Preparation method and application of super-small cerium oxide polishing abrasive doped with metal ions

Abstract

The present application relates to a kind of preparation method and application of super-small cerium oxide polishing abrasive doped with metal ions.The preparation method is to use cerium nitrate hexahydrate as precursor, trioctylphosphine oxide as ligand, doped with hydrated metal nitrate, use ethanol as cosolvent, after the foregoing substance is dissolved, add 1-octadecene, obtain mesoporous cerium oxide nanosphere doped with metal by high-temperature thermal decomposition method;Polishing abrasive is obtained by calcination.The present application provides a kind of preparation method of super-small cerium oxide polishing abrasive doped with metal ions, and the cerium oxide nanometer abrasive with uniform morphology, size controllable and other metal ions doped is prepared, and after doping metal ions, the surface activity of cerium oxide is further enhanced, the content of trivalent cerium ion in sample rises to 31.0% after doping Gd, and the polishing liquid prepared by the abrasive does not need to add any dispersing agent, and can achieve a polishing rate of up to 342nm / min at a low solid content.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying ultra-small cerium oxide polishing abrasive doped with metal ions, belonging to the technical field of polishing materials. Background Technology

[0002] Cerium is the most reactive rare earth element among the lanthanides, excluding europium, and is also the most abundant rare earth element in the Earth's crust. Cerium oxide (CeO2), as the most widely used cerium compound, possesses excellent redox properties. The CeO2 unit cell contains cerium ions in both trivalent and tetravalent states, and reversible conversion between these states can be achieved through the generation or elimination of oxygen vacancies. Therefore, it exhibits excellent redox, oxygen transport, oxygen storage, and oxygen release capabilities. The unique properties of cerium oxide endow it with biomedical activities such as antibacterial, anti-inflammatory, antitumor, and enzyme-mimicking properties, making it suitable for the diagnosis and treatment of various diseases. Simultaneously, CeO2 can also serve as a carrier to combine with other active metals, exhibiting unique catalytic properties and finding wide applications in organic synthesis and exhaust gas purification. In addition to its applications in biology and catalysis, CeO2 nanoparticles, due to their high surface reactivity and strong adsorption capacity, can be used as polishing abrasives in chemical mechanical polishing.

[0003] Chemical mechanical polishing (CMP) is an ultra-precision surface finishing technology. Its basic principle involves bringing the material surface into contact with a polishing slurry. The slurry contains active substances that chemically react with the wafer surface, forming a soluble layer. This soluble layer is then removed from the surface using mechanical force. Therefore, CMP combines the chemical corrosion of oxidants with the mechanical abrasive action of nano-abrasives, removing material at the nanoscale and atomic scale to achieve ultra-smooth and ultra-low-damage surfaces. This polishing technology is currently widely used in optical components, computer hard drives, microelectromechanical systems (MEMS), and integrated circuits. In integrated circuit manufacturing, CMP is a key technology that significantly impacts the production capacity and quality of downstream chips. From a current demand perspective, as integrated circuit feature sizes shrink and integration density increases, higher surface flatness is required, thus placing higher demands on polishing technology.

[0004] In polishing processes, abrasives are one of the most crucial components. Currently, a range of abrasives have been developed, including silicon oxide, aluminum oxide, cerium oxide, and various composite materials. However, as the feature sizes of semiconductor technology continue to shrink, polishing processes demand abrasives with high selectivity and low defect levels, while simultaneously ensuring high polishing yields. Cerium oxide (CeO2), as one of the most widely used abrasive particles in CMP polishing slurries, has been extensively applied in traditional dielectric polishing processes for integrated circuits (ICs), such as shallow trench isolation (STI) and interlayer dielectric (ILD) CMP. CeO2 abrasives can remove dielectric materials through the combined effects of mechanical wear and surface chemical reactions. The material removal rate depends not only on the additives in the slurry but also on the pH value of the slurry and the characteristics of the CeO2 particles. Therefore, one way to improve the CMP performance of CeO2 abrasives is to improve the characteristics of the CeO2 abrasive particles. Currently, most cerium oxide polishing abrasives are obtained through calcination, precipitation, and sol-gel methods. However, crystal growth is difficult to control, resulting in abrasives with varying shapes and sizes. Furthermore, preparing spherical abrasives is even more challenging, easily leading to scratches during polishing and significantly impacting the performance of the finished product. Therefore, it is necessary to develop a uniformly sized spherical or near-spherical cerium oxide polishing abrasive to improve the surface quality of the polished product. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the aforementioned problems in the prior art, this invention provides a method for preparing ultra-small cerium oxide polishing abrasives doped with metal ions and their applications.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] A method for preparing ultra-small cerium oxide polishing abrasive doped with metal ions includes the following steps: S1, using cerium nitrate hexahydrate as a precursor, trioctylphosphine oxide as a ligand, doping with hydrated metal nitrate, using ethanol as a co-solvent, the aforementioned substances are mixed and dissolved, and then solvent 1-octadecene is added, and the metal ion-doped mesoporous cerium oxide nanospheres are obtained by high-temperature thermal decomposition.

