Silicon wafer cutting fluid and preparation method thereof
By using ferroferric oxide magnetic particles coated with graphite shells in the cutting fluid, the problems of high silicon wafer surface roughness and low cutting yield caused by diamond wire cutting fluid are solved, and a more efficient silicon wafer cutting effect is achieved.
Patent Information
- Application Number
- CN202510711391.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-09-23
Smart Images
Figure BDA0005427130330000081 
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a silicon wafer cutting fluid and a preparation method thereof. Background Art
[0002] In semiconductor manufacturing, silicon wafers, as the core substrate of integrated circuits, need to be cut from high-purity cylindrical silicon ingots. Traditional free abrasive wire saws are gradually being replaced by diamond wire cutting due to low efficiency and uneven thickness. Diamond wire cutting technology uses a high-speed reciprocating diamond particle coated metal wire (diamond wire) to directly cut silicon ingots. At the same time, spraying cutting fluid onto the diamond wire can increase the lubricity of the cutting interface, reduce frictional heat generated during cutting that causes warping or breakage of the silicon wafer, and can also remove a small amount of silicon debris accumulated between the diamond wire and the silicon wafer. However, the cutting fluid of the existing technology will cause the silicon wafer surface to be highly rough and have cutting line marks, especially when cutting large-sized silicon wafers such as 12 inches, the yield is low. Summary of the Invention
[0003] The main purpose of the present invention is to provide a silicon wafer cutting fluid and a preparation method thereof, aiming to solve the problem that the cutting fluid used in existing diamond wire cutting of silicon wafers causes high surface roughness of the silicon wafers and low yield when cutting large-size silicon wafers.
[0004] To achieve the above objectives, the present invention provides a silicon wafer cutting fluid, comprising magnetic particles, wherein the magnetic particles include a magnetic core and a graphite shell covering the magnetic core, wherein the magnetic core includes ferrosoferric oxide.
[0005] In one embodiment, the mass proportion of the magnetic particles in the silicon wafer cutting fluid is 1% to 10%; and / or,
[0006] The particle size of the magnetic core is 10 nm to 200 nm; and / or,
[0007] The particle size of the magnetic particles is 0.3 μm to 1 μm.
[0008] In one embodiment, the silicon wafer cutting fluid includes magnetic particles, an alkali, an organic acid, a chelating agent, a dispersant, a coolant, an antistatic agent, a sedimentation agent, a defoaming agent, and water.
[0009] In one embodiment, the silicon wafer cutting fluid includes, by mass percentage, 1% to 10% magnetic particles, 1.2% to 4% alkali, 1.8% to 11% organic acid, 0.4% to 1.5% chelating agent, 0.6% to 2.5% dispersant, 2% to 6% sedimentation agent, 0.2% to 1% defoaming agent, 0.4% to 1% antistatic agent and 4% to 10% coolant, with the balance being water.
[0010] In one embodiment, the base comprises, by mass percentage, one or more of sodium hydroxide, potassium hydroxide and triethanolamine; and / or,
[0011] The organic acid comprises one or more of citric acid, glycolic acid and benzoic acid; and / or,
[0012] The chelating agent includes one or more of disodium edetate, tetrasodium edetate and sodium gluconate; and / or,
[0013] The dispersant includes one or more of sodium polyacrylate, polyvinyl pyrrolidone and sodium dodecylbenzene sulfonate; and / or,
[0014] The coolant includes one or more of isopropyl alcohol, ethylene glycol and ethanol.
[0015] In one embodiment, the antistatic agent includes one or more of tetrabutylammonium fluoride, propylene acetate, and hexadecyltrimethylammonium chloride; and / or,
[0016] The sedimentation agent includes one or more of polyacrylamide, polyacrylic acid and polyamine; and / or,
[0017] The defoaming agent includes one or more of polyoxypropylene glycerol ether, acetylene alcohol defoaming agent and xylonic acid diester.
[0018] The present invention also provides a method for preparing the silicon wafer cutting fluid as described above, comprising the following steps:
[0019] S10, mixing an iron salt precursor, a ligand, a dispersant, and a reducing solvent, and performing a hydrothermal reaction to obtain Fe3O4 monodisperse particles;
[0020] S20, mixing Fe3O4 monodisperse particles with polyethylene glycol solution, functional monomer and initiator, drying and calcining to obtain graphite shell-coated Fe3O4 particles;
[0021] S30, mixing the graphite shell-coated Fe3O4 particles with alkali, organic acid, chelating agent, dispersant, sedimentation agent, coolant, defoaming agent, antistatic agent and water to obtain a silicon wafer cutting liquid.
