes: introducing a first cleaning solvent into the enclosed space, which increases the contact area and contact time between the first cleaning solvent and the polycrystalline silicon polymer, allowing the polycrystalline silicon polymer to be immersed in the first cleaning solvent, and increasing the efficiency of the first cleaning solvent in corroding the polycrystalline silicon polymer. The first cleaning solvent can chemically corrode the polycrystalline silicon polymer, avoiding the use of abrasive methods to clean the polycrystalline silicon polymer, preventing metallic impurities from entering the electronic-grade polycrystalline silicon production system, and thus improving the quality of polycrystalline silicon products. The first cleaning solvent corrodes the polycrystalline silicon polymer on the surface to be cleaned for a first preset time, and the first cleaning solvent can circulate and clean the polycrystalline silicon polymer within the first preset time; for example, the first preset time is greater than or equal to 30 minutes, and the first cleaning solvent can be a strong acid-weak base salt, such as ammonium bifluoride solution, with the ammonium bifluoride solution being a 30%-50% concentration ammonium bifluoride solution.

[0039] A second cleaning solvent is introduced into the enclosed space to remove the etched polycrystalline silicon polymer and residual first cleaning solvent from the surface to be cleaned. The second cleaning solvent can circulate within the enclosed space, so that it carries the etched polycrystalline silicon polymer out of the enclosed space, and also carries the residual first cleaning solvent out of the enclosed space, thereby increasing the efficiency of the second cleaning solvent in cleaning the etched polycrystalline silicon polymer and residual first cleaning solvent.

[0040] The second cleaning solvent is used to clean the surface to be cleaned for a second preset time, during which it can circulate. For example, the second preset time is greater than or equal to 30 minutes. The second cleaning solvent can be ultrapure water with a resistivity of not less than 18 megohms, to carry away the etched polycrystalline silicon polymer and residual first cleaning solvent from the enclosed space. It should be noted that ultrapure water is chosen because electronic-grade polycrystalline silicon reduction systems require a high-quality environment. Using ultrapure water does not affect the environment of the electronic-grade polycrystalline silicon reduction system, ensuring its stability during the reduction reaction and thus guaranteeing the quality of the electronic-grade polycrystalline silicon.

[0041] Of course, it is understandable that the second cleaning solvent can also be ordinary water, deionized water, distilled water, etc., or a liquid that can neutralize strong acid and weak base salts can be selected according to actual needs, so as to better clean the first cleaning solvent.

[0042] A first drying gas is introduced into the enclosed space to remove residual second cleaning solvent from the surface to be cleaned and to dry the surface. The first drying gas can also blow away any residual second cleaning solvent in the enclosed space, keeping the surface dry. For example, the first drying gas can be nitrogen with a purity of not less than 99.9999%. Nitrogen with a purity of not less than 99.9999% is commonly referred to as grade VI high-purity nitrogen or ultrapure nitrogen, and it has wide applications in industrial production and scientific research. This extremely high-purity nitrogen is mainly obtained through purification processes using air separation devices, such as PSA (Pressure Swing Adsorption) technology, membrane separation technology, or cryogenic distillation, ensuring that the content of other impurity gases such as oxygen, hydrogen, carbon dioxide, and moisture is extremely low. In the semiconductor manufacturing industry, high-purity nitrogen is commonly used in processes such as chemical vapor deposition, etching, and cleaning. Based on this application, it can be applied to electronic-grade polysilicon reduction systems. In the above-mentioned process, ammonium bifluoride solution is used to etch the polysilicon polymer, that is, the polysilicon polymer is detached from the chassis through a chemical reaction. Therefore, using nitrogen with a purity of not less than 99.9999% can not only effectively clean the surface to be cleaned, but also ensure that the chassis will not be affected when used in electronic-grade polysilicon reduction systems.

[0043] Of course, helium or other gases can also be used as the first drying gas.

