Cerium oxide powder, preparation method and chemical mechanical polishing solution

Abstract

The invention discloses cerium oxide powder, a preparation method and a chemical mechanical polishing solution. The invention provides a preparation method of cerium oxide powder, which comprises the following steps: S1, forming a mixed solution of a cerium chloride solution and an ammonium salt solution under an air condition; and S2, in an inert gas atmosphere, continuously dropwise adding an ammonium salt solution into the mixed solution, and after dropwise adding, carrying out heating reaction, filtering and drying to obtain the truncated octahedral cerium oxide powder. According to the method, cerium chloride is used as a cerium source, weak base or neutral ammonium salt is used as a precipitator, and the cerium oxide powder in a truncated octahedron shape is prepared in an inert gas atmosphere. The truncated octahedral cerium oxide powder has the advantages of uniform particle size distribution, large particle size and high product purity, and the prepared polishing solution has excellent silicon dioxide removal rate and high selection ratio of silicon dioxide to silicon nitride.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials. More specifically, the present invention relates to a cerium oxide powder, a preparation method thereof, and a chemical mechanical polishing liquid. Background Art

[0002] Generally, high-purity silica abrasives are used in the planarization process of semiconductors. In recent years, high-purity cerium oxide abrasives have been more frequently used in the planarization process. The advantage of applying cerium oxide is that a higher processing speed can be obtained compared to applying silica abrasives, and a wider range of additives can be used to prepare stable polishing slurries.

[0003] Cerium dioxide (CeO2) is an inexpensive and widely used rare earth compound with N-type semiconductor properties and a unique 4f electron structure, showing excellent oxygen storage and release capacity and charge exchange capacity, and is widely used in fields such as three-way catalysts, fuel cells, photocatalysis, wastewater and waste gas treatment, polishing materials, and electronic ceramics.

[0004] At present, there are many methods for preparing nano-cerium oxide, including solid-phase method, liquid-phase method, and gas-phase method; the solid-phase reaction method is a method of directly preparing or obtaining nano-CeO2 by re-grinding after fully mixing cerium salts or cerium oxides in a certain proportion, grinding, and then calcining through solid-phase reactions; the liquid-phase method mainly includes precipitation method, sol-gel method, microemulsion method, etc., among which the precipitation method is the most common method in the liquid-phase method, and nano-particles are prepared by controlling various conditions of chemical reactions, such as temperature, concentration, hydrolysis temperature, co-precipitation, etc.; the gas-phase method, also known as chemical vapor deposition method, refers to the process in which two or more simple substances or compounds undergo chemical reactions in the gas phase to form new nano-scale compounds.

[0005] However, the solid-phase method, liquid-phase method, and gas-phase method all have problems such as serious particle agglomeration, uneven particle size distribution, poor monodispersity, and unstable performance, which will seriously affect the use performance of CeO2 functional materials. Therefore, how to improve the particle size of CeO2 and obtain nano-CeO2 with uniform particle size distribution and good dispersibility is a difficult point that needs to be focused on in current preparation research. Summary of the Invention

[0006] An object of the present invention is to solve at least the above problems and provide at least the advantages described hereinafter.

[0007] Another object of the present invention is to provide a method for preparing cerium oxide powder and its application. In the present invention, cerium chloride is used as the cerium source, and a weak base or a neutral ammonium salt is used as the precipitating agent to obtain cerium oxide powder in the shape of truncated octahedron under an inert gas atmosphere. The cerium oxide powder in the shape of truncated octahedron has a uniform particle size distribution, a relatively large particle size and high product purity. The prepared polishing liquid has excellent silicon dioxide removal rate and high selectivity ratio of silicon dioxide to silicon nitride.

