CN114736654A - Spherical abrasive, preparation method and application thereof, and sapphire grinding fluid containing spherical abrasive - Google Patents
Spherical abrasive, preparation method and application thereof, and sapphire grinding fluid containing spherical abrasive Download PDFInfo
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- CN114736654A CN114736654A CN202210456119.4A CN202210456119A CN114736654A CN 114736654 A CN114736654 A CN 114736654A CN 202210456119 A CN202210456119 A CN 202210456119A CN 114736654 A CN114736654 A CN 114736654A
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/14—Anti-slip materials; Abrasives
- C09K3/1436—Composite particles, e.g. coated particles
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09G—POLISHING COMPOSITIONS; SKI WAXES
- C09G1/00—Polishing compositions
- C09G1/02—Polishing compositions containing abrasives or grinding agents
Abstract
The invention provides a spherical grinding material, a preparation method and application thereof, and a sapphire grinding fluid containing the spherical grinding material. The spherical grinding material is formed by mixing and sintering diamond micro powder, alumina powder and silica powder, and the diamond micro powder is consolidated in the spherical grinding material, so that the contact area between a diamond cutting acute angle and a sapphire wafer is increased. The invention also discloses sapphire grinding fluid which comprises the spherical grinding material, the diamond grinding material, a suspending agent, a lubricating agent, a pH regulator, a wetting agent, a dispersing agent, an antirust agent and water. The sapphire grinding fluid can improve the grinding efficiency and reduce the processing cost on the premise of ensuring the surface quality of the wafer. The sapphire substrate ground by the sapphire grinding fluid has low surface roughness, good flatness and no obvious scratch. The sapphire grinding fluid has very good application prospect and large-scale industrial popularization potential.
Description
Technical Field
The invention relates to a processing technology of sapphire crystal materials, in particular to a spherical grinding material, a preparation method and application thereof, and a sapphire grinding liquid containing the spherical grinding material.
Background
Sapphire is also called Al2O3The single crystal, commonly known as corundum, is a simple coordination type oxide crystal. The sapphire crystal has excellent optical property, mechanical property and chemical stability, high strength, high hardness and scouring resistance, can work under the severe condition of high temperature close to 2000 ℃, and is widely applied to infrared military devices, satellite space technology and window materials of high-strength laser. The sapphire crystal becomes a semiconductor GaN/Al for practical application due to the unique lattice structure, excellent mechanical property and good thermal property2O3Light Emitting Diodes (LEDs), large scale integrated circuits (SOI) and SOS, superconducting nanostructured films and the like. In recent years, with the development of modern science and technology, new requirements on the size and quality of sapphire crystal materials are continuously put forward.
Currently, a single high hardness diamond is generally used as an abrasive for grinding a sapphire wafer, and some prior arts have been studied on a grinding fluid and a grinding method, for example, as follows:
CN113334148A discloses a processing technology for a large-size sapphire plate surface, and the processing method comprises the following steps: by diameter
Coarse grinding with 300-400 granularity diamond grinding wheel
The diamond grinding wheel with the granularity of 2000 μm is semi-finely ground, and is finely ground by using diamond grinding fluid with the granularity of 4 μm, and is polished by using silicon dioxide polishing fluid. The processing requirement of large-size sapphire is met.
CN104493685A discloses a sapphire wafer processing method, which mainly adopts the principle that two diamond grinding liquids with different particle size distributions are combined with different grinding processes to adopt two-stage single-side grinding, firstly, the grinding liquid (coarse liquid) with larger particle size is used to quickly remove the thickness of the wafer surface, then, the grinding liquid (fine liquid) with smaller particle size is used to planarize the wafer surface, and simultaneously, the thickness of the damaged layer and the surface roughness of the wafer surface are reduced. The removal amount in the polishing process is reduced by using the sapphire grinding sheet with a low damage layer and no scratch after single-side grinding, so that the polishing process is simplified.
CN103013345A discloses an oily diamond grinding fluid and a preparation method thereof, wherein the grinding fluid comprises the following components: the diamond powder, a surfactant, a dispersant, a pH value regulator, a wetting agent and oil, wherein the weight ratio of each component is as follows: diamond micro powder: 0.001-10% of surfactant, 0.001-20% of dispersant, 0-10% of pH value regulator, 0-10% of wetting agent and the balance of oil. The polishing solution is mainly applied to the grinding and polishing of the surfaces of silicon carbide wafers, LED sapphire substrate sheets, ceramics, optical fibers, molds, semiconductor compound wafers and the like. The grinding fluid can greatly improve the polishing efficiency, has good dispersion performance, can keep a uniform and stable state for a long time, has high product smoothness after being polished, has good polishing effect, does not contain components harmful to human bodies, is easy to clean and is beneficial to environmental protection.
The prior art discloses some polishing liquids for sapphire substrates, but these polishing liquids still have some defects, such as: the diamond abrasive material is easy to settle, the grinding effect is poor, obvious scratches exist on the surface of the ground sapphire wafer, the obvious scratches are extremely difficult to remove in the back-end chemical mechanical polishing process, the grinding efficiency is not high, and the flatness of the ground sapphire wafer is also low.
