Highly stable ceria polishing solution based on acetic acid-ammonium acetate buffer system

Abstract

The application discloses a high-stability cerium dioxide polishing liquid based on an acetic acid-ammonium acetate buffer system.The polishing liquid comprises the following components: nanometer cerium dioxide with a concentration of 1.0wt%-3.0wt%; acetic acid with a concentration of 0.1wt%-0.5wt%, ammonium acetate with a concentration of 0.05wt%-0.1wt%, and the rest is water; and the pH value is 3.5-5.0.The dispersion performance, polishing rate and stability of the polishing liquid are obviously improved, and the quality and performance of the polishing liquid are greatly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of polishing liquid, and particularly relates to a high-stability cerium dioxide polishing liquid based on an acetic acid-ammonium acetate buffer system and a preparation method thereof. BACKGROUND

[0002] In recent years, NAND flash memory has shown the prospect of high-density cell integration and has attracted attention as a large-scale storage device. 3D-NAND flash memory has widely replaced 2D-NAND flash memory in application. When the NAND design node is less than 20 nm, two-dimensional NAND flash memory technology encounters two key limitations. Therefore, most NAND chip manufacturers have decided to switch to the next generation of 3D technology. Reports on 3D-NAND chips show that 3D-NAND chips have faster speed and lower power consumption. With the development of NAND technology from 2D to 3D, a new chemical mechanical polishing process needs to be researched to meet the requirements of 3D-NAND, i.e., the uppermost stepped SiO2 dielectric layer has a higher polishing rate. In addition, higher requirements are put forward for the polishing rate stability and uniformity of cerium dioxide polishing liquid in the shallow trench isolation (STI) process.

[0003] At present, for the chemical mechanical polishing of dielectric layers, the commonly used polishing liquids at home and abroad are SiO2 colloid (silica sol) polishing liquid and cerium dioxide polishing liquid. Colloidal SiO2 abrasive is the most commonly used polishing liquid in dielectric material polishing, but for SiO2 dielectric layers, SiO2 polishing liquid is prone to form scratches and butterfly defects during polishing, and mainly polishes through mechanical action without fully utilizing chemical action. Therefore, a nano abrasive with smaller hardness should be used to obtain a polishing liquid with high material removal rate, low scratch and particle residue, good flowability and stability. The Mohs hardness of CeO2 is 6, which can meet the requirements of chemical mechanical polishing compared with SiO2 (Mohs hardness is 7). However, in the aqueous medium, due to the high surface energy of CeO2, particle agglomeration and rapid sedimentation easily occur, causing the instability of the polishing liquid and affecting the final polishing effect.

[0004] Therefore, a suitable dispersant needs to be selected to improve the dispersion performance of CeO2 particles through electrostatic action or steric hindrance. It has been found that using inorganic acid as a pH adjuster and dispersant can obtain a relatively stable polishing liquid, but the CeO2 polishing liquid has a short stable time and still has a sedimentation phenomenon. The dispersion performance of the CeO2 polishing liquid needs to be further improved, and the polishing rate of the SiO2 material is low, which cannot meet the requirements of cerium oxide polishing liquid chemical mechanical polishing.

[0005] For ceria polishing liquid, the particle size is moderate and the dispersion is more stable, the subsequent chemical mechanical polishing effect will be better. Zeta potential is a commonly used parameter to measure the stability of slurry in the field of colloid processing. The larger the absolute value of Zeta potential, the better the stability of the slurry. Among them, only when the absolute value of Zeta potential is greater than 30mV, the polishing liquid basically reaches stability. Xudong et al. (DOI: 10.13290 / j.cnki.bdtjs.2022.02.006) used citric acid as a pH regulator and dispersant, and obtained a Zeta potential of-27mV for the ceria polishing liquid at pH 5, and the ceria polishing liquid remained stable for 24h; but since the absolute value of Zeta potential is less than 30mV, the stability time of CeO2 polishing liquid is still short. Yang Chaoxia et al. (DOI: 10.16533 / J.CNKI.15-1099 / TF.202202015) used nitric acid as a new dispersant, and the polishing rate of SiO2 material was 248.9nm / min under the conditions of 1% abrasive mass fraction and pH 5. The average particle size of the abrasive increased from 230nm to 260nm in 9 days, and ceria gradually agglomerated; due to the large specific surface area and high surface energy of nano-CeO2 particles, they are easy to agglomerate in aqueous solution, and the chemical reaction between the particles and the wafer is not sufficient, which leads to a low polishing rate and a short stability time of the polishing liquid. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a high-stability ceria polishing liquid based on acetic acid-ammonium acetate buffer system to solve the problems existing in the prior art. The polishing liquid uses the components of acetic acid-ammonium acetate buffer solution as a dispersant, and the pH value of the system is 3.5-5.0; under acidic conditions, the carboxylate ions ionized will be adsorbed on the surface of ceria, and the repulsive force between particles is increased by the double-layer effect, and the tendency of particle aggregation is weakened, thereby improving the dispersion performance. The dispersion performance, polishing rate and stability of the polishing liquid are obviously improved, and the quality and performance of the polishing liquid are greatly improved.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is:

