Polyhedral cerium oxide nanoparticles and preparation method and application thereof

Abstract

The present invention discloses a method for preparing polyhedral cerium oxide nanoparticles, comprising preparing a cerium salt solution, a precipitant solution, and an additive solution, each of which is stirred and bubbling with gas; uniformly mixing the cerium salt solution, the precipitant solution, and the additive solution, stirring and bubbling with gas to obtain a mixed solution; reacting the mixed solution, and then centrifuging, washing, drying, and calcining to obtain polyhedral cerium oxide nanoparticles. The present invention also provides polyhedral cerium oxide nanoparticles and their applications. The present invention provides a method for preparing polyhedral cerium oxide nanoparticles, which is synthesized in one step using a hydrothermal method. The required raw materials are readily available and non-toxic, the preparation process is simple, the production cost is low, and the synthesized cerium oxide has a uniform particle size distribution that can be controlled within 100-200 nm. The appropriate particle size is conducive to maintaining a high degree of dispersion of the polishing liquid and increasing the polishing rate during the polishing process.

Description

Technical Field

[0001] The present 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 component of modern semiconductor manufacturing processes. CMP combines chemical etching and mechanical polishing to achieve high-precision material removal, resulting in a surface with nanometer-level flatness. It is widely used in silicon wafer surface planarization and multi-layer metal interconnect planarization.

[0003] In traditional CMP processes, cerium oxide (CeO2) is widely used due to its excellent polishing performance, especially its good selectivity in sub-trench isolation processes. However, traditional cerium oxide particles are often large in size and have poor dispersion, which can easily cause scratches during polishing and affect surface quality. With the continuous miniaturization of semiconductor devices, the precision requirements of CMP processes are becoming increasingly stringent, and there is an urgent need to develop polishing materials with higher performance. Nano-cerium oxide, with its small particle size, large specific surface area, and high chemical activity, exhibits many advantages in CMP processes. Research has 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 booming semiconductor industry, a large number of methods for preparing cerium oxide with various morphologies for use in polishing fluids have been reported. Chinese patent CN115058199A discloses a method for preparing a highly dispersible spherical nano-cerium oxide polishing fluid, which can effectively enhance the dispersibility of the polishing fluid. Chinese patent CN115028185A discloses a method for preparing corncob-shaped cerium oxide, which can effectively enhance the polishing rate of the polishing fluid. However, there are still some challenges in achieving both enhanced polishing rate and dispersibility. Summary of the Invention

[0005] In response to the aforementioned shortcomings of the prior art, the present invention provides a method for preparing polyhedral cerium oxide nanoparticles. This method utilizes a one-step hydrothermal synthesis method, utilizing readily available and non-toxic raw materials. The preparation process is simple, resulting in low production costs. The synthesized cerium oxide has a uniform particle size distribution, controllable within the range of 100-200 nm. This optimal particle size helps maintain high dispersion in the polishing solution, increasing the polishing rate during the polishing process.

[0006] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0007] A method for preparing polyhedral cerium oxide nanoparticles comprises the following steps:

[0008] preparing a cerium salt solution, a precipitant solution, and an additive solution, respectively, and stirring and bubbling with gas;

[0009] The cerium salt solution, the precipitant solution, and the additive solution are uniformly mixed, stirred, and bubbling with gas to obtain a mixed solution;

[0010] The mixed solution is reacted, centrifuged, washed, dried and calcined to obtain polyhedral cerium oxide nanoparticles.

[0011] 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.

[0012] 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.

[0013] 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 of nano-cerium oxide particles, and its effect 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 guides the growth and variation of different crystal planes and the formation of different shapes, facilitating the synthesis of cerium oxide nanoparticles with uniform particle size distribution.

[0014] According to one aspect of the present invention, the gas is nitrogen or argon.

[0015] According to one aspect of the present invention, the concentration of the cerium salt solution is 0.01-2 mol / L.

[0016] According to one aspect of the present invention, the concentration of the precipitant solution is 0.01-1 mol / L.

