A single crystal silicon wafer cleaning system and method

Abstract

The application provides a single crystal silicon wafer cleaning system and method, and the cleaning system comprises a first cleaning tank, a second cleaning tank, a third cleaning tank, a fourth cleaning tank and a high-pressure conveying device; the fourth cleaning tank comprises a first tank body for containing a first cleaning solution containing hydrogen peroxide aqueous solution, a second tank body for containing a second cleaning solution containing hydrogen peroxide aqueous solution, a third tank body for containing a third cleaning solution containing hydrogen peroxide aqueous solution, at least one first light source for providing light to the first tank body, and at least one second light source for providing light to the third tank body; the first tank body and the second tank body are communicated through a first anti-radical oxidation reverse osmosis membrane; the second tank body and the third tank body are communicated through a second anti-radical oxidation reverse osmosis membrane; at least one composite plate is arranged in the first tank body and the second tank body respectively; each composite plate comprises doped graphene, and the problems of high single crystal silicon wafer cleaning cost and complex wastewater treatment are solved.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer cleaning, and more specifically, to a single-crystal silicon wafer cleaning system and method. Background Technology

[0002] Silicon wafers are a core material in the fabrication of solar cells, and their surface condition and the degree of contaminant removal directly affect the yield and power generation efficiency of the finished solar cells. The main sources of contaminants on silicon wafers include: process flow, reagents, human contact, environment, and water. The main forms of contamination on silicon wafers include: organic residues (including cleaning agent residues, fingerprints, adhesive residues, etc.), metal ion residues, silicon powder contamination, and watermark contamination.

[0003] Existing technologies typically employ cleaning agents containing large amounts of macromolecular organic reagents. However, these reagents are severely depleted during the cleaning process and cannot be reused after being contaminated with silicon powder, increasing the complexity and cost of wastewater treatment. Other existing technologies use alkaline solutions prepared with potassium hydroxide (KOH) or sodium hydroxide (NaOH) and H₂O₂ (hydrogen peroxide) as cleaning solutions, utilizing their strong oxidizing properties to remove contaminants from the silicon wafer surface at a certain temperature. However, this method has limited cleaning capacity, and the poor stability of hydrogen peroxide necessitates continuous replenishment, resulting in extremely high consumption of alkali and hydrogen peroxide, high costs, and difficulty in controlling process stability. Summary of the Invention

[0004] The main objective of this invention is to provide a single-crystal silicon wafer cleaning system and method to solve the problems of high cleaning cost and complex wastewater treatment in the prior art.

[0005] To achieve the above objectives, the present invention provides a single-crystal silicon wafer cleaning system, comprising: The first cleaning tank is used to hold pure water; A second cleaning tank is used to hold a cleaning solution containing an alkaline substance and a surfactant; the alkaline substance includes at least one of sodium hydroxide and potassium hydroxide, and the surfactant includes alkyl glycosides; The third cleaning tank is used to hold pure water; The fourth cleaning tank includes a first tank for holding a first cleaning solution containing a hydrogen peroxide aqueous solution, a second tank for holding a second cleaning solution containing a hydrogen peroxide aqueous solution, a third tank for holding a third cleaning solution containing a hydrogen peroxide aqueous solution, at least one first light source for providing illumination to the first tank, and at least one second light source for providing illumination to the third tank. The first tank and the second tank are connected by a first anti-free radical oxidation reverse osmosis membrane, and the second tank and the third tank are connected by a second anti-free radical oxidation reverse osmosis membrane. At least one composite plate is respectively disposed in the first tank and the second tank. Each composite plate includes doped graphene. A high-pressure conveying device is used to convey a first cleaning solution containing an aqueous hydrogen peroxide solution into a first tank and drive water molecules in the first cleaning solution containing an aqueous hydrogen peroxide solution through a first anti-free radical oxidation reverse osmosis membrane; and to convey a third cleaning solution containing an aqueous hydrogen peroxide solution into a third tank and drive water molecules in the third cleaning solution containing an aqueous hydrogen peroxide solution through a second anti-free radical oxidation reverse osmosis membrane.

[0006] Furthermore, at least one air bubbling device is provided in each of the first, second, and third tanks.

[0007] Furthermore, a first cover plate is provided at the upper end of the first tank and a first liquid filling port is provided on the first cover plate; a second cover plate is provided at the upper end of the third tank and a second liquid filling port is provided on the second cover plate; the high-pressure conveying device includes a first high-pressure pump and a second high-pressure pump, the first liquid filling port is connected to the liquid outlet of the first high-pressure pump, and the second liquid filling port is connected to the liquid outlet of the second high-pressure pump.

[0008] Preferably, each air bubbling device is disposed at the bottom of the first tank, the second tank, and the third tank.

[0009] Furthermore, each of the first light sources and each of the second light sources is independently selected from either an incandescent lamp or a xenon lamp.

[0010] Furthermore, each first light source is disposed on the upper part of the first tank, and each second light source is disposed on the upper part of the third tank.

[0011] Preferably, each composite plate located in the first tank is arranged perpendicular to the bottom of the first tank, and each composite plate located in the third tank is arranged perpendicular to the bottom of the third tank.

[0012] More preferably, each composite plate in the first tank is located below each first light source, and each composite plate in the third tank is located below each second light source.

[0013] Furthermore, the alkyl glycoside is selected from at least one of APG-1214 and dodecyl glucoside.

[0014] Furthermore, the doped graphene includes at least one of nitrogen-doped graphene and phosphorus-doped graphene.

[0015] Furthermore, each composite board also includes a polymer matrix, which includes at least one of polystyrene and polypropylene, with doped graphene distributed on the surface of the polymer matrix.

[0016] Furthermore, the first anti-free radical oxidation reverse osmosis membrane and the second anti-free radical oxidation reverse osmosis membrane are respectively antioxidant polyamide reverse osmosis membranes.

[0017] Furthermore, the monocrystalline silicon wafer cleaning system also includes an automatic turbidity monitoring system, which includes a yellow target, a CCD visual inspection probe and image processing device, a first control device, a drainage device and a water filling device. The yellow marker is placed at the bottom of the first cleaning tank; The CCD visual inspection probe is used to acquire images of the yellow target and send them to the image processing device; The image processing device is used to receive an image of the yellow target and process the image of the yellow target to obtain the brightness value and the sharpness value of the yellow target, and then send them to the first control device. The first control device is used to receive the brightness value and clarity value of the yellow target and, when the brightness value and / or clarity value of the yellow target are lower than a preset value, control the drainage device to drain the first cleaning tank and, after the drainage device has drained the water, control the water filling device to add water to the first cleaning tank.

