Preparation method of silica with controllable particle size and morphology
By using a feed redistributor below the liquid surface to control the feed position and method, the problem of controlling the particle size and morphology of silica sol was solved, improving the efficiency of the CMP process and product performance, and reducing production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
AI Technical Summary
Existing technologies struggle to effectively control the particle size and morphology of silica sol, and droplet splashing and uneven material distribution make nucleation reactions difficult, affecting the efficiency and cost of the CMP process.
By employing a feed redistributor that extends deep into the reaction system below the liquid surface, and controlling the feed location and method, the concentration distribution of reactants can be regulated, thereby achieving precise control over the particle nucleation and regrowth process.
It enables precise control over the particle size and morphology of silica sol particles, improving the efficiency of the CMP process and product performance, while reducing production costs.
Smart Images
Figure CN122144742A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nanomaterial preparation, specifically relating to a method for preparing silicon dioxide with controllable particle size and morphology, which can be used in the field of CMP polishing technology. Background Technology
[0002] Silica sol is a dispersion of nano-particle silica in water or other solvents. Due to the large number of silanol groups on its surface, it has high reactivity and is widely used in investment casting, papermaking, textiles, catalysts, carriers, coatings, semiconductor material polishing (CMP) and many other fields.
[0003] In chip manufacturing, hundreds of CMP (Chemical Motion Processing) steps are typically involved, and silica sol, as one of the main consumables in the CMP process, plays a crucial role. Due to the complexity and diversity of the entire CMP process, different CMP processes have different requirements for abrasives. Therefore, we need to effectively control the abrasive particle size, morphology, and purity to meet the diverse requirements of the entire CMP process for silica sol.
[0004] Existing technologies typically require stringent control of parameters in the silica sol synthesis process. This includes controlling the amount of catalyst added and the solution pH, or adding surfactants, alkali metal ions, and long-chain compounds to regulate the particle size and morphology of the silica sol. However, these control methods are difficult to implement, and the introduced substances are hard to eliminate in subsequent processing, negatively impacting application performance or making them unsuitable for large-scale production due to high costs. Furthermore, existing feeding methods often employ single-point feeding, primarily at the liquid surface. For nucleation reactions involving the transition from liquid to solid phase, droplets above the system cause splashing, and the redistribution of the feed liquid within the system is difficult to control, hindering the nucleation reaction. Summary of the Invention
[0005] To address the aforementioned problems, this invention innovatively proposes a method for preparing silica with controllable particle size and morphology. To achieve the objectives of this invention, the technical solution adopted is as follows:
[0006] This invention provides a method for preparing non-spherical colloidal silica, comprising the following steps:
[0007] 1) Mother liquor preparation: Mix organic solvent, alkaline catalyst, acid catalyst and water evenly;
[0008] 2) Preparation of solution B: Mix alkoxysilane with an organic solvent and stir for a period of time;
[0009] 3) Particle nucleation: Using a peristaltic pump, the feed redistributor is inserted into the mother liquor, and solution B is added to the mother liquor to carry out the silica particle nucleation reaction and obtain a seed solution;
[0010] 4) Particle regrowth: Add water and alkaline catalyst to the seed solution obtained in step 3) and stir until homogeneous; continue to add a mixture of alkoxysilane and organic solvent dropwise using a feed redistributor, and carry out particle regrowth under stirring;
[0011] 5) Concentration and filtration: The sample is heated and concentrated to remove the organic solvent, and then filtered to remove large particles.
[0012] In this invention, the mother liquor in step 1) contains 65%-85% organic solvent by mass, 13.5%-32% water by mass, 1%-3% alkaline catalyst by mass, and 10-1000 ppm acid catalyst by mass.
[0013] In this invention, the mass ratio of liquid B in step 2) to the mother liquor in step 1) is 1:9 to 1:5.
[0014] In this invention, the organic solvents used in steps 1) and 2) are selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether; preferably methanol.
[0015] In this invention, in steps 1) and 4), the alkaline catalyst is selected from one or more of alkali metal hydroxides, ammonia, organic amines, and basic amino acids; preferably, the alkaline catalyst is selected from one or more of potassium hydroxide, sodium hydroxide, triethanolamine, tetramethylamine hydroxide, lysine, and arginine; preferably, the alkaline catalyst used in steps 1) and 4) is the same.
[0016] In this invention, the acid catalyst in step 1) is selected from one or more of citric acid, malic acid, oxalic acid, maleic acid, tartaric acid, glutaric acid, adipic acid, malonic acid, succinic acid, fumaric acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, dimethylbutyric acid, hexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, and lactic acid; malic acid is preferred.