[0008] To achieve these objects and other advantages according to the present invention, a method for preparing cerium oxide powder is provided, which comprises the following steps:

[0009] S1. Under air conditions, a mixed solution of a cerium chloride solution and an ammonium salt solution is formed;

[0010] S2. Under an inert gas atmosphere, the ammonium salt solution is continuously added dropwise to the mixed solution. After the dropwise addition is completed, the temperature is raised for reaction, followed by filtration and drying to obtain cerium oxide powder in the shape of truncated octahedron;

[0011] The ammonium salt solution is one or more of an aqueous ammonium acetate solution, an aqueous ammonium bicarbonate solution, and an aqueous ammonium carbonate solution.

[0012] Preferably, in step S1, the molar ratio of cerium chloride in the cerium chloride solution to the ammonium salt in the ammonium salt solution is 1:0.8 - 1.2; in step S2, the molar ratio of cerium chloride in the cerium chloride solution to the ammonium salt in the ammonium salt solution is 1:4 - 6.

[0013] Preferably, the concentration of the ammonium salt is 0.2 - 0.8 mol / L.

[0014] Preferably, the particle size of the cerium oxide powder is 100 - 140 nm.

[0015] Preferably, in step S2, the dropping rate is 3 - 5 mL / min, and the dropping temperature is 20 - 30 °C.

[0016] Preferably, in step S2, the heating rate is 1 - 3 °C / min, and the temperature is raised to 70 - 90 °C, followed by holding the temperature for reaction for 8 - 12 h.

[0017] Preferably, the concentration of the cerium chloride solution is 0.05 - 0.2 mol / L.

[0018] Preferably, in step S2, the drying temperature is 60 - 80 °C, and the drying time is 8 - 12 h.

[0019] In the second aspect of the present invention, a cerium oxide powder is provided, which is prepared by the preparation method described above.

[0020] Preferably, the PDI coefficient of the cerium oxide powder is between 0.1 and 0.2.

[0021] The third aspect of the present invention provides a chemical mechanical polishing liquid, comprising the cerium oxide powder prepared by the preparation method described above.

[0022] The present invention at least includes the following beneficial effects:

[0023] Through research, the present invention finds that using cerium chloride as the cerium source can prepare cerium oxide powder with a regular truncated octahedron structure under mild conditions, which has high purity, low impurity content, and high-purity truncated octahedron cerium oxide powder can be obtained without calcination during the preparation process. The polishing liquid prepared from this cerium oxide powder has excellent silicon dioxide removal rate and high selectivity between silicon dioxide and silicon nitride.

[0024] Other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. Description of the Drawings

[0025] Figure 1 SEM diagram of the cerium oxide powder prepared in Example 1 of the present invention;

[0026] Figure 2 SEM diagram of the cerium oxide powder prepared in Example 2 of the present invention;

[0027] Figure 3 SEM diagram of the cerium oxide powder prepared in Example 3 of the present invention;

[0028] Figure 4 SEM diagram of the cerium oxide powder prepared in Comparative Example 1 of the present invention. Detailed Embodiments

[0029] The first aspect of the present invention provides a preparation method of cerium oxide powder, comprising the following steps:

[0030] S1. Under air conditions, form a mixed solution of a cerium chloride solution and an ammonium salt solution;

[0031] In an embodiment of the present invention, a cerium chloride solution is mixed with an ammonium salt solution to obtain octahedron-shaped cerium oxide powder without the need for calcination. If other cerium salt solutions other than cerium chloride are mixed with the ammonium salt solution, two steps of calcination and hydrothermal synthesis are required to obtain octahedron-shaped cerium oxide powder. The present invention uses cerium chloride as the cerium source for preparing cerium oxide powder, and octahedron-shaped cerium oxide powder can be obtained under mild reaction conditions. Cerium chloride in the present invention forms precipitates such as cerium hydroxide and cerium carbonate under neutral or weakly alkaline conditions, and in an air environment, some precipitates will be oxidized to form cerium oxide precipitates.