[0018] Furthermore, the cleaning solution containing alkaline substances and surfactants has a pH value of 11 to 12, and the concentration of alkyl glycosides in the cleaning solution containing alkaline substances and surfactants is 0.1% to 1% by weight.

[0019] Preferably, the monocrystalline silicon wafer cleaning system further includes an automatic pH monitoring system, which includes a pH sensor, a second control device, and an alarm device. A pH sensor is installed in the second cleaning tank to obtain the pH value of the cleaning solution containing alkaline substances and surfactants and send it to the second control device. The second control device is used to receive the pH value of the cleaning solution containing alkaline substances and surfactants, and to control the alarm device to sound an alarm when the pH value exceeds the preset range.

[0020] Furthermore, by weight percentage, the first cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide, the third cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide, and the second cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide.

[0021] Furthermore, the monocrystalline silicon wafer cleaning system also includes an automatic hydrogen peroxide concentration monitoring system, which includes a first online hydrogen peroxide concentration analyzer, a second online hydrogen peroxide concentration analyzer, a third control device, a first hydrogen peroxide feeding device, and a second hydrogen peroxide feeding device. The first hydrogen peroxide online concentration analyzer is installed in the first tank and is used to obtain the concentration of hydrogen peroxide in the first cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device. The second hydrogen peroxide online concentration analyzer is installed in the third tank to obtain the concentration of hydrogen peroxide in the third cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device. The third control device is used to obtain the concentration of hydrogen peroxide in the first cleaning solution containing an aqueous solution of hydrogen peroxide and, when the concentration is lower than a preset value, control the first hydrogen peroxide feeding device to add hydrogen peroxide to the first tank; and to obtain the concentration of hydrogen peroxide in the third cleaning solution containing an aqueous solution of hydrogen peroxide and, when the concentration is lower than a preset value, control the second hydrogen peroxide feeding device to add hydrogen peroxide to the third tank.

[0022] According to another aspect of the present invention, a method for cleaning single-crystal silicon wafers using the above-described single-crystal silicon wafer cleaning system is provided, comprising the following steps: Step S1: Place the monocrystalline silicon wafer in the first cleaning tank for the first cleaning. Step S2: Place the monocrystalline silicon wafer that has undergone the first cleaning into the second cleaning tank for a second cleaning. Step S3: Place the monocrystalline silicon wafer that has undergone the second cleaning into the third cleaning tank for a third cleaning. Step S4: Place the monocrystalline silicon wafer that has undergone the third cleaning into the second tank for the fourth cleaning.

[0023] Furthermore, the first cleaning time is 150s to 200s, the second cleaning time is 150s to 200s, the third cleaning time is 150s to 200s, and the fourth cleaning time is 100s to 250s.

[0024] Furthermore, steps S1, S2, S3, and S4 are all performed at 20°C to 30°C.

[0025] Furthermore, during the fourth cleaning process, air was blown into the first tank, the second tank, and the third tank, respectively. The air flow rates for the first tank, the second tank, and the third tank were 0.5 L / min.

[0026] Using the technical solution of this invention, the monocrystalline silicon wafer is first pre-cleaned by passing it through pure water in the first cleaning tank to remove large particulate impurities and some soluble contaminants. After cleaning in the first cleaning tank, the monocrystalline silicon wafers can then enter the second cleaning tank for a second cleaning. This second cleaning tank contains a cleaning solution containing alkaline substances and surfactants. Because oily impurities are molecular organic impurities, their adsorption force with the surface of the monocrystalline silicon wafer is weak, and they also have hydrophobic characteristics, which mask the removal of ionic impurities. Alkyl glycosides are nonionic surfactants. Utilizing the strong detergency of alkyl glycosides against molecular organic impurities, most of the oily organic matter on the surface of the silicon wafer can be removed. At the same time, the strong alkalinity of sodium hydroxide reacts with some organic matter or decomposes ester oily water to generate substances that are easily soluble in water, thereby effectively removing some molecular organic impurities to facilitate the subsequent removal of ionic impurities. In addition, sodium hydroxide can also effectively remove residual silicon powder on the surface of the monocrystalline silicon wafer or remove residual iron ions, copper ions, and other metal ion impurities on the surface of the monocrystalline silicon wafer through precipitation or complexation reactions. Furthermore, alkyl glycosides are also biodegradable and have virtually no pollution to the environment. After cleaning in the second cleaning tank, the silicon wafer can be rinsed again with pure water in the third cleaning tank to remove residual cleaning reagents and impurities such as sodium silicate on the surface of the monocrystalline silicon wafer, preparing it for the subsequent deep cleaning (deep oxidation of ionic impurities). In the fourth cleaning tank used for deep cleaning, the first, second, and third tanks respectively contain cleaning solutions containing hydrogen peroxide aqueous solution. Under light illumination, the doped graphene on the composite plate in the first tank undergoes a redox reaction with hydrogen peroxide, generating hydroxyl radicals (·OH). Hydroxyl radicals are highly efficient oxidants that can react with ionic impurities on the silicon wafer surface, converting them into soluble substances, thereby achieving deep cleaning. Simultaneously, hydroxyl radicals (·OH) are generated... Hydroxyl radicals (OH) can oxidize heavy metal ions on the surface of monocrystalline silicon wafers into precipitates or more easily processed forms, which are then removed from the wafer surface through a cleaning process. Furthermore, the design of the first and second anti-free radical oxidation reverse osmosis membranes and the high-pressure delivery device ensures that the generated high concentrations of hydroxyl radicals can be transported with water molecules from the first and third tanks to the second tank for deep purification of the silicon wafers. Simultaneously, it prevents substances from the intermediate tanks from flowing back into the first and second tanks, avoiding secondary contamination within the first and third tanks. Therefore, the cleaning solution in the first and third tanks can be reused continuously; only the second tank needs to be replaced when necessary. The cleaning solution within the tank is sufficient, reducing the consumption of sodium hydroxide and hydrogen peroxide and lowering cleaning costs. Furthermore, the design employing a first and a second anti-free radical oxidation reverse osmosis membrane allows for control of the cleaning efficiency of the monocrystalline silicon wafers in the second tank by adjusting the hydrogen peroxide concentration in the first and third tanks, resulting in a highly controllable and stable cleaning process. Finally, in the fourth cleaning tank, the synergistic effect of hydrogen peroxide and the hydroxyl radicals catalyzed by the composite plate with doped graphene significantly improves the cleanliness of the monocrystalline silicon wafer surface. This makes it particularly suitable for silicon wafer cleaning in semiconductor manufacturing and solar panel production, helping to improve product performance and yield.

