High-purity silica sol as well as preparation method and application thereof

Abstract

The invention discloses high-purity silica sol as well as a preparation method and application thereof. The polishing solution is mainly used for polishing solution components in a chemical mechanical polishing (CMP) process in semiconductor manufacturing. According to the method, high-purity and high-solid-content silica sol is formed through direct synthesis of organosilane in an aqueous solution. The preparation process comprises the following steps: mixing an alkali solution and organosilane, heating, aging, and evaporating and removing low-boiling-point organic matters. The method avoids the use of a large amount of solvent and the introduction of impurities, improves the purity and consistency of the product, and is suitable for large-scale industrial production. The prepared silica sol has uniform nanoscale particle size (20-150nm) and higher silicon oxide content (more than 20%), and can effectively meet the fine requirement of a CMP (chemical mechanical polishing) process on abrasive particles.

Description

Technical Field

[0001] The present application relates to a high-purity silica sol and a preparation method and application thereof, belonging to the field of fine chemicals. Background Art

[0002] In the semiconductor manufacturing process, multi-layer wiring is often required to accommodate more components on a limited wafer surface. The establishment of a new layer often requires the surface of the previous layer to be polished and ground in advance. Only after global flatness is achieved can the subsequent manufacturing process be carried out. Chemical mechanical polishing (CMP) is the best means to achieve global flatness. It is a process that achieves global flatness through the coupling of chemical reaction and mechanical action. The chemical reaction is mainly the reaction between the reagent in the polishing liquid and the surface of the wafer to form a loose layer, which is then removed by mechanical action; and the mechanical action is mainly the friction between the abrasive particles in the polishing liquid and the wafer, which is used to achieve rapid material removal through friction. Common abrasive particles include silicon oxide, cerium oxide, aluminum oxide, etc. Among them, silicon oxide is widely used in the CMP field due to its moderate hardness, controllable particle size and morphology.

[0003] CN101495409A discloses a method for preparing silica sol, using methanol and water as solvents, ammonia water as a catalyst, and TMOS as a precursor of silicon oxide to prepare silica sol and then add a dispersant to prevent the agglomeration of particles. This method uses a large amount of methanol as a solvent, which adds a burden to the subsequent separation and purification. At the same time, the addition of the dispersant also reduces the purity of the silica sol.

[0004] CN116143129A discloses a method for preparing peanut-shaped silicon oxide. The method hydrolyzes organic silane by acid catalysis, then polymerizes by base catalysis, then induces the formation of non-spherical particles by organic ammonium salt, and finally further adds organic silane. In this method, organic acid needs to be introduced for catalytic hydrolysis, thus further reducing the purity of the silica sol product. In addition, the introduction of organic acid will increase the amount of alkali used in the polymerization process, which is not conducive to the preparation of high-purity silica sol.

[0005] CN102164853A discloses a method for preparing colloidal silica having a curved structure or a branched structure. The method comprises adding a hydrolyzed solution of an organic silane to an alkaline aqueous solution until the pH of the mixed solution is less than 7, then adding an alkaline aqueous solution to make the pH greater than 7, and then adding the hydrolyzed solution of the organic silane while maintaining the pH of the mixed solution at more than 7. In this method, the pH of the mixed solution needs to be precisely regulated, which is difficult to operate. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing high-purity and high-content silica sol. The silica sol prepared by this method has high purity and high silicon oxide content, and is suitable for the chemical mechanical polishing process in the chip manufacturing process. In addition, the silica sol prepared by this method has a small amplification effect and can be suitable for large-scale batch production.

[0007] According to one aspect of the present application, a method for preparing high-purity silica sol is provided, comprising the following steps:

[0008] (1) mixing an organosilane with an alcohol to obtain a mixed solution A and a mixed solution D;

[0009] (2) mixing the alkaline solution with the mixed solution A at 60 to 120° C. to obtain a mixed solution B;

[0010] (3) mixing the low boiling point organic matter, alcohol and alkaline solution to obtain a mixed solution C;

[0011] (4) Adding the mixed solution C and the mixed solution D dropwise into the mixed solution B, stirring, reacting, aging, heating and evaporating, filtering, and concentrating to obtain the high-purity silica sol.

[0012] The organosilane is selected from at least one of tetramethoxysilane and tetraethoxysilane;

[0013] The alcohol is selected from at least one of methanol, ethanol and isopropanol;

[0014] The base is selected from at least one of organic amines, alkali metal hydroxides, ammonia water, and guanidine compounds;

[0015] The pH of the alkaline solution is 7.5 to 12.5;

[0016] The organic amine is selected from at least one of tetramethylammonium hydroxide, ethylenediamine, triethylamine, ethanolamine, triethanolamine, diethylenetriamine, and triethylenetetramine;

[0017] The alkali metal hydroxide is selected from at least one of potassium hydroxide and sodium hydroxide;

[0018] The guanidine compound is selected from at least one of tetramethylguanidine, trimethylguanidine and guanidine carbonate;

[0019] The low-boiling point organic matter has a boiling point between 60 and 180° C. and is selected from at least one of n-pentane, cyclopentane, n-hexane, cyclohexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, and 2,2,3-trimethylbutane.