[0032] In an embodiment of the present invention, the molar ratio of cerium chloride in the cerium chloride solution to the ammonium salt in the ammonium salt solution in step S1 is 1:0.8 to 1.2. Mixing the ammonium salt solution and the cerium chloride solution can first react to form a cerium oxide crystal nucleus solution with a certain particle size, making the particle size of the formed cerium oxide powder more uniform.

[0033] In an embodiment of the present invention, the concentration of the cerium chloride solution is 0.05 to 0.2 mol / L. It should be noted that the cerium chloride solution is an aqueous solution of cerium chloride, and the ammonium salt solution is an aqueous solution of ammonium salt. When the concentration of the cerium chloride solution is higher than 0.2 mol / L, agglomeration is likely to occur during the preparation of cerium oxide powder; when the concentration of the cerium chloride solution is lower than 0.05 mol / L, due to the low content of cerium oxide in the solution, the particle size and morphology of the cerium oxide powder do not meet the requirements, and regular octahedron-shaped cerium oxide powder cannot be obtained.

[0034] In an embodiment of the present invention, the ammonium salt solution is one or more of an ammonium acetate aqueous solution, an ammonium bicarbonate aqueous solution, and an ammonium carbonate aqueous solution. The ammonium salt can only be a weak acid ammonium salt that is neutral or weakly alkaline, which can enable the regular growth of the later cerium oxide powder. Strong acid ammonium salts cannot react with cerium chloride under the mild conditions of this experiment, and regular growth of cerium oxide powder cannot be obtained. The concentration of the ammonium salt affects the regular growth of octahedron-shaped cerium oxide powder. The concentration of the ammonium salt solution cannot be too high or too low. When the concentration of the ammonium salt solution is 0.2 to 0.8 mol / L, octahedron-shaped cerium oxide powder can be stably grown.

[0035] S2. Under an inert gas atmosphere, continue to dropwise add the ammonium salt solution to the mixed solution, heat up and react after dropping, filter, and dry to obtain octahedron-shaped cerium oxide powder.

[0036] It should be noted that before dropping the ammonium salt solution, it is necessary to bubble inert gas into the mixed solution formed in step S1 to exhaust the air in the mixed solution and the container where the mixed solution is located.

[0037] In an embodiment of the present invention, the inert gas can be nitrogen or helium.

[0038] In an embodiment of the present invention, the molar ratio of cerium chloride in the cerium chloride solution to the ammonium salt in the ammonium salt solution in step S2 is 1:4 to 6; controlling the molar ratio of the ammonium salt solution to the cerium chloride solution within this range is conducive to the stable and regular growth of cerium oxide powder into truncated octahedrons.

[0039] In an embodiment of the present invention, the dropping rate in step S2 is 3 to 5 mL / min. Controlling the dropping rate can enable the cerium chloride solution to stably and regularly grow into cerium oxide powder with an octahedral structure.

[0040] In an embodiment of the present invention, the dropping temperature in step S2 is 20 to 30 °C. The temperature during the dropping process cannot be too high. When the temperature is higher than 30 °C, the aggregation rate will become faster at the initial stage of crystal nucleus formation, which is not conducive to controlling the regular growth and particle size range of the truncated octahedron cerium oxide powder in the later stage.

[0041] In an embodiment of the present invention, the heating rate in step S2 is 1 to 3 °C / min, heating to 70 to 90 °C, and holding for 8 to 12 h. If the heating rate is higher than 3 °C / min, the heating speed is too fast, which is not conducive to the growth of the regular octahedral crystal form. The holding reaction mainly promotes the growth and formation of the octahedral crystal form of the cerium oxide powder.

[0042] In an embodiment of the present invention, the drying temperature in step S2 is 60 to 80 °C, and the drying time is 8 to 12 h.

[0043] In an embodiment of the present invention, steps S1 and S2 are preferably carried out under weakly alkaline conditions, and the weakly alkaline environment of steps S1 and S2 is provided by the ammonium salt solution.