[0022] In one embodiment, the iron salt precursor includes at least one of ferric chloride hexahydrate, ferric nitrate and ferric sulfate; and / or,
[0023] The complexing agent includes at least one of sodium acetate trihydrate, sodium citrate and sodium oxalate; and / or,
[0024] The dispersant comprises at least one of polyethylene glycol and polyvinyl pyrrolidone; and / or,
[0025] The reducing solvent includes at least one of ethylene glycol and glycerol.
[0026] In one embodiment, in step S10, the temperature of the hydrothermal reaction is 180° C. to 220° C., and the time of the hydrothermal reaction is 8 h to 10 h.
[0027] In one embodiment, in step S20:
[0028] The temperature of the mixing reaction is 70°C to 80°C; and / or,
[0029] The calcination temperature is 700° C. to 800° C.; and / or,
[0030] The mass ratio of the Fe3O4 monodisperse particles, the polyethylene glycol solution, the functional monomer and the initiator is 1:(18-22):(0.4-0.6):(0.05-0.15).
[0031] In the technical solution provided by the present invention, the outside of the magnetic particles is a graphite shell, and the graphite is soft. When the diamond wire is cut into silicon wafers, it has excellent lubricity, elasticity during extrusion, and lamellar sliding properties. Therefore, the lubricity of the diamond wire and the silicon ingot cutting interface can be improved. On the one hand, the impact force of the diamond particles set on the diamond wire on the silicon wafers on both sides of the cutting interface can be slowed down. On the other hand, it can be mixed in the silicon debris accumulated in the gaps of the silicon wafers and utilize its own volume and lubricity to improve the gaps and sliding between the silicon debris particles, so that most of the silicon debris can be taken away by the cutting fluid. In addition, since the graphite shell is coated with a magnetic core, it can be used to attract the silicon debris mixed with magnetic particles to leave the gap between the silicon wafer surface and the cutting interface during the cutting operation, further facilitating the silicon debris to be taken away by the cutting fluid. Therefore, the silicon wafer cutting fluid provided by the present invention uses the magnetic particles to not only improve the lubricity of the diamond wire and the silicon ingot cutting interface, but also to remove silicon debris, thereby reducing dynamic friction interference and reducing foreign matter damage sources, thereby reducing poor cutting line marks and improving cutting yield. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. Where the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0033] In semiconductor manufacturing, silicon wafers, as the core substrate of integrated circuits, need to be cut from high-purity cylindrical silicon ingots. Traditional free abrasive wire saws are gradually being replaced by diamond wire cutting due to low efficiency and uneven thickness. Diamond wire cutting technology uses a high-speed reciprocating diamond particle coated metal wire (diamond wire) to directly cut silicon ingots. At the same time, spraying cutting fluid onto the diamond wire can increase the lubricity of the cutting interface, reduce frictional heat generated during cutting that causes warping or breakage of the silicon wafer, and can also remove a small amount of silicon debris accumulated between the diamond wire and the silicon wafer. However, the cutting fluid of the existing technology will cause the silicon wafer surface to be highly rough and have cutting line marks, especially when cutting large-sized silicon wafers such as 12 inches, the yield is low.
[0034] In view of this, the present invention proposes a silicon wafer cutting fluid that can improve the lubricity of the cutting interface between the diamond wire and the silicon ingot and can also have a good silicon debris removal effect.
[0035] The preparation material of the silicon chip cutting fluid provided by the present invention includes magnetic particles, and the magnetic particles include a magnetic core and a graphite shell coated on the magnetic core, and the magnetic core includes ferroferric oxide. In the technical solution provided by the present invention, the outside of the magnetic particles is a graphite shell, and the graphite is soft. When the diamond wire cuts the silicon wafer, it has excellent lubricity, elasticity during extrusion, and lamellar sliding, so the lubricity of the diamond wire and the silicon ingot cutting interface can be improved, on the one hand, the impact force of the diamond particles arranged on the diamond wire on the silicon wafers on both sides of the cutting interface can be slowed down, and on the other hand, the silicon debris accumulated in the silicon wafer gap can be mixed with its own volume and lubricity to improve the gap and sliding between the silicon debris particles, so that most of the silicon debris can be taken away by cutting fluid. In addition, since the magnetic core is coated in the graphite shell, it is possible to use the external strong magnet suction during cutting operation to attract the silicon debris mixed with magnetic particles to leave the gap between the silicon wafer surface and the cutting interface, further facilitating the silicon debris to be taken away by cutting fluid. Therefore, the silicon wafer cutting fluid provided by the present invention uses the magnetic particles to not only improve the lubricity of the diamond wire and silicon ingot cutting interface, but also remove silicon debris, thereby reducing dynamic friction interference and reducing foreign matter damage sources, thereby reducing cutting line marks and improving cutting yield.