[0044] For example, chassis corrosion passivation also includes: introducing an acidic solvent into an enclosed space to form a protective film on the cleaned surface. By placing the chassis surface to be cleaned within an enclosed space, the acidic solvent can be introduced, increasing the contact time and area between the solvent and the surface, thus improving the corrosion efficiency of the solvent. The acidic solvent can further corrode the polysilicon polymer, removing it from the chassis. Furthermore, the solvent can form a protective film on metal chassis materials such as stainless steel, reducing the corrosiveness of polysilicon polymer deposits on the chassis during subsequent polysilicon production.

[0045] Chassis deep cleaning includes: removing the sealing structure and cleaning the surface of the protective film. Cleaning the surface of the protective film on the chassis can remove dust and impurities from the surface of the protective film, so as to further clean the chassis.

[0046] During the deep cleaning of the chassis, the sealing structure needs to be removed first, and the protective film on the surface to be cleaned needs to be removed.

[0047] In a specific example, refer to Figure 2 The sealed structure has an inlet 11 and an outlet 12. A first cleaning solvent can be introduced into the enclosed space through the inlet 11. The first cleaning solvent reacts with the polycrystalline silicon polymer on the surface to be cleaned within the enclosed space, removing the polycrystalline silicon polymer from the surface. Both the first cleaning solvent after reaction and any unreacted solvent can flow out of the enclosed space through the outlet 12. A second cleaning solvent can be introduced into the enclosed space through the inlet 11. The second cleaning solvent carries away the first cleaning solvent and polycrystalline silicon polymer within the enclosed space through the outlet 12. A first drying gas can be introduced into the enclosed space through the inlet 11. The first drying gas blows out any remaining second cleaning solvent from the enclosed space through the outlet 12. An acidic solvent can be introduced into the enclosed space through the inlet 11. The acidic solvent reacts chemically with the chassis within the enclosed space to form a protective film on the chassis. Any remaining acidic solvent can flow out of the enclosed space.

[0048] According to the present invention, the chassis cleaning method of the electronic-grade polysilicon reduction furnace uses initial chassis cleaning to collect dust and impurities on the surface to be cleaned, chassis corrosion passivation and deep chassis cleaning to corrode the polysilicon polymer and form a protective film on the surface to be cleaned. This avoids the need to use grinding to clean the polysilicon polymer and prevents metal impurities from entering the electronic-grade polysilicon production system, thereby improving the quality of polysilicon products.

[0049] Optionally, each time the chassis is cleaned using the above method, it is not necessary to introduce acidic solvent into the enclosed space each time to form a protective film on the surface of the chassis to be cleaned. This is because, once formed, the protective film will not fail during a few reduction reactions in the electronic-grade polysilicon reduction furnace, nor during cleaning of the chassis using the above method after each reduction reaction in the electronic-grade polysilicon reduction furnace. Therefore, it is not necessary to construct a protective film on the chassis each time. For example, after ten electronic-grade polysilicon reduction reactions in the electronic-grade polysilicon reduction furnace, acidic solvent is added during chassis cleaning to form a protective film on the surface of the chassis to be cleaned. That is, the protective film formation process occurs once every ten electronic-grade polysilicon reduction reaction cycles. Of course, it can be understood that the protective film formation process can also occur once every five, six, seven, eight, or nine electronic-grade polysilicon reduction reaction cycles; this application does not impose any limitations.

[0050] According to some embodiments of the present invention, with reference to Figure 1 The process involves introducing an acidic solvent into a closed space to form a protective film on the cleaned surface. This includes allowing the acidic solvent to contact the chassis for a third preset time, ensuring sufficient contact time for the solvent to fully react chemically with the surface and form a complete protective film. For example, the third preset time is 'a', satisfying 5 min ≤ a ≤ 15 min.

[0051] After the acidic solvent has been in contact with the chassis for a third preset time, an alkaline solvent is introduced into the enclosed space to neutralize the acidic solvent. The acidic and alkaline solvents can react chemically to form a neutral solvent, reducing the continued corrosion of the chassis by residual acidic solvent in the enclosed space and facilitating the removal of any remaining acidic solvent. The alkaline solvent then reacts with the acidic solvent within a fourth preset time, ensuring a sufficient amount of alkaline solvent is introduced into the enclosed space and allowing enough time for the alkaline and acidic solvents to react fully, forming a neutral solution. For example, the fourth preset time is b, satisfying 4 min ≤ b ≤ 8 min.