[0044] The second aspect of the present invention provides a cerium oxide powder. In an embodiment of the present invention, the DLS particle size of the cerium oxide powder prepared by the present invention is 100 to 140 nm, preferably, the DLS particle size of the cerium oxide powder is 110 to 120 nm, the PDI coefficient of the cerium oxide powder is between 0.1 and 0.2, and the particle size of the cerium oxide powder prepared by the present invention is between 60 and 160 nm. The polishing liquid prepared from the cerium oxide powder of the present invention has excellent silica removal rate and high selectivity ratio of silica to silicon nitride.

[0045] The cerium oxide powder prepared by the present invention has uniform particle size, no obvious agglomeration, and clear particle boundaries under the electron microscope. The cerium oxide powder prepared by the present invention has high purity and low impurity content.

[0046] The third aspect of the present invention provides a chemical mechanical polishing liquid, which includes the cerium oxide powder prepared by the above preparation method, a lubricant, a complexing agent, a water-soluble polymer, a pH regulator, and a dispersant.

[0047] In an embodiment of the present invention, based on the total weight of the polishing liquid, the polishing liquid may include 0.5 to 10 wt% of the cerium oxide powder provided by the second aspect of the present invention, preferably 0.5 to 8 wt%; more preferably 0.5 to 6 wt%; still more preferably 0.5 to 4 wt%. Specifically, the cerium oxide powder may account for 0.50 wt%, 0.55 wt%, 0.60 wt%, 0.65 wt%, 0.70 wt%, 0.75 wt%, 0.80 wt%, 0.85 wt%, 0.90 wt%, 0.95 wt%, 1.00 wt%, 1.05 wt%, 1.10 wt%, 1.15 wt%, 1.20 wt%, 1.25 wt%, 1.30 wt%, 1.35 wt%, 1.40 wt%, 1.45 wt%, 1.50 wt%, 1.55 wt%, 1.60 wt%, 1.65 wt%, 1.70 wt%, 1.75 wt%, 1.80 wt%, 1.85 wt%, 1.90 wt%, 1.95 wt%, 2.0 wt% of the total mass of the polishing liquid.

[0048] In an embodiment of the present invention, the lubricant includes at least one of ethylene glycol, diethylene glycol, glycerol, polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, xylitol, and sorbitol. Based on the total weight of the polishing liquid, the lubricant may include at least 0.03 wt%, and the lubricant may include at most 0.06 wt%. Specifically, the lubricant may account for 0.03 wt%, 0.035 wt%, 0.04 wt%, 0.045 wt%, 0.05 wt%, 0.055 wt%, 0.06 wt% of the total mass of the polishing liquid.

[0049] In an embodiment of the present invention, the complexing agent includes at least one of monocarboxylic acid, dicarboxylic acid, polycarboxylic acid, phosphonic acid, sulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprene sulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycolic acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid, maleic acid, phthalic acid, cystine, threonine, aspartic acid, glutamic acid, histidine, lysine, serine, methionine, tyrosine, proline, phenylalanine, cystine, hydroxyproline, and tryptophan. Based on the total weight of the polishing liquid, the complexing agent may include at least 0.005 wt%, and the complexing agent may include at most 0.007 wt%. Specifically, the complexing agent may account for 0.005 wt%, 0.006 wt%, 0.007 wt% of the total mass of the polishing liquid.

[0050] In an embodiment of the present invention, the water-soluble polymer compound is selected from at least one of polyacrylic acid or its salts, polymethacrylic acid or its salts, polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. Based on the total weight of the polishing liquid, the water-soluble polymer compound may include at least 0.1 wt%, and may include at most 0.3 wt%. Specifically, the water-soluble polymer compound may account for 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, 0.20 wt%, 0.21 wt%, 0.22 wt%, 0.23 wt%, 0.24 wt%, 0.25 wt%, 0.26 wt%, 0.27 wt%, 0.28 wt%, 0.29 wt%, or 0.30 wt% of the total mass of the polishing liquid.

