Electrochemical mechanical polishing composition, use and method

Abstract

The present application relates to the technical field of polishing processing. Provided are an electrochemical mechanical polishing composition, the use and a method. The electrochemical mechanical polishing composition comprises a liquid carrier, a pH regulator, an organic electrolyte and chamfered octahedral cerium oxide abrasive particles, wherein the chamfered octahedral cerium oxide abrasive particles are dispersed in the liquid carrier. The ratio of the cumulative volume of abrasive particles having a particle size of two times of or higher than the average particle size measured by means of a scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles to the cumulative volume of abrasive particles having a particle size of or lower than the average particle size measured by means of the scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles is at least 0.1.

Description

Electrochemical mechanical polishing composition, use and method Technical Field

[0001] The present application relates to the technical field of polishing processing, and in particular to an electrochemical mechanical polishing composition, use and method. Background Art

[0002] As a third-generation semiconductor material, silicon carbide has broad application scenarios in aerospace, new energy vehicles, consumer electronics, and other fields. However, due to its high hardness and high stability, silicon carbide is difficult to polish, resulting in low polishing efficiency and extremely low material removal rates.

[0003] Currently, the primary polishing method for silicon carbide (SiC) is chemical mechanical polishing (CMP). CMP combines the physical abrasive action of nanoparticles with the chemical etching action of a polishing solution to smooth and flatten the SiC surface. The primary rate-limiting step in current CMP polishing is the oxidation of the SiC surface. To achieve higher material removal rates, a new polishing method and polishing composition are needed to increase the oxidation rate of SiC surfaces. Summary of the Invention

[0004] Based on the above problems, the present application provides an electrochemical mechanical polishing composition, use and method, which uses cut-corner octahedral cerium oxide abrasives to electrochemically mechanically polish silicon carbide materials to improve the oxidation rate and mechanical polishing rate of silicon carbide materials, thereby achieving high-efficiency and high-quality polishing of silicon carbide materials.

[0005] To achieve the above objectives, the embodiments of the present application adopt the following technical solutions:

[0006] In the first aspect, the present application provides an electrochemical mechanical polishing composition comprising a liquid carrier, a pH regulator, an organic electrolyte, and cut-off octahedral cerium oxide abrasive particles, wherein the cut-off octahedral cerium oxide abrasive particles are dispersed in the liquid carrier, wherein the ratio of the cumulative volume of abrasive particles in the cut-off octahedral cerium oxide abrasive particles having a diameter greater than twice the average particle size measured by a scanning electron microscope to the cumulative volume of abrasive particles in the cut-off octahedral cerium oxide abrasive particles having a diameter less than the average particle size measured by a scanning electron microscope is at least 0.1.

[0007] In some embodiments, the pH value of the electrochemical mechanical polishing composition is 2-7.

[0008] In some embodiments, the cut-corner octahedral cerium oxide abrasive particles have a zeta potential of at least 10 mV at a pH of 3.5-4.5 in the electrochemical mechanical polishing composition.

[0009] In some embodiments, the electrochemical mechanical polishing composition has a conductivity of at least 1 mS / cm at a pH of 3.5-4.5.

[0010] In some embodiments, the pH adjuster comprises an organic acid.

[0011] In some embodiments, the organic electrolyte includes an organic monoacid salt.

[0012] In some embodiments, the organic monoacid salt is at least one of isonicotinate, glycolate, hydroxypropionate, butyrate, isobutyrate, butyrate, propionate, acetate, valerate, sorbate, and propiolate.

[0013] In some embodiments, the coefficient of variation of the average particle size of the chamfered octahedral cerium oxide abrasive particles measured by scanning electron microscopy is greater than 30%.

[0014] In some embodiments, the chamfered octahedral cerium oxide abrasive particles have a non-monodisperse particle size distribution as measured by scanning electron microscopy.

[0015] In some embodiments, the chamfered octahedral cerium oxide abrasive particles have a polydispersity index of at least 0.1 as measured by scanning electron microscopy.

[0016] In some embodiments, at least 0.5% of the cut-corner octahedral cerium oxide abrasive grains have a particle size greater than twice the average particle size as measured by a scanning electron microscope.

[0017] In some embodiments, the average particle size of the cut-off octahedral cerium oxide abrasive particles measured by scanning electron microscopy is 20 nm to 100 nm.

[0018] In some embodiments, the chamfered octahedral cerium oxide abrasive particles include calcined chamfered octahedral cerium oxide sol.

[0019] In a second aspect, the present application provides a use of an electrochemical mechanical polishing composition, wherein the electrochemical mechanical polishing composition as described in any one of the first aspects is used for electrochemical mechanical polishing of silicon carbide materials.

[0020] In a third aspect, the present application provides a method for electrochemical mechanical polishing of a silicon carbide material, comprising the following steps:

[0021] (1) preparing an electrochemical mechanical polishing composition as described in any one of the first aspects above and placing it on a polishing pad;

[0022] (2) placing a working electrode and a counter electrode in the electrochemical mechanical polishing composition so that the working electrode and the counter electrode are in contact with the electrochemical mechanical polishing composition, and applying a current between the working electrode and the counter electrode to perform an electrochemical oxidation reaction on the surface of the silicon carbide material to form a silicon oxide layer, wherein the working electrode is the silicon carbide material bonded to the lower surface of the polishing head;

[0023] (3) The corner-cut octahedral cerium oxide abrasive is dispersed in the electrochemical mechanical polishing composition, the silicon carbide material is brought into contact with the polishing pad, and the polishing head and the polishing pad are moved to polish the silicon oxide layer.

[0024] Through the above technical solution, the silicon carbide material is polished by adopting the electrochemical mechanical polishing method, the oxidation rate and mechanical polishing rate of the silicon carbide material surface are improved, and the surface and subsurface damage of the silicon carbide material are reduced, thereby achieving high-efficiency and high-quality polishing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] FIG1 shows a SEM image of uncalcined truncated octahedral cerium oxide provided according to an embodiment of the present specification;

[0027] FIG2 shows a SEM image of calcined truncated octahedral cerium oxide provided according to an example of the present specification.

[0028] FIG3 shows a SEM image of uncalcined truncated octahedral cerium oxide (purchased) provided according to a comparative example of the present specification. DETAILED DESCRIPTION

[0029] The following description provides specific application scenarios and requirements for this specification, with the goal of enabling those skilled in the art to make and use the contents of this specification. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but is intended to be accorded the broadest scope consistent with the claims.

[0030] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. For example, as used herein, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. When used in this specification, the terms "comprise," "include," and / or "contain" are intended to refer to the presence of the associated integers, steps, operations, elements, and / or components, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups or the addition of other features, integers, steps, operations, elements, components, and / or groups in the system / method.

[0031] As used herein, the term "substantially free of component X" refers to a composition that does not substantially contain the component X, i.e., the component may at most be present in the composition as an impurity or contaminant, but is not added to the composition as a separate component. This means that the component X is not added in a substantial amount.

[0032] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. In other words, X may include only any combination of A, B, and C, or may include any combination of A, B, and C as well as other possible contents / elements. The arbitrary combination of A, B, and C may be A, B, C, AB, AC, BC, or ABC.

[0033] As one of the most representative third-generation semiconductor materials, silicon carbide is widely used in many important fields such as IT, consumption, automobile, industry, aerospace, smart grid, rail transportation, power electronics, and shipbuilding.

[0034] Currently, the general process flow for processing silicon carbide materials is as follows: cutting, rough grinding, fine grinding, rough polishing (mechanical polishing), and fine polishing (chemical mechanical polishing). For fine polishing, chemical mechanical polishing (CMP) is commonly used. CMP is a process that combines the physical grinding action of nanoparticles with the chemical corrosion action of a polishing liquid to smooth the surface of silicon carbide materials and achieve a highly flat surface. The main rate-limiting step in the CMP polishing method is the oxidation of the silicon carbide surface. In the prior art, strong oxidants such as potassium permanganate and hydrogen peroxide are commonly used to oxidize the silicon carbide surface to increase the oxidation rate of the silicon carbide surface. However, these strong oxidants pose problems during use, such as environmental pollution, contamination of polishing pads, and low oxidation efficiency.

[0035] In addition, the mechanical polishing of the silicon carbide surface oxide layer using aluminum oxide abrasives or diamond abrasives in the prior art generally causes surface and subsurface damage, which directly affects the quality of the silicon carbide material.

[0036] In view of this, the present application adopts electrochemical mechanical polishing (ECMP) to provide an electrochemical mechanical polishing composition, use and method, which can improve the surface oxidation rate of silicon carbide materials while improving the polishing quality, thereby achieving high-efficiency and high-quality polishing.

[0037] The composition is used for polishing silicon carbide materials. Depending on the close-packing of carbon and silicon atoms, the silicon carbide can form different crystalline structures, such as a cubic close-packed crystalline structure represented by 3C-silicon carbide, a hexagonal close-packed crystalline structure represented by 2H-silicon carbide, 4H-silicon carbide, and 6H-silicon carbide, and a rhombohedral close-packed crystalline structure represented by 15R-silicon carbide. The composition can be used to polish silicon carbide materials of any crystalline structure, without limitation.

