Silica sol with controllable particle size, and preparation method and application thereof

Abstract

The application discloses a kind of controllable silica sols of particle size and its preparation method and application, belong to nanometer material preparation field.The method includes: preparation of containing polyol, alkaline catalyst, particle size stabilizer and alkaline buffer precursor solution;Sub-step drop of organosilane, first preparation small particle size seed, then particle growth is carried out under pH 8.0~9.5;Intermittent drop of amino organosilane containing surface modification;Through screen and microporous filter membrane filtration.The obtained sol particle size is 10~200nm, PDI<0.1, Zeta potential absolute value is >60mV, metal impurity is <1ppm.Can be used for semiconductor etching liquid, chemical mechanical polishing liquid, coating additive or catalyst carrier.The application particle size is controllable, monodispersity is good, purity is high, and storage is stable.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation, and in particular to a silica sol with controllable particle size, its preparation method, and its application. Background Technology

[0002] Sol-gel silica is widely used in semiconductor etching solutions, chemical mechanical polishing (CMP) slurries, coatings, catalyst supports and other fields due to its excellent colloidal stability, high specific surface area, good dispersibility and chemical inertness. Especially in semiconductor manufacturing, sol-gel silica is used as an etching additive or polishing abrasive, and its particle size distribution and dispersion stability directly affect device performance and process yield.

[0003] Currently, the main methods for synthesizing sol-gel silica include silane hydrolysis, silicate ion exchange, and gas-phase methods. However, these methods generally suffer from the following problems: 1) Traditional hydrolysis is simple to operate, but it has a wide particle size distribution (PDI>0.2) and poor batch consistency, making it difficult to meet the high requirements of semiconductor processes for particle size uniformity; 2) In existing technologies, particle size is often controlled by adjusting parameters such as pH, temperature, and stirring speed. However, the control precision is limited, and metal ion contamination is easily introduced, making it difficult to guarantee the high purity requirements of semiconductor processes. 3) Some methods employ a seed growth strategy, but problems such as uneven reaction during seed preparation and uncontrolled particle size during secondary growth still exist; 4) Commercially available sol-gel silica products often require the addition of stabilizers to delay sedimentation, but their absolute zeta potential is low (usually below 40mV), resulting in insufficient long-term storage stability and a tendency to gel or precipitate. 5) In CMP processes, sol-gel silica, as an abrasive, needs to achieve both high removal rates and low surface damage. However, traditional monodisperse spherical colloidal silica suffers from low polishing efficiency. Particles with non-uniform surface charge distribution may achieve differentiated effects on different material surfaces during polishing through selective adsorption mechanisms.

[0004] In the prior art, aminopropyltriethoxysilane (APTES) is often used for amino modification of silica surfaces to reverse the surface charge. APTES-modified silica surfaces are positively charged, and the zeta potential can change from negative to +7.5mV to +41.0mV, which makes it suitable for electrostatically immobilizing negatively charged biomolecules or expanding application environments.

[0005] Therefore, there is an urgent need to develop a silica sol with controllable particle size and high dispersion, which can not only achieve precise control of different target particle sizes in the range of 10 to 200 nm, but also control the particle size distribution index of the resulting silica to below 0.1, and improve CMP polishing performance. Summary of the Invention

[0006] The purpose of this invention is to provide a silica sol with controllable particle size, its preparation method and application, in order to solve the problems of wide particle size distribution (PDI>0.2), poor batch consistency and difficulty in meeting the high requirements of semiconductor process for particle size uniformity in existing silica sols, and to improve CMP polishing performance.

