Process method for refining high-purity silicon

Abstract

The invention discloses a process method for refining high-purity silicon. According to the invention, the electrodeionization system can remove ions in water, including weak electrolyte and trace ions which are difficult to remove through traditional ion exchange resin. Therefore, the purity of water is remarkably improved, and the requirement of ultrapure water is met. The electrodeionization system can provide very stable water quality, and the resin in the electrodeionization module can be continuously regenerated, which means that the fluctuation of the water quality is small, so that the electrodeionization system is very suitable for applications needing continuous supply of high-purity water. Compared with the traditional ion exchange technology, the electrodeionization does not need chemical reagents such as acid and alkali to regenerate the resin, so that the operation cost is reduced, the influence on the environment is reduced, and the whole preparation method is more environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrapure water production, and specifically relates to a process for refining high-purity silicon. Background Art

[0002] Refining high-purity silicon is a key process in the semiconductor and photovoltaic industries. It involves converting natural silicon (Si) into a form of extremely high purity for use in the manufacture of semiconductor devices, solar cells, and other high-tech products. The process of refining high-purity silicon requires precise control and high-tech equipment to ensure the purity and quality of the final product. The purity of high-purity silicon is usually above 99.9999% (6N), and for some specific semiconductor applications, it is even required to reach 99.9999999% (9N) purity. The ultrapure water used to refine high-purity silicon is a type of electronic grade water, which must meet extremely high purity standards. Ultrapure water is an indispensable raw material in semiconductor manufacturing, integrated circuit production, photovoltaic industry, and other high-tech industries. In the process of refining high-purity silicon, the quality of ultrapure water directly affects the performance and reliability of the final product.

[0003] However, in the common ultrapure water production method, the efficiency of removing residual ions in water is relatively low, which makes the entire ultrapure water production process consume a lot of time. At the same time, traditional ion exchange technology requires the use of chemical reagents such as acids and alkalis to regenerate the resin, which increases the burden on the environment. Summary of the invention

[0004] The purpose of the present invention is to provide a process for refining high-purity silicon in order to solve the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: a process for refining high-purity silicon, the production method comprising the following steps:

[0006] S1: After selecting a suitable water source, pre-treatment and mechanical filtration are carried out: suspended matter, particulate matter and organic matter in the water are removed through filters of different precisions including quartz sand layer and activated carbon layer;

[0007] S2: Perform ion exchange: Use ion exchange resin to remove hardness ions (such as calcium and magnesium ions) and some heavy metal ions in water;

[0008] S3: Primary purification, removing most ions, organic matter and microorganisms in water through a semi-permeable membrane under high pressure. Reverse osmosis can remove about 98% of dissolved solids in water;

[0009] S4: using a mixed bed ion exchange resin to further remove ions from the water, wherein the mixed bed ion exchange resin is a monolithic organic porous anion exchanger comprising a continuous skeleton phase and a continuous pore phase, the thickness of the continuous skeleton is 1 to 100 μm, the average diameter of the continuous pores is 1 to 1000 μm, the total pore volume is 0.5 to 50 mL / g, the anion exchange capacity in a wet state is 0.1 to 1.0 mg equivalent / mL, and the anion exchange groups are uniformly distributed in the organic porous anion exchanger.

[0010] S5: Perform ultrafiltration deep treatment: Use ultrafiltration membrane to further remove tiny particles, macromolecular organic matter and certain viruses in the water;

[0011] S6: Perform nanofiltration (NF) to remove certain specific organic matter and divalent ions through nanofiltration membranes. The pore size of nanofiltration is between reverse osmosis and ultrafiltration, and it can remove substances with a relative molecular mass of more than several hundred;

[0012] S7: Perform electrodeionization treatment: Remove the remaining ions in the water through the combined action of electrolysis and ion exchange. Electrodeionization achieves the production of high-purity water at a lower pressure. A photocatalytic oxidation reactor is integrated before the electrodeionization unit, using ultraviolet light and catalysts (such as titanium dioxide) to decompose organic matter in the water. PCO can break the chemical bonds of organic matter and convert it into harmless carbon dioxide and water;

[0013] S8: Perform terminal treatment: destroy the DNA of microorganisms in the water through ultraviolet irradiation to achieve the purpose of disinfection. Ultraviolet disinfection can effectively inactivate bacteria, viruses and other microorganisms in water;

[0014] S9: Pure water is introduced into the Q-Gard pretreatment purification column of the Milli-QAdvantage A10 water production unit for pretreatment; then, the pretreated pure water is purified by the built-in Quantum refining purification column to remove trace levels of ions and organic pollutants to meet the experimental water quality requirements: Finally, the treated ultrapure water is circulated to the Q-POD water intake unit through a low-elution pipeline, and the TOC monitor and high-sensitivity resistivity meter are used to measure the TOC and resistivity levels in the water. Once qualified, the entire ultrapure water production process for refining high-purity silicon can be completed.

