Chemical mechanical fine polishing liquid and application thereof

Abstract

The invention relates to the technical field of chemical mechanical polishing, and provides chemical mechanical fine polishing liquid as well as a preparation method and application thereof. The ultra-high-purity silica sol polishing solution comprises the following components in percentage by mass: 3%-10% of ultra-high-purity silica sol, 0.1%-0.5% of a pH regulator, 0.3%-1% of a protective agent 1, 0.015%-0.1% of a protective agent 2 and the balance of water, and the ratio of the protective agent 1 to the protective agent 2 is (10-20): 1. Wherein the protective agent 1 is selected from at least one of cellulose, polyvinylpyrrolidone and polyvinyl alcohol; and the protective agent 2 is selected from a low pour point nonionic surfactant or low-foam polyoxyethylene ether. The fine polishing liquid provided by the invention is applied to chemical mechanical polishing of silicon wafers, and can reduce the number of surface defects and haze (Haze).

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical mechanical polishing (CMP), in particular to a chemical mechanical polishing liquid and application thereof. BACKGROUND

[0002] Silicon is the first generation of semiconductor material, which is abundant in reserves and low in cost, and is widely used in integrated circuit and photovoltaic industry. Semiconductor-grade silicon wafer is the cornerstone of integrated circuit manufacturing, and its surface quality is directly related to the performance and yield of chips. It has extremely strict requirements on surface cleanliness, geometric characteristics, physical and chemical properties, etc.

[0003] Surface cleanliness control includes 1) particle contamination: the line width on the chip has entered the nanometer scale, so the size and number of particles are extremely strict. Advanced processes even require detection of 5nm level particles. Particles can cause photolithography defects, short circuits or open circuits. 2) Metal contamination: transition metals (such as Fe, Cu, Ni, Cr, etc.) are "poisons" of silicon materials. They can introduce energy levels in silicon, become charge recombination centers, reduce minority carrier lifetime, increase leakage current, and even destroy the integrity of the gate oxide layer. Its allowable concentration is usually lower than 101 0 atoms / cm2. 3) Organic contaminants: organic molecules from the environment, personnel or process may adhere to the surface of the silicon wafer, causing poor epitaxial growth, poor adhesion of photoresist or generating haze. It usually needs to be removed by strict cleaning process (such as RCA standard cleaning method).

[0004] The "haze" defect on the surface of the semiconductor silicon wafer is a problem that needs to be closely monitored in the manufacturing process. It usually refers to the observable microscopic haze defect or contamination layer on the surface of the silicon wafer. Its performance will directly affect 1) product yield (Yield): Haze defects on the surface of the silicon wafer may cause pattern distortion, missing or bridging in the photolithography process, resulting in chip failure or performance degradation. A small defect can be enough to destroy an expensive chip. For photolithography masks, the Haze defects on them will be copied to every wafer during the exposure process, causing large-area defects, and the loss is particularly severe.

[0005] 2) Process Stability and Consistency: Haze defects can lead to quality differences between different batches of silicon wafers, and even within the same batch, making the manufacturing process unpredictable and unstable, increasing the difficulty and cost of quality control. 3) Challenges of Advanced Processes: As integrated circuit feature sizes continue to shrink (entering the nanometer scale), the requirements for silicon wafer surface quality become extremely stringent. Any tiny haze defect becomes unacceptable. Simultaneously, in pursuit of higher resolution, the wavelengths of light sources used in photolithography are constantly shortening (e.g., from 248nm KrF to 193nm ArF). Higher-energy photons accelerate certain chemical reactions on the silicon wafer and mask surfaces, causing haze defects to grow and manifest more quickly, making the haze problem even more prominent and challenging in advanced processes.

[0006] In integrated circuit manufacturing, chemical mechanical polishing (CMP) is used to process the surface of silicon wafers, achieving global planarization. With the reduction in feature size of integrated circuits and the increase in silicon wafer size, higher requirements are placed on the removal of metallic impurities and particle residues on the surface of silicon wafers after CMP. Fine polishing is the final step in preparing silicon wafers with intact lattices and undamaged surfaces, making it a crucial step in semiconductor device manufacturing technology. After fine polishing and cleaning, the most important indicators are particle residue and haze value. The silicon wafer surface should have fewer than 30 particles larger than 26nm, and the haze value should be between 0.05 and 0.07 ppm. Both performance indicators must be met simultaneously.