[0007] In a first aspect, the present invention provides a method for preparing silica sol with controllable particle size, comprising the following steps: S1. Preparation of precursor solution: Add deionized water, polyol, alkaline catalyst, particle size stabilizer and alkaline buffer to the container, and mix thoroughly under stirring at 500-1000 rpm to obtain a precursor solution with a pH value of 10.0-12.5. S2. Preparation of small-particle-size seed solution: The precursor solution is continuously stirred and heated to 60-70℃. The first part of organosilane is slowly added dropwise to the high-speed stirred precursor solution at a dropping rate of 0.2-2 mL / min. After the addition is completed, the temperature is maintained and stirred for 2-4 hours to obtain the small-particle-size seed solution. S3. Sol particle growth: The mixed solution of organosilane and polyol in the second part is added to the small-diameter seed solution at a dropping rate of 0.5-5 mL / min. During the dropping process, the pH value of the solution system is maintained between 8.0 and 9.5 by using an alkaline buffer. After the dropping is completed, the solution is kept at 60-70℃ and stirred for 2-4 hours to obtain the main sol. S4. Surface modification: Add aminosilane coupling agent intermittently to the main sol at a rate of 0.5-2 mL / min, with an interval of 10-40 min, for a total of 3-5 additions; after each addition, keep the reaction at 60-70℃ for 20-40 min; to obtain crude sol-silica product. S5. Post-processing: Cool the crude product to room temperature, and then filter it through a 100-500 mesh sieve and a 0.1-0.45μm microporous membrane to obtain the silica sol product.

[0008] Preferably, the organosilane is selected from one or more combinations of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, aminopropyltriethoxysilane, and vinyltrimethoxysilane.

[0009] Preferably, the first part of the organosilane accounts for 10% to 40% of the total mass of the organosilane.

[0010] Preferably, the alkaline catalyst is one or more combinations of ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethylenediamine, and triethylamine, with a mass concentration of 10% to 28%.

[0011] Preferably, the particle size stabilizer is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, OP-10, Tween-80, and polyethylene glycol 600-8000, and the amount added is 1% to 4.0% of the total mass of organosilane.

[0012] Preferably, the polyol is one or a combination of ethylene glycol, propylene glycol, glycerol, diethylene glycol, and pentaerythritol, and the amount added is 0.5% to 1.2% of the total mass of the organosilane.

[0013] Preferably, the alkaline buffer is one or more combinations of ammonium chloride, potassium chloride, lithium hydroxide, and potassium hydroxide, and the amount added is 0.01% to 0.05% of the total mass of the organosilane.

[0014] Preferably, in step S4, the aminosilane coupling agent includes aminopropyltriethoxysilane and aminopropyltrimethoxysilane.

[0015] Preferably, the amount of aminosilane coupling agent added is 6% to 12% of the total mass of the organosilane.

[0016] Preferably, in step S5, the filtration process is carried out under nitrogen protection, and the filtered product is concentrated using an ultrafiltration membrane to obtain a sol-silica product with a solid content of 10% to 30%.

[0017] Secondly, the present invention also provides a silica sol with a particle size of 10-200 nm, a particle size distribution index (PDI) of less than 0.1, an absolute value of zeta potential greater than 60 mV, a content of Li, K, and Na elements of less than 1 ppm, a SiO2 content of greater than or equal to 99.9998%, a sphericity of greater than or equal to 0.98, and a whiteness of greater than 97.5.

[0018] Thirdly, the present invention also provides the application of silica sol in semiconductor etching solutions, chemical mechanical polishing solutions, coating additives or catalyst supports.

[0019] The beneficial effects of this invention are: 1. The present invention has strong controllability of particle size and low dispersion. By adding organosilane in stages and combining it with seed pre-processing, it is possible to achieve precise control of different target particle sizes in the range of 10 to 200 nm. The particle size distribution index (PDI) of the resulting sol silica can be controlled below 0.1, with good monodispersity and high batch repeatability.

[0020] 2. This invention introduces a particle size stabilizer with a specific structure and a polyol to synergistically increase the zeta potential of the sol and enhance its electrostatic stabilization, allowing it to be stored at room temperature for more than a year without sedimentation. It is suitable for long-term storage and long-distance transportation, and does not require expensive equipment or complex purification steps. The reaction conditions are mild and the operation process is simple, making it suitable for large-scale continuous production.