[0015] In a preferred embodiment, in step S1, the water source is selected from tap water, groundwater or river water.

[0016] In a preferred embodiment, in step S3, sufficient pretreatment must be performed before the reverse osmosis system, including mechanical filtration, softening, flocculation and sedimentation steps to remove suspended matter, particulate matter, hardness ions and organic matter.

[0017] In a preferred embodiment, in step S4, the mixed bed ion exchange resin is filled into the exchange column. Before filling, it is necessary to ensure that the resin is fully wetted and cleaned. b. Resin activation: The resin is activated using an appropriate acid or alkali solution to remove impurities and residual ions in the resin.

[0018] In a preferred embodiment, in step S4, the ion exchange process is as follows: a. Influent water passes through the resin layer: Influent water enters from the bottom of the exchange column and flows upward through the resin layer.

[0019] b. Ion removal: The cations and anions in the resin are exchanged with the ions in the water, thereby removing the ions in the water. c. Effluent collection: The treated water flows out from the top of the exchange column and is collected in the effluent system.

[0020] In a preferred embodiment, in step S5, the pore size of the ultrafiltration membrane is between 0.01 and 1 micron, which can effectively remove many impurities that cannot be removed by reverse osmosis membranes.

[0021] In a preferred embodiment, in step S6, the nanofiltration process: a. Water inlet: the pretreated water is fed into the nanofiltration membrane assembly by a high-pressure pump. b. Membrane separation: water passes through the nanofiltration membrane under pressure, and water molecules and partially dissolved inorganic salts (such as divalent ions) pass through the membrane, while macromolecular organic matter, suspended matter and most monovalent ions are retained by the membrane. c. Product water collection: the clean water (product water) that passes through the membrane is collected and used in subsequent processes or directly used. d. Brine discharge: the substances retained by the membrane are discharged with the brine, and the brine can be further treated or discharged.

[0022] In a preferred embodiment, in step S7, electrochemical oxidation (ECO) treatment is performed: an electrochemical oxidation step is added before the electrodeionization unit, and strong oxidants (such as hydroxyl radicals) generated by electrolysis are used to oxidize organic matter and microorganisms in the water. High-energy electrons and free radicals generated by plasma are used to oxidize organic matter and microorganisms in the water. Plasma oxidation can be carried out at normal temperature and pressure, and can treat various types of pollutants.

[0023] In a preferred embodiment, in step S9, the ultrapure water is placed in a closed circulation system to maintain water quality through continuous circulation. The circulation system can prevent water from being stagnant for a long time, which may lead to bacterial growth or precipitation of impurities.

[0024] In a preferred embodiment, in step S9, high-quality materials (such as stainless steel, polytetrafluoroethylene, etc.) are used to construct the distribution system to ensure that the water is not contaminated during the distribution process. The design of the distribution system should reduce dead water areas and use dead-angle-free connections as much as possible.

[0025] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0026] 1. In the present invention, the electrodeionization system is able to remove ions from water, including weak electrolytes and trace amounts of ions that are difficult to remove with conventional ion exchange resins. This significantly improves the purity of water and meets the requirements for ultrapure water. The electrodeionization system is able to provide very stable water quality because the resin in the electrodeionization module is constantly regenerated, which means that the water quality fluctuates less, making it very suitable for applications that require a continuous supply of high-purity water. Reduced use of chemical additives: Compared with conventional ion exchange technology, electrodeionization does not require the use of chemical reagents such as acids and alkalis to regenerate the resin, which not only reduces operating costs, but also reduces the impact on the environment, thereby making the entire preparation method more environmentally friendly.