[0027] The monocrystalline silicon wafer cleaning system of the present invention is simple and easy to operate. The components of each cleaning solution are simple and the waste liquid treatment cost is low. It can effectively clean the surface of monocrystalline silicon wafers while having a low cleaning cost. Attached Figure Description

[0028] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the external three-dimensional structure of the fourth cleaning tank in a single-crystal silicon wafer cleaning system according to an embodiment of the present invention is shown; and Figure 2 A three-dimensional structural diagram of the interior of the fourth cleaning tank in a single-crystal silicon wafer cleaning system according to an embodiment of the present invention is shown, wherein the above figure includes the following reference numerals: 1. Fourth cleaning tank; 11. First tank body; 111. First cover plate; 112. First liquid inlet; 12. Second tank body; 13. Third tank body; 131. Second cover plate; 132. Second liquid inlet; 2. First anti-free radical oxidation reverse osmosis membrane; 3. Second anti-free radical oxidation reverse osmosis membrane; 4. Composite board; 5. Air bubbling device; 6. First light source; 7. Second light source. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0031] As described in the background section, existing technologies suffer from high cleaning costs for monocrystalline silicon wafers and complex wastewater treatment. To address these issues, such as... Figure 1 and Figure 2 As shown, the present invention provides a single-crystal silicon wafer cleaning system, including a first cleaning tank for holding pure water; A second cleaning tank is used to hold a cleaning solution containing an alkaline substance and a surfactant; the alkaline substance includes at least one of sodium hydroxide and potassium hydroxide, and the surfactant includes alkyl glycosides; The third cleaning tank is used to hold pure water; The fourth cleaning tank 1 includes a first tank 11 for holding a first cleaning solution containing a hydrogen peroxide aqueous solution, a second tank 12 for holding a second cleaning solution containing a hydrogen peroxide aqueous solution, a third tank 13 for holding a third cleaning solution containing a hydrogen peroxide aqueous solution, at least one first light source 6 for providing illumination to the first tank 11, and at least one second light source 7 for providing illumination to the third tank 13. The first tank 11 and the second tank 12 are connected by a first anti-free radical oxidation reverse osmosis membrane 2, and the second tank 12 and the third tank 13 are connected by a second anti-free radical oxidation reverse osmosis membrane 3. At least one composite plate 4 is respectively disposed in the first tank 11 and the second tank 12. Each composite plate 4 includes doped graphene. The device includes a high-pressure conveying unit for conveying a first cleaning solution containing an aqueous hydrogen peroxide solution into the first tank 11 and driving water molecules in the first cleaning solution containing an aqueous hydrogen peroxide solution through a first anti-free radical oxidation reverse osmosis membrane, and for conveying a third cleaning solution containing an aqueous hydrogen peroxide solution into the third tank 13 and driving water molecules in the third cleaning solution containing an aqueous hydrogen peroxide solution through a second anti-free radical oxidation reverse osmosis membrane 3.

[0032] To achieve better cleaning results and reduce cleaning costs, this invention provides a monocrystalline silicon wafer cleaning system. The monocrystalline silicon wafer is first pre-cleaned with pure water in a first cleaning tank to remove large particulate impurities and some soluble contaminants. After cleaning in the first cleaning tank, the monocrystalline silicon wafer can then enter the second cleaning tank for a second cleaning. The second cleaning tank contains a cleaning solution containing alkaline substances and surfactants. Because oily impurities are molecular organic impurities, their adsorption force with the surface of the monocrystalline silicon wafer is weak, and they also have hydrophobic characteristics, which mask the removal of ionic impurities. Alkyl glycosides are nonionic surfactants. The strong detergency of alkyl glycosides for molecular organic impurities can remove most of the oily organic matter on the surface of the silicon wafer. At the same time, the strong alkalinity of sodium hydroxide reacts with some organic matter (as shown in Formula I) or decomposes ester oily water to generate substances that are easily soluble in water, thereby effectively removing some molecular organic impurities so that ionic impurities can be removed subsequently. In addition, sodium hydroxide can also effectively remove residual silicon powder on the surface of the monocrystalline silicon wafer (as shown in Formula II) or remove residual iron ions, copper ions and other metal ions on the surface of the monocrystalline silicon wafer through precipitation or complexation reactions. Furthermore, alkyl glycosides are also biodegradable and have virtually no pollution to the environment. After cleaning in the second cleaning tank, the silicon wafer can be rinsed again with pure water in the third cleaning tank to remove residual cleaning reagents and impurities such as sodium silicate on the surface of the monocrystalline silicon wafer, preparing it for the subsequent deep cleaning (deep oxidation of ionic impurities). In the fourth cleaning tank 1 used for deep cleaning, the first tank 11, the second tank 12, and the third tank 13 each contain a cleaning solution containing hydrogen peroxide. Under illumination, the doped graphene on the composite plate 4 located in the first tank 11 undergoes a redox reaction with hydrogen peroxide, generating hydroxyl radicals (·OH). Hydroxyl radicals are highly efficient oxidants that can react with ionic impurities on the surface of the silicon wafer, converting them into soluble substances, thereby achieving deep cleaning. Simultaneously, hydroxyl radicals (·OH) are generated... Hydroxyl radicals (OH) can oxidize heavy metal ions on the surface of monocrystalline silicon wafers into precipitates or more easily processed forms. These ions are then removed from the silicon wafer surface through cleaning (combined with bubbling, etc.). Furthermore, the design of the first and second anti-free radical oxidation reverse osmosis membranes and the high-pressure delivery device ensures that the generated high concentration of hydroxyl radicals can be transported with water molecules from the first tank 11 and the third tank 13 to the second tank 12, deeply purifying the silicon wafer. Simultaneously, it prevents substances from the intermediate tanks from flowing back into the first and second tanks, avoiding secondary contamination within the first and third tanks 11 and 13. Therefore, the cleaning solution in the first and third tanks 11 and 13 can be reused continuously, and only needs to be used when necessary. The cleaning solution in the second tank 12 only needs to be replaced, reducing the consumption of sodium hydroxide and hydrogen peroxide and lowering cleaning costs. Furthermore, the design employing the first anti-free radical oxidation reverse osmosis membrane 2 and the second anti-free radical oxidation reverse osmosis membrane 3 allows for control of the cleaning efficiency of the monocrystalline silicon wafers in the second tank 12 by adjusting the hydrogen peroxide concentration in the first tank 11 and the third tank 13, resulting in a highly controllable and stable cleaning process. Finally, in the fourth cleaning tank 1, the synergistic effect of hydrogen peroxide and the hydroxyl radicals catalyzed by the graphene-doped composite plate significantly improves the cleanliness of the monocrystalline silicon wafer surface, making it particularly suitable for silicon wafer cleaning in semiconductor manufacturing and solar panel production, helping to improve product performance and yield. The monocrystalline silicon wafer cleaning system of this invention is simple to operate, uses simple cleaning solutions, and has low wastewater treatment costs, achieving effective cleaning of the monocrystalline silicon wafer surface while maintaining low cleaning costs.