[0021] 3. The amino groups introduced by intermittent surface modification in this invention generate a strong electrostatic repulsion force on the particle surface, with an absolute value of the Zeta potential greater than 60mV, effectively preventing particle aggregation. On the other hand, the surface organic modification layer can also prevent the chemical bonding of silanol groups between particles, ensuring the stability of the sol during long-term storage. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the silica sol synthesized in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the silica sol synthesized in Example 2 of the present invention; Figure 3 This is a scanning electron microscope image of the silica sol synthesized in Example 3 of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] A method for preparing silica sol with controllable particle size includes the following steps: S1. Preparation of precursor solution: Add deionized water, polyol, alkaline catalyst, particle size stabilizer and alkaline buffer to the container, and mix thoroughly under stirring at 500-1000 rpm to obtain a precursor solution with a pH value of 10.0-12.5. S2. Preparation of small-particle-size seed solution: The precursor solution is continuously stirred and heated to 60-70℃. The first part of organosilane is slowly added dropwise to the high-speed stirred precursor solution at a dropping rate of 0.2-2 mL / min. After the addition is completed, the temperature is maintained and stirred for 2-4 hours to obtain the small-particle-size seed solution. S3. Sol particle growth: The mixed solution of organosilane and polyol in the second part is added to the small-diameter seed solution at a dropping rate of 0.5-5 mL / min. During the dropping process, the pH value of the solution system is maintained between 8.0 and 9.5 by using an alkaline buffer. After the dropping is completed, the solution is kept at 60-70℃ and stirred for 2-4 hours to obtain the main sol. S4. Surface modification: Add aminosilane coupling agent intermittently to the main sol at a rate of 0.5-2 mL / min, with an interval of 10-40 min, for a total of 3-5 additions; after each addition, keep the reaction at 60-70℃ for 20-40 min; to obtain crude sol-silica product. S5. Post-processing: Cool the crude product to room temperature, and then filter it through a 100-500 mesh sieve and a 0.1-0.45μm microporous membrane to obtain the silica sol product.

[0025] By employing the above technical solution, uniform crystal nuclei are rapidly formed in a high-pH environment during stage S2. Then, a low-pH environment in stage S3 inhibits new nucleus formation and promotes uniform seed growth. Finally, intermittent surface modification in stage S4 achieves particle surface functionalization and stabilization. This solution completely separates the nucleation and growth stages and precisely controls the reaction kinetics of each stage through a buffer system. It fundamentally solves the core problems of wide particle size distribution and poor batch-to-batch consistency in traditional methods, achieving precise particle size control within the 10–200 nm range, with PDI stably controlled below 0.1.

[0026] In some embodiments, the organosilane is selected from one or more combinations of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, aminopropyltriethoxysilane, and vinyltrimethoxysilane; The first part, organosilanes, accounts for 10% to 40% of the total mass of organosilanes.

[0027] By adopting the above technical solution, the organosilane is divided into two parts and added dropwise in sequence, which can control the dispersibility, growth process and particle size of silica.

[0028] In some embodiments, the alkaline catalyst is one or more combinations of ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethylenediamine, and triethylamine, with a mass concentration of 10% to 28%.

[0029] By adopting the above technical solutions and selecting organic bases or volatile inorganic bases as catalysts, rather than non-alkali metal hydroxides such as NaOH or KOH, pollution from metal ions such as sodium and potassium can be eliminated at the source. Furthermore, these catalysts have sufficient catalytic activity to ensure that the pH value of the precursor in the S2 stage can quickly reach 10.0 to 12.5, allowing organosilicon to rapidly hydrolyze and nucleate, forming a large number of uniform microseeds.

[0030] In some embodiments, the particle size stabilizer is one or more combinations of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, OP-10, Tween-80, and polyethylene glycol 600-8000, and the amount added is 1% to 4.0% of the total mass of the organosilane.

[0031] By adopting the above technical solutions, the particle size stabilizer can be rapidly adsorbed onto the surface of newly formed particles during seed nucleation and early growth stages through steric hindrance or electrostatic repulsion, effectively preventing hard agglomeration between particles. Its addition amount is precisely controlled within 4.0%, providing sufficient initial protection while avoiding the formation of a thick organic layer on the particle surface by excessive stabilizer, which could affect subsequent amino modification and the surface activity of the final product in applications such as CMP.

