Particles and dispersion thereof, planarization composition and application thereof, semiconductor device and planarization method of substrate therefor

Abstract

The present invention provides a particle and a dispersion thereof, a planarization composition and its application, and a semiconductor device and a method for planarizing a substrate therefor. The particle is a spherical or quasi-spherical cerium oxide particle having multiple protrusions formed on its surface. The particle is composed of multiple grains, at least one of which has a particle size greater than or equal to 15 nm. Cerium oxide particles that meet these conditions have a high removal rate of substrate surface material without causing noticeable scratches on the substrate surface.

Description

Technical Field

[0001] The present application relates to the technical field of planarization treatment, and in particular to a particle and a dispersion thereof, a planarization composition and an application thereof, a semiconductor device and a planarization method for a substrate thereof. Background Art

[0002] Cerium oxide particles are typically used as abrasive particles in substrate surface planarization processes, helping to increase the material removal rate (MRR) of the substrate being treated. From the perspective of planarization applications, it is desirable not only for the cerium oxide particles to have a high MRR, but also for them to introduce fewer surface defects to the substrate during the planarization process. From the perspective of defect reduction, it is desirable for the cerium oxide particles to have a morphology close to a standard sphere. However, a smooth sphere often reduces contact with the surface of the treated substrate, which is not conducive to improving the MRR. Therefore, it is necessary to provide a new type of cerium oxide particle and its related applications that can simultaneously have high MRR and low processing defect characteristics. Summary of the Invention

[0003] In view of this, embodiments of the present application provide cerium oxide particles and their dispersion, a planarization composition and their application, and a planarization method for a semiconductor device and its substrate that can achieve both a high substrate material removal rate and low processing defects.

[0004] Specifically, the first aspect of an embodiment of the present application provides a particle, which is a cerium oxide particle, and the cerium oxide particle is a spherical or quasi-spherical particle with multiple protrusions formed on the surface. The spherical or quasi-spherical particle with multiple protrusions formed on the surface is composed of multiple grains, and the multiple grains include at least grains with a particle size greater than or equal to 15 nm.

[0005] The cerium oxide particles are spherical or quasi-spherical particles with multiple surface protrusions. The presence of these multiple surface protrusions can improve the MRR of the cerium oxide particles to the substrate surface. The multiple grains comprising the polycrystalline cerium oxide particles include at least grains with a particle size of 15 nm or greater, which can further ensure that the MRR of the cerium oxide particles to the substrate is further improved. The spherical or quasi-spherical morphology ensures that when the cerium oxide particles are used as abrasive particles for planarizing substrates, they will cause fewer surface scratch defects on the treated substrate. Therefore, the cerium oxide particles can effectively achieve a high MRR and low defectivity when used in chemical mechanical planarization processes.

[0006] In the embodiment of the present application, the sphericity of the cerium oxide particles is in the range of 0.8-1.0. The higher particle sphericity can reflect that the cerium oxide particles provided by the embodiment of the present application are closer to the standard sphere, which results in fewer substrate grinding defects.

[0007] In some embodiments of the present application, the plurality of crystal grains include at least those having a particle size in the range of 15 nm to 50 nm. In this case, the removal rate of the cerium oxide particles from the substrate surface material can be effectively increased while also preventing scratches on the substrate surface after treatment due to oversized crystal grains.

[0008] In the embodiment of the present application, the average width of the protrusions is greater than 10 nm. Protrusions with a wider average width may indicate that the protrusions are obvious extensions existing on the surface of the cerium oxide particles, thereby effectively improving the MRR of the cerium oxide particles to the substrate surface.

[0009] In the embodiment of the present application, the average height of the protrusions is greater than 5 nm. An appropriate average protrusion height can reflect that the protrusions are obvious epitaxies existing on the surface of the cerium oxide particles.

[0010] In the embodiment of the present application, the cerium oxide particles are free of pores. Because the cerium oxide particles are not simple aggregates of multiple single-crystal particles, but rather well-dispersed polycrystalline particles, the cerium oxide particles, which have no pores inside or on the surface, exhibit excellent stability during the planarization process.

[0011] In the embodiment of the present application, the trivalent cerium in the cerium oxide particles accounts for more than 30% of the total cerium element. The higher trivalent cerium content in the cerium oxide particles reflects a higher content of surface oxygen vacancies, correspondingly higher polishing activity, and thus further improving the substrate material removal rate.

[0012] In the embodiment of the present application, the cerium oxide particles do not contain carbon. The cerium oxide particles provided in the embodiment of the present application are sintered cerium oxide particles and do not contain organic matter.

[0013] In some embodiments of the present application, the D50 particle size of the cerium oxide particles is within the range of 30 nm to 300 nm as measured by dynamic light scattering. Polycrystalline cerium oxide particles have a suitable D50 particle size and are suitable for surface planarization of substrates used in the manufacture of semiconductor devices.

[0014] In some embodiments of the present application, the D50, D90, and D10 particle sizes of the cerium oxide particles, as measured by dynamic light scattering, satisfy the following ratio: (D90 - D10) / D50 is less than 0.83. A smaller ratio indicates a higher particle size concentration and a narrower particle size distribution of the cerium oxide particles.

[0015] In some embodiments of the present application, the specific surface area of the cerium oxide particles is 12-50 m 2 / g.

[0016] In some possible embodiments of the present application, the ratio of the average particle size of the cerium oxide particles measured based on electron microscopic images to the theoretical average particle size calculated based on the specific surface area of the cerium oxide particles is within a range of 1.5-4.5. The roughness index of the cerium oxide particles of the present application is suitably low, and the particles are less likely to agglomerate and cause defects such as scratches on the surface of the treated substrate.

[0017] A second aspect of the present invention provides a particle dispersion comprising the particles described in the first aspect of the present invention and a solvent. Because the particle dispersion comprises the cerium oxide particles described above, it can achieve both a high substrate material removal rate and low defectivity in a planarization process.

[0018] In the embodiment of the present application, the solvent includes water, or includes water and a water-soluble organic solvent.

[0019] A third aspect of the embodiments of the present application provides a planarization composition, which includes the particles described in the first aspect of the embodiments of the present application, or includes the particle dispersion described in the second aspect of the embodiments of the present application.

[0020] Since the planarization composition includes the cerium oxide particles of the present application, it can be used in a planarization process to achieve a high substrate material removal rate and low defects.

[0021] In some embodiments of the present application, the pH of the planarization composition is between 3 and 6. The planarization composition has an appropriate pH value to ensure that the cerium oxide particles are well dispersed and have a high content therein, so that the planarization composition achieves a good planarization effect.

[0022] In some embodiments of the present application, the planarization composition further comprises one or more of a pH adjuster, a dispersant, a thickener, a flow improver, and a surfactant.

[0023] In some embodiments of the present application, the cerium oxide particles in the planarization composition may contain 0.1 wt % to 1 wt %. A suitable content of cerium oxide particles in the planarization composition facilitates the planarization composition to achieve a high removal rate for silicon-containing dielectric layers such as silicon oxide.

[0024] The fourth aspect of the embodiments of the present application provides the use of the particle dispersion as described in the second aspect of the embodiments of the present application, or the planarization composition as described in the third aspect of the embodiments of the present application in planarizing a dielectric layer.

[0025] In some embodiments of the present application, the dielectric layer includes one or more of a silicon oxide layer, a silicon carbide layer, or a silicon nitride layer.

