Cerium oxide polishing solution, preparation method and application thereof

Abstract

This invention belongs to the field of polishing materials, and relates to a cerium oxide polishing slurry, its preparation method, and its application. The preparation method of the cerium oxide polishing slurry includes the following steps: S1: Adding cerium oxide nanoparticles to deionized water to obtain a first solution. S2: Performing ultrasonic dispersion treatment on the first solution to obtain a second solution. S3: Homogenizing the second solution to obtain a third solution. S4: Adjusting the pH of the third solution to obtain the cerium oxide polishing slurry. This invention achieves efficient dispersion under dispersant-free conditions through synergistic physical treatment of ultrasound and homogenization. The resulting polishing slurry contains cerium oxide particles with uniform particle size and low aggregation, exhibiting static suspension stability for more than ten days. Furthermore, because no dispersant is introduced, the polishing slurry prepared by this invention completely avoids the interference of dispersants on the surface activity and chemical reactivity of abrasive particles, ensuring high removal rate, high selectivity, and low defect chemical mechanical polishing performance.

Description

Technical Field

[0001] This invention relates to the field of polishing materials technology, specifically to a cerium oxide polishing slurry, its preparation method, and its application. Background Technology

[0002] As integrated circuit technology nodes continue to advance to 7 nanometers, 5 nanometers, and even more advanced 3 nanometers and below, the requirements for global planarization of the wafer surface in chip manufacturing processes have reached atomic-level precision. Chemical mechanical polishing (CMP), as the only key technology capable of achieving global planarization of the wafer surface, directly determines the surface quality, defect control level, and final chip yield and performance through the performance of its polishing slurry.

[0003] Among numerous polishing abrasives, cerium oxide is highly favored due to its unique chemical-mechanical properties. Cerium oxide exhibits extremely high polishing selectivity and material removal rate against silicon oxides, making it an ideal choice for shallow trench isolation (STI) processes, interlayer dielectric polishing, and fine polishing of silicon wafers. The polishing mechanism of cerium oxide abrasives is generally considered to be a synergistic effect of chemical etching and mechanical removal: the surface of cerium oxide nanoparticles undergoes a hydrolysis reaction with silicon dioxide, forming easily removable Ce-O-Si bonds, thereby achieving efficient and low-damage planarization.

[0004] However, nanoscale cerium oxide particles are prone to agglomeration and sedimentation in the liquid phase, leading to poor dispersion stability of the polishing slurry. This results in increased polishing defects on the wafer surface, decreased uniformity, and reduced process reliability. The inherent high surface energy of cerium oxide nanoparticles and their instability in the polishing slurry system pose significant challenges to their commercial application.

[0005] Existing technologies primarily address these issues by adding dispersants to the polishing slurry. However, while this method can delay particle settling to some extent, it still presents several problems: Firstly, dispersant molecules adsorb onto the surface of cerium oxide abrasive, covering its active sites and hindering direct chemical interaction between cerium oxide and silicon dioxide on the wafer, significantly reducing the polishing rate and material removal rate. Secondly, the introduction of dispersants alters the chemical environment of the polishing slurry, making it more susceptible to interactions with other components such as pH adjusters and thickeners. This leads to exceptionally complex formulation development and optimization processes, making it difficult to simultaneously achieve multiple objectives, including dispersion stability, polishing rate, surface quality, and batch consistency.

[0006] Therefore, there is a need for a method that can improve the dispersion stability of polishing slurry without affecting its polishing performance. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the problem of poor dispersion stability and decreased polishing performance in existing cerium oxide polishing slurries, this invention provides a cerium oxide polishing slurry, its preparation method, and its application.

[0009] (II) Technical Solution

[0010] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] In a first aspect, the present invention provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0012] S1: Cerium oxide nanoparticles are added to deionized water to obtain the first solution;

[0013] S2: The first solution is ultrasonically dispersed to obtain the second solution;

[0014] S3: Homogenize the second solution to obtain the third solution;

[0015] S4: Adjust the pH of the third solution to obtain the cerium oxide polishing solution.

