Preparation method of cerium oxide polishing solution
By preparing a chemical mechanical polishing liquid containing cerium oxide polishing liquid, the trench oxide loss and dish defects caused by the fast SiO2 removal rate in STICMP are solved, and the selective removal of SiO2 and Si3N4 is achieved, which is suitable for integrated circuit manufacturing.
Patent Information
- Application Number
- CN202311831836.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-01
AI Technical Summary
In the prior art, the trench oxide loss and dish defect problems caused by the SiO2 removal rate during the STICMP process, and the removal rate selection ratio of SiO2 and Si3N4 is insufficient, making it difficult to meet the manufacturing needs of high-integrated integrated circuits.
The polishing liquid containing cerium oxide abrasive particles, polishing inhibitors, dispersants, pH adjusters and anionic surfactant is used to control the removal rate of the polishing liquid, slow down the SiO2 removal rate, increase the selection ratio between the silicon oxide film and the silicon nitride film, and reduce the amount of disc traps in the groove part.
The SiO2 removal rate is adjusted, the trench oxide loss is reduced, the disc drop in the 100μm/100μm area is reduced, and the polishing selection ratio between the silicon oxide film and the silicon nitride film is improved. It is suitable for chemical mechanical polishing processes in integrated circuit manufacturing.
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Abstract
Description
Technical Field
[0001] The invention discloses a method for preparing a cerium oxide polishing liquid. Background Art
[0002] With the continuous development of integrated circuit integration, shallow trench isolation (STI) technology has been widely used in the field of integrated circuit manufacturing. The STI structure plays a role in device isolation in high-density transistors, and STI technology has become the mainstream isolation technology in the past decade. Chemical mechanical polishing (CMP), as the only means of global or local flattening in integrated circuit manufacturing, is an important step in the STI structure manufacturing process. In the STI structure manufacturing process, trenches are created on the Si substrate around the active device and filled with SiO2 medium. When filling SiO2, SiO2 will also be deposited in the unnecessary area of the wafer. The excess SiO2 needs to be removed by CMP technology. At the same time, in order to prevent damage to the important epitaxial layer on the Si substrate during the CMP process, it is necessary to grow a Si3N4 stop layer under the SiO2 deposition layer. Therefore, it is very important to reduce the removal rate of Si3N4 as much as possible under the premise of a relatively high SiO2 removal rate. SiO2 sol polishing removes SiO2 medium only by mechanical action, and the removal rate of SiO2 medium is relatively low, resulting in a too low removal rate selection ratio of SiO2 and Si3N4.
[0003] At present, the research on the removal rate selectivity of STICMP mainly focuses on inhibiting the removal rate of Si3N4. The selected additives have little effect on the removal rate of SiO2. However, as the density of integrated circuit transistors gradually increases and the technology nodes continue to advance, STICMP requires minimizing the serious trench oxide loss and dishing defects caused by the excessive removal rate of SiO2. Therefore, the appropriate SiO2 removal rate under the condition of high removal rate selectivity is an urgent problem to be solved. Summary of the invention
[0004] In view of the problems existing in the prior art, in the study of the removal rate selectivity of STICMP, the excessive removal rate of SiO2 by the additive leads to serious groove oxide loss and dishing defects. To this end, the present invention provides a method for preparing a cerium oxide polishing liquid. The product obtained by the method for preparing a cerium oxide polishing liquid of the present invention has one or more of the following advantages: controlling and adjusting the removal rate of the polishing liquid, reducing the loss of groove oxide; slowing down the removal rate of SiO2; being able to reduce the dishing amount of the groove part in the 100μm / 100μm area; or improving the removal selectivity of the polishing liquid to the silicon oxide film RR / silicon nitride film RR.
[0005] The present invention solves the above technical problems through the following technical solutions.