[0008] A high-stability ceria polishing liquid based on acetic acid-ammonium acetate buffer system, the polishing liquid comprises the following components: nano-cerium dioxide concentration is 1.0wt%-3.0wt%; acetic acid concentration is 0.1wt%-0.5wt%, ammonium acetate concentration is 0.05wt%-0.1wt%, and the balance is water; the pH value is 3.5-5.0.

[0009] The ceria polishing liquid has a particle size of 50-500nm.

[0010] The pH value is preferably 4.0-4.5.

[0011] The acetic acid-ammonium acetate buffer solution serves as both a dispersant and a pH regulator.

[0012] The polishing liquid preparation method comprises the following steps: adding a first batch of deionized water to the ceria polishing liquid, stirring, then adding an acetic acid-ammonium acetate buffer solution to make the solution reach a target pH value, and finally adding a second batch of deionized water to make up the balance according to a target concentration, and continuing to stir.

[0013] The ceria polishing liquid has a concentration of 5.0wt%-10.0wt%;

[0014] The acetic acid-ammonium acetate buffer solution is prepared from acetic acid (purity 99wt%) and ammonium acetate crystals; in the acetic acid-ammonium acetate buffer solution, the acetic acid concentration is 0.005mol / L-17mol / L, the ammonium acetate concentration is 1.0mol / L-3mol / L, and the pH value is 3.5-5.5.

[0015] The volume ratio of the buffer solution to the polishing liquid is 1:500-1:100.

[0016] The high-stability ceria polishing liquid based on the acetic acid-ammonium acetate buffer solution system is applied to the polishing process of 3D-NAND flash media layers in integrated circuits.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] The application adds an acetic acid-ammonium acetate buffer solution to an acidic ceria polishing liquid to obtain a dispersed and stable ceria polishing liquid. Under acidic conditions, the carboxylate ions ionized from the ceria polishing liquid are adsorbed on the surface of the ceria, the double-layer effect is increased to increase the repulsive force between the particles, and the tendency of the particles to agglomerate is weakened, thereby improving the dispersion performance. When acetic acid is used as a dispersant, the Zeta potential of the abrasive is 46.47mV, and the average particle size is 266.3nm. When the buffer solution is used as a dispersant, the Zeta potential of the abrasive reaches 51.22mV, and the average particle size is reduced to 183.1nm, and the average particle size and Zeta potential change little within a week. In addition, the self-prepared acetic acid-ammonium acetate buffer solution can inhibit the volatilization of acetic acid. After two weeks of volatilization test, the volatilization amount of the acetic acid-ammonium acetate buffer solution is 2ml, and the volatilization amount of acetic acid reaches 5.5ml, and the volatilization amount of the acetic acid-ammonium acetate buffer solution is less than that of acetic acid. In the chemical mechanical polishing process, the pH of the polishing liquid can be kept stable, and the performance of the polishing liquid is further optimized. Finally, the polishing rate of quartz glass reaches 432.89nm / min. Attached Figure Description

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Figure 1 The graph shows the changes in the average particle size and Zeta potential of cerium oxide abrasives over days after the cerium oxide polishing slurry in Examples 1-4 was dispersed with acetic acid dispersant.

[0021] Figure 2 The graph shows the effect of different pH values ​​of the polishing solution on the SiO2 removal rate in Examples 5-9, where acetic acid was used as the dispersant.

