A method for inducing self-assembly to prepare non-spherical nano-silica particles, a silica sol and applications thereof

Abstract

The application discloses a method for preparing non-spherical nano-silica particles by self-assembly induction, which comprises synthesis of silica particle seeds and further growth of the seeds: by preparing monodispersed seed particles, trace amounts of amphoteric electrolytes are added into the seed growth solution to induce anisotropic growth of the seeds, the types and proportions of the electrolytes are adjusted to make the monodispersed seeds generate silica sol of non-spherical silica particles with different morphologies, and then a series of post-treatments such as water replacement solvent, filtration and concentration are conducted to obtain non-spherical ultra-high-purity silica sol with a mass fraction of more than 18%, a primary particle size of 40-80 nm and a morphology of peanut-shaped, short-chain-shaped and long-chain-shaped, etc. The application also relates to the non-spherical ultra-high-purity silica sol and application thereof in CMP. The preparation method of the application adopts a self-assembly mode of monodispersed seeds to prepare non-spherical particles, and the particle morphology can be further adjusted by adjusting the dosage or types of the self-assembly induction agent.

Description

Technical Field

[0001] This invention belongs to the field of silica nanomaterial preparation, specifically relating to a method for preparing non-spherical nano-silica particles by inducing self-assembly, the product, and its application in semiconductor CMP polishing. Background Technology

[0002] With the ever-increasing performance demands of electronic products, the integration density of integrated circuits has also improved, entering the nanometer era. Simultaneously, higher requirements have been placed on electronic chip manufacturing processes. Metal contamination, organic contamination, and surface quality on silicon wafer surfaces severely affect the yield and performance of precision components, posing new challenges to wafer surface processing. Chemical mechanical polishing (CMP) is the only technology capable of achieving global planarization. One of its most important consumables, the polishing slurry, is primarily composed of high-purity silica sol. Traditional silica sol uses fumed silica particles, which offer the advantage of high polishing speed but are prone to causing scratches on the wafer surface. To address this issue, non-spherical silica abrasives have gradually replaced fumed silica particles, offering the advantage of both high polishing speed and low defect rate.

[0003] Currently, there are methods for preparing non-spherical silica particles, such as template method, block copolymer induction method, and metal salt solution induction method. However, these methods are usually based on adding surfactants, macromolecular polymers, metal salt solutions, etc. to the system. The introduced substances are difficult to remove during the post-processing, which will have a negative impact on the polishing rate; or the removal cost is high and not suitable for large-scale industrial production. Summary of the Invention

[0004] To address the aforementioned problems, this invention innovatively proposes a method for preparing non-spherical ultra-high purity silica sol by self-growth of spherical seeds induced by amphoteric electrolytes. By selecting different types of amphoteric electrolytes or adjusting the concentration of amphoteric electrolytes, silica sols with different particle sizes and different degrees of association can be prepared, with a small scale-up effect and good batch-to-batch stability of particle morphology.

[0005] Another object of the present invention is to provide such a silica sol.

[0006] Another object of the present invention is to provide applications of this silica sol.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A method for preparing non-spherical nano-silica particles by inducing self-assembly includes the following steps:

[0009] 1) Preparation of catalyst solution: Mix organic solvent, ultrapure water and alkaline catalyst evenly in proportion;

[0010] 2) Preparation of seed silicon source solution: Mix the organic solvent and alkoxysilane evenly;

[0011] 3) Prepare the self-assembly induction solution: Mix part of the catalyst solution prepared in step 1) and the amphoteric electrolyte inducer in a certain proportion;

[0012] 4) Preparation of monodisperse silica sol seed crystals: A portion of the seed silicon source solution prepared in step 2) is added dropwise to a portion of the catalyst solution prepared in step 1), and the mixture is stirred to react, thereby obtaining a monodisperse silica sol seed crystal solution; preferably, the mass ratio of the seed silicon source solution to the catalyst solution used in the calcium step is 1:15 to 1:25;

