Cerium oxide material and preparation method thereof

Abstract

The invention discloses a cerium oxide material and a preparation method thereof.The preparation method comprises the following steps that 1, inorganic ammonium salt is added into a cerium salt aqueous solution under stirring, stirring continues to be conducted for 1-3 h after adding is completed, and a first reactant is obtained; wherein the molar ratio of cerium salt to inorganic ammonium salt in the cerium salt aqueous solution is 1: (4.7-5.3), and the inorganic ammonium salt is ammonium carbonate and / or ammonium bicarbonate; the molar concentration of cerium salt in the cerium salt aqueous solution is 0.08-0.2 mol / L; 2) performing hydrothermal reaction on the first reactant at 180-200 DEG C for 7-24 hours to obtain a second reactant; 3) carrying out solid-liquid separation on the second reactant, washing the separated solid, and drying the washed solid to obtain a precursor; and 4) roasting the precursor at 600-900 DEG C for 2-5 hours to obtain the cerium oxide material. The preparation method can be used for obtaining the cerium oxide material with the particle size of 100-200nm and the general popcorn-shaped morphology.

Description

Technical Field

[0001] The present invention relates to a cerium oxide material and a preparation method thereof. Background Art

[0002] At present, in the fields of semiconductor manufacturing, precision optical device processing, etc., chemical mechanical polishing (CMP) plays a crucial role. Through the synergistic effect of chemical corrosion and mechanical grinding, this technology can effectively remove the surface undulations of materials, achieve nanoscale surface flatness, and provide a high-quality surface foundation for subsequent processes such as chip manufacturing and optical element coating.

[0003] Cerium oxide (CeO 2 )'s unique chemical activity and mechanical properties enable it to chemically react with the surface of the material to be polished during the polishing process, achieving the planarization of the material surface. Factors such as the particle size, morphology, and surface properties of cerium oxide all affect its polishing performance.

[0004] There is a literature report on a cerium dioxide particle and a preparation method thereof. The preparation method includes the following steps: 1) Mix a water-soluble cerium salt and a polyol with a molar ratio of 1:100 - 5000 to obtain a mixed solution; 2) Microwave-treat the mixed solution in a microwave digestion instrument to obtain a precursor reaction solution; wherein, the microwave treatment temperature is 120 - 200 °C and the time is 15 - 60 min; 3) Separate the solid and liquid of the precursor reaction solution, wash and dry the obtained solid to obtain a precursor; 4) Calcinate the precursor to obtain cerium dioxide particles, wherein the cerium dioxide particles are spherical and the particle size D 50 is 100 - 300 nm. Summary of the Invention

[0005] An object of the present invention is to provide a preparation method of a cerium oxide material. The cerium oxide material prepared by this preparation method has a particle size of 100 - 200 nm, and the morphology of the cerium oxide material is generally popcorn-like with good dispersibility. Another object of the present invention is to provide a cerium oxide material prepared according to the above preparation method.

[0006] The present invention adopts the following technical solutions to achieve the above objects.

[0007] On the one hand, the present invention provides a preparation method of a cerium oxide material, including the following steps:

[0008] 1) Under stirring, add an inorganic ammonium salt to an aqueous cerium salt solution. After adding, continue stirring for 1 - 3 h to obtain a first reactant; wherein, the molar ratio of the cerium salt in the aqueous cerium salt solution to the inorganic ammonium salt is 1:4.7 - 5.3, and the inorganic ammonium salt is ammonium carbonate and / or ammonium bicarbonate; the molar concentration of the cerium salt in the aqueous cerium salt solution is 0.08 - 0.2 mol / L;

[0009] 2) Hydrothermally react the first reactant at 180 - 200 °C for 7 - 24 h to obtain the second reactant;

[0010] 3) Separate the solid and liquid of the second reactant, wash the separated solid, and dry the washed solid to obtain the precursor;

[0011] 4) Calcinate the precursor at 600 - 900 °C for 2 - 5 h to obtain the cerium oxide material. In this way, cerium oxide with good dispersibility, a generally popcorn-like morphology, and a particle size of 100 - 200 nm can be obtained.

[0012] No surfactant is added as a dispersant in the present invention. The surfactants mentioned here include, but are not limited to, polyvinylpyrrolidone, polyethylene glycol, cetyltrimethylammonium bromide, sodium dodecyl sulfate, and sodium dodecylbenzenesulfonate, etc. No organic solvent including alcohols is added in the present invention.

[0013] The present invention preferably controls the feeding ratio, feeding method, and reaction temperature of the cerium salt and ammonium salt, thereby facilitating the obtaining of the nano-cerium oxide material with a specific morphology of the present invention.

