Preparation method of silica sol, silica sol and application of silica sol

Abstract

The invention discloses a preparation method of silica sol, which comprises the following steps: dropwise adding 4-8wt% of active silicic acid into a silicon seed crystal solution at the temperature of 80-100 DEG C at the speed of increasing 10-15mL / min every 0.2-4 hours, and preparing the wide-particle-size-distribution silica sol with the half-peak width of 30-80nm of a CPS particle size diagram. By controlling the dripping speed of the active silicic acid, controlling the particle size distribution width of the silica sol and controlling the half-peak width of a CPS particle size diagram to be 30-80nm, the polishing solution prepared from the silica sol can have a relatively high grinding rate when being used for grinding oxides.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of silicon dioxide nanomaterials, and more specifically, to a preparation method of silica sol, silica sol and application thereof. Background Art

[0002] Silica sol is a sol liquid formed by uniform dispersion of amorphous silicon dioxide hydrate particles in water, and the particle size is generally between 20 and 100 nm. Due to its high temperature stability, insulation, water resistance, and pollution-free properties, silica sol is widely used in textile, coating, papermaking, rubber, ceramics, precision casting, and electronics industries. Different industries have different requirements for the purity of silica sol. The semiconductor industry has extremely high requirements for the purity of silica sol. Ultra-high purity silica sol is mainly used in the semiconductor industry, such as precision polishing of silicon wafers, germanium wafers, etc., chemical mechanical planarization (CMP) process of integrated circuits, etc. It is one of the indispensable consumables in the microelectronics industry.

[0003] In the process of chemical mechanical polishing, polishing liquid is one of the important factors affecting global planarization. Colloidal silica, as the most widely used nano-abrasive in CMP polishing liquid, plays a vital role in CMP performance. The narrow particle size and monodisperse distribution of abrasives currently used in the market can hardly meet the needs of some applications. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] Another object of the present invention is to provide a method for preparing silica sol. By controlling the dripping speed of active silicic acid, controlling the particle size distribution width of the silica sol, and controlling the half-peak width of the CPS particle size diagram to be between 30 and 80 nm, the polishing liquid prepared by the silica sol can have a higher grinding rate when grinding oxides.

[0006] In order to achieve these objects and other advantages according to the present invention, a method for preparing a silica sol is provided, comprising the following steps: adding active silicic acid having a content of 4 to 8 wt % to a silicon seed solution at a temperature of 80 to 100° C. at a rate of 10 to 15 mL / min per time every 0.2 to 4 hours to prepare a silica sol with a wide particle size distribution having a half-peak width of a CPS particle size diagram between 30 and 80 nm.

[0007] Preferably, the method further comprises: preparing a mixed aqueous solution using ultrapure water and polyhydroxy aromatic carboxylic acid, adding the mixed aqueous solution into the silica sol, and then adding ultrapure water thereto for replacement, and repeating this process at least twice.

[0008] Preferably, the polyhydroxy aromatic carboxylic acid is at least one of 2,4-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and 2,3-dihydroxybenzoic acid.

[0009] Preferably, the mixed aqueous solution contains 0.1 to 0.5 wt % of polyhydroxy aromatic carboxylic acid.

[0010] Preferably, the temperature of the mixed aqueous solution is 60-70°C.

[0011] Preferably, the mass ratio of the mixed aqueous solution to the silica sol is (1000-5000):1.

[0012] Preferably, the initial dropping speed of the active silicic acid is 13-18 mL / min;

[0013] The content of the active silicate is 4-8wt%, pH=2-3;

[0014] The active silicic acid is prepared by diluting high-purity sodium water glass with ultrapure water until the silicon dioxide content is 5 to 10 wt %;

[0015] Preferably, the high-purity sodium water glass has a solid content of 35-40wt%, a Na2O content of 8-15wt%, and a modulus of 2.8-3.4.

[0016] Preferably, the silicon seed solution is prepared by adding a catalyst to ultrapure water and adjusting the pH to 11-13, heating to 80-100° C., adding active silicic acid, and reacting at a constant temperature for 2-4 hours.

[0017] Preferably, the catalyst comprises one or more of sodium hydroxide, potassium hydroxide, potassium silicate and sodium silicate.