[0026] A fifth aspect of the present invention provides a method for planarizing a substrate, comprising polishing the surface of the substrate using the planarizing composition described in the third aspect of the present invention. Polishing the substrate using the planarizing composition of the present invention provides a high removal efficiency for unwanted material from the substrate surface, resulting in a relatively flat surface and fewer surface defects.

[0027] The present invention also provides a method for preparing the cerium oxide particles. The method may include the following steps:

[0028] (1) mixing an aqueous solution of an alkali, an aqueous solution of a water-soluble Ce(III) salt, and an acid to obtain a mixed solution; wherein the acid includes an inorganic acid and an organic acid;

[0029] (2) While maintaining the pH value of the mixed solution at greater than 8.0, heat-treating the mixed solution at a temperature below 100° C., collecting the obtained solid, and drying and calcining the solid at a high temperature to obtain the cerium oxide particles.

[0030] The preparation method can produce cerium oxide particles that meet the above requirements of the present application. When used in a planarization process, the cerium oxide particles can achieve both a high substrate material removal rate and low substrate defectivity. The preparation method is simple and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic structural diagram of a chemical mechanical planarization device provided in an embodiment of the present application.

[0032] Figure 2 This is a scanning electron microscope (SEM) photograph of the cerium oxide particles prepared in Example 1 of the present application.

[0033] Figure 3 This is a transmission electron microscope (TEM) photograph of the cerium oxide particles prepared in Example 1 of the present application.

[0034] Figure 4 This is the UV-Raman spectrum of the cerium oxide particles prepared in Example 1 of the present application.

[0035] Figure 5 This is the XRD spectrum of the cerium oxide particles prepared in Example 1 of the present application.

[0036] Figure 6 This is a SEM photograph of the cerium oxide particles provided in Example 2 of the present application.

[0037] Figure 7This is a SEM photograph of the cerium oxide particles provided in Example 3 of the present application.

[0038] Figure 8 This is a SEM photograph of the cerium oxide particles provided in Comparative Example 1.

[0039] Figure 9 This is a SEM photograph of the cerium oxide particles provided in Comparative Example 2.

[0040] Figure 10 This is a SEM photograph of the cerium oxide particles provided in Comparative Example 3.

[0041] Description of the main reference numerals: 100 - chemical mechanical planarization device, 1 - workbench, 2 - planarization pad, 3 - planarization head, 4 - substrate, 5 - planarization liquid supply assembly, 501 - planarization liquid. DETAILED DESCRIPTION

[0042] The embodiments of the present application will be described below with reference to the accompanying drawings.

[0043] Chemical mechanical planarization is a technology that achieves uniform flatness of the substrate surface during the semiconductor device manufacturing process. Its principle is a processing technology that combines chemical etching and mechanical removal. Figure 1 A schematic diagram of the structure of the chemical mechanical planarization device provided in the embodiment of the present application. Figure 1 The chemical mechanical planarization apparatus 100 includes a workbench 1, a planarization pad 2 placed on the workbench 1, a planarization head 3 suspended above the workbench 1, and a planarization liquid supply assembly 5. The workbench 1 and / or the planarization head 3 can rotate under the action of a motor. The substrate 4 to be processed can be fixedly mounted on the planarization head 3. The planarization liquid supply assembly 5 is used to provide a planarization liquid 501. The planarization liquid 501 is generally a chemical solution containing abrasive particles.

[0044] During the chemical mechanical planarization process, the substrate 4 to be treated is fixed at the bottom of the planarization head 3, with its treated surface facing the planarization pad 2. The rotating planarization head 3 presses with a certain pressure against the rotating planarization pad 2 located on the workbench 1. The planarization liquid supply assembly 5 provides planarization liquid 501 to the planarization pad 2. The planarization liquid 501 flows between the treated surface of the substrate 4 and the planarization pad 2. The liquid is evenly distributed into a thin liquid film due to the transmission and centrifugal action of the planarization pad 2. Through the dual chemical and mechanical effects of the liquid, the surface of the substrate 4 is treated, removing some unwanted materials and achieving a highly flat surface.

[0045] For substrates that need to remove a portion of the material such as silicon oxide, silicon nitride, etc., the leveling liquid 501 used is generally a chemical solution containing cerium oxide particles. Cerium oxide particles can form cerium-oxygen-silicon bonds with the surface of materials such as silicon oxide, thereby accelerating the removal rate of the silicon oxide material. Leveling liquids containing cerium oxide particles can also be used to polish silicon nitride, because under aqueous conditions, a portion of the material on the surface of silicon nitride will be converted into silicon oxide and can form cerium-oxygen-silicon bonds with cerium oxide particles, thereby being removed. However, the existing cerium oxide particles used as abrasive particles cannot take into account both a high material removal rate and low grinding defects. In order to obtain a good substrate leveling effect more quickly, the embodiments of the present application provide a cerium oxide particle that can take into account both a high material removal rate and low grinding defects, as well as a particle dispersion and a leveling composition using the cerium oxide particles, a semiconductor device, and a leveling method for a substrate thereof.

[0046] Specifically, an embodiment of the present application provides a particle, which is a cerium oxide particle. The cerium oxide particle is a spherical or quasi-spherical particle with multiple protrusions formed on the surface. The spherical or quasi-spherical particle with multiple protrusions formed on the surface is composed of multiple grains, and the multiple grains include at least grains with a particle size greater than or equal to 15 nm.

[0047] The cerium oxide particles are spherical or quasi-spherical particles with multiple surface protrusions. The presence of these protrusions increases the material removal rate (MRR) of the cerium oxide particles against the substrate surface, resulting in a high abrasive performance. The multiple crystal grains comprising the cerium oxide particles include grains with a diameter of 15 nm or greater, which further enhances the MRR of the cerium oxide particles against the substrate. The spherical or quasi-spherical morphology ensures that when used as abrasive particles for planarizing substrates, the cerium oxide particles introduce minimal surface scratch defects. Therefore, these cerium oxide particles can achieve both a high MRR and low defectivity when used in chemical mechanical planarization processes.

[0048] In the present application, the spherical or quasi-spherical morphology of the cerium oxide particles can be known from their SEM photos or TEM photos. The cerium oxide particles are not polyhedrons with sharp edges. The cerium oxide particles are composed of multiple grains, that is, the cerium oxide particles are polycrystalline particles. Polycrystalline cerium oxide particles can also be known from their SEM photos or TEM photos. Specifically, each polycrystalline cerium oxide particle is a secondary particle composed of multiple single crystal grains; the polycrystalline particles have grain boundaries ("grain boundaries" are the interfaces between adjacent single crystal grains). Single crystal grains are primary particles and do not have grain boundaries inside. Among them, a protrusion on the surface of the above-mentioned cerium oxide particle can be at least a part of a single crystal grain.

[0049] The size of the average single crystal grains constituting the cerium oxide particles can be calculated based on the half-width of the (111) crystal plane diffraction peak in the X-ray Diffraction (XRD) spectrum of the cerium oxide particles, which has a particle size of more than 15 nm. If the size of the average single crystal grain is greater than 15 nm, then there must be grains with a particle size of more than 15 nm in the multiple crystal grains constituting the cerium oxide particles. Specifically, the diffraction information of the (111) crystal plane diffraction peak can be obtained from the XRD spectrum of the cerium oxide particles, such as the half-width, diffraction angle, etc. Based on this diffraction information, according to the Scherrer formula D = K×λ / (FWHM 111 ×cosθ 111 ) can be used to calculate the particle size of the above single crystal grains. Wherein, λ represents the wavelength of the X-ray used in the XRD test. For copper Kα rays, its wavelength λ is generally 0.154 nm. θ 111 In the XRD spectrum of cerium oxide particles, the diffraction peak of the (111) crystal plane corresponds to half the diffraction angle. 111 The half-maximum width (FWHM) of the (111) crystal plane diffraction peak of the cerium oxide particles is measured in radians. K is the Scherrer constant, K = 0.89. Of course, in other embodiments of the present application, the particle size of the above-mentioned crystal grains constituting the cerium oxide particles can also be obtained by other characterization methods (e.g., high-resolution electron microscopy).

