Anisometric nanosilica sol, its preparation method and use

Abstract

The application discloses a special-shaped nano silicon sol and a preparation method and application thereof. An organic silicon source is used as raw material, water and alcohol are used as mixed agents, and an initial silicon sol is generated under the action of an alkaline catalyst, and then a nutrient solution is reacted with the initial silicon sol, and after aging, the special-shaped nano silicon sol is obtained. The polishing liquid prepared from the special-shaped silicon sol can be used for polishing in chip field related processes, and has excellent removal rate. The nano silicon sol particles prepared by the method are special-shaped / non-spherical, the true density of the particles is 1.8-2.2 g / cm 3 , the experimental steps are simple, the silicon sol has high purity, and large-scale industrial amplification and industrialization are facilitated.

Description

Technical Field

[0001] This application relates to an irregularly shaped nano-silica sol, its preparation method, and its application, belonging to the field of materials preparation. Background Technology

[0002] Nano-silica sol has a wide range of applications in many fields such as mechanical casting, biomedicine, civil engineering, new energy, aerospace, and semiconductor microelectronics.

[0003] There is currently a great deal of research on the preparation of irregularly shaped nano-silica sols. Chinese patent 108862291A discloses a method for preparing sea urchin-shaped nano-silica sols, which is based on… The method has been improved, but the preparation process requires a large amount of ethanol, which will significantly increase the energy consumption of later processing. Domestic patent CN107010631A discloses a method for preparing non-spherical colloidal silica nanoparticles, which uses water glass as a raw material, containing a large amount of metal impurities, and cannot meet the high purity requirements of semiconductor CMP. Patent US8529787B2 discloses a method for preparing dendritic nano-silica, which adds hydrolyzed organosilane to an alkaline catalyst and obtains non-spherical particles through long-term dropwise addition. This method solves the product purity problem by using organosilane as a raw material, but it is time-consuming, complex, and difficult to control experimental conditions. International patent US005221497A proposes using water glass hydrolysate with added Ca or Mg ions and then mixing it with an alkaline catalyst, reacting the mixture at high temperature to obtain elongated nano-silica sol. Although the operation is simple, metal ions are introduced into the experimental operation, and the metal impurity content of the product is not controlled.

[0004] The main methods for preparing nano-silica include gas-phase method, chemical precipitation method, sol-gel method, and so on. Methods, etc. For silica sols used in semiconductor chemical mechanical polishing, high purity is required, particle morphology is diverse, and particle size distribution is uniform, making preparation difficult and mass production challenging. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of the existing technology, this invention provides a simple and efficient method for preparing nano-silica. The microchannel mixer used in this invention precisely controls the reaction process in terms of both mass and heat transfer, making the entire operation more stable and uniform. The whole process is simple to operate, convenient for post-processing, has high production efficiency, and is easy to scale up industrially.

[0006] According to one aspect of this application, an irregularly shaped nano-silica sol is provided, wherein the nano-silica particles in the irregularly shaped nano-silica sol have a non-spherical irregular morphology;

[0007] The average particle size of the irregularly shaped nano-silica sol is 20–200 nm.

[0008] The PDI of the irregularly shaped nano-silica sol is 0.1 to 0.4;

[0009] The true density of the irregularly shaped nano-silica sol is 1.8–2.2 g / cm³. 3 .

[0010] According to another aspect of this application, a method for preparing the above-mentioned irregularly shaped nano-silica sol is provided, comprising the following steps:

[0011] A water-alcohol solution containing an organosilicon source is mixed with an alkaline catalyst under an inactive gas atmosphere, heated (I), and aged (I) to obtain seed crystals. The seed crystals are then mixed with a nutrient solution in a microchannel mixer, heated (II), and aged (II) to obtain the irregularly shaped nano-silica sol.