[0010] S2. Polishing abrasives made of mesoporous cerium oxide nanospheres doped with metal ions can be obtained by calcining the nanospheres.

[0011] In the preparation method described above, preferably, in step S1, the hydrated nitrate oxymetal is any one or more of gadolinium hydrate, zirconium hydrate, neodymium hydrate, ytterbium hydrate, lanthanum hydrate, or yttrium hydrate.

[0012] In the preparation method described above, preferably, in step S1, the molar ratio of cerium nitrate hexahydrate, trioctylphosphine oxide, and hydrated nitrate oxymetal is 17-19:20-30:1-3.

[0013] Extensive experimental research revealed that when the molar ratio of cerium hexahydrate to hydrated metal nitrate is below 19:1, effective doping cannot be achieved, and the effect on increasing the trivalent cerium ion content in the product is not significant. When the ratio is above 17:3, it affects the morphology of the product in this invention, leading to a decrease in the polishing performance of the material. Therefore, the preferred molar ratio of cerium hexahydrate to hydrated metal nitrate is 17–19:1–3.

[0014] In the preparation method described above, preferably, in step S1, the temperature at which the aforementioned substances are mixed and dissolved is 80°C, and the molar ratio of 1-octadecene to cerium nitrate hexahydrate is 40–150:1.

[0015] In the preparation method described above, preferably, in step S1, the high-temperature thermal decomposition method is carried out at 180℃~260℃ for a reaction time of 30~60min.

[0016] In the preparation method described above, preferably, in step S2, the calcination temperature is 480℃~550℃ and the calcination time is 1.5~4h.

[0017] The preparation method described above yields cerium oxide polishing abrasives with uniform morphology and spherical or near-spherical particle sizes ranging from 15 to 30 nm, doped with metal ions.

[0018] The application of the preparation method described above for obtaining ultra-small cerium oxide polishing abrasives doped with metal ions in the preparation of polishing fluids.

[0019] In the application described above, preferably, the mass concentration of the ultra-small cerium oxide polishing abrasive doped with metal ions in the polishing solution is 0.15% to 0.5%, the solvent of the polishing solution is water, and the pH value of the polishing solution is 4 to 5.

[0020] A polishing slurry comprising ultra-small cerium oxide polishing abrasives doped with metal ions, obtained by the preparation method described above.

[0021] Furthermore, the concentration of the ultra-small cerium oxide polishing abrasive in the polishing solution is 0.15% to 0.5% by mass, and the pH value is 4 to 5.

[0022] (III) Beneficial Effects

[0023] The beneficial effects of this invention are:

[0024] This invention provides a method for preparing ultra-small cerium oxide polishing abrasives doped with metal ions. The prepared polishing abrasives are spherical cerium oxide nano-abrasives with uniform morphology, controllable size, and the ability to be doped with other metal ions. The ultra-small cerium oxide doped with metal ions obtained by the method provided by this invention has a high Ce content. 3+ The presence of CeO helps break Si-O bonds during CMP, resulting in a high removal rate of silicon dioxide. Therefore, methods such as reducing particle size and introducing dopants can be used to increase the CeO content in CeO2. 3+ The content helps optimize its polishing performance. Therefore, this invention prepares an ultra-small cerium oxide nano-abrasive with uniform morphology and controllable size, which helps improve the surface quality after CMP. At the same time, the polishing rate is optimized by doping with other metal ions to achieve efficient polishing of integrated circuit chips.