[0033] C x H y O z +NaOH→C x H y-1 O z Na+H2O(I); Si+2NaOH+H2O=Na2SiO3+2H2↑(II).

[0034] In some embodiments, at least one air bubbling device 5 is provided in the first tank 11, the second tank 12 and the third tank 13 respectively.

[0035] In the technical solution of this application embodiment, by setting an air bubbling device 5 in the second tank 12, the turbulence of the cleaning fluid can be increased, which is conducive to the removal of impurities (ionic impurities) on the silicon wafer surface and improves the cleaning efficiency. It is especially suitable for continuous cleaning of single crystal silicon wafers in a large-scale production environment, and can significantly improve the cleaning speed and effect. In addition, the air bubbling in the first tank 11 and the third tank 13 can increase the fluidity of the system cleaning fluid, improve the generation efficiency and diffusion efficiency of hydroxyl radicals, and improve the cleaning effect. Preferably, each air bubbling device 5 is respectively set at the bottom of the first tank 11, the second tank 12 and the third tank 13, which is conducive to improving the cleaning effect and efficiency. Specifically, the bubbling device can be a tubular bubbling device, which includes a chemically resistant pipe (such as a PVC or PE pipe) and multiple micro-orifice nozzles installed on the pipe. It can evenly distribute bubbles along the bottom or side of the tank. The advantage of using this device is that it can be flexibly arranged according to the size and shape of the tank, ensuring that the entire tank can be well covered by bubbles, thus improving the uniformity and efficiency of cleaning. In order to avoid the interaction between bubbles bubbled from two adjacent bubbling nozzles, which would affect the flow and breakage of bubbles and thus affect the coverage of bubbles on the liquid surface, the spacing between two adjacent nozzles is preferably 10cm to 12cm.

[0036] In some embodiments, a first cover plate 111 is provided at the upper end of the first tank 11 and a first liquid inlet 112 is provided on the first cover plate 111; a second cover plate 131 is provided at the upper end of the third tank 13 and a second liquid inlet 132 is provided on the second cover plate 131; the high-pressure conveying device includes a first high-pressure pump and a second high-pressure pump, the first liquid inlet 112 is connected to the outlet of the first high-pressure pump, the second liquid inlet 132 is connected to the outlet of the second high-pressure pump, the first high-pressure pump delivers a first cleaning solution containing hydrogen peroxide aqueous solution to the first tank (11) and drives water molecules in the first cleaning solution containing hydrogen peroxide aqueous solution to pass through the first anti-free radical oxidation reverse osmosis membrane, the second high-pressure pump delivers a third cleaning solution containing hydrogen peroxide aqueous solution to the third tank 13 and drives water molecules in the third cleaning solution containing hydrogen peroxide aqueous solution to pass through the second anti-free radical oxidation reverse osmosis membrane 3; preferably, the first tank 11 and the first cover plate 111 are integrally sealed, and the third tank 13 and the second cover plate 131 are integrally sealed.

[0037] In some embodiments, each first light source 6 and each second light source 7 are independently selected from either an incandescent lamp or a xenon lamp. It is understood that other light sources capable of providing visible light that can be absorbed by graphene are also applicable to the present invention, and will not be listed here.

[0038] In some embodiments, in order to make full use of the light source energy for the doped graphene on the composite plate 4, each first light source 6 is disposed on the upper part of the first tank 11, and each second light source 7 is disposed on the upper part of the third tank 13; preferably, each composite plate 4 located in the first tank 11 is disposed perpendicular to the bottom of the first tank 11, and each composite plate 4 located in the third tank 13 is disposed perpendicular to the bottom of the third tank 13; more preferably, each composite plate 4 located in the first tank 11 is located below each first light source 6, and each composite plate 4 located in the third tank 13 is located below each second light source 7.

[0039] In some embodiments, the alkyl glycoside is selected from at least one of APG-1214 and dodecyl glucoside. Both APG-1214 and dodecyl glycoside are nonionic surfactants with good emulsifying, dispersing and cleaning properties, good biodegradability, and are environmentally friendly.

[0040] Doped graphene has more electrons and holes to provide more sites for redox reactions, and can generate a sufficient amount of hydroxyl radicals to meet the quality and efficiency requirements of single-crystal silicon wafer cleaning. In some embodiments, the doped graphene includes at least one of nitrogen-doped graphene and phosphorus-doped graphene. The use of N and phosphorus nonmetallic doping can generate NC bonds, and the C atoms adjacent to the N atoms will carry more positive charges, which can effectively enhance the electronegativity of the graphene material, which is beneficial to the redox reaction with hydrogen peroxide and increases the rate of free radical generation.

[0041] In some embodiments, each composite plate 4 further includes a polymer matrix, which includes at least one of polystyrene and polypropylene. Doped graphene is distributed on the surface of the polymer matrix to obtain higher cleaning efficiency and reduce cleaning costs. Preferably, the doped graphene can be bonded to the composite plate 4 by forming a coating or surface modification on the surface of the polymer matrix. Preferably, the doped graphene (e.g., nitrogen or phosphorus doped graphene) is chemically bonded to the composite plate by chemical modification methods, thereby firmly bonding to the composite plate 4. For example, common chemical modification methods such as acylation, hydroxylation and ammoniation can be used.

[0042] In some embodiments, the first anti-free radical oxidation reverse osmosis membrane 2 and the second anti-free radical oxidation reverse osmosis membrane 3 are respectively antioxidant polyamide reverse osmosis membranes. Phosphorus-based antioxidants, such as phosphites, can be introduced into the polyamide reverse osmosis membrane to enhance the membrane's antioxidant properties. These antioxidants reduce the oxidative degradation of the polyamide membrane material by inhibiting the chain reaction of free radicals.

