A high-purity silica sol for chemical mechanical polishing and its preparation method

Abstract

This application relates to the field of silica sol, and specifically discloses a high-purity silica sol for chemical mechanical polishing and a preparation method thereof. The high-purity silica sol for chemical mechanical polishing is prepared by reacting the following components: organosilicon monomer, sodium polyacrylate, 1H,1H,2H,2H-perfluorooctyltriethoxysilane, solvent and catalyst. The high-purity silica sol for chemical mechanical polishing of this application has a particle size range suitable for chemical mechanical polishing, is not prone to agglomeration and sedimentation by adding sodium polyacrylate and 1H,1H,2H,2H-perfluorooctyltriethoxysilane to the silica sol system, and the two play a synergistic effect in the silica sol formula, and the final prepared high-purity silica sol for chemical mechanical polishing has a better polishing effect when used for chemical mechanical polishing of silicon wafers.

Description

Technical Field

[0001] The present invention relates to a silica sol and a preparation method thereof, and particularly to a high-purity silica sol for chemical mechanical polishing and a preparation method thereof. Background Art

[0002] With the rapid development of fields such as the semiconductor industry, microelectronics manufacturing, optical instruments, and precision machining, higher and higher requirements are put forward for the flatness and smoothness of the material surface. As an important surface treatment technology, chemical mechanical polishing (CMP) technology has been widely used in these fields due to its efficient and precise polishing effect. The CMP technology realizes the super-smooth treatment of the workpiece surface through the synergistic action of the oxidation of chemical reagents and mechanical friction, greatly improving the quality and performance of products.

[0003] In the CMP technology, the polishing liquid is a crucial component, and silica sol, as one of the main components of the polishing liquid, has unique advantages. Silica sol is a colloidal dispersion formed by nano-SiO 2 particles dispersed in water (or organic solvents), and its internal Si-O-Si bond structure endows it with good stability and dispersibility. In addition, the SiO 2 abrasive grains have the characteristics of moderate hardness, small particle size, large specific surface area, excellent permeability, etc. These characteristics make silica sol perform excellently in the CMP polishing process. Specifically, the silica sol polishing liquid can effectively reduce the surface roughness and the depth of the damaged layer, improve the polishing uniformity and the material removal rate, and at the same time has good fluidity, which is helpful for cleaning and chip removal after polishing.

[0004] However, although silica sol shows many advantages in CMP polishing, it still faces some problems and defects in practical applications. First of all, due to the strong interaction between the existing nano-SiO 2 particles, agglomeration is likely to occur, resulting in uneven particle distribution in the polishing liquid and affecting the polishing effect. Secondly, silica sol is prone to precipitation or stratification under conditions such as long-term storage, affecting the stability and service life of the polishing liquid.

[0005] Therefore, in view of the above problems, it is urgent to develop a high-purity silica sol for chemical mechanical polishing and a preparation method thereof, which has the characteristics of being not easy to agglomerate and settle, and the advantage of good polishing effect. Summary of the Invention

[0006] Aiming at the defects existing in the above-mentioned prior art, an object of the present invention is to provide a high-purity silica sol for chemical mechanical polishing and a preparation method thereof, aiming to solve the technical problems of easy agglomeration, easy settlement, and poor polishing effect of the existing silica sol.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0009] Organosilicon monomer: 100 parts

[0010] Sodium polyacrylate: 1 - 3 parts

[0011] Tridecafluorooctyltriethoxysilane: 4 - 15 parts

[0012] Solvent: 100 - 250 parts

[0013] Catalyst: 0.1 - 5 parts by mass.

[0014] The organosilicon monomer is selected from at least one of tetraethyl orthosilicate, methyltriethoxysilane, and dimethyldimethoxysilane;

[0015] Preferably, the mass ratio of sodium polyacrylate to tridecafluorooctyltriethoxysilane is 1:(3 - 5);

[0016] More preferably, the mass ratio of sodium polyacrylate to tridecafluorooctyltriethoxysilane is 1:4;

[0017] The solvent is a mixture of ethanol and deionized water, and the mass ratio of ethanol to deionized water is 1:(1.5 - 3);

[0018] Preferably, the mass ratio of ethanol to deionized water is 1:2.

[0019] The catalyst is an ammonia water solution.