[0052] After introducing an alkaline solvent into the enclosed space, a third cleaning solvent is then introduced to remove any residual acidic, alkaline, and neutral solvents. This third cleaning solvent carries these solvents out of the enclosed space, effectively cleaning the chassis. The third cleaning solvent cleans the protective film surface for a predetermined time (e.g., 30 minutes or more). This ensures that the third cleaning solvent carries away as much of the residual acidic, alkaline, and neutral solvents as possible from the enclosed space. For example, the predetermined time can be 30 minutes or more. The third cleaning solvent can be ultrapure water with a resistivity of at least 18 megohms. Ultrapure water carries away the acidic, alkaline, and neutral solvents from the enclosed space, ensuring that the solution remaining in the enclosed space is ultrapure water.

[0053] In a specific example, refer to Figure 2 The sealed structure has an inlet 11 and an outlet 12. Alkaline solvent can be introduced into the enclosed space through the inlet 11. The alkaline solvent can react chemically with the acidic solvent in the enclosed space to form a neutral solvent. The neutral solvent, as well as any unreacted alkaline and acidic solvents, can flow out of the enclosed space through the outlet 12. A third cleaning solvent can be introduced into the enclosed space through the inlet 11. This third cleaning solvent carries away the acidic, neutral, and alkaline solvents in the enclosed space through the outlet 12.

[0054] According to some embodiments of the present invention, with reference to Figure 1 After the third cleaning solvent cleans the surface of the protective film for a fifth preset time, the process also includes: detecting the pH value of the third cleaning solvent at the outlet 12 of the enclosed space using pH test paper.

[0055] When the pH value does not meet the preset pH value, the pH value of the third cleaning solvent at the outlet 12 does not meet the standard, and there is residual acidic or alkaline solvent in the third cleaning solvent at the outlet 12. That is, there is still residual acidic or alkaline solvent in the closed space. Continue to inject the third cleaning solvent into the closed space so that the third cleaning solvent can carry out the acidic or alkaline solvent in the closed space.

[0056] When the pH value meets the preset pH value, the pH value of the third cleaning solvent at the outlet 12 has reached the standard. The third cleaning solvent at the outlet 12 does not carry acidic or alkaline solvents, that is, there are no acidic or alkaline solvents in the closed space, and the cleaning with the third cleaning solvent ends.

[0057] For example, the preset pH value can be 7.

[0058] According to some embodiments of the present invention, with reference to Figure 1A second drying gas is introduced into the enclosed space to remove the residual third cleaning solvent from the surface to be cleaned and to dry the surface. The second drying gas can blow away the residual third cleaning solvent in the enclosed space, keeping the surface to be cleaned dry. For example, the second drying gas can be nitrogen with a purity of not less than 99.9999%, which can quickly dry the residual third cleaning solvent on the surface to be cleaned. According to some embodiments of the present invention, refer to... Figure 1 Removing dust and impurities from the chassis surface to be cleaned includes: sucking up the dust and impurities from the surface to be cleaned by vacuuming, which can collect the dust and impurities from the surface to be cleaned into the vacuum cleaner.

[0059] The fourth cleaning solvent removes residual dust and impurities from the surface to be cleaned, further eliminating these residues and ensuring complete removal. For example, the fourth cleaning solvent can be ultrapure water with a resistivity of not less than 18 megohms, which can effectively remove residual dust and impurities from the surface.

[0060] According to some embodiments of the present invention, with reference to Figure 1 The removal of residual dust and impurities on the surface to be cleaned by the fourth cleaning solvent includes wiping the surface to be cleaned with a wiping device dipped in the fourth cleaning solvent. For example, the wiping device can be a lint-free cloth with a lint-free cloth rating of 100 or higher.