[0043] In some embodiments, the monocrystalline silicon wafer cleaning system further includes an automatic turbidity monitoring system, which includes a yellow target, a CCD visual inspection probe and an image processing device, a first control device, a drainage device and a water filling device. The yellow marker is placed at the bottom of the first cleaning tank; The CCD visual inspection probe is used to acquire images of the yellow target and send them to the image processing device; The image processing device is used to receive an image of the yellow target and process the image of the yellow target to obtain the brightness value and the sharpness value of the yellow target, and then send them to the first control device. The first control device is used to receive the brightness value and clarity value of the yellow target and, when the brightness value and / or clarity value of the yellow target are lower than a preset value, control the drainage device to drain the first cleaning tank and, after the drainage device has drained the water, control the water filling device to add water to the first cleaning tank.

[0044] In the technical solution of this application embodiment, the automatic turbidity monitoring system can monitor the turbidity of the cleaning solution in real time and automatically control the replacement of pure water in the first cleaning tank. It is suitable for highly automated monocrystalline silicon wafer production lines, and can significantly reduce manual intervention, improve production efficiency and cleaning quality. Specifically, in this application, the yellow marker serves as a key reference in the automatic turbidity monitoring system, used by the CCD (charge-coupled device) visual inspection probe to monitor the water quality in the cleaning tank in real time. To ensure the accuracy of monitoring results and the stability of system operation, the yellow marker can be a specially made corrosion-resistant ceramic material with a stable yellow glaze or dye applied to its surface to ensure long-term color stability. Alternatively, it can be made of plastic materials such as high-density polyethylene (HDPE) or polytetrafluoroethylene (PTFE), which not only have good chemical stability but can also form a stable yellow surface by adding yellow masterbatch or pigment. Specifically, as one of the key components of the automatic turbidity monitoring system, the CCD vision inspection probe is used to acquire image information of the yellow marker at the bottom of the cleaning tank to determine the turbidity of the cleaning fluid. The CCD vision inspection probe has high resolution to ensure that it can clearly capture the details of the yellow marker, including changes in brightness and sharpness on the marker surface. The CCD vision inspection probe has signal transmission capabilities so that image information can be transmitted to the image processing device. For example, the CCD vision inspection probe and the image processing device can be connected using high-quality data cables and interfaces, such as USB 3.0, GigE Vision, and other high-speed data transmission interfaces. For example, Cognex's In-Sight series cameras or Basler's Ace series cameras can be preferred types of CCD vision inspection probes in this application. These cameras are widely used in industrial vision inspection, providing not only high-precision image acquisition but also chemical resistance, water and dust resistance, making them ideal for monitoring water quality in cleaning tanks. Furthermore, they support multiple data transmission standards, such as GigE Vision, enabling fast and stable transmission of image information to image processing devices for automatic turbidity monitoring and control.

[0045] In some embodiments, the cleaning solution containing alkaline substances and surfactants has a pH value of 11 to 12, and the concentration of alkyl glycosides in the cleaning solution containing alkaline substances and surfactants is 0.1% to 1% by weight.

[0046] In the technical solution of this application embodiment, the alkaline environment with a pH value of 11-12 and the synergistic effect of alkyl glycoside surfactants not only ensure the cleaning effect, but also reduce the consumption of chemical reagents and the residue of chemical substances on the single crystal silicon wafer, thereby reducing the cleaning cost.

[0047] In some embodiments, the monocrystalline silicon wafer cleaning system further includes an automatic pH monitoring system, which includes a pH sensor, a second control device, and an alarm device. A pH sensor is installed in the second cleaning tank to obtain the pH value of the cleaning solution containing alkaline substances and surfactants and send it to the second control device. The second control device is used to receive the pH value of the cleaning solution containing alkaline substances and surfactants, and to control the alarm device to sound an alarm when the pH value of the cleaning solution containing alkaline substances and surfactants exceeds the preset range.

[0048] In the technical solution of this application embodiment, when the pH value of the cleaning solution containing alkaline substances and surfactants in the second cleaning tank exceeds the preset range, an automatic alarm system is triggered. After manual addition of reagents, the pH value is confirmed to be within the preset range before the cleaning system can operate. The automatic pH monitoring system ensures the stability of the chemical properties of the cleaning solution, and is particularly suitable for processes requiring precise control of cleaning conditions, such as integrated circuit manufacturing. It can effectively avoid poor cleaning results caused by pH fluctuations, ensuring the stability and efficiency of the cleaning effect. Specifically, the pH sensor type in this application can be a solid-state pH sensor or an electrochemical pH sensor. Both types can withstand strongly alkaline environments, have high stability, and respond quickly, making them suitable for use in automatic control systems to monitor the pH value of the cleaning solution in real time. For example, pH sensors from HACH (USA) or WTW (Germany) are widely used in industrial pH monitoring, providing not only high-precision measurements but also chemical corrosion resistance, fast response, and easy integration.

[0049] In some embodiments, the hydrogen peroxide content in the first cleaning solution containing the hydrogen peroxide aqueous solution is 1% to 4% by weight, the hydrogen peroxide content in the third cleaning solution containing the hydrogen peroxide aqueous solution is 1% to 4%, and the hydrogen peroxide content in the second cleaning solution containing the hydrogen peroxide aqueous solution is 1% to 4%.

[0050] In the technical solution of this application embodiment, under the above concentration conditions, hydrogen peroxide can efficiently remove organic residues on the surface of silicon wafers by releasing hydroxyl radicals, thereby improving the surface cleanliness of silicon wafers. Moreover, at a concentration of 1% to 4%, the storage and use safety risks of hydrogen peroxide are low, while reducing the consumption of chemical reagents and lowering the overall cleaning cost.

[0051] In some embodiments, the monocrystalline silicon wafer cleaning system further includes an automatic hydrogen peroxide concentration monitoring system, which includes a first hydrogen peroxide online concentration analyzer, a second hydrogen peroxide online concentration analyzer, a third control device, a first hydrogen peroxide feeding device, and a second hydrogen peroxide feeding device. The first hydrogen peroxide online concentration analyzer is installed in the first tank 11 to obtain the concentration of hydrogen peroxide in the first cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device. The second hydrogen peroxide online concentration analyzer is installed in the third tank 13 to obtain the concentration of hydrogen peroxide in the third cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device. The third control device is used to obtain the concentration of hydrogen peroxide in the first cleaning solution containing hydrogen peroxide aqueous solution and, when it is lower than a preset value, control the first hydrogen peroxide feeding device to add hydrogen peroxide to the first tank 11; and to obtain the concentration of hydrogen peroxide in the third cleaning solution containing hydrogen peroxide aqueous solution and, when it is lower than a preset value, control the second hydrogen peroxide feeding device to add hydrogen peroxide to the third tank 13.