[0012] The organosilicon source has a carbon content ≥4 and an oxygen number ≥1. During the reaction, the organosilicon source undergoes hydrolysis and condensation to form Si-O-Si bonds, which also include other carbon chains. This structure alters the density of the nanoparticles. Ultimately, the true density of the particles is changed by adjusting the stoichiometry of the organosilicon source. The source is selected from at least one of the following: methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, N-aminoethylγ-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, β-(3,4)epoxycyclohexylethyltrimethoxysilane, 1,2-bistrimethoxysilylethane, methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0013] In the aqueous alcohol solution, the alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol; the added alcohol should be as consistent as possible with the solubility of the organosilicon source. Methanol and ethanol are preferred.

[0014] The alkaline catalyst is selected from at least one of potassium hydroxide, potassium carbonate, ammonia, urea, ethanolamine, ethylenediamine, diethanolamine, triethanolamine, ammonium citrate, tetramethylammonium hydroxide, basic amino acids, and nitrogen-containing organic bases.

[0015] In the aqueous alcoholic solution containing an organosilicon source, the mass content of the organosilicon source is 1-99%;

[0016] The mass ratio of the alcohol to the organosilicon source is 0–5; adding too much alcohol will significantly increase post-processing costs. For some organosilicon sources that are highly susceptible to hydrolysis, the amount of alcohol added can also be 0.

[0017] The pH of the alkaline catalyst is controlled between 8 and 13, preferably between 9 and 12.

[0018] The inactive gas atmosphere is selected from at least one of nitrogen, argon, and helium.

[0019] The temperature of heating element I is 50–200°C;

[0020] Optionally, the temperature of heating I is 70–100°C;

[0021] If the reaction temperature is below 50℃, the chemical equilibrium of the reaction will not be reached and the reaction will be incomplete; if it is above the predetermined temperature, the energy consumption will be too high and the economy will be poor.

[0022] The heating time for I is 0.5 to 10 hours;

[0023] The aging temperature for step I is 70–100°C;

[0024] The aging time for the first stage is 0.01 to 5 hours.

[0025] Optionally, the aging time for the first aging process is 0.1 to 1 hour.

[0026] The microchannel mixer is cross-shaped, T-shaped, or Y-shaped;

[0027] The inner diameter of the microchannel mixer is 0.1–6 mm;

[0028] The effective mixing length inside the microchannel mixer is 1–50 cm.

[0029] An inner diameter less than 0.1 mm can easily cause channel blockage; an inner diameter greater than 6 mm will result in laminar flow, making it impossible to achieve the purpose of mixing. An inner diameter range of 0.1–6 mm can generate turbulent flow in the mixture within the channel, increasing heat and mass transfer efficiency.

[0030] The nutrient solution is obtained by mixing a silicon-containing compound with a solvent and then hydrolyzing the mixture.

[0031] The silicon-containing compound is selected from at least one of water glass, lithium silicate, sodium silicate, potassium silicate, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, N-aminoethylγ-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, β-(3,4)epoxycyclohexylethyltrimethoxysilane, 1,2-bistrimethoxysilylethane, methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0032] The solvent is water;

[0033] Preferably, the solvent contains alcohols;

[0034] The alcohol is selected from at least one of methanol, ethanol, isopropanol, and n-butanol;

[0035] The solid-liquid ratio of the seed crystals to the nutrient solution is 1:99 to 99:1.

[0036] The temperature of heating II is 50–100°C;

[0037] The heating time II is 0.5 to 60 hours;

[0038] The aging temperature for the second stage is 70–100°C;

[0039] The aging time for the second stage is 1 to 24 hours.

[0040] Optionally, the aging time II is 6 to 20 hours.

[0041] According to another aspect of this application, an application of the aforementioned irregularly shaped nano-silica sol is provided for use in a polishing slurry. This polishing slurry exhibits a high removal rate.

[0042] The beneficial effects that this application can produce include:

[0043] (1) By adopting a segmented control method, the problem of operation that is difficult to control due to excessively long process is avoided.

[0044] (2) A microchannel mixer is used and an inert gas is introduced to increase the mixing efficiency, so that the reaction is in a kinetically uniform state at any stage.