[0013] 5) Amphoteric electrolyte-induced self-assembly of monodisperse seed crystals: The self-assembly induction solution prepared in step 3) is poured into the monodisperse silica sol seed crystal solution prepared in step 4) and mixed evenly for 2-4 hours; then the remaining seed silicon source solution is added dropwise to the monodisperse silica sol seed crystal solution and stirred to react, resulting in silica sol containing non-spherical particles; preferably, the mass ratio of the self-assembly induction solution to the monodisperse silica sol seed crystal solution poured in this step is 0.9:1 to 1.1:1; the mass ratio of the remaining seed silicon source solution to the poured self-assembly induction solution is 2:15 to 2:25;

[0014] 6) Post-treatment of silica sol: The methanol in the concentrated silica sol is replaced with ultrapure water through solvent replacement, concentration and filtration, and then concentrated and filtered to a mass fraction of 20% or higher.

[0015] In one specific embodiment, the organic solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether, preferably methanol; preferably, the mass ratio of the organic solvent to ultrapure water in the catalyst solution of step 1) is 2:1 to 2.5:1.

[0016] In one specific embodiment, the alkaline catalyst is selected from alkali metal hydroxides, ammonia, or organic amines, preferably ammonia; preferably, the alkali metal hydroxide is selected from potassium hydroxide or sodium hydroxide; the organic amine is selected from any one of ethylenediamine, triethanolamine, tetramethylamine hydroxide, and guanidine compounds; more preferably, the guanidine compound is selected from one or more of tetramethylguanidine, trimethylguanidine, and guanidine carbonate; even more preferably, the mass concentration of the alkaline catalyst in the catalyst solution of step 1) is 3% to 5%.

[0017] In one specific implementation, the alkoxysilane is selected from one or more of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, preferably tetramethoxysilane; preferably, the mass ratio of the organic solvent to the alkoxysilane in step 2) is 2:1 to 5:1.

[0018] In one specific embodiment, the amphoteric electrolyte inducer is selected from amino acids or polyampholytes; preferably, the amino acid is selected from any one of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, L-lysine, L-arginine, L-histidine, selenocysteine, or pyrrolidone; the polyampholyte is selected from any one of polysulfonated betaine methacrylate (PSBMA), polycarboxylate betaine methacrylate (PCBMA), polyphosphate betaine methacrylate (PPBMA), or polycarboxylate betaine methacrylamide (PCBAA); more preferably, the amphoteric electrolyte inducer is selected from any one of L-arginine, L-lysine, or L-histidine.

[0019] In one specific implementation, the mass ratio of the catalyst solution used in the self-assembly induction solution prepared in step 3) to the monodisperse silica sol seed solution prepared in step 4) is 0.9:1 to 1.1:1; the mass concentration of the amphoteric electrolyte inducer is 2-110 ppm, based on the total mass of the self-assembly induction solution.

[0020] In one specific implementation, the prepared catalyst solution, seed silicon source solution, and self-assembly induction solution are placed in a water bath and kept at 5-50°C, preferably 30°C; preferably, the preparation process in steps 4) and 5) maintains a constant temperature of 5-50°C, preferably 30°C.

[0021] In one specific implementation, the stirring speed in steps 4) and 5) is 200 r / min to 1000 r / min, preferably 350 r / min; preferably, the dropping speed is 0.1 g / s to 1 g / s, preferably 0.9 g / s.

[0022] On the other hand, a non-spherical nano-silica sol prepared by the aforementioned method.

[0023] On another front, there is the application of the aforementioned non-spherical nano-silica sol in the field of semiconductor CMP polishing.