[0020] In the mixed solution A, the molar ratio of organosilane to alcohol is 1:0.1-20;

[0021] In the mixed solution B, the molar ratio of the organosilane to the base is 10 to 10000:1;

[0022] In the mixed solution C, the molar ratio of the low boiling point organic matter, the alcohol, and the base is 1:0.1-100:0.1-50;

[0023] In the mixed solution D, the molar ratio of the organosilane to the alcohol is 1:0.1-100;

[0024] The molar ratio of the low boiling point organic matter in the mixed solution C to the organosilane in the mixture B is 0 to 100:1, excluding 0;

[0025] The molar ratio of the alkali in the mixed solution C to the organosilane in the mixed solution B is 0.001 to 10:1

[0026] The molar ratio of the organosilane in the mixed solution D to the alkali in the mixed solution C is 0.1 to 1000:1.

[0027] The stirring speed is 50 to 1500 rpm;

[0028] The reaction temperature is 30 to 120°C;

[0029] Optionally, the reaction temperature is 60 to 120°C;

[0030] The aging temperature is 70-130°C;

[0031] The aging time is 2 to 24 hours.

[0032] The dropping includes dropping the mixed solution C and the mixed solution D into the mixed solution B at the same time, or first dropping the mixed solution C into the mixed solution B, and then dropping the mixed solution D.

[0033] The filter element is made of polytetrafluoroethylene.

[0034] According to another aspect of the present application, a high-purity silica sol prepared by the above-mentioned preparation method is provided, wherein the particle size of the high-purity silica sol is 20 to 150 nm;

[0035] The solid content of the high-purity silica sol is 2-30 wt %.

[0036] According to another aspect of the present application, there is provided an application of the above-mentioned high-purity silica sol for chemical mechanical polishing.

[0037] The beneficial effects of this application include:

[0038] The present invention provides a method for preparing high-purity silica sol, which is mainly used as a polishing liquid component in the chemical mechanical polishing (CMP) process in semiconductor manufacturing. The method forms a high-purity, high-solid content silica sol by directly synthesizing an organosilane in an aqueous solution. The preparation process includes multiple steps of mixing an alkaline solution with an organosilane, heating, aging, and evaporating and removing low-boiling point organic matter. This method avoids the use of a large amount of solvents and the introduction of impurities, improves the purity and consistency of the product, and is suitable for large-scale industrial production. The prepared silica sol has a uniform nanometer-scale particle size (20-150nm) and a high silicon oxide content (more than 20%), which can effectively meet the fine requirements of the CMP process for abrasive particles. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the TEM result diagram in Example 1 of the present application.

[0040] Figure 2 This is the DLS experimental result in Example 1 of the present application. DETAILED DESCRIPTION

[0041] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0042] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0043] The analysis method in the examples of the present application is as follows:

[0044] TEM test was performed using JEM-2100.

[0045] Dynamic light scattering (DLS) particle size and particle size distribution index tests were performed using a Malvern Zeta-sizer Nano instrument (Nano-ZS90, Thermo Fisher Scientific, USA).

[0046] Example 1

[0047] 1) preparing 0.1M and 1M tetramethylammonium hydroxide aqueous solutions;

[0048] 2) Add 710.5 g of deionized water and 24.7 g of 0.1 M tetramethylammonium hydroxide into a three-necked flask, raise the temperature to 80°C, heat under reflux, and stir at 300 rpm;

[0049] 3) Add 150g of mixed solution (TMOS to methanol mass ratio 1:1) at one time, and maintain the temperature at 80°C;

[0050] 4) 98.7 g of 1M tetramethylammonium hydroxide was added dropwise at a rate of 5 ml / min, and then 20 g of a mixture of n-hexane / ethanol (mass ratio of 1:1) was added;

[0051] 5) Add 210 g of the mixed solution (TMOS to methanol mass ratio 1:3) dropwise at a rate of 10.5 ml / min and stir at 80 °C for 5 h;

[0052] 6) heating at 90°C to evaporate and remove n-hexane and alcohol;

[0053] 7) Filtering the prepared sample to remove large particles to obtain a silica sol sample with uniform particle size;

[0054] 8) Adopt the method of constant liquid level heating and concentration, while evaporating the solvent, add the silica sol sample dropwise until the silicon oxide concentration reaches more than 20%.

[0055] Figure 1 This is the TEM result diagram in Example 1 of the present application. As can be seen from the figure, the prepared silicon oxide particles are uniform in size.

[0056] Figure 2 This is the DLS experimental result in Example 1 of the present application. As can be seen from the figure, the prepared silicon oxide particle size distribution is uniform.