[0016] In the preparation method described above, preferably, in step S1, the cerium oxide nanoparticles are mesoporous cerium oxide nanoparticles.

[0017] In the preparation method described above, preferably, in step S1, the concentration of cerium oxide nanoparticles in the first solution is 0.02-0.5 g / mL.

[0018] In the preparation method described above, preferably, in step S2, the first solution is ultrasonically dispersed using a cell disruptor, wherein the pulse frequency of the cell disruptor is 20-90%.

[0019] In the preparation method described above, preferably, the ultrasonic dispersion treatment time in step S2 is 5-40 min.

[0020] In the preparation method described above, preferably, in step S3, the homogenization pressure of the homogenization process is 5000-30000 psi.

[0021] In the preparation method described above, preferably, the homogenization process in step S3 is performed 1-8 times.

[0022] In the preparation method described above, preferably, in step S4, the third solution is diluted with deionized water, and then the pH of the diluted third solution is adjusted to 3-6 by any one or more of acetic acid, oxalic acid, phosphoric acid, and citric acid.

[0023] Secondly, the present invention provides a cerium oxide polishing slurry prepared by the above preparation method.

[0024] Thirdly, the present invention also provides an application of the above-mentioned cerium oxide polishing slurry in a chemical mechanical polishing process.

[0025] (III) Beneficial Effects

[0026] This invention effectively dissociates the soft agglomeration structure between cerium oxide nanoparticles and optimizes their surface hydration state through synergistic physical treatment of ultrasonic dispersion and homogenization, thereby significantly improving the initial dispersion uniformity of cerium oxide nano-abrasives in a pure water system without adding any dispersant.

[0027] In the polishing liquid prepared by this invention, cerium oxide particles maintain a narrow distribution and low aggregation state, exhibiting excellent suspension stability. Under static conditions, they can maintain uniform dispersion for more than ten days, completely avoiding the sedimentation and stratification problems caused by traditional dispersant dependence.

[0028] Furthermore, since the preparation method of the present invention does not introduce any dispersant chemical components throughout the process, it avoids the occupation and shielding of the active sites on the surface of cerium oxide by the dispersant, thereby fully preserving the inherent chemical mechanical properties of the polishing slurry and ensuring that it still has high material removal rate, good selectivity and excellent surface quality control capabilities in actual CMP processes. Attached Figure Description

[0029] Figure 1 This is a comparison graph showing the changes in cerium oxide polishing slurry prepared in Example 1 and Comparative Example 1 over time.

[0030] Figure 2 TEM image of cerium oxide nanoparticles in the cerium oxide polishing solution prepared in Example 1;

[0031] Figure 3 Two-dimensional AFM morphology image of the surface of a silicon oxide wafer after polishing with the polishing slurry prepared in Example 1;

[0032] Figure 4 The image shows the three-dimensional AFM morphology of the silicon oxide wafer surface after polishing with the polishing slurry prepared in Example 1. Detailed Implementation

[0033] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] This invention provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0035] S1: Cerium oxide nanoparticles are added to deionized water to obtain the first solution.

[0036] S2: The first solution is ultrasonically dispersed to obtain the second solution.

[0037] S3: Homogenize the second solution to obtain the third solution.

[0038] S4: Adjust the pH of the third solution to obtain the cerium oxide polishing solution.

[0039] This invention effectively dissociates the soft aggregate structure between cerium oxide nanoparticles and optimizes their surface hydration state through a synergistic physical treatment of ultrasonic dispersion and homogenization. This significantly improves the initial dispersion uniformity of cerium oxide nanoparticles in a pure water system without adding any dispersant. Based on the above-mentioned synergistic treatment of ultrasonic dispersion and homogenization, the polishing slurry prepared by this invention maintains a narrow distribution and low aggregation state of cerium oxide particles, exhibiting excellent suspension stability. Under static conditions, it can maintain uniform dispersion for more than ten days, completely avoiding the sedimentation and stratification problems caused by traditional dispersant dependence.