[0020] The second object of the present invention is to provide a preparation method of the above high-purity silica sol for chemical mechanical polishing, including the following preparation steps:

[0021] (1) Weigh the organosilicon monomer, sodium polyacrylate, tridecafluorooctyltriethoxysilane, solvent, and catalyst according to the above formula;

[0022] (2) Add the solvent to a container, start stirring, add the catalyst to adjust the pH of the system to 9 - 10, dropwise add the organosilicon monomer while stirring, and carry out a hydrolysis and polycondensation reaction for 2 - 8 h under the control of a stepwise temperature increase program while stirring. Then add sodium polyacrylate, stir and react at 95°C for 2 - 3 h, then add tridecafluorooctyltriethoxysilane and continue to stir and react at 95°C for 2 - 3 h to obtain the high-purity silica sol for chemical mechanical polishing.

[0023] Preferably, the stepwise temperature increase program is to react at 60 - 80°C for 2 - 3 h, and then react at 85 - 90°C for 2 - 5 h.

[0024] The third object of the present invention is to provide a chemical mechanical polishing liquid, which comprises the above-mentioned high-purity silica sol for chemical mechanical polishing.

[0025] The fourth object of the present invention is to provide an application of the high-purity silica sol for chemical mechanical polishing in improving the polishing effect of the chemical mechanical polishing liquid.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The inventor of the present invention creatively adds sodium polyacrylate and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane to the system of the high-purity silica sol for chemical mechanical polishing. On the one hand, the carboxyl groups on the molecular chain of sodium polyacrylate form hydrogen bonds with water molecules and adsorb on the particle surface, and the electrostatic repulsion and steric hindrance effects prevent particle aggregation, thereby maintaining the stable dispersion of the silica particles in the solvent. On the other hand, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane, as a fluorinated silane, has a low surface energy, and the fluorinated end groups can repel each other after reacting on the surface of the silica particles, making the silica sol stably dispersed. At the same time, by using the synergistic effect of sodium polyacrylate and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane, the silica sol has a better average particle size (70 nm - 80 nm), a relatively narrow particle size distribution, that is, a relatively small span (≤0.13), better sedimentation resistance (can withstand a three-month storage stability test without precipitation), and better polishing effect.

[0028] (2) The inventor of the present invention creatively adopts a stepwise temperature rising program in the process of preparing the silica sol. First, react at a low temperature for a certain period of time, and then raise the temperature to a high temperature for a certain period of time. Due to the different growth rates of the silica particle crystal nuclei at different temperatures, the finally obtained silica sol has uniform particle size, narrow particle size distribution, is not easy to agglomerate and settle, and has a good polishing effect. Specific Embodiments

[0029] To better illustrate the object, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0030] The selection of each raw material is as follows:

[0031] The organosilicon monomer is selected as tetraethyl orthosilicate (TEOS);

[0032] The sodium polyacrylate is Sokalan PA 25CL-FR of BASF;

[0033] The 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane is S00805 of Shanghai Shiyang Chemical Co., Ltd.;

[0034] The solvent is a mixture of ethanol and deionized water with a mass ratio of 1:2;

[0035] The catalyst is ammonia water.

[0036] Example 1

[0037] The preparation of high-purity silica sol for chemical mechanical polishing is obtained by the reaction of the following components in parts by mass:

[0038] First step, weigh each raw material according to the following parts by mass

[0039] 100 parts of TEOS

[0040] 2 parts of sodium polyacrylate

[0041] 6 parts of tridecafluorooctyltriethoxysilane

[0042] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0043] 1.5 parts of ammonia water

[0044] Second step, hydrolysis reaction:

[0045] Add the solvent to the container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring. First, react at 60 °C for 3 h, then heat to 85 °C and react for 3 h. Then add sodium polyacrylate, stir and react at 95 °C for 2 h, and then add tridecafluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain high-purity silica sol for chemical mechanical polishing.

[0046] Example 2

[0047] The preparation of high-purity silica sol for chemical mechanical polishing is obtained by the reaction of the following components in parts by mass:

[0048] First step, weigh each raw material according to the following parts by mass

[0049] 100 parts of TEOS

[0050] 2 parts of sodium polyacrylate

[0051] 8 parts of tridecafluorooctyltriethoxysilane

[0052] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0053] 1.5 parts of ammonia water

[0054] Second step, hydrolysis reaction:

[0055] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, then heat to 85 °C and react for 3 h. Then add sodium polyacrylate, stir and react at 95 °C for 2 h, add 1H,1H,2H,2H-perfluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain high-purity silica sol for chemical mechanical polishing.