[0014] In step 1), the inorganic ammonium salt can be added to the cerium salt aqueous solution in batches under stirring, and after the addition, continue stirring for 1 - 3 h to obtain the first reactant. This step can be carried out at room temperature. After adding the inorganic ammonium salt, it is preferably to continue stirring for 1.5 - 2 h. This is more conducive to obtaining the nano-cerium oxide with a generally popcorn-like morphology and good dispersibility of the present invention.

[0015] In the present invention, the molar ratio of the cerium salt to the inorganic ammonium salt in the cerium salt aqueous solution can be 1:4.7 - 5.3, preferably 1:4.8 - 5.2, and more preferably 1:4.9 - 5.1. The molar concentration of the cerium salt in the cerium salt aqueous solution can be 0.08 - 0.2 mol / L, preferably 0.1 - 0.18 mol / L, and more preferably 0.12 - 0.15 mol / L.

[0016] In the present invention, the inorganic ammonium salt is preferably ammonium bicarbonate.

[0017] Step 2) is a hydrothermal reaction. Hydrothermally react the first reactant in a reaction kettle. The reaction kettle can be sealed first, so that during the reaction, no gas or liquid leaks outwards. The reaction kettle can be a stainless steel reaction kettle with a polytetrafluoroethylene lining. The reaction temperature in step 2) can be 180 - 200 °C, preferably 180 - 195 °C, and more preferably 180 - 190 °C. The hydrothermal reaction time can be 7 - 24 h, preferably 10 - 24 h, more preferably 15 - 20 h, and even more preferably 16 - 18 h.

[0018] In step 3), the second reactant can be first cooled down, for example, to room temperature, and then solid-liquid separation is carried out. The solid-liquid separation can be filtration or centrifugation, preferably centrifugation. After the solid-liquid separation, the separated solid can be first washed, and then the washed solid is dried to obtain the precursor. This is beneficial to obtaining a cerium oxide material with higher purity.

[0019] In step 4), after calcination, it can be naturally cooled to room temperature, and then ground to obtain the cerium oxide material.

[0020] According to the method for preparing the cerium oxide material of the present invention, preferably, in step 1), the cerium salt in the cerium salt aqueous solution is selected from at least one of cerium chloride, cerium nitrate, and cerium sulfate. In the present invention, the cerium salt can contain crystal water or can be anhydrous.

[0021] Preferably, the cerium salt in the cerium salt aqueous solution is selected from one of cerium chloride, cerium nitrate, and cerium sulfate.

[0022] According to a specific embodiment of the present invention, the cerium salt aqueous solution is formed by dissolving a cerium salt in water, and the cerium salt is cerium nitrate hexahydrate.

[0023] According to the method for preparing the cerium oxide material of the present invention, preferably, in step 1), the inorganic ammonium salt is ammonium bicarbonate. This is beneficial to obtaining the nano cerium oxide with good dispersibility and a popcorn-like morphology in the present invention.

[0024] According to the method for preparing the cerium oxide material of the present invention, preferably, in step 1), the molar ratio of the cerium salt to the inorganic ammonium salt in the cerium salt aqueous solution is 1:4.9 - 5.1. This is beneficial to obtaining the nano cerium oxide with good dispersibility and a popcorn-like morphology in the present invention, and there are no octahedral particles in the SEM image.

[0025] According to a specific embodiment of the present invention, the molar ratio of the cerium salt to the inorganic ammonium salt in the cerium salt aqueous solution is 1:5.0 - 5.1.

[0026] According to the method for preparing the cerium oxide material of the present invention, preferably, in step 1), the molar concentration of the cerium salt in the cerium salt aqueous solution is 0.1 - 0.15 mol / L. This is beneficial to obtaining the nano cerium oxide with good dispersibility and a popcorn-like morphology.

[0027] According to a specific embodiment of the present invention, the molar concentration of the cerium salt in the cerium salt aqueous solution is 0.12 - 0.14 mol / L.

[0028] According to the preparation method of the cerium oxide material of the present invention, preferably, in step 2), the first reactant is hydrothermally reacted at 180-200 °C for 15-20 h to obtain a second reactant. This is conducive to obtaining nano-ceria with good dispersibility and a popcorn-like morphology.

[0029] According to the preparation method of the cerium oxide material of the present invention, preferably, in step 3), the washing solvent is selected from at least one of methanol, ethanol, isopropanol, acetone, and water.

[0030] In the present invention, preferably, the washing solvent is selected from one of methanol, ethanol, isopropanol, acetone, and water, and more preferably ethanol. For example, it can be anhydrous ethanol.

[0031] According to the preparation method of the cerium oxide material of the present invention, preferably, in step 3), the drying temperature is 60-100 °C and the drying time is 6-18 h. This is conducive to obtaining nano-ceria with a specific morphology.

[0032] In the present invention, the drying temperature can be 60-100 °C, preferably 80-90 °C. The drying time can be 6-18 h, preferably 10-15 h.