[0027] 2. In the present invention, the mixed bed ion exchange resin is a monolithic organic porous anion exchanger comprising a continuous skeleton phase and a continuous pore phase, a continuous skeleton having a thickness of 1 to 100 μm, an average diameter of continuous pores of 1 to 1000 μm, a total pore volume of 0.5 to 50 mL / g, an anion exchange capacity of 0.1 to 1.0 mg equivalent / mL in a wet state, and an anion exchange group uniformly distributed in the organic porous anion exchanger. The design of this monolithic organic porous anion exchanger makes it very efficient in the preparation of ultrapure water. It can quickly and effectively remove ions from water, and at the same time, due to the uniform distribution of anion exchange groups, it can ensure long-term efficient operation. In addition, the structure of this resin also helps to reduce pressure drop, reduce energy consumption, and extend the service life of the resin. In practical applications, mixed bed ion exchange resins are usually used after the reverse osmosis (RO) system and before the EDI system as an intermediate step in the preparation of ultrapure water to ensure that the ion content in the water reaches an extremely low level. Thereby further improving the anion exchange efficiency and increasing the efficiency of the overall ultrapure water preparation process. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Example:

[0030] A process for refining high-purity silicon, the manufacturing method comprises the following steps:

[0031] S1: After selecting a suitable water source, pre-treatment and mechanical filtration are carried out: suspended matter, particulate matter and organic matter in the water are removed through filters of different precisions including quartz sand layer and activated carbon layer;

[0032] S2: Perform ion exchange: Use ion exchange resin to remove hardness ions (such as calcium and magnesium ions) and some heavy metal ions in water;

[0033] S3: Primary purification, removing most ions, organic matter and microorganisms in water through a semi-permeable membrane under high pressure. Reverse osmosis can remove about 98% of dissolved solids in water;

[0034] S4: using a mixed bed ion exchange resin to further remove ions from the water, wherein the mixed bed ion exchange resin is a monolithic organic porous anion exchanger comprising a continuous skeleton phase and a continuous pore phase, the thickness of the continuous skeleton is 1 to 100 μm, the average diameter of the continuous pores is 1 to 1000 μm, the total pore volume is 0.5 to 50 mL / g, the anion exchange capacity in a wet state is 0.1 to 1.0 mg equivalent / mL, and the anion exchange groups are uniformly distributed in the organic porous anion exchanger.

[0035] S5: Perform ultrafiltration deep treatment: Use ultrafiltration membrane to further remove tiny particles, macromolecular organic matter and certain viruses in the water;

[0036] S6: Perform nanofiltration (NF) to remove certain specific organic matter and divalent ions through nanofiltration membranes. The pore size of nanofiltration is between reverse osmosis and ultrafiltration, and it can remove substances with a relative molecular mass of more than several hundred;

[0037] S7: Perform electrodeionization treatment: Remove the remaining ions in the water through the combined action of electrolysis and ion exchange. Electrodeionization achieves the production of high-purity water at a lower pressure. A photocatalytic oxidation reactor is integrated before the electrodeionization unit, using ultraviolet light and catalysts (such as titanium dioxide) to decompose organic matter in the water. PCO can break the chemical bonds of organic matter and convert it into harmless carbon dioxide and water;

[0038] S8: Perform terminal treatment: destroy the DNA of microorganisms in the water through ultraviolet irradiation to achieve the purpose of disinfection. Ultraviolet disinfection can effectively inactivate bacteria, viruses and other microorganisms in water;

[0039] S9: Pure water is introduced into the Q-Gard pretreatment purification column of the Milli-QAdvantage A10 water production unit for pretreatment; then, the pretreated pure water is purified by the built-in Quantum refining purification column to remove trace levels of ions and organic pollutants to meet the experimental water quality requirements: Finally, the treated ultrapure water is circulated to the Q-POD water intake unit through a low-elution pipeline, and the TOC monitor and high-sensitivity resistivity meter are used to measure the TOC and resistivity levels in the water. Once qualified, the entire ultrapure water production process for refining high-purity silicon can be completed.

[0040] In step S1, the water source is selected from tap water, groundwater or river water.

[0041] In step S3, sufficient pretreatment must be performed before the reverse osmosis system, including mechanical filtration, softening, flocculation and sedimentation steps to remove suspended matter, particulate matter, hardness ions and organic matter.

[0042] In step S4, the mixed bed ion exchange resin is filled into the exchange column. Before filling, the resin must be fully moistened and cleaned. b. Resin activation: The resin is activated using an appropriate acid or alkali solution to remove impurities and residual ions in the resin.

[0043] In step S4, the ion exchange process is as follows: a. Influent water passes through the resin layer: Influent water enters from the bottom of the exchange column and flows upward through the resin layer. b. Ion removal: The cations and anions in the resin are exchanged with the ions in the water, thereby removing the ions in the water. c. Effluent collection: The treated water flows out from the top of the exchange column and is collected in the effluent system.