[0051] In an embodiment of the present invention, the pH regulator is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, ammonium hydroxide, and ammonia water. The concentration of the pH regulator is not limited, and a relatively low concentration is appropriate. The pH regulator adjusts the pH of the polishing liquid within the range of 4 to 8.

[0052] In an embodiment of the present invention, the dispersant is selected from at least one of sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, alkylaryl phosphate, alkylbenzene sulfonate, dialkyl sulfosuccinate, trimethyl stearamide chloride, polyoxyethylene alkylphenol ether, and sorbitol. Based on the total weight of the polishing liquid, the dispersant may include at least 0.05 wt%, and may include at most 0.2 wt%. Specifically, the dispersant may account for 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.10 wt%, 0.11 wt%, 0.12 wt%, 0.13 wt%, 0.14 wt%, 0.15 wt%, 0.16 wt%, 0.17 wt%, 0.18 wt%, 0.19 wt%, or 0.20 wt% of the total mass of the polishing liquid.

[0053] In an embodiment of the present invention, the polishing liquid of the present invention includes 0.5 to 10 wt% of the cerium oxide powder provided in the second aspect of the present invention, 0.04 to 0.06 wt% of a lubricant, 0.005 to 0.007 wt% of a complexing agent, 0.1 to 0.3 wt% of a water-soluble polymer compound, 0.05 to 0.2 wt% of a dispersant, and the pH is between 4 and 8.

[0054] The following further elaborates on the present invention in conjunction with embodiments, so that those skilled in the art can implement it with reference to the text of the specification.

[0055] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation examples are all conventional methods, and the reagents and materials, unless otherwise specified, can all be obtained from commercial channels.

[0056] <Example 1>

[0057] Take 250 mL of 0.05 mol / L cerium chloride aqueous solution and 25 mL of 0.4 mol / L ammonium acetate aqueous solution, mix and stir for 0.5 h, and continue to stir while bubbling with nitrogen for 1 h.

[0058] Under a nitrogen atmosphere, add 150 mL of 0.4 mol / L ammonium acetate aqueous solution dropwise to the cerium chloride aqueous solution at a rate of 3 mL / min. After the addition is complete, heat the mixture to 80 °C at a rate of 2 °C / min and keep it at 80 °C for 8 h.

[0059] After the reaction is completed, centrifuge, wash with water, filter, and dry at 80 °C for 12 h to obtain truncated octahedron nano-ceria powder. For its SEM image, see Figure 1 。

[0060] <Example 2>

[0061] Take 250 mL of 0.05 mol / L cerium chloride aqueous solution and 25 mL of 0.6 mol / L ammonium acetate aqueous solution, mix and stir for 0.5 h, and continue to stir while bubbling with nitrogen for 1 h.

[0062] Under a nitrogen atmosphere, add 120 mL of 0.6 mol / L ammonium acetate aqueous solution dropwise to the cerium chloride aqueous solution at a rate of 4 mL / min. After the addition is complete, heat the mixture to 80 °C at a rate of 1 °C / min and keep it at 80 °C for 12 h.

[0063] After the reaction is completed, centrifuge, wash with water, filter, and dry at 80 °C for 12 h to obtain truncated octahedron nano-ceria powder. For its SEM image, see Figure 2 。

[0064] <Example 3>

[0065] Separate and prepare 250 mL of 0.05 mol / L cerium chloride aqueous solution and 25 mL of 0.5 mol / L ammonium acetate aqueous solution, mix and stir for 0.5 h, and continue to stir while bubbling with nitrogen for 1 h.

[0066] Under a nitrogen atmosphere, add 150 mL of 0.5 mol / L ammonium acetate aqueous solution dropwise to the cerium chloride aqueous solution at a rate of 5 mL / min. After the addition is complete, heat the mixture to 70 °C at a rate of 1 °C / min and keep it at 70 °C for 12 h.