[0050] Optionally, at least 50% or more of the plurality of crystal grains have a particle size greater than or equal to 15 nm. Furthermore, the number of crystal grains with a particle size greater than or equal to 15 nm in the plurality of crystal grains constituting a cerium oxide particle accounts for greater than 60%, greater than 70%, greater than 80%, or greater than 90%, or even 100%.

[0051] In some embodiments of the present application, the multiple grains (i.e., single crystal grains) constituting the cerium oxide particles include at least grains with a particle size within the range of 15 nm to 50 nm. This not only effectively improves the removal rate of the cerium oxide particles from the substrate surface material, but also avoids scratches on the substrate surface after treatment due to oversized single crystal grains. Similarly, the number of grains with a particle size within the range of 15 nm to 50 nm in the multiple grains constituting a cerium oxide particle may be greater than 60%, greater than 70%, greater than 80%, or greater than 90%, or even 100%. In some cases, it can be said that the average particle size of the single crystal grains constituting the cerium oxide particles is within the range of 15 nm to 50 nm. For example, the particle size of the single crystal grains may be specifically 18 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, or 45 nm.

[0052] In the embodiment of the present application, the sphericity of the cerium oxide particles is in the range of 0.8-1.0. The higher particle sphericity can reflect that the spherical or quasi-spherical cerium oxide particles provided in the embodiment of the present application are closer to the standard sphere, and the substrate grinding defects caused by them are fewer. Among them, the sphericity of the particle is equal to the ratio of the projected area of the particle to the area of a perfect circle with the same circumference as the projected circumference of the particle. The sphericity of the particle SP = 4π × A / L 2 , A and L represent the projected area and projected perimeter of the cerium oxide particles measured from scanning or transmission electron micrographs, respectively. In some embodiments, the sphericity of the cerium oxide particles is between 0.85 and 1.0, or between 0.9 and 1.0, etc.

[0053] In the embodiments of the present application, the protrusions are not sharp protrusions. In other words, the protrusions are blunt protrusions. Blunt protrusions can help increase the material removal rate (MRR) of the cerium oxide particles on the substrate surface while preventing scratches on the treated substrate surface.

[0054] In an embodiment of the present application, the average width of the protrusions is greater than 10 nm. This may reflect that the protrusions are extensions present on the surface of the cerium oxide particles, and the presence of the protrusions can be more clearly observed; and protrusions of this width are not easy to fall off / break from the cerium oxide particle body and remain on the surface of the processed substrate. Among them, the width of the protrusion refers to the maximum value of the distance between any two points on the positive projection contour line of the protrusion on the cerium oxide particle body. In some embodiments of the present application, the average width of the protrusions is greater than 15 nm, greater than 20 nm, or greater than 30 nm, etc. In some embodiments of the present application, the width of each of the protrusions is greater than 10 nm, greater than 15 nm, greater than 20 nm, or greater than 30 nm, etc.

[0055] In an embodiment of the present application, the average height of the protrusions on the cerium oxide particles is greater than 5 nm. An appropriate average protrusion height can reflect that the protrusions are obvious extensions existing on the surface of the cerium oxide particles, so as to effectively improve the MRR of the cerium oxide particles to the substrate surface. The height of the protrusion refers to the distance between the end of the protrusion away from the body of the cerium oxide particle (i.e., the top) and the bottom of the protrusion. Exemplarily, the average height of the protrusion is greater than 10 nm, greater than 15 nm, greater than 20 nm, or greater than 30 nm. In some embodiments of the present application, the height of each of the protrusions is greater than 10 nm.

[0056] In some possible embodiments of the present application, in the cerium oxide particles, the spacing between adjacent protrusions is 0-20 nm. The spacing between adjacent protrusions is the minimum distance between the positive projection contour lines of adjacent protrusions on the cerium oxide particle body. When the spacing between adjacent protrusions is 0, it means that the two adjacent protrusions are in contact; when the spacing between adjacent protrusions is a non-zero value, it means that there is a gap between the two adjacent protrusions. The spacing between adjacent protrusions is within an appropriate range, which can reflect that the protrusions are arranged more closely, so that the above-mentioned cerium oxide particles with more protrusions on the surface have a larger contact area with the surface of the treated substrate, which is beneficial to the improvement of its MRR.

[0057] In the embodiments of the present application, the cerium oxide particles are dense particles. Specifically, the cerium oxide particles are free of pores. Because the cerium oxide particles are not simple aggregates of multiple single-crystal particles, but rather well-dispersed polycrystalline particles, the cerium oxide particles have no pores either inside or on their surfaces. This improves the structural stability of the cerium oxide particles and the efficiency of removing substrate surface material.

[0058] In some possible embodiments of the present application, the average number of protrusions within any 50 nm x 50 nm rectangular area on the surface of the cerium oxide particles is 3-30. This may reflect a high distribution density of protrusions on the surface of the cerium oxide particles. Thus, the cerium oxide particles with more protrusions on their surfaces have a larger contact area with the surface of the treated substrate, which facilitates an increased rate of removal of substrate surface material by the cerium oxide particles.

[0059] In an embodiment of the present application, the trivalent cerium in the cerium oxide particles accounts for more than 30% of the total amount of cerium elements. The higher trivalent cerium content in the cerium oxide particles can reflect a higher content of oxygen vacancies on its surface, and its grinding activity is correspondingly higher, thereby further improving its removal rate of the substrate material. Therefore, the cerium oxide particles are used in a chemical mechanical planarization process to achieve both a higher MRR and low defectivity. Exemplarily, the trivalent cerium in the cerium oxide particles can account for more than 32%, more than 35%, more than 40%, more than 45%, more than 50%, more than 55%, more than 60%, or even more than 65% of the total amount of cerium elements.

[0060] The ratio of trivalent cerium to the total cerium element in the cerium oxide particles can be obtained by UV-Raman spectroscopy of the cerium oxide particles. In the UV-Raman spectrum of the cerium oxide particles, the wave number at 595 cm -1 The Raman peaks near the wavelength are attributed to the vibration of intrinsic oxygen defects in CeO2, which can reflect the trivalent cerium content of cerium oxide. -1The Raman peaks nearby can be attributed to the symmetrical vibration of cerium and oxygen atoms in the cubic fluorite structure of CeO2, which can reflect the total content of all cerium elements in cerium oxide. The wave number is 595cm -1 The Raman peak near the wave number 465cm -1 The peak value ratio of the nearby Raman peaks can reflect the ratio of trivalent cerium to the total amount of cerium elements in the cerium oxide particles.

[0061] In some embodiments of the present application, the D50 particle size of the cerium oxide particles, as measured by dynamic light scattering, is within the range of 30 nm to 300 nm. This D50 particle size can be measured using a dynamic light scattering particle size analyzer (also known as a laser particle size analyzer). The D50 particle size represents the particle size value corresponding to the cumulative volume distribution percentage of the cerium oxide particles reaching 50%. Polycrystalline cerium oxide particles having a suitable D50 particle size are particularly suitable for surface planarization of substrates used in the manufacture of semiconductor devices. For example, the D50 particle size can be 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 140 nm, 160 nm, 180 nm, 200 nm, 220 nm, 240 nm, 260 nm, or 280 nm. In some embodiments, the D50 particle size is within the range of 50 nm to 190 nm.

