Polyhedral cerium oxide nanoparticles as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of polyhedral cerium oxide nanoparticles, which comprises the following steps: preparing a cerium salt solution, preparing a precipitator solution, preparing an additive solution, respectively keeping stirring and bubbling by using gas; uniformly mixing the cerium salt solution, the precipitant solution and the additive solution, keeping stirring and bubbling with gas to obtain a mixed solution; and reacting the mixed solution, centrifuging, washing, drying and roasting to obtain the polyhedral cerium oxide nanoparticles. The invention also provides the polyhedral cerium oxide nanoparticles and application thereof. According to the preparation method of the polyhedral cerium oxide nano-particles, one-step synthesis is performed by adopting a hydrothermal method, the required raw materials are easy to purchase and non-toxic, the preparation process is simple, the production cost is low, and the particle size distribution of the synthesized cerium oxide is uniform and can be controlled to be 100-200nm. The proper particle size is beneficial to keeping high dispersion of the polishing solution and increasing the polishing rate in the polishing process.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic nanomaterials, and in particular to polyhedral cerium oxide nanoparticles and a preparation method and application thereof. Background Art

[0002] Chemical Mechanical Planarization (CMP) is a key technology used to achieve highly flat wafer surfaces during semiconductor manufacturing, and is an indispensable part of modern semiconductor manufacturing processes. CMP combines chemical etching and mechanical grinding to achieve high-precision material removal, thereby obtaining a surface with nanometer-level flatness. It is widely used in silicon wafer surface flattening, multi-layer metal interconnect flattening, and other links.

[0003] In the traditional CMP process, cerium oxide (CeO 2 ) is widely used due to its excellent polishing performance, especially its good selectivity in the trench isolation process. However, traditional cerium oxide particles are often large in size and poor in dispersion, which leads to scratches during the polishing process and affects the surface quality. With the continuous miniaturization of semiconductor devices, the precision requirements for CMP processes are becoming higher and higher, and there is an urgent need to develop polishing materials with better performance. Nano cerium oxide has the characteristics of small particle size, large specific surface area, and high chemical activity, and exhibits many advantages in the CMP process. Studies have shown that nano cerium oxide, as a CMP abrasive, can significantly improve polishing efficiency, reduce surface roughness, and improve surface quality.

[0004] In recent years, due to the vigorous development of the semiconductor industry, a large number of methods for preparing cerium oxide with various morphologies used in polishing liquids have been reported. Chinese patent CN115058199A discloses a method for preparing a spherical nano-cerium oxide polishing liquid with high dispersibility, which can effectively enhance the dispersibility of the polishing liquid. Chinese patent CN115028185A discloses a method for preparing corncob-shaped cerium oxide, and the polishing liquid prepared therefrom can effectively enhance the polishing rate. However, there are still some challenges in enhancing the polishing rate and dispersibility at the same time. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing polyhedral cerium oxide nanoparticles, which is synthesized in one step by a hydrothermal method, the required raw materials are easily available and non-toxic, the preparation process is simple, the production cost is low, and the synthesized cerium oxide particle size distribution is uniform and can be controlled within 100-200nm. The appropriate particle size is conducive to maintaining the high dispersion of the polishing liquid and increasing the polishing rate during the polishing process.

[0006] To achieve the above object, the embodiments of the present invention adopt the following technical solutions: A method for preparing polyhedral cerium oxide nanoparticles comprises the following steps: preparing a cerium salt solution, a precipitant solution, and an additive solution, and respectively maintaining stirring and using gas bubbling; The cerium salt solution, the precipitant solution and the additive solution are mixed uniformly, kept stirring, and gas bubbling is used to obtain a mixed solution; The mixed solution is reacted, centrifuged, washed, dried and calcined to obtain polyhedral cerium oxide nanoparticles.

[0007] According to one aspect of the present invention, the cerium salt is at least one of cerium nitrate, cerium chloride, cerium sulfate, cerium acetate, ammonium cerium nitrate, ammonium cerium sulfate and / or cerium IV nitrate.

[0008] According to one aspect of the present invention, the precipitant is at least one of urea, ammonium carbonate, ammonium bicarbonate, potassium bicarbonate, ethylenediamine and / or ammonium phosphate.

[0009] According to one aspect of the present invention, the additive is at least one of proline, citric acid, glycine, cysteine, ethylenediaminetetraacetic acid, glutamic acid, phenylalanine and / or lysine. The additive plays a structural guiding role in the preparation process of nano cerium oxide particles, and its influence on the morphology of cerium oxide is related to the molecular structure of the additive. The combination of functional groups and steric hindrance of different additives will guide the growth changes of different crystal planes and the formation of different shapes, which is conducive to the synthesis of cerium oxide nanoparticles with uniform particle size distribution.

[0010] According to one aspect of the present invention, the gas is nitrogen or argon.

[0011] According to one aspect of the present invention, the concentration of the cerium salt solution is 0.01-2 mol / L.

[0012] According to one aspect of the present invention, the concentration of the precipitant solution is 0.01-1 mol / L.