[0017] In this invention, the alkoxysilane mentioned in steps 2) and 4) is selected from one or more of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, preferably tetramethoxysilane;
[0018] In this invention, in step 2), the mass ratio of alkoxysilane to organic solvent in the mixture is 5:1 to 1:5; in step 4), the mass ratio of alkoxysilane to organic solvent in the mixture is 3:1 to 1:3, preferably 3:1 to 1:1.
[0019] In this invention, the amount of alkoxysilane added in step 4) is 8-25 times that in step 2).
[0020] In this invention, the amount of alkaline catalyst added in step 4) is 0.1-2 wt% of the seed crystal solution obtained in step 3), and the molar ratio of the amount of water added to the amount of alkoxysilane added in step 4) is 2-5:1.
[0021] In this invention, the feed redistributor described in steps 3) and 4) can be any one of the following: shower head-shaped, porous tubular, coil-shaped, or pagoda-shaped. The diameter of a single orifice is 0.1-10 mm, the number of orifices is 3-100, the linear velocity of the flow in a single orifice is 0.001-1 m / s, and the spacing between orifices is less than 3 cm.
[0022] In this invention, the feeding rates in steps 3) and 4) are 4.5-14.2 ml / min and 1.25-8 ml / min, respectively.
[0023] In this invention, the bottom of the feed redistributor described in steps 3) and 4) extends 5%-80% of the total height of the liquid surface in the entire system (measured from the bottom of the liquid surface).
[0024] Optionally, the feed redistributor can adjust its feed position according to the actual height of the liquid level.
[0025] Preferably, the particle nucleation reaction in step 3) is carried out at a temperature of 25-95℃.
[0026] Preferably, the particle regrowth in step 4) is carried out at a reaction temperature of 25-100℃, more preferably 60-90℃, and a stirring speed of 200-1000 r / min, more preferably 400-600 r / min.
[0027] The filtration described in step 4) has a filtration accuracy of 0.2-5μm, preferably using a PFA material filter element, and preferably employing two or three filtration stages.
[0028] In this invention, in step 5), the sample is preferably concentrated by constant liquid level heating solvent replacement and concentration, with a temperature of 50-150℃, preferably 90-130℃, and a pressure of 20-101Kpa.
[0029] The beneficial effects of this invention are as follows:
[0030] Compared with existing technologies, this invention alters the concentration distribution of reactants throughout the reaction process by controlling the feed redistributor's position below the liquid surface and its discharge method. Simultaneously, the nucleation process of silica sol particles involves a liquid-to-solid phase transition, which is relatively difficult. Inserting the feed pipe below the liquid surface, with the continuous introduction of liquid B, continuously disturbs the entire reaction system locally or in multiple locations, thereby enhancing the mass transfer process and reducing the difficulty of nucleation. Therefore, this invention employs a feed redistributor to further regulate the redistribution of reactants throughout the system, thereby creating different types of nucleation sites and achieving control over particle morphology and size. Attached Figure Description
[0031] Figure 1 TEM image of colloidal silica particles prepared in Example 1;
[0032] Figure 2 TEM image of colloidal silica particles prepared in Example 3;
[0033] Figure 3 TEM image of colloidal silica particles prepared in Comparative Example 1;
[0034] Figure 4 TEM image of colloidal silica particles prepared in Comparative Example 2;
[0035] Figure 5 TEM image of colloidal silica particles prepared in Comparative Example 3. Detailed Implementation
[0036] To better understand the technical solution of the present invention, the preparation method of the present invention will be further explained and illustrated below through more specific embodiments, but this does not constitute any limitation.
[0037] The main raw materials used in the following examples and comparative examples are as follows:
[0038] raw material factory Specification Ultrapure water Made using a Mili-Q Direct water purifier 18.2 MΩ·cm Ammonia solution (25% concentration) Suzhou Jingrui Chemical Co., Ltd. UP level methanol Suzhou Jingrui Chemical Co., Ltd. UP level ethanol Suzhou Jingrui Chemical Co., Ltd. UP level Isopropanol Suzhou Jingrui Chemical Co., Ltd. UP level Tetramethoxysilane Nantong Sojir 99.5％ Tetraethoxysilane Hubei New Blue Sky 99.3％
[0039] The detection method for the silica particles involved in this embodiment is as follows:
[0040] The test method for solid content is based on HGT 2521-2008 Industrial Silica Sol.
[0041] The secondary particle size of the silica sol particles was measured using a Malvern Zetasizer Nano ZS90 particle size analyzer. The primary particle size was determined using the BET surface area test method to obtain the specific surface area Sbet, with a primary particle size of 2727 / Sbet. The degree of association was calculated as the ratio of the secondary particle size to the primary particle size.