[0061] In a specific example, wiping the surface to be cleaned by using a wiping tool dipped in the fourth cleaning solvent includes: using multiple wiping tools dipped in the fourth cleaning solvent to wipe the surface to be cleaned; wiping the surface to be cleaned with one wiping tool dipped in the fourth cleaning solvent until the color of the wiping tool changes; replacing it with a new wiping tool dipped in the fourth cleaning solvent to wipe the surface to be cleaned; until the wiping tool does not change color after wiping the surface to be cleaned, that is, all the dust and impurities on the surface to be cleaned have been wiped away.

[0062] According to some embodiments of the present invention, with reference to Figure 1 Before cleaning the polycrystalline silicon polymer on the surface to be cleaned within the enclosed space, the process includes: introducing a fifth cleaning solvent into the enclosed space to pre-treat the surface and remove dust and impurities; and ensuring the fifth cleaning solvent cleans the surface for a sixth preset time. Cleaning the surface within the enclosed space for this sixth preset time ensures complete removal of impurities. For example, the sixth preset time can be greater than or equal to 30 minutes, and the fourth cleaning solvent can be ultrapure water with a resistivity of not less than 18 megohms, which can remove residual dust and impurities from the surface.

[0063] In a specific example, the sealing structure has an inlet 11 and an outlet 12. The fifth cleaning solvent can be introduced into the closed space through the inlet 11, and the fifth cleaning solvent can carry the dust and impurities on the surface to be cleaned out of the closed space through the outlet 12.

[0064] According to some embodiments of the present invention, with reference to Figure 1 Cleaning the surface to be cleaned includes: removing dust and impurities from the surface to be cleaned using a sixth cleaning solvent, which can further remove residual dust and impurities from the surface to be cleaned; for example, the sixth cleaning solvent can be an isopropanol solution, and the isopropanol solution is of UPS grade or higher.

[0065] The seventh cleaning solvent removes the residual sixth cleaning solvent from the surface to be cleaned, thereby improving the cleanliness of the surface. For example, the seventh cleaning solvent can be ultrapure water with a resistivity of not less than 18 megohms, which can remove dust and impurities from the surface to be cleaned.

[0066] The third drying gas removes any residual seventh cleaning solvent from the surface to be cleaned. This third drying gas carries away the residual seventh cleaning solvent and dries the surface, ensuring its dryness. For example, the third drying gas can be nitrogen with a purity of 99.9999% or higher. Nitrogen can purge any remaining ultrapure water, ensuring the dryness of the chassis surface to be cleaned.

[0067] According to some embodiments of the present invention, with reference to Figure 1 The removal of particulate impurities from the surface to be cleaned by the sixth cleaning solvent includes: wiping the surface to be cleaned with a wiping device soaked in the sixth cleaning solvent; for example, the wiping device can be a lint-free cloth with a cleanliness level of 100 or above, and the lint-free cloth can be soaked in solution B to wipe the surface to be cleaned.

[0068] In a specific example, wiping the surface to be cleaned with a wiping tool dipped in the sixth cleaning solvent includes: using multiple wiping tools dipped in the sixth cleaning solvent to wipe the surface to be cleaned; using one wiping tool dipped in the sixth cleaning solvent to wipe the surface to be cleaned; the color of the wiping tool changes; replacing it with a new wiping tool dipped in the sixth cleaning solvent to wipe the surface to be cleaned; until the wiping tool does not change color after wiping the surface to be cleaned, that is, all particulate impurities on the surface to be cleaned have been wiped away.

[0069] The removal of residual sixth cleaning solvent from the surface to be cleaned by the seventh cleaning solvent includes wiping the surface with a wiping device soaked in the seventh cleaning solvent. For example, the seventh cleaning solvent can be ultrapure water with a resistivity of not less than 18 megohms, and the wiping device can be a lint-free cloth with a cleanliness level of 100 or higher. The lint-free cloth can be soaked in the seventh cleaning solvent to wipe the surface to be cleaned.