Disclosure of Invention
The invention aims to provide a spherical grinding material, which is controllable in size and uniform in appearance, and increases the contact area between a diamond cutting acute angle and a sapphire wafer by solidifying diamond micro powder in the spherical grinding material, aiming at the problems that the existing diamond grinding material is easy to settle, the grinding effect of grinding liquid containing the diamond grinding material is poor, and the grinding efficiency is low; the sapphire grinding fluid containing the sapphire grinding fluid can keep stable suspension, has high grinding efficiency, low roughness value of processed wafers, good flatness and no obvious scratch, and is particularly suitable for grinding and thinning double sides and single sides of sapphire wafers.
In order to achieve the purpose, the invention adopts the technical scheme that: the spherical abrasive is prepared by the following method:
1) weighing three grinding materials according to the following mass ratio, namely alumina powder, silicon oxide powder and diamond micro powder in a ratio of 1:1:20-1:1:5, adding the mixed grinding materials into a stirring kettle, adding ethanol, and stirring to prepare slurry with solid content of 40-60 wt%;
2) adding 1-10g of adhesive polyvinyl butyral (PVB), 10-100g of polyethylene glycol 400, 10-50g of polymethyl acrylate and 1-10g of dodecyl hydroxypropyl sulfobetaine into 1kg of the slurry in sequence, and stirring to prepare mixed slurry;
3) ball-milling the mixed slurry obtained in the step 2);
4) carrying out spray granulation on the mixed slurry subjected to ball milling in the step 3), and sieving to obtain a spherical abrasive primary product;
5) drying the primary spherical abrasive obtained in the step 4) to remove the organic solvent;
6) placing the spherical abrasive primary product obtained in the step 5) in a sintering furnace, firstly performing vacuum sintering at 1800-2000 ℃ for 5-8h, performing high-temperature action to enable aluminum oxide and silicon oxide to generate phase change conversion to form a compact silicon-oxygen-aluminum composite material, tightly coating diamond micro powder, enabling the hardness of the spherical abrasive to be higher, then annealing in air at 1000-1200 ℃ for 10-12h, and removing residual organic matters through oxidation to prepare the spherical abrasive.
Further, the particle size of the alumina in the step 1) is 100-500 nm.
Further, the particle size of the silicon oxide in the step 1) is 100-500 nm.
Further, the grain diameter of the diamond micro powder in the step 1) is 200-1000 nm.
Further, the mass ratio of the alumina powder to the silica powder to the diamond micro powder in the step 1) is preferably 1:1:15-1:1: 10.
Further, step 1) produced a slurry of 50 wt% solids.
Further, step 2) preferably adds 5 to 10g of the binder polyvinyl butyral (PVB) per 1kg of slurry.
Further, step 2) preferably 10 to 50g of polyethylene glycol 400 per 1kg of slurry is added.
Further, step 2) preferably 10 to 30g of polymethyl acrylate per 1kg of the slurry is added.
Further, step 2) adds preferably 1 to 5g of dodecyl hydroxypropyl sulfobetaine per 1kg of slurry.
Further, the molecular weight of the polyvinyl butyral is 10000-100000.
Further, the molecular weight of the polyvinyl butyral is preferably 30000-50000.
Further, the polymethyl acrylate has a molecular weight of 1000-.
Further, the polymethyl acrylate preferably has a molecular weight of 1000-3000.
Further, the ball milling conditions in the step 3) are as follows: the planetary ball mill rotates at the speed of 200-300rpm, the grinding balls and the ball milling tank are made of high-purity alumina, the mass ratio of slurry to balls is 1:1, and the ball milling and mixing are carried out for 2-5 h.
Further, the ball milling mixing in step 3) is preferably carried out for 2 to 4 hours.
Further, a centrifugal spray dryer is adopted for spray granulation in the step 4).
The spray drying conditions were: the inlet temperature of hot air is 70-100 ℃, the outlet temperature is 40-60 ℃, the inlet air volume is 3-4L/min, and the outlet air volume is 2-3L/min; the rotating speed of the centrifugal atomizer is 8000-; the slurry pumping rate is 10-20 mL/min.
Further, in the step 4), the spherical powder obtained by spray granulation and collection is screened through 270-mesh and 1250-mesh screens by adopting an ultrasonic water screen, and the spherical abrasive in the middle section is taken.
Further, the drying temperature in the step 5) is 50-80 ℃.
Further, the drying time in the step 5) is 1-10 h.
Further, the drying temperature in the step 5) is preferably 60-80 ℃.
Further, the drying time in the step 5) is preferably 5-10 h.
Further, the particle size of the spherical abrasive is 12-50 μm.
Further, the spherical abrasive preferably has a particle size of 12 to 20 μm.