[0040] Furthermore, since the preparation method of the present invention does not introduce any dispersant chemical components throughout the process, it avoids the occupation and shielding of the active sites on the surface of cerium oxide by the dispersant, thereby fully preserving the inherent chemical mechanical properties of the polishing slurry and ensuring that it still has high material removal rate, good selectivity and excellent surface quality control capabilities in actual CMP processes.

[0041] Preferably, in step S1 above, the cerium oxide nanoparticles selected can be mesoporous cerium oxide nanoparticles. In the obtained first solution, the concentration of cerium oxide nanoparticles is preferably 0.02-0.5 g / mL, more preferably 0.2 g / mL.

[0042] Mesoporous cerium oxide nanoparticles possess a high specific surface area, which is beneficial for water molecule adsorption and interfacial reactions. Furthermore, the homogenization process employed in this invention does not damage the structure of the mesoporous cerium oxide nanoparticles. In this invention, high-pressure homogenization primarily achieves dispersion through liquid-phase shearing and microjets, with gentle and instantaneous forces that do not cause mesoporous wall collapse. In contrast, high-speed shearing or ball milling, or other strong mechanical force treatments reported in existing technologies, easily cause irreversible collapse of the mesoporous structure, leading to a sharp drop in specific surface area and loss of activity. Therefore, this invention, by controlling the upper limit of homogenization pressure and time, precisely avoids the risk of mesoporous damage while fully depolymerizing, thus preserving the intact mesoporous structure.

[0043] Preferably, in step S2 above, the first solution can be ultrasonically dispersed using a cell disruptor, wherein the pulse frequency of the cell disruptor is 20-90%, more preferably 75%.

[0044] Since the cell disruptor has a limited capacity to process the polishing slurry, its processing efficiency may be affected. Therefore, this invention prepares the first solution as a high-concentration cerium oxide polishing slurry stock solution to improve cell disruption efficiency. The cell disruptor can pre-disperse severely agglomerated cerium oxide nanoparticles through ultrasonic action, ensuring a uniform particle size distribution of the cerium oxide nanoparticles in the polishing slurry system. If the cell disruptor's operating pulse is too small, it cannot break up the agglomeration of cerium oxide nanoparticles, failing to achieve the desired disruption effect. Conversely, if the operating pulse is too large, the large amount of heat released will cause significant evaporation of moisture.

[0045] Preferably, in step S2 above, the ultrasonic dispersion treatment time is 5-40 minutes. In step S3, the homogenization treatment is performed 1-8 times. If the ultrasonic treatment is too short, it will lead to insufficient dispersion and the presence of large agglomerates. If the treatment time is too long, it may cause excessive cavitation or shearing, resulting in particle breakage or increased surface defects, which will reduce chemical activity. Therefore, the treatment time of the present invention can ensure complete dissociation of agglomerates while avoiding unnecessary energy consumption and structural damage.

[0046] Preferably, in step S3 above, homogenization can be performed using a homogenizer. The homogenizer further disperses the cerium oxide nanoparticles with a relatively uniform particle size distribution through high-pressure collision, effectively improving the dispersion ability of the cerium oxide nanoparticles and thus enhancing their suspension stability. Further, the homogenization pressure is 5000-30000 psi, more preferably 30000 psi.

[0047] Preferably, in step S4 above, the third solution can be diluted with deionized water to a concentration of 0.001-0.005 g / mL, and then the pH of the diluted third solution can be adjusted to 3-6 using any one or more of acetic acid, oxalic acid, phosphoric acid, and citric acid. A weakly acidic environment can maintain appropriate protonation on the cerium oxide surface, enhancing its electrostatic attraction and coordination ability with deprotonated silanol groups on the SiO2 surface, promoting Ce-O-Si bond formation, while also inhibiting the tendency of cerium oxide to hydrolyze and aggregate under near-neutral conditions. When pH < 3, the acidity is too high, which may lead to excessive corrosion of SiO2 and cause pitting. When pH > 6, the interfacial reaction kinetics decrease, which may lead to a reduction in material removal rate.