[0038] The composition includes a liquid carrier, a pH regulator, an organic electrolyte, and abrasive particles. The pH regulator is used to adjust the pH value of the composition so that the composition can perform optimally during the polishing process. The organic electrolyte provides conductive ions to enhance the conductivity of the composition. The abrasive particles are used for polishing silicon carbide materials. The liquid carrier serves as a base for the composition and can accommodate a variety of components, such as a pH regulator, an organic electrolyte, and abrasive particles. The composition may also include chemical additives to enhance the interaction between the abrasive particles and the silicon carbide material. In addition, the composition may also include a biocide to inhibit or eliminate unwanted microorganisms in the composition.

[0039] The composition also includes one or more chemical additives. The chemical additives can interact with the cerium oxide abrasive and / or the silicon carbide material and / or the polishing pad during the ECMP process. The interaction can be based on, for example, hydrogen bonds, van der Waals forces, electrostatic forces, etc. The chemical additives can be suitable for use as, for example, removal rate promoters, polishing rate inhibitors, surfactants, thickeners, conditioning agents, complexing agents, chelating agents, biocides, dispersants, oxidants, film formers, etching inhibitors, catalysts, termination compounds, dissolution inhibitors, corrosion inhibitors, or any component of a combination thereof. Among them, electrolytes, pH regulators, polymers, amino acids, etc. can all be considered as chemical additives.

[0040] The liquid carrier can accommodate other components in the composition other than the liquid carrier, such as the abrasive, the pH regulator, the organic electrolyte, etc., so that these components are suspended in the liquid carrier and contacted with the material for polishing. The liquid carrier can be an aqueous carrier, and the liquid carrier can be any component suitable for suspending abrasive and chemical additives, for example, it can be one of water, ethers (such as dioxane and tetrahydrofuran), alcohols (such as methanol and ethanol), or it can be a combination of water, ethers (such as dioxane and tetrahydrofuran), alcohols (such as methanol and ethanol). When the liquid carrier is a combination of multiple components, the liquid carrier contains at least 50wt% water, for example, the aqueous carrier contains 50wt% water, 70wt% water, 90wt% water, 95wt% water, 99wt% water. Preferably, the liquid carrier is water. Further, the water is deionized water.

[0041] Abrasive particles, serving as the main substance for mechanical polishing, are dispersed in the liquid carrier. The abrasive particles may be at least one metal oxide abrasive selected from the group consisting of cerium oxide (ceria), aluminum oxide (aluminum oxide), silicon oxide (silicon dioxide), zirconium oxide (zirconium oxide), titanium oxide (titania), germanium oxide (germania), magnesium oxide (magnesium oxide), nickel oxide, gallium oxide (gallium oxide), and yttrium oxide (yttria).

[0042] Furthermore, the abrasive grains may be cerium oxide abrasive grains. Furthermore, the cerium oxide abrasive grains may be composed solely of cerium oxide abrasive grains, or may be a mixture of cerium oxide abrasive grains whose main component is cerium oxide. When the cerium oxide is an abrasive grain mixture, the cerium oxide content in the abrasive grain mixture is at least 72 wt%, for example, the abrasive grain mixture contains 72 wt%, 75 wt%, 78 wt%, 80 wt%, 83 wt%, 85 wt%, 89 wt%, 91 wt%, 93 wt%, 96 wt%, 98 wt%, or 100 wt% of cerium oxide. In addition to cerium oxide abrasive grains, the abrasive grain mixture may also include at least one metal oxide abrasive grain selected from aluminum oxide (aluminum oxide), silicon oxide (silicon dioxide), zirconium oxide (zirconium oxide), titanium oxide (titania), germanium oxide (germanium oxide), magnesium oxide (magnesium oxide), nickel oxide, gallium oxide (gallium oxide), and yttrium oxide (yttrium oxide). The cerium oxide abrasive grains in the composition are preferably cerium oxide abrasive grains comprising 100 wt% cerium oxide.

[0043] In some embodiments, the ceria abrasive particles are doped ceria abrasive particles. Suitable dopants are, for example, metal ions (such as Ca, Mg, Zn, Zr, Sc, Y) or lanthanides (such as lanthanum, praseodymium, neodymium, promethium, or samarium). However, it has been found that the abrasive particles of the present invention can exhibit high removal rates even in the absence of dopants. Therefore, the ceria abrasive particles are substantially free of dopants. Dopants may be present in the abrasive particles as impurities, which may originate from the raw materials or starting materials used to prepare the abrasive particles.

[0044] It should be noted that the cerium oxide abrasive may contain impurities, which are derived from the raw materials or processes for preparing the abrasive. It can be considered that these impurities are not part of the abrasive mixture, that is, these impurities are not added to the composition as a single component. This means that the impurities are not added in substantial amounts. The insubstantial amount of the present invention is less than 30 ppm, further less than 20 ppm, further less than 10 ppm, and further less than 1 ppm. Wherein, the ppm refers to ppm by weight. It should be noted that the cerium oxide abrasive in the composition is preferably cerium oxide abrasive without impurities. For the convenience of presentation, the following content will be described as cerium oxide abrasive with an abrasive content of 100 wt% and without impurities.

[0045] The cerium oxide abrasive particles should have a suitable morphology. The morphology of the cerium oxide abrasive particles affects the surface reactivity of the cerium oxide abrasive particles and affects the material removal rate. The morphology can be determined by a person skilled in the art, for example, using transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images.

[0046] In some embodiments, the cerium oxide abrasive particles may be chamfered octahedral cerium oxide abrasive particles. Specifically, the chamfered octahedral cerium oxide abrasive particles are in the form of chamfered octahedrons. The "chamfered octahedron" described in this application refers to a polyhedron, i.e., a polyhedron having 8 hexagonal faces and 6 square faces. Within the scope of this application, "chamfered octahedral cerium oxide" is not limited to the ideal truncated octahedral morphology, but also includes octahedra that have undergone morphological changes due to manufacturing processes or other factors. For example, chamfered octahedral cerium oxide abrasive particles may have more or less than 8 hexagonal faces, and / or more or less than 6 square faces. The hexagonal or square faces may have shape deviations (such as incomplete symmetry, irregular side lengths, or slight curvature). In some embodiments, the surface of the chamfered octahedral cerium oxide abrasive particles may exhibit a certain degree of concavity or deformation. Studies have found that chamfered octahedral cerium dioxide can achieve a high material removal rate on silicon carbide substrates while improving surface quality by reducing defects such as scratches.

[0047] The chamfered octahedral cerium oxide abrasive particles can be sol cerium oxide abrasive particles, i.e., cerium oxide abrasive particles prepared by a hydrolysis method or a sol-gel method. The sol cerium oxide abrasive particles can be obtained by a wet method, such as precipitation (e.g., precipitation synthesis of cerium oxide), hydrolysis-condensation reaction, or hydrothermal method.

[0048] Furthermore, the chamfered octahedral cerium oxide abrasive particles may include at least one of uncalcined chamfered octahedral cerium oxide sol or calcined chamfered octahedral cerium oxide sol. In the present application, "non-calcined colloidal ceria" refers to cerium oxide sol particles that have not been calcined, that is, dispersed cerium oxide nanoparticles prepared directly by sol-gel method, hydrolysis method, precipitation method or similar wet process. "Post-calcined colloidal ceria" refers to cerium oxide particles after the above-mentioned cerium oxide sol particles have been calcined, that is, cerium oxide particles that are first prepared as cerium oxide sol and then calcined at high temperature to change their crystallinity, surface chemical properties, particle morphology or other physicochemical properties. Pure calcined cerium oxide (that is, cerium oxide that has not been synthesized by wet process) can provide a higher silicon dioxide removal rate than pure sol cerium oxide. However, pure calcined ceria typically has an irregular morphology with sharp edges, which can easily cause defects and lead to poor surface morphology. Research has found that by calcining sol ceria, the silicon carbide removal rate can be improved while still maintaining good surface morphology, thereby optimizing electrochemical mechanical polishing (ECMP) performance.

[0049] Figure 1 shows an SEM image of uncalcined chamfered octahedral cerium oxide provided according to an embodiment of the present specification; Figure 2 shows an SEM image of calcined chamfered octahedral cerium oxide provided according to an embodiment of the present specification; Figure 3 shows an SEM image of uncalcined chamfered octahedral cerium oxide (purchased) provided according to a comparative example of the present specification. As shown in Figures 1 and 2, the chamfered octahedral cerium oxide abrasive particles in the present application are polydisperse, that is, the size distribution of the particles in the chamfered octahedral cerium oxide abrasive particles is relatively wide. More preferably, the chamfered octahedral cerium oxide abrasive particles have a non-monodisperse particle size distribution, and the particle size distribution is measured by a scanning electron microscope. Studies have found that the non-monodisperse distribution can improve the removal rate of silicon carbide while reducing defects such as scratches.