[0018] A second aspect of the present invention provides a silica sol with a wide particle size distribution.

[0019] A third aspect of the present invention provides an application of silica sol with a wide particle size distribution in a semiconductor CMP polishing liquid.

[0020] The present invention has at least the following beneficial effects:

[0021] 1. By controlling the dropping speed of active silicate, controlling the particle size distribution width of silica sol, controlling the half-peak width of the CPS particle size diagram between 30 and 80 nm, and the polydispersity index (PDI) between 1.2 and 1.5, the polishing liquid prepared by the silica sol can have a higher polishing rate when grinding oxides;

[0022] 2. Since the present invention uses alkaline metal ion compounds as catalysts and uses ultrapure aqueous solutions prepared with polyhydroxy aromatic carboxylic acids, the content of metal ions in silica sol can be reduced, and the number of defects on the wafer can be reduced during polishing.

[0023] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the CPS particle size distribution diagram of Example 1 of the present invention;

[0025] Figure 2 This is the CPS particle size distribution diagram of Example 2 of the present invention;

[0026] Figure 3 This is the CPS particle size distribution diagram of Example 3 of the present invention;

[0027] Figure 4 This is the CPS particle size distribution diagram of Example 4 of the present invention;

[0028] Figure 5 This is the CPS particle size distribution diagram of Comparative Example 1 of the present invention;

[0029] Figure 6 This is the CPS particle size distribution diagram of comparative example 2 of the present invention;.

[0030] Figure 7 This is the CPS particle size distribution diagram of comparative example 3 of the present invention DETAILED DESCRIPTION

[0031] In order to better understand the technical solution of the present invention, the present invention is described in detail below.

[0032] The present invention provides a method for preparing silica sol, comprising the following steps:

[0033] S1, diluting high-purity sodium water glass with ultrapure water to a silicon dioxide content of 5-10wt%, passing through a cation exchange resin, and then diluting with ultrapure water to obtain active silicate with a pH of 2-3 and a content of 4-8wt%;

[0034] The content of silicon dioxide is measured by molybdate photometry. The mass content of silicon dioxide will affect the ion exchange process. Different contents of silicic acid can affect the particle size distribution of silica sol and the morphology of silicon dioxide particles in silica sol. In an embodiment of the present invention, high-purity sodium water glass is diluted to a silicon dioxide content of 5-10wt% and then subjected to ion exchange resin to provide a mass content guarantee for the preparation of 4-8wt% active silicate, ensure the particle size distribution and morphology of silica sol, and reduce the waste of silicon source. The solid content of the high-purity sodium water glass is 35-40wt%, the Na2O content is 8-15wt%, and the modulus is 2.8-3.4. The modulus of sodium oxide refers to the ratio of the molar concentration of silicon dioxide in water glass to the molar concentration of sodium oxide. The calculation formula of the modulus of sodium oxide is: M=[SiO2] / [Na2O], where [SiO2] and [Na2O] represent the molar concentrations of silicon dioxide and sodium oxide, respectively. The use of high-purity sodium water glass with this content enables the cations therein to be exchanged more effectively.

[0035] In some embodiments of the present invention, active silicate is relatively stable under acidic conditions. The regeneration of cation exchange resin generally uses HCl, but the regeneration process produces a large amount of Cl-containing - The waste liquid is difficult to handle. In order to solve the problem of wastewater discharge, the regeneration agent is changed to H2SO4.

[0036] The ultrapure water used above has a resistivity of ≥10 MΩ·cm, preferably 12.5 MΩ·cm. The ultrapure water used below has the same resistivity requirement as the ultrapure water used in this embodiment.

[0037] S2, adding a catalyst to ultrapure water, heating to 80-100° C., adjusting the pH to 11-13, adding active silicic acid when heated to 80-100° C., and reacting at a constant temperature for 2-4 hours to prepare a silicon seed solution;

[0038] The particle size of the particles in the silicon seed solution is determined by the particle size of the silica sol to be prepared. In some embodiments of the present invention, the particle size of the particles in the silicon seed solution is between 5 and 20 nm, preferably between 5 and 18 nm.