According to the invention, 200-plus-1000 nm diamond micro powder, alumina powder and silica powder are mixed and sintered, and the diamond micro powder is consolidated in the spherical grinding material by the spherical grinding material, so that the contact area between the diamond cutting acute angle and the sapphire wafer can be effectively increased.
The invention also discloses a sapphire grinding fluid which comprises the spherical grinding material.
Further, the spherical abrasive accounts for 10-20% of the sapphire grinding fluid by mass.
Further, the sapphire grinding fluid comprises the following components in parts by weight:
further, the spherical abrasive is preferably 0.5 to 0.8 parts.
Further, the diamond abrasive has a particle size of 3 to 9 μm.
Further, the diamond abrasive grain size is preferably 3 to 6 μm.
Further, the diamond abrasive is one or a mixture of several of polycrystalline diamond, polycrystalline diamond-like diamond and single crystal diamond.
Further, the diamond abrasive is preferably polycrystalline diamond.
Further, the diamond abrasive is preferably 0.1 to 0.3 parts.
Further, the mass ratio of the spherical abrasive to the diamond abrasive is 10:1-1: 1.
Further, the mass ratio of the spherical abrasive to the diamond abrasive is preferably 5:1 to 1: 1.
Further, the spherical abrasive and the diamond abrasive account for 0.5-2% of the sapphire grinding fluid by mass.
Further, the mass percentage of the spherical abrasive and the diamond abrasive in the sapphire grinding fluid is preferably 1.5-2%.
Further, the suspending agent is one or more of propylene glycol sodium alginate, hydroxypropyl starch, Arabic gum, pectin, agar, carrageenan, methylcellulose, carboxymethylcellulose, hydroxyethyl cellulose, organic bentonite and carboxyvinyl copolymer.
Further, the molecular weight of the carboxyvinyl copolymer is 5-10 ten thousand.
Further, the molecular weight of the carboxyvinyl copolymer is preferably 5 to 8 ten thousand.
Further, the suspending agent is preferably hydroxyethyl cellulose.
Further, the suspending agent is preferably 1 to 3 parts.
Further, the lubricant is one or more of glycerol, acetone glycerol, pentanediol, tripropylene glycol, hexylene glycol, sorbitol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, triethylene glycol monobutyl ether and neopentyl glycol.
Further, the lubricant is preferably sorbitol.
Further, the lubricant is preferably 10 to 20 parts.
Further, the pH regulator is one or more of triethanolamine, 2, 4-lutidine, diethanolamine, diglycolamine, triethylamine, ethylenediamine, isopropanolamine, p-aminophenol, tetramethylethylenediamine, triethylenediamine and tetramethylammonium hydroxide.
Further, the pH regulator is preferably triethylene diamine.
Further, the pH adjusting agent is preferably 5 to 10 parts.
Further, the wetting agent is one or more of tween 80, tween 60, sodium alkylphenol ether sulfosuccinate, sodium diisooctyl sulfosuccinate, disodium nonylphenol ether sulfosuccinate monoester, disodium fatty alcohol polyoxyethylene ether sulfosuccinate monoester, dioctyl sodium sulfosuccinate, sodium diethylhexyl sulfosuccinate, disodium lauryl alcohol sulfosuccinate, dioctyl sodium sulfosuccinate, alkylphenol polyoxyethylene ether and sodium nonylphenol polyoxyethylene ether sulfate.
Further, the wetting agent is preferably sodium diethylhexyl sulfosuccinate.
Further, the wetting agent is preferably 0.5 to 2 parts.
Further, the dispersing agent is one or more of polyvinyl amine, polyacrylamide, sodium polyacrylate, ammonium polyacrylate, sodium tripolyphosphate and a vinylpyrrolidone/vinylimidazole copolymer (PVP/PVI).
Further, the molecular weight of the polyvinylamine is 5000-30000.
Further, the molecular weight of the polyvinylamine is preferably 5000-.
Further, the polyacrylamide has a molecular weight of 3000-10000.
Further, the molecular weight of the polyacrylamide is preferably 5000-10000.
Further, the sodium polyacrylate has a molecular weight of 3000-10000.
Further, the sodium polyacrylate preferably has a molecular weight of 5000-.
Further, the ammonium polyacrylate has a molecular weight of 3000-10000.
Further, the ammonium polyacrylate preferably has a molecular weight of 5000-.
Further, the sodium tripolyphosphate and the vinylpyrrolidone/vinyl imidazole copolymer have the molecular weight of 5000-.
Further, the molecular weight of the sodium tripolyphosphate and the vinylpyrrolidone/vinylimidazole copolymer is preferably 5000-.
Further, the dispersant is preferably sodium polyacrylate.
Further, the dispersant is preferably 5 to 8 parts.