[0022] Figure 3 This is a graph showing the changes in the proportion of different ionic forms of acetic acid in aqueous solution as a function of pH in Example 10.

[0023] Figure 4 The graph shows the results of preparing acetic acid-ammonium acetate buffer solutions with different pH values ​​using acetic acid and ammonium acetate at different concentrations in Example 11.

[0024] Figure 5 The graph shows the changes in the average particle size and Zeta potential of cerium oxide abrasive over days after the cerium oxide polishing slurry in Examples 12-15 was dispersed by an acetic acid-ammonium acetate dispersant.

[0025] Figure 6 The graph shows the changes in the volume of acetic acid and acetic acid-ammonium acetate buffer solutions as a function of the number of days of standing in Example 16.

[0026] Figure 7 The graph shows the effect of polishing solution on SiO2 removal rate at 0 days and 7 days in Examples 17-20, using acetic acid and acetic acid-ammonium acetate buffer solution as dispersants, respectively. Detailed Implementation

[0027] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0028] The chemical mechanical polishing (CMP) machine used in this application is a Rui Xuan SSP-500. The process conditions are: polishing slurry flow rate of 100 ml / min, polishing head speed of 50 r / min, polishing disc speed of 50 r / min, and pressure of 4.0 psi. Quartz wafers (SiO2 purity 99%) were selected for CMP polishing. The average particle size and Zeta potential in this application were measured using a Nicomp 380DLS laser nanoparticle size analyzer (USA). (Unless otherwise specified, all concentration percentages in this application are mass percentages.)

[0029] Example 1

[0030] Preparation of 500 g ceria polishing liquid

[0031] Take 100 g of 5% ceria polishing liquid, add 300 g of deionized water, stir evenly, then add a certain amount of acetic acid, adjust the pH of the polishing liquid to 4.0, and finally supplement the balance with deionized water, continue to stir evenly.

[0032] Example 2

[0033] The polishing liquid prepared in Example 1 was tested for the average particle size and Zeta potential of the ceria abrasive at day 1.

[0034] Example 3

[0035] The steps are the same as Example 2, except that the test time of the average particle size and Zeta potential of the ceria abrasive in the polishing liquid is day 3.

[0036] Example 4

[0037] The steps are the same as Example 2, except that the test time of the average particle size and Zeta potential of the ceria abrasive in the polishing liquid is day 7.

[0038] It is concluded that with acetic acid as dispersant, the average particle size of ceria abrasive increases from 266.3 nm to 289.6 nm after one week. The average particle size shows an overall increasing trend. For Zeta potential, the Zeta potential of ceria abrasive is 46.47 mV at day 0, and the average particle size of ceria abrasive is 35.01 mV at day 7. The Zeta potential is greater than 30 mV, and the change range is within 15 mV. It shows that the polishing liquid can basically maintain good dispersion performance at this time.

[0039] Example 5

[0040] Preparation of 500 g ceria polishing liquid

[0041] Take 100 g of 5% ceria polishing liquid, add 300 g of deionized water, stir evenly, then add a certain amount of acetic acid, adjust the pH of the polishing liquid to 3.0, and finally supplement the balance with deionized water, continue to stir evenly.

[0042] Examples 6-9

[0043] The other steps are respectively equivalent to Example 5, except that the pH of the polishing liquid is adjusted to 4.0-7.0.

[0044] The polishing rate of the polishing liquid of Examples 5-9 on a quartz wafer (purity 99.99%) with a diameter of 100 mm and a thickness of 0.7 mm was measured to be 347.75 nm / min / 420.80 nm / min / 400.53 nm / min / 318.97 nm / min / 311.12 nm / min, respectively. As the pH value increased from 3.0 to 7.0, the removal rate of SiO2 showed a trend of first increasing and then decreasing. In particular, at pH = 4.0, the removal rate of SiO2 was the largest, being 420.80 nm / min.

[0045] Example 10

[0046] Figure 3 The results of the change of the proportion of different ion forms of acetic acid in aqueous solution with pH are shown in the figure. The acidity coefficient pKa of acetic acid is 4.76, and the proportion of each of the two existing forms of acetic acid, i.e. acetic acid molecules and acetate ions, in aqueous solution at different pH values can be obtained. At pH = 4.0, it is close to its acidity coefficient pKa, indicating that the degree of dissociation is large at this time.