[0057] Example 2

[0058] 1) Prepare 0.1M and 1M ethylenediamine aqueous solutions;

[0059] 2) Add 830 g of deionized water and 30.7 g of 0.1 M ethylenediamine to a three-necked flask, heat to 90° C., and stir at 400 rpm;

[0060] 3) Add 120 g of mixed solution (TMOS to methanol mass ratio 1:2) and maintain the temperature at 90°C;

[0061] 4) 108.5 g of 1M ethylenediamine was added dropwise at a rate of 18 ml / min, and then 25 g of a mixture of cyclohexane / isopropanol (mass ratio of 1:1.5) was added;

[0062] 5) Add 500 g of the mixed solution (TMOS to methanol mass ratio 1:10) dropwise at a rate of 15 ml / min and stir at 90 °C for 3 h;

[0063] 6) heating at 90°C to evaporate and remove cyclohexane and alcohol;

[0064] 7) Filtering the prepared sample to remove large particles to obtain a silica sol sample with uniform particle size;

[0065] 8) Adopt the method of constant liquid level heating and concentration, while evaporating the solvent, add the silica sol sample dropwise until the silicon oxide concentration reaches more than 20%.

[0066] Example 3

[0067] 1) preparing 0.1M and 1M tetramethylammonium hydroxide aqueous solutions;

[0068] 2) Add 720 g of deionized water and 35 g of 0.1 M tetramethylammonium hydroxide into a three-necked flask, heat to 80° C., and stir at 500 rpm;

[0069] 3) Add another 150 g of the mixed solution (TMOS to methanol mass ratio 1:5) and maintain the temperature at 80°C;

[0070] 4) 108 g of 1M tetramethylammonium hydroxide was added dropwise at a rate of 1.5 ml / min, and then 15 g of a mixture of 2,2-dimethylbutane / isopropanol (mass ratio of 1.5:1) was added;

[0071] 5) Add 300 g of the mixed solution (TMOS to methanol mass ratio 1:1) at a rate of 11.5 ml / min and stir at 80 °C for 5 h;

[0072] 6) heating at 85°C to evaporate and remove 2,2-dimethylbutane and isopropanol;

[0073] 7) Filtering the prepared sample to remove large particles to obtain a silica sol sample with uniform particle size;

[0074] 8) Adopt the method of constant liquid level heating and concentration, while evaporating the solvent, add the silica sol sample dropwise until the silicon oxide concentration reaches more than 20%.

[0075] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing high-purity silica sol, characterized in that: The following steps are involved: (1) mixing an organosilane with an alcohol to obtain a mixed solution A and a mixed solution D; (2) mixing the alkaline solution with the mixed solution A at 60 to 120° C. to obtain a mixed solution B; (3) mixing the low boiling point organic matter, alcohol and alkaline solution to obtain a mixed solution C; (4) Adding the mixed solution C and the mixed solution D dropwise into the mixed solution B, stirring, reacting, aging, heating and evaporating, filtering, and concentrating to obtain the high-purity silica sol.

2. The preparation method according to claim 1, characterized in that: The organosilane is selected from at least one of tetramethoxysilane and tetraethoxysilane; The alcohol is selected from at least one of methanol, ethanol and isopropanol; The base is selected from at least one of organic amines, alkali metal hydroxides, ammonia water, and guanidine compounds; The pH of the alkaline solution is 7.5 to 12.5; The organic amine is selected from at least one of tetramethylammonium hydroxide, ethylenediamine, triethylamine, ethanolamine, triethanolamine, diethylenetriamine, and triethylenetetramine; The alkali metal hydroxide is selected from at least one of potassium hydroxide and sodium hydroxide; The guanidine compound is selected from at least one of tetramethylguanidine, trimethylguanidine and guanidine carbonate; The low-boiling point organic matter has a boiling point between 60 and 180° C. and is selected from at least one of n-pentane, cyclopentane, n-hexane, cyclohexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, and 2,2,3-trimethylbutane.

3. The preparation method according to claim 1, characterized in that: In the mixed solution A, the molar ratio of the organosilane to the alcohol is 1:0.1-20; In the mixed solution B, the molar ratio of the organosilane to the base is 10 to 10000:1; In the mixed solution C, the molar ratio of the low boiling point organic matter, the alcohol and the base is 1:0.1-100:0.1-50; In the mixed solution D, the molar ratio of the organosilane to the alcohol is 1:0.1-100; The molar ratio of the low boiling point organic matter in the mixed solution C to the organosilane in the mixture B is 0 to 100:1, excluding 0; The molar ratio of the alkali in the mixed solution C to the organosilane in the mixed solution B is 0.001 to 10:1 The molar ratio of the organosilane in the mixed solution D to the alkali in the mixed solution C is 0.1 to 1000:

1.

4. The preparation method according to claim 1, characterized in that: The stirring speed is 50 to 1500 rpm; The reaction temperature is 30 to 120°C; Preferably, the reaction temperature is 60-120°C; The aging temperature is 70-130°C; The aging time is 2 to 24 hours.

5. The preparation method according to claim 1, characterized in that: The dropping includes dropping the mixed solution C and the mixed solution D into the mixed solution B at the same time or first dropping the mixed solution C into the mixed solution B and then dropping the mixed solution D.

6. A high-purity silica sol prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The particle size of the high-purity silica sol is 20 to 150 nm; The solid content of the high-purity silica sol is 2-30 wt %.

7. An application of the high-purity silica sol according to claim 6, characterized in that: Used for chemical mechanical polishing.

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