[0045] (3) The process is simple to operate and is easier to scale up industrially because the scale-up effect is eliminated. Attached Figure Description

[0046] Figure 1 This is a particle size distribution diagram of the heterogeneous silica sol prepared in Example 1.

[0047] Figure 2 This is a particle size distribution diagram of the heterogeneous silica sol prepared in Example 2.

[0048] Figure 3 This is a SEM image of the spherical silica sol prepared in Comparative Example 1, at a scale of 100 nm.

[0049] Figure 4 This is a SEM image of the heterogeneous silica sol prepared in Example 1, with a scale of 100 nm. Detailed Implementation

[0050] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples, but these embodiments do not constitute a limitation on the present invention. Those skilled in the art can modify the details and form of the technical solutions of the present invention within the scope of the principles of the present invention, but all such modifications fall within the protection scope of the present invention.

[0051] The particle size data in the embodiments of this invention were obtained using Malvern laser particle size analysis. The non-spherical / irregularly shaped silica sol provided by this invention, used as abrasive particles, can be used as a polishing slurry in semiconductor CMP processes, exhibiting a high removal rate for coatings such as single-crystal silicon, TEOS, or W.

[0052] Example 1:

[0053] 3278.56 g of methyl orthosilicate, 35 g of methyltrimethoxysilane, 2790 g of methanol, and 69750 g of deionized water were mixed and stirred until homogeneous to obtain solution A. 30 g of ammonia water and solution A were simultaneously introduced into a microchannel mixer, while N2 gas was introduced into the mixer. The microchannel had an inner diameter of 1 mm and an effective mixing length of 6 cm. The reaction was heated to 55 °C while mixing, and aged for 1 hour to obtain seed crystal C.

[0054] 15g of aminopropyltriethoxysilane, 235.8g of methyl orthosilicate, and 9000g of deionized water were mixed and hydrolyzed to obtain nutrient solution D. 1896g of seed crystals C and nutrient solution D were simultaneously introduced into a microchannel mixer and N2 gas was introduced. The mixture was heated to 95℃ while mixing and the experiment was maintained for 5 hours to obtain non-spherical / irregular silica sol products.

[0055] The particle size of the obtained product was analyzed using a Malvern laser particle size analyzer, with an average particle size of 48.59 nm and a particle density concentration (PDI) value of 0.134. The results are shown in [reference needed]. Figure 1 .

[0056] Figure 4 This is a SEM image of the heterogeneous silica sol prepared in Example 1, at a scale of 100 nm. The image shows that the obtained product has a non-spherical, irregular morphology.

[0057] Example 2:

[0058] 1566g of methyl orthosilicate, 10g of methyltrimethoxysilane, 1235.5g of isopropanol, and 29850g of deionized water were mixed and stirred until homogeneous to obtain solution A. 5g of tetramethylammonium hydroxide was simultaneously introduced into a microchannel mixer along with solution A, while N2 gas was introduced into the mixer. The reaction mixture was heated to 70°C and aged for 0.4h to obtain seed crystal C.

[0059] 114g of methyl orthosilicate, 3000g of deionized water and 15g of methanol were mixed and hydrolyzed to obtain nutrient solution D; 856g of seed crystals C and nutrient solution D were simultaneously introduced into a microchannel mixer and N2 gas was introduced. The mixture was heated to 95℃ while mixing and the experiment was maintained for 5 hours to obtain non-spherical / irregular silica sol products.

[0060] The particle size of the obtained product was analyzed using a Malvern laser particle size analyzer, with an average particle size of 132 nm and a particle density concentration (PDI) value of 0.26. The results are shown in [reference needed]. Figure 2 .

[0061] The morphology of the product was characterized in a similar manner to that of Example 1.

[0062] Comparative Example 1:

[0063] 1566g of tetraethyl orthosilicate and 3560g of ethanol were mixed and stirred until homogeneous to obtain solution A. 10g of ammonia and 2545.2g of deionized water were mixed and heated to 50℃ to prepare solution B. Solution A was added to solution B, and the mixture was kept at 50℃ and aged for 2 hours to obtain spherical silica sol.