[0067] After the reaction is completed, centrifuge, wash with water, filter, and dry at 80 °C for 12 h. Truncated octahedron nano-ceria powder is obtained. For its SEM image, seeFigure 3 .

[0068] <Example 4>

[0069] Prepare 125 mL of 0.1 mol / L cerium chloride aqueous solution and 25 mL of 0.5 mol / L ammonium acetate aqueous solution respectively, mix and stir for 0.5 h, and continue to stir while bubbling with nitrogen for 1 h.

[0070] Under a nitrogen atmosphere, add 150 mL of 0.5 mol / L ammonium acetate aqueous solution dropwise to the cerium chloride aqueous solution at a rate of 5 mL / min. After the addition is complete, heat it to 70 °C at a rate of 1.5 °C / min, and keep it at 70 °C for 12 h.

[0071] After the reaction is completed, centrifuge, wash with water and filter, and dry at 80 °C for 12 h. Octahedral nanocrystalline cerium oxide powder with truncated corners is obtained. For its SEM image, see Figure 3 .

[0072] <Example 5>

[0073] Prepare 125 mL of 0.08 mol / L cerium chloride aqueous solution and 25 mL of 0.4 mol / L ammonium acetate aqueous solution respectively, mix and stir for 0.5 h, and continue to stir while bubbling with nitrogen for 1 h.

[0074] Under a nitrogen atmosphere, add 140 mL of 0.4 mol / L ammonium acetate aqueous solution dropwise to the cerium chloride aqueous solution at a rate of 4 mL / min. After the addition is complete, heat it to 70 °C at a rate of 2 °C / min, and keep it at 70 °C for 12 h.

[0075] After the reaction is completed, centrifuge, wash with water and filter, and dry at 80 °C for 12 h. Octahedral nanocrystalline cerium oxide powder with truncated corners is obtained.

[0076] <Comparative Example 1>

[0077] The preparation method of Comparative Example 1 is the same as that of Example 1, except that 0.05 mol / L cerium nitrate aqueous solution is used instead of 0.05 mol / L cerium chloride aqueous solution. The SEM image of the prepared cerium oxide powder is as shown in Figure 4 .

[0078] <Comparative Example 2>

[0079] The preparation method of Comparative Example 2 is the same as that of Example 1, except that 0.05 mol / L cerium sulfate aqueous solution is used instead of 0.05 mol / L cerium chloride aqueous solution.

[0080] <Comparative Example 3>

[0081] The preparation method of Comparative Example 3 was the same as that of Example 1, except that the 0.4 mol / L ammonium acetate aqueous solution was replaced with a 0.4 mol / L ammonium nitrate aqueous solution.

[0082] <Comparative Example 4>

[0083] Take 250 mL of 0.05 mol / L cerium chloride aqueous solution and 175 mL of 0.4 mol / L ammonium acetate aqueous solution, and respectively bubble with nitrogen for 2 h under vigorous stirring conditions.

[0084] Under a nitrogen atmosphere, 175 mL of 0.4 mol / L ammonium acetate aqueous solution was added dropwise to the cerium chloride aqueous solution at a rate of 3 mL / min. After the addition was completed, the temperature was raised to 80 °C at a rate of 2 °C / min, and after reaching 80 °C, it was kept warm for 8 h.

[0085] After the reaction was completed, it was centrifuged, washed with water, filtered, and dried at 80 °C for 12 h to obtain cerium oxide powder.

[0086] <Comparative Example 5>

[0087] The preparation method of Comparative Example 5 was the same as that of Example 1, except that after the addition was completed, the temperature was raised to 60 °C at a rate of 4 °C / min, and after reaching 60 °C, it was kept warm for 15 h.