[0025] The ultra-small cerium oxide polishing abrasive doped with metal ions prepared by the preparation method of the present invention further enhances the surface activity of cerium oxide after doping with metal ions. After doping with gadolinium (Gd), the content of trivalent cerium ions in the sample increases to 31.0%. The polishing slurry prepared with this abrasive does not require the addition of any dispersant and can achieve a polishing rate of up to 342 nm / min with a low solid content, resulting in better wafer surface quality after polishing. Attached Figure Description

[0026] Figure 1 The image shows a TEM image of the nano-cerium oxide obtained in Example 1 of this invention.

[0027] Figure 2 The XRD pattern of the nano-cerium oxide prepared in Example 1 of this invention;

[0028] Figure 3 This is a TEM image of commercially available nano-cerium oxide in Comparative Example 2 of this invention;

[0029] Figure 4 The XPS spectrum of the nano-cerium oxide prepared in Example 1 of this invention;

[0030] Figure 5 AFM 3D image of the silicon wafer surface before polishing;

[0031] Figure 6 The image shows the AFM 3D model of the silicon wafer surface obtained after polishing with commercial materials, as shown in Comparative Example 2.

[0032] Figure 7 This is an AFM 3D image of the silicon wafer surface after polishing with the material from Example 1. Detailed Implementation

[0033] The preparation method provided by this invention uses cerium nitrate hexahydrate as a precursor, trioctylphosphine oxide as a ligand, and hydrated metal nitrates as dopants. Mesoporous cerium oxide nanospheres doped with metal ions are obtained by high-temperature thermal decomposition in 1-octadecene using ethanol as a co-solvent. An appropriate concentration of metal ions is beneficial to the surface defects (CeO2) in CeO2. 3+ Enrichment of oxygen vacancies. When impurity ions are introduced into the matrix lattice, its lattice parameters change. The presence of different metal ions in the CeO2 crystal results in the enrichment of some of the bulk Ce. 4+ The substitution of ions by metal ions leads to local lattice expansion in CeO2 crystals, promoting oxygen vacancies and CeO2 formation. 3+ The formation of [a specific chemical structure] enhances the redox ability and surface reactivity of CeO2. In this invention, selecting an appropriate metal ion doping concentration is beneficial for optimizing the performance of CeO2. Too low a concentration of doped metal ions cannot effectively increase the content of trivalent cerium ions, while too high a concentration exceeds the solubility limit of metal ions in cerium oxide crystals and affects the morphology of cerium oxide nanoparticles, which is detrimental to improving polishing performance. Therefore, the preferred addition ratio of cerium hexahydrate to hydrated oxynitrate is 17–19:1–3 by molar ratio.

[0034] 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.

[0035] Example 1

[0036] (1) Using a 100 mL single-necked round-bottom flask as the reaction vessel, add 9.5 mmol of cerium nitrate hexahydrate, 0.5 mmol of gadolinium nitrate hexahydrate, and 12 mmol of trioctylphosphine oxide sequentially. Then add 40 mL of ethanol as a co-solvent and heat the solution to 80 °C to completely dissolve the solid. Add 25 mL of 1-octadecene solution at 80 °C and raise the temperature to 200 °C and react for half an hour. Collect the product by centrifugation, wash several times with ethanol to remove residual reactants, and then dry in an oven at 80 °C overnight.

[0037] (2) The material obtained in step (1) was calcined in air at 1℃ / min to 500℃ for 2 hours using a muffle furnace to obtain yellow mesoporous cerium oxide nanospheres doped with metallic gadolinium.

[0038] (3) Using a transmission electron microscope (TEM, HT7700 Exalens), electron microscope images of the nanomaterials obtained in step (2) were taken, as shown below. Figure 1 As shown, the prepared cerium oxide has a good and uniform mesoporous spherical morphology, and the particle size ranges from 20 to 30 nm.

[0039] (4) The crystal structure of the cerium oxide particles obtained in step (2) was measured by X-ray diffraction spectroscopy (XRD, Bruker), and the data was processed using Jade 6.0 software. Figure 2 The results show that the characteristic peaks of the sample are consistent with those of the cerium oxide standard PDF card, confirming the formation of the cubic fluorite crystal phase in the product.