[0047] Example 11

[0048] An acetic acid-ammonium acetate buffer solution with pH = 4.2 was prepared to adjust the pH of the polishing liquid to 4.0.

[0049] The relationship between pH and pKa used is: pH = pKa + log(c(ammonium acetate) / c(acetic acid)). A method for preparing an acetic acid-ammonium acetate buffer solution for inhibiting the volatilization of acetic acid, comprising the following steps:

[0050] First step

[0051] Calculation: An acetic acid-ammonium acetate buffer solution with pH = 4.2 was prepared. When pH = 4.2, c(acetic acid) / c(ammonium acetate) ≈ 3.63, i.e. c(acetic acid) = 3.63 mol / L and c(ammonium acetate) = 1.0 mol / L. If 100 ml of buffer solution is prepared, then m(acetic acid) = 21.78 g and m(ammonium acetate) = 7.7 g.

[0052] Second step

[0053] A certain amount of deionized water was taken and 7.7 g of ammonium acetate was added and stirred to dissolve.

[0054] Third step

[0055] 21.78 g of acetic acid was added, and deionized water was added to 100 ml.

[0056] When preparing acetic acid-ammonium acetate buffer solutions with other pH values, c(ammonium acetate) was fixed at 1.0 mol / L.

[0057] An acetic acid-ammonium acetate buffer solution with pH = 5.2 is prepared for adjusting the pH of the polishing liquid to 5.0. When pH = 5.2, c(ammonium acetate) / c(acetic acid) ≈ 2.75, i.e., c(ammonium acetate) = 1.0 mol / L and c(acetic acid) = 0.36 mol / L. If 100 ml of the buffer solution is prepared, then m(acetic acid) = 2.16 g and m(ammonium acetate) = 7.7 g. Therefore, a certain amount of deionized water is taken, 7.7 g of ammonium acetate is added, and stirred to dissolve. Then 2.16 g of acetic acid is added, and deionized water is added to 100 ml.

[0058] An acetic acid-ammonium acetate buffer solution with pH = 6.2 is prepared for adjusting the pH of the polishing liquid to 6.0. When pH = 6.2, c(ammonium acetate) / c(acetic acid) ≈ 27.54, i.e., c(ammonium acetate) = 1.0 mol / L and c(acetic acid) = 0.036 mol / L. If 100 ml of the buffer solution is prepared, then m(acetic acid) = 0.21 g and m(ammonium acetate) = 7.7 g. Therefore, a certain amount of deionized water is taken, 7.7 g of ammonium acetate is added, and stirred to dissolve. Then 0.21 g of acetic acid is added, and deionized water is added to 100 ml.

[0059] An acetic acid-ammonium acetate buffer solution with pH = 7.2 is prepared for adjusting the pH of the polishing liquid to 7.0. When pH = 7.2, c(ammonium acetate) / c(acetic acid) ≈ 275.42, i.e., c(ammonium acetate) = 1.0 mol / L and c(acetic acid) = 0.0036 mol / L. If 100 ml of the buffer solution is prepared, then m(acetic acid) = 0.02 g and m(ammonium acetate) = 7.7 g. Therefore, a certain amount of deionized water is taken, 7.7 g of ammonium acetate is added, and stirred to dissolve. Then 0.02 g of acetic acid is added, and deionized water is added to 100 ml.

[0060] In the preparation of the acetic acid-ammonium acetate buffer solution with pH = 3.2, acetic acid is directly used for adjustment because acetic acid is almost not ionized at pH = 3.2.

[0061] Example 12

[0062] Preparation of 500 g of cerium oxide polishing liquid

[0063] 100 g of cerium dioxide polishing liquid with a mass fraction of 5% is taken, 300 g of deionized water is added, and stirred to uniformity. Then the buffer solution with a concentration of 42.2 wt% and pH = 4.2 prepared in Example 11 (the concentration of acetic acid in the buffer solution is 34.5 wt%, and the concentration of ammonium acetate is 7.7 wt%) is added, and the polishing liquid is adjusted to pH = 4.0 (the amount of the buffer solution finally added is 5 ml). Finally, deionized water is added to make up the rest, and continue to stir to uniformity. At 0 day, the average particle size and Zeta potential of the cerium oxide abrasive are tested.