[0006] The present invention provides a cerium oxide polishing liquid, which comprises components in the following mass fractions: 0.1%-10% cerium oxide abrasive particles, 0.1-5% polishing inhibitor, 0.01-5% dispersant, 0.01-2% pH regulator, 50-500 ppm anionic surfactant, and water; the polishing inhibitor is polymethacrylic acid (PMAA); the sum of the mass fractions of each component is 100%, and the mass fraction is the mass percentage of the mass of each component in the total mass of each component.
[0007] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the polymethacrylic acid has a weight average molecular weight of 2000-20000.
[0008] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the cerium oxide abrasive particles are spherical or nearly spherical.
[0009] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the average particle size of the cerium oxide abrasive particles is 50-300 nanometers, preferably 80-180 nanometers, for example, preferably 150 nanometers.
[0010] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the content of the cerium oxide abrasive particles is 4-6%, preferably 5%.
[0011] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the content of the polishing inhibitor is 1%-3%, preferably 1%, 1.5%, 2% or 3%.
[0012] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the dispersant is a common dispersant in the art, preferably one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine or histidine, more preferably glycine or alanine.
[0013] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the content of the dispersant is 0.5%-2%, preferably 0.8%.
[0014] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the pH regulator is an inorganic base or an organic base.
[0015] Among them, the inorganic base is preferably ammonia water. The organic base is preferably a quaternary amine base, more preferably choline.
[0016] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the content of the pH regulator is 0.3%-1%, preferably 0.5% or 0.6%.
[0017] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the anionic surfactant is a carboxylate or a sulfonate.
[0018] Among them, the carboxylates are preferably carboxylates or carboxylic esters and their salts, more preferably fatty alcohol polyether-n carboxylate salts.
[0019] In the cerium oxide polishing liquid, the sulfonates are preferably one or more of alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates or sulfosuccinate esters, more preferably sodium dodecyl benzene sulfonate.
[0020] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the content of the anionic surfactant is 100 ppm - 200 ppm, preferably 150 ppm.
[0021] In a certain embodiment of the present invention, in the cerium oxide polishing liquid, the water is one or more of deionized water, distilled water and ultrapure water, such as deionized water.
[0022] In a certain embodiment of the present invention, the cerium oxide polishing liquid comprises the following components by mass fraction: 4%-6% cerium oxide abrasive particles, 1.5%-3% polymethacrylic acid, 0.7%-0.9% glycine, 0.5%-0.6% pH regulator, 140-160 ppm sodium dodecyl benzene sulfonate, and water;
[0023] The dispersant is glycine and / or alanine; the pH value of the cerium oxide polishing liquid is 6; the pH regulator is ammonia water and / or choline.
[0024] In certain preferred embodiments of the present invention, the cerium oxide polishing liquid comprises the following components:
[0025] (1) 5% cerium oxide abrasive particles, 1% polishing inhibitor, 0.8% dispersant, 0.5% pH regulator, 150 ppm anionic surfactant, and the balance water;
[0026] (2) 5% cerium oxide abrasive particles, 1.5% polishing inhibitor, 0.8% dispersant, 0.5% pH regulator, 150 ppm anionic surfactant, and the balance water;
[0027] (3) 5% cerium oxide abrasive particles, 2% polishing inhibitor, 0.8% dispersant, 0.6% pH regulator, 150 ppm anionic surfactant, and the balance water;
[0028] (4) 5% cerium oxide abrasive particles, 3% polishing inhibitor, 0.8% dispersant, 0.6% pH regulator, 150 ppm anionic surfactant, and the balance water;
[0029] Among (1)-(4) thereof, the cerium oxide abrasive particles, the polishing inhibitor, the dispersant, the pH regulator, the anionic surfactant, and the water are all as described above; the pH of the cerium oxide polishing liquid is 6.
[0030] In a certain embodiment of the present invention, the cerium oxide polishing liquid is composed of the following components by mass fraction: 1%-7% cerium oxide abrasive particles, 0.5-3% polishing inhibitor, 0.05-1% dispersant, 0.05-2% pH regulator, 100-200 ppm anionic surfactant, and the balance water.