[0070] In a specific example, wiping the surface to be cleaned with a wiping tool dipped in the seventh cleaning solvent includes: using multiple wiping tools dipped in the seventh cleaning solvent to wipe the surface to be cleaned; using one wiping tool dipped in the seventh cleaning solvent to wipe the surface to be cleaned; the color of the wiping tool changes; replacing it with a new wiping tool dipped in the seventh cleaning solvent to wipe the surface to be cleaned; until the wiping tool does not change color after wiping the surface to be cleaned, that is, all particulate impurities on the surface to be cleaned have been wiped away.

[0071] According to some embodiments of the present invention, with reference to Figure 1 After removing the residual seventh cleaning solvent from the surface to be cleaned by the third drying gas and drying the surface to be cleaned, the process also includes: detecting the surface to be cleaned by ultraviolet light to detect whether there are particulate impurities or fluorescent spots on the surface to be cleaned.

[0072] When there are fluorescent specks of particulate impurities on the surface to be cleaned, the chassis still has particulate impurities on the surface to be cleaned. The chassis is then deeply cleaned to remove the particulate impurities present on the surface to be cleaned.

[0073] When there are no fluorescent dots or particulate impurities on the surface to be cleaned, the particulate impurities on the chassis surface to be cleaned are cleaned, and the chassis cleaning is complete.

[0074] According to some embodiments of the present invention, with reference to Figures 2-4 The sealing structure includes: a sealing cover 10, a sealing ring, an exhaust port plug 21, an electrode protection cover 22, and a nozzle protection cover 23.

[0075] The sealing cover 10 has a cavity 18 with an opening 17 at one end. The chassis is located at the opening 17 to form a closed space between the sealing cover 10 and the chassis. That is, the cavity 18 of the sealing cover 10 is constructed as a closed space. A fixing bracket 13 is provided on the outer peripheral wall of the sealing cover 10. The fixing bracket 13 is used to fix the sealing cover 10 to the chassis, preventing the sealing cover 10 from shaking on the chassis and causing poor sealing.

[0076] The outer peripheral wall of the sealing cover 10 has an inlet 11 and an outlet 12, which communicate with the enclosed space. During the chassis corrosion and passivation stage, the cleaning solvent and drying gas can only enter the enclosed space through the inlet 11, and both the cleaning solvent and drying gas within the enclosed space can be discharged through the outlet 12. Valves are provided on both the inlet 11 and the outlet 12. Closing or opening the valves controls the flow rate into and out of the enclosed space, and also controls the flow rate of the cleaning solvent within the enclosed space.

[0077] The sealing ring is located between the sealing cover 10 and the chassis to seal the assembly gap between the sealing cover 10 and the chassis, thereby further improving the sealing performance between the sealing cover 10 and the chassis and further preventing the cleaning solvent and drying gas in the enclosed space from leaking out from the assembly gap.

[0078] One end of the exhaust port plug 21 is located inside the exhaust port of the chassis to seal the exhaust port. The sealing cover 10 is provided with multiple first fixing members 14, and the other end of the exhaust port plug 21 is fixedly connected to one of the first fixing members 14. When the first fixing member 14 is fixedly connected to the exhaust port plug 21, it provides a fixing force to press the exhaust port plug 21 firmly, preventing it from falling out of the exhaust port. Using the exhaust port plug 21 to seal the exhaust port prevents cleaning solvents during the chassis corrosion passivation stage from entering the exhaust port and corroding it.

[0079] During the initial and deep cleaning stages of the chassis, the exhaust vents can be cleaned.

[0080] For example, one end of the exhaust port plug 21 is located inside the exhaust port, and a stepped surface is formed on the exhaust port plug 21, which abuts against the axial sidewall of the exhaust port. A first gasket can be provided between the stepped surface and the axial sidewall of the exhaust port to further seal the gap between the exhaust port plug 21 and the axial sidewall of the exhaust port. The first fixing member 14 is located on the bottom wall of the sealing cover 10 facing the cavity 18. The first fixing member 14 can be a fixing ring protruding on the bottom wall, with a first internal thread inside the fixing ring. The end of the exhaust port plug 21 away from the stepped surface has a first external thread 211 that mates with the first internal thread, so that the exhaust port plug 21 and the first fixing member 14 are threadedly engaged to press the stepped surface of the exhaust port plug 21 and the first gasket between the stepped surface and the axial sidewall of the exhaust port.