[0052] In the technical solution of this application embodiment, the hydrogen peroxide concentration is monitored in real time by an automatic hydrogen peroxide concentration monitoring system, which ensures the stability of the oxidant concentration and effectively improves the cleaning effect and production yield. Specifically, the first and second online hydrogen peroxide concentration analyzers can be independently selected from electrochemical or optical online concentration analyzers, providing high-precision real-time concentration measurement and strong adaptability to environmental factors. For example, the Orion Star A329 / MD and MPR E-Scan online hydrogen peroxide concentration analyzers from Orion in the United States not only meet the needs of real-time monitoring but also have high stability and low maintenance costs, ensuring the controllability and efficiency of the cleaning process.

[0053] According to another aspect of the present invention, a method for cleaning a single-crystal silicon wafer using the above-described single-crystal silicon wafer cleaning system is also provided, comprising the following steps: Step S1: Place the monocrystalline silicon wafer in the first cleaning tank for the first cleaning to remove particulate impurities from the monocrystalline silicon wafer; Step S2: Place the monocrystalline silicon wafer that has undergone the first cleaning into the second cleaning tank for a second cleaning to remove the grease and organic matter on the monocrystalline silicon wafer. Step S3: Place the monocrystalline silicon wafer that has undergone the second cleaning into the third cleaning tank for a third cleaning to remove impurities such as sodium silicate from the monocrystalline silicon wafer. Step S4: Place the monocrystalline silicon wafer that has undergone the third cleaning into the second tank for the fourth cleaning.

[0054] In the technical solution of this application embodiment, the monocrystalline silicon wafer is first pre-cleaned with pure water in a first cleaning tank to remove large particulate impurities and some soluble contaminants; then it enters a second cleaning tank for a second cleaning to remove most of the oily organic matter on the surface of the silicon wafer, while the strong alkalinity of sodium hydroxide decomposes some of the organic matter; subsequently, it is rinsed again with pure water in a third cleaning tank to remove residual cleaning reagents and impurities such as sodium silicate on the surface of the monocrystalline silicon wafer; finally, it enters a fourth cleaning tank to clean and remove ionic impurities on the surface of the monocrystalline silicon wafer, improving the cleanliness of the surface of the monocrystalline silicon wafer, which helps to improve the performance and yield of the product, and the process is simple, highly controllable and stable.

[0055] In order to achieve good cleaning results and improve cleaning efficiency, in some embodiments, the first cleaning time is 150s to 200s, the second cleaning time is 150s to 200s, the third cleaning time is 150s to 200s, and the fourth cleaning time is 100s to 250s.

[0056] In some embodiments, steps S1, S2, S3 and S4 are all performed at 20°C to 30°C. This temperature provides a better cleaning effect and can effectively reduce the damage to the silicon wafer surface caused by high temperature and strong chemical reactions, thereby improving the product yield and performance. Preferably, the cleaning is performed at room temperature, which results in lower cleaning costs.

[0057] In some embodiments, during the fourth cleaning process, air is blown into the first, second, and third tanks respectively to form bubbles in the first, second, and third tanks. The air flow rates for the first, second, and third tanks are 0.5 L / min. At this flow rate, a higher bubble density can be obtained, which can increase the fluidity of the cleaning solution in the system, improve the generation and diffusion efficiency of hydroxyl radicals, and enhance the cleaning effect.

[0058] Example 1

[0059] like Figure 1 As shown, a single-crystal silicon wafer cleaning system includes: A first cleaning tank for holding pure water; a second cleaning tank for holding a cleaning solution containing an alkaline substance and a surfactant; the alkaline substance is sodium hydroxide, and the surfactant is dodecyl glucoside; a third cleaning tank for holding pure water; and a fourth cleaning tank 1, which includes a first tank 11 for holding a first cleaning solution containing a hydrogen peroxide aqueous solution, a second tank 12 for holding a second cleaning solution containing a hydrogen peroxide aqueous solution, a third tank 13 for holding a third cleaning solution containing a hydrogen peroxide aqueous solution, six first light sources 6 for providing illumination to the first tank 11, and six second light sources 7 for providing illumination to the third tank 13. The first tank 11 and the second tank 12 are connected by a communication channel. The first tank 11 and the second tank 12 are connected by a first anti-free radical oxidation reverse osmosis membrane 2, and the second tank 12 and the third tank 13 are connected by a second anti-free radical oxidation reverse osmosis membrane 3. At least one composite plate 4 is respectively provided in the first tank 11 and the second tank 12. Each composite plate 4 includes doped graphene. A high-pressure conveying device is used to convey a first cleaning solution containing hydrogen peroxide aqueous solution into the first tank 11 and drive water molecules in the first cleaning solution containing hydrogen peroxide aqueous solution through the first anti-free radical oxidation reverse osmosis membrane, and to convey a third cleaning solution containing hydrogen peroxide aqueous solution into the third tank 13 and drive water molecules in the third cleaning solution containing hydrogen peroxide aqueous solution through the second anti-free radical oxidation reverse osmosis membrane 3. At least one air bubbling device 5 is provided in each of the first tank 11, the second tank 12, and the third tank 13; each air bubbling device 5 is located at the bottom of the first tank 11, the second tank 12, and the third tank 13; a first cover plate 111 is provided at the upper end of the first tank 11, and a first liquid inlet 112 is provided on the first cover plate 111; a second cover plate 131 is provided at the upper end of the third tank 13, and a second liquid inlet 132 is provided on the second cover plate 131; the high-pressure conveying device includes a first high-pressure pump and a second high-pressure pump, the first liquid inlet 112 is connected to the outlet of the first high-pressure pump, and the second liquid inlet 132 is connected to the outlet of the second high-pressure pump; each first light source 6 is located at the upper part of the first tank 11, and each second light source 6 is located at the lower part of the third tank 13. Source 7 is located at the top of the third tank 13; each composite plate 4 located in the first tank 11 is perpendicular to the bottom of the first tank 11, and each composite plate 4 located in the third tank 13 is perpendicular to the bottom of the third tank 13; each composite plate 4 located in the first tank 11 is located below each first light source 6, and each composite plate 4 located in the third tank 13 is located below each second light source 7; each first light source 6 and each second light source 7 are incandescent lamps; each composite plate 4 also includes a polymer matrix, the polymer matrix material is polystyrene, and graphene is doped and distributed on the surface of the polymer matrix; the first anti-free radical oxidation reverse osmosis membrane and the second anti-free radical oxidation reverse osmosis membrane 3 are respectively phosphite antioxidant modified polyamide reverse osmosis membranes.