[0044] In step S5, the pore size of the ultrafiltration membrane is between 0.01 and 1 micron, which can effectively remove many impurities that cannot be removed by reverse osmosis membranes.

[0045] In step S6, the nanofiltration process: a. Water inlet: The pretreated water is fed into the nanofiltration membrane assembly by a high-pressure pump. b. Membrane separation: Water passes through the nanofiltration membrane under pressure, and water molecules and partially dissolved inorganic salts (such as divalent ions) pass through the membrane, while large molecular organic matter, suspended matter and most monovalent ions are retained by the membrane. c. Product water collection: The clean water (product water) that passes through the membrane is collected and used in subsequent processes or directly used. d. Brine discharge: The substances retained by the membrane are discharged with the brine, and the brine can be further treated or discharged.

[0046] In step S7, electrochemical oxidation (ECO) treatment is performed: an electrochemical oxidation step is added before the electrodeionization unit, and strong oxidants (such as hydroxyl radicals) generated by electrolysis are used to oxidize organic matter and microorganisms in the water. High-energy electrons and free radicals generated by plasma are used to oxidize organic matter and microorganisms in the water. Plasma oxidation can be carried out at normal temperature and pressure, and can treat a variety of types of pollutants.

[0047] In step S9, the ultrapure water is placed in a closed circulation system to maintain water quality through continuous circulation. The circulation system can prevent water from being static for a long time, which may lead to bacterial growth or precipitation of impurities.

[0048] In step S9, high-quality materials (such as stainless steel, polytetrafluoroethylene, etc.) are used to construct the distribution system to ensure that the water is not contaminated during the distribution process. The design of the distribution system should reduce dead water areas and use dead-angle-free connections as much as possible.

[0049] In the present invention, the electrodeionization system is able to remove ions from water, including weak electrolytes and trace amounts of ions that are difficult to remove with conventional ion exchange resins. This significantly improves the purity of the water and meets the requirements for ultrapure water. The electrodeionization system is able to provide very stable water quality because the resin in the electrodeionization module is constantly regenerated, which means that the water quality fluctuates less, making it very suitable for applications that require a continuous supply of high-purity water. Reduced use of chemical additives: Compared with conventional ion exchange technology, electrodeionization does not require the use of chemical reagents such as acids and alkalis to regenerate the resin, which not only reduces operating costs, but also reduces the impact on the environment, thereby making the entire preparation method more environmentally friendly.

[0050] In the present invention, the mixed bed ion exchange resin is a monolithic organic porous anion exchanger comprising a continuous skeleton phase and a continuous pore phase, a continuous skeleton having a thickness of 1 to 100 μm, an average diameter of continuous pores of 1 to 1000 μm, a total pore volume of 0.5 to 50 mL / g, an anion exchange capacity of 0.1 to 1.0 mg equivalent / mL in a wet state, and an anion exchange group uniformly distributed in the organic porous anion exchanger. The design of this monolithic organic porous anion exchanger makes it very efficient in the preparation of ultrapure water. It can quickly and effectively remove ions in water, and at the same time, due to the uniform distribution of anion exchange groups, long-term efficient operation can be guaranteed. In addition, the structure of this resin also helps to reduce pressure drop, reduce energy consumption, and extend the service life of the resin. In practical applications, mixed bed ion exchange resins are usually used after reverse osmosis (RO) systems and before EDI systems as an intermediate step in the preparation of ultrapure water to ensure that the ion content in water reaches an extremely low level. Thereby further improving the anion exchange efficiency and increasing the efficiency of the overall ultrapure water preparation process.