[0039] The catalyst includes one or more of sodium hydroxide, potassium hydroxide, potassium silicate, and sodium silicate. During the preparation process, if the pH is lower than 11, the catalyst can be added in time to maintain the pH between 11 and 13.

[0040] S3. First, 4-8 wt% active silicate is added dropwise at a rate of 13-18 mL / min to a silicon seed solution at a temperature of 80-100°C, and then the reaction is continued dropwise at a rate of 10-15 mL / min every 0.2-4 hours. The active silicate is added dropwise continuously without interruption during the segmented addition. After the addition is completed, the reaction is continued for 4-12 hours to obtain a silica sol with a wide particle size distribution and a half-peak width of the CPS particle size diagram between 30 and 80 nm.

[0041] The present invention uses a stepwise increasing dropping rate to drop 4-8 wt% of active silicic acid, controls the half peak width of the CPS particle size diagram of the silica sol to be between 30-80 nm, and the polydispersity index (PDI) to be between 1.2 and 1.5.

[0042] Step S4, prepare a mixed aqueous solution using ultrapure water and polyhydroxy aromatic carboxylic acid, add the mixed aqueous solution to the silica sol in step S3, then add ultrapure water to replace it, and repeat the above steps twice. The present invention uses a mixed aqueous solution to reduce the content of metal particles in the silica sol and avoid its influence on the subsequent chip processing technology; the present invention uses a mixed aqueous solution to reduce the number of defects on the wafer during polishing

[0043] In some embodiments of the present invention, non-limiting examples of the polyhydroxy aromatic carboxylic acid include at least one of 2,4-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and 2,3-dihydroxybenzoic acid. Preferably, the polyhydroxy aromatic carboxylic acid is a polymer of 3,4-dihydroxybenzoic acid or 3,5-dihydroxybenzoic acid.

[0044] In some embodiments of the present invention, the mixed aqueous solution contains 0.1-0.5 wt% of polyhydroxy aromatic carboxylic acid, which can be 0.1 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.18 wt%, 0.20 wt%, 0.22 wt%, 0.25 wt%, 0.28 wt%, 0.30 wt%, 0.32 wt%, 0.35 wt%, 0.38 wt%, 0.40 wt%, 0.42 wt%, 0.45 wt%, 0.48 wt%, 0.50 wt%. The temperature of the mixed aqueous solution is 60-70 ° C. The mass ratio of the mixed aqueous solution to the silica sol in step S3 is (1000-5000): 1.

[0045] In some embodiments of the present invention, the solvent replacement is carried out by ultrafiltration membrane concentration.

[0046] The invention provides a silica sol with a wide particle size distribution prepared by a method for preparing silica sol, wherein the half peak width of a CPS particle size diagram of the silica sol is between 30 and 80 nm, preferably between 30 and 79 nm, preferably between 31 and 79 nm, and the polydispersity index (PDI) is between 1.2 and 1.5.

[0047] The invention provides a method for preparing silica sol and application of the silica sol with wide particle size distribution prepared by the method in semiconductor CMP polishing liquid.

[0048] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0049] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0050] <Example 1>

[0051] Preparation of active silicate: high-purity sodium water glass is diluted with ultrapure water to a silica mass fraction of 9%, passed through a cation exchange resin H2SO4, and diluted with ultrapure water to a mass fraction of 6% active silicate, with a pH of 2.36;

[0052] Preparation of silicon seed solution: add 680g ultrapure water into a 10000ml four-necked flask, heat to 100°C, add 15g KOH, then add 1000mL 6 wt% active silicic acid, stir evenly, react at constant temperature for 180min, and stir at a speed of 150r / min to obtain a silicon seed solution;

[0053] Preparation of silica sol with wide particle size distribution: the stirring speed is adjusted to 200r / min, and then the heating is continued to maintain 100°C. 3600mL of the above-mentioned active silicic acid is taken and added dropwise to the silicon seed solution with a peristaltic pump at a dropping rate of 15mL / min. The addition is completed in about 4 hours. After the addition is completed, 60g KOH is added and stirred evenly. Then 3600mL of active silicic acid is added dropwise to the system at a dropping rate of 30mL / min. The addition is completed in about 2 hours. After the addition is completed, stir at a constant temperature of 100°C for 0.5h. The reaction time is about 10h. Stop heating, the reaction is completed, and a silica sol with a wide particle size distribution is obtained. The particle size distribution is 32.7-99.7nm, the average particle size is 59.9nm, the half-peak width of the CPS particle size diagram is 57.6nm, and the PDI is 1.226.