[0031] In certain preferred embodiments of the present invention, the cerium oxide polishing liquid is composed of the following components:
[0032] (1) 5% cerium oxide abrasive particles, 1% polymethacrylic acid, 0.8% glycine, 0.5% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0033] (2) 5% cerium oxide abrasive particles, 1.5% polymethacrylic acid, 0.8% glycine, 0.5% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0034] (3) 5% cerium oxide abrasive particles, 2% polymethacrylic acid, 0.8% glycine, 0.6% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0035] (4) 5% cerium oxide abrasive particles, 3% polymethacrylic acid, 0.8% glycine, 0.6% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0036] (5) 5% cerium oxide abrasive particles, 1% polymethacrylic acid, 0.8% alanine, 0.5% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0037] (6) 5% cerium oxide abrasive particles, 1.5% polymethacrylic acid, 0.8% alanine, 0.5% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0038] (7) 5% cerium oxide abrasive particles, 2% polymethacrylic acid, 0.8% alanine, 0.6% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0039] (8) 5% cerium oxide abrasive particles, 3% polymethacrylic acid, 0.8% alanine, 0.6% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water;
[0040] The mass fraction mentioned refers to the percentage of the mass of each component in the total mass of all components; the particle size of the cerium oxide abrasive particles in the cerium oxide polishing liquid is 150 nanometers; the pH of the cerium oxide polishing liquid is 6.
[0041] The present invention also provides a preparation method of the above-mentioned cerium oxide polishing liquid, which includes the following steps: Mixing the components in the cerium oxide polishing liquid to obtain the cerium oxide polishing liquid.
[0042] In a certain embodiment of the present invention, the temperature of the mixing is 20 - 35 °C, for example, 25 °C.
[0043] In a certain embodiment of the present invention, the time of the mixing is 0.5 - 2 h; preferably 1 h.
[0044] In a certain embodiment of the present invention, the pH of the cerium oxide polishing liquid is 4 - 7, preferably 6.
[0045] In a certain embodiment of the present invention, the polishing selectivity ratio of the cerium oxide polishing liquid for the silicon oxide film / silicon nitride film is 25 - 35, preferably 28 - 32; for example, 28.5, 29.7, 31.2, 31.6, 29.3, 30.9, 30.4, 31.5.
[0046] The present invention also provides an application of the above-mentioned cerium oxide polishing liquid in the chemical mechanical polishing process (CMP) in integrated circuit manufacturing.
[0047] Among them, the integrated circuit manufacturing plays an isolation role in high-density transistors through a shallow trench structure; the surface of the integrated circuit manufacturing contains silicon materials, such as SiO2 or SiN;
[0048] Among them, the slurry flow rate of the chemical mechanical polishing process can be the slurry flow rate used in the art, for example, 50 ml / min - 500 ml / min, preferably 200 ml / min; the time of the chemical mechanical polishing process can be 10 s - 5 min (for example, 60 s).
[0049] On the basis of not violating the common knowledge in the art, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.
[0050] The reagents and raw materials used in the present invention are all commercially available. Among them, the spherical cerium oxide grinding particles with a particle size of 150 nm are purchased from Leshan Dongcheng New Materials Co., Ltd.; polymethacrylic acid is purchased from Aladdin Reagent (Shanghai) Co., Ltd.
[0051] The positive and progressive effects of the present invention are as follows: The polishing liquid prepared by the preparation method of the present invention has at least one or more of the following advantages: It can control and adjust the removal rate of the polishing liquid, reduce the loss of trench oxides; slow down the removal rate of SiO2, and can reduce the dishing amount of the trench part in the 100 μm / 100 μm area relative to the silicon nitride film, and can selectively remove the silicon oxide film, having good application prospects. Specific embodiments
[0052] I. Preparation of Preparation Examples 1-8 and Preparation Comparative Examples 1-4
[0053] Preparation of the polishing liquid
[0054] Raw materials: Spherical cerium oxide grinding particles with a particle size of 150 nm, polishing inhibitor, dispersant, pH regulator, anionic surfactant, and water.