[0062] In some embodiments of the present application, the D50, D90, and D10 particle sizes of the cerium oxide particles, as measured by dynamic light scattering, satisfy the following ratio: (D90 - D10) / D50 is less than 0.83. D10 and D90 represent the particle sizes corresponding to the 10% and 90% cumulative volume distribution percentages of the cerium oxide particles, respectively. D10, D50, and D90 are expressed in the same units (e.g., nanometers) and can be obtained from a particle size distribution plot of the cerium oxide particles measured using a dynamic light scattering particle size analyzer. (D90 - D10) / D50 reflects the dispersion of the cerium oxide particle size distribution. A smaller ratio indicates a higher particle size concentration and a narrower particle size distribution. For example, the (D90 - D10) / D50 ratio of the cerium oxide particles is less than 0.80, less than 0.75, or even less than 0.72.

[0063] In some embodiments of the present application, the specific surface area S of the cerium oxide particles can be in the range of 12-50 m 2 The specific surface area S of the cerium oxide particles can be measured using the nitrogen adsorption method (also known as the "BET method"). Because the cerium oxide particles provided in the embodiments of the present application have multiple protrusions integrally formed on their surfaces, their specific surface area is larger than that of smooth spheres of the same particle size. This increases the contact area with the substrate being treated, facilitating an increase in the substrate material removal rate.

[0064] In some possible embodiments of the present application, the roughness index RI of the cerium oxide particles is in the range of 1.5-4.5. The roughness index RI is the ratio of the average particle size of the cerium oxide particles measured based on an electron microscope photograph (which can be an SEM photograph or a TEM photograph, and the present application will be explained below using the SEM photograph as an example) to the theoretical average size (referred to as the SSA size) obtained by converting the specific surface area of the cerium oxide particles. For example, RI = SEM size / SSA size. Wherein, SSA size = 6 / (S × ρ); wherein S represents the specific surface area of the cerium oxide particles measured based on the nitrogen adsorption method, and the unit can be m 2 / g; ρ represents the density of cerium (IV) oxide, which is equal to 7.22 g / cm 3 Therefore, the SSA size in nm is equal to 0.83 / S×10 3 .

[0065] The spherical or quasi-spherical cerium oxide particles provided herein, each having a plurality of protrusions on its surface, have a suitably low roughness index (RI). This indicates that the specific surface area of the particles is suitably low for a given particle size. This reduces the likelihood of the particles agglomerating and causing scratches or other defects on the surface of the treated substrate. For example, the RI can be 2, 2.5, 3, 3.2, 3.5, 4, or 3.8.

[0066] In the embodiments of the present application, the cerium oxide particles do not contain carbon. That is, the carbon content of the cerium oxide particles is 0. The cerium oxide particles provided in the embodiments of the present application are sintered cerium oxide particles that do not contain organic matter, and therefore the carbon content of the particles is 0.

[0067] In some possible embodiments of the present application, a cerium source in which cerium accounts for greater than 99.9% of the total rare earth elements is used for the synthesis reaction, and the total content of cerium and oxygen in the resulting cerium oxide particles is greater than 99.9 wt %. Since the cerium oxide particles provided in the embodiments of the present application do not contain carbon and other additional metal elements, the total content of cerium and oxygen in the particles is relatively high, and the purity of the cerium oxide particles is relatively high. The cerium element refers to the sum of the contents of trivalent cerium and tetravalent cerium in the cerium oxide particles. In addition, it should be noted that the cerium oxide particles may also contain trace impurity elements (such as iron, lanthanum, etc.) derived from the cerium source itself used to prepare the cerium oxide particles. The mass ratio of cerium to total rare earth elements (including cerium and other impurity rare earth elements) in the cerium source is greater than 99.9%.

[0068] The present invention also provides a method for preparing the cerium oxide particles. The method may include the following steps:

[0069] (1) mixing an aqueous solution of an alkali, an aqueous solution of a water-soluble Ce(III) salt, and an acid to obtain a mixed solution; wherein the acid includes an inorganic acid and an organic acid;

[0070] (2) While maintaining the pH value of the mixed solution at greater than 8.0, heat-treating the mixed solution at a temperature below 100° C., collecting the obtained solid, and drying and calcining the solid at a high temperature to obtain the cerium oxide particles.

[0071] In the present application, a mixture of a water-soluble cerium salt, an inorganic acid, an organic acid, and an alkali is subjected to a heat treatment reaction at a temperature below 100°C while maintaining a pH value greater than 8.0, and the solid obtained by the reaction is calcined at a high temperature, so that the obtained cerium oxide particles are spherical or quasi-spherical polycrystalline particles with a plurality of protrusions integrally formed on the surface, and the particle size of the single crystal grains constituting the cerium oxide particles is above 15 nm, thereby ensuring that the oxide particles can better balance the high substrate material removal rate and low substrate defectivity when used in a chemical mechanical planarization process. In addition, the above-mentioned preparation method can also ensure that the average width, average height, and proportion of trivalent cerium to total cerium elements in the oxide particles are at the higher levels mentioned above in this application. The various characteristics of the oxide particles mentioned above in this application are all applicable to the cerium oxide particles obtained by this preparation method.

[0072] In step (1), the base includes one or more of ammonia water, alkali metal hydroxides (such as NaOH, KOH), secondary amines, tertiary amines, or quaternary amines. In some embodiments, the base is ammonia water. The water-soluble Ce(III) salt may include cerium nitrate, ammonium cerium nitrate, or a hydrated salt thereof. In some embodiments, the mixed solution in step (1) may also contain a water-soluble Ce(IV) salt.

[0073] In step (1), the mixing of the solutions can be carried out under an inert atmosphere (such as nitrogen, argon, helium, etc.) or in a sealed container after the air is replaced by an inert gas.

[0074] The inorganic acid may include at least one of nitric acid, sulfuric acid, phosphoric acid, etc. The organic acid may include substituted or unsubstituted C1-C 12 Alkyl carboxylic acid, C2-C 12 Alkenyl carboxylic acid, C2-C 12 At least one of alkynyl carboxylic acid or polycarboxylic acid. 12 Alkyl carboxylic acid refers to the number of carbon atoms in the alkyl group of the carboxylic acid. 12 Alkenyl carboxylic acid refers to the number of carbon atoms in the alkenyl group in the carboxylic acid. 12Alkynyl carboxylic acid refers to the number of carbon atoms of the alkynyl group in the carboxylic acid. The co-existence of an inorganic acid and an organic acid is beneficial to ensuring that the pH value of the reaction system is stable and promotes the formation of spherical or quasi-spherical particles. Among them, the acid can be added alone in the form of its own aqueous solution, or first added to an aqueous solution of a soluble Ce (III) salt and added in the form of a mixed aqueous solution containing acid and a soluble Ce (III) salt. In some embodiments of the present application, the ratio of the total number of carbon atoms to the number of carboxyl groups in the organic acid is between 2-4. The presence of the organic acid is thus more conducive to the formation of spherical or quasi-spherical cerium oxide particles, and spherical cerium oxide with obvious surface protrusions is obtained after high-temperature calcination. Exemplarily, the organic acid can be methacrylic acid, acrylic acid, butyric acid, adipic acid, etc.