[0054] <Example 2>

[0055] The preparation of active silicic acid is the same as in Example 1;

[0056] Preparation of silicon seed solution: add 720g ultrapure water into a 10000ml four-necked flask, heat to 100°C, add 10g KOH, then add 900mL active silicic acid, stir evenly, react at constant temperature for 180min, and stir at a speed of 150r / min to obtain a silicon seed solution;

[0057] Preparation of silica sol with wide particle size distribution: the stirring speed is adjusted to 200r / min, and then the heating is continued to maintain 100°C. 900mL of the above-mentioned active silicic acid is taken and added dropwise to the silicon seed solution with a peristaltic pump at a dropping rate of 15mL / min. The addition is completed in about 60min. Then 2400mL of active silicic acid is taken and added dropwise to the system at a dropping rate of 30mL / min. The addition is completed in about 80min. After the addition is completed, 60g KOH is added, and then 2400mL of active silicic acid is taken and added dropwise to the system at a dropping rate of 40mL / min. The addition is completed in about 60min. The reaction time is about 10h. Stop heating and the reaction is completed to obtain a silica sol with a wide particle size distribution. The particle size distribution is 31.0-103.9nm, the average particle size is 52.2nm, the half-peak width of the CPS particle size diagram is 40.0nm, and the PDI is 1.253.

[0058] <Example 3>

[0059] The preparation of active silicic acid is the same as in Example 1;

[0060] Preparation of silicon seed solution: add 506g ultrapure water into a 10000ml four-necked flask, add 25g potassium silicate, heat to 100°C, adjust the stirring speed to 200r / min, take 1200mL active silicic acid, add it dropwise into the bottom liquid with a peristaltic pump at a drop rate of 60mL / min, add it in about 20min, and react at a constant temperature for 180min to obtain a silicon seed solution;

[0061] Preparation of silica sol with wide particle size distribution: the stirring speed is adjusted to 200r / min, heating is continued to maintain 100°C, 3000mL of active silicic acid is taken and added dropwise to the silicon seed solution by a peristaltic pump at a dropping rate of 15mL / min, and the addition is completed in about 200min. After the addition is completed, 60g of KOH is added, and then 3000mL of active silicic acid is taken and added dropwise to the system at a dropping rate of 30mL / min. The addition is completed in about 100min. The reaction time is about 10h, and heating is stopped. The reaction is terminated to obtain a silica sol with a wide particle size distribution, with a particle size distribution of 31.3-143nm, an average particle size of 71.1nm, a half-peak width of the CPS particle size diagram of 78.9nm, and a PDI of 1.470.

[0062] <Example 4>

[0063] The preparation of active silicic acid is the same as in Example 1;

[0064] Preparation of silicon seed solution: add 506g ultrapure water into a 10000ml four-necked flask, add 15g potassium silicate, add 5g KOH, heat to 100°C, adjust the stirring speed to 200r / min, take 1200mL active silicic acid, add it dropwise into the bottom liquid with a peristaltic pump at a drop rate of 60mL / min, add it in about 20min, keep the temperature constant for 180min, and obtain a silicon seed solution;

[0065] Preparation of silica sol with wide particle size distribution: the stirring speed is adjusted to 200r / min, and heating is continued to maintain 100°C. 3000mL of active silicic acid is taken and added dropwise to the silicon seed solution by a peristaltic pump at a dropping rate of 15mL / min. The addition is completed in about 200min. After the addition is completed, 60g of KOH is added, and then 2400mL of active silicic acid is taken and added dropwise to the system at a dropping rate of 30mL / min. The addition is completed in about 80min. The reaction time is about 10h. Stop heating and the reaction is completed to obtain a silica sol with a wide particle size distribution. The particle size distribution is 30.6-113.6nm, the average particle size is 51.8nm, the half-peak width of the CPS particle size diagram is 31.4nm, and the PDI is 1.274.