[0042] The surface morphology of the silica sol was characterized by TEM.
[0043] Example 1
[0044] After mixing 150g methanol, 3g ammonia, malic acid (containing 500ppm in the mother liquor) and 30.6g water evenly, the mixture was preheated at 25℃ to obtain mother liquor A.
[0045] A mixture of 19.19 g tetramethoxysilane and 5.1 g methanol was added dropwise to mother liquor A using a peristaltic pump. A shower-shaped feed redistributor was used, with 10 holes of 1 mm diameter each. The bottom of the redistributor penetrated 50% of the total height of the mother liquor into the liquid. The feed position remained unchanged throughout the dropping process. The feed rate was 4.71 ml / min, and the stirring speed was 400 r / min. After the dropping was completed, a seed solution was obtained.
[0046] Add 5g of ammonia and 73g of water to the seed crystal solution. At 75℃ and 360r / min, add 155g of a mixture of tetramethoxysilane and 155g of methanol dropwise to the seed crystal solution at a feed rate of 5ml / min. The bottom of the feed redistributor is 50% below the liquid surface of the seed crystal. The feed position remains unchanged throughout the dropwise process. After the dropwise process is completed, the initial silica sol is obtained.
[0047] Solvent replacement and concentration were carried out at a constant liquid level of 90 kPa and 130 °C. Water was added to the system while concentration and replacement were carried out until the methanol content in the system was less than 100 ppm, the solid content was more than 20 wt%, and the pH was 7.3. Then, the system was filtered through two stages using 1 μm and 0.3 μm PFA filter cartridges to remove large particles and obtain colloidal silica.
[0048] Example 2
[0049] After mixing 170g methanol, 2.85g ethylenediamine, 100ppm malic acid and 27g water evenly, the mixture was preheated at 95℃ to obtain mother liquor A.
[0050] A mixture of 6.4 g tetramethoxysilane and 32 g methanol was added dropwise to mother liquor A using a peristaltic pump. A shower-shaped feed redistributor was used, with 30 holes of 0.1 mm diameter each. The bottom of the feed redistributor penetrated 5% of the total height of the mother liquor. The feed position was continuously adjusted as the height of the mother liquor increased to always maintain a penetration position of 5% of the total height of the mother liquor. The feed rate was 10 ml / min, and the stirring speed was 400 r / min. After the addition was completed, a seed solution was obtained.
[0051] 2.47 g of ethylenediamine and 64 g of water were added to the seed crystal solution. At 65 °C and 500 r / min, a mixture of 160 g of tetramethoxysilane and 480 g of methanol was added dropwise to the seed crystal solution at a feed rate of 1.25 ml / min. The bottom of the feed redistributor was inserted into the liquid surface at a position of 30% of the total height of the mother liquor. The feed position was continuously adjusted as the height of the mother liquor increased. After the dropwise addition was completed, the initial silica sol was obtained.
[0052] Solvent replacement and concentration were carried out at a constant liquid level of 20 kPa and 50 °C. Water was added to the system while concentration and replacement were carried out until the methanol content in the system was less than 100 ppm, the solid content was more than 20 wt%, and the pH was 7.0. Then, the system was filtered through two stages using 1 μm and 0.3 μm PFA filter cartridges to remove large particles and obtain colloidal silica.
[0053] Example 3
[0054] After mixing 113.5g methanol, 5.3g ammonia, 1000ppm citric acid and 55.8g water evenly, the mixture was preheated at 40℃ to obtain mother liquor A.
[0055] A mixture of 19.19 g tetramethoxysilane and 3.84 g methanol was added dropwise to mother liquor A using a peristaltic pump. A porous rod-shaped feed redistributor was used, with each hole having a diameter of 10 mm and a total of 3 holes. The bottom of the redistributor penetrated 70% of the total height of the mother liquor into the liquid. The position of the feed tube remained unchanged throughout the dropping process. The feed rate was 14.2 ml / min, and the stirring speed was 600 r / min. After the dropping was completed, a seed solution was obtained.
[0056] Add 39.8g of ammonia and 35.8g of water to the obtained seed crystal solution. At 25℃ and 360r / min, add a mixture of 155g of tetramethoxysilane and 51.77g of methanol dropwise to the seed crystal solution at a feed rate of 3ml / min. The feed redistributor has a single hole diameter of 1mm and 10 holes. The bottom end of the redistributor is positioned at 70% of the total height of the mother liquor. The position of the feed tube remains unchanged throughout the dropwise process to obtain the initial silica sol.