[0036] In the process of diamond wire cutting silicon wafers, if the micron-sized silicon debris generated by the cutting is not taken away in time, it may be entrained by the diamond wire and pressed back into the cutting seam. These hard debris will scratch the surface of the silicon wafer during high-speed movement, forming additional scratches or microcracks (i.e., secondary damage). In addition, the accumulation of debris will block the cutting seam, resulting in a sudden increase in local resistance. This resistance fluctuation may force the diamond wire to undergo transient deviation, resulting in uneven line marks or even breakage. Continuous debris removal can maintain the stability of the cutting resistance and ensure cutting uniformity. In the technical solution of the present invention, the use of the magnetic particles can not only improve the lubricity of the cutting interface between the diamond wire and the silicon ingot, but also remove silicon debris, thereby reducing dynamic friction interference and reducing the source of foreign matter damage, thereby reducing poor cutting line marks and improving cutting yield.
[0037] The magnetic core comprises ferroferric oxide, which has high magnetic responsiveness and good chemical stability. This allows it to more efficiently draw silicon debris containing magnetic particles away from the gap between the silicon wafer surface and the cutting interface during cutting operations, utilizing the strong external magnetic attraction. This further reduces defective cutting marks and improves cutting yield.
[0038] In some embodiments of the present invention, the mass proportion of the magnetic particles in the silicon wafer cutting fluid is 1% to 10%, the particle size of the magnetic core is 10nm to 200nm, and the particle size of the magnetic particles is 0.3μm to 1μm.
[0039] In some embodiments of the present invention, the silicon wafer cutting fluid comprises magnetic particles, an alkali, an organic acid, a chelating agent, a dispersant, a coolant, an antistatic agent, a sedimentation agent, a defoaming agent, and water. The neutralization reaction between the organic acid and the alkali in the silicon wafer cutting fluid system not only maintains a neutral pH to prevent damage to the cutting equipment, but also enhances the complexing capacity of the system, reducing the adsorption of silicon debris on the silicon wafer and its accumulation in the cut grooves on both sides of the silicon wafer, making the silicon debris more easily removed by the cutting fluid.
[0040] The chelating agent combines with the free metal ions through coordination bonds to form a stable water-soluble complex, which prevents the metal ions from being deposited on the surface of the silicon wafer or in the cutting fluid. The coolant quickly absorbs the heat generated during the cutting process (frictional heat between the diamond wire and the silicon wafer) through its high specific heat capacity or thermal conductivity, maintains the temperature of the cutting fluid stable, and prevents the silicon wafer from warping, microcracks or oxidation due to local overheating. The dispersant is adsorbed on the surface of silicon powder and abrasive particles through surface activity, forming electrostatic repulsion or steric hindrance, preventing particles from agglomerating, making the particles in the cutting fluid evenly suspended, and avoiding deposition blocking the cutting wire or scratching the surface of the silicon wafer. In addition, the silicon wafer cutting fluid system does not contain an auxiliary agent of phosphorus element, which is more environmentally friendly. The electrostatic agent can promptly eliminate the electrostatic charge generated by friction on the surface of the silicon wafer and diamond wire, reducing the problem of scratches or high roughness on the silicon wafer surface caused by electrostatic adsorption of silicon debris. After the cutting fluid cycle is completed (such as the recovery stage), the sedimentation agent promotes the aggregation of particles into large particles through charge neutralization or bridging, accelerates sedimentation, facilitates subsequent filtration or centrifugal separation, and realizes the recycling of the cutting fluid. Defoaming agents can reduce the surface tension of bubbles or inhibit bubble merging, thereby destroying the foam stability and reducing the foam generation in the cutting fluid, thereby reducing the interference of foam on the fluidity of the cutting fluid and reducing the impact of foam on cooling efficiency.
[0041] In some embodiments of the present invention, the silicon wafer cutting fluid includes, by mass percentage, 1% to 10% magnetic particles, 1.2% to 4% alkali, 1.8% to 11% organic acid, 0.4% to 1.5% chelating agent, 0.6% to 2.5% dispersant, 2% to 6% sedimentation agent, 0.2% to 1% defoaming agent, 0.4% to 1% antistatic agent and 4% to 10% coolant, with the balance being water.