[0056] Example 3

[0057] Preparation of high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0058] First step, weigh each raw material according to the following parts by mass

[0059] 100 parts of TEOS

[0060] 2 parts of sodium polyacrylate

[0061] 10 parts of 1H,1H,2H,2H-perfluorooctyltriethoxysilane

[0062] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0063] 1.5 parts of ammonia water

[0064] Second step, hydrolysis reaction:

[0065] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, then heat to 85 °C and react for 3 h. Then add sodium polyacrylate, stir and react at 95 °C for 2 h, add 1H,1H,2H,2H-perfluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain high-purity silica sol for chemical mechanical polishing.

[0066] Example 4

[0067] Preparation of high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0068] First step, weigh each raw material according to the following parts by mass

[0069] 100 parts of TEOS

[0070] 1 part of sodium polyacrylate

[0071] 4 parts of 1H,1H,2H,2H-perfluorooctyltriethoxysilane

[0072] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0073] 1.5 parts of ammonia water

[0074] Step 2, hydrolysis reaction:

[0075] Add a solvent to the container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, then heat to 85 °C and react for 3 h. Then add sodium polyacrylate, stir and react at 95 °C for 2 h, add 1H,1H,2H,2H-perfluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain high-purity silica sol for chemical mechanical polishing.

[0076] Example 5

[0077] Preparation of high-purity silica sol for chemical mechanical polishing, obtained by reacting the following components in parts by mass:

[0078] Step 1, weigh each raw material according to the following parts by mass

[0079] 100 parts of TEOS

[0080] 3 parts of sodium polyacrylate

[0081] 12 parts of 1H,1H,2H,2H-perfluorooctyltriethoxysilane

[0082] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0083] 1.5 parts of ammonia water

[0084] Step 2, hydrolysis reaction:

[0085] Add a solvent to the container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, then heat to 85 °C and react for 3 h. Then add sodium polyacrylate, stir and react at 95 °C for 2 h, add 1H,1H,2H,2H-perfluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain high-purity silica sol for chemical mechanical polishing.

[0086] Comparative Example 1

[0087] Preparation of high-purity silica sol for chemical mechanical polishing, obtained by reacting the following components in parts by mass:

[0088] Step 1, weigh each raw material according to the following parts by mass

[0089] 100 parts of TEOS

[0090] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0091] 1.5 parts of ammonia water

[0092] Step 2, hydrolysis reaction:

[0093] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, and dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, and then heat it to 85 °C and react for 3 h to obtain a high-purity silica sol for chemical mechanical polishing.

[0094] Comparative Example 2

[0095] The preparation of a high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0096] First step, weigh each raw material according to the following parts by mass

[0097] 100 parts of TEOS

[0098] 10 parts of sodium polyacrylate

[0099] 150 parts of a solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0100] 1.5 parts of ammonia water

[0101] Second step, hydrolysis reaction:

[0102] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, and dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, and then heat it to 85 °C and react for 3 h. Then add sodium polyacrylate to it and stir and react at 95 °C for 2 h to obtain a high-purity silica sol for chemical mechanical polishing.

[0103] Comparative Example 3

[0104] The preparation of a high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0105] First step, weigh each raw material according to the following parts by mass

[0106] 100 parts of TEOS

[0107] 10 parts of 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane

[0108] 150 parts of a solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0109] 1.5 parts of ammonia water

[0110] Second step, hydrolysis reaction:

[0111] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, and dropwise add TEOS while stirring. First, keep the reaction at 60 °C for 3 h, and then heat it to 85 °C and react for 3 h. Then add 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane to it and stir and react at 95 °C for 3 h to obtain a high-purity silica sol for chemical mechanical polishing.

[0112] Comparative Example 4

[0113] Preparation of a high-purity silica sol for chemical mechanical polishing, obtained by reacting the following components in parts by mass:

[0114] First step, weigh each raw material according to the following parts by mass

[0115] 100 parts of TEOS

[0116] 2 parts of sodium polyacrylate

[0117] 10 parts of tridecafluorooctyltriethoxysilane

[0118] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0119] 1.5 parts of ammonia water

[0120] Second step, hydrolysis reaction:

[0121] Add the solvent to the container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring, keep reacting at 60 °C for 6 h, then add sodium polyacrylate to it, stir and react at 95 °C for 2 h, then add tridecafluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain the high-purity silica sol for chemical mechanical polishing.