[0064] Example 13

[0065] The average particle size and Zeta potential of cerium oxide abrasive in the polishing solution prepared in Example 12 were tested on the first day.

[0066] Example 14

[0067] The procedure was the same as in Example 13, except that the average particle size and Zeta potential of cerium oxide abrasive in the polishing solution were tested on the third day.

[0068] Example 15

[0069] The procedure was the same as in Example 13, except that the average particle size and Zeta potential of cerium oxide abrasive in the polishing solution were tested on the seventh day.

[0070] It was concluded that, with acetic acid-ammonium acetate buffer solution as dispersant, the average particle size of cerium oxide abrasive increased from 183.1 nm to 201.5 nm after one week. The average particle size was smaller. As for the Zeta potential, the Zeta potential of cerium oxide abrasive was 51.22 mV on the 0th day, and the average particle size of cerium oxide abrasive was 42.19 mV on the 7th day. The Zeta potential was above 40 mV, and the change range was within 10 mV. This indicated that the polishing solution had good dispersion performance at this time, and the polishing solution was more stable than when acetic acid was used as dispersant.

[0071] Example 16

[0072] 10 ml of acetic acid-ammonium acetate buffer solution prepared in Example 11 was taken in a graduated cylinder, and 10 ml of acetic acid was taken in the same graduated cylinder at the same time. The graduated cylinders used were of the same specification. Figure 6 The results of the change in volume of acetic acid-ammonium acetate buffer solution and acetic acid prepared in Example 11 with standing time are shown. After two weeks, the acetic acid-ammonium acetate buffer solution remained 8 ml, while the acetic acid remained only 4.5 ml. The evaporation amount of acetic acid-ammonium acetate buffer solution was less than that of acetic acid.

[0073] Example 17

[0074] Preparation of 1000 g of cerium oxide polishing solution

[0075] 200 g of cerium oxide polishing solution with a mass fraction of 5% was taken, 700 g of deionized water was added, and after stirring uniformly, a certain amount of acetic acid was added, the polishing solution was adjusted to pH = 4.0, and finally the balance was made up with deionized water, and stirring was continued until uniform.

[0076] On the 0th day, 500 g of the polishing liquid was taken to polish a quartz wafer (purity 99.99%) with a diameter of 100 mm and a thickness of 0.7 mm, and it was found that the removal rate of the polishing liquid of Example 17 on the quartz wafer was 420.80 nm / min.

[0077] Example 18

[0078] On the 7th day, the remaining 500 g of the polishing liquid was taken to polish a quartz wafer (purity 99.99%) with a diameter of 100 mm and a thickness of 0.7 mm, and it was found that the removal rate of the polishing liquid of Example 18 on the quartz wafer was 398.27 nm / min.

[0079] Examples 19-20

[0080] The other steps are equivalent to Examples 17-18, respectively, and the difference is that the acetic acid is replaced with an acetic acid-ammonium acetate buffer solution with a pH of 4.2.

[0081] The quartz wafer (purity 99.99%) with a diameter of 100 mm and a thickness of 0.7 mm was polished, and it was found that the removal rate of the polishing liquid of Examples 19-20 on the quartz wafer was 432.89 nm / min and 411.26 nm / min, respectively.

[0082] It is concluded that the polishing liquid prepared with the buffer solution can maintain a stable polishing rate before and after a week. Overall, the removal rate of the polishing liquid with the acetic acid-ammonium acetate buffer solution as the dispersant on SiO2 is higher than that of the polishing liquid with acetic acid as the dispersant. The polishing effect is better.

[0083] In the manufacturing process of 3D-NAND flash memory, SiO2 and Si3N4 layers are stacked, resulting in a large thickness of the uppermost deposited SiO2 dielectric layer. In order to prepare high-performance flash memory devices, high polishing rate is required for the uppermost SiO2 dielectric layer to achieve planarization. The polishing rate of the ceria polishing liquid prepared in the present application on SiO2 has reached more than 430 nm / min, which is suitable for the polishing of the dielectric layer of 3D-NAND flash memory structure.