[0024] Compared with the prior art, the beneficial effects of the present invention include:

[0025] 1) This invention creatively proposes for the first time the preparation of non-spherical silica particles by inducing the self-assembly of spherical seed crystals using an amphoteric electrolyte. The morphology of the self-assembled non-spherical silica particles can be adjusted by changing the size of the spherical seed crystals, and by selecting different types of amphoteric electrolytes or changing the amount of amphoteric electrolyte. The silica sol of this invention has high storage stability and is not prone to agglomeration and sedimentation. The preparation method is simple, and the control of particle size, particle size distribution, and particle morphology is straightforward. Different morphologies of silica sol can be used depending on the polishing rate required for different processes.

[0026] 2) The raw materials used in the preparation method of the present invention are all of high purity, so the prepared silica sol has high purity and few metal impurities and organic residues.

[0027] 3) This invention uses amphoteric electrolytes as self-assembly inducers, which require very little dosage and are highly efficient. Furthermore, their amphoteric and acidic properties allow them to simultaneously serve as pH buffers to stabilize the reaction system.

[0028] 4) Compared with the process of preparing non-spherical silica particles by adding surfactants, macromolecular polymers and metal salt solutions, the preparation method of the present invention can achieve a large proportion of particles with the target morphology by precisely controlling the process conditions, thereby achieving batch-to-batch stability. Attached Figure Description

[0029] Figure 1 These are TEM images of the silica sol particles prepared in Examples 1-5 and Comparative Example 1 of the present invention. Detailed Implementation

[0030] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0031] A method for preparing self-assembled non-spherical nano-silica particles includes the following steps:

[0032] (1) Preparation of catalyst solution: Mix organic solvent, ultrapure water and alkaline catalyst in a certain proportion.

[0033] The organic solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether, preferably methanol. The alkaline catalyst is selected from alkali metal hydroxides, ammonia, or organic amines, preferably ammonia; preferably, the alkali metal hydroxide is selected from potassium hydroxide or sodium hydroxide; the organic amine is selected from any one of ethylenediamine, triethanolamine, tetramethylamine hydroxide, and guanidine compounds; more preferably, the guanidine compound is selected from one or more of tetramethylguanidine, trimethylguanidine, and guanidine carbonate.

[0034] In this step, the mass ratio of organic solvent to ultrapure water is 2:1 to 2.5:1, for example, including but not limited to 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, and 2.5:1. Specifically, in the preparation process, the organic solvent and ultrapure water can be prepared in the specified ratio first, and then a certain amount of alkaline catalyst can be added to obtain a catalyst solution. The mass concentration of the alkaline catalyst in the entire catalyst solution is 3% to 5%, for example, 3%, 3.5%, 4%, 4.5%, and 5%.

[0035] (2) Prepare the seed silicon source solution: Mix the organic solvent and alkoxysilane evenly.

[0036] The organic solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether, preferably methanol, and more preferably the same organic solvent used in step (1). The alkoxysilane is one or more of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane, preferably tetramethoxysilane.

[0037] In this step, the mass ratio of organic solvent to alkoxysilane is 2:1 to 5:1, for example, including but not limited to 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, and 5:1.

[0038] (3) Preparation of self-assembly induction solution: Mix organic solvent, ultrapure water, alkaline catalyst and amphoteric electrolyte in a certain proportion.

[0039] The alkaline catalyst is selected from alkali metal hydroxides, ammonia, or organic amines, preferably ammonia; more preferably, the alkali metal hydroxide is selected from potassium hydroxide or sodium hydroxide; the organic amine is selected from any one of ethylenediamine, triethanolamine, tetramethylamine hydroxide, and guanidine compounds; more preferably, the guanidine compound is selected from one or more of tetramethylguanidine, trimethylguanidine, and guanidine carbonate; preferably, the alkaline catalyst is the same as the alkaline catalyst in step 1). The organic solvent is also the same as the organic solvent in step 1), and the mass ratio of the organic solvent, ultrapure water, and alkaline catalyst is exactly the same as the mass ratio in step 1); that is, the catalyst solution prepared in step 1) can be directly used to prepare the self-assembly induction solution in step 3), that is, take a portion of the catalyst solution prepared in step 1), add a certain amount of amphoteric electrolyte inducing agent to it, and the self-assembly induction solution is prepared.