[0081] One end of the electrode protective cover 22 is fitted over the outer periphery of the electrode on the chassis to protect it. The sealing cover 10 has multiple second fixing members 15, and the other end of the electrode protective cover 22 is fixedly connected to one of these second fixing members 15. When the second fixing member 15 is fixedly connected to the electrode protective cover 22, it provides a fixing force to press the electrode protective cover 22 firmly, preventing it from detaching from the electrode. The electrode protective cover 22 protects the electrode from corrosion by the cleaning solvent during the chassis corrosion passivation stage.

[0082] The electrodes of the chassis can be cleaned during the initial cleaning stage and the deep cleaning stage.

[0083] For example, one end of the electrode protective cover 22 has a first protective cover 222, which covers the outer periphery of the electrode on the chassis. A second gasket is provided at the bottom of the first protective cover 222 to further seal the gap between the electrode protective cover 22 and the electrode. The second fixing member 15 is located on the bottom wall of the sealing cover 10 facing the cavity 18. The second fixing member 15 can be a fixing ring protruding on the bottom wall. The end of the electrode protective cover 22 away from the first protective cover 222 is located inside the fixing ring. The fixing ring has a second internal thread, and the other end of the electrode protective cover 22 has a second external thread 221 that mates with the second internal thread to thread the electrode protective cover 22 and the second fixing member 15 together, so that the second fixing member 15 can press the electrode protective cover 22 and the second gasket together.

[0084] One end of the nozzle protective cover 23 is fitted over the outer periphery of the nozzle on the chassis to protect it. The sealing cover 10 has multiple third fixing members 16, and the other end of the nozzle protective cover 23 is fixedly connected to one of these third fixing members 16. When the third fixing member 16 is fixedly connected to the nozzle protective cover 23, it provides a fixing force to press the nozzle protective cover 23 firmly, preventing it from detaching from the nozzle. An electrode protective cover 22 is used to protect the electrode, preventing the cleaning solvent during the chassis corrosion passivation stage from corroding the nozzle on the chassis.

[0085] The nozzles on the chassis can be cleaned during both the initial and deep cleaning stages.

[0086] For example, one end of the nozzle protective cover 23 has a second protective cover 232, which covers the outer periphery of the nozzle on the chassis. A third gasket is provided at the bottom of the second protective cover 232 to further seal the gap between the nozzle protective cover 23 and the nozzle. The third fixing member 16 is located on the bottom wall of the sealing cover 10 facing the cavity 18. The third fixing member 16 can be a fixing ring protruding on the bottom wall. The end of the electrode protective cover 22 away from the second protective cover 232 is located inside the fixing ring. The fixing ring has a third internal thread, and the other end of the nozzle protective cover 23 has a third external thread 231 that mates with the third internal thread to thread the nozzle protective cover 23 and the third fixing member 16 together, so that the third fixing member 16 can press the nozzle protective cover 23 and the third gasket together.

[0087] In one example, the electrode and nozzle have different diameters, with the nozzle diameter being larger than the electrode diameter; combined Figures 2-5As shown, the second protective cover 232 of the nozzle protective cover 23 is installed on the outer periphery of the nozzle of the chassis, and the first protective cover 222 of the electrode protective cover 22 is installed on the outer periphery of the electrode of the chassis. Since the diameter of the nozzle is larger than the diameter of the electrode, the inner diameter d2 of the second protective cover 232 is larger than the inner diameter d1 of the first protective cover 222. The outer diameter of the first protective cover 222 is the diameter d4 of the nozzle protective cover 23, and the outer diameter of the second protective cover 232 is the diameter d3 of the electrode protective cover 22. The diameter of the nozzle protective cover 23 is larger than the diameter of the electrode protective cover 22. One end of the nozzle protective cover 23 is located inside the fixing ring of the third fixing member 16, and one end of the electrode protective cover 22 is located inside the fixing ring of the second fixing member 15. The inner diameter of the fixing ring of the third fixing member 16 is larger than the inner diameter of the fixing ring of the second fixing member 15, that is, the diameter of the third fixing member 16 is larger than the diameter of the second fixing member 15.