[0040] Example 2

[0041] (1) Using a 100 mL single-necked round-bottom flask as the reaction vessel, add 9 mmol of cerium nitrate hexahydrate, 1 mmol of gadolinium nitrate hexahydrate, and 12 mmol of trioctylphosphine oxide sequentially. Then add 40 mL of ethanol as a co-solvent and heat the solution to 80 °C to completely dissolve the solid. Add 25 mL of 1-octadecene solution at 80 °C and raise the temperature to 200 °C to react for half an hour. Collect the product by centrifugation, wash several times with ethanol to remove residual reactants, and then dry in an oven at 80 °C overnight.

[0042] (2) The material obtained in step (1) was calcined in air at 1℃ / min to 500℃ for 2 hours using a muffle furnace to obtain yellow mesoporous cerium oxide nanospheres doped with metallic gadolinium. The particle size range of the material was measured to be 20-30 nm using transmission electron microscopy.

[0043] Example 3

[0044] (1) Using a 100 mL single-necked round-bottom flask as the reaction vessel, add 9.5 mmol of cerium nitrate hexahydrate, 0.5 mmol of zirconium nitrate hydrate, and 12 mmol of trioctylphosphine oxide sequentially. Then add 40 mL of ethanol as a co-solvent and heat the solution to 80 °C to completely dissolve the solid. Add 25 mL of 1-octadecene solution at 80 °C and raise the temperature to 200 °C to react for half an hour. Collect the product by centrifugation, wash several times with ethanol to remove residual reactants, and then dry in an oven at 80 °C overnight.

[0045] (2) The material obtained in step (1) was calcined in air at 1℃ / min to 500℃ for 2 hours using a muffle furnace to obtain yellow mesoporous cerium oxide nanospheres doped with metallic zirconium. The particle size range of the material was measured to be 20-30 nm using transmission electron microscopy.

[0046] Example 4

[0047] (1) Using a 100 mL single-necked round-bottom flask as the reaction vessel, add 9 mmol of cerium nitrate hexahydrate, 1 mmol of zirconium nitrate hydrate, and 12 mmol of trioctylphosphine oxide sequentially. Then add 40 mL of ethanol as a co-solvent and heat the solution to 80 °C to completely dissolve the solid. Add 25 mL of 1-octadecene solution at 80 °C and raise the temperature to 200 °C to react for half an hour. Collect the product by centrifugation, wash several times with ethanol to remove residual reactants, and then dry in an oven at 80 °C overnight.

[0048] (2) The material obtained in step (1) was calcined in air at 1℃ / min to 500℃ for 2 hours using a muffle furnace to obtain yellow mesoporous cerium oxide nanospheres doped with metallic zirconium. The particle size range of the material was measured to be 15-20nm using transmission electron microscopy.

[0049] Comparative Example 1

[0050] (1) Using a 100 mL single-necked round-bottom flask as the reaction vessel, add 10 mmol of cerium nitrate hexahydrate and 12 mmol of trioctylphosphine oxide sequentially, followed by 40 mL of ethanol as a co-solvent. Heat the solution to 80 °C to completely dissolve the solid. Add 30 mL of 1-octadecene solution at 80 °C and raise the temperature to 180 °C for half an hour. Collect the product by centrifugation, wash several times with ethanol to remove residual reactants, and then dry in an oven at 80 °C overnight.

[0051] (2) The reactants obtained in step (1) were calcined in air at 1℃ / min to 500℃ for 2 hours using a muffle furnace to obtain yellow mesoporous cerium oxide powder. The particle size range of the material was measured to be 20-30nm using transmission electron microscopy.

[0052] Comparative Example 2

[0053] Commercially available nano-cerium oxide (≥99.5% metals basis, 20-50 nm) was calcined in a muffle furnace in air at a temperature increase of 1 °C / min to 500 °C for 2 hours to obtain a white powder. The electron microscope images obtained using transmission electron microscopy (TEM, HT7700 Exalens) are shown below. Figure 3 As shown, obvious particle agglomeration is visible, with particles of varying sizes and shapes.