[0060] The cleaning solution containing alkaline substances and surfactants has a pH value of 11.5, and the concentration of dodecyl glucoside in the cleaning solution containing alkaline substances and surfactants is 5% by weight. The first cleaning solution containing hydrogen peroxide aqueous solution has a hydrogen peroxide content of 3% by weight, the second cleaning solution containing hydrogen peroxide aqueous solution has a hydrogen peroxide content of 3%, and the third cleaning solution containing hydrogen peroxide aqueous solution has a hydrogen peroxide content of 3%.

[0061] The specific steps for cleaning monocrystalline silicon wafers using a monocrystalline silicon wafer cleaning system are as follows: The first step is to place the monocrystalline silicon wafer in the first cleaning tank for the first cleaning, which takes 180 seconds. The second step is to place the monocrystalline silicon wafer that has undergone the first cleaning into the second cleaning tank for a second cleaning, which takes 180 seconds. The third step is to place the monocrystalline silicon wafer that has been cleaned the second time into the third cleaning tank for a third cleaning, which takes 180 seconds. The fourth step is to place the monocrystalline silicon wafer that has undergone the third cleaning into the second tank 12 for a fourth cleaning, which takes 180 seconds.

[0062] All of the above cleaning steps were performed at room temperature. During the fourth cleaning process, air was blown into the first, second, and third tanks to form bubbles in the first, second, and third tanks respectively. The air flow rates blown into the first, second, and third tanks were 0.5 L / min.

[0063] Example 2

[0064] The only difference from Example 1 is that the pH value of the cleaning solution containing alkaline substances and surfactants is 11, and the concentration of dodecyl glucoside in the cleaning solution containing alkaline substances and surfactants is 0.1% by weight; the hydrogen peroxide content in the first cleaning solution containing hydrogen peroxide aqueous solution is 1% by weight, the hydrogen peroxide content in the second cleaning solution containing hydrogen peroxide aqueous solution is 1%, and the hydrogen peroxide content in the third cleaning solution containing hydrogen peroxide aqueous solution is 1%.

[0065] Example 3

[0066] The only difference from Example 1 is that the pH value of the cleaning solution containing alkaline substances and surfactants is 12, and the concentration of dodecyl glucoside in the cleaning solution containing alkaline substances and surfactants is 1% by weight; the hydrogen peroxide content in the first cleaning solution containing hydrogen peroxide aqueous solution is 4% by weight, the hydrogen peroxide content in the second cleaning solution containing hydrogen peroxide aqueous solution is 4%, and the hydrogen peroxide content in the third cleaning solution containing hydrogen peroxide aqueous solution is 4%.

[0067] Comparative Example 1

[0068] The only difference between it and Example 1 is that the second cleaning step was not performed.

[0069] Comparative Example 2

[0070] The only difference between it and Example 1 is that the fourth step of cleaning was not performed.

[0071] Cleaning effect test

[0072] (1) Carbon residue test: The cleaned monocrystalline silicon wafers were placed in pure water for ultrasonic cleaning. Then, the carbon content C1 in the cleaned pure water was tested using COD (chemical oxygen demand). At the same time, monocrystalline silicon wafers of the same batch that had not undergone any cleaning were used as the object and ultrasonically cleaned under the same conditions, and the carbon content C2 in the pure water was tested. Then, the carbon residue n on the surface of the cleaned monocrystalline silicon wafers was calculated (n=(C1 / C2×100%)). The specific results are shown in Table 1.

[0073] (2) Metal residue test: The content of metal ions on the surface of the monocrystalline silicon wafer after cleaning was tested by ICP-MS. At the same time, the content of surface metal ions was tested on the same batch of monocrystalline silicon wafers that had not undergone any cleaning operation. The content of metal ions on the surface of the monocrystalline silicon wafer before cleaning and the content of metal ions on the surface of the monocrystalline silicon wafer after cleaning are shown in Table 1.

[0074] (3) Turbidity test: Take the cleaned monocrystalline silicon wafer and place it in pure water for ultrasonic cleaning. Then test the turbidity T1 of the pure water after cleaning. See Table 1 for details. At the same time, take the monocrystalline silicon wafers of the same batch that have not undergone any cleaning operation as the object and perform ultrasonic cleaning under the same conditions. The turbidity of the pure water after cleaning is 8 NTU.

[0075] Table 1

[0076] As shown in Table 1, the monocrystalline silicon wafer cleaning system based on the present invention has excellent cleaning effects on the carbon residue and metal ion impurity content on the surface of monocrystalline silicon wafers after cleaning. It is suitable for silicon wafer cleaning in semiconductor manufacturing and solar panel production, which helps to improve product performance and yield. In addition, the consumption of alkaline substances such as sodium hydroxide, surfactants such as dodecyl glucoside and hydrogen peroxide is low, which reduces cleaning costs.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A single-crystal silicon wafer cleaning system, characterized in that, include: The first cleaning tank is used to hold pure water; A second cleaning tank is used to hold a cleaning solution containing an alkaline substance and a surfactant; the alkaline substance includes at least one of sodium hydroxide and potassium hydroxide, and the surfactant includes an alkyl glycoside. The third cleaning tank is used to hold pure water; The fourth cleaning tank (1) includes a first tank (11) for holding a first cleaning liquid containing a hydrogen peroxide aqueous solution, a second tank (12) for holding a second cleaning liquid containing a hydrogen peroxide aqueous solution, a third tank (13) for holding a third cleaning liquid containing a hydrogen peroxide aqueous solution, at least one first light source (6) for providing illumination to the first tank (11), and at least one second light source (7) for providing illumination to the third tank (13); the first tank (11) and the second tank (12) are connected by a first anti-free radical oxidation reverse osmosis membrane (2), and the second tank (12) and the third tank (13) are connected by a second anti-free radical oxidation reverse osmosis membrane (3); at least one composite plate (4) is respectively provided in the first tank (11) and the second tank (12); each composite plate (4) includes doped graphene; A high-pressure conveying device is used to convey the first cleaning liquid containing hydrogen peroxide aqueous solution into the first tank (11) and drive the water molecules in the first cleaning liquid containing hydrogen peroxide aqueous solution through the first anti-free radical oxidation reverse osmosis membrane, and to convey the third cleaning liquid containing hydrogen peroxide aqueous solution into the third tank (13) and drive the water molecules in the third cleaning liquid containing hydrogen peroxide aqueous solution through the second anti-free radical oxidation reverse osmosis membrane (3).