[0066] <Example 5>

[0067] The same as Example 4, except that, after preparing the silica sol with a wide particle size distribution, the method further includes: preparing a mixed aqueous solution of ultrapure water containing 0.2 wt% of 3,4-dihydroxybenzoic acid, adding the mixed aqueous solution to the silica sol, wherein the mass ratio of the mixed aqueous solution to the silica sol is 3000:1, and then adding ultrapure water thereto for replacement, wherein the replacement is concentrated by ultrafiltration membrane, and the replacement is repeated twice.

[0068] <Example 6>

[0069] The same as Example 4, except that after preparing the silica sol with a wide particle size distribution, the method further includes: preparing an ultrapure water mixed aqueous solution containing 0.1 wt% of 3,5-dihydroxybenzoic acid, adding the 60°C mixed aqueous solution to the silica sol, wherein the mass ratio of the mixed aqueous solution to the silica sol is 2000:1, and then adding ultrapure water thereto for replacement, wherein the replacement is concentrated by ultrafiltration membrane, and the replacement is repeated twice.

[0070] <Example 7>

[0071] The preparation is the same as that of Example 4, except that after the silica sol with a wide particle size distribution is prepared, ultrapure water is added to the silica sol for replacement, the mass ratio of ultrapure water to silica sol is 2000:1, the replacement is concentrated by ultrafiltration membrane, and the replacement is repeated twice.

[0072] <Comparative Example 1>

[0073] Preparation of active silicate: high-purity sodium water glass is diluted with ultrapure water to a silica mass fraction of 9%, passed through a cation exchange resin H2SO4, and diluted with ultrapure water to a mass fraction of 2% active silicate, with a pH of 2.56;

[0074] The preparation method of silicon seed solution and silica sol is the same as that of Example 1, and a silica sol with a narrow particle size distribution is prepared. The particle size distribution is 31.3-59.5 nm, the average particle size is 43.1 nm, the half peak width of the CPS particle size diagram is 16.2 nm, and the PDI is 1.067.

[0075] <Comparative Example 2>

[0076] Preparation of active silicate: dilute high-purity sodium water glass with ultrapure water to a silica mass fraction of 12%, pass through a cation exchange resin H2SO4, and adjust with ultrapure water to a mass fraction of 9% active silicate, with a pH of 2.16;

[0077] The preparation method of silicon seed solution and silica sol is the same as that of Example 1, and silica sol is prepared, with a particle size distribution of 28.6-104.7 nm, an average particle size of 44.3 nm, a half-peak width of 18.5 nm, and a PDI of 1.105.

[0078] <Comparative Example 3>

[0079] The preparation of active silicic acid and silicon seed solution is the same as that in Example 1, except that, when preparing silica sol, the stirring speed is adjusted to 200 r / min, and then heating is continued at 100°C. 7200 mL of active silicic acid is taken and added dropwise to the silicon seed solution by a peristaltic pump at a dropping rate of 30 mL / min. After the addition is completed, stirring is carried out at a constant temperature of 100°C for 0.5 h, and heating is stopped. The reaction is terminated to obtain silica sol with a particle size distribution of 35.0-72.7 nm, an average particle size of 47.5 nm, a half-peak width of the CPS particle size diagram of 20.0 nm, and a PDI of 1.086.

[0080] <Comparative Example 4>

[0081] The preparation of active silicic acid and silicon seed solution is the same as that in Example 1, except that, when preparing silica sol, the stirring speed is adjusted to 200 r / min, and then heating is continued at 100°C. 7200 mL of active silicic acid is first added dropwise to the silicon seed solution using a peristaltic pump at a dropping speed of 15 mL / min, and the addition is continued for 60 min, and then at a dropping speed of 45 mL / min. After the addition is completed, the mixture is stirred at a constant temperature of 100°C for 0.5 h, and the heating is stopped. The reaction is terminated to obtain silica sol with a particle size distribution of 65.0-98.7 nm, an average particle size of 82.5 nm, a half-peak width of the CPS particle size diagram of 15.8 nm, and a PDI of 1.028.

[0082] <Comparative Example 5>

[0083] The preparation of active silicic acid and silicon seed solution is the same as that in Example 1, except that, when preparing silica sol, the stirring speed is adjusted to 200 r / min, and then heating is continued at 100°C. 7200 mL of active silicic acid is first added dropwise to the silicon seed solution using a peristaltic pump at a dropping speed of 15 mL / min, and the addition is continued for 60 min, and then at a dropping speed of 20 mL / min. After the addition is completed, the mixture is stirred at a constant temperature of 100°C for 0.5 h, and the heating is stopped. The reaction is terminated to obtain silica sol with a particle size distribution of 45.0-72.1 nm, an average particle size of 62.3 nm, a half-peak width of the CPS particle size diagram of 14.2 nm, and a PDI of 1.034.

[0084] <Evaluation method>

[0085] Metal ion content: The silica sol products of Examples 1 to 7 and Comparative Examples 1 to 5 were selected and tested using an ICP-OES instrument.

[0086] Polishing liquid preparation method: adjust the silica sol prepared by the present invention to a silicon dioxide content of 10wt%, add 0.1wt% H2O2, adjust the pH value to 10.50 with 5wt% ammonia water, and stir evenly to obtain the polishing liquid.

[0087] Polishing experiment: The polished wafers loaded with TEOS were attached to the polishing head by back film adsorption method. The polishing parameters were set as follows: polishing pressure was 6 psi, carrier speed was 100 rpm; platen speed was 90 rpm; polishing liquid flow rate was 125 ml / min. The polishing rate and defectivity were measured, and the results are listed in Table 1.

[0088] Removal Rate: The removal rate (RR) is determined by the amount removed in one minute of polishing.

[0089] Defectivity test method: Defectivity is the measurement of the number of defects on the wafer. The instrument used is KLA-Tencor SP2 analyzer, which records the average number of defects in 10 wafers.

[0090] Table 1

[0091]

[0092]

[0093] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing silica sol, characterized in that: The method comprises the following steps: adding active silicic acid with a content of 4 to 8 wt % to a silicon seed solution at 80 to 100° C. at a rate of 10 to 15 mL / min every 0.2 to 4 hours to prepare a wide particle size distribution silica sol with a half peak width of a CPS particle size diagram between 30 and 80 nm.

2. The method for preparing silica sol according to claim 1, characterized in that: Also includes: A mixed aqueous solution is prepared by using ultrapure water and polyhydroxy aromatic carboxylic acid, the mixed aqueous solution is added into silica sol, and then ultrapure water is added thereto for replacement, and this process is repeated at least twice.

3. The method for preparing silica sol according to claim 2, characterized in that: The polyhydroxy aromatic carboxylic acid is at least one of 2,4-dihydroxybenzoic acid, 2,6-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid and 2,3-dihydroxybenzoic acid.

4. The method for preparing silica sol according to claim 2, characterized in that: The mixed aqueous solution contains 0.1-0.5 wt % of polyhydroxy aromatic carboxylic acid. Preferably, the temperature of the mixed aqueous solution is 60-70°C.

5. The method for preparing silica sol according to claim 2, characterized in that: The mass ratio of the mixed aqueous solution to the silica sol is (1000-5000):

1.

6. The method for preparing silica sol according to claim 1, characterized in that: The initial dropping speed of the active silicic acid is 13-18 mL / min; The active silicic acid is prepared by diluting high-purity sodium water glass with ultrapure water until the silicon dioxide content is 5 to 10 wt %; Preferably, the high-purity sodium water glass has a solid content of 35-40wt%, a Na2O content of 8-15wt%, and a modulus of 2.8-3.

4.

7. The method for preparing silica sol according to claim 1, characterized in that: The silicon seed solution is prepared by adding a catalyst to ultrapure water and adjusting the pH to 11-13, heating to 80-100° C., adding active silicic acid, and reacting at a constant temperature for 2-4 hours.

8. The method for preparing silica sol according to claim 7, characterized in that: The catalyst includes one or more of sodium hydroxide, potassium hydroxide, potassium silicate and sodium silicate.

9. A silica sol with a wide particle size distribution prepared by the method for preparing a silica sol according to any one of claims 1 to 8.

10. Use of the silica sol with a wide particle size distribution as claimed in claim 9 in a semiconductor CMP polishing liquid.

Images