[0088] Optionally, the second, third, fourth, fifth, and seventh cleaning solvents in the above examples are all used to clean the surface of the chassis to be cleaned, so as to avoid the residue of impurities, or the residue of other cleaning solvents that chemically corrode the surface to be cleaned, or the residue of compounds after the chemical reaction of other cleaning solvents that chemically corrode the surface to be cleaned with polycrystalline silicon polymer. Therefore, the second, third, fourth, fifth, and seventh cleaning solvents can all be ultrapure water. However, in the scheme of this application, the second, third, fourth, fifth, and seventh cleaning solvents are not limited to ultrapure water. They can also be other aqueous solutions, such as deionized water, distilled water, etc. They can also be hydrochloric acid solutions with a concentration of 1% to 2%, ammonium hydroxide, hydrogen peroxide APM and HPM solutions, and diluted hydrocyanic acid aqueous solutions, etc. This application does not impose any restrictions, as long as the above-mentioned residues on the chassis can be cleaned and the environment inside the electronic-grade polycrystalline silicon reduction furnace is not affected.

[0089] In the above examples, the first, second, and third drying gases are all used to dry the cleaning solvent remaining on the surface to be cleaned on the chassis. Therefore, the second, third, fourth, fifth, and seventh cleaning solvents can all be nitrogen with a purity of not less than 99.9999%. However, in the scheme of this application, the first, second, and third drying gases are not limited to nitrogen, but can also be other gases, such as helium. This application does not impose any restrictions, as long as they can dry the aforementioned residual cleaning solvent on the chassis and do not affect the environment inside the electronic-grade polysilicon reduction furnace.

[0090] In the description of this specification, references to terms such as "some embodiments," "optionally," "furthermore," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0091] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method of cleaning the bottom tray of an electronic grade polysilicon reduction furnace, characterized by, The method comprises: a preliminary cleaning of the base, which comprises removing dust impurities from the surface to be cleaned of the base; a base corrosion passivation, which comprises: forming a closed space with the base by means of a sealing structure, so that the surface to be cleaned is located in the closed space; cleaning the polysilicon polymer on the surface to be cleaned in the closed space, which comprises: introducing a first cleaning solvent into the closed space so that the first cleaning solvent corrodes the polysilicon polymer on the surface to be cleaned for a first predetermined time, the first cleaning solvent comprising an ammonium hydrogen fluoride solution; introducing a second cleaning solvent into the closed space so that the second cleaning solvent cleans the surface to be cleaned for a second predetermined time to remove the corroded polysilicon polymer and the residual first cleaning solvent on the surface to be cleaned; introducing a first drying gas into the closed space to remove the residual second cleaning solvent on the surface to be cleaned and dry the surface to be cleaned; a deep cleaning of the base, which comprises removing the sealing structure and cleaning the surface to be cleaned; the sealing structure comprises: a sealing cover having a cavity with an open end, the base being located at the opening to form the closed space between the sealing cover and the base, a fixing support, an inlet and an outlet being provided on the peripheral wall of the sealing cover, the fixing support being used to fix the sealing cover, and the inlet and the outlet each being provided with a valve; a sealing ring located between the sealing cover and the base to seal the assembly gap between the sealing cover and the base; an exhaust hole plug, one end of which is located in the exhaust hole of the base to seal the exhaust hole, the other end of the exhaust hole plug being fixedly connected with a first fixing member provided on the sealing cover; an electrode protection cover, one end of which is covered on the peripheral side of the electrode of the base, the other end of the electrode protection cover being fixedly connected with a second fixing member provided on the sealing cover; a nozzle protection cover, one end of which is covered on the peripheral side of the nozzle of the base, the other end of the nozzle protection cover being fixedly connected with a third fixing member provided on the sealing cover.