[0042] In some embodiments of the present invention, the base includes one or more of sodium hydroxide, potassium hydroxide and triethanolamine; the organic acid includes one or more of citric acid, glycolic acid and benzoic acid; the chelating agent includes one or more of disodium edetate, tetrasodium edetate and sodium gluconate; the dispersant includes one or more of sodium polyacrylate, polyvinyl pyrrolidone and sodium dodecylbenzene sulfonate; the coolant includes one or more of isopropyl alcohol, ethylene glycol and ethanol.
[0043] In some embodiments of the present invention, the antistatic agent includes one or more of tetrabutylammonium fluoride, propylene acetate, and hexadecyltrimethylammonium chloride; the precipitant includes one or more of polyacrylamide, polyacrylic acid, and polyamine; and the defoamer includes one or more of polyoxypropylene glycerol ether, acetylenic alcohol defoamers, and xylonic acid diesters. These defoamers are non-silicone and will not precipitate from the cutting fluid, thus reducing the risk of silicone defoamer accumulating on the surface of the diamond wire and subsequently adhering to silicon debris.
[0044] The present invention also provides a method for preparing the silicon wafer cutting fluid as described above, the method comprising the following steps:
[0045] S10, mixing an iron salt precursor, a ligand, a dispersant, and a reducing solvent, and performing a hydrothermal reaction to obtain Fe3O4 monodisperse particles;
[0046] S20, mixing Fe3O4 monodisperse particles with polyethylene glycol solution, functional monomer and initiator, drying and calcining to obtain graphite shell-coated Fe3O4 particles;
[0047] S30, mixing the graphite shell-coated Fe3O4 particles with alkali, organic acid, chelating agent, dispersant, sedimentation agent, coolant, defoaming agent, antistatic agent and water to obtain a silicon wafer cutting liquid.
[0048] In some embodiments of the present invention, in step S10, the iron salt precursor includes at least one of ferric chloride hexahydrate, ferric nitrate and ferric sulfate; the ligand includes at least one of sodium acetate trihydrate, sodium citrate and sodium oxalate; the dispersant includes at least one of polyethylene glycol and polyvinyl pyrrolidone; and the reducing solvent includes at least one of ethylene glycol and glycerol.
[0049] In step S10, the iron salt precursor provides Fe 3+ The reducing solvent can not only reduce some of the ferric ions to ferrous ions, facilitating the subsequent formation of Fe3O4, but also provide an alkaline environment to dissolve the iron salt precursor and the ligand, forming a homogeneous reaction system, promoting ion migration and reaction uniformity. The ligand forms a stable complex with the iron ions, slowing down the hydrolysis rate and controlling the nucleation and growth kinetics. The dispersant is adsorbed on the particle surface, inhibiting agglomeration through electrostatic repulsion and steric hindrance to obtain monodisperse Fe3O4 particles.
[0050] In the specific preparation process, part of the reducing solvent can be mixed with the iron salt precursor and the ligand to obtain a mixed solution 1, part of the reducing solvent can be mixed with the dispersant to obtain a mixed solution 2, and then the mixed solution 1 and the mixed solution 2 are mixed to perform a hydrothermal reaction to obtain Fe3O4 monodisperse particles.
[0051] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 180° C. to 220° C., and the time of the hydrothermal reaction is 8 h to 10 h.
[0052] In step S20, polyethylene glycol (PEG) is adsorbed onto the surface of the monodisperse Fe3O4 particles through hydrogen bonding and steric hindrance. Simultaneously, functional monomers polymerize on the particle surface to form a crosslinked layer. After the reaction, the particles are centrifuged, washed with ethanol and deionized water to remove unreacted monomers, and freeze-dried to obtain PEG-coated Fe3O4 particles. Exemplarily, the PEG can be PEG4000. Exemplarily, the functional monomer can be ethylene glycol dimethacrylate. Exemplarily, the initiator can be ammonium persulfate.
[0053] In some embodiments of the present invention, the temperature for reacting the Fe 3 O 4 monodisperse particles with the polyethylene glycol solution, the functional monomer and the initiator is 70° C. to 80° C., and the reaction time is 4 to 6 hours.
[0054] In step S20, the PEG-coated Fe₃O₄ particles are calcined in an inert atmosphere to carbonize the PEG to form a graphite shell, thereby obtaining graphite-shell-coated Fe₃O₄ particles with a particle size of less than 1 micron. In some embodiments of the present invention, the calcination temperature is 700°C to 800°C, and the calcination time is 1.5 to 2.5 hours.
[0055] In some embodiments of the present invention, in step S20, the mass ratio of the Fe3O4 monodisperse particles, the polyethylene glycol solution, the functional monomer and the initiator is 1:(18-22):(0.4-0.6):(0.05-0.15).
[0056] In step S30, the graphite shell-coated Fe3O4 particles are mixed with an alkali, an organic acid, a chelating agent, a dispersant, a sedimentation agent, a coolant, a defoaming agent, an antistatic agent, and water to produce a silicon wafer cutting fluid. Exemplarily, the order of adding the ingredients may be: water, an alkali, an organic acid, a coolant, a chelating agent, a dispersant, a sedimentation agent, a defoaming agent, an antistatic agent, and the graphite shell-coated Fe3O4 particles. The particles may be uniformly dispersed using stirring or grinding equipment.
[0057] It should be noted that the method of using the silicon wafer cutting fluid is: directly using the cutting fluid without changing the existing cutting fluid use process, or using the cutting fluid after appropriately diluting it with water.
[0058] The technical solutions of the present invention are further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.
[0059] Example 1
[0060] Provided is a silicon wafer cutting fluid, which comprises 1% of magnetic particles, 1.2% of alkali, 1.8% of organic acid, 0.4% of chelating agent, 0.6% of dispersant, 2% of sedimentation agent, 4% of coolant, 0.2% of defoaming agent and 0.4% of antistatic agent, and the balance is water.
[0061] Preparation of magnetic particles (graphite shell coated Fe3O4 particles):
[0062] 1.624g of ferric chloride hexahydrate and 7.2g of sodium acetate trihydrate were dissolved in 50ml of ethylene glycol to obtain mixed solution 1. 2.000g of PEG4000 was dissolved in 20ml of ethylene glycol (heated and stirred until dissolved). Mixed solution 1 and mixed solution 2 were stirred and added to a hydrothermal reactor. After being kept at 200℃ for 8h, Fe3O4 monodispersed particles with a particle size of about 190nm were obtained. Under nitrogen protection, 1 mass part of the above The nanoparticles were dispersed in an aqueous solution of 20 parts by mass of polyethylene glycol 4000, and 0.5 parts by mass of a functional monomer (ethylene glycol dimethacrylate) and 0.1 parts by mass of an initiator (ammonium persulfate) were added and stirred evenly. The mixture was heated to 75°C and stirred for 5 hours. After the reaction, the mixture was centrifuged and washed with ethanol and deionized water, and freeze-dried to obtain PEG-coated nanoparticles. Monodisperse particles were calcined at 750°C in a nitrogen atmosphere for 2 hours to obtain graphite shell-coated Fe3O4 particles with a particle size of less than 1 micron.
[0063] Prepare silicon wafer cutting fluid:
[0064] The graphite shell-coated Fe3O4 particles are mixed with alkali, organic acid, chelating agent, dispersant, sedimentation agent, coolant, defoaming agent, antistatic agent and water according to the above mass percentages to obtain a silicon wafer cutting liquid.
[0065] Examples 2 and 3 and Comparative Examples 1-2 were prepared using similar steps to Example 1. The differences are shown in Table 1.
[0066] Table 1 Preparation materials and dosage of silicon wafer cutting fluids of Examples 1 to 3 and Comparative Examples 1 to 2
[0067]
[0068]
[0069] Performance Testing
[0070] The silicon wafer cutting fluids prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were used to cut 100 silicon wafers of 6 inches, 8 inches, and 12 inches, respectively, to obtain the average yield and surface roughness, which were recorded in Table 1 below.
[0071] Table 1 Test results of silicon wafer cutting fluids provided in Examples 1 to 3 and Comparative Examples 1 to 2
[0072]
[0073] As shown in Table 1, the silicon wafer cutting fluid prepared in Comparative Example 1 without the use of magnetic particles has a lower average yield than the silicon wafer cutting fluids prepared in Examples 1-3, and a higher roughness than the silicon wafer cutting fluids prepared in Examples 1-3. The silicon wafer cutting fluid prepared in Comparative Example 2 without the use of alkali and organic acid has a lower average yield than the silicon wafer cutting fluids prepared in Examples 1-3, and a higher roughness than the silicon wafer cutting fluids prepared in Examples 1-3. This indicates that the silicon wafer cutting fluid provided by the present invention reduces the amount of silicon debris adsorbed on the silicon wafer surface and accumulated in the cutting gap during use, thereby reducing adverse effects on the silicon wafer, thereby improving the cutting yield and reducing roughness.
[0074] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. A silicon wafer cutting fluid, characterized in that: The silicon wafer cutting fluid comprises magnetic particles, wherein the magnetic particles comprise a magnetic core and a graphite shell covering the magnetic core, and the magnetic core comprises ferrosoferric oxide.
2. The silicon wafer cutting fluid according to claim 1, wherein The mass proportion of the magnetic particles in the silicon wafer cutting fluid is 1% to 10%; and / or, The particle size of the magnetic core is 10 nm to 200 nm; and / or, The particle size of the magnetic particles is 0.3 μm to 1 μm.
3. The silicon wafer cutting fluid according to claim 1 or 2, wherein: The silicon wafer cutting fluid comprises magnetic particles, alkali, organic acid, chelating agent, dispersant, coolant, antistatic agent, sedimentation agent, defoaming agent and water.
4. The silicon wafer cutting fluid according to claim 3, wherein Measured in percentage by mass, the silicon wafer cutting fluid includes 1% to 10% magnetic particles, 1.2% to 4% alkali, 1.8% to 11% organic acid, 0.4% to 1.5% chelating agent, 0.6% to 2.5% dispersant, 2% to 6% sedimentation agent, 0.2% to 1% defoaming agent, 0.4% to 1% antistatic agent and 4% to 10% coolant, with the balance being water.
5. The silicon wafer cutting fluid according to claim 3 or 4, wherein: In terms of mass percentage, the base includes one or more of sodium hydroxide, potassium hydroxide and triethanolamine; and / or, The organic acid comprises one or more of citric acid, glycolic acid and benzoic acid; and / or, The chelating agent includes one or more of disodium edetate, tetrasodium edetate and sodium gluconate; and / or, The dispersant includes one or more of sodium polyacrylate, polyvinyl pyrrolidone and sodium dodecylbenzene sulfonate; and / or, The coolant includes one or more of isopropyl alcohol, ethylene glycol and ethanol.
6. The silicon wafer cutting fluid according to claim 3 or 4, wherein: The antistatic agent includes one or more of tetrabutylammonium fluoride, propylene acetate and hexadecyltrimethylammonium chloride; and / or, The sedimentation agent includes one or more of polyacrylamide, polyacrylic acid and polyamine; and / or, The defoaming agent includes one or more of polyoxypropylene glycerol ether, acetylene alcohol defoaming agent and xylonic acid diester.
7. A method for preparing a silicon wafer cutting fluid according to any one of claims 3 to 6, characterized in that: The following steps are involved: S10, mixing an iron salt precursor, a ligand, a dispersant, and a reducing solvent, and performing a hydrothermal reaction to obtain Fe3O4 monodisperse particles; S20, mixing Fe3O4 monodisperse particles with polyethylene glycol solution, functional monomer and initiator, drying and calcining to obtain graphite shell-coated Fe3O4 particles; S30, mixing the graphite shell-coated Fe3O4 particles with alkali, organic acid, chelating agent, dispersant, sedimentation agent, coolant, defoaming agent, antistatic agent and water to obtain a silicon wafer cutting liquid.
8. The method for preparing a silicon wafer cutting fluid according to claim 7, wherein: The iron salt precursor includes at least one of ferric chloride hexahydrate, ferric nitrate and ferric sulfate; and / or, The complexing agent includes at least one of sodium acetate trihydrate, sodium citrate and sodium oxalate; and / or, The dispersant comprises at least one of polyethylene glycol and polyvinyl pyrrolidone; and / or, The reducing solvent includes at least one of ethylene glycol and glycerol.
9. The method for preparing a silicon wafer cutting fluid according to claim 7, wherein: In step S10, the temperature of the hydrothermal reaction is 180° C. to 220° C., and the time of the hydrothermal reaction is 8 h to 10 h.
10. The method for preparing a silicon wafer cutting fluid according to claim 7, wherein: In step S20: The temperature of the mixing reaction is 70°C to 80°C; and / or, The calcination temperature is 700° C. to 800° C.; and / or, The mass ratio of the Fe3O4 monodisperse particles, the polyethylene glycol solution, the functional monomer and the initiator is 1:(18-22):(0.4-0.6):(0.05-0.15).