[0007] Chinese patent application CN118571747A discloses a method for precisely controlling the haze and oxide film thickness of silicon polished wafers. This method controls the haze value primarily through the cleaning process, specifically the cleaning temperature and time in the SC1 tank. Chinese patent application CN117480230A discloses a final polishing slurry composition for silicon wafers to reduce surface defects and haze, and a final polishing method using the same. This composition includes ultrapure water, polishing particles, a pH adjuster, a water-soluble thickener, and a chelating agent. It must simultaneously include quaternary ammonium salt ions (provided by the pH adjuster) and a methacrylate polymer (provided by the water-soluble thickener), which can reduce surface defects and haze on silicon wafers. Chinese patent application CN114940866A discloses a chemical mechanical polishing solution for silicon wafers. By increasing the viscosity of the polishing solution, a thicker pressure film is formed during polishing, reducing the number of surface defects and roughness of the wafer. Other chemical mechanical polishing solution patents mainly address the reduction of surface defects and do not involve application schemes that improve the haze performance of the polishing solution through formulation. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a chemical mechanical polishing solution that, through a specific formulation of components and the ratio between the components, can achieve a polishing solution with uniform particle size distribution. Furthermore, when this polishing solution is applied to the chemical mechanical polishing of silicon wafers, it can reduce the haze value on the wafer surface.

[0009] Another object of the present invention is to provide the application of the above-mentioned chemimechanical polishing solution.

[0010] To achieve its objective, the present invention provides the following technical solution:

[0011] A chemical mechanical polishing solution, by mass percentage, comprises the following components: 3%–10% ultra-high purity silica sol, 0.1%–0.5% pH adjuster, 0.3%–1% protective agent 1, 0.015%–0.1% protective agent 2, with the balance being water, and the ratio of protective agent 1 to protective agent 2 being 10–20:1;

[0012] Wherein, the protective agent 1 is selected from at least one of cellulose, polyvinylpyrrolidone, and polyvinyl alcohol; the protective agent 2 is selected from low pour point nonionic surfactants or low foaming polyoxyethylene ethers.

[0013] In a preferred embodiment, the composition comprises, by weight percentage: 5%–8% ultra-high purity silica sol, 0.3%–0.5% pH adjuster, and 0.3%–0.6% protective agent 1.

[0014] 0.015% to 0.06% of protectant 2, with the balance being water, and the ratio of protectant 1 to protectant 2 is 10 to 20:1.

[0015] In one specific embodiment, the protective agent 1 is selected from one or more of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinylpyrrolidone K15, K30, K60, K90, and polyvinyl alcohol with a degree of alcoholysis of 40%, 90%, and 99%, preferably polyvinylpyrrolidone K15 or polyvinyl alcohol with a degree of alcoholysis of 90%.

[0016] In one specific embodiment, the protective agent 2 is selected from one or more of the following low-pour-point nonionic surfactants: WANOL SA30, 50, 70, 80, 90; WANOL PA30, 50, 70, 80, 90; and low-foaming polyoxyethylene ethers: WANOL IS1004L, 1005L, 1007L, 1008L, 1009L, preferably WANOL SA50 or WANOL PA50.

[0017] In one specific implementation, the ultra-high purity silica sol has a metal ion content of <400 ppb and a primary particle size of 10–70 nm.

[0018] In one specific embodiment, the pH adjuster is selected from one or more of ammonia, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and piperazine, preferably tetramethylammonium hydroxide.

[0019] In one specific implementation, the method for preparing the chemical mechanical polishing solution includes the following steps:

[0020] 1) The intermediate mixture is subjected to intermediate first-stage filtration and intermediate second-stage filtration in sequence to obtain the intermediate product; the intermediate mixture is a mixture including water, pH adjuster and protective agent, and no ultra-high purity silica sol is added to the intermediate mixture;

[0021] 2) Mix the ultra-high purity silica sol and the intermediate product, and then perform first-stage filtration and second-stage filtration of the polishing solution to obtain the chemimechanical polishing solution.

[0022] In one specific implementation, the filter material of the first-stage filtration of the intermediate product in step 1) is polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), and the filter material of the second-stage filtration is polysulfone (PSF), polyethersulfone (PES), sulfonated polyethersulfone (SPES), or nylon.

[0023] In step 2), the filter element material of the first stage filtration of the polishing solution is polyethylene (PE) or polypropylene (PP), and the filter element material of the second stage filtration is polyethylene (PE) or polypropylene (PP).