[0054] Test Example 1

[0055] The nano-cerium oxide powder prepared in Example 1 was tested using X-ray photoelectron spectroscopy (XPS, AXIS Kratos Supra+), and the obtained data were processed by peak segmentation using Avantage software. Figure 4 The results show that the XPS spectrum of the material identifies 10 deconvolution peaks, among which v0, v′, u′, and u0 peaks correspond to Ce.3+ The features, v, v″, v′, u, u″, u′ correspond to Ce 4+ Ce 3+ The surface concentration is determined by the following equations (1)-(3). In these equations, C and A represent the concentration and area, respectively. Therefore, Ce 3+ The content is calculated as Ce 3+ area and Ce 3+ and Ce 4+ The ratio of the sum of the areas of the two peaks.

[0056] C(Ce 3+ )=A(Ce 3+ ) / [A(Ce 3+ )+A(Ce 4+ (1)

[0057] A(Ce 3+ )=A(v0)+A(v′)+A(u0)+A(u′) (2)

[0058] A(Ce 4+ )=A(v)+A(v″)+A(v″′)+A(u)+A(u″)+A(u″′) (3)

[0059] The same tests were performed on the nano-cerium oxide prepared in Examples 2-4 and Comparative Example 1, and the Ce content in the cerium oxide materials prepared in each example was calculated. 3+ The content is shown in Table 1.

[0060] Table 1. Nano-cerium oxide (Ce) prepared in each example and comparison example. 3+ content

[0061] Serial Number <![CDATA[Ce 3+ Content Example 1 25.7％ Example 2 31.0％ Example 3 23.7％ Example 4 24.2％ Comparative Example 1 21.5％

[0062] As shown in Table 1, after doping with other metal ions, the Ce in nano-cerium oxide... 3+ Increased content enhances surface activity, which is beneficial for improving the CMP performance of cerium oxide.

[0063] Test Example 2

[0064] (1) The nano-cerium oxide powders prepared in Examples 1-4 and Comparative Examples 1-2 were dissolved in deionized water to prepare polishing solutions with a mass concentration of 0.2%. The pH of each polishing solution was adjusted to 4.0 using acetic acid. A GNP POLI-400L polishing machine was used for testing. The polishing head pressure was 3 psi, the turntable speed was 87 rpm, the pressure head speed was 93 rpm, the polishing time was 1 min, and the polishing solution flow rate was 150 mL / min. Polishing tests were performed on 4-inch silicon wafers with an oxide layer thickness of 1000 nm.

[0065] (2) The oxide layer of the silicon wafer before and after polishing was measured using a FilmExpert film thickness measuring instrument (Premier 50). The material removal rate was calculated according to formula (4) based on the change in film thickness before and after polishing. The results are shown in Table 2.

[0066] Material removal rate = (film thickness before polishing (nm) - film thickness after polishing (nm)) / polishing time (min) (4)

[0067] Table 2. CMP removal rates of nano-cerium oxide materials in each embodiment and comparative example.

[0068]

[0069]

[0070] The results above show that, compared to the commercially available cerium oxide material in Comparative Example 2, the spherical mesoporous cerium oxide nanomaterials prepared in this invention can achieve a higher material removal rate. Furthermore, it can be seen that the removal rate of the nano-cerium oxide material after doping with other metal ions is significantly improved, exhibiting excellent polishing performance. Moreover, within a certain range of doped metal ion concentrations, the higher the doping amount, the higher the trivalent cerium ion content. Specifically, the Ce content of the material obtained in Example 4... 3+ The content is higher than that of the material obtained in Example 3, but because the particle size of the material is reduced when it is doped with a higher concentration of zirconium ions, the polishing rate of small particles will decrease, so its material removal rate is lower than that of Example 3.