According to the invention, by adopting a scheme of combining the suspending agent and the dispersing agent, the viscosity of the sapphire grinding liquid system is increased, so that the spherical grinding material with the particle size of 12-50 mu m can be stably suspended, the contact time of the spherical grinding material with the sapphire is increased, the grinding speed is improved, and meanwhile, the wetting dispersing agent enables the diamond grinding material with the particle size of 3-9 mu m to be fully dispersed in the system through the synergistic effect of electrostatic repulsion and steric hindrance, so that the agglomeration and coagulation are avoided, the scratches on the surface of the sapphire are effectively eliminated, and the grinding quality of the surface of the sapphire is improved. For example, the sodium polyacrylate dispersant and the hydroxyethyl cellulose suspending agent are selected, the sodium polyacrylate dispersant contains abundant charged group carboxyl and has electrostatic repulsion, and the sodium polyacrylate dispersant and hydroxyl in the hydroxyethyl cellulose with a net structure form a winding adsorption state to form compact steric hindrance.
Further, the antirust agent is one or more of lauric acid, polyaspartic acid, glycine, tartaric acid, citric acid, glutamic acid, sebacic acid, salicylic acid, phenylalanine, 8-hydroxyquinoline, ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA).
Further, the rust inhibitor is preferably sebacic acid.
Further, the antirust agent is 0.1-0.3 part.
The sapphire grinding fluid comprises spherical grinding materials with the particle size of 12-50 mu m and diamond grinding materials with the particle size of 3-9 mu m, wherein the diamond grinding materials are adsorbed on the surface of the spherical grinding materials through electrostatic action, namely the diamond grinding materials are attached to the surface of the spherical grinding materials in the sapphire grinding fluid, so that the contact area between the sapphire grinding fluid and the diamond grinding fluid is further increased, and the grinding speed is improved. That is, the spherical abrasive in the polishing liquid for sapphire wafers of the present invention contains diamond fine powder inside, and also contains diamond abrasive, and the diamond abrasive preferentially participates in grinding during polishing, and as the spherical abrasive wears, the diamond fine powder inside is gradually exposed and participates in grinding. The spherical abrasive with diamond abrasive adsorbed on the surface enables the sapphire grinding fluid to have the grinding rate of the grinding fluid containing the conventional diamond abrasive, and meanwhile, deep scratches on sapphire are avoided.
The invention also discloses a preparation method of the sapphire grinding fluid, which comprises the following steps:
sequentially adding water, a dispersing agent, a lubricating agent, a wetting agent, an antirust agent and a pH regulator into a stirring kettle, and stirring and mixing to obtain a clear transparent solution;
step (2) adding a suspending agent into the solution obtained in step (1) under the stirring condition of 50-100rpm, and after the addition is finished, starting homogeneous stirring at 3000rpm for stirring for 10-60min to form uniform emulsion;
and (3) adding a spherical abrasive into the solution obtained in the step (2) under the stirring condition of 50-100rpm, stirring for 10-60min, then adding a diamond abrasive, and stirring for 10-60min to form a uniform suspension mixed solution, thereby completing the preparation of the sapphire grinding fluid.
Further, the stirring and mixing time in the step (1) is 10-20 min.
Further, the step (2) of turning on the homogeneous stirring is preferably 2000-3000 rpm.
Further, the stirring time in the step (2) is preferably 20 to 40 min.
Further, the spherical abrasive is added in the step (3), and the stirring time is preferably 30-60 min.
Further, diamond abrasive is added in the step (3), and the stirring time is preferably 30-60 min.
Further, the spherical grinding material in the step (3) is subjected to surface treatment before being added, and the surface treatment steps are as follows: adding the spherical grinding material into 5-40 wt% sulfuric acid aqueous solution, wherein the mass ratio of the spherical grinding material to the sulfuric acid aqueous solution is 1:10-1:40, soaking for 1-4h at 50-90 ℃, removing negative charges on the surface of the spherical grinding material, and washing for 2-4 times by using deionized water.
Further, in the step of treating the surface of the spherical abrasive, the spherical abrasive is added into a 5-10 wt% sulfuric acid aqueous solution.
Further, in the step of treating the surface of the spherical abrasive, the mass ratio of the spherical abrasive to the aqueous solution of sulfuric acid is 1:10 to 1: 20.
Further, in the step of treating the surface of the spherical abrasive, the soaking temperature is preferably 70-90 ℃.
Further, in the step of treating the surface of the spherical abrasive, the soaking time is preferably 2-4 h.
According to the invention, the surface of the spherical grinding material is treated before the sapphire grinding fluid is prepared, and the negative charges on the surface of the spherical grinding material are removed through strong acid, so that the surface of the spherical grinding material has more positive charges.
Further, the diamond abrasive material in the step (3) is subjected to surface treatment before being added, and the surface treatment steps are as follows: adding a diamond abrasive into a 1-10 wt% KOH aqueous solution, wherein the mass ratio of the diamond abrasive to the KOH aqueous solution is 1:20-1:50, soaking for 1-4h at 50-90 ℃ to enable the surface of the diamond abrasive to adsorb negative charges, and washing for 2-4 times by using deionized water; adding the cleaned diamond abrasive into 0.5-2 wt% of anionic surfactant solution, ultrasonically soaking for 1-4h at 10-40 ℃ to enable the surface of the diamond abrasive to adsorb enough anionic surfactant, and cleaning for 2-4 times by using deionized water to enable the surface of the diamond abrasive to have more negative charges.