[0033] According to the preparation method of the cerium oxide material of the present invention, preferably, in step 4), the calcination temperature is 600-700 °C and the calcination time is 2-4 h. This is conducive to obtaining nano-ceria with a specific morphology.

[0034] In the present invention, the calcination temperature is preferably 600-650 °C. The calcination time is preferably 2-3 h.

[0035] On the other hand, the present invention also provides a cerium oxide material prepared according to the above-mentioned preparation method. The cerium oxide material has a particle size of 100-200 nm, a popcorn-like morphology, surface grooves, and no octahedral particles.

[0036] The cerium oxide material obtained by the present invention is a cerium oxide powder. The particles in its SEM image have a specific morphology (substantially popcorn-like), many surface grooves, a particle size of 100-200 nm, and good dispersibility, and can be used in the polishing field.

[0037] The inventor believes that cerium oxide with a popcorn-like morphology has advantages such as a large specific surface area, good dispersibility, and abundant surface active sites. The large specific surface area enables it to provide more reaction active centers, enhance the chemical reaction with the surface of the material to be polished, and improve the polishing efficiency; good dispersibility can ensure the stability of the polishing liquid during storage and use, reduce particle agglomeration, and avoid polishing quality problems caused by particle agglomeration; abundant surface active sites help to act more evenly with the surface of the material to be polished, achieve more precise control of material removal, and thus obtain better surface flatness and lower surface roughness during the CMP polishing process.

[0038] The cerium oxide material prepared by the preparation method of the present invention has a particle size of 100 - 200 nm, a generally popcorn-like morphology, no octahedral particles, and good dispersibility. In addition, the preparation method of the present invention does not add any surfactants, does not use organic solvents, and only uses water as a solvent, with lower costs. Moreover, the preparation method of the present invention is relatively simple to operate and the process is relatively stable. Description of the Drawings

[0039] Figure 1 XRD diagram of the cerium oxide material which is the product of Example 1.

[0040] Figure 2 SEM diagram of the cerium oxide material which is the product of Example 1.

[0041] Figure 3 EDS diagram of the cerium oxide material which is the product of Example 1.

[0042] Figure 4 SEM diagram of the cerium oxide material which is the product of Comparative Example 1. Detailed Description of the Invention

[0043] The following introduces the test methods used in the following examples and comparative examples:

[0044] XRD: Test was carried out using an X’Pert PRO X-ray diffractometer.

[0045] SEM, EDS: Test was carried out using a ZEISS Sigma 500 field emission scanning electron microscope.

[0046] Example 1

[0047] Dissolve 1.74 g (0.004 mol) of cerium nitrate hexahydrate in 30 mL of deionized water, stir and disperse for 10 min to obtain an aqueous cerium nitrate solution.

[0048] Under stirring, 1.581 g (0.02 mol) of ammonium bicarbonate was added to an aqueous cerium nitrate solution. After the addition, stirring was continued for 2 h to obtain a first reactant. Among them, the molar ratio of the cerium salt in the aqueous cerium nitrate solution to ammonium bicarbonate was 1:5.

[0049] The first reactant was placed in a sealed autoclave and hydrothermally reacted at 180 °C for 16 h to obtain a second reactant.

[0050] After the reaction was completed and cooled to room temperature, the second reactant was centrifuged to obtain a white precipitate. The centrifuged white precipitate was washed with absolute ethanol, and the washed solid was dried at 80 °C for 12 h to obtain a precursor.

[0051] The precursor was calcined at 600 °C for 2 h and ground to obtain a cerium oxide material.

[0052] The XRD results of the cerium oxide material obtained in this example are shown in Figure 1 The SEM and EDS results are shown in Figure 2 and Figure 3 respectively.

[0053] From the Figure 1 XRD pattern, it can be seen that the characteristic peaks of the obtained cerium oxide material are very sharp, indicating that the crystallinity of the cerium oxide material is good, and the diffraction peaks of XRD correspond to the cerium oxide diffraction peaks identified by the standard PDF card JCPDS No. 34-0394, proving that the obtained is cerium oxide.

[0054] From the Figure 3 EDS pattern, it can be seen that by performing dot analysis on the surface of the obtained cerium oxide material, its composition is cerium oxide.

[0055] From the Figure 2 SEM image, it can be seen that the surface of the obtained cerium oxide material has grooves, its morphology is generally popcorn-like, the particle size is uniform, the particle diameter is 100-200 nm, and the dispersibility is good.

[0056] Example 2

[0057] 1.74 g (0.004 mol) of cerium nitrate hexahydrate was dissolved in 30 mL of deionized water and stirred and dispersed for 10 min to obtain an aqueous cerium nitrate solution.