[0017] According to one aspect of the present invention, the concentration of the additive solution is 0.001-0.1 mol / L.

[0018] According to one aspect of the present invention, the reaction is carried out at 110-200° C. for 10-20 h.

[0019] According to one aspect of the present invention, the reaction is carried out at 120-150° C. for 10-15 hours.

[0020] According to one aspect of the present invention, the calcination temperature is 500-700°C.

[0021] According to one aspect of the present invention, the polyhedral cerium oxide nanoparticles prepared by the above preparation method.

[0022] According to one aspect of the present invention, the polyhedral cerium oxide nanoparticles are used in preparing a polishing liquid.

[0023] The advantages of the present invention include a one-step hydrothermal synthesis of polyhedral nanoceria using readily available and non-toxic raw materials, a simple preparation process, and low production costs. The synthesized cerium oxide has a uniform particle size distribution, controllable to between 100 and 200 nm. This optimal particle size helps maintain high dispersion in the polishing solution, increasing the polishing rate during the polishing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. 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 any creative work.

[0025] Figure 1 This is the SEM image of cerium oxide obtained in Example 1;

[0026] Figure 2 This is the SEM image of cerium oxide obtained in Example 2;

[0027] Figure 3 This is the SEM image of cerium oxide obtained in Example 3;

[0028] Figure 4 This is the SEM image of cerium oxide obtained in Example 4;

[0029] Figure 5 This is the SEM image of cerium oxide obtained in Example 5;

[0030] Figure 6 This is the SEM image of cerium oxide obtained in Comparative Example 1;

[0031] Figure 7 This is the SEM image of cerium oxide obtained in Comparative Example 2. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of cysteine at room temperature. Stir and aerate each solution with nitrogen for 30 minutes. Combine the three solutions and continue stirring and aerating with nitrogen for another 30 minutes.

[0035] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0036] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 1 The following is a SEM image of cerium oxide prepared in this example.

[0037] Example 2

[0038] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of cysteine at room temperature. Stir and aerate each solution with nitrogen for 30 minutes. Combine the three solutions and continue stirring and aerating with nitrogen for another 30 minutes.

[0039] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0040] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours. Place the resulting powder in a muffle furnace and calcine it at 650°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 2 The following is a SEM image of cerium oxide prepared in this example.

[0041] Example 3

[0042] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of cysteine at room temperature. Stir and aerate each solution with nitrogen for 30 minutes. Combine the three solutions and continue stirring and aerating with nitrogen for another 30 minutes.

[0043] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0044] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 700°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 3 The following is a SEM image of cerium oxide prepared in this example.

[0045] Example 4

[0046] 1. Prepare a 0.2 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of cysteine at room temperature. Stir and aerate each solution with nitrogen for 30 minutes. Combine the three solutions and continue stirring and aerating with nitrogen for another 30 minutes.

[0047] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0048] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 4 The following is a SEM image of cerium oxide prepared in this example.

[0049] Example 5

[0050] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of phenylalanine at room temperature. Stir and aerate each solution with nitrogen for 30 minutes. Combine the three solutions and continue stirring and aerating with nitrogen for another 30 minutes.

[0051] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0052] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 600°C for 3 hours to obtain polyhedral nano-cerium oxide. Figure 5 The following is a SEM image of cerium oxide prepared in this example.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that nitrogen bubbling was not used.

[0055] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.25 mol / L aqueous solution of ammonium carbonate, and a 1.2 mmol / L aqueous solution of cysteine at room temperature. Stir each solution for 30 minutes. Combine the three solutions and continue stirring for another 30 minutes.

[0056] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0057] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 600°C for 3 hours to obtain nano-cerium oxide. Figure 6 This is the SEM image of cerium oxide prepared in this comparative example.

[0058] Comparative Example 2

[0059] The difference from Example 1 is that the additive used is CTAB and nitrogen bubbling is not used.

[0060] 1. Prepare a 0.1 mol / L aqueous solution of cerium nitrate, a 0.6 mol / L aqueous solution of ammonium carbonate, and a 1.4 mmol / L aqueous solution of TAB at room temperature. Stir each solution for 30 minutes. Combine the three solutions and continue stirring for another 30 minutes.