[0050] All technical parameters based on scanning electron microscopy (SEM) in this application are based on the analysis of at least 1000 particles. Any SEM microscope applicable to the field and with appropriate resolution can be used for measurement.

[0051] The average particle size of the chamfered octahedral cerium oxide abrasive particles measured by scanning electron microscopy is 10 nm to 200 nm. In some embodiments, the average particle size of the chamfered octahedral cerium oxide abrasive particles measured by scanning electron microscopy is 20 nm to 100 nm. Furthermore, the average particle size of the cut-corner octahedral cerium oxide abrasive grains measured by scanning electron microscopy is 10 nm-20 nm, 20 nm-30 nm, 30 nm-40 nm, 40 nm-50 nm, 50 nm-60 nm, 60 nm-70 nm, 70 nm-80 nm, 80 nm-90 nm, 80 nm-90 nm, 90 nm-100 nm, 100 nm-110 nm, 110 nm-120 nm, 120 nm-130 nm, 130 nm-140 nm, 140 nm-150 nm, 150 nm-160 nm, 160 nm-170 nm, 170 nm-180 nm, 180 nm-190 nm, and 190 nm-200 nm. The average particle size refers to the arithmetic mean of the maximum distance between two points on the particle boundary.

[0052] The particle size distribution of the cut-corner octahedral cerium oxide abrasive can be described using the coefficient of variation (CV) of the average particle size measured by a scanning electron microscope. Furthermore, the coefficient of variation of the average particle size CV = (σ / μ) × 100%. Wherein, σ is the standard deviation of the average particle size, and μ is the average particle size measured by a scanning electron microscope. In the present embodiment, the coefficient of variation of the average particle size of the cut-corner octahedral cerium oxide abrasive measured by a scanning electron microscope is greater than 30%. Furthermore, the coefficient of variation of the average particle size of the cut-corner octahedral cerium oxide abrasive measured by a scanning electron microscope is greater than 31%, 32%, 33%, 34%, or 35%. It should be noted that the standard deviation of the average particle size and the coefficient of variation of the average particle size are determined by SEM. Studies have shown that the deformation coefficient of the average particle size of the present invention can improve the silicon carbide removal rate while reducing defects such as scratches.

[0053] The particle size distribution of cerium oxide abrasive grains can be described using the polydispersity index (PDI) measured by scanning electron microscopy. 2 / μ 2 . Wherein, σ is the standard deviation of the average particle size, and μ is the average particle size measured by a scanning electron microscope. It should be noted that there is an essential difference between the PDI measured by a scanning electron microscope (SEM) and the PDI measured by dynamic light scattering (DLS) or laser diffraction. In the present embodiment, the polydispersity index of the cut-off octahedral cerium oxide abrasive measured by a scanning electron microscope is at least 0.1. Furthermore, the polydispersity index of the cut-off octahedral cerium oxide abrasive measured by a scanning electron microscope is at least 0.105, 0.110, 0.115, or 0.120. It should be noted that the standard deviation of the average particle size and the polydispersity index are determined by SEM. Studies have found that the PDI of the present invention can improve the silicon carbide removal rate while reducing defects such as scratches.

[0054] During the polishing process, the particle size of the cerium oxide abrasive will affect the material removal rate of the cerium oxide abrasive on the substrate. Among them, the large-particle-size cerium oxide abrasive can enhance the material removal rate, while the smaller-particle-size cerium oxide abrasive can fill the gaps between the large-particle-size cerium oxide abrasive, thereby preventing the substrate material from generating surface defects due to the large-particle-size cerium oxide abrasive. In this embodiment, at least 0.5% of the chamfered octahedral cerium oxide abrasive has a particle size greater than twice the average particle size as measured by a scanning electron microscope. Furthermore, at least 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, or 1.7% of the chamfered octahedral cerium oxide abrasive has a particle size greater than twice the average particle size as measured by a scanning electron microscope.

[0055] In this embodiment, the ratio of the cumulative volume of abrasive particles having a diameter greater than or equal to twice the average particle size measured by a scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles to the cumulative volume of abrasive particles having a diameter less than or equal to the average particle size measured by a scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles is at least 0.1. Furthermore, the ratio of the cumulative volume of abrasive particles having a diameter greater than or equal to twice the average particle size measured by a scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles to the cumulative volume of abrasive particles having a diameter less than or equal to the average particle size measured by a scanning electron microscope in the chamfered octahedral cerium oxide abrasive particles is at least 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.46, or 0.50. Studies have found that the above-mentioned ratios can improve the silicon carbide removal rate while reducing defects such as scratches.

[0056] In some embodiments, the ceria abrasive particles may be ceria abrasive particles having at least one vertex, such as cubic ceria abrasive particles. Cubic ceria abrasive particles are ceria abrasive particles with a cubic crystal structure. Compared to traditional hexagonal ceria, cubic ceria has higher hardness, better chemical stability, and superior grinding performance, and can significantly improve the polishing efficiency of silicon carbide substrates.

[0057] There are many factors that affect the polishing rate of the cubic cerium oxide abrasive grains on the SiO2 molecular oxide layer, such as particle size, lattice parameters of the cubic cerium oxide abrasive grains, band gap of the cubic cerium oxide abrasive grains, F 2g Peak width, removal rate enhancer, etc. The particle size may include an average particle size and a particle size distribution width. If the average particle size is too large, a large number of defects, such as scratches and pits, may appear on the surface of the silicon carbide material; if the average particle size is too small, the material removal rate may be reduced. An appropriate particle size distribution can increase the abrasive packing density on the surface of the material (reduce the volume of the voids), thereby improving the material removal rate while avoiding the generation of a large number of scratches. The removal rate enhancer can enhance the interaction between the cubic cerium oxide abrasive and the material surface, thereby increasing the polishing rate of the cubic cerium oxide abrasive and thereby improving the removal rate.

[0058] As known to those skilled in the art, the average particle size can be obtained by laser diffraction measurement (e.g., using an LA-960 from Horiba). The graph obtained by such measurement provides the cumulative volume percentage of the cubic cerium oxide abrasive particles of a certain size. All particle sizes mentioned herein (e.g., D01, D30, D50, D70, D99, z-average particle size) refer to the particle size of the abrasive particles in the ECMP composition.

[0059] The Z-average particle size refers to the intensity-weighted average hydrodynamic size of a collection of particles measured by laser diffraction (e.g., using Horiba's LA-960). The z-average particle size measured by laser diffraction is different from the z-average particle size measured by electron microscopy as described above. The cubic cerium oxide abrasive has a suitable z-average particle size. A smaller z-average particle size will reduce the material removal rate. The cubic cerium oxide abrasive has a z-average particle size of at least 10 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive has a z-average particle size of 10 nm, 20 nm, 30 nm, 40 nm, 45 nm, or 50 nm as measured by laser diffraction. Further, the cubic cerium oxide abrasive has a z-average particle size of at least 50 nm as measured by laser diffraction. However, if the z-average particle size is too large, a large number of undesirable defects, such as scratches, will appear on the surface of the silicon carbide material during the ECMP process. The cubic cerium oxide abrasive particles have a z-average particle size of at most 500 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive particles have a z-average particle size of 500 nm, 450 nm, 400 nm, 350 nm, 300 nm, 250 nm, 200 nm, 180 nm, 130 nm, or 90 nm as measured by laser diffraction. Further, the cubic cerium oxide abrasive particles have a z-average particle size of at most 90 nm as measured by laser diffraction. In some embodiments, the cubic cerium oxide abrasive particles have a z-average particle size of 10 nm to 500 nm, 20 nm to 400 nm, 30 nm to 300 nm, 40 nm to 200 nm, 45 nm to 130 nm, or 50 nm to 90 nm as measured by laser diffraction.

[0060] D50 is the particle size at which 50% by volume of the cubic cerium oxide abrasive has a particle size less than the value. A smaller D50 will reduce the material removal rate. The cubic cerium oxide abrasive has a D50 of at least 5 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive has a D50 of 5 nm, 10 nm, 20 nm, 30 nm, 35 nm, 40 nm, or 45 nm as measured by laser diffraction. Further, the cubic cerium oxide abrasive has a D50 of at least 45 nm as measured by laser diffraction. However, if D50 is too large, a large number of undesirable defects, such as scratches, will appear on the surface of the silicon carbide material during ECMP processing. Therefore, the cubic cerium oxide abrasive should have a smaller average particle size. The cubic cerium oxide abrasive has a D50 of at most 400 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive has a D50 of 400 nm, 300 nm, 200 nm, 150 nm, 100 nm, 95 nm, or 90 nm as measured by laser diffraction. Further, the cubic ceria abrasive particles have a D50 of at most 90 nm as measured by laser diffraction. In some embodiments, the cubic ceria abrasive particles have a D50 of 5 nm to 400 nm, 10 nm to 300 nm, 20 nm to 200 nm, 30 nm to 150 nm, 35 nm to 100 nm, 40 nm to 95 nm, or 45 nm to 90 nm as measured by laser diffraction. It is generally believed that cubic ceria abrasive particles with a larger D50 will result in a higher material removal rate during ECMP processing. However, it was surprisingly found that the cubic ceria abrasive particles of the present invention can achieve a high material removal rate even with a smaller D50.