[0058] Under stirring, 1.581 g (0.02 mol) of ammonium bicarbonate was added to the aqueous cerium nitrate solution. After the addition, stirring was continued for 2 h to obtain a first reactant. Among them, the molar ratio of the cerium salt in the aqueous cerium nitrate solution to ammonium bicarbonate was 1:5.

[0059] The first reactant was placed in a sealed autoclave and hydrothermally reacted at 180 °C for 18 h to obtain a second reactant.

[0060] After the reaction was completed, the temperature was lowered to room temperature, and the second reactant was centrifuged to obtain a white precipitate. The white precipitate obtained by centrifugation was washed with anhydrous ethanol, and the washed solid was dried at 80° C. for 12 h to obtain a precursor.

[0061] The precursor was calcined at 600° C. for 3 h and ground to obtain cerium oxide material.

[0062] The test results are basically similar to those of Example 1. The surface of the cerium oxide material obtained in this example has grooves, and its morphology is generally popcorn-shaped. The particle size is relatively uniform, the particle size is between 100 and 200 nm, and the dispersion is good.

[0063] Comparative Example 1

[0064] 2 g (0.0046 mol) of cerium nitrate hexahydrate was dissolved in 30 mL of deionized water, and the mixture was stirred and dispersed for 10 min to obtain a cerium nitrate aqueous solution.

[0065] Under stirring, 1.581 g (0.02 mol) of ammonium bicarbonate was added to the cerium nitrate aqueous solution, and after the addition, the stirring was continued for 2 hours to obtain the first reactant. The molar ratio of the cerium salt to the ammonium bicarbonate in the cerium nitrate aqueous solution was 1:4.35.

[0066] The first reactant was placed in a sealed reactor and subjected to a hydrothermal reaction at 180° C. for 16 h to obtain a second reactant.

[0067] After the reaction was completed, the temperature was lowered to room temperature, and the second reactant was centrifuged to obtain a white precipitate. The white precipitate obtained by centrifugation was washed with anhydrous ethanol, and the washed solid was dried at 80° C. for 12 h to obtain a precursor.

[0068] The precursor was calcined at 600° C. for 2 h and ground to obtain cerium oxide material.

[0069] The SEM results of the cerium oxide material obtained in this comparative example are shown in Figure 4 .Depend on Figure 4 and Figure 2 It can be seen that compared with Example 1, the particles of the cerium oxide material obtained in this comparative example are not uniform, and there are obvious octahedral particles. The SEM results of this comparative example are significantly different from those of Example 1.

[0070] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing a cerium oxide material, characterized in that: The following steps are involved: 1) adding an inorganic ammonium salt to a cerium salt aqueous solution under stirring, and continuing stirring for 1 to 3 hours after the addition to obtain a first reactant; wherein the molar ratio of the cerium salt to the inorganic ammonium salt in the cerium salt aqueous solution is 1:4.7 to 5.3, and the inorganic ammonium salt is ammonium carbonate and / or ammonium bicarbonate; and the molar concentration of the cerium salt in the cerium salt aqueous solution is 0.08 to 0.2 mol / L; 2) hydrothermally reacting the first reactant at 180-200° C. for 7-24 hours to obtain a second reactant; 3) separating the second reactant into solid and liquid, washing the separated solid, and drying the washed solid to obtain a precursor; 4) calcining the precursor at 600-900° C. for 2-5 hours to obtain cerium oxide material.

2. The preparation method according to claim 1, characterized in that: In step 1), the cerium salt in the cerium salt aqueous solution is selected from at least one of cerium chloride, cerium nitrate and cerium sulfate.

3. The preparation method according to claim 1, characterized in that: In step 1), the inorganic ammonium salt is ammonium bicarbonate.

4. The preparation method according to claim 1, characterized in that: In step 1), the molar ratio of the cerium salt to the inorganic ammonium salt in the cerium salt aqueous solution is 1:4.9-5.

1.

5. The preparation method according to claim 1, characterized in that: In step 1), the molar concentration of the cerium salt in the cerium salt aqueous solution is 0.1 to 0.15 mol / L.

6. The preparation method according to claim 1, characterized in that: In step 2), the first reactant is subjected to a hydrothermal reaction at 180-200° C. for 15-20 hours to obtain a second reactant.

7. The preparation method according to claim 1, characterized in that: In step 3), the washing solvent is selected from at least one of methanol, ethanol, isopropanol, acetone and water.

8. The preparation method according to claim 1, characterized in that: In step 3), the drying temperature is 60-100° C. and the drying time is 6-18 hours.

9. The preparation method according to claim 1, characterized in that: In step 4), the calcination temperature is 600-700° C. and the calcination time is 2-4 hours.

10. A cerium oxide material, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 9. The particle size of the cerium oxide material is 100 to 200 nm, and its morphology is generally popcorn-shaped, with grooves on the surface, and no octahedral particles exist.

Images