[0032] In some embodiments, the polyol is one or more combinations of ethylene glycol, propylene glycol, glycerol, diethylene glycol, and pentaerythritol, and the amount added is 0.5% to 1.2% of the total mass of the organosilane.

[0033] By adopting the above technical solutions, polyols play multiple synergistic roles in the reaction system. First, as a co-solvent, they increase the solubility of organosilanes in water, making the hydrolysis-condensation reaction more uniform. Second, their multiple hydroxyl groups can form hydrogen bonds with silanols, regulating the condensation reaction rate, guiding silica to grow isotropically, and increasing its sphericity. Finally, when mixed and added dropwise with organosilanes in the S3 stage, they can maintain the uniformity of the growth interface, prevent excessively high local concentrations, and further narrow the particle size distribution.

[0034] In some embodiments, the alkaline buffer is one or more combinations of ammonium chloride, potassium chloride, lithium hydroxide, and potassium hydroxide, and the amount added is 0.01% to 0.05% of the total mass of the organosilane.

[0035] By employing the above technical solution, in the S3 stage, as the organosilane hydrolyzes, the system pH naturally decreases. The buffer precisely counteracts this change, maintaining a stable pH within a mild and controllable range of 8.0–9.5. This pH window effectively inhibits secondary nucleation, ensuring that almost all added monomers are used for the growth of existing seeds, which helps achieve precise particle size control and narrow distribution (PDI < 0.1). The use of a buffer system free of metal ions, such as ammonium chloride, is also to ensure the ultra-high purity of the product.

[0036] In some embodiments, in step S4, the aminosilane coupling agent includes aminopropyltriethoxysilane and aminopropyltrimethoxysilane; The amount of aminosilane coupling agent added is 6% to 12% of the total mass of organosilane.

[0037] By adopting the above technical solution, the particles are surface-modified by intermittent dripping. The 20-40 min holding time after each dripping provides sufficient time for the uniform adsorption, directional hydrolysis and chemical condensation of silane molecules on the particle surface, avoiding self-aggregation and nucleation caused by excessively high local concentration due to continuous dripping.

[0038] In some embodiments, in step S5, the filtration process is carried out under nitrogen protection, and the filtered product is concentrated using an ultrafiltration membrane to obtain a sol-silica product with a solid content of 10% to 30%.

[0039] By employing the above technical solutions, nitrogen-protected filtration can prevent the product from absorbing CO2 from the air during purification, thus avoiding pH fluctuations and particle instability. The combination of filtration using a sieve and a microporous membrane effectively removes trace amounts of gel fragments and foreign particles that may be generated during the reaction. Further ultrafiltration concentration not only precisely increases the product's solids content to the required 10%–30% for the application, but also...

[0040] Example Example 1: Preparation of sol-gel silica with a particle size of approximately 50 nm S1. Preparation of precursor solution: Add 1500g of deionized water to a 2000mL four-necked flask, then add 0.8g of diethylene glycol, 3.2g of sodium dodecyl sulfate and 0.045g of ammonium chloride. Adjust the pH to 11.8 with 28% ammonia water. Mix at 800rpm for 30min to obtain the precursor solution.

[0041] S2. Preparation of small-particle-size seed solution: The temperature of the precursor solution was raised to 65℃, and 45g of methyltrimethoxysilane was added dropwise at a rate of 2mL / min. During the dropwise addition, the stirring speed was kept at 800rpm. After the dropwise addition was completed, the reaction was kept at 65℃ for 3h to obtain seed sol.

[0042] S3. Sol particle growth: 105g of methyltrimethoxysilane and 0.8g of diethylene glycol were added dropwise to the seed sol at an initial rate of 3mL / min. During the addition, 28% ammonia was added to maintain the pH of the system at 8.5. After the addition was completed, the mixture was kept at 65℃ for 3h to obtain the main sol.

[0043] S4. Surface modification: 10 g of aminopropyltriethoxysilane was intermittently added to the main sol at a rate of 2 mL / min, with an interval of 30 min between additions, for a total of 3 additions; after each addition, the mixture was kept at 65 °C for 30 min to obtain crude sol silica product.