[0061] 2. The mixed solution treated in step 1 was transferred to a reactor lined with polytetrafluoroethylene. The reaction temperature was 140°C and the reaction time was 12 hours to obtain a precursor. After the reactor was naturally cooled, the obtained precursor was centrifuged and washed with deionized water for more than three times.

[0062] 3. Transfer the precursor obtained in step 2 to an oven and dry it at 80°C for 10 hours to obtain a powder. Place the obtained powder in a muffle furnace and calcine it at 600°C for 3 hours to obtain nano-cerium oxide. Figure 7 This is the SEM image of cerium oxide prepared in this comparative example.

[0063] Morphological characterization:

[0064] 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.

[0065] 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.

[0066] Polishing and dispersion coefficient test:

[0067] To verify the polishing performance of the polyhedral cerium oxide prepared in the present invention when used to prepare a polishing solution, chemical mechanical polishing solutions were prepared using the cerium oxide particles obtained in Examples 1-5 and Comparative Examples 1-2. The polishing rates of these polishing solutions on TEOS were further measured. The specific test conditions are as follows:

[0068] The cerium oxide prepared in Examples 1-5 and Comparative Examples 1-2 was prepared into polishing slurries. The slurries were diluted to a solid content of 5 wt%, and the pH of the system was adjusted to approximately 5.5. The polishing removal rate (RR) of each polishing slurry on a TEOS blank wafer was evaluated. Polishing conditions were as follows: an AMAT 300mm polisher and an IC1010 polishing pad were used for polishing at a rotation speed of 96 rpm / 85 rpm, a downward pressure of 3 psi, a polishing slurry flow rate of 100 mL / min, and a polishing time of 60 seconds.

[0069] Furthermore, the dispersion coefficients of the polishing solutions obtained in Examples 1-5 and Comparative Examples 1-2 were measured using an ALV / CGS-3 dynamic and static laser light scattering instrument.

[0070] The polishing rates and dispersion coefficients of the polishing solutions prepared from cerium oxide obtained in Examples 1-5 and Comparative Examples 1-2 were recorded to obtain Table 1.

[0071] Table 1

[0072]

[0073] As shown in Table 1, the nano-cerium oxides of Examples 1-5 have lower PDI values, indicating a more uniform size distribution and better monodispersity. Furthermore, the nano-cerium oxides of Examples 1-5 can be used in polishing liquids to increase the polishing rate of silicon dioxide.

[0074] The advantages of the present invention include a one-step hydrothermal synthesis of polyhedral nano-cerium oxide using readily available and non-toxic raw materials, a simple preparation process, and low production costs. The synthesized cerium oxide has a uniform particle size distribution, controllable to between 100 and 200 nm. When used in a polishing liquid, the appropriate particle size facilitates high dispersion in the polishing liquid. The polyhedral structure of the cerium oxide particles provides a greater contact area during polishing, which, to a certain extent, helps increase the polishing rate.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing polyhedral cerium oxide nanoparticles, characterized in that: The steps include: A cerium salt solution with a concentration of 0.01-2 mol / L, a precipitant solution with a concentration of 0.01-1 mol / L, and an additive solution with a concentration of 0.001-0.1 mol / L are prepared, and the solutions are stirred and bubbled with gas, wherein the additive is one of cysteine and phenylalanine, and the gas is nitrogen; The cerium salt solution, the precipitant solution, and the additive solution are uniformly mixed, stirred, and bubbling with gas to obtain a mixed solution; The mixed solution is subjected to a hydrothermal synthesis reaction at 110-200° C. for 10-20 hours, and then centrifuged, washed, dried and calcined to obtain polyhedral cerium oxide nanoparticles.

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

4. A polyhedral cerium oxide nanoparticle, characterized in that: The polyhedral cerium oxide nanoparticles are prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the polyhedral cerium oxide nanoparticles according to claim 4 in preparing a polishing liquid.

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