Further, in the diamond abrasive surface treatment step, the diamond abrasive is added to a 5-10 wt% KOH aqueous solution.
Further, in the diamond abrasive surface treatment step, the mass ratio of the diamond abrasive to the KOH aqueous solution is 1:20-1: 30.
Further, in the step of processing the surface of the diamond abrasive, the surface of the diamond abrasive is soaked for 2 to 4 hours at the temperature of between 70 and 90 ℃ so that the surface of the diamond abrasive can absorb enough negative charges.
Further, in the diamond abrasive surface treatment step, the diamond abrasive after being cleaned is added into 1-2 wt% of an anionic surfactant solution.
Further, in the diamond abrasive surface treatment step, the ultrasonic temperature is preferably 15 to 35 ℃.
Further, in the diamond abrasive surface treatment step, the ultrasonic time is preferably 1-4 h.
According to the invention, the surface treatment is carried out on the diamond grinding material before the sapphire grinding fluid is prepared, and the surface of the diamond grinding material adsorbs enough anionic surfactant and has more negative charges. Further, the anionic surfactant is one or more of N-lauroyl potassium glutamate, sodium laureth carboxylate, magnesium laureth sulfate, sodium dodecyl benzene sulfonate, ammonium dodecyl sulfate and sodium lauryl polyoxyethylene ether sulfate.
The grinding fluid for the sapphire wafer is suitable for grinding and thinning the double sides and the single side of the sapphire wafer, and the specific use method is embodied in the embodiment.
The sapphire grinding fluid is also suitable for grinding and thinning processes of common hard and brittle materials, such as quartz glass, ceramic substrates, gallium arsenide substrates, indium phosphide substrates, integrated circuit chips, various gems, metal materials, hard alloys and the like, and can effectively improve the grinding efficiency and the grinding quality.
The usage and dosage of the sapphire grinding fluid are as follows:
grinding equipment: a wound double-side grinder 18 b;
the dosage of the grinding fluid: 1-5mL of each inch of sapphire sheet;
thickness of the ground sapphire wafer: 20-50 μm;
rotating speed: 30-50 rpm;
pressure: 800-;
temperature of the dish surface: 25-35 ℃;
grinding time: 10-30 min;
flow rate: 10-50 mL/min.
Compared with the prior art, the spherical grinding material and the sapphire grinding liquid have the following advantages:
1. according to the invention, the diamond micro powder, the alumina powder and the silica powder are mixed and sintered, and the diamond micro powder is consolidated in the spherical grinding material, so that the contact area between the diamond cutting acute angle and the sapphire wafer is increased. Simultaneously, diamond grinding materials are added into the grinding liquid and adsorbed on the surface of the spherical grinding materials through electrostatic action, so that the contact area of the diamond grinding materials and the sapphire is further increased, and the grinding speed is improved. That is, the inside of the spherical abrasive in the sapphire polishing liquid of the present invention is diamond fine powder, and the outside thereof is diamond abrasive, and the diamond abrasive preferentially participates in polishing during polishing, and as the spherical abrasive wears, the diamond fine powder inside the spherical abrasive gradually exposes and participates in polishing. The spherical grinding material with the diamond grinding material adsorbed on the surface ensures that the sapphire grinding fluid has the grinding rate of the grinding fluid containing the common diamond grinding material, and simultaneously avoids the deep scratch of the sapphire caused by the common diamond grinding material.
2. According to the method, before the grinding fluid is prepared, the surface of the spherical grinding material is treated, negative charges on the surface of the spherical grinding material are removed through strong acid, so that the surface of the spherical grinding material has more positive charges, meanwhile, the surface of the diamond grinding material is treated through surface treatment, sufficient anionic surfactant is adsorbed on the surface of the diamond grinding material, the surface of the diamond grinding material has more negative charges, the diamond grinding material and the spherical grinding material are adsorbed on the surface of the spherical grinding material through electrostatic adsorption, and in the grinding process, the diamond grinding material and the spherical grinding material are in full contact with a sapphire grinding surface, so that the grinding rate is increased.
3. Adopt the scheme that suspending agent and dispersant combine, through increasing sapphire lapping liquid system viscosity for the suspension can be stabilized to spherical abrasive material, increases the contact time to the sapphire, promotes the grinding rate, and wet dispersant passes through the synergism of electrostatic repulsion and steric hindrance simultaneously, makes the diamond abrasive material fully disperse in the system, avoids taking place to reunite and gather and sink, effectively eliminates the mar on sapphire surface, promotes the surperficial grinding quality of sapphire. For example, the sodium polyacrylate dispersant and the hydroxyethyl cellulose suspending agent are selected, the sodium polyacrylate dispersant contains abundant charged group carboxyl and has electrostatic repulsion, and the sodium polyacrylate dispersant and hydroxyl in the hydroxyethyl cellulose with a net structure form a winding adsorption state to form compact steric hindrance.