[0024] The present invention also provides the application of the chemical mechanical polishing solution described above in the chemical mechanical polishing of wafers, wherein the wafer is preferably a silicon wafer or a wafer with silicon as a substrate.

[0025] In one specific implementation, the conditions for silicon wafer polishing are as follows: polishing machine OKAMOTO PNX332C, silicon wafer diameter 300mm. P1 disk uses medium polishing solution, polishing pad is SUBA series, polishing pressure is 10KPa, polishing temperature is 25~30℃, polishing head and polishing disk rotation speed is 50 / 51rpm, polishing solution flow rate is 1L / min;

[0026] The P2 and P3 discs use a fine polishing solution, a POLYPAS27NX series polishing pad, a polishing pressure of 8 kPa, a polishing temperature of 25–30°C, a polishing head and disc rotation speed of 50 / 51 rpm, and a polishing solution flow rate of 1 L / min.

[0027] The technical solution provided by this invention has the following beneficial effects:

[0028] The chemical mechanical polishing solution of this invention includes a protective agent 1 that can be adsorbed onto the surface of the wafer and ultra-high purity silica sol, removing defects caused by intermediate polishing without creating new scratches. The protective agent 2, with a lower molecular weight than protective agent 1, can be adsorbed onto minute defects on the wafer surface. At specific addition ratios, they work synergistically to increase planarization efficiency, resulting in a smoother wafer surface after repair and reducing the wafer surface haze value. Combined with the preparation method of the chemical mechanical polishing solution of this invention, the number of defects on the wafer surface can be reduced. Attached Figure Description

[0029] Figure 1 The image shown is of Haze after fine polishing with liquid polishing, as shown in Comparative Example 5.

[0030] Figure 2 This is a Haze image after fine polishing with liquid polishing solution in Example 4. Detailed Implementation

[0031] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0033] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] The present invention provides a chemical mechanical polishing solution, comprising, by mass percentage: 3%–10% ultra-high purity silica sol, 0.1%–0.5% pH adjuster, 0.3%–1% protective agent 1, 0.015%–0.1% protective agent 2, with the balance being water, and the ratio of protective agent 1 to protective agent 2 being 10–20:1 (e.g., 10:1, 12:1, 14:1, 16:1, 18:1, 20:1, etc.);

[0035] The protective agent 1 is selected from at least one of cellulose, polyvinylpyrrolidone, and polyvinyl alcohol; for example, it is selected from one or more of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinylpyrrolidone K15, K30, K60, K90, and polyvinyl alcohol with a degree of hydrolysis of 40%, 90%, and 99%, preferably polyvinylpyrrolidone K15 or polyvinyl alcohol with a degree of hydrolysis of 90%; the amount of protective agent 1 added is 0.3% to 1% by mass percentage, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc., preferably 0.3%, 0.4%, 0.5%, and 0.6%.

[0036] The protective agent 2 is selected from low-pour-point nonionic surfactants or low-foaming polyoxyethylene ethers; for example, it is selected from one or more of the following: WANOL SA30, 50, 70, 80, 90, WANOL PA30, 50, 70, 80, 90, and low-foaming polyoxyethylene ethers WANOL IS1004L, 1005L, 1007L, 1008L, 1009L, preferably WANOL SA50 or WANOL PA50. The amount of protective agent 2 added is 0.015% to 0.1% by mass, for example, 0.015%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%.

[0037] The concentrations are 0.07%, 0.08%, 0.09%, 0.1%, etc., preferably 0.015%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%.

[0038] The ultra-high purity silica sol has a metal ion content of <400 ppb and a primary particle size of 10–70 nm, such as 10 nm, 20 nm, 30 nm, 50 nm, or 70 nm. The amount of ultra-high purity silica sol added is 3%–10% by mass, such as 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, preferably 5%, 6%, 7%, or 8%.

[0039] The pH adjuster is selected from one or more of ammonia, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and piperazine, preferably tetramethylammonium hydroxide; the amount of the pH adjuster added is 0.1% to 0.5% by mass percentage, for example 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., preferably 0.3%, 0.4%, or 0.5%.

[0040] The method for preparing the chemical mechanical polishing solution of the present invention includes the following steps:

[0041] 1) The intermediate mixture is subjected to intermediate first-stage filtration and intermediate second-stage filtration in sequence to obtain the intermediate product; the intermediate mixture is a mixture including water, pH adjuster and protective agent, and no ultra-high purity silica sol is added to the intermediate mixture;

[0042] 2) Mix the ultra-high purity silica sol and the intermediate product, and then perform first-stage filtration and second-stage filtration of the polishing solution to obtain the polishing solution.