[0075] In step (2), heat treatment is performed at a temperature below 100°C, mainly to form cerium oxide grains. In possible embodiments of the present application, the temperature of the heat treatment is 70-95°C, for example, specifically 76°C, 78°C, 80°C, 85°C, or 90°C. Further, in some embodiments of the present application, the temperature of the heat treatment is 76-95°C. Heat treatment of the above-mentioned mixed solution at a higher temperature in the presence of an organic acid is more conducive to ensuring that the majority of the cerium oxide particles obtained by the reaction are spherical, so that spherical or quasi-spherical cerium oxide particles with large protrusions on the surface can be obtained after subsequent high-temperature calcination.

[0076] In step (2), during the heat treatment, the pH of the mixed solution may change, for example, continuously decrease. However, the present application performs a heat treatment below 100°C while maintaining the pH value of the mixed solution greater than 8, which can ensure that the cerium oxide solid obtained by the heat treatment reaction can obtain cerium oxide particles with obvious protrusions when subsequently subjected to high-temperature calcination, and high-temperature calcination can trim the morphology of the cerium oxide particles, making the structure more rounded and dense, so that the cerium oxide particles can increase their flattening rate on the substrate without causing obvious surface defects on the substrate. In addition, performing the high-temperature calcination is also beneficial to ensure that the particle size of the single crystal grains constituting the polycrystalline cerium oxide particles is within a suitably large range (for example, above 15 nm as mentioned above) to improve the MRR.

[0077] The pH value of the mixed solution is maintained at greater than 8, which can be achieved by adding alkali during the heat treatment process or by adding an excess amount of alkali in step (1). It is understood that in step (1), the pH value of the mixed solution is greater than 8.0, for example, greater than or equal to 8.1, greater than or equal to 8.2, greater than or equal to 8.3, or greater than or equal to 8.5.

[0078] In some embodiments of the present application, in step (2), the solid after heat treatment is washed with water and then dried. Optionally, the pH of the solid is adjusted to between 3.5 and 6 after water washing. This can help improve the yield of cerium oxide material. The drying temperature can be 80-120°C. Optionally, the dried solid is pulverized and then calcined at high temperature. This can help improve the effect of high-temperature sintering. Optionally, in some embodiments of the present application, after the high-temperature calcination, the obtained cerium oxide powder can be mechanically dispersed. Exemplary mechanical dispersion can include but is not limited to dry ball milling, wet ball milling, sand milling, micro-jet homogenization, etc.

[0079] In a possible embodiment of the present application, in step (2), the temperature of the high temperature calcination may be 300-900°C. For example, the temperature of the high temperature calcination may be specifically 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, or 750°C, etc. In some embodiments, the temperature of the high temperature calcination is 500-800°C. In a possible embodiment of the present application, in step (2), the high temperature calcination may be carried out for 1-8 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, etc. Optionally, the high temperature calcination may be carried out under an inert atmosphere (such as nitrogen, argon, helium, etc.) to reduce Ce III Oxidation to Ce IV probability.

[0080] In some embodiments of the present application, the high-temperature calcination is performed in two or more stages. For example, in some examples, the first stage is to raise the temperature from room temperature to a first calcination temperature not exceeding 350°C, and maintain it at this temperature for 0.5-4 hours; the second stage is to continue raising the temperature from the first calcination temperature to a second calcination temperature not exceeding 900°C, and maintain it at this temperature for 1-8 hours. Optionally, the second calcination temperature is greater than 350°C, and can further be above 500°C.

[0081] The present embodiment further provides a particle dispersion, which includes the cerium oxide particles described above and a solvent.

[0082] In some embodiments of the present application, the solvent is water. In this case, the particle dispersion is specifically an aqueous dispersion of cerium oxide particles. In other embodiments of the present application, the solvent includes water and a water-soluble organic solvent. The water-soluble organic solvent should not cause precipitation or agglomeration of the cerium oxide particles. Exemplarily, the water-soluble organic solvent includes, but is not limited to, one or more of alcohols (such as methanol, ethanol, n-propanol, isopropanol, and n-hexanol), ketones (such as acetone and methyl ethyl ketone), esters (such as ethyl formate, propyl formate, ethyl acetate, methyl acetate, methyl lactate, butyl lactate, and ethyl lactate), and acids (such as acrylic acid and methacrylic acid). Furthermore, in the solvent, the mass of water is greater than the mass of the water-soluble organic solvent. Exemplarily, the mass ratio of water to the water-soluble organic solvent can be between 80 / 20 and 99 / 1.

[0083] In an embodiment of the present application, the pH of the particle dispersion is below 7. This is more conducive to the dispersion of the cerium oxide particles and is less likely to settle. In some embodiments, the pH of the particle dispersion is between 4 and 6.5.

[0084] In some possible embodiments of the present application, the mass percentage of cerium oxide particles in the particle dispersion is in the range of 1%-30%. In some embodiments, the mass percentage is 5%-15%. The particle dispersion has an appropriate solid content to facilitate its storage.

[0085] The embodiments of the present application further provide a planarization composition, which includes the cerium oxide particles described above in the embodiments of the present application, or includes the particle dispersion described above in the embodiments of the present application.

[0086] The flattening composition provided by the embodiment of the present application can be used for selectively removing material from the surface of a substrate to achieve flattening / flattening of the substrate surface. Wherein, flattening or flattening the substrate surface is a process of removing material from the substrate surface to form a roughly uniform, flat surface. Flattening can remove unwanted surface topography and surface defects, such as rough surfaces, agglomerated materials, lattice damage, scratches and contaminated layers or materials. In addition, flattening can also remove excess deposition materials deposited outside the holes when filling the holes in the substrate.

[0087] The planarization compositions provided in the embodiments of the present application can be used for chemical mechanical planarization of semiconductor substrates or glass substrates whose surface materials are silicon oxide, silicon carbide, or silicon nitride. For example, a semiconductor substrate may have a dielectric material (such as silicon oxide or silicon nitride) deposited thereon. The upper surface of the substrate may become uneven and require planarization / flattening.

[0088] The planarization composition provided in the present application contains the above-mentioned cerium oxide particles, which are spherical or quasi-spherical particles with multiple protrusions on the surface. This allows the planarization composition to remove substrate surface material at a faster rate and cause fewer substrate surface defects when used for planarization treatment of the substrate surface.

[0089] In some embodiments of the present application, at room temperature, the planarization composition has a removal rate of the silicon oxide film of greater than 1900 Å / min. In some embodiments, the removal rate is greater than 1940 Å / min, and further can be greater than 2000 Å / min.

[0090] In embodiments of the present application, the pH of the planarization composition is between 3 and 6, for example, 3, 3.5, 4, 4.5, 5, or 5.5. In some embodiments, the pH of the planarization composition is between 4.5 and 5.5. The appropriate pH of the planarization composition ensures good dispersion and a high content of cerium oxide particles therein, thereby achieving a good planarization effect.

[0091] It is understood that the planarization composition includes a pH adjuster. Exemplary pH adjusters may include one or more of nitric acid, phosphoric acid, acetic acid, ammonia water, sodium hydroxide, potassium hydroxide, and the like.

[0092] In some embodiments of the present application, the planarization composition further includes one or more additives such as a dispersant, a thickener, a flow improver, and a surfactant. These additives can be added as needed. Dispersants are used to improve the dispersibility of the cerium oxide particles and reduce the probability of sedimentation. For example, dispersants may include one or more of polyacrylic acid (PAA) and polyacrylamide. Thickeners and flow improvers are used to adjust the viscosity and fluidity of the planarization composition.