In conclusion, the sapphire grinding liquid has uniform dispersion and good chemical stability. The grinding liquid is adopted to grind the sapphire wafer, so that the grinding efficiency can be improved and the processing cost can be effectively reduced on the premise of ensuring the surface quality of the wafer. The sapphire substrate ground by the grinding fluid has low surface roughness, good flatness and no obvious scratch, has good rust-proof effect on the cast iron plate, and is easy to clean. The sapphire grinding fluid has very good application prospect and large-scale industrial popularization potential.
Drawings
FIG. 1 is an SEM image of a spherical abrasive prepared in example 3.
FIG. 2 is an EDS spectrum and element contents of the spherical abrasive prepared in example 3, wherein (a) is a scanning range diagram of the spherical abrasive and (b) is the content of each element.
FIG. 3 is a photograph of the polishing slurry of example 3 magnified 300 times under a microscope.
FIG. 4 is a photograph of the polishing slurry of example 3 magnified 100 times under a microscope.
Fig. 5 is a photograph of a scratch on the surface of sapphire observed under a microscope at a magnification of 500 times after the sapphire is ground, wherein (c) is comparative example 1 and (d) is example 3.
Fig. 6 is a photograph of pits or bumps on the surface of sapphire, which are observed under a microscope at a magnification of 500 times after the sapphire is ground, wherein (e) is comparative example 1 and (f) is example 3.
Detailed Description
The invention is further illustrated by the following examples:
examples 1 to 12
Examples 1-12 disclose various sapphire slurries having the components and weight ratios shown in table 1:
TABLE 1 compositions and weight ratios of sapphire slurries of examples 1-12
The spherical abrasives used in examples 1 to 12 were prepared by the following preparation method:
1) three abrasives were first weighed according to table 2: adding alumina powder, silicon oxide powder, diamond micropowder and 1kg of three grinding materials into a stirring kettle, adding 1kg of ethanol, and stirring for 10min to obtain uniform slurry;
2) sequentially adding PVB, polyethylene glycol 400, polymethyl acrylate and dodecyl hydroxypropyl sulfobetaine shown in the table 2 into 1kg of the slurry, and stirring at the rotating speed of 80rpm for 30min to prepare mixed slurry;
3) adding the mixed slurry obtained in the step 2) into a planetary ball mill, setting the ball milling rotation speed to be 300rpm, selecting high-purity alumina materials for a grinding ball and a ball milling tank, and carrying out ball milling and mixing for 3 hours to obtain mixed slurry, wherein the mass ratio of the slurry to the balls is 1: 1;
4) spray-granulating the mixed slurry obtained in step 3) with a centrifugal spray dryer (TR120AT-6HOP, PRECI K.K.; Japan); the spray drying conditions were: the inlet temperature of hot air is 70 ℃, the outlet temperature is 50 ℃, the inlet air volume is 3L/min, and the outlet air volume is 4L/min; the rotating speed of the centrifugal atomizer is 10000 rpm; the pumping speed of the slurry is 20mL/min, the collected spherical powder is screened by 270 meshes and 1250 meshes, and the spherical abrasive in the middle section is taken;
5) drying the spherical grinding material obtained in the step 4) in a drying oven at 50 ℃ for 8 hours, and drying the organic solvent;
6) placing the spherical grinding material obtained in the step 5) in a sintering furnace, sintering for 5h at 1800 ℃ in vacuum, and finally annealing for 10h in air at 1200 ℃ to obtain the spherical grinding material.
TABLE 2 examples 1-12 preparation of spherical abrasives with components and masses
FIG. 1 is an SEM image of a spherical abrasive prepared in example 3; the visible material is spherical, and the diamond micro powder is uniformly coated in the sphere. Fig. 2 is an EDS spectrum and element contents of the spherical abrasive prepared in example 3, wherein (a) is a schematic drawing of a scanning range of the spherical abrasive, and (b) is contents of respective elements, showing that the spherical abrasive contains silicon, aluminum and carbon elements, and is a composite sphere of silicon oxide, aluminum oxide and diamond micropowder. As shown in table 3, the spherical abrasive contains carbon element of diamond, aluminum element and silicon element of alumina and silica, confirming the synthesis of the spherical abrasive.