[0040] The amphoteric electrolyte inducer is an amino acid such as glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, L-lysine, L-arginine, L-histidine, selenocysteine, and pyrrolidone, or a polyampholyte such as polysulfonated betaine methacrylate (PSBMA), polycarboxylated betaine methacrylate (PCBMA), polyphosphobetaine methacrylate (PPBMA), and polycarboxylated betaine methacrylamide (PCBAA), preferably L-arginine, L-lysine, and L-histidine.

[0041] In the self-assembly induction solution prepared in this step, the mass ratio of the catalyst solution prepared in step 1) to the monodisperse silica sol seed solution prepared in step 4) is 0.9:1 to 1.1:1, for example, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, etc.; the concentration of the amphoteric electrolyte inducer added to this part of the catalyst solution is 2-110 ppm, for example, including but not limited to 2 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 105 ppm, 110 ppm, based on the total mass of the self-assembly induction solution.

[0042] (4) Preparation of monodisperse silica sol seed crystals: At a specific temperature, a portion of the seed silicon source solution prepared in step 2) is added to a portion of the catalyst solution prepared in step 1) at a specific rate, and the mixture is stirred and reacted for a period of time to obtain monodisperse silica sol seed crystals. The mass ratio of the portion of seed silicon source solution to the portion of catalyst solution is 1:15 to 1:25, for example, mass ratios of 1:15, 1:15.5, 1:16, 1:16.5, 1:17, 1:17.5, 1:18, 1:18.5, 1:19, 1:19.5, 1:20, 1:20.5, 1:21, 1:22, 1:23, 1:24, 1:25, etc.

[0043] The reaction temperature during this preparation step is between 5-50℃, including but not limited to 5℃, 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, and 50℃, preferably 30℃. The dropping rate of the seed silicon source solution into the catalyst solution is 0.1g / s-1g / s, including but not limited to 0.1g / s, 0.2g / s, 0.3g / s, 0.4g / s, 0.5g / s, 0.6g / s, 0.7g / s, 0.8g / s, 0.9g / s, and 1.0g / s, preferably 0.9g / s. Preferably, the catalyst solution, seed silicon source solution, and self-assembly induction solution prepared in the aforementioned steps are also placed in a water bath and kept at 5-50℃, preferably 30℃.

[0044] During this preparation step, the stirring speed is 200 r / min-1000 r / min, including but not limited to 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, and 1000 r / min, and the stirring reaction time is 0.5 h-3 h, including but not limited to 1 h, 1.5 h, 2 h, 2.5 h, and 3 h.

[0045] (5) Amphoteric electrolyte-induced self-assembly of monodisperse seed crystals: The prepared self-assembly induction solution is poured into the monodisperse seed crystal solution prepared in the previous step and mixed evenly. The mass ratio of the two is 0.9:1 to 1.1:1, and the mixture is kept for 2-4 hours. Then, the remaining seed silicon source solution is added dropwise to the aforementioned monodisperse seed crystal solution at a specific rate, and the mixture is stirred and reacted for a period of time to obtain silica sol containing non-spherical particles. The mass ratio of the remaining seed silicon source solution to the self-assembly induction solution is 2:15 to 2:25, for example, including but not limited to 2:15, 2:16, 2:17, 2:18, 2:19, 2:20, 2:21, 2:22, 2:23, 2:24, and 2:25.

[0046] The remaining seed silicon source solution is added to the monodisperse seed solution at a rate consistent with the drop rate in the monodisperse silica sol seed preparation step, for example, 0.1 g / s-1 g / s. The stirring speed is 200 r / min-1000 r / min, including but not limited to 200 r / min, 300 r / min, 400 r / min, 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min, and 1000 r / min. The stirring reaction time is 0.5 h-3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, and 3 h.