[0048] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0049] Example 1

[0050] This embodiment provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0051] S1: Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.2 g / mL.

[0052] S2: The first solution is ultrasonically dispersed for 15 minutes using a cell disruptor to obtain the second solution. In this step, the pulse frequency of the cell disruptor is 75%.

[0053] S3: The second solution is homogenized three times using a homogenizer to obtain the third solution. In this step, the homogenization pressure is 30,000 psi.

[0054] S4: Dilute the third solution to 0.002 g / mL with deionized water, and then adjust the pH of the diluted third solution to 4.0 with acetic acid to obtain the cerium oxide polishing solution.

[0055] Example 2

[0056] This embodiment provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0057] S1: Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.02 g / mL.

[0058] S2: The first solution is ultrasonically dispersed for 5 minutes using a cell disruptor to obtain the second solution. In this step, the pulse frequency of the cell disruptor is 20%.

[0059] S3: Homogenize the second solution once using a homogenizer to obtain the third solution. The homogenization pressure in this step is 5000 psi.

[0060] S4: Dilute the third solution to 0.001 g / mL with deionized water, and then adjust the pH of the diluted third solution to 3 with oxalic acid to obtain cerium oxide polishing solution.

[0061] Example 3

[0062] This embodiment provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0063] S1: Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.5 g / mL.

[0064] S2: The first solution is ultrasonically dispersed using a cell disruptor for 40 minutes to obtain the second solution. In this step, the pulse frequency of the cell disruptor is 90%.

[0065] S3: The second solution is homogenized eight times using a homogenizer to obtain the third solution. The homogenization pressure in this step is 20,000 psi.

[0066] S4: Dilute the third solution to 0.005 g / mL with deionized water, and then adjust the pH of the diluted third solution to 6 with phosphoric acid to obtain cerium oxide polishing solution.

[0067] Example 4

[0068] This embodiment provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0069] S1: Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.1 g / mL.

[0070] S2: The first solution is ultrasonically dispersed using a cell disruptor for 20 minutes to obtain the second solution. In this step, the pulse frequency of the cell disruptor is 50%.

[0071] S3: The second solution is homogenized four times using a homogenizer to obtain the third solution. The homogenization pressure in this step is 25000 psi.

[0072] S4: Dilute the third solution to 0.003 g / mL with deionized water, and then adjust the pH of the diluted third solution to 5 with citric acid to obtain cerium oxide polishing solution.

[0073] Example 5

[0074] This embodiment provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0075] S1: Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.3 g / mL.

[0076] S2: The first solution was ultrasonically dispersed for 23 minutes using a cell disruptor to obtain the second solution. In this step, the pulse frequency of the cell disruptor was 39%.

[0077] S3: The second solution is homogenized three times using a homogenizer to obtain the third solution. The homogenization pressure in this step is 22000 psi.

[0078] S4: Dilute the third solution to 0.004 g / mL with deionized water, and then adjust the pH of the diluted third solution to 3.8 with a mixture of acetic acid and oxalic acid to obtain the cerium oxide polishing solution.

[0079] Comparative Example 1

[0080] This comparative example provides a method for preparing a cerium oxide polishing slurry, comprising the following steps:

[0081] Mesoporous cerium oxide nanoparticles were added to deionized water to obtain a first solution with a concentration of 0.8 g / mL. Then, acetic acid was added to the first solution to adjust its pH to 4.0, thus obtaining a cerium oxide polishing solution.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing cerium oxide polishing slurry, which differs from Example 1 in that the homogenization treatment in step S3 is not performed.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing cerium oxide polishing slurry, which differs from Example 1 in that the ultrasonic dispersion treatment in step S2 is not performed.

[0086] Comparative Example 4

[0087] This comparative example provides a method for preparing cerium oxide polishing slurry, which differs from Example 1 in that the order of steps S2 and S3 is replaced.