2. The method of claim 1, wherein the cleaning is performed by a robot. After the first drying gas is introduced into the closed space, an acidic solvent is also introduced into the closed space to form a protective film on the cleaned surface to be cleaned; the acidic solvent is introduced into the closed space to form the protective film on the cleaned surface to be cleaned, which comprises: allowing the acidic solvent to contact the base for a third predetermined time to form the protective film on the cleaned surface to be cleaned; an alkaline solvent is introduced into the closed space, and the alkaline solvent reacts with the acidic solvent within a fourth predetermined time to neutralize the acidic solvent; A third cleaning solvent is introduced into the closed space and allowed to clean the surface of the protective film for a fifth predetermined time to remove the acidic solvent and the basic solvent remaining in the closed space.

3. The method of claim 2, wherein the cleaning is performed by a robot. The third cleaning solvent is allowed to clean the surface of the protective film for a fifth predetermined time, and then further comprising: PH value of the third cleaning solvent at the liquid outlet of the closed space is detected by using a PH test paper; When the PH value does not meet the predetermined PH value, the injection of the third cleaning solvent into the closed space is continued; When the PH value meets the predetermined PH value, the cleaning of the third cleaning solvent is ended.

4. The method of claim 3, wherein the cleaning is performed by a robot. The PH value of the third cleaning solvent at the liquid outlet of the closed space is detected by using a PH test paper, and then further comprising: A second drying gas is introduced into the closed space to remove the third cleaning solvent remaining on the surface to be cleaned and to dry the surface to be cleaned.

5. The method of claim 1, wherein the cleaning is performed by a robot. The dust impurities on the surface to be cleaned of the cleaning tray include: The dust impurities on the surface to be cleaned are sucked by using a dust collection method; The dust impurities remaining on the surface to be cleaned are removed by using a fourth cleaning solvent.

6. The method of claim 5, wherein the cleaning is performed by a robot. The dust impurities remaining on the surface to be cleaned are removed by using the fourth cleaning solvent, which includes wiping the surface to be cleaned by using a wiping member dipped in the fourth cleaning solvent.

7. The method of claim 1, wherein the cleaning is performed by a robot. The cleaning of the polysilicon polymer on the surface to be cleaned in the closed space further includes: A fifth cleaning solvent is introduced into the closed space and allowed to clean the surface to be cleaned for a sixth predetermined time.

8. The method of claim 1, wherein the cleaning is performed by a robot. The cleaning of the surface to be cleaned includes: The particle impurities on the surface to be cleaned are removed by using a sixth cleaning solvent; The sixth cleaning solvent remaining on the surface to be cleaned is removed by using a seventh cleaning solvent; The seventh cleaning solvent remaining on the surface to be cleaned is removed by using a third drying gas, and the surface to be cleaned is dried.

9. The cleaning method of the bottom tray of the electronic-grade polysilicon reduction furnace according to claim 8, wherein The particle impurities on the surface to be cleaned are removed by using the sixth cleaning solvent, which includes wiping the surface to be cleaned by using a wiping member dipped in the sixth cleaning solvent; The sixth cleaning solvent remaining on the surface to be cleaned is removed by using the seventh cleaning solvent, which includes wiping the surface to be cleaned by using the wiping member dipped in the seventh cleaning solvent.

10. The method of claim 8, wherein the cleaning is performed by a robot. After the seventh cleaning solvent remaining on the surface to be cleaned is removed by using the third drying gas and the surface to be cleaned is dried, further comprising: The surface to be cleaned is detected by using a purple light lamp to detect whether there are particle impurity fluorescent points on the surface to be cleaned; When there are no particle impurity fluorescent points on the surface to be cleaned, the cleaning of the bottom tray is ended; When there are particle impurity fluorescent points on the surface to be cleaned, the cleaning of the bottom tray is recycled.

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