[0047] (6) Post-treatment of silica sol: The methanol in the concentrated silica sol is replaced with ultrapure water by solvent replacement, concentration and filtration, and then concentrated and filtered to a mass fraction of 20% or more.

[0048] In this invention, the post-processing of the silica sol can refer to existing technologies, such as patent CN102390838A. Specifically, the silica sol is concentrated by reduced pressure heating at 10 kPa and 100°C to approximately 20%. Then, ultrapure water is added while evaporating the organic solvent until an ultra-high purity silica sol with a mass concentration of 20% is obtained.

[0049] 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.

[0050] The main raw materials used in the following examples and comparative examples are shown in Table 1:

[0051]

[0052] Detection method:

[0053] The test method for solid content is based on HGT 2521-2008 Industrial Silica Sol.

[0054] The degree of association of silica sol particles was measured using a Malvern particle size analyzer Zetasizer Nano ZS90 to determine the secondary particle size.

[0055] The surface morphology of the silica sol was characterized by TEM.

[0056] Each embodiment and comparative example was carried out according to the main process conditions in Table 2:

[0057] Example 1

[0058] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g catalyst solution and 0.038g L-arginine. 9g of the seed silicon source solution was added to the remaining 177g catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.06 was obtained.

[0059] Example 2

[0060] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g catalyst solution and 0.95g L-arginine. 9g of the seed silicon source solution was added to the remaining 177g catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.12 was obtained.

[0061] Example 3

[0062] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g catalyst solution and 1.9g L-arginine. 9g of the seed silicon source solution was added to the remaining 177g catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.18 was obtained.

[0063] Example 4

[0064] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g catalyst solution and 0.95g L-lysine. 9g of the seed silicon source solution was added to the remaining 177g catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.15 was obtained.

[0065] Example 5

[0066] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g catalyst solution and 0.95g L-histidine. 9g of the seed silicon source solution was added to the remaining 177g catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.07 was obtained.

[0067] Example 6

[0068] A catalyst solution was prepared by mixing 256.1 g of ethyl propyl ether, 128.1 g of water, and 20.3 g of ethylenediamine. A seed silicon source solution was prepared by mixing 16.4 g of ethyl propyl ether with 8.2 g of tetraethoxysilane (TEOS). A self-assembly induction solution was prepared by mixing 215 g of the catalyst solution with 0.5 g of self-polysulfonate betaine methacrylate. 7.5 g of the seed silicon source solution was added to the remaining 189.5 g of the catalyst solution using a peristaltic pump, with the addition completed within 80 seconds. The reaction was carried out at 45 °C and 550 r / min for 2 hours to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 17.1 g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 182 seconds. The reaction was continued for 2 hours while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10 kPa and 100 °C to approximately 20%, yielding the concentrated silica sol. Then, while adding ultrapure water, the mixture is evaporated until a silica sol with a mass concentration of 20% and an association degree of 0.12 is obtained.

[0069] Example 7

[0070] A catalyst solution was prepared by mixing 234.3 g of isopropanol, 93.7 g of water, and 10.2 g of tetramethylguanidine. A seed silicon source solution was prepared by mixing 28 g of isopropanol with 5.6 g of tetrapropoxysilane (TPOS). A self-assembly induction solution was prepared by mixing 165 g of the catalyst solution with 1.4 g of polycarboxylate betaine methacrylamide. 11.5 g of the seed silicon source solution was added to the remaining 173.2 g of the catalyst solution using a peristaltic pump, with the addition completed within 20 seconds. The reaction was carried out at 10 °C and 950 r / min for 3 hours to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 22.1 g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 40 seconds. The reaction was continued for 3 hours while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10 kPa and 100 °C to approximately 20%, yielding the concentrated silica sol. Then, while adding ultrapure water, the mixture is evaporated until a silica sol with a mass concentration of 20% and an association degree of 0.16 is obtained.