[0122] Comparative Example 5

[0123] Preparation of a high-purity silica sol for chemical mechanical polishing, obtained by reacting the following components in parts by mass:

[0124] First step, weigh each raw material according to the following parts by mass

[0125] 100 parts of TEOS

[0126] 2 parts of sodium polyacrylate

[0127] 10 parts of tridecafluorooctyltriethoxysilane

[0128] 150 parts of solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0129] 1.5 parts of ammonia water

[0130] Second step, hydrolysis reaction:

[0131] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring, heat to 85 °C and react for 6 h, then add sodium polyacrylate thereto, stir and react at 95 °C for 2 h, add tridecafluorooctyltriethoxysilane and continue to stir and react at 95 °C for 3 h to obtain a high-purity silica sol for chemical mechanical polishing.

[0132] Comparative Example 6

[0133] The preparation of a high-purity silica sol for chemical mechanical polishing is obtained by reacting the following components in parts by mass:

[0134] First step, weigh each raw material according to the following parts by mass

[0135] 100 parts of TEOS

[0136] 2 parts of sodium polyacrylate

[0137] 10 parts of tridecafluorooctyltriethoxysilane

[0138] 150 parts of a solvent (a mixture of ethanol and deionized water with a mass ratio of 1:2)

[0139] 1.5 parts of ammonia water

[0140] Second step, hydrolysis reaction:

[0141] Add a solvent into a container, start stirring, add ammonia water to adjust the pH value to 9.5, dropwise add TEOS while stirring, first keep reacting at 60 °C for 3 h, then heat to 85 °C and react for 3 h, then add tridecafluorooctyltriethoxysilane thereto, stir and react at 95 °C for 2 h, add sodium polyacrylate and continue to stir and react at 95 °C for 3 h to obtain a high-purity silica sol for chemical mechanical polishing.

[0142] Performance test:

[0143] Particle size measurement: The average particle size and the particle size distribution range are tested by a laser nano-particle size analyzer. The particle size distribution range is characterized by span. Span = (D 90 -D 10 ) / D 50 . A large span indicates a wide particle size distribution, and a small span indicates a narrow particle size distribution;

[0144] Sedimentation resistance performance: Place the silica sols of Examples 1-5 and Comparative Examples 1-6 in a transparent container and leave them at room temperature for three months. Regularly observe whether precipitation occurs and record the time (days) when precipitation appears in the silica sol;

[0145] The silica sol, polyvinylpyrrolidone (PVP), tetramethylammonium hydroxide (TMAH), chelating agent (EDTA), and deionized water of Examples 1-5 and Comparative Examples 1-6 were compounded at a mass ratio of 30:0.5:0.5:0.3:68.7 and stirred evenly. Then, using a UNIPOL-1203 chemical mechanical polishing machine and a synthetic leather polishing pad, chemical mechanical polishing was performed on the silicon wafer, and the polishing pressure was set at 200 kPa, the rotation speed was 60 r / min, and the polishing time was 30 min. Then, the surface roughness Ra of the sapphire substrate was measured to characterize the polishing effect of the silica sol of the present invention.

[0146] The test results are shown in Table 1-2 below:

[0147] Table 1

[0148]

[0149] Table 2

[0150]

[0151] Comparing Examples 1-5 in Table 1 with Comparative Examples 1-6 in Table 2, it can be seen that the high-purity silica sol for chemical mechanical polishing of the present invention, by adding sodium polyacrylate and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane, and at the same time adopting a stepwise temperature increase program during the hydrolysis process of the silica sol, makes the finally obtained high-purity silica sol for chemical mechanical polishing have a better average particle size (70 nm - 80 nm), which is suitable for chemical polishing; a relatively narrow particle size distribution, that is, a relatively small span (≤0.13), indicating that the silica sol obtained in the present invention is not easily agglomerated during the preparation process; a better sedimentation resistance performance (able to withstand a three-month storage stability test without precipitation), indicating that the silica sol of the present invention has the characteristic of not easily sedimenting; after polishing the silicon wafer, the silicon wafer has a lower surface roughness (Ra ≤ 0.11), indicating that the silica sol of the present invention has a better polishing effect on the silicon wafer treatment.

[0152] Comparing Examples 1-5 in Table 1 with Comparative Examples 1-3 in Table 2, it can be seen that sodium polyacrylate and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane play a synergistic effect in the silica sol system, making the finally obtained high-purity silica sol for chemical mechanical polishing have a better particle size range, not easily agglomerated, not easily sedimented, and a better polishing effect. Among them, when the mass ratio of sodium polyacrylate and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane is 1:4, all performances are optimal.