[0093] In some possible embodiments of the present application, the planarization composition contains cerium oxide particles at a concentration of 0.1wt% to 1wt%. This allows for a higher removal rate of silicon-containing dielectric layers, such as silicon oxide, by the planarization composition. For example, the cerium oxide particles may be present in the planarization composition at a concentration of 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.8wt%, or the like.

[0094] The embodiments of the present application also provide the use of the particle dispersion or planarization composition of the embodiments of the present application in planarization of a dielectric layer.

[0095] The dielectric layer may be a substrate for manufacturing a semiconductor device, or a dielectric layer on the surface of a substrate. In some embodiments of the present application, the dielectric layer may include a silicon dioxide layer, a silicon carbide layer, or a silicon nitride layer.

[0096] The present embodiment also provides a method for planarizing a substrate, comprising grinding the surface of the substrate using the planarizing composition of the present embodiment.

[0097] During the planarization process, the planarization composition can move relative to the substrate to grind the surface of the substrate. Figure 1 In some possible implementations of the present application, the surface of the substrate has a silicon oxide layer, a silicon carbide layer, or a silicon nitride layer.

[0098] By using the planarization composition of the embodiment of the present application to grind a substrate, the removal efficiency of unwanted materials on the substrate surface is high, and the surface of the substrate after treatment is smoother and has fewer surface defects.

[0099] The present application also provides a semiconductor device comprising a planarized substrate obtained using the planarization method described above. A functional layer for the semiconductor device can be formed on the planarized substrate, and the functional layer has a high bonding strength with the planarized substrate. Specifically, the semiconductor device can include a planarized substrate and a functional layer disposed on the planarized substrate. For example, the semiconductor device can include, but is not limited to, a chip.

[0100] The planarization, flattening, and chemical mechanical planarization involved in this application all refer to chemical mechanical polishing (CMP) technology.

[0101] The embodiments of the present application are further described below with reference to a number of embodiments.

[0102] Example 1

[0103] 2L of a 1.5M dilute ammonia solution was prepared using pure water and concentrated ammonia. 210g of commercially available cerium (III) nitrate hexahydrate was dissolved in a 30wt% aqueous nitric acid solution to obtain 160mL of a cerium salt mixture containing cerium nitrate and nitric acid, where the concentration of cerium nitrate was 3M. Under an inert atmosphere, the dilute ammonia solution, 5g of methacrylic acid, and the cerium salt mixture were mixed in a 3L reactor. The mixture was then heated to 80°C with stirring and maintained at 80°C for 4 hours. After cooling to room temperature, the pH of the resulting reaction solution was measured to be 8.3. The solid precipitate was collected from the resulting reaction solution, washed with pure water, and dried at 100°C. The solution was then calcined in a semi-enclosed muffle furnace (with an air outlet and a non-sealed door) without air flow. The temperature was first raised to 300°C and held for 1 hour, then raised to 650°C and held for 5 hours. The light yellow powder obtained after calcination was dispersed in pure water, and the pH was adjusted to 4.5 with nitric acid to obtain a dispersion of cerium oxide particles.

[0104] Preparation of the planarization composition: Polyacrylic acid (PAA) with a molecular weight of 4000 was added to the cerium oxide particle dispersion prepared in Example 1. The pH of the system was adjusted to 5.0 using ammonia and nitric acid to obtain a planarization composition containing 0.25 wt% cerium oxide particles, i.e., a polishing solution. The weight percentage of PAA in the planarization composition was 0.5 wt%.

[0105] The cerium oxide particle dispersion of Example 1 was analyzed using a dynamic light scattering particle size analyzer, and the hydrodynamic mean particle size (i.e., D50 particle size) of the cerium oxide particles was measured to be 143 nm. Furthermore, the ratio (D90 - D10) / D50 of the cerium oxide particles was measured to be 0.74.

[0106] The cerium oxide particle dispersion prepared in Example 1 was examined by scanning electron microscopy (SEM). The SEM images of the obtained cerium oxide particles are as follows: Figure 2 As shown. Figure 2 It can be seen that the cerium oxide particles are spherical or quasi-spherical in shape, with many blunt protrusions on the surface. From the SEM photos of more than 100 cerium oxide particles, 100 particles were randomly selected and the SEM particle size of each particle was measured. The average SEM particle size of the cerium oxide particles was calculated to be 123nm. In addition, the specific area of the cerium oxide particles measured by nitrogen adsorption method was 18m 2 According to the definition above in this application, the roughness index of the cerium oxide particles was measured to be 2.66.

[0107] The cerium oxide particle dispersion prepared in Example 1 was subjected to transmission electron microscopy (TEM) analysis, and the SEM photograph of the obtained cerium oxide particles was as follows: Figure 3 As shown. Figure 3It can be seen that the protrusions on the surface of the cerium oxide particles are integrally formed with the bulk of the particles; the width of the protrusions is generally greater than 10 nm, and the height is greater than 5 nm. The cerium oxide particles are relatively dense.

[0108] In addition, the cerium oxide particle dispersion prepared in Example 1 was subjected to Raman spectroscopy test, the excitation light was ultraviolet light, and the ultraviolet-Raman spectrum was obtained. The results are as follows: Figure 4 As shown. Figure 4 It can be seen that the wave number is 595cm -1 The peak of the Raman peak near the wave number 465 cm -1 The peak ratio of the nearby Raman peaks was 0.523, indicating that trivalent cerium accounted for 33.7% of the total cerium content in the cerium oxide particles. Furthermore, carbon-sulfur analyzer analysis revealed that the cerium oxide particles contained no carbon.

[0109] The cerium oxide particle dispersion prepared in Example 1 was centrifuged and dried to obtain dry cerium oxide particles. The cerium oxide particles were characterized by XRD. The obtained XRD spectrum was as follows: Figure 5 As shown. Figure 5 It can be seen that the half-maximum width of the (111) crystal plane diffraction peak is 0.365°, and the 2θ angle of the (111) crystal plane diffraction peak is 28.693°. According to the Scherrer formula, the corresponding single crystal grain size is calculated to be 22.2nm.

[0110] Planarization test: A polyurethane polishing pad was fixed to a planarization table. A planarization head, mounted with the substrate to be treated (specifically, a circular silicon wafer with a SiO2 film formed on its surface), was pressed against the polyurethane polishing pad at a pressure of 3 psi. The planarization table rotated at 60 rpm, and the planarization head rotated at 80 rpm. The planarization composition provided in Example 1 was supplied to the polishing pad at a flow rate of 100 mL / min. The substrate was planarized for 30 seconds. The planarization rate was calculated by dividing the difference in SiO2 film thickness before and after planarization by the planarization time. The substrate surface was then observed for scratches.

[0111] The planarization test was performed on the planarization composition provided in Example 1. It was found that the removal rate of the SiO2 film on the substrate surface was 2260 Å / min, and no obvious scratches were observed on the substrate surface.

[0112] Example 2

[0113] Prepare 500 mL of a 1.8M dilute ammonia solution using pure water and concentrated ammonia water. Dissolve 84 g of commercially available cerium (III) nitrate hexahydrate in a 30% nitric acid aqueous solution to obtain 160 mL of a 3M cerium nitrate solution. Under an inert atmosphere, add the above-mentioned dilute ammonia water, 1 g of methacrylic acid, and the cerium nitrate solution to a 1L reactor in sequence, heat to 85°C under stirring, and maintain the reaction at 85°C for 4 hours. During the reaction, when the pH of the system drops below 8.0, supplement with a 1.8M dilute ammonia solution. After cooling to room temperature, the pH of the resulting reaction mixture is detected to be 8.2. The solid precipitate from the reaction solution was collected, washed with pure water, and then dried at 100°C. The dried solid was then pulverized using a high-speed blender and calcined in a muffle furnace at 250°C for 0.5 hours in an air atmosphere, then at 300°C for 1 hour. The temperature was then raised to 720°C and calcined under a nitrogen atmosphere for 5 hours. The resulting powder was dispersed in pure water, and the pH was adjusted to 4.3 with nitric acid to produce a dispersion of cerium oxide particles.