[0055] At 25°C, water, spherical cerium oxide grinding particles with a particle size of 150 nm, polishing inhibitor, dispersant, and anionic surfactant are sequentially added to a container and mixed. Subsequently, the pH value is adjusted with a pH regulator, and then mechanically stirred for 1 hour until evenly mixed to obtain a cerium oxide polishing liquid.
[0056] Table 1 Types of each component of the polishing agent
[0057] Example Abrasive particles Polishing inhibitor Dispersant pH regulator Anionic surfactant Water Example 1 Cerium oxide Polymethacrylic acid Glycine Ammonia water Sodium dodecylbenzenesulfonate Deionized water Example 2 Cerium oxide Polymethacrylic acid Glycine Ammonia water Sodium dodecylbenzenesulfonate Deionized water Example 3 Cerium oxide Polymethacrylic acid Glycine Ammonia water Sodium dodecylbenzenesulfonate Deionized water Example 4 Cerium oxide Polymethacrylic acid Glycine Ammonia water Sodium dodecylbenzenesulfonate Deionized water Example 5 Cerium oxide Polymethacrylic acid Alanine Choline Sodium dodecylbenzenesulfonate Deionized water Example 6 Cerium oxide Polymethacrylic acid Alanine Choline Sodium dodecylbenzenesulfonate Deionized water Example 7 Cerium oxide Polymethacrylic acid Alanine Choline Sodium dodecylbenzenesulfonate Deionized water Example 8 Cerium oxide Polymethacrylic acid Alanine Choline Sodium dodecylbenzenesulfonate Deionized water Comparative example 1 Cerium oxide Polymethacrylic acid Glycine Choline Sodium dodecylbenzenesulfonate Deionized water Comparative example 2 Cerium oxide Polymethacrylic acid Alanine Ammonia water Sodium dodecylbenzenesulfonate Deionized water Comparative example 3 Cerium oxide - Glycine Choline Sodium dodecylbenzenesulfonate Deionized water Comparative example 4 Cerium oxide - Alanine Ammonia water Sodium dodecylbenzenesulfonate Deionized water
[0058] Table 2 Mass percentages of each component of the polishing agent
[0059]
[0060]
[0061] The "balance" in the table is, for each example, 100% minus the mass percentage of other components.
[0062] II. Polishing effect experiment
[0063] The polishing conditions are as follows
[0064] 1. Polishing device: AP-300 (CTS)
[0065] 2. Pad: Dow Chemical IC1010
[0066] 3. Polishing time: 60 s
[0067] 4. Polishing temperature: room temperature, 25 °C
[0068] 5. Platen speed: 110 rpm
[0069] 6. Spindle speed: 108 rpm
[0070] 7. Wafer pressure: 3.5 psi
[0071] 8. Slurry flow rate: 200 ml / min
[0072] 9. Wafers: PE-TEOS (thickness 6KA); silicon nitride wafer (thickness 6KA); patterned wafer (15KA) Surface roughness Ra (nm): Surface roughness.
[0073] Polishing rate (RR) of silicon oxide film: Measured using a Filmetrics F54 film thickness measuring instrument
[0074] Polishing rate of silicon nitride film: Measured using a Filmetrics F54 film thickness measuring instrument
[0075] Selectivity: RR of silicon oxide film / RR of silicon nitride film
[0076] Dishing amount of the trench part in the 100μm / 100μm area: Measured using a stylus profilometer (manufactured by P16KLA-tencor)
[0077] Before each polishing, the polishing pad is trimmed with a diamond dresser for 5 minutes to minimize the polishing error caused by the previous polishing. The polished wafers are rinsed with deionized water and dried with high-purity N2.
[0078] The polishing effects of Examples 1-8 and Comparative Examples 1-4 were tested, and the results are shown in Table 3 below.