TABLE 3 elemental content of spherical abrasives
| Element(s) | By weight% | Atom% |
| C K | 54.97 | 64.36 |
| O K | 35.03 | 30.78 |
| Na K | 0.32 | 0.20 |
| Al K | 3.40 | 1.77 |
| Si K | 5.37 | 2.69 |
| K K | 0.41 | 0.15 |
| Ba L | 0.50 | 0.05 |
| Total amount of | 100.00 |
Examples 1-12 methods of preparing sapphire lapping liquids, comprising the steps of:
sequentially adding water, a dispersing agent, a lubricating agent, a wetting agent, an antirust agent and a pH regulator into a stirring kettle according to a ratio, stirring for 15min, and uniformly mixing to obtain a clear transparent solution;
step (2) adding the suspending agent into the solution obtained in the step (1) under the stirring of 80rpm, after the addition is finished, starting homogenizing and stirring at 2000rpm for 30min until uniform emulsion is formed;
step (3) under the stirring condition of 70rpm, gradually adding the spherical grinding material and the diamond grinding material subjected to surface treatment into the solution obtained in the step (2), stirring for 40min until the materials are uniformly mixed to form uniform suspension mixed liquid, and finishing the preparation of the sapphire grinding liquid;
wherein:
the surface treatment steps of the spherical abrasive material are as follows: adding the spherical grinding material into 10 wt% sulfuric acid aqueous solution, wherein the mass ratio of the spherical grinding material to the sulfuric acid aqueous solution is 1:20, soaking for 3 hours at 80 ℃, removing negative charges on the surface of the spherical grinding material, and washing for 3 times by using deionized water.
The surface treatment steps of the diamond abrasive are as follows: adding a diamond abrasive into 8 wt% KOH aqueous solution, wherein the mass ratio of the diamond abrasive to the KOH aqueous solution is 1:25, soaking for 3 hours at 80 ℃ to enable the surface of the diamond abrasive to adsorb enough negative charges, and washing for 3 times by using deionized water; adding the cleaned diamond abrasive into 1 wt% of N-lauroyl potassium glutamate solution, ultrasonically soaking for 3h at 20 ℃ to enable enough anionic surfactant to be adsorbed on the surface of the diamond abrasive, and cleaning for 3 times by using deionized water.
FIG. 3 is a photograph, at a microscopic magnification of 300 times, of the polishing slurry for a sapphire wafer of example 3, in which diamond abrasives are adsorbed on the surface of spherical abrasives. FIG. 4 is a photograph of the polishing slurry of example 3 magnified 100 times under a microscope. As can be seen from the figures 3 and 4, the diamond abrasive is adsorbed on the surface of the spherical abrasive, and the spherical abrasive and the diamond abrasive are uniformly suspended and distributed in the grinding liquid system, so that the contact time and the stress on the sapphire can be increased, and the grinding efficiency is improved.
Comparative examples 1 to 8
The components and weight ratios of the polishing slurry described in comparative examples 1 to 8 are shown in Table 4:
TABLE 4 composition and weight ratio of the grinding fluid of comparative examples 1 to 8
Comparative examples 2 to 4 used the same spherical abrasive as that prepared in example 3, comparative example 5 used 20 μm zirconia, comparative example 6 used a ceria-coated diamond hard core soft shell composite abrasive, comparative example 7 used 20 μm silica, and comparative example 8 used a silica sol.
The results of the performance tests of examples 1-12 and comparative examples 1-8 are shown in Table 5:
TABLE 5 results of performance tests of examples 1 to 12 and comparative examples 1 to 8
Analytical test methods of examples and comparative examples are as follows:
the polishing liquids prepared in examples 1 to 12 and comparative examples 1 to 8 were subjected to polishing tests using 2-inch sapphire sheets, and the removal rate, TTV, maximum scratch width, surface pit, and surface roughness were compared; and suspensibility for long standing (>30 days).
And (3) observing the surface quality after cleaning: firstly, using 3% cleaning solution to perform ultrasonic cleaning for 10min at 70 ℃ in two sections, then using deionized water to perform ultrasonic cleaning for 3min at 80 ℃, drying, and observing the surface quality under a microscope.
Maximum scratch width test after grinding: the cleaned sapphire sheet is tested for the maximum scratch width under the same magnification and visual field by using a microscope, and the maximum scratch width is respectively measured for 3 times to obtain an average value.
Post-grinding pit test: and observing the pit condition on the surface of the sapphire by using a microscope, judging that the sapphire is unqualified if small pits with the diameter of more than 10 mu m exist, and counting the percentage content of the pits.
And (3) grinding process:
grinding equipment: a manual double-side grinder 18 b;
size: 2 inch sapphire sheets;
number of test pieces: 160 pieces/disc;
rotating speed: 30 rpm;
pressure: 800 kg;
temperature of the dish surface: 25-35 ℃;
grinding time: 20 min;
flow rate: 20 mL/min.
Grinding test results:
as can be seen from the test data in Table 5, the removal rates for examples 1-12 are higher, about 1.5-2 times that of comparative examples 1-8; examples 1-12 were all lower in TTV, Ra, maximum scratch width, and 10 μm pit percentage than comparative examples 1-8 after grinding, indicating that examples 1-12 had better grinding results; and the examples 1-12 can still keep suspension after being placed for 30 days, while the comparative examples 1-8 can still keep suspension after being placed for 30 days, and a completely sunk hard precipitate is formed, so that the suspension can not be kept, which indicates that the suspension property of the examples 1-12 is better.