[0071] Comparative Example 1

[0072] A catalyst solution was prepared by mixing 240g methanol, 100g water, and 14g ammonia. A seed silicon source solution was prepared by mixing 20g methanol and 7g tetramethoxysilane (TMOS). A self-assembly induction solution was prepared by mixing 177g of the catalyst solution. 9g of the seed silicon source solution was added to the catalyst solution using a peristaltic pump, with the addition completed within 10 seconds. The reaction was carried out at 30℃ and 350r / min for 1 hour to obtain the seed solution. Then, the self-assembly induction solution was added to the reaction system, and after reacting for 2 hours, the remaining 18g of the seed silicon source solution was added to the reaction system using a peristaltic pump, with the addition completed within 20 seconds. The reaction was continued for 1 hour while maintaining the same speed and temperature. The solution was then concentrated under reduced pressure at 10KPa and 100℃ to approximately 20%, yielding a concentrated silica sol. Ultrapure water was then added while evaporation continued until a silica sol with a mass concentration of 20% and an association degree of 0.01 was obtained.

[0073] Table 2 shows the amount and ratio of solvent in each embodiment and the comparative embodiment.

[0074]

[0075] In the examples, by controlling the type and content of different amphoteric electrolytes, silica sols with an association degree of 0.06–0.18 and a morphology of non-spherical particles could be prepared. Figure 1 TEM images of Examples 1-5 and Comparative Example 1 are shown. By comparing Examples 1-3 and Comparative Example 1, the effect of adjusting the content of amphoteric electrolytes in the self-assembly induction solution on particle morphology was investigated. In Comparative Example 1, under preparation conditions without amphoteric electrolytes, the particles were monodisperse spherical. In Examples 1-5, the addition of amphoteric electrolytes as self-assembly inducers resulted in non-spherical particles. TEM images of Examples 1-3 show that adding different amounts of the same type of amphoteric electrolyte during preparation affected the particle association degree. As the amphoteric electrolyte content increased, the particles gradually changed from a peanut-like shape to a short-chain or even long-chain shape. Examples 2, 4, and 5, which used different types of amphoteric electrolytes in the same amount as self-assembly inducers during preparation, also affected the degree of particle self-assembly, thus influencing the morphology.

[0076] Although the present invention has been described in detail through the preferred embodiments described above, it should be understood that the above description should not be considered as a limitation of the present invention. Those skilled in the art will understand that modifications or adjustments can be made to the present invention based on the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing non-spherical nano-silica particles by inducing self-assembly, characterized in that, Includes the following steps: 1) Preparation of catalyst solution: Mix organic solvent, ultrapure water and alkaline catalyst evenly in proportion; 2) Preparation of seed silicon source solution: Mix the organic solvent and alkoxysilane evenly; 3) Preparation of self-assembly induction solution: Mix part of the catalyst solution prepared in step 1) and the amphoteric electrolyte inducer in a certain proportion; 4) Preparation of monodisperse silica sol seed crystals: A portion of the seed silicon source solution prepared in step 2) is added dropwise to a portion of the catalyst solution prepared in step 1), and the mixture is stirred to react, thereby obtaining a monodisperse silica sol seed crystal solution; 5) Amphoteric electrolyte-induced monodisperse seed crystal self-assembly: Pour the self-assembly induction solution prepared in step 3) into the monodisperse silica sol seed crystal solution in step 4) and mix evenly, keep for 2-4 hours; then add the remaining seed silicon source solution dropwise into the monodisperse silica sol seed crystal solution and stir to react, to obtain silica sol containing non-spherical particles. 6) Post-treatment of silica sol: The methanol in the concentrated silica sol is replaced with ultrapure water through solvent replacement, concentration and filtration, and then concentrated and filtered to a mass fraction of 20% or higher. The amphoteric electrolyte inducer is selected from amino acids or polyampholytes; the amino acids are selected from any one of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, L-lysine, L-arginine, L-histidine, selenocysteine, or pyrrolidone; the polyampholytes are selected from any one of polysulfonated betaine methacrylate (PSBMA), polycarboxylate betaine methacrylate (PCBMA), polyphosphate betaine methacrylate (PPBMA), and polycarboxylate betaine methacrylamide (PCBAA). The mass concentration of the amphoteric electrolyte inducer is 2-110 ppm, based on the total mass of the self-assembly induction solution.