[0013] According to one aspect of the present invention, the concentration of the additive solution is 0.001-0.1 mol / L.

[0014] According to one aspect of the present invention, the reaction is carried out at 110-200° C. for 10-20 h.

[0015] According to one aspect of the present invention, the reaction is carried out at 120-150° C. for 10-15 hours.

[0016] According to one aspect of the present invention, the calcination temperature is 500-700°C.

[0017] According to one aspect of the present invention, the polyhedral cerium oxide nanoparticles prepared by the above preparation method.

[0018] According to one aspect of the present invention, the polyhedral cerium oxide nanoparticles are used in preparing a polishing liquid.

[0019] The advantages of the present invention are: the polyhedral nano-cerium oxide is synthesized in one step by a hydrothermal method, the required raw materials are easily available and non-toxic, the preparation process is simple, the production cost is low, and the particle size distribution of the synthesized cerium oxide is uniform and can be controlled within 100-200nm. The appropriate particle size is conducive to maintaining the high dispersion of the polishing liquid and increasing the polishing rate during the polishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is the SEM image of cerium oxide obtained in Example 1; Figure 2 This is the SEM image of cerium oxide obtained in Example 2; Figure 3 This is the SEM image of cerium oxide obtained in Example 3; Figure 4 This is the SEM image of cerium oxide obtained in Example 4; Figure 5 This is the SEM image of cerium oxide obtained in Example 5; Figure 6 This is the SEM image of cerium oxide obtained in Comparative Example 1; Figure 7 This is the SEM image of cerium oxide obtained in Comparative Example 2. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.25 mol / L ammonium carbonate aqueous solution, and 1.2 mmol / L cysteine ​​aqueous solution at room temperature. Stir and flow nitrogen for 30 min respectively. Mix the three solutions and continue to stir and flow nitrogen for 30 min.

[0025] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0026] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 1 This is the SEM image of cerium oxide prepared in this example.

[0027] Example 2

[0028] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.25 mol / L ammonium carbonate aqueous solution, and 1.2 mmol / L cysteine ​​aqueous solution at room temperature. Stir and flow nitrogen for 30 min respectively. Mix the three solutions and continue to stir and flow nitrogen for 30 min.

[0029] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0030] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours. The obtained powder is placed in a muffle furnace and calcined at 650°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 2 This is the SEM image of cerium oxide prepared in this example.

[0031] Example 3

[0032] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.25 mol / L ammonium carbonate aqueous solution, and 1.2 mmol / L cysteine ​​aqueous solution at room temperature. Stir and flow nitrogen for 30 min respectively. Mix the three solutions and continue to stir and flow nitrogen for 30 min.

[0033] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0034] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 700°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 3 This is the SEM image of cerium oxide prepared in this example.

[0035] Example 4

[0036] 1. Prepare 0.2 mol / L cerium nitrate aqueous solution, 0.25 mol / L ammonium carbonate aqueous solution and 1.2 mmol / L cysteine ​​aqueous solution at room temperature. Stir and flow nitrogen for 30 min respectively. Mix the three solutions and continue to stir and flow nitrogen for 30 min.

[0037] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0038] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 4 This is the SEM image of cerium oxide prepared in this example.

[0039] Example 5

[0040] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.25 mol / L ammonium carbonate aqueous solution, and 1.2 mmol / L phenylalanine aqueous solution at room temperature. Stir and flow nitrogen for 30 min respectively. Mix the three solutions and continue to stir and flow nitrogen for 30 min.

[0041] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0042] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 5 This is the SEM image of cerium oxide prepared in this example.

[0043] Comparative Example 1 The difference from Example 1 is that nitrogen bubbling was not used.

[0044] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.6 mol / L ammonium carbonate aqueous solution, and 1.2 mmol / L cysteine ​​aqueous solution at room temperature. Stir them for 30 min respectively, mix the three solutions, and continue stirring for 30 min.

[0045] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0046] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 600°C for 3 hours to obtain nano-cerium oxide. Figure 6 This is the SEM image of cerium oxide obtained in this comparative example.

[0047] Comparative Example 2 The difference from Example 1 is that the additive used is CTAB, and nitrogen bubbling is not used.

[0048] 1. Prepare 0.1 mol / L cerium nitrate aqueous solution, 0.6 mol / L ammonium carbonate aqueous solution, and 1.4 mmol / L TAB aqueous solution at room temperature. Stir them for 30 min respectively, mix the three solutions, and continue stirring for 30 min.

[0049] 2. The mixed solution treated in step 1 is transferred to a reactor with a polytetrafluoroethylene liner, the reaction temperature is 140°C, the reaction time is 12 hours, and a precursor is obtained. After the reactor is naturally cooled, the obtained precursor is centrifuged and washed with deionized water for more than three times.

[0050] 3. The precursor obtained in step 2 is transferred to an oven and dried at 80°C for 10 hours to obtain a powder. The obtained powder is placed in a muffle furnace and calcined at 600°C for 3 hours to obtain nano-cerium oxide. Figure 7 This is the SEM image of cerium oxide obtained in this comparative example.