[0088] The polishing solutions prepared in Example 1 and the comparative example were placed in sample bottles. The two sample bottles were placed together and allowed to stand. The suspension and sedimentation of the polishing solutions in the two sample bottles were observed and photographed to obtain the desired results. Figure 1 .like Figure 1 As shown, the glass sample bottle on the left contains the cerium oxide polishing solution of Comparative Example 1, while the glass sample bottle on the right contains the cerium oxide polishing solution of Example 1. It can be observed that after standing for 5 minutes, the cerium oxide polishing solution of Comparative Example 1 begins to show significant sedimentation, and after standing for 3 hours, it completely settles. In contrast, the cerium oxide polishing solution of Example 1, treated with a cell disruptor and homogenizer, remains stably suspended for more than 3 days, demonstrating a significant improvement in the dispersion effect of the cerium oxide polishing solution.

[0089] After continuous observation, the polishing slurry of Example 1 was able to maintain a stable suspension state for 11 days. In addition, after observation and recording, the polishing slurries prepared in Examples 2-5 were able to maintain a stable suspension state for at least 10 days under static conditions, the polishing slurry prepared in Comparative Example 2 was able to maintain a stable suspension state for about 10 hours under static conditions, the polishing slurry prepared in Comparative Example 3 had severe particle agglomeration and could only maintain its initial state for about 30 minutes under static conditions, and the polishing slurry in Comparative Example 4 also had severe agglomeration and could only maintain its initial state for about 1 hour.

[0090] 40 mL of the polishing solutions prepared in Examples 1-5 and Comparative Examples 1-4 were respectively placed in sample bottles. The average particle size of the cerium oxide nanoparticles in the polishing solutions prepared in Examples 1-5 and Comparative Examples 1-4 was measured using a laser particle size analyzer, and the results are shown in Table 1.

[0091] Table 1. Statistical table of average particle size of abrasives in polishing slurries prepared in Examples 1-5 and Comparative Examples 1-4.

[0092]

[0093] Table 1 shows that after homogenization by the cell disruptor and homogenizer, the average particle size of the cerium oxide nanoparticles did not exceed 160 nm. The average particle size of cerium oxide in Comparative Example 1 was 1963.5 nm, indicating that untreated mesoporous cerium oxide spontaneously formed micron-sized aggregates in pure water. The average particle size of cerium oxide in Comparative Example 2 was 536.4 nm, indicating that ultrasound alone could partially deagglomerate the particles, but could not achieve sufficient homogenization. The average particle size of cerium oxide in Comparative Example 3 was as high as 7360.7 nm, indicating that the cerium oxide nanoparticles, without dispersion by the cell disruptor, were severely agglomerated. During homogenization using the homogenizer, under excessive homogenization pressure, the larger agglomerated cerium oxide nanoparticles further collided with the smaller agglomerated nanoparticles, re-agglomerating into even more severely agglomerated particles, leading to an increase in average particle size. The average particle size of cerium oxide in Comparative Example 4 was 5017.8 nm, which was slightly lower than that in Comparative Example 3, but still reached the micron level. This further illustrates that the process order of ultrasonic dispersion and homogenization is irreplaceable. Only by performing ultrasonic dispersion first and then homogenization can nanoparticles be effectively dispersed.

[0094] The polishing slurry prepared in Example 1 was characterized by TEM, and the results were obtained. Figure 2 .pass Figure 2 It can be seen that after treatment with a cell disruptor and homogenizer, the cerium oxide nanoparticles still maintain a mesoporous spherical morphology and are not damaged by ultrasonic waves and high-pressure impact. In addition, the polishing slurries prepared in Examples 2-5 were also characterized by TEM. The results showed that the cerium oxide nanoparticles in the polishing slurries prepared in Examples 2-5 all maintained a mesoporous spherical morphology and were not damaged by ultrasonic waves and high-pressure impact.