2. The method according to claim 1, characterized in that, The mass ratio of the seed silicon source solution to the catalyst solution used in step 4) is 1:15 to 1:

25.

3. The method according to claim 1, characterized in that, In step 5), the mass ratio of the self-assembly induction solution to the monodisperse silica sol seed solution is 0.9:1 to 1.1:1; the mass ratio of the remaining seed silicon source solution to the self-assembly induction solution is 2:15 to 2:

25.

4. The method according to claim 1, characterized in that, The organic solvent is selected from one or more of methanol, ethanol, propanol, isopropanol, acetonitrile, acetone, methyl ethyl ketone, diethyl ether, and ethyl propyl ether.

5. The method according to claim 4, characterized in that, The organic solvent is methanol.

6. The method according to claim 4, characterized in that, The mass ratio of the organic solvent to ultrapure water in the catalyst solution of step 1) is 2:1 to 2.5:

1.

7. The method according to claim 1, characterized in that, The alkaline catalyst is selected from alkali metal hydroxides, ammonia, or organic amines.

8. The method according to claim 7, characterized in that, The alkaline catalyst is selected from ammonia water.

9. The method according to claim 7, characterized in that, The alkali metal hydroxide is selected from potassium hydroxide or sodium hydroxide; the organic amine is selected from any one of ethylenediamine, triethanolamine, tetramethylamine hydroxide, and guanidine compounds.

10. The method according to claim 9, characterized in that, The guanidine compounds are selected from one or more of tetramethylguanidine, trimethylguanidine, and guanidine carbonate.

11. The method according to claim 10, characterized in that, The mass concentration of the alkaline catalyst in the catalyst solution of step 1) is 3% to 5%.

12. The method according to claim 1, characterized in that, The alkoxysilane is selected from one or more of tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane.

13. The method according to claim 12, characterized in that, The alkoxysilane mentioned is tetramethoxysilane.

14. The method according to claim 12, characterized in that, The mass ratio of the organic solvent to the alkoxysilane in step 2) is 2:1 to 5:

1.

15. The method according to claim 1, characterized in that, The amphoteric electrolyte inducer is selected from any one of L-arginine, L-lysine, or L-histidine.

16. The method according to claim 1, characterized in that, The mass ratio of the catalyst solution used in the self-assembly induction solution prepared in step 3) to the monodisperse silica sol seed solution prepared in step 4) is 0.9:1 to 1.1:

1.

17. The method according to claim 1, characterized in that, The prepared catalyst solution, seed silicon source solution, and self-assembly induction solution are placed in a water bath and kept at 5-50℃.

18. The method according to claim 17, characterized in that, The prepared catalyst solution, seed silicon source solution, and self-assembly induction solution are placed in a water bath and kept at 30°C.

19. The method according to claim 17, characterized in that, In steps 4) and 5), the preparation process is carried out at a constant temperature of 5-50℃.

20. The method according to claim 19, characterized in that, The preparation process in steps 4) and 5) is carried out at a constant temperature of 30°C.

21. The method according to claim 1, characterized in that, In steps 4) and 5), the stirring speed is 200 r / min-1000 r / min, and the stirring reaction time is 0.5 h-3 h.

22. The method according to claim 21, characterized in that, The stirring speed in steps 4) and 5) is 350 r / min.

23. The method according to claim 21, characterized in that, The dropping rate is 0.1 g / s - 1 g / s.

24. The method according to claim 23, characterized in that, The dropping rate is 0.9 g / s.

25. A non-spherical nano-silica sol prepared by the method according to any one of claims 1 to 24.

26. The application of the non-spherical nano-silica sol of claim 25 in the field of semiconductor CMP polishing.

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