As shown in fig. 5 and 6, 2-inch sapphire sheets were polished using the polishing liquids of example 3 and comparative example 1, and fig. 5 is a photograph of a scratch on the sapphire surface observed under a microscope at a magnification of 300 times after sapphire polishing, wherein (c) is comparative example 1 and a significant scratch is observed; (d) in example 3, the scratch was remarkably slight. Fig. 6 is a photograph of pits or bumps on the surface of sapphire, which were observed under a microscope at a magnification of 500 times after grinding of sapphire, wherein (e) is comparative example 1, pits were clearly observed, and (f) is example 3, which was flat in surface and free of significant pits.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The spherical abrasive is characterized by being prepared by the following method:
1) weighing three abrasives according to the following mass ratio, namely alumina powder, silica powder and diamond micro powder in a ratio of 1:1:20-1:1:5, adding the mixed abrasives into a stirring kettle, adding ethanol, and stirring to prepare slurry;
2) adding 1-10g of adhesive polyvinyl butyral, 10-100g of polyethylene glycol 400, 10-50g of polymethyl acrylate and 1-10g of dodecyl hydroxypropyl sulfobetaine into 1kg of pulp in sequence, and stirring to prepare mixed pulp;
3) ball-milling the mixed slurry obtained in the step 2);
4) carrying out spray granulation on the mixed slurry subjected to ball milling in the step 3), and sieving to obtain a spherical abrasive primary product;
5) drying the primary spherical abrasive obtained in the step 4) to remove the organic solvent;
6) placing the spherical abrasive primary product obtained in the step 5) in a sintering furnace, firstly sintering the spherical abrasive primary product in vacuum at 1800-2000 ℃ for 5-8h, and then annealing the spherical abrasive primary product in air at 1000-1200 ℃ for 10-12h to prepare the spherical abrasive.
2. The spherical abrasive according to claim 1, wherein the spherical abrasive has a particle size of 12 to 50 μm.
3. A sapphire polishing slurry comprising the spherical abrasive according to claim 1 or 2.
4. The sapphire grinding fluid as set forth in claim 3, which comprises the following components in parts by weight:
5. the polishing slurry for sapphire wafers as set forth in claim 4, wherein the suspending agent is one or more selected from the group consisting of sodium alginate propylene glycol, hydroxypropyl starch, gum arabic, pectin, agar, carrageenan, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, organobentonite and carboxyvinyl copolymer.
6. The polishing slurry for sapphire wafers as set forth in claim 4, wherein the dispersant is one or more of polyvinylamine, polyacrylamide, sodium polyacrylate, ammonium polyacrylate, sodium tripolyphosphate and vinylpyrrolidone/vinylimidazole copolymer.
7. The sapphire abrasive liquid according to claim 4, wherein the diamond abrasive grains have a grain size of 3 to 9 μm.
8. A method for preparing the sapphire polishing slurry according to any one of claims 3 to 7, comprising the steps of:
sequentially adding water, a dispersing agent, a lubricating agent, a wetting agent, an antirust agent and a pH regulator into a stirring kettle, and stirring and mixing to obtain a clear transparent solution;
step (2) adding a suspending agent into the solution obtained in step (1) under the stirring condition of 50-100rpm, and after the addition is finished, starting homogeneous stirring at 3000rpm for stirring for 10-60min to form uniform emulsion;
and (3) adding a spherical abrasive into the solution obtained in the step (2) under the stirring condition of 50-100rpm, stirring for 10-60min, then adding a diamond abrasive, and stirring for 10-60min until the mixture is uniformly mixed to form a uniform suspension mixed solution, thereby completing the preparation of the sapphire grinding fluid.
9. The method for preparing the sapphire grinding fluid according to claim 8, wherein the spherical abrasive in step (3) is subjected to surface treatment before being added, and the surface treatment steps are as follows: adding the spherical grinding material into a 5-40 wt% sulfuric acid aqueous solution, wherein the mass ratio of the spherical grinding material to the sulfuric acid aqueous solution is 1:10-1:40, soaking for 1-4h at 50-90 ℃, removing negative charges on the surface of the spherical grinding material, and washing for 2-4 times by using deionized water.
10. The method for preparing the sapphire grinding fluid according to claim 8, wherein the diamond abrasive in the step (3) is subjected to surface treatment before being added, and the surface treatment steps are as follows: adding a diamond abrasive into a 1-10 wt% KOH aqueous solution, wherein the mass ratio of diamond powder to the KOH aqueous solution is 1:20-1:50, soaking for 1-4h at 50-90 ℃ to enable the surface of the diamond abrasive to adsorb enough negative charges, and washing for 2-4 times by using deionized water; adding the cleaned diamond abrasive into 0.5-2 wt% of anionic surfactant solution, ultrasonically soaking for 1-4h at 10-40 ℃ to enable the surface of the diamond abrasive to adsorb enough anionic surfactant, and cleaning for 2-4 times by using deionized water.
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