[0057] 4) Solvent replacement and concentration were carried out at constant liquid level at 101 kPa and 150 °C. Water was added to the system while concentration and replacement were carried out until the methanol content in the system was less than 100 ppm, the solid content was more than 20 wt%, and the pH was 7.3. Then, the system was filtered through two stages using 1 μm and 0.3 μm PFA material filter cartridges to remove large particles and obtain dense irregular colloidal silica.
[0058] Example 4
[0059] Mix 98g isopropanol, 1.4g tetramethylammonium hydroxide, 10ppm malonic acid and 33g water until homogeneous, and preheat at 95℃ to obtain mother liquor A;
[0060] A mixture of 11.58 g tetraethoxysilane and 3.1 g isopropanol was added dropwise to mother liquor A using a peristaltic pump. A coil-type feed redistributor was used, with 100 holes of 0.5 mm diameter each. The bottom of the redistributor was inserted into the liquid to 80% of the total height of the mother liquor. The position of the feed tube remained unchanged throughout the dropping process. The feed rate was 4.5 ml / min, and the stirring speed was 400 r / min. After the dropping was completed, a seed solution was obtained.
[0061] Add 8.1g of tetramethylammonium hydroxide and 117g of water to the obtained seed crystal solution. At 95℃ and 1000r / min, add 275g of tetraethoxysilane and 275g of isopropanol mixture dropwise to the above seed crystal solution at a feed rate of 8ml / min. The bottom of the feed redistributor is inserted into the liquid surface to 80% of the total height of the mother liquor. The position of the feed tube remains unchanged throughout the dropwise process to obtain the initial silica sol.
[0062] 4) Solvent replacement and concentration were carried out at constant liquid level at 101 kPa and 130 °C. Water was added to the system while concentration and replacement were carried out until the isopropanol content in the system was less than 100 ppm, the solid content was more than 20 wt%, and the pH was 7.1. Then, the system was filtered through two stages using 1 μm and 0.3 μm PFA material filter cartridges to remove large particles and obtain dense irregular colloidal silica.
[0063] Comparative Example 1
[0064] The preparation method is the same as in Example 1, except that: the entire liquid feeding process of alkoxysilane uses a common single-point discharge feed pipe, and the feed pipe is inserted deep below the liquid surface, with the bottom of the pipe reaching 50% of the total height of the liquid surface. Other operations remain unchanged, and colloidal silica is obtained.
[0065] The colloidal silica prepared in this comparative example had an uneven silica sol morphology, with spherical particles accounting for a large proportion.
[0066] Comparative Example 2
[0067] The preparation method was the same as that of Comparative Example 1, except that the entire reaction was carried out by feeding the material onto the liquid surface, while other operations remained unchanged, and colloidal silica was obtained.
[0068] The colloidal silica prepared in this comparative example were all spherical particles.
[0069] Comparative Example 3
[0070] After mixing 165g of ethanol, 6g of ammonia, malic acid (containing 500ppm in the mother liquor) and 27g of water evenly, the mixture was preheated at 25°C to obtain mother liquor A.
[0071] A mixture of 19.19 g tetramethoxysilane and 5.1 g ethanol was added dropwise to mother liquor A using a peristaltic pump. A shower-shaped feed redistributor was used, with 10 holes of 1 mm diameter each, but the feed tube was always positioned above the liquid surface. The dropping rate was 4.5 ml / min, and the stirring speed was 400 r / min. After the dropping was completed, a seed solution was obtained.
[0072] Add 5g of ammonia and 54g of water to the seed crystal solution. At 75℃ and 360r / min, add a mixture of 155g of tetramethoxysilane and 155g of ethanol dropwise to the seed crystal solution at a feed rate of 2ml / min. The feed position is always above the liquid surface. After the dropwise addition is completed, the initial silica sol is obtained.
[0073] Solvent displacement and concentration were performed at a constant liquid level of 101 kPa and 130 °C. Water was added to the system while concentration and displacement were carried out until the methanol content was less than 100 ppm, the solid content was greater than 20 wt%, and the pH was 7.3. Then, the system was filtered through 1 μm and 0.3 μm PFA filter cartridges in a two-stage process to remove large particles, yielding colloidal silica. The resulting silica sol particles exhibited a non-uniform size distribution.
[0074] Table 2 lists the primary particle size, secondary particle size, and particle association degree of the silica particles prepared in each embodiment. As can be seen from the table, the present invention can control the primary particle size in the range of 10-50 nm and the secondary particle size in the range of 20-150 nm, and the final particle association degree is greater than 2, thus achieving the purpose of controllable particle size and morphology.