[0061] D01 is the particle size at which 1% by volume of the abrasive particles have a particle size less than the value. The cubic cerium oxide abrasive particles have a D01 of at least 2 nm, for example, 2 nm, 7 nm, 13 nm, 15 nm, 26 nm, or 28 nm, as measured by laser diffraction. A smaller D01 of the abrasive particles increases the packing density of the cubic cerium oxide abrasive particles on the surface of the silicon carbide material during ECMP treatment (reduces the void volume), which helps to improve the material removal rate. Further, the cubic cerium oxide abrasive particles have a D01 of at most 150 nm, for example, the cubic cerium oxide abrasive particles have a D01 of 150 nm, 120 nm, 100 nm, 90 nm, 80 nm, or 70 nm, as measured by laser diffraction. In some embodiments, the cubic cerium oxide abrasive particles have a D01 of 2 nm to 150 nm, 7 nm to 120 nm, 13 nm to 100 nm, 15 nm to 90 nm, 26 nm to 80 nm, or 28 nm to 70 nm, as measured by laser diffraction.

[0062] D30 is the particle size at which 30% by volume of the cubic cerium oxide abrasive has a particle size less than the value. Wherein, the cubic cerium oxide abrasive has a laser diffraction measurement of at least 3 nm, for example, the cubic cerium oxide abrasive has a laser diffraction measurement of 3 nm, 10 nm, 15 nm, 20 nm, 30 nm, 35 nm. A smaller D30 of the cubic cerium oxide abrasive increases the packing density of the cubic cerium oxide abrasive on the surface of the material during ECMP treatment (reduces the void volume), which helps to improve the material removal rate. Further, the cubic cerium oxide abrasive has a laser diffraction measurement of at most 350 nm, for example, the cubic cerium oxide abrasive has a laser diffraction measurement of 350 nm, 300 nm, 200 nm, 100 nm, 90 nm, 80 nm. In some embodiments, the cubic cerium oxide abrasive particles have a D30 measured by laser diffraction of 3 nm to 350 nm, 10 nm to 300 nm, 15 nm to 200 nm, 20 nm to 100 nm, 30 nm to 90 nm, or 35 nm to 80 nm.

[0063] D70 is the particle size at which 70% by volume of the cubic cerium oxide abrasive has a particle size less than the value. A higher D70 of the cubic cerium oxide abrasive increases the material removal rate during ECMP processing. The cubic cerium oxide abrasive has a D70 of at least 16 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive has a D70 of at least 16 nm, 18 nm, 24 nm, 30 nm, 40 nm, or 50 nm as measured by laser diffraction. However, if the D70 of the cubic cerium oxide abrasive is too high, more undesirable defects, such as scratches, will appear during ECMP processing. Therefore, the cubic cerium oxide abrasive has a D70 of at most 421 nm as measured by laser diffraction, for example, the cubic cerium oxide abrasive has a D70 of 421 nm, 376 nm, 269 nm, 218 nm, 194 nm, or 160 nm as measured by laser diffraction. In some embodiments, the cubic cerium oxide abrasive particles have a D70 measured by laser diffraction of 16 nm to 421 nm, 18 nm to 376 nm, 24 nm to 269 nm, 30 nm to 218 nm, 40 nm to 194 nm, or 50 nm to 160 nm.

[0064] D99 is the particle size at which 99% by volume of the cubic cerium oxide abrasive have a particle size less than the stated value. A higher D99 of the cubic cerium oxide abrasive increases the material removal rate during ECMP processing. The cubic cerium oxide abrasive has a laser diffraction measurement of at least 50 nm, for example, the cubic cerium oxide abrasive has a laser diffraction measurement of 50 nm, 70 nm, 80 nm, 90 nm, 100 nm. However, if the D99 of the cubic cerium oxide abrasive is too high, more undesirable defects, such as scratches, may occur during ECMP processing. Therefore, the cubic cerium oxide abrasive has a laser diffraction measurement of at most 730 nm, for example, the cubic cerium oxide abrasive has a laser diffraction measurement of 730 nm, 600 nm, 450 nm, 300 nm, 194 nm. In some embodiments, the cubic cerium oxide abrasive particles have a D99 of 70 nm to 600 nm, 80 nm to 450 nm, 90 nm to 300 nm, or 100 nm to 194 nm as measured by laser diffraction.

[0065] Generally, a wide particle size distribution results in higher material removal rates due to the greater number of larger cubic ceria abrasive particles and their improved loading during ECMP processing. However, a wide particle size distribution is often associated with a higher number of defects in the material surface. However, the cubic ceria abrasive particles of the present application can increase material removal rates even with a narrow particle size distribution.

[0066] The cubic cerium oxide abrasive should have a large steepness factor as described. The steepness factor used herein refers to the value obtained by the formula (D30 / D70)*100. D30 and D70 can be obtained by laser diffraction as described above. D30 is the particle size at which 30% by volume of the cubic cerium oxide abrasive has a particle size less than the value. D70 is the particle size at which 70% by volume of the cubic cerium oxide abrasive has a particle size less than the value. A wide particle size distribution provides a small steepness factor, while a narrow particle size distribution provides a large steepness factor. Among them, the cubic cerium oxide abrasive with a large steepness factor of the present invention exhibits a high material removal rate while achieving fewer defects in the material, such as scratches, during ECMP processing. Further, the cubic cerium oxide abrasive has a steepness factor of at least 34, for example, the cubic cerium oxide abrasive has a steepness factor of 34, 40, 45, 50, 60, 70, or 78. However, if the steepness factor is too large, the material removal rate during ECMP processing will be reduced. Therefore, the cubic cerium oxide abrasive grains have a steepness factor of at most 98, for example, the cubic cerium oxide abrasive grains have a steepness factor of 98, 97, 96, or 95.

[0067] The cubic cerium oxide abrasive should have a small slope factor. The term slope factor as used herein refers to the absolute value of the rising slope of the particle size distribution graph divided by the falling slope (meaning that its sign is not taken into account). As known to those skilled in the art, the particle size distribution graph can be obtained by particle size distribution measurement as described above, wherein the particle size (x-axis) is plotted relative to the volume percentage (y-axis) of the cubic cerium oxide abrasive. The term rising slope as used herein refers to the slope of the tangent (straight line) drawn from P_D01 to P_max. The term falling slope as used herein refers to the slope of the tangent (straight line) drawn from P_max to P_D99. P_D01 refers to the point in the particle size distribution graph where the particle size is equal to D01. D01 is the particle size obtained by laser diffraction as described above, and 1% by volume of the cubic cerium oxide abrasive has a particle size smaller than D01. P_D99 refers to the point in the particle size distribution graph where the particle size is equal to D99. D99 is the particle size obtained by laser diffraction as described above, and 99% by volume of the cubic cerium oxide abrasive has a particle size smaller than D99. P_max refers to the absolute maximum of the particle size distribution graph, i.e., the point in the particle size distribution graph having the maximum volume % of the cubic ceria abrasive. A smaller slope factor can, for example, be the result of a wider distribution of smaller cubic ceria abrasive particles than larger ceria abrasive particles, which can improve the packing of the cubic ceria abrasive particles during ECMP processing. It was found that a smaller slope factor results in fewer defects in the material while still exhibiting a high material removal rate. Further, the cubic ceria abrasive particles have a slope factor of up to 400, for example, the cubic ceria abrasive particles have slope factors of 400, 300, 200, 150, 90, 50, 30, 20, and 10.

[0068] During the synthesis of the cubic cerium oxide abrasive grains, crystallites are formed within the cubic cerium oxide abrasive grains. A crystallite can be a crystal or a region of a crystalline structure. A crystallite can be located anywhere within the cubic cerium oxide abrasive grain, such as at the center of the cubic cerium oxide abrasive grain or exposed on the surface of the cubic cerium oxide abrasive grain. One cubic cerium oxide abrasive grain can contain a single crystallite, two crystallites, or multiple crystallites. By controlling the conditions, such as temperature, during the synthesis of the cubic cerium oxide abrasive grains, a desired number and size of crystallites can be obtained within the cubic cerium oxide abrasive grains.