[0084] Compared with the chemical mechanical polishing of Cu, Co and other metal materials, the chemical properties of SiO2 are not active and difficult to be oxidized, and it is not possible to oxidize the material into a softer intermediate product by adding an oxidizing agent and then removing it. The abrasive concentration, particle size distribution, additives and pH value are key factors affecting the polishing rate of SiO2. Therefore, by adding a buffer solution as a pH adjuster and dispersant, a dispersed and stable ceria polishing liquid is obtained, and the chemical reaction between the abrasive and the quartz wafer is more sufficient, thereby obtaining a high SiO2 polishing rate.

[0085] It can be seen from the above examples that when the acetic acid-ammonium acetate buffer solution is used as the dispersant, the dispersion performance, polishing rate and stability related to important indicators of abrasive performance are all obviously improved. When acetic acid is used as the dispersant, the Zeta potential of the abrasive is 46.47 mV, and the average particle size is 266.3 nm, at this time the polishing rate of the quartz glass is 420.80 nm / min. And after a week, the Zeta potential and the average particle size of the abrasive change greatly, indicating that the polishing liquid can basically maintain good dispersion performance. When the buffer solution is used as the dispersant, the Zeta potential of the abrasive is as high as 51.22 mV, and the average particle size is 183.1 nm, at this time the polishing rate is 432.89 nm / min. After a week, the abrasive still maintains a high Zeta potential, and the average particle size changes little. In summary, compared with the former polishing liquid, the Zeta potential of the latter polishing liquid is higher, the average particle size is smaller, which indicates that the dispersion performance is stronger, the stability time is longer, and at the same time, the polishing rate is also improved.

[0086] The acetic acid-ammonium acetate buffer solution is added to the acidic cerium oxide polishing liquid. Under acidic conditions, the carboxylate ions ionized from the buffer solution will be adsorbed on the surface of the cerium oxide particles to increase the mutual repulsive force between the cerium oxide particles through the double-layer effect, thereby improving the dispersion performance. The ammonium acetate is added to the acetic acid, and the acetic acid-ammonium acetate buffer solution prepared by increasing the concentration of carboxylate ions can inhibit the ionization of acetic acid, thereby inhibiting the volatilization of acetic acid. The performance of the polishing liquid is further optimized, and the rate of silicon dioxide is also improved.

[0087] The above describes the preferred embodiments of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can also be made, which should be considered as the protection scope of the present application.

[0088] The remaining matters of the present application are known technologies.

Claims

1. A high stability ceria polishing liquid based on acetic acid-ammonium acetate buffer system, characterized by The polishing liquid comprises the following components: nanoscale cerium dioxide at a concentration of 1.0wt%-3.0wt%; acetic acid at a concentration of 0.1wt%-0.5wt%, ammonium acetate at a concentration of 0.05wt%-0.1wt%, and the rest being water; and a pH value of 4.0-4.

5. The cerium dioxide polishing liquid has a particle size of 50-500nm. The preparation method of the high-stability cerium dioxide polishing liquid based on an acetic acid-ammonium acetate buffer solution system comprises the following steps: adding a first batch of deionized water to the cerium dioxide polishing liquid, stirring, then adding an acetic acid-ammonium acetate buffer solution to make the solution reach a target pH value, and finally adding a second batch of deionized water to make up the rest of the amount according to a target concentration, and continuing to stir. The cerium dioxide polishing liquid has a concentration of 5.0wt%-10.0wt%. The acetic acid-ammonium acetate buffer solution is prepared from acetic acid and ammonium acetate, and in the buffer solution, the concentration of acetic acid is 0.005mol / L-17mol / L, the concentration of ammonium acetate is 1.0mol / L-3mol / L, and the pH value is 4.0-4.

5.

2. The high stability ceria polishing solution based on acetic acid-ammonium acetate buffer system according to claim 1, characterized in that, In the preparation method, the purity of acetic acid is 99wt%.

3. The high stability ceria polishing solution based on acetic acid-ammonium acetate buffer system according to claim 1, characterized in that, In the preparation method, the amount of the first batch of deionized water is 5-80% of the amount of the two batches of deionized water.

4. The high stability ceria polishing solution based on acetic acid-ammonium acetate buffer system according to claim 1, characterized in that, In the preparation method, the volume ratio of the buffer solution to the polishing liquid is 1:500-1:

100.

5. The application of the high-stability cerium dioxide polishing liquid based on an acetic acid-ammonium acetate buffer solution system according to claim 1, which is applied to the polishing process of 3D-NAND flash media layers in integrated circuits.

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