[0064] The particle size of the obtained product was analyzed using a Malvern laser particle size analyzer, and the average particle size was 50.5 nm with a concentration density (PDI) value of 0.026.

[0065] Figure 3 This is a SEM image of the spherical silica sol prepared in Comparative Example 1, at a scale of 100 nm. As can be seen from the image, the product has a regular spherical morphology.

[0066] Table 1 shows the physical properties and polishing effects of the silica sol in the examples and comparative examples. The polishing experiment used a Bruker CP-4 polishing machine; the polishing pressure was 3 psi; the polishing time was 2 min; the grinding table speed was 80 rpm; the grinding head speed was 150 rpm; the polishing fluid flow rate was 100 mL / min; and the polishing object was a 4-inch monocrystalline silicon wafer.

[0067] Table 1

[0068]

[0069]

[0070] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing irregularly shaped nano-silica sol, characterized in that, Includes the following steps: A water-alcohol solution containing an organosilicon source is mixed with an alkaline catalyst under an inactive gas atmosphere, heated (I), and aged (I) to obtain seed crystals. The seed crystals are then mixed with a nutrient solution in a microchannel mixer, heated (II), and aged (II) to obtain the irregularly shaped nano-silica sol. The nano-silica particles in the irregularly shaped nano-silica sol have a non-spherical, irregular morphology. The average particle size of the irregularly shaped nano-silica sol is 20~200nm; The PDI of the irregularly shaped nano-silica sol is 0.1~0.4; The true density of the irregularly shaped nano-silica sol is 1.8~2.2 g / cm3; The organosilicon source is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, N-aminoethylγ-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, β-(3,4)epoxycyclohexylethyltrimethoxysilane, 1,2-bistrimethoxysilylethane, methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane.

2. The preparation method according to claim 1, characterized in that: In the aqueous alcohol solution, the alcohol is selected from at least one of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol; The alkaline catalyst is selected from at least one of potassium hydroxide, potassium carbonate, ammonia, urea, ethanolamine, ethylenediamine, diethanolamine, triethanolamine, ammonium citrate, tetramethylammonium hydroxide, and basic amino acids.

3. The preparation method according to claim 1, characterized in that, In the aqueous alcoholic solution containing an organosilicon source, the mass content of the organosilicon source is 1-99%; The mass ratio of the alcohol to the organosilicon source is 0~5; The inactive gas atmosphere is selected from at least one of nitrogen, argon, and helium.

4. The preparation method according to claim 1, characterized in that, The temperature of heating element I is 50~200℃; The heating time for I is 0.5~10h; The aging temperature for step I is 70~100℃; The aging time for the first stage is 0.01 to 5 hours.

5. The preparation method according to claim 1, characterized in that, The microchannel mixer is cross-shaped, T-shaped, or Y-shaped; The inner diameter of the microchannel mixer is 0.1~6 mm; The effective mixing length inside the microchannel mixer is 1~50 cm.

6. The preparation method according to claim 1, characterized in that, The nutrient solution is obtained by mixing a silicon-containing compound with a solvent and then hydrolyzing the mixture. The silicon-containing compound is selected from at least one of water glass, lithium silicate, sodium silicate, potassium silicate, methyltrimethoxysilane, methyltriethoxysilane, tetramethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetraethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, phenyltrimethoxysilane, N-aminoethylγ-aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, β-(3,4)epoxycyclohexylethyltrimethoxysilane, 1,2-bistrimethoxysilylethane, methacryloxypropyltrimethoxysilane, and vinyltrimethoxysilane. The solvent includes water; The solvent contains alcohols.

7. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of the seed crystals to the nutrient solution is 1:99~99:

1.

8. The preparation method according to claim 1, characterized in that, The temperature of heating II is 50~100℃; The heating time II is 0.5~60h; The aging temperature for stage II is 70~100℃; The aging time for the second stage is 1 to 24 hours.

9. An application of the irregularly shaped nano-silica sol according to claim 1, characterized in that, Used in polishing slurries.

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