[0079] Table 3 Polishing effect of polishing agent
[0080]
[0081] As can be seen from the examples, polymethacrylic acid can inhibit the activity of Ce in cerium oxide particles, has a certain inhibitory effect on the etching rates of silicon oxide and silicon nitride, is easy to control and adjust the removal rate of the polishing liquid, and improves the selectivity. 3+ and improve the selectivity.
[0082] In the comparative example, when the addition amount of the inhibitor is too high, such as higher than 5%, the polishing rate of the silicon oxide film will be significantly reduced, affecting the production efficiency; if the inhibitor is not added, the etching rates of both the silicon oxide and the silicon nitride are relatively fast, and the selectivity is about 12 at this time, resulting in an excessive removal amount of the silicon nitride after polishing.
Claims
1. A preparation method of a cerium oxide polishing liquid, characterized in that, It includes the following steps: Mix the following components to obtain a cerium oxide polishing liquid; the cerium oxide polishing liquid includes the following components by mass fraction: 0.1%-10% cerium oxide abrasive particles, 0.1-5% polishing inhibitor, 0.01-5% dispersant, 0.01-2% pH regulator, 50-500 ppm anionic surfactant, and water, and the sum of the mass fractions of each component is 100%; Wherein the polishing inhibitor is polymethacrylic acid.
2. The preparation method of the cerium oxide polishing liquid according to claim 1, characterized in that, The temperature of the mixing is 20-35°C, such as 25°C; And / or, the mixing time is 0.5-2 h; preferably 1 h; And / or, the pH of the cerium oxide polishing liquid is 4-7, preferably 6.
3. The preparation method of the cerium oxide polishing liquid according to claim 1, wherein, The weight-average molecular weight of the polymethacrylic acid is 2000-20000; And / or, the cerium oxide abrasive particles are spherical or nearly spherical; And / or, the average particle size of the cerium oxide abrasive particles is 50-300 nanometers; And / or, the dispersant is one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine or histidine; And / or, the pH regulator is an inorganic base or an organic base; And / or, the anionic surfactant is a carboxylate or a sulfonate; And / or, the water is one or more of deionized water, distilled water and ultrapure water.
4. The preparation method of the cerium oxide polishing liquid according to claim 3, wherein, In the cerium oxide polishing liquid, the average particle size of the cerium oxide abrasive particles is 80-180 nanometers; And / or, in the cerium oxide polishing liquid, the dispersant is glycine or alanine; And / or, in the cerium oxide polishing liquid, the inorganic base is ammonia water; And / or, in the cerium oxide polishing liquid, the organic base is quaternary amine base; And / or, in the cerium oxide polishing liquid, the carboxylates are carboxylates or carboxylate esters and salts; And / or, in the cerium oxide polishing liquid, the sulfonates are one or more of alkyl sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates or sulfosuccinate esters; And / or, in the cerium oxide polishing liquid, the water is deionized water.
5. The preparation method of the cerium oxide polishing liquid according to claim 4, wherein In the cerium oxide polishing liquid, the average particle size of the cerium oxide abrasive particles is 150 nanometers; And / or, in the cerium oxide polishing liquid, the organic base is choline; And / or, in the cerium oxide polishing liquid, the carboxylates are fatty alcohol polyether-n carboxylate salts; And / or, in the cerium oxide polishing liquid, the sulfonates are sodium dodecylbenzenesulfonate.
6. The preparation method of the cerium oxide polishing liquid according to claim 1, characterized in that, In the cerium oxide polishing liquid, the content of the cerium oxide abrasive particles is 4-6%, preferably 5%; And / or, in the cerium oxide polishing liquid, the content of the polishing inhibitor is 1%-3%, preferably 1%, 1.5%, 2% or 3%; And / or, in the cerium oxide polishing liquid, the content of the dispersant is 0.5%-2%, preferably 0.8%; And / or, in the cerium oxide polishing liquid, the content of the pH regulator is 0.3%-1%, preferably 0.5%-0.6%; And / or, in the cerium oxide polishing liquid, the content of the anionic surfactant is 100 ppm-200 ppm, preferably 150 ppm.