[0043] In step 1), the filter material of the first stage of filtration of the intermediate product is polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), and the filter material of the second stage of filtration is polysulfone (PSF), polyethersulfone (PES), sulfonated polyethersulfone (SPES) or nylon.

[0044] In step 2), the filter element material of the first stage filtration of the polishing solution is polyethylene (PE) or polypropylene (PP), and the filter element material of the second stage filtration is polyethylene (PE) or polypropylene (PP).

[0045] Specifically, the process conditions for the first-stage filtration and second-stage filtration of the intermediate product, as well as the first-stage filtration and second-stage filtration of the polishing solution, can be referred to in the prior art, such as patent CN118421208B.

[0046] A second aspect of the present invention provides the application of the chemical mechanical polishing solution described above in the chemical mechanical polishing of wafers, wherein the wafer is a silicon wafer or a wafer with silicon as a substrate.

[0047] In some embodiments, the polishing solution is diluted 10-50 times (by mass) with water (preferably ultrapure water) before polishing. In some embodiments, when the polishing solution is used to polish silicon wafers, the polishing conditions are, for example: an OKAMOTO PNX332C polishing machine, a silicon wafer diameter of 300 mm; a medium polishing solution for disk P1, a SUBA series polishing pad, a polishing pressure of 10 kPa, a polishing temperature of 25-30°C, a polishing head and polishing pad rotation speed of 50 / 51 rpm, and a polishing solution flow rate of 1 L / min; for disks P2 and P3, a fine polishing solution, a POLYPAS27NX series polishing pad, a polishing pressure of 8 kPa, a polishing temperature of 25-30°C, a polishing head and polishing pad rotation speed of 50 / 51 rpm, and a polishing solution flow rate of 1 L / min.

[0048] The main raw materials used in the embodiments and comparative examples of this invention are described below:

[0049] Ultra-high purity silica sol: purchased from FUSO Corporation, Japan, with a metal ion content of <400ppb and a primary particle size of 10-70nm;

[0050] Unless otherwise specified, all other reagents are ordinary raw materials purchased from the market;

[0051] Unless otherwise specified, all wafers are Prime wafers purchased from the market.

[0052] Examples 1-9

[0053] A chemical mechanical polishing (CMP) solution for silicon wafers was prepared. The CMP solution comprised, by mass percentage, 3%–10% ultra-high purity silica sol, 0.1%–0.5% pH adjuster, 0.3%–1% protective agent 1, 0.015%–0.1% protective agent 2, and the balance being water. The ratio of protective agent 1 to protective agent 2 was 10–20:1. The components and their mass content in the CMP solutions of each embodiment are shown in Table 1. The preparation process of the CMP solution included the following steps:

[0054] 1) Mix the pH adjuster, protective agent and water evenly to obtain an intermediate mixture. Then, filter the intermediate mixture through the first stage of intermediate filtration and the second stage of intermediate filtration to obtain the intermediate product.

[0055] 2) Add the ultra-high purity silica sol to the intermediate product in step 1), mix evenly, and then subject the resulting mixture to first-stage filtration and second-stage filtration of the polishing solution to obtain the silicon wafer chemical mechanical polishing solution.

[0056] For the specific process conditions of the first-stage filtration and second-stage filtration of the intermediate product, as well as the first-stage filtration and second-stage filtration of the polishing solution, please refer to Example 4 in patent CN118421208B.

[0057] Table 1. Composition of chemical mechanical polishing solution for silicon wafers in Examples 1-9

[0058]

[0059] In Table 1, "content" refers to the percentage of each component based on the total mass of the polishing solution.

[0060] Comparative Example 1

[0061] The process was carried out in accordance with Example 6, except that the intermediate product was not filtered in step 1) and the fine polishing solution was filtered in step 2).

[0062] Comparative Example 2

[0063] The process was carried out in accordance with Example 6, except that the intermediate product was filtered in step 1) and the polishing solution was not filtered in step 2).

[0064] Comparative Example 3

[0065] The process was carried out in accordance with Example 6, except that the intermediate product was not filtered in step 1) and the polishing solution was not filtered in step 2).

[0066] Comparative Example 4

[0067] The procedure was carried out in accordance with Example 6, except that protectant 1 was not added to the formulation, while other operating conditions and parameters remained unchanged.