[0044] S5. Post-processing: Cool the crude product to room temperature and filter it through a 200-mesh sieve and a 0.22μm microporous membrane to obtain a sol-gel silica product with a solid content of 18.5%.

[0045] Upon testing, the average particle size of the sol-gel silica was as follows: Figure 1 The wavelength is 51.3 nm, PDI is 0.068, Zeta potential is -63.5 mV, and the total content of metal impurities (Li, K, Na) is 0.8 ppm.

[0046] Example 2: Preparation of sol-gel silica with a particle size of approximately 100 nm S1. Preparation of precursor solution: Add 2000g of deionized water to a 3000mL four-necked flask, then add 1.2g of glycerol, 4.5g of OP-10 and 0.15g of potassium chloride. Adjust the pH to 12.2 with 25% tetramethylammonium hydroxide solution. Mix at 800rpm for 40min to obtain the precursor solution.

[0047] S2. Preparation of small-particle-size seed solution: The temperature of the precursor solution was raised to 68℃, and 60g of methyltrimethoxysilane was added dropwise at a rate of 1.5mL / min. During the dropwise addition, the stirring speed was kept at 700rpm. After the dropwise addition was completed, the reaction was kept at 68℃ for 4h to obtain seed sol.

[0048] S3. Surface modification: 240 g of tetraethyl orthosilicate and 1.2 g of glycerol were added dropwise to the seed sol at an initial rate of 5 mL / min. During the addition, the pH of the system was maintained at 8.5 by adding 25% tetramethylammonium hydroxide. After the addition was completed, the mixture was kept at 68℃ for 4 h to obtain the main sol.

[0049] S4. Surface charge patterning: 24 g of aminopropyltriethoxysilane was intermittently added to the main sol at a rate of 2 mL / min, with an interval of 30 min between additions, for a total of 3 additions; after each addition, the mixture was kept at 65 °C for 30 min to obtain crude sol-silica product.

[0050] S5. Post-processing: Cool the crude product to room temperature and filter it through a 300-mesh sieve and a 0.45μm microporous membrane to obtain a sol-silica product with a solid content of 25%.

[0051] Upon testing, the average particle size of the sol-gel silica was as follows: Figure 2The wavelength is 98.7 nm, PDI is 0.045, Zeta potential is -71.2 mV, and the total content of metal impurities (Li, K, Na) is 0.6 ppm.

[0052] Example 3: Preparation of sol-gel silica with a particle size of approximately 30 nm S1. Preparation of precursor solution: Add 800g of deionized water to a 1000mL four-necked flask, then add 0.3g of ethylene glycol, 2.0g of polyethylene glycol 2000 and 0.025g of ammonium chloride. Adjust the pH to 11.5 with 20% ethylenediamine solution. Mix at 600rpm for 25min to obtain the precursor solution.

[0053] S2. Preparation of small-particle-size seed solution: The temperature of the precursor solution was raised to 62℃, and 20g of dimethyldimethoxysilane was added dropwise at a rate of 3mL / min. During the dropwise addition, the stirring speed was kept at 600rpm. After the dropwise addition was completed, the reaction was kept at 62℃ for 2.5h to obtain seed sol.

[0054] S3. Sol particle growth: 30 g of dimethyldimethoxysilane was added dropwise to the seed sol at an initial rate of 4 mL / min. During the addition, 20% ethylenediamine was added to maintain the pH of the system at 8.5. After the addition was completed, the reaction was kept at 62℃ for 2.5 h to obtain the main sol.

[0055] S4. Surface modification: 5 g of aminopropyltriethoxysilane and 0.3 g of ethylene glycol were intermittently added to the main sol at a rate of 2 mL / min, with an interval of 30 min between additions, for a total of 3 additions; after each addition, the mixture was kept at 65 °C for 30 min to obtain crude sol silica product.

[0056] S5. Post-processing: Cool the crude product to room temperature and filter it through a 100-mesh sieve and a 0.1μm microporous membrane to obtain a sol-silica product with a solid content of 15.2%.

[0057] Upon testing, the average particle size of the sol-gel silica was as follows: Figure 3 The wavelength is 31.5 nm, PDI is 0.052, Zeta potential is -59.8 mV, and the total content of metal impurities (Li, K, Na) is 0.9 ppm.

[0058] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for preparing silica sol with controllable particle size, characterized in that, Includes the following steps: S1. Preparation of precursor solution: Add deionized water, polyol, alkaline catalyst, particle size stabilizer and alkaline buffer to the container, and mix thoroughly under stirring at 500-1000 rpm to obtain a precursor solution with a pH value of 10.0-12.

5. S2. Preparation of small-particle-size seed solution: The precursor solution is continuously stirred and heated to 60-70℃. The first part of organosilane is slowly added dropwise to the high-speed stirred precursor solution at a dropping rate of 0.2-2 mL / min. After the addition is completed, the temperature is maintained and stirred for 2-4 hours to obtain the small-particle-size seed solution. S3. Sol particle growth: The mixed solution of organosilane and polyol in the second part is added to the small-diameter seed solution at a dropping rate of 0.5-5 mL / min. During the dropping process, the pH value of the solution system is maintained between 8.0 and 9.5 by using an alkaline buffer. After the dropping is completed, the solution is kept at 60-70℃ and stirred for 2-4 hours to obtain the main sol. S4. Surface modification: Add aminosilane coupling agent intermittently to the main sol at a rate of 0.5-2 mL / min, with an interval of 10-40 min, for a total of 3-5 additions; after each addition, keep the reaction at 60-70℃ for 20-40 min; to obtain crude sol-silica product. S5. Post-processing: Cool the crude product to room temperature, and then filter it through a 100-500 mesh sieve and a 0.1-0.45μm microporous membrane to obtain the silica sol product.

2. The preparation method according to claim 1, characterized in that, The organosilane is selected from one or more combinations of tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, aminopropyltriethoxysilane, and vinyltrimethoxysilane. The first part of the organosilane accounts for 10% to 40% of the total mass of organosilane.

3. The preparation method according to claim 1, characterized in that, The alkaline catalyst is one or more of ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ethylenediamine, and triethylamine, with a mass concentration of 10% to 28%.

4. The preparation method according to claim 1, characterized in that, The particle size stabilizer is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, OP-10, Tween-80, and polyethylene glycol 600-8000, and the amount added is 1% to 4.0% of the total mass of organosilane.

5. The preparation method according to claim 1, characterized in that, The polyol is one or more of ethylene glycol, propylene glycol, glycerol, diethylene glycol, and pentaerythritol, and the amount added is 0.5% to 1.2% of the total mass of the organosilane.

6. The preparation method according to claim 1, characterized in that, The alkaline buffer is one or more of ammonium chloride, potassium chloride, lithium hydroxide, and potassium hydroxide, and the amount added is 0.01% to 0.05% of the total mass of the organosilane.

7. The preparation method according to claim 1, characterized in that, In step S4, the aminosilane coupling agent includes aminopropyltriethoxysilane and aminopropyltrimethoxysilane; The amount of aminosilane coupling agent added is 6% to 12% of the total mass of the organosilane.

8. The preparation method according to claim 1, characterized in that, In step S5, the filtration process is carried out under nitrogen protection, and the filtered product is concentrated using an ultrafiltration membrane to obtain a sol-silica product with a solid content of 10% to 30%.

9. A silica sol prepared by the method according to any one of claims 1 to 8, characterized in that, Its particle size is 10-200 nm, the particle size distribution index (PDI) is less than 0.1, the absolute value of the zeta potential is greater than 60 mV, the content of Li, K and Na elements is less than 1 ppm, the SiO2 content is greater than or equal to 99.9998%, the sphericity is greater than or equal to 0.98, and the whiteness is greater than 97.

5.

10. The silica sol according to claim 9, characterized in that, Applications in semiconductor etching solutions, chemical mechanical polishing solutions, coating additives, or catalyst supports.

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