7. The preparation method of the cerium oxide polishing liquid according to claim 1, wherein The cerium oxide polishing liquid comprises the following components in mass fractions: 4%-6% cerium oxide abrasive particles, 1.5%-3% polymethacrylic acid, 0.7%-0.9% glycine, 0.5%-0.6% pH regulator, 140 ppm-160 ppm sodium dodecylbenzenesulfonate, and water; The dispersant is glycine and / or alanine; the pH value of the cerium oxide polishing liquid is 6; the pH regulator is ammonia water and / or choline.
8. The preparation method of the cerium oxide polishing liquid according to any one of claims 1-5, characterized in that, The cerium oxide polishing liquid comprises any one of the following components: (1) 5% cerium oxide abrasive particles, 1% polishing inhibitor, 0.8% dispersant, 0.5% pH regulator, 150 ppm anionic surfactant, and the balance water; (2) 5% cerium oxide abrasive particles, 1.5% polishing inhibitor, 0.8% dispersant, 0.5% pH regulator, 150 ppm anionic surfactant, and the balance water; (3) 5% cerium oxide abrasive particles, 2% polishing inhibitor, 0.8% dispersant, 0.6% pH regulator, 150 ppm anionic surfactant, and the balance water; (4) 5% cerium oxide abrasive particles, 3% polishing inhibitor, 0.8% dispersant, 0.6% pH regulator, 150 ppm anionic surfactant, and the balance water; In (1)-(4) thereof, the cerium oxide abrasive particles, the polishing inhibitor, the dispersant, the pH regulator, the anionic surfactant, and the water are all as described in any one of claims 1-5; the pH of the cerium oxide polishing liquid is 6.
9. The preparation method of the cerium oxide polishing liquid according to any one of claims 1-5, characterized in that, The cerium oxide polishing liquid is composed of the following components in mass fractions: 1%-7% cerium oxide abrasive particles as described in any one of claims 1-5, 0.5%-3% polishing inhibitor as described in any one of claims 1-5, 0.05%-1% dispersant as described in any one of claims 1-5, 0.05%-2% pH regulator as described in any one of claims 1-5, 100 ppm-200 ppm anionic surfactant as described in any one of claims 1-5, and the balance water.
10. The preparation method of the cerium oxide polishing liquid according to claim 1, characterized in that, The cerium oxide polishing liquid is composed of any one of the following components: (1) 5% cerium oxide abrasive particles, 1% polymethacrylic acid, 0.8% glycine, 0.5% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (2) 5% cerium oxide abrasive particles, 1.5% polymethacrylic acid, 0.8% glycine, 0.5% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (3) 5% cerium oxide abrasive particles, 2% polymethacrylic acid, 0.8% glycine, 0.6% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (4) 5% cerium oxide abrasive particles, 3% polymethacrylic acid, 0.8% glycine, 0.6% ammonia water, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (5) 5% cerium oxide abrasive particles, 1% polymethacrylic acid, 0.8% alanine, 0.5% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (6) 5% cerium oxide abrasive particles, 1.5% polymethacrylic acid, 0.8% alanine, 0.5% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (7) 5% cerium oxide abrasive particles, 2% polymethacrylic acid, 0.8% alanine, 0.6% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; (8) 5% cerium oxide abrasive particles, 3% polymethacrylic acid, 0.8% alanine, 0.6% choline, 150 ppm sodium dodecylbenzenesulfonate, and the balance deionized water; Wherein, the mass fraction is the percentage of the mass of each component in the total mass of all components; the particle size of the cerium oxide abrasive particles in the cerium oxide polishing liquid is 150 nanometers; the pH of the cerium oxide polishing liquid is 6.