[0114] The cerium oxide particle dispersion of Example 2 was measured using a dynamic light scattering particle size analyzer, and the D50 particle size of the cerium oxide particles was measured to be 182 nm; (D90-D10) / D50 was 0.64. The morphology of the cerium oxide particles of Example 2 was analyzed using an electron microscope, and the SEM photograph thereof is shown below. Figure 6 As shown. Figure 6 It can be seen that the cerium oxide particles are spherical or quasi-spherical in shape, with many blunt protrusions integrally formed on the surface. From the SEM photos of more than 100 cerium oxide particles, 100 particles were randomly selected and the SEM particle size of each particle was measured. The average SEM particle size of the cerium oxide particles was calculated to be 176nm. In addition, the specific area of the cerium oxide particles measured by nitrogen adsorption method was 16m 2 According to the definition above in this application, the roughness index of the cerium oxide particles was measured to be 3.39.

[0115] Furthermore, ultraviolet Raman spectroscopy revealed that trivalent cerium accounted for 34.5% of the total cerium content in the cerium oxide particles prepared in Example 2. A carbon-sulfur analyzer revealed that the cerium oxide particles contained no carbon. XRD revealed that the half-maximum width of the (111) diffraction peak of the cerium oxide particles prepared in Example 2 was 0.325°, and the 2θ angle was 28.673°. The corresponding single crystal particle size was calculated to be 24.95 nm using the Scherrer formula.

[0116] According to the method described in Example 1, a planarization composition was prepared using the cerium oxide particle dispersion of Example 2. The planarization composition was used to perform a planarization test on a circular silicon wafer having a SiO2 film formed on its surface. The removal rate of the SiO2 film was measured to be 2486Å / min, and no obvious scratches were observed on the surface of the silicon wafer.

[0117] Example 3

[0118] Prepare 3.2 L of 0.35 M dilute ammonia solution using pure water and concentrated ammonia. Dissolve 105 g of commercially available cerium (III) nitrate hexahydrate in a 30% nitric acid aqueous solution to obtain 160 mL of a 3 M cerium nitrate solution. In a sealed 5 L reactor, the dilute ammonia solution, 1.5 g of methacrylic acid, and the cerium nitrate solution were contacted and heated to 78°C with stirring. The reaction was then maintained at 78°C for 5 hours. After cooling to room temperature, the pH of the resulting reaction solution was measured to be 8.5. The solid precipitate in the reaction solution was collected, washed with pure water, and dried at 100°C. The solution was then heated to 300°C and calcined in a semi-enclosed muffle furnace with no air circulation for 1 hour, followed by further heating to 500°C and calcination for 5 hours. The resulting powder was dispersed in pure water and the pH adjusted to 5.0 with nitric acid to obtain a dispersion of cerium oxide particles.

[0119] The cerium oxide particle dispersion of Example 3 was measured using a dynamic light scattering particle size analyzer, and the D50 particle size of the cerium oxide particles was measured to be 80 nm; (D90-D10) / D50 was 0.76. The morphology of the cerium oxide particles of Example 3 was analyzed using an electron microscope, and the SEM photograph thereof is shown in FIG. Figure 7 As shown. Figure 7 It can be seen that the cerium oxide particles are spherical or quasi-spherical in shape, with many blunt protrusions integrally formed on the surface. From the SEM photos of more than 100 cerium oxide particles, 100 particles were randomly selected and the SEM particle size of each particle was measured. The average SEM particle size of the cerium oxide particles was calculated to be 78nm. In addition, the specific area of the cerium oxide particles measured by nitrogen adsorption method was 28m 2 According to the definition above in this application, the roughness index of the cerium oxide particles was measured to be 2.63.

[0120] In addition, ultraviolet Raman spectroscopy revealed that the trivalent cerium content in the cerium oxide particles prepared in Example 3 accounted for 44.3% of the total cerium content. A carbon-sulfur analyzer revealed that the cerium oxide particles prepared in Example 3 did not contain carbon. XRD analysis of the cerium oxide particles prepared in Example 2 revealed that the half-maximum width of the (111) crystal plane diffraction peak was 0.505° and the 2θ angle was 28.713°. The corresponding single crystal particle size was calculated to be 16.06 nm using the Scherrer formula.

[0121] According to the method described in Example 1, a planarization composition was prepared using the cerium oxide particle dispersion of Example 3. This planarization composition was used to perform a planarization test on a circular silicon wafer having a SiO2 film formed on its surface. The removal rate of the SiO2 film was measured to be 1944 Å / min, and no obvious scratches were observed on the surface of the silicon wafer.

[0122] Comparative Example 1

[0123] Comparative Example 1 differs from Example 1 in that high-temperature calcination is not performed. Specifically, after collecting the solid precipitate from the resulting reaction solution, the solid precipitate is washed with pure water until the conductivity of the washing solution is less than 100 μS / cm. The solid precipitate is then dispersed in pure water, and the pH is adjusted to 4.5 with nitric acid to obtain a dispersion of cerium oxide particles.

[0124] The cerium oxide particle dispersion of Comparative Example 1 was tested using a dynamic light scattering particle size analyzer, and the D50 particle size of the cerium oxide particles was measured to be 148 nm; (D90-D10) / D50 was 0.78.

[0125] The cerium oxide particle dispersion prepared in Comparative Example 1 was subjected to scanning electron microscopy (SEM) analysis, and the SEM photograph of the obtained cerium oxide particles was as follows: Figure 8 As shown. Figure 8 It can be seen that the cerium oxide particles are spherical or quasi-spherical in shape, with a rough surface composed of a large number of microcrystals with a width of less than 10 nm, and no obvious protrusions with a width greater than 10 nm. In addition, ultraviolet Raman detection showed that in the cerium oxide particles prepared in Comparative Example 1, trivalent cerium accounted for 65% of the total cerium element. The carbon element in the cerium oxide particles was 0.2% as determined by a carbon-sulfur analyzer. XRD detected that the half-maximum width of the (111) crystal plane diffraction peak of the cerium oxide particles prepared in Comparative Example 1 was 0.95°, and the 2θ angle was 28.560°. The particle size of the corresponding single crystal grains calculated according to the Scherrer formula was 8.53 nm, which is not within the range of 15-50 nm mentioned in this application.

[0126] In addition, from the SEM photos of more than 100 cerium oxide particles, 100 particles were randomly selected and the SEM particle size of each particle was measured. The average SEM particle size of the cerium oxide particles was calculated to be 132nm. In addition, the specific area of the cerium oxide particles was measured by nitrogen adsorption method to be 42m 2 According to the definition above, the roughness index of the cerium oxide particles was measured to be 6.67, which is greater than that of the cerium oxide particles in Example 1.

[0127] According to the method described in Example 1, a planarization composition was prepared using the cerium oxide particle dispersion of Comparative Example 1. The planarization composition was used to perform a planarization test on a circular silicon wafer having a SiO2 film formed on its surface. The removal rate of the SiO2 film was measured to be 1808Å / min, and obvious scratches were found on the surface of the substrate.