[0088] <Performance Test of Cerium Oxide Powder>

[0089] Polishing fluids were prepared, respectively including 1 wt% of the cerium oxide powders prepared in Examples 1-5 and Comparative Examples 1-5, 0.05 wt% of glycerol, 0.006 wt% of gluconic acid, 0.2 wt% of polyacrylic acid, 0.1 wt% of sorbitol, and the balance was water, and the pH was adjusted between 5.0 and 6.0.

[0090] Measurement of the polishing rate of the polishing fluid: The polishing machine was a Japanese Ebara machine, the polished wafer was a silicon wafer loaded with silicon dioxide and silicon nitride, the polishing pad was of the DH5501 model, the polishing fluid was the polishing fluid prepared from the cerium oxide powders of Examples 1-5 and Comparative Examples 1-5 above, the supply flow rate of the polishing fluid was 200 ml / min, the dresser was a diamond disk of 3MA165P, the pressure was 6 lbf, the rotation speed of the polishing disk was 52 rpm, the rotation speed of the polishing head was 53 rpm, and the pressure of the polishing head was 3.5 psi. Under the above test conditions, the test wafer was polished, and the removal rates of silicon dioxide and silicon nitride were calculated from the wear reduction, and the unit was

[0091] Table 1

[0092]

[0093]

[0094] In Examples 1 to 5 of the present invention, cerium oxide powder with an octahedron structure truncated at the corners was prepared. The structures of the cerium oxide powders prepared in Comparative Examples 1 to 5 of the present invention were irregular. The polishing liquid prepared from the cerium oxide powder with an octahedron structure truncated at the corners prepared in Examples 1 to 5 of the present invention has excellent silicon dioxide removal efficiency and a high SiO 2 / Selective removal ratio of SiN.

[0095] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for preparing cerium oxide powder, characterized in that, It includes the following steps: S1. Under air conditions, a mixed solution of cerium chloride solution and ammonium salt solution is formed; S2. Under an inert gas atmosphere, ammonium salt solution is continuously added dropwise to the mixed solution. After the addition is completed, the temperature is raised for reaction, filtered, and dried to obtain octahedral cerium oxide powder with truncated corners; The ammonium salt solution is one or more of ammonium acetate aqueous solution, ammonium bicarbonate aqueous solution, and ammonium carbonate aqueous solution; The heating rate is 1 - 3 °C / min, and the temperature is raised to 70 - 90 °C, and the reaction is kept warm for 8 - 12 h.

2. The method for preparing the cerium oxide powder according to claim 1, characterized in that, In step S1, the molar ratio of cerium chloride in the cerium chloride solution to ammonium salt in the ammonium salt solution is 1:0.8 - 1.2; in step S2, the molar ratio of cerium chloride in the cerium chloride solution to ammonium salt in the ammonium salt solution is 1:4 - 6.

3. The preparation method of the cerium oxide powder according to claim 1, characterized in that, The concentration of the ammonium salt solution is 0.2 - 0.8 mol / L.

4. The preparation method of the cerium oxide powder according to claim 1, characterized in that, The DLS particle size of the cerium oxide powder is 100 - 140 nm.

5. The preparation method of the cerium oxide powder according to claim 1, characterized in that, In step S2, the dropping rate is 3 - 5 mL / min, and the dropping temperature is 20 - 30 °C.

6. The preparation method of the cerium oxide powder as described in claim 1, characterized in that, The concentration of the cerium chloride solution is 0.05 - 0.2 mol / L.

7. The method for preparing cerium oxide powder according to claim 1, wherein, In step S2, the drying temperature is 60 - 80 °C, and the drying time is 8 - 12 h.

8. A cerium oxide powder, characterized in that, Prepared by the preparation method according to any one of claims 1 - 8.

9. The cerium oxide powder according to claim 8, characterized in that, The PDI coefficient of the cerium oxide powder is between 0.1 and 0.

2.

10. A chemical mechanical polishing liquid, comprising the cerium oxide powder according to claim 8 or 9.

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