[0069] The cubic cerium oxide abrasive should have a high degree of crystallinity. The term crystallinity as used herein refers to the volume % of the cubic cerium oxide abrasive comprising crystallites. A suitable degree of crystallinity can be obtained by controlling parameters such as temperature during the synthesis of the cubic cerium oxide abrasive. As known to those skilled in the art, the degree of crystallinity can be obtained from a dry powder of the cubic cerium oxide abrasive by X-ray diffraction (XRD), for example, using a D8 X-ray diffractometer (Bruker Corp). It was found that a higher degree of crystallinity results in a higher material removal rate of the material during ECMP processing. Thus, the cubic cerium oxide abrasive has at least 56% by volume, for example, the cubic cerium oxide abrasive has a crystallinity of 56%, 78%, 86%, or 96% by volume of the cubic cerium oxide abrasive. In some embodiments, the cubic cerium oxide abrasive is a single crystallite.

[0070] The cubic cerium oxide abrasive should have a coefficient of linear thermal expansion (CTELP) with a suitable lattice parameter. CTELP refers to the expansion of the atomic spacing within the cubic cerium oxide abrasive in response to a specific temperature change. CTELP can be measured by X-ray diffraction (XRD), for example, using a D8 X-ray diffractometer (Bruker Corp) during multiple (such as at least four) heating and cooling cycles. As known to those skilled in the art, CTELP can be calculated from the slope of the curve of expansion relative to the average temperature of the heating and cooling cycles. CTELP refers to the average coefficient of linear thermal expansion in the temperature range of 20°C to 400°C. Surprisingly, it was found that a higher CTELP increases the material removal rate of the material during ECMP processing. Therefore, the cubic cerium oxide abrasive has at least For example, the cubic cerium oxide abrasive has a particle size of 40 nm. Further, the cubic cerium oxide abrasive has a particle size of at most 40nm. For example, the cubic cerium oxide abrasive grains have a particle size of 40 nm. In some embodiments, the cubic cerium oxide abrasive particles have a particle size of 40 nm. to to to CTELP.

[0071] The cubic cerium oxide abrasive particles may have lattice planes exposed on the surface of the abrasive particles, such as {100}, {110}, {111}, {220}, {422}, and combinations thereof. The desired lattice planes can be achieved, for example, by appropriate abrasive particle shape, abrasive particle size, and parameters (such as temperature) during the synthesis of the cubic cerium oxide abrasive particles. As known to those skilled in the art, lattice planes can be measured by X-ray diffraction, for example, using a D8 X-ray diffractometer (Bruker Corp) from a dry powder of the cubic cerium oxide abrasive particles. Compared to other lattice planes exposed on the surface of the cubic cerium oxide abrasive particles, such as {111} and {110}, the lattice plane {100} exposed on the surface of the cubic cerium oxide abrasive particles results in more oxygen vacancies. More oxygen vacancies on the surface of the cubic cerium oxide abrasive particles can increase the movement of oxygen atoms within the crystallites, which can increase the surface reactivity of the abrasive particles. It has been found that a higher percentage of lattice planes {100} exposed on the surface of the cubic cerium oxide abrasive particles can increase the material removal rate of the material during ECMP processing. In some embodiments, at least 26% of the crystal lattice planes exposed on the surface of the cubic cerium oxide abrasive grains, for example, 26%, 42%, 52%, 64%, 71%, 83%, or 94% of the crystal lattice planes exposed on the surface of the cubic cerium oxide abrasive grains are {100}. Furthermore, at least 94% of the crystal lattice planes exposed on the surface of the cubic cerium oxide abrasive grains are {100}.

[0072] The cubic cerium oxide abrasive grains should have a suitable lattice parameter a. The lattice parameter a refers to the average (arithmetic mean) length of the unit cells in the crystal lattice of the abrasive grains along the x-axis. As known to those skilled in the art, the lattice parameter can be obtained by X-ray diffraction, for example, using a D8 X-ray diffractometer (Bruker Corp), and by relative cos 2 The appropriate lattice parameter a can induce favorable mechanical stress in the abrasive grains. The cubic cerium oxide abrasive grains have at least The lattice parameter a of the cubic cerium oxide abrasive is, for example, The cubic cerium oxide abrasive grains have a lattice parameter a of at least The lattice parameter a of the cubic cerium oxide abrasive is, for example, The lattice parameter a.

[0073] The cubic cerium oxide abrasive grains have a low band gap E g As known to those skilled in the art, the band gap E g It refers to the minimum energy required to excite an electron from the valence band to the conduction band. gThe UV-Vis absorption spectrum of a 1 wt% solution of the abrasive grain can be obtained, for example, at 25°C using a Varian Cary 5E spectrophotometer (Agilent Technologies) with a scan wavelength of 300 to 1000 nm. Based on the UV-Vis absorption spectrum, a Tauc curve can be plotted as (αhν)2 (Y-axis) and (hγ) (X-axis), where α is the linear absorption coefficient, h is the Planck constant, and ν is the frequency of light. The linear portion of the graph can be extrapolated, and the intersection with the extrapolated X-axis corresponds to the band gap E. g . Smaller band gap E g This leads to increased formation of reactive oxygen species (ROS) such as superoxide, singlet oxygen, hydroxyl radicals, and hydrogen peroxide. ROS may contribute to higher surface reactivity during ECMP processing. A lower band gap E g This may be related to the higher material removal rate during ECMP processing. Therefore, the cubic cerium oxide abrasive grains have a band gap E of at most 3.40 eV. g For example, the cubic cerium oxide abrasive grains have band gaps of 3.40 eV, 3.34 eV, 3.31 eV, 3.27 eV, 3.20 eV, and 3.11 eV. Furthermore, the abrasive grains have a band gap E of at least 2.36 eV. g For example, the cubic cerium oxide abrasive grains have a band gap E of at least 2.36eV, 2.40eV, 2.46eV, 2.51eV, or 2.57eV. g The cubic cerium oxide abrasive grains have a band gap E of 2.36eV ​​to 3.40eV, 2.40eV to 3.34eV, 2.46eV to 3.31eV, 2.51eV to 3.27eV, and 2.57eV to 3.20eV. g . Smaller band gap E g This can be achieved through appropriate particle size distribution, particle morphology and microcrystalline structure of the abrasive particles.

[0074] The cubic cerium oxide abrasive grains have a narrow F value as evaluated by visible Raman spectroscopy. 2g Peak. Visible Raman spectra can be obtained, for example, at 25°C using a FRS27 Raman spectrometer (Bruker Corp) with a 532 nm laser on a dry powder of cubic cerium oxide abrasive grains. As known to those skilled in the art, F 2g The peak appears at 464 cm -1 and corresponds to Ce-O vibration. Raman spectra should be baseline corrected and normalized to F 2g The full width at half maximum (FWHM) can be used to describe the intensity of the F 2g The width of the peak at half its peak height. FWHM is F 2gThe peak intensity is equal to the wavelength difference at half the maximum intensity of the visible Raman spectrum measured at 532 nm. A smaller FWHM is associated with a larger crystallite size of the cubic cerium oxide abrasive. In addition, a smaller number of defect points will help reduce the FWHM. Crystal surface defects affect the oxygen mobility within the crystallite and change the surface reactivity during the ECMP process. Among them, a smaller FWHM can improve the removal rate of silicon carbide material. Therefore, the cubic cerium oxide abrasive has a FWHM of at most 58 cm-1 measured by Raman spectroscopy at a wavelength of 532 nm. -1 For example, the cubic cerium oxide abrasive grains have a FWHM of 58 cm-1 measured by Raman spectroscopy at a wavelength of 532 nm. -1 , 50cm -1 , 45cm -1 、42cm -1 , 40cm -1 , 35cm -1 , 30cm -1 , 28cm -1 , 25cm -1 , 20cm -1 , 15cm -1 , 13cm -1 , 11cm -1 F 2g peak.

[0075] The full width at 1 / 3 of the maximum peak (FWTM) can be used to describe the F below the peak. 2g The width of the peak. FWTM is F 2g The peak intensity is equal to the wavelength difference at 1 / 3 of the maximum intensity of the visible Raman spectrum measured at 532 nm. A smaller FWTM value is associated with a larger abrasive grain crystallite size and the presence of crystal surface defects. Among them, a smaller FWTM can improve the removal rate of silicon carbide material. Therefore, the cubic cerium oxide abrasive has a FWTM of at most 65 cm-1 measured by Raman spectroscopy at a wavelength of 532 nm. -1 For example, the cubic cerium oxide abrasive grains have a FWTM of at most 65 cm-1 measured by Raman spectroscopy at a wavelength of 532 nm. -1 、63cm -1 、60cm -1 , 55cm -1 , 50cm -1 , 45cm -1 , 40cm -1 , 35cm -1 , 30cm -1 , 25cm -1 , 23cm -1 , 21cm -1 F 2g peak.