[0128] Comparative Example 2

[0129] The only difference between Comparative Example 2 and Example 2 is that no dilute ammonia solution was added during the reaction at 85°C.

[0130] The morphology of the cerium oxide particles prepared in Comparative Example 2 was analyzed using a scanning electron microscope. The SEM photographs thereof are shown in FIG. Figure 9 As shown, from Figure 9 It can be seen that a large number of polyhedral morphologies appear in the cerium oxide particles. The overall sphericity of the cerium oxide particles is poor, and the polyhedrons are mostly particles without obvious protrusions on the surface. In addition, the ultraviolet Raman method was used to detect that in the cerium oxide particles prepared in Comparative Example 2, trivalent cerium accounted for 31.6% of the total cerium element. The carbon-sulfur analyzer was used to detect that the cerium oxide particles did not contain carbon. XRD detected that the half-maximum width of the (111) crystal plane diffraction peak in the cerium oxide particles was 0.29°, and the 2θ angle was 28.635°. The particle size of the single crystal grains was calculated to be 27.96nm using the Scherrer formula.

[0131] According to the method described in Example 1, a planarization composition was prepared using the cerium oxide particle dispersion of Comparative Example 2. The planarization composition was used to perform a planarization test on a circular silicon wafer having a SiO2 film formed on its surface. The removal rate of the SiO2 film was measured to be 1708Å / min, and obvious scratches were found on the surface of the substrate.

[0132] Comparative Example 3

[0133] The main difference between Comparative Example 3 and Example 1 is that no organic acid is introduced.

[0134] 0.4 L of 1.5 M dilute ammonia solution was prepared using pure water and concentrated ammonia. 54 g of commercially available hydrated cerium (III) nitrate was dissolved in a 30% aqueous nitric acid solution to obtain 160 mL of a 3 M cerium nitrate solution. Under an inert atmosphere, the dilute ammonia solution and cerium nitrate solution were added to a 1 L reactor. The reactor was sealed and heated to 80°C for approximately 4 hours. After cooling to room temperature, the pH of the resulting reaction mixture was measured to be 8.4. The solid precipitate in the reaction mixture was collected, washed with pure water, dried at 100°C, and then calcined in a semi-enclosed muffle furnace with no air flow, first at 300°C for 1 hour and then at 650°C for 5 hours. The resulting light yellow powder was dispersed in pure water, and the pH was adjusted to 4.5 with nitric acid to obtain a dispersion of cerium oxide particles.

[0135] The cerium oxide particle dispersion of Comparative Example 3 was tested using a dynamic light scattering particle size analyzer. The hydrodynamic average particle size (i.e., D50 particle size) of the cerium oxide particles was 80 nm, and (D90-D10) / D50 was 0.76. The morphology of the cerium oxide particles was analyzed using an electron microscope. The SEM image is shown below. Figure 10 As shown. Figure 10 It can be seen that the cerium oxide particles have a polyhedral morphology with no obvious surface protrusions. Furthermore, UV Raman spectroscopy revealed that the trivalent cerium content in the cerium oxide particles accounted for 22.0% of the total cerium element. XRD analysis revealed that the half-maximum width of the (111) diffraction peak of the cerium oxide particles prepared in Comparative Example 3 was 0.225°, and the 2θ angle was 28.547°. The corresponding single crystal particle size was calculated to be 36 nm using the Scherrer formula.

[0136] According to the method described in Example 1, a planarization composition was prepared using the cerium oxide particle dispersion of Comparative Example 3. The planarization composition was used to perform a planarization test on a circular silicon wafer having a SiO2 film formed on its surface. The removal rate of the SiO2 film was measured to be only 1441 Å / min, and no obvious scratches were observed on the surface of the silicon wafer.

[0137] The foregoing merely represents exemplary embodiments of the present application, and while the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0138] It should be understood that the first, second, and various numerical references used herein are merely distinctions for ease of description and are not intended to limit the scope of this application. In this application, "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0139] In the description of this application, unless otherwise specified, "multiple" means greater than or equal to two. "At least one" means one or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or plural.

[0140] In addition, the numerical range indicated by "-" in this application refers to the range that includes the numerical values recorded before and after the "-" as the minimum and maximum values, respectively. In this application, expressions about parameter ranges, such as "greater than or equal to (≥)", "less than or equal to (≤)", "above...", and "below..." all include the number itself. The numerical values and numerical ranges involved in the embodiments of this application are approximate values. Due to the influence of manufacturing processes / testing methods, etc., there may be a certain range of errors. Those skilled in the art can consider this part of the error to be negligible.

Claims

1. A particle, characterized in that The particles are cerium oxide particles, which are spherical or quasi-spherical particles. The surface of the spherical or quasi-spherical particles is formed with multiple protrusions, and the average width of the protrusions is greater than 10 nm. The spherical or quasi-spherical particles with multiple protrusions on the surface are composed of multiple grains, and the multiple grains include at least grains with a particle size in the range of 15 nm-50 nm. The ratio of the average particle size of the cerium oxide particles measured based on electron microscope photographs to the theoretical average size obtained based on the specific surface area of the cerium oxide particles is in the range of 1.5-4.

5.

2. The particle according to claim 1, wherein The sphericity of the cerium oxide particles is in the range of 0.8-1.

0.

3. The particle according to claim 1, wherein The average height of the protrusions is greater than 5 nm.

4. The particle according to claim 1, wherein The cerium oxide particles have no pores.

5. The particle according to claim 1, wherein The cerium oxide particles do not contain carbon element.

6. The particle according to any one of claims 1 to 5, characterized in that The trivalent cerium in the cerium oxide particles accounts for more than 30% of the total cerium element.

7. The particle according to any one of claims 1 to 5, characterized in that The D50 particle size of the cerium oxide particles measured based on dynamic light scattering is in the range of 30 nm to 300 nm.

8. The particle according to any one of claims 1 to 5, characterized in that The D50 particle size, D90 particle size, and D10 particle size of the cerium oxide particles measured by dynamic light scattering method satisfy the following: (D90-D10) / D50 is less than 0.

83.

9. The particle according to any one of claims 1 to 5, characterized in that The specific surface area of the cerium oxide particles is 12-50 m 2 / g.

10. A particle dispersion, characterized in that: The method comprises the particles according to any one of claims 1 to 9 and a solvent.

11. The particle dispersion according to claim 10, wherein The solvent includes water, or includes water and a water-soluble organic solvent.

12. A planarization composition, characterized in that: The method comprises the particles according to any one of claims 1 to 9, or the particle dispersion according to any one of claims 10 to 11.

13. The planarization composition according to claim 12, wherein The pH of the planarizing composition is between 3 and 6.

14. The planarization composition according to claim 12, wherein The leveling composition further comprises one or more of a pH adjuster, a dispersant, a thickener, a flow improver, and a surfactant.

15. The planarization composition according to any one of claims 12 to 14, characterized in that: In the planarization composition, the content of the cerium oxide particles is 0.1-1 wt %.

16. Use of the particle dispersion according to any one of claims 10 to 11, or the planarization composition according to any one of claims 12 to 15, in planarizing a dielectric layer.

17. The use according to claim 16, characterized in that The dielectric layer includes one or more of a silicon oxide layer, a silicon carbide layer, or a silicon nitride layer.

18. A method for planarizing a substrate, characterized in that: The method comprises grinding the surface of the substrate using the planarizing composition according to any one of claims 12 to 15.

19. A semiconductor device, characterized in that: It comprises a planarized substrate obtained by the planarization method according to claim 18.

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