2. The single-crystal silicon wafer cleaning system according to claim 1, characterized in that, At least one air bubbling device (5) is respectively provided in the first tank (11), the second tank (12), and the third tank (13); and / or, The first tank (11) is provided with a first cover plate (111) at its upper end and a first liquid inlet (112) is provided on the first cover plate (111); the third tank (13) is provided with a second cover plate (131) at its upper end and a second liquid inlet (132) is provided on the second cover plate (131); the high-pressure conveying device includes a first high-pressure pump and a second high-pressure pump, the first liquid inlet (112) is connected to the outlet of the first high-pressure pump, and the second liquid inlet (132) is connected to the outlet of the second high-pressure pump.

3. The single-crystal silicon wafer cleaning system according to claim 2, characterized in that, Each of the air bubbling devices (5) is respectively disposed at the bottom of the first tank (11), the second tank (12) and the third tank (13).

4. The single-crystal silicon wafer cleaning system according to claim 1, characterized in that, Each of the first light source (6) and each of the second light sources (7) is independently selected from either an incandescent lamp or a xenon lamp.

5. The single-crystal silicon wafer cleaning system according to claim 1, characterized in that, Each of the first light sources (6) is disposed on the upper part of the first tank (11), and each of the second light sources (7) is disposed on the upper part of the third tank (13).

6. The single-crystal silicon wafer cleaning system according to claim 5, characterized in that, Each of the composite plates (4) located in the first tank (11) is arranged perpendicular to the bottom of the first tank (11), and each of the composite plates (4) located in the third tank (13) is arranged perpendicular to the bottom of the third tank (13).

7. The single-crystal silicon wafer cleaning system according to claim 6, characterized in that, Each composite plate (4) located in the first tank (11) is located below each of the first light sources (6), and each composite plate (4) located in the third tank (13) is located below each of the second light sources (7).

8. The single-crystal silicon wafer cleaning system according to claim 1, characterized in that, The alkyl glycoside is selected from at least one of APG-1214 and dodecyl glucoside; and / or, The doped graphene includes at least one of nitrogen-doped graphene and phosphorus-doped graphene; and / or, Each of the composite plates (4) further includes a polymer matrix, the polymer matrix comprising at least one of polystyrene and polypropylene, wherein the doped graphene is distributed on the surface of the polymer matrix; and / or, The first anti-free radical oxidation reverse osmosis membrane (2) and the second anti-free radical oxidation reverse osmosis membrane (3) are respectively anti-oxidation polyamide reverse osmosis membranes.

9. The single-crystal silicon wafer cleaning system according to any one of claims 1 to 8, characterized in that, The single-crystal silicon wafer cleaning system also includes an automatic turbidity monitoring system, which includes a yellow target, a CCD visual inspection probe and image processing device, a first control device, a drainage device and a water filling device. The yellow marker is placed at the bottom of the first cleaning tank; The CCD vision detection probe is used to acquire an image of the yellow target and send it to the image processing device; The image processing device is used to receive the image of the yellow target and process the image of the yellow target to obtain the brightness value and the sharpness value of the yellow target, and then send them to the first control device. The first control device is used to receive the brightness value and the clarity value of the yellow target, and when the brightness value and / or the clarity value of the yellow target are lower than a preset value, control the drainage device to drain the first cleaning tank, and control the water filling device to add water to the first cleaning tank after the drainage device has finished draining.

10. The single-crystal silicon wafer cleaning system according to any one of claims 1 to 8, characterized in that, The cleaning solution containing alkaline substances and surfactants has a pH value of 11 to 12, and the concentration of alkyl glycosides in the cleaning solution containing alkaline substances and surfactants is 0.1% to 1% by weight.

11. The single-crystal silicon wafer cleaning system according to claim 10, characterized in that, The single-crystal silicon wafer cleaning system also includes an automatic pH monitoring system, which includes a pH sensor, a second control device, and an alarm device. The pH sensor is installed in the second cleaning tank to obtain the pH value of the cleaning solution containing alkaline substances and surfactants and send it to the second control device. The second control device is used to receive the pH value of the cleaning solution containing alkaline substances and surfactants, and control the alarm device to sound an alarm when the pH value exceeds a preset range.

12. The single-crystal silicon wafer cleaning system according to any one of claims 1 to 8, characterized in that, By weight percentage, the first cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide, the third cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide, and the second cleaning solution containing hydrogen peroxide aqueous solution contains 1% to 4% hydrogen peroxide; and / or, The single-crystal silicon wafer cleaning system also includes an automatic hydrogen peroxide concentration monitoring system, which includes a first hydrogen peroxide online concentration analyzer, a second hydrogen peroxide online concentration analyzer, a third control device, a first hydrogen peroxide feeding device, and a second hydrogen peroxide feeding device. The first hydrogen peroxide online concentration analyzer is installed in the first tank and is used to obtain the concentration of hydrogen peroxide in the first cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device; The second hydrogen peroxide online concentration analyzer is installed in the third tank to obtain the concentration of hydrogen peroxide in the third cleaning solution containing hydrogen peroxide aqueous solution and send it to the third control device. The third control device is used to obtain the concentration of hydrogen peroxide in the first cleaning solution containing the hydrogen peroxide aqueous solution and, when it is lower than a preset value, control the first hydrogen peroxide feeding device to add hydrogen peroxide to the first tank; and to obtain the concentration of hydrogen peroxide in the third cleaning solution containing the hydrogen peroxide aqueous solution and, when it is lower than a preset value, control the second hydrogen peroxide feeding device to add hydrogen peroxide to the third tank.

13. A method for cleaning monocrystalline silicon wafers using the monocrystalline silicon wafer cleaning system according to any one of claims 1 to 12, characterized in that, Includes the following steps: Step S1: Place the monocrystalline silicon wafer in the first cleaning tank for the first cleaning. Step S2: Place the monocrystalline silicon wafer that has undergone the first cleaning into the second cleaning tank for a second cleaning. Step S3: Place the monocrystalline silicon wafer that has undergone the second cleaning into the third cleaning tank for a third cleaning. Step S4: Place the single-crystal silicon wafer that has undergone the third cleaning into the second tank for the fourth cleaning.

14. The method for cleaning single-crystal silicon wafers according to claim 13, characterized in that, The first cleaning time is 150s to 200s, the second cleaning time is 150s to 200s, the third cleaning time is 150s to 200s, and the fourth cleaning time is 100s to 250s. Steps S1, S2, S3, and S4 are all performed at 20°C to 30°C; and / or, During the fourth cleaning process, air is blown into the first tank, the second tank, and the third tank, respectively. The air flow rates for the first tank, the second tank, and the third tank are 0.5 L / min.

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