[0068] Comparative Example 5

[0069] The procedure was carried out in accordance with Example 6, except that protectant 2 was not added to the formulation, while other operating conditions and parameters remained unchanged.

[0070] Comparative Example 6 (the ratio of protective agent 1 to protective agent 2 is 5):

[0071] The procedure was carried out in accordance with Example 6, except that the PA90 content was 2000 ppm.

[0072] Comparative Example 7 (the ratio of protective agent 1 to protective agent 2 was 25):

[0073] The procedure was carried out in accordance with Example 6, except that the PA90 content was 400 ppm.

[0074] Comparative Example 8

[0075] The same procedure was carried out as in Example 6, except that the protective agent in the formulation was replaced with hydroxypropyl starch, which is used in patent CN 114940866A, at an addition amount of 10,000 ppm, and E1006 was added at an addition amount of 625 ppm.

[0076] The silicon wafer chemical mechanical polishing solutions prepared in the above embodiments and comparative examples were used to polish silicon wafers, and their application performance was investigated.

[0077] The silicon wafers used are 300mm in diameter and are of Prime grade.

[0078] The polishing solution should be diluted 30 times (by weight) with ultrapure water before use.

[0079] The polishing conditions are as follows: The polishing machine is an OKAMOTO PNX332C. The P1 disc is a Fujimi 1306, the polishing pad is a SUBA600, the polishing pressure is 10 kPa, the polishing temperature is 25-30℃, the polishing head and disc rotation speed is 50 / 51 rpm, and the polishing fluid flow rate is 1 L / min; the P2 and P3 discs use a fine polishing solution, the polishing pad is a POLYPAS 275NX, the polishing pressure is 8 kPa, the polishing temperature is 25-30℃, the polishing head and disc rotation speed is 50 / 51 rpm, and the polishing fluid flow rate is 1 L / min.

[0080] The number of surface defects and haze values ​​of the polished silicon wafers were statistically analyzed, as shown in Table 2. The methods for detecting the number of surface defects and haze values ​​of the silicon wafers are as follows:

[0081] The number of defects with a size greater than 26nm on the wafer surface and the Haze value were recorded using KLA-SP5. 25 wafers were tested and the average value was taken.

[0082] Table 2. Number of surface defects and Haze values ​​of silicon wafers in each embodiment and comparative example.

[0083]

[0084] Compared to Example 6, Comparative Example 4, without the addition of protective agent 1, showed no protection for the abrasive and wafer, resulting in a significant increase in particle number and haze value. Comparative Example 5, without the addition of protective agent 2, failed to repair minor defects, leading to an increase in particle number and haze value. (Haze Map shown...) Figure 1 , 2 As shown, the increased proportion of white areas and the appearance of fan-shaped patterns are unacceptable. Comparative Examples 6 and 7 adjusted the ratio of protectants 1 and 2. If the ratio is less than 10, protectant 2 is excessive, which can reduce the haze value but increases the particle count. If the ratio is less than 20, protectant 2 is too low, failing to form an effective synergistic effect, resulting in increased particle count and haze. Comparative Example 8 replaced the protectant used in other patents, showing significant performance differences compared to the solution in this patent.

[0085] Compared to Example 6, Comparative Examples 1-3 changed the filtration method. Adding filtration of intermediate products and polishing solution effectively traps large-diameter particles, making the wafer surface easier to clean. If the filtration step is omitted, even if the ratio of protective agent 1 to protective agent 2 meets the requirements, it can only reduce the number of defects on the silicon wafer surface to a certain extent, but cannot meet the customer's needs; the number of defects above 26nm is less than 30.

[0086] In Examples 1-9, the ratio of protective agent 1 to protective agent 2 is 10-20:1. Simultaneously, the intermediate product and the polishing solution are filtered separately, further reducing the number of defects and the haze value on the silicon wafer surface. The principle is that protective agent 1 can adsorb onto the wafer and the surface of the ultra-high purity silica sol, removing defects caused by the intermediate polishing without creating new scratches. Protective agent 2 has a lower molecular weight than protective agent 1 and can adsorb onto tiny defects on the wafer surface. At specific addition ratios, they have a synergistic effect, increasing planarization efficiency and resulting in a smoother wafer surface after repair, thus reducing the haze value on the wafer surface.

[0087] In summary, this invention, through a specific addition ratio of protectant 1 and protectant 2 in the formulation, combined with the filtration method of the intermediate product and the polishing solution, results in a polishing solution that can significantly reduce the number of defects and the haze value on the wafer surface during application. Using the polishing solution of this invention, the number of defects above 26nm on the silicon wafer surface is less than 30, and the haze value is between 0.05 and 0.07 ppm, meeting market demands.

[0088] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A chemical mechanical polishing liquid characterized by comprising: comprises the following components by mass percentage: 3-10% of ultra-high purity silica sol, 0.1-0.5% of pH regulator, 0.3-1% of protective agent 1, 0.015-0.1% of protective agent 2, and the balance being water, and the ratio of protective agent 1 to protective agent 2 is 10-20:1; The protective agent 1 is selected from at least one of cellulose, polyvinylpyrrolidone, and polyvinyl alcohol; and the protective agent 2 is selected from a low-foaming non-ionic surfactant or a low-foaming polyoxyethylene ether.

2. The chemical mechanical polishing liquid according to claim 1, wherein comprises the following components by mass percentage: 3-10% of ultra-high purity silica sol, 0.1-0.5% of pH regulator, 0.3-1% of protective agent 1, 0.015-0.1% of protective agent 2, and the balance being water, and the ratio of protective agent 1 to protective agent 2 is 10-20:1; 3. The chemical mechanical polishing liquid according to claim 1 or 2, wherein The protective agent 1 is selected from at least one of hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinylpyrrolidone K15, K30, K60, K90, polyvinyl alcohol with alcoholysis degree of 40%, 90%, and 99%, and preferably polyvinylpyrrolidone K15 or polyvinyl alcohol with alcoholysis degree of 90%.

4. The chemical mechanical polishing liquid according to claim 1 or 2, wherein The protective agent 2 is selected from at least one of low-foaming non-ionic surfactants WANOL SA30, 50, 70, 80, 90, WANOL PA30, 50, 70, 80, 90, and low-foaming polyoxyethylene ethers WANOL IS1004L, 1005L, 1007L, 1008L, 1009L, and preferably WANOL SA50 or WANOL PA50.

5. The chemical mechanical polishing liquid according to claim 1 or 2, wherein The ultra-high purity silica sol has a metal ion content of <400 ppb and a primary particle size of 10-70 nm.

6. The chemical mechanical polishing liquid according to claim 1 or 2, wherein The pH regulator is selected from at least one of ammonia, potassium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and piperazine, and preferably tetramethylammonium hydroxide.

7. The chemical mechanical polishing liquid according to claim 1, wherein The preparation method of the chemical mechanical polishing solution comprises the following steps: 1) sequentially performing first-stage filtration and second-stage filtration on an intermediate product to obtain the intermediate product, wherein the intermediate product is a mixture of water, a pH regulator, and a protective agent, and no ultra-high purity silica sol is added to the intermediate product; 2) mixing the ultra-high purity silica sol and the intermediate product, and sequentially performing first-stage filtration and second-stage filtration to obtain the chemical mechanical polishing solution.

8. The chemical mechanical polishing liquid according to claim 7, wherein In step 1), the filter core material of the first-stage filtration is polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), and the filter core material of the second-stage filtration is polysulfone (PSF), polyethersulfone (PES), sulfonated polyethersulfone (SPES), or nylon (Nylon). In step 2), the filter core material of the first-stage filtration is polyethylene (PE) or polypropylene (PP), and the filter core material of the second-stage filtration is polyethylene (PE) or polypropylene (PP).

9. The chemical mechanical polishing solution according to any one of claims 1-8 is used in the chemical mechanical polishing of a wafer, and preferably the wafer is a silicon wafer or a wafer with a silicon substrate.

10. The use of the chemical mechanical polishing liquid according to claim 9 in the chemical mechanical polishing of a wafer, characterized in that, The polishing conditions of the silicon wafer are as follows: the polishing machine is OKAMOTO PNX332C, the diameter of the silicon wafer is 300 mm, the P1 disc is a middle polishing liquid, the polishing pad is SUBA series, the polishing pressure is 8-10 KPa, the polishing temperature is 25-30 DEG C, the rotation speed of the polishing head and the polishing disc is 30 / 31-50 / 51 rpm, and the polishing liquid flow rate is 1 L / min; The P2 and P3 discs are fine polishing liquids, the polishing pad is POLYPAS27NX series, the polishing pressure is 8-10 KPa, the polishing temperature is 25-30 DEG C, the rotation speed of the polishing head and the polishing disc is 30 / 31-50 / 51 rpm, and the polishing liquid flow rate is 1 L / min.

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