[0051] Morphological characterization: Depend on Figures 1 to 5 It can be seen that the cerium oxide materials prepared in Examples 1 to 5 of the present application have uniform particle size distribution, polyhedral structure, and diameters of 100-200 nm. However, the cerium oxide material prepared in Comparative Example 1 has strip-shaped cerium oxide. The cerium oxide material prepared in Comparative Example 2 has an irregular shape.

[0052] It can be seen that the present application successfully guides the growth direction of cerium oxide crystals through appropriate additives and specific reaction conditions, so that it forms a polyhedral structure with uniform particle size distribution.

[0053] Polishing and dispersion coefficient test: In order to verify the polishing performance of the polyhedral cerium oxide prepared in the present invention for preparing a polishing liquid, the cerium oxide particles obtained in the above Examples 1-5 and Comparative Examples 1-2 were used to prepare a chemical mechanical polishing liquid, and the polishing rate of the prepared polishing liquid on TEOS was further measured. The specific test conditions are as follows: The cerium oxide prepared in Examples 1-5 and Comparative Examples 1-2 was made into a polishing liquid, and the polishing liquid was diluted to a solid content of 5wt%, and the system pH was adjusted to about 5.5. The TEOS blank wafer polishing removal rate (RR) of each group of polishing liquids was evaluated. The polishing conditions were: polishing with an AMAT 300mm polisher and an IC1010 pad polishing pad, a rotation speed of 96rpm / 85rpm, a downward pressure of 3psi, a polishing liquid flow rate of 100mL / min, and a polishing time of 60 seconds.

[0054] Furthermore, the dispersion coefficients of the polishing solutions obtained in Examples 1-5 and Comparative Examples 1-2 were tested using an ALV / CGS-3 dynamic and static laser light scattering instrument.

[0055] The polishing rates and dispersion coefficients of the polishing liquids made of cerium oxide obtained in Examples 1-5 and Comparative Examples 1-2 were recorded to obtain Table 1.

[0056] Table 1

[0057] As shown in Table 1, the nano-cerium oxide of Examples 1-5 has a lower PDI value, which shows that its size distribution is more uniform and has better monodispersity. At the same time, the nano-cerium oxide of Examples 1-5 is used in the polishing liquid to improve the polishing rate of silicon dioxide.

[0058] The advantages of the present invention are as follows: the polyhedral nano-cerium oxide is synthesized in one step by a hydrothermal method, the required raw materials are easily available and non-toxic, the preparation process is simple, the production cost is low, and the particle size distribution of the synthesized cerium oxide is uniform and can be controlled within 100-200nm. The nano-cerium oxide is applied to the polishing liquid, and the appropriate particle size is conducive to maintaining the high dispersion of the polishing liquid. The polyhedral cerium oxide particles can provide more contact area during the polishing process, which helps to increase the polishing rate during the polishing process to a certain extent.

[0059] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for preparing polyhedral cerium oxide nanoparticles, characterized in that: The steps include: preparing a cerium salt solution, a precipitant solution, and an additive solution, respectively, and stirring and bubbling with gas; The cerium salt solution, the precipitant solution and the additive solution are mixed uniformly, kept stirring, and gas bubbling is used to obtain a mixed solution; The mixed solution is reacted, centrifuged, washed, dried and calcined to obtain polyhedral cerium oxide nanoparticles.

2. The method for preparing polyhedral cerium oxide nanoparticles according to claim 1, characterized in that: The cerium salt is at least one of cerium nitrate, cerium chloride, cerium sulfate, cerium acetate, ammonium cerium nitrate, ammonium cerium sulfate and / or cerium IV nitrate.

3. The method for preparing polyhedral cerium oxide nanoparticles according to claim 1, characterized in that: The precipitant is at least one of urea, ammonium carbonate, ammonium bicarbonate, potassium bicarbonate, ethylenediamine and / or ammonium phosphate.

4. The method for preparing polyhedral cerium oxide nanoparticles according to claim 1, characterized in that: The additive is at least one of proline, citric acid, glycine, cysteine, ethylenediaminetetraacetic acid, glutamic acid, phenylalanine and / or lysine.

5. The method for preparing polyhedral cerium oxide nanoparticles according to claim 1, characterized in that: The concentration of the cerium salt solution is 0.01-2 mol / L.

6. The method for preparing polyhedral cerium oxide nanoparticles according to claim 5, characterized in that: The concentration of the precipitant solution is 0.01-1 mol / L.

7. The method for preparing polyhedral cerium oxide nanoparticles according to claim 6, characterized in that: The concentration of the additive solution is 0.001-0.1 mol / L.

8. The method for preparing polyhedral cerium oxide nanoparticles according to claim 7, characterized in that: The reaction is carried out at 110-200° C. for 10-20 hours.

9. A polyhedral cerium oxide nanoparticle, characterized in that: The polyhedral cerium oxide nanoparticles are prepared by the preparation method described in any one of claims 1-8.

10. Use of the polyhedral cerium oxide nanoparticles according to claim 9 in preparing a polishing liquid.

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