[0076] The cubic cerium oxide abrasive grains should have a high D50 to FWHM ratio. The D50 to FWHM ratio is the absolute value of the D50 of the cubic cerium oxide abrasive grains divided by the FWHM of the cubic cerium oxide abrasive grains measured by Raman spectroscopy at a wavelength of 532 nm. 2g The absolute value of the FWHM of the peak. 2g The FWHM of the peak can be obtained as described above. A high ratio of D50 to FWHM is associated with a larger crystallite size relative to the abrasive grain size. A lower number of crystal defects also contributes to a higher D50 and FWHM ratio. 2g It has been found that D50 and F 2g A higher ratio of the FWHM of the peaks can be associated with an increased material removal rate of the material during ECMP processing. Thus, the cubic cerium oxide abrasive grains have a D50 of at least 4.51 and a F50 of at least 4.51 as measured by Raman spectroscopy at a wavelength of 532 nm. 2g For example, the cubic cerium oxide abrasive grains have a D50 of 4.51, 5.12, 5.72, 6.1, and 6.68 and a F50 of 532 nm measured by Raman spectroscopy. 2g The cubic cerium oxide abrasive grains should have a high D50 to FWTM ratio. The D50 to FWTM ratio is the absolute value of the D50 of the cubic cerium oxide abrasive grains divided by the FWHM of the cubic cerium oxide abrasive grains measured by Raman spectroscopy at a wavelength of 532 nm. 2g The D50 and FWTM of the cubic cerium oxide abrasive grains 2g The FWTM of the peak can be obtained as described above. 2g The higher the FWTM ratio of the peak is, the larger the crystallite size is relative to the abrasive particle size. The smaller number of crystal defects also helps to improve D50 and F 2g It has been found that D50 and F 2g A higher ratio of the FWTM of the peaks can be correlated with an increased material removal rate. Thus, the cubic cerium oxide abrasive grains have a D50 of at least 1.47, for example, the cubic cerium oxide abrasive grains have a D50 of 1.47, 2.15, 3.64, 3.95, 4.13, 4.81 and a F50 measured by Raman spectroscopy at a wavelength of 532 nm. 2g The ratio of the FWTM of the peak.

[0077] It should be noted that the cerium oxide abrasive can also have other forms, such as tetrahedron, triangular prism, dodecahedron, icosahedron, hexagonal pyramid, hexagonal prism, pentagonal prism, cone, tetrahedron, cuboid, rhombus, hexagonal rhombus and mixtures thereof, which will not be described in detail here.

[0078] There are many factors that lead to the aggregation and agglomeration of the cerium oxide abrasive particles, such as the content of the cerium oxide abrasive particles, the zeta potential of the cerium oxide abrasive particles, the viscosity of the composition, etc. Among them, the content of the cerium oxide abrasive particles in the composition is too high, the distance between the cerium oxide abrasive particles is too short, and the van der Waals attraction between them is much greater than their own gravity, so they attract each other and aggregate and agglomerate. The cerium oxide abrasive particles in the composition all carry the same type of charge, that is, the lower the charge density on the surface of the cerium oxide abrasive particles, the smaller the zeta potential, the weaker the charge repulsion between the abrasive particles, and the easier it is for the abrasive particles to condense. The higher the viscosity of the composition, the slower the movement of the cerium oxide abrasive particles in the composition, and the easier it is for the cerium oxide abrasive particles to aggregate and agglomerate.

[0079] Therefore, in order to avoid aggregation of the cerium oxide abrasive particles, the content of the cerium oxide abrasive particles in the composition is at least 0.001 wt% by weight, for example, the content of the cerium oxide abrasive particles in the composition is 0.001 wt%, 0.003 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 0.09 wt%, 0.12 wt%, or 0.14 wt%. The content of the cerium oxide abrasive particles in the composition is up to 21.7 wt% by weight, for example, the content of the cerium oxide abrasive particles in the composition is 21.7 wt%, 20.2 wt%, 19.8 wt%, 18.9 wt%, 17 wt%, 16.8 wt%, 16.5 wt%, 16 wt%, 15.5 wt%, 15 wt%, 14.5 wt%, 14 wt%, 13.3 wt%, 13 wt%, 12.5 wt%, 12 wt%, 11 wt%, 10.8 wt%. The range of the cerium oxide abrasive particles in the composition is 0.03 wt% to 18.9 wt% by weight. In some embodiments, the range of the cerium oxide abrasive in the composition is 0.003wt% to 15wt%, 0.05wt% to 12wt%, 0.09wt% to 10wt%, or 0.12wt% to 9wt%. Further, the range of the cerium oxide abrasive in the composition is between 0.03wt%-1wt%, 1wt%-5wt%, 5wt%-10wt%, 10wt%-15wt% or 15wt%-18.9wt%.

[0080] In addition, the charge density on the surface of the cerium oxide abrasive can be reflected by zeta potential. The zeta potential can be measured, for example, by a Mastersizer S (Malvern Instruments). As known to those skilled in the art, zeta potential refers to the potential at the interface between the mobile fluid in the composition and the fluid stabilization layer attached to the abrasive dispersed in the composition. The higher the zeta potential, the stronger the electrostatic repulsion between the cerium oxide abrasives and the better the stability of the composition. The zeta potential can be positive or negative, or even zero. There are many factors that affect the numerical value and positive or negative of the zeta potential, such as pH value, ion concentration, etc.

[0081] In the composition, the cerium oxide abrasive particles are positively charged, that is, the zeta potential of the cerium oxide abrasive particles is positive. For the cerium oxide abrasive particles with positive surface charge, the counter ions in the diffusion layer are negative. + ), the positive ion concentration in the electrolyte increases, and attracts the negative ions on the diffusion layer, and more positive ions are attracted into the inner layer, and more positive charges appear, which makes the absolute value of the zeta potential larger, the charge of the nano-abrasive particles increases, the repulsive force is enhanced, and it is more stable.

[0082] In order to increase the absolute value of the zeta potential, the pH value of the composition may be in the range of 2-7. In some embodiments, the pH value of the composition may be in the range of 3-6. In some embodiments, the pH value of the composition may be in the range of 3.5-5. Furthermore, the pH value of the composition may be in the range of 2-2.5, 2.5-3, 3-3.5, 3.5-4, 4-4.5, 4.5-5, 5-5.5, 5.5-6, 6-6.5, or 6.5-7.

[0083] In order to achieve better removal and polishing effect, the cerium oxide abrasive has a zeta potential of at least 10 mV when the pH value of the composition is 3.5-4.5, such as 10 mV, 11 mV, 12 mV, 13 mV, 14 mV, 15 mV, 16 mV, 17 mV, 18 mV, 19 mV, 20 mV, 21 mV, 22 mV, 23 mV, 24 mV, 25 mV, 26 mV, 27 mV, 28 mV, 29 mV, 30 mV, 31 mV, 32 mV, 33 mV, 34 mV, etc. The cerium oxide abrasive particles have a zeta potential of up to 80 mV at a pH of the composition of 3.5-4.5, such as 80 mV, 75 mV, 70 mV, 65 mV, 60 mV, 55 mV, 50 mV, 45 mV, 40 mV, 35 mV, etc. The cerium oxide abrasive particles have a zeta potential of 25 to 80 mV, 11 to 75 mV, 35 to 75 mV, 21 to 70 mV, 16 to 65 mV, 45 to 65 mV, 26 to 60 mV, 15 to 55 mV, 34 to 55 mV, 27 to 50 mV, 30 to 45 mV, 18 to 40 mV, 11 to 35 mV, 23 to 35 mV, 15 to 30 mV, 12 to 25 mV, 17 to 25 mV, 12 to 20 mV, etc., at a pH of the composition of 3.5-4.5.

[0084] It should be noted that the above pH values ​​are only examples of the relationship between pH value and zeta potential, and the relationship between pH value and zeta potential in this application is not limited to the above case. The two can be any combination of the above pH value ranges and zeta potential ranges. For example, the cerium oxide abrasive has a zeta potential of at least 10 mV when the pH value of the composition is 2-7, and the cerium oxide abrasive has a zeta potential of at most 80 mV when the pH value of the composition is 2-7; the cerium oxide abrasive has a zeta potential of 15 mV-75 mV when the pH value of the composition is 3-6; the cerium oxide abrasive has a zeta potential of 28 mV-60 mV when the pH value of the composition is 3.5-5, and so on. No examples are listed here one by one.

[0085] The composition further includes a pH adjuster to adjust the pH value so that the zeta potential of the composition is within a suitable value or range. The pH adjuster can be an acid. Furthermore, the acid can be an organic acid.

[0086] The organic acid includes at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, methylbutyric acid, hexanoic acid, dimethylbutyric acid, ethylbutyric acid, methylvaleric acid, heptanoic acid, methylhexanoic acid, octanoic acid, ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, malic acid, phthalic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, furancarboxylic acid, tetrahydrofuranic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, methanesulfonic acid, ethanesulfonic acid, sulfosuccinic acid, benzenesulfonic acid, toluenesulfonic acid, phenylphosphonic acid or hydroxyethyldiphosphonic acid.

[0087] Furthermore, the organic acid includes at least one of maleic acid, malic acid, tartaric acid, citric acid, acetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid or pimelic acid.