[0071] Test Example 3

[0072] The surface quality of the silicon wafers before and after polishing was tested using a fast scanning atomic force microscope (AFM, Dimension FastScan Bio), with a scanning area of ​​5×5μm. 2 The AFM 3D image of the silicon wafer surface before polishing is shown below. Figure 5 As shown, the surface before polishing is rough and has significant undulations. Analysis using NanoScope Analysis software yielded an arithmetic mean surface roughness Ra of 0.671 nm. The AFM 3D image of the silicon wafer surface obtained after polishing with commercial materials in Comparative Example 2 is shown below. Figure 6 As shown, the surface quality is improved compared to before polishing, but the roughness is still relatively large, Ra = 0.382 nm. The AFM 3D image of the silicon wafer surface obtained after polishing using the material prepared in Example 1 of this invention is shown below. Figure 7As shown, a flat and smooth surface was produced, and the surface roughness Ra = 0.187 nm was obtained. Compared with commercial materials, the roughness decreased by about 0.2 nm, achieving surface polishing at an atomic scale of less than 0.2 nm. This indicates that CMP using the abrasive prepared in this invention can obtain high surface quality, which provides a better guarantee for the subsequent performance of the product and the product yield.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. Use of a metal ion-doped ultrafine ceria polishing abrasive in the production of a polishing liquid, characterized in that, The doped metal ion super-small cerium oxide polishing abrasive is obtained by the following preparation method: S1, using cerium nitrate hexahydrate as a precursor, trioctylphosphine oxide as a ligand, doping hydrated metal nitrate, using ethanol as a cosolvent, after the foregoing substances are mixed and dissolved, solvent 1-octadecene is added, and doped metal ion mesoporous cerium oxide nanospheres are obtained by high-temperature thermal decomposition; S2, the doped metal ion mesoporous cerium oxide nanospheres are calcined to obtain doped metal ion mesoporous cerium oxide nanosphere polishing abrasive; In step S1, the addition ratio of the cerium nitrate hexahydrate, the trioctylphosphine oxide and the hydrated metal nitrate is 17-19:20-30:1-3 in terms of molar ratio; the high-temperature thermal decomposition is carried out at 180-260 DEG C, and the reaction time is 30-60 min.

2. Use according to claim 1, wherein In step S1, the hydrated metal nitrate is any one or more of gadolinium nitrate hydrate, zirconyl nitrate hydrate, neodymium nitrate hydrate, ytterbium nitrate hydrate, lanthanum nitrate hydrate or yttrium nitrate hydrate.

3. The use according to claim 1, wherein In step S1, the temperature for mixing and dissolving the foregoing substances is 80 DEG C, and the molar ratio of the 1-octadecene to the cerium nitrate hexahydrate is 40-150:

1.

4. The use according to claim 1, wherein In step S2, the calcination temperature is 480-550 DEG C, and the calcination time is 1.5-4 h.

5. The use according to claim 1, wherein The mass concentration of the doped metal ion super-small cerium oxide polishing abrasive in the polishing liquid is 0.15%-0.5%, the solvent of the polishing liquid is water, and the pH value of the polishing liquid is 4-5.

6. A polishing liquid comprising a doped metal ion super-small cerium oxide polishing abrasive, a preparation method of the doped metal ion super-small cerium oxide polishing abrasive comprising the following steps: S1, using cerium nitrate hexahydrate as a precursor, trioctylphosphine oxide as a ligand, doping hydrated metal nitrate, using ethanol as a cosolvent, after the foregoing substances are mixed and dissolved, solvent 1-octadecene is added, and doped metal ion mesoporous cerium oxide nanospheres are obtained by high-temperature thermal decomposition; S2, the doped metal ion mesoporous cerium oxide nanospheres are calcined to obtain doped metal ion mesoporous cerium oxide nanosphere polishing abrasive; in step S1, the addition ratio of the cerium nitrate hexahydrate, the trioctylphosphine oxide and the hydrated metal nitrate is 17-19:20-30:1-3 in terms of molar ratio; the high-temperature thermal decomposition is carried out at 180-260 DEG C, and the reaction time is 30-60 min.

7. The polishing liquid according to claim 6, wherein In step S1, the hydrated metal nitrate is any one or more of gadolinium nitrate hydrate, zirconyl nitrate hydrate, neodymium nitrate hydrate, ytterbium nitrate hydrate, lanthanum nitrate hydrate or yttrium nitrate hydrate.

8. The polishing liquid according to claim 6, wherein In step S1, the temperature for mixing and dissolving the foregoing substances is 80 DEG C, and the molar ratio of the 1-octadecene to the cerium nitrate hexahydrate is 40-150:

1.

9. The polishing liquid according to claim 6, wherein In step S2, the calcination temperature is 480-550 DEG C, and the calcination time is 1.5-4 h.

10. The polishing liquid according to claim 6, wherein The concentration of the super-small cerium oxide polishing abrasive in the polishing liquid is a mass concentration of 0.15%-0.5%, and the pH value is 4-5.

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