[0051] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for refining high-purity silicon, characterized in that: The production method comprises the following steps: S1: After selecting a suitable water source, pre-treatment and mechanical filtration are carried out: suspended matter, particulate matter and organic matter in the water are removed through filters of different precisions including quartz sand layer and activated carbon layer; S2: Perform ion exchange: Use ion exchange resin to remove hardness ions and some heavy metal ions in water; S3: Primary purification, removing most ions, organic matter and microorganisms in water through a semipermeable membrane under high pressure; reverse osmosis can remove about 98% of dissolved solids in water; S4: using a mixed bed ion exchange resin to further remove ions from the water, wherein the mixed bed ion exchange resin is a monolithic organic porous anion exchanger comprising a continuous skeleton phase and a continuous pore phase, the thickness of the continuous skeleton is 1 to 100 μm, the average diameter of the continuous pores is 1 to 1000 μm, the total pore volume is 0.5 to 50 mL / g, the anion exchange capacity in a wet state is 0.1 to 1.0 mg equivalent / mL, and the anion exchange groups are uniformly distributed in the organic porous anion exchanger. S5: Perform ultrafiltration deep treatment: Use ultrafiltration membrane to further remove tiny particles, macromolecular organic matter and certain viruses in the water; S6: Perform nanofiltration to remove certain specific organic matter and divalent ions through a nanofiltration membrane; the pore size of nanofiltration is between reverse osmosis and ultrafiltration, and it can remove substances with a relative molecular mass of more than several hundred; S7: Perform electrodeionization treatment: Remove the remaining ions in the water through the combined action of electrolysis and ion exchange; electrodeionization achieves the production of high-purity water at a lower pressure, and a photocatalytic oxidation reactor is integrated before the electrodeionization unit to decompose organic matter in the water using ultraviolet light and catalysts; PCO can break the chemical bonds of organic matter and convert it into harmless carbon dioxide and water; S8: Perform terminal treatment: destroy the DNA of microorganisms in the water through ultraviolet irradiation to achieve the purpose of disinfection; ultraviolet disinfection can effectively inactivate bacteria, viruses and other microorganisms in the water; S9: Pure water is introduced into the Q-Gard pretreatment purification column of the Milli-Q Advantage A10 water production unit for pretreatment; then, the pretreated pure water is purified by the built-in Quantum refining purification column to remove trace levels of ions and organic pollutants to meet the experimental water quality requirements: Finally, the treated ultrapure water is circulated to the Q-POD water intake unit through a low-dissolution pipeline, and the TOC monitor and high-sensitivity resistivity meter are used to measure the TOC and resistivity levels in the water. Once qualified, the entire ultrapure water production process for refining high-purity silicon can be completed.

2. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S1, the water source is selected from tap water, groundwater or river water.

3. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S3, sufficient pretreatment must be performed before the reverse osmosis system, including mechanical filtration, softening, flocculation and sedimentation steps to remove suspended matter, particulate matter, hardness ions and organic matter.

4. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In the step S4, the mixed bed ion exchange resin is filled into the exchange column; before filling, it is necessary to ensure that the resin has been fully moistened and cleaned; b. Resin activation: The resin is activated using an appropriate acid or alkali solution to remove impurities and residual ions in the resin.

5. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S4, the ion exchange process is as follows: a. Influent water passes through the resin layer: Influent water enters from the bottom of the exchange column and flows upward through the resin layer; b. Ion removal: The cations and anions in the resin are exchanged with the ions in the water, thereby removing the ions in the water; c. Effluent collection: The treated water flows out from the top of the exchange column and is collected in the effluent system.

6. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S5, the pore size of the ultrafiltration membrane is between 0.01 and 1 micron, which can effectively remove many impurities that cannot be removed by reverse osmosis membranes.

7. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S6, the nanofiltration process is as follows: a. water inlet: the pretreated water is fed into the nanofiltration membrane assembly by a high-pressure pump; b. membrane separation: water passes through the nanofiltration membrane under pressure, water molecules and partially dissolved inorganic salts pass through the membrane, while macromolecular organic matter, suspended matter and most monovalent ions are retained by the membrane; c. Product water collection: Clean water passing through the membrane is collected and used in subsequent processes or directly used; d. Brine discharge: Substances retained by the membrane are discharged with the brine, which can be further processed or discharged.

8. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S7, electrochemical oxidation treatment is performed: an electrochemical oxidation step is added before the electrodeionization unit, and the strong oxidant generated by electrolysis is used to oxidize the organic matter and microorganisms in the water; the high-energy electrons and free radicals generated by plasma are used to oxidize the organic matter and microorganisms in the water; plasma oxidation can be carried out at normal temperature and pressure, and can treat various types of pollutants.

9. A process for refining high-purity silicon as claimed in claim 1, characterized in that: In step S9, the ultrapure water is placed in a closed circulation system to maintain water quality through continuous circulation; the circulation system can prevent water from being stagnant for a long time, which may cause bacterial growth or precipitation of impurities.

10. A process for refining high-purity silicon according to claim 1, characterized in that: In step S9, high-quality materials are used to construct the distribution system to ensure that the water is not contaminated during the distribution process; the design of the distribution system should reduce dead water areas and use dead-angle-free connections as much as possible.