[0095] Polishing tests were conducted on the polishing slurry prepared in Example 1. A POLI-400L (G&P Technology, Inc.) polishing machine was used, paired with a Gas_Pad_16in_GP (KPX Chemical Co., Ltd.) polishing pad. A 4-inch SiO2 wafer with a 1000nm oxide layer thickness was used for polishing. The specific polishing process was as follows: polishing pressure was set to 2.84psi, polishing time with SiO2 wafer polishing slurry was set to 1 min, polishing time with deionized water was set to 20 s, polishing slurry flow rate was 250 mL / min, polishing disc / polishing head rotation speed was 57 / 63 r / min, and disc dressing was performed for 5 min before polishing. After polishing, the wafer was removed, the surface was cleaned with a polyvinyl alcohol brush, rinsed several times with deionized water, and dried with compressed nitrogen. The measured polishing rate was 309.6 nm / min, and the surface roughness of the lens was as follows: Figure 3 as well as Figure 4 As shown, the Ra value of the polished wafer is 0.187 nm after testing.

[0096] Under the same polishing test conditions as in Example 1, parallel polishing tests were conducted on the polishing slurries prepared in Examples 2-5. The material removal rate of Examples 2-5 was consistently between 300-320 nm / min, and the surface Ra value of SiO2 after polishing was between 0.182-0.193 nm.

[0097] Under the same polishing test conditions as in Example 1, parallel polishing tests were continued on the polishing slurries prepared in Comparative Examples 1-4, and the statistical results are as follows:

[0098] Comparative Example 1 showed a material removal rate of 112 nm / min. After polishing, the SiO2 surface exhibited obvious sedimentation particle indentations and random scratches, with an Ra value of 0.89 nm. Comparative Example 2 showed an improved material removal rate of 235 nm / min. The wafer surface showed localized haze areas and a slight orange peel effect, with an Ra value of 0.37 nm. Comparative Example 3, due to severe particle agglomeration, experienced intense scratching during polishing, resulting in an abnormally high removal rate. It was also accompanied by numerous deep scratches and edge peeling, with an Ra value as high as 2.1 nm. Comparative Example 4 showed a material removal rate of 295 nm / min and an Ra value of 1.63 nm. The surface showed obvious linear scratches and uneven corrosion areas.

[0099] The above polishing test results demonstrate that the cerium oxide polishing slurry prepared in this invention has both high material removal rate (RR) and ultra-smooth surface quality (low Ra) under real CMP process conditions. This indicates that the dispersant-free preparation method of this invention does not sacrifice any key polishing performance and successfully solves the contradiction between dispersion stability and polishing performance.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cerium oxide polishing slurry, characterized in that, Includes the following steps: S1: Cerium oxide nanoparticles are added to deionized water to obtain the first solution; S2: The first solution is ultrasonically dispersed to obtain the second solution; S3: Homogenize the second solution to obtain the third solution; S4: Adjust the pH of the third solution to obtain the cerium oxide polishing solution.

2. The preparation method according to claim 1, characterized in that, In step S1, the cerium oxide nanoparticles are mesoporous cerium oxide nanoparticles.

3. The preparation method according to claim 1, characterized in that, In step S1, the concentration of cerium oxide nanoparticles in the first solution is 0.02-0.5 g / mL.

4. The preparation method according to claim 1, characterized in that, In step S2, the first solution is ultrasonically dispersed using a cell disruptor with a pulse frequency of 20-90%.

5. The preparation method according to claim 1, characterized in that, In step S2, the ultrasonic dispersion treatment time is 5-40 min.

6. The preparation method according to claim 1, characterized in that, In step S3, the homogenization pressure during homogenization is 5000-30000 psi.

7. The preparation method according to claim 1, characterized in that, In step S3, the homogenization process is performed 1-8 times.

8. The preparation method according to claim 1, characterized in that, In step S4, the third solution is first diluted with deionized water, and then the pH of the diluted third solution is adjusted to 3-6 using any one or more of acetic acid, oxalic acid, phosphoric acid, and citric acid.

9. A cerium oxide polishing slurry prepared by the preparation method according to any one of claims 1-8.

10. The application of the cerium oxide polishing slurry according to claim 9 in a chemical mechanical polishing process.

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