[0088] Regarding inorganic acids, the composition of the present invention does not contain any. In the prior art, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid are commonly used as pH adjusters. However, these inorganic acid pH adjusters can react with the cerium oxide abrasive and the surface of the polishing material, thereby reducing the removal rate of the composition. Therefore, the present invention does not contain any inorganic acids.

[0089] In addition, the composition further includes a pH buffering agent, which is used to help maintain a suitable pH value for the composition. The pH buffering agent can be any suitable buffering agent. For example, the pH buffering agent can include at least one of a phosphate, sulfate, acetate, borate, and ammonium salt.

[0090] The composition also includes a water-soluble polymer. The water-soluble polymer may be a homopolymer, a copolymer or a combination thereof. The water-soluble polymer may be neutral in the composition, may be positively charged or negatively charged. It should be noted that the term "water-soluble" as used herein refers to a polymer having a solubility of at least 0.1 mg / ml in water at 25°C. Furthermore, the water-soluble polymer may be freely soluble in water at 25°C. The water-soluble polymer may be polyvinyl pyrrolidone, polyvinyl acetamide, polyglycerol, polyethylene glycol (PEG), polypropylene glycol (PPG), polytetramethylene glycol (PTMG), polytetramethylene ether glycol (PTMEG), functionalized PEG, hydrophobically modified PEG, polyethylene oxide, polyethylene glycol (PEG)-polypropylene glycol (PPG) block copolymer, polyether polyol copolymer, fatty alcohol alkoxylate, end-capped fatty alcohol alkoxylate, alkylene oxide ethylenediamine adduct, polyethyloxazoline, polycarboxylic acid (such as polypropylene glycol), polyols such as polyethylene glycol ...ols such as polyethylene glycol, polyethylene glycol (PEG)-polypropylene glycol (PPG) block copolymer, polyols such as polyethylene glycol, polyethylene glycol (PEG)-polypropylene glycol (PPG) block copolymer, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol, polyols such as polyethylene glycol The water-soluble polymer is preferably selected from the group consisting of polyols, polyols, polystyrene sulfonic acid, polyvinyl alcohol, polyvinyl pyrrolidone, sorbitan monooleate, oxyalkylene polymers, poly(hydroxyethyl methacrylate), poly(hydroxyethyl methacrylate), copolymers of poly(hydroxyethyl methacrylate), copolymers of poly(hydroxyethyl methacrylate), polysaccharides, cellulose derivatives (such as hydroxypropyl cellulose, hydroxyethyl cellulose), methacryloyloxyethyltrimethylammonium, and synthetic polymers (such as xanthan gum and sodium alginate). Further, the water-soluble polymer is a nonionic homopolymer. Further, the water-soluble nonionic homopolymer is a polyether.

[0091] The water-soluble polymer should have a suitable molecular weight (MW). The molecular weight of the water-soluble polymer used herein refers to the weight average molecular weight of the water-soluble polymer. Further, the water-soluble polymer has a molecular weight of at least 10g / mol, such as a water-soluble polymer having a molecular weight of 10g / mol, 20g / mol, 40g / mol, 60g / mol, 80g / mol. It has been found that high molecular weight water-soluble polymers can reduce the material removal rate during ECMP treatment. It has been surprisingly found that low molecular weight water-soluble polymers can achieve fewer defects on the material surface while achieving high silicon carbide material removal rate during ECMP treatment. Therefore, the water-soluble polymer has a molecular weight of at most 17,000g / mol, such as a water-soluble polymer having a molecular weight of 17,000g / mol, 13,000g / mol, 10,000g / mol, 7,500g / mol, 5,000g / mol, 4,000g / mol. In some embodiments, the water-soluble polymer has a molecular weight of 10 g / mol to 17,000 g / mol, 20 g / mol to 13,000 g / mol, 40 g / mol to 10,000 g / mol, 60 g / mol to 75,000 g / mol, or 80 g / mol to 5,000 g / mol.

[0092] When used, the composition contains at least 0.0001 wt% of a water-soluble polymer, such as the composition contains 0.0001 wt%, 0.001 wt%, 0.007 wt%, 0.013 wt%, 0.021 wt% of a water-soluble polymer. However, the amount of water-soluble polymer should not be too high because it will reduce the removal rate of the silicon carbide material. Therefore, when used, the composition contains up to 9.7 wt% of a water-soluble polymer, such as the composition contains 9.7 wt%, 4.4 wt%, 2.3 wt%, 1.2 wt%, 0.14 wt% of a water-soluble polymer. In some embodiments, when used, the composition contains 0.0001 wt% to 9.7 wt%, 0.001 wt% to 4.4 wt%, 0.007 wt% to 2.3 wt%, 0.013 wt% to 1.2 wt% of a water-soluble polymer.

[0093] The composition should have a suitable viscosity. The viscosity can be measured in mPa*s (milliPascal seconds) at 25°C using an NDJ-8S viscometer (Shanghai Lichen Instrument Technology Co., Ltd.). Higher viscosity can reduce the aggregation and agglomeration of abrasive particles, thereby achieving fewer defects in the material. The composition has a viscosity of at least 0.08 mPa*s, such as 0.08 mPa*s, 0.24 mPa*s, and 0.72 mPa*s when measured as a 2% solution at 25°C. However, if the viscosity is too high, the movement of abrasive particles and other components other than abrasive particles in the composition will be restricted, and the CeO2 abrasive particles will be more likely to aggregate and agglomerate, resulting in a reduced removal rate. Therefore, the composition has a viscosity of at most 28.3 mPa*s when measured as a 2% solution at 25°C, for example, the composition has a viscosity of 28.3 mPa*s, 15.3 mPa*s, and 7.8 mPa*s when measured as a 2% solution at 25°C.

[0094] In addition to polishing quality, polishing efficiency is also a major factor affecting the effect of electrochemical mechanical polishing. In this application, the electrochemical mechanical polishing process is mainly divided into two steps. The first is electrochemical anodic oxidation, that is, the surface of the silicon carbide material is oxidized to form a SiO2 molecular oxide layer; the second is that cerium oxide abrasives mechanically polish the SiO2 molecular oxide layer, that is, there are oxygen vacancies on the surface of the cerium oxide abrasive, which can form Ce-O-Si bonds with the SiO2 molecules produced by oxidation and weaken the Si-O-Si bonds between the SiO2 molecules. Then, under the mechanical action of the cerium oxide abrasive, the Si-O-Si bonds are broken, and the SiO2 molecular oxide layer is removed and polished by the cerium oxide abrasive, thereby achieving the polishing of the silicon carbide material. It can be seen from the above steps that the main rate-limiting steps for polishing the silicon carbide material using the ECMP method are the oxidation of the silicon carbide material surface and the polishing of the silicon dioxide molecular oxide layer by the cerium oxide abrasive.

[0095] Regarding the oxidizing agent, the composition is substantially free of oxidizing agents. In the prior art, hydrogen peroxide and sodium hypochlorite are generally used as oxidizing agents, but when the oxidizing agent is added to the composition, it will react with the cerium oxide abrasive particles, occupy the oxygen vacancies of the cerium oxide abrasive particles, thereby inhibiting the formation of the Ce-O-Si bond, and further reducing the material removal rate. Examples of unsuitable oxidizing agents include, but are not limited to, permanganic acid and its salts (such as potassium permanganate, sodium permanganate, etc.), persulfate compounds and their salts (such as persulfuric acid, peroxymonosulfuric acid, peroxydisulfuric acid, potassium persulfate, ammonium persulfate, etc.), peroxides (such as hydrogen peroxide, etc.), nitrate compounds and their salts and complexes (such as nitric acid, ferric nitrate, silver nitrate, aluminum nitrate, ceric ammonium nitrate), chlorine-containing compounds and their salts (chloric acid), perchloric acid and its salts (such as potassium perchlorate), bromine-containing compounds and their salts (such as bromic acid, potassium bromate ), iodine-containing compounds and their salts (such as iodic acid, ammonium iodate), periodic acid and its salts (such as sodium periodate, potassium periodate), ferric acid and its salts (such as ferric acid, potassium ferrate), chromic acid and its salts (such as chromic acid, potassium chromate, potassium dichromate), vanadic acid and its salts (such as vanadic acid, ammonium vanadate, sodium vanadate, potassium vanadate), ruthenic acid and its salts (such as perruthenic acid), molybdic acid and its salts (such as molybdic acid, ammonium molybdate, disodium molybdate), rhenic acid and its salts (such as perrhenic acid), tungstic acid and its salts (such as tungstic acid, disodium tungstate), combinations and derivatives thereof.

[0096] There are many factors that affect the oxidation rate of the silicon carbide material surface, such as electrolyte, etc. Among them, the electrolyte can enhance the conductivity of the composition, thereby enhancing the oxidation rate of the silicon carbide material surface, thereby improving the removal rate.