[0075] Table 1. Particle size (nm) of monomers in various silica sols.
[0076] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Primary particle size (nm) 25 10 32 50 35 36 30 Secondary particle size (nm) 60 35 90 135 50 -- 38 Associativity 2.4 3.5 2.81 2.7 1.42 -- 1.26
[0077] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing non-spherical colloidal silica, comprising the following steps: 1) Mother liquor preparation: Mix organic solvent, alkaline catalyst, acid catalyst and water evenly; 2) Preparation of solution B: Mix alkoxysilane with an organic solvent and stir for a period of time; 3) Particle nucleation: Using a peristaltic pump, the feed redistributor is inserted into the mother liquor, and solution B is added to the mother liquor to carry out the silica particle nucleation reaction to obtain a seed solution; 4) Particle regrowth: Add water and alkaline catalyst to the seed solution obtained in step 3) and stir until homogeneous; continue to add a mixture of alkoxysilane and organic solvent dropwise using a feed redistributor, and carry out particle regrowth under stirring; 5) Concentration and filtration: The sample is heated and concentrated to remove the organic solvent, and then filtered to remove large particles.
2. The preparation method according to claim 1, characterized in that, The mother liquor in step 1) has an organic solvent mass fraction of 65%-85%, a water mass fraction of 13.5%-32%, an alkaline catalyst mass fraction of 1%-3%, and an acid catalyst mass fraction of 10-1000 ppm; and / or, the mass ratio of solution B in step 2) to the mother liquor in step 1) is 1:9 to 1:
5.
3. The preparation method according to claim 1 or 2, characterized in that, The organic solvents mentioned in steps 1) and 2) are selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether; preferably methanol; and / or, in steps 1) and 4), the alkaline catalysts are selected from one or more of alkali metal hydroxides, ammonia, organic amines, and basic amino acids; preferably, the alkaline catalysts are selected from one or more of potassium hydroxide, sodium hydroxide, triethanolamine, tetramethylamine hydroxide, lysine, and arginine.
4. The preparation method according to any one of claims 1-3, characterized in that, The acid catalyst in step 1) is selected from one or more of citric acid, malic acid, oxalic acid, maleic acid, tartaric acid, glutaric acid, adipic acid, malonic acid, succinic acid, fumaric acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, dimethylbutyric acid, hexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, and lactic acid; malic acid is preferred.
5. The preparation method according to any one of claims 1-4, characterized in that, The alkoxysilane in steps 2) and 4) is selected from one or more of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, preferably tetramethoxysilane; and / or, in step 2), the mass ratio of alkoxysilane to organic solvent in the mixture of alkoxysilane and organic solvent is 5:1 to 1:5; in step 4), the mass ratio of alkoxysilane to organic solvent in the mixture of alkoxysilane and organic solvent is 3:1 to 1:3, preferably 3:1 to 1:
1.
6. The preparation method according to any one of claims 1-5, characterized in that, In step 4), the amount of alkoxysilane added is 8-25 times that in step 2); and / or, in step 4), the amount of base catalyst added is 0.1-2 wt% of the seed solution obtained in step 3), and the molar ratio of water added to alkoxysilane added in step 4) is 2-5:
1.
7. The preparation method according to any one of claims 1-6, characterized in that, The feed redistributor mentioned in steps 3) and 4) is any one of the following: shower head, porous tube, coil, or pagoda shape; preferably, the diameter of a single hole is 0.1-10 mm, the number of holes is 3-100, the linear velocity of the flow rate in a single hole is 0.001-1 m / s, and the hole spacing is less than 3 cm.
8. The preparation method according to any one of claims 1-7, characterized in that, The feed rates for steps 3) and 4) are 4.5-14.2 ml / min and 1.25-8 ml / min, respectively; and / or, the bottom of the feed redistributor described in steps 3) and 4) extends below the liquid surface to a depth of 5%-80% of the total height of the liquid surface in the entire system (measured from the bottom of the liquid surface).
9. The preparation method according to any one of claims 1-8, characterized in that, The particle nucleation reaction in step 3) is carried out at a temperature of 25-95℃; and / or the particle regrowth in step 4) is carried out at a temperature of 25-100℃, preferably 60-90℃, and a stirring speed of 200-1000 r / min, preferably 400-600 r / min.
10. The preparation method according to any one of claims 1-9, characterized in that, In step 5), the sample is preferably concentrated by constant liquid level heating solvent replacement and concentration, with a temperature of 50-150℃, preferably 90-130℃, and a pressure of 20-101Kpa.