[0153] Comparing Examples 1-5 in Table 1 with Comparative Examples 4-5 in Table 2, it can be seen that when the stepwise temperature increase program is not adopted during the preparation process of the silica sol, when only reacting at 60 °C for 6 h or 80 °C for 6 h, due to the different formation rates of silica particles at different temperatures and different agglomeration trends between particles, the deterioration of various performances compared with the case of adopting the stepwise temperature increase program is brought about.

[0154] Comparing Example 1-5 in Table 1 with Comparative Example 6 in Table 2, it can be seen that when changing the addition sequence of sodium polyacrylate and 1H,1H,2H,2H-perfluorooctyltriethoxysilane during the preparation of silica sol, when 1H,1H,2H,2H-perfluorooctyltriethoxysilane is added first and then sodium polyacrylate, each performance is relatively poor. This may be because due to the differences in chain segment length and steric hindrance between the two, the sequence is related to the properties of the protective layer finally formed on the silica surface.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention rather than to limit them. Although the embodiments of the present invention have been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the embodiments of the present invention can still be modified or equivalently replaced, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-purity silica sol for chemical mechanical polishing, characterized in that: Obtained by reacting the following components in parts by mass: 100 parts of silicone monomer Sodium polyacrylate 1-3 parts 4-15 parts of tridecafluorooctyl triethoxysilane Solvent 100-250 parts Catalyst 0.1-5 parts by mass; The mass ratio of the sodium polyacrylate to tridecafluorooctyl triethoxysilane is 1:(3-5); The preparation method of the high-purity silica sol for chemical mechanical polishing comprises the following preparation steps: (1) Weigh the organosilicon monomer, sodium polyacrylate, tridecafluorooctyl triethoxysilane, solvent and catalyst according to the formula; (2) Add solvent to the container, start stirring, add catalyst to adjust the pH of the system to 9-10, add organosilicon monomer dropwise while stirring, and stir under step temperature program control to carry out hydrolysis and polycondensation reaction for 2-8 hours, then add sodium polyacrylate, stir and react at 95°C for 2-3 hours, then add tridecafluorooctyl triethoxysilane and continue to stir and react at 95°C for 2-3 hours to obtain high-purity silica sol for chemical mechanical polishing; The step temperature program is to react at 60-80°C for 2-3 hours, and then react at 85-90°C for 2-5 hours.

2. The high-purity silica sol for chemical mechanical polishing according to claim 1, characterized in that: The organosilicon monomer is selected from at least one of ethyl orthosilicate, methyltriethoxysilane and dimethyldimethoxysilane; The solvent is a mixture of ethanol and deionized water; The catalyst is an aqueous ammonia solution.

3. The high-purity silica sol for chemical mechanical polishing according to claim 2, characterized in that: The mass ratio of ethanol to deionized water is 1:(1.5-3).

4. The high-purity silica sol for chemical mechanical polishing according to claim 3, characterized in that: The mass ratio of the sodium polyacrylate to tridecafluorooctyl triethoxysilane is 1:4; The mass ratio of ethanol to deionized water is 1:

2.

5. A method for preparing a high-purity silica sol for chemical mechanical polishing according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following preparation steps: (1) Weigh the organosilicon monomer, sodium polyacrylate, tridecafluorooctyl triethoxysilane, solvent and catalyst according to the formula of claim 1; (2) Add solvent to the container, start stirring, add catalyst to adjust the pH of the system to 9-10, add silicone monomer dropwise while stirring, and stir under step temperature control to carry out hydrolysis and polycondensation reaction for 2-8 hours, then add sodium polyacrylate, stir and react at 95°C for 2-3 hours, then add tridecafluorooctyl triethoxysilane and continue to stir and react at 95°C for 2-3 hours, to obtain high-purity silica sol for chemical mechanical polishing.

6. A method for preparing high-purity silica sol for chemical mechanical polishing according to claim 5, characterized in that: The step temperature program is to react at 60-80°C for 2-3 hours, and then react at 85-90°C for 2-5 hours.

7. A chemical mechanical polishing liquid, characterized in that: The chemical mechanical polishing liquid comprises the high-purity silica sol for chemical mechanical polishing as claimed in any one of claims 1 to 4 or the high-purity silica sol prepared by the preparation method of the high-purity silica sol for chemical mechanical polishing as claimed in any one of claims 5 to 6.

8. Use of the high-purity silica sol for chemical mechanical polishing according to any one of claims 1 to 4 or the high-purity silica sol for chemical mechanical polishing prepared by the preparation method according to any one of claims 5 to 6 to improve the polishing effect of chemical mechanical polishing liquid.

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