[0097] In the composition, there is no concentration gradient, and when electricity is applied, current can only be transmitted through ion migration. Adding an electrolyte to the composition increases the ion concentration, reduces the resistance of the composition, and thus improves the conductivity of the composition. Furthermore, the conductivity of the composition at a pH value of 3.0-4.5 is at least 0.07 mS / cm, for example, the conductivity of the composition at a pH value of 3.0-4.5 is 0.07 mS / cm, 0.1 mS / cm, 0.7 mS / cm, 0.5 mS / cm, 0.8 mS / cm, and 1 mS / cm. Furthermore, the conductivity of the composition at a pH value of 3.0-4.5 is at least 1 mS / cm, for example, the conductivity of the composition at a pH value of 3.0-4.5 is 1 mS / cm, 2 mS / cm, 3 mS / cm, 4 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 8 mS / cm, 9 mS / cm, or 10 mS / cm.

[0098] It should be noted that the above-mentioned pH value is only an exemplary display of the relationship between pH value and conductivity, and the relationship between pH value and conductivity in the present application is not limited to the above-mentioned case. The two can be any combination of the pH value range and the conductivity range mentioned in the present application. For example, the conductivity of the composition at a pH value of 2-7 is at least 1 mS / cm; the conductivity of the composition at a pH value of 3-6 is at least 1 mS / cm; the conductivity of the composition at a pH value of 3-4.5 is at least 1 mS / cm; the conductivity of the composition at a pH value of 4-5 is at least 1 mS / cm, and so on. No examples are listed here one by one.

[0099] The electrolyte in the composition may be an organic electrolyte. Further, the electrolyte may be an organic acid salt.

[0100] The metal ions may include alkali metal ions, alkaline earth metal ions and ammonium ions, wherein the alkali metal ions may include lithium (Li + ), sodium (Na + ), potassium (K + ), rubidium (Rb + ) and cesium (Cs + ), the alkaline earth metal ion can be beryllium (Be 2+ ), magnesium (Mg 2+ ), calcium (Ca 2+ ), Strontium (Sr 2+ ), barium (Ba 2+ ), radium (Ra 2+ ), ammonium ions can be NH4 + Furthermore, the metal ion is an alkali metal ion.

[0101] Studies have found that having more than one acid group can reduce the zeta potential of ceria abrasive particles or reverse the charge of ceria abrasive particles to a negative charge, significantly reducing material removal rates and leading to undesirable defects such as particle aggregation and scratches on the substrate surface. The organic acid has a maximum of three acid groups, more preferably a maximum of two acid groups, and even more preferably a single acid group. In some embodiments, the organic acid is a monoacid. In some embodiments, the ECMP composition does not contain an organic electrolyte having more than one acid group. For example, unsuitable organic electrolytes may be potassium citrate, sodium citrate, magnesium citrate, calcium citrate, potassium tartrate, sodium tartrate, magnesium tartrate, calcium tartrate, potassium malate, sodium malate, magnesium malate, calcium malate, potassium succinate, sodium succinate, magnesium succinate, calcium succinate, potassium adipate, sodium adipate, magnesium adipate, calcium adipate, potassium fumarate, sodium fumarate, magnesium fumarate, calcium fumarate, potassium oxalate, sodium oxalate, magnesium oxalate, calcium oxalate, potassium phthalate, sodium phthalate, magnesium phthalate, calcium phthalate, potassium glutarate, pentanoate ... Sodium disulfate, magnesium glutarate, calcium glutarate, potassium pyrolinolenate, sodium pyrolinolenate, magnesium pyrolinolenate, calcium pyrolinolenate, dihydrogen sulfates (e.g., potassium dihydrogen sulfate, sodium dihydrogen sulfate), pyrosulfates (e.g., potassium pyrosulfate), methane sulfonates (e.g., sodium methane sulfonate, potassium methane sulfonate), ethane phosphates (e.g., sodium ethane phosphate, potassium ethane phosphate), triphosphates (e.g., sodium triphosphate, potassium triphosphate), tetraphosphates (e.g., sodium tetraphosphate), diborates (e.g., sodium diborate), tetraborates (e.g., sodium tetraborate, commonly known as borax), or combinations thereof.

[0102] The organic acid providing the organic acid radical may be a monoacid, thereby forming an organic monoacid salt. The monoacid is an organic compound having one acid group. The monoacid may be in the form of an acid, a conjugate acid, a salt, or a combination thereof. Suitable acid groups include, for example, a carboxyl group, a sulfonic acid group, and a phosphonic acid group. Furthermore, the monoacid may be a monocarboxylic acid. The monocarboxylic acid may be a straight-chain monocarboxylic acid, a branched monocarboxylic acid, a saturated monocarboxylic acid, an unsaturated monocarboxylic acid, a substituted monocarboxylic acid, an aromatic monocarboxylic acid, and combinations thereof.

[0103] The monocarboxylic acid can be nicotinic acid, isonicotinic acid, quinonic acid, acetic acid, pyridinic acid, hydroxybenzoic acid, formic acid, carbonic acid, glycolic acid, glyoxylic acid, lactic acid, glyceric acid, pyruvic acid, oxypropionic acid, hydroxypropionic acid, oxypropionic acid, triglyceride, butyric acid, isobutyric acid, butyric acid, butyric acid, propionic acid, butyric acid, isooctanoic acid, isooctanoic acid, acrylic acid, methacrylic acid, vinylacetic acid, tetranitric acid, hydroxybutyric acid, oxybutyric acid, valeric acid, isovaleric acid, valeric acid, hexanoic acid, sorbic acid, benzoic acid, salicylic acid, octanoic acid, geranic acid, cinnamic acid, capric acid, myristic acid, palmitic acid, stearic acid, oxalic acid, propionic acid, propionic acid, hydroxypropionic acid, oxypropionic acid, At least one of dioxypropionic acid, vinylacetic acid, hydroxybutyric acid, β-hydroxybutyric acid, γ-hydroxybutyric acid, α-ketobutyric acid, succinic semialdehyde, methylbutyric acid, β-hydroxyvaleric acid, γ-hydroxyvaleric acid, β-hydroxyβ-methylbutyric acid, furanoic acid, tetrahydrofuranic acid, dimethylbutyric acid, dimethylbutyric acid, heptanoic acid, cyclohexanecarboxylic acid, dimethylvaleric acid, ethylvaleric acid, methylhexanoic acid, trimethylbutyric acid, ethylmethylbutyric acid, methylheptanoic acid, methylheptanoic acid, dimethylhexanoic acid, ethylhexanoic acid, octanoic acid, undecanoic acid, lauric acid, tricyclic acid, pentadecanoic acid, margarine acid, oleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid or stearic acid.

[0104] Furthermore, the organic acid radical in the organic salt can be a negative monovalent organic acid radical with a negative charge. For example, the organic acid providing the organic acid radical can be at least one of isonicotinic acid, glycolic acid, hydroxypropionic acid, butyric acid, isobutyric acid, butyric acid, propionic acid, acetic acid, valeric acid, sorbic acid, and propiolic acid, thereby forming at least one organic monoacid salt of isonicotinate, glycolic acid, hydroxypropionic acid, butyric acid, isobutyric acid, butyric acid, propionate, acetate, valeric acid, sorbic acid, or propiolic acid. The metal ion in the organic salt can be a positive monovalent metal ion with a positive charge. For example, the metal ion is sodium (Na + ) and / or potassium (K + The organic acid salt may be at least one of sodium isonicotinate, sodium glycolate, sodium hydroxypropionate, sodium butyrate, sodium isobutyrate, sodium butyrate, sodium propionate, sodium acetate, sodium valerate, sodium sorbate, sodium propiolate, potassium isonicotinate, potassium glycolate, potassium hydroxypropionate, potassium butyrate, potassium isobutyrate, potassium butyrate, potassium propionate, potassium acetate, potassium valerate, potassium sorbate or potassium propiolate.

[0105] When in use, an excessively high electrolyte concentration will cause the aggregation of the cerium oxide abrasive particles, reduce the removal rate of the cerium oxide abrasive particles, and shorten the shelf life of the cerium oxide abrasive particles. Therefore, it is necessary to select a suitable electrolyte concentration. Furthermore, when in use, the composition contains at least 0.0001wt% of an organic acid that provides the organic acid radical, such as when the composition contains 0.0001wt%, 0.001wt%, 0.007wt%, 0.013wt%, and 0.021wt% of an organic acid that provides the organic acid radical. When in use, the composition contains up to 9.7wt% of an organic acid that provides the organic acid radical, such as when the composition contains 9.7wt%, 4.4wt%, 2.3wt%, 1.2wt%, and 0.14wt% of an organic acid that provides the organic acid radical. In some embodiments, the composition comprises 0.0001 wt% to 9.7 wt%, 0.001 wt% to 4.4 wt%, 0.007 wt% to 2.3 wt%, or 0.013 wt% to 1.2 wt% of the organic acid providing the organic acid radical.

[0106] It should be noted that the above-mentioned organic acid salts are only exemplary displays. The organic acid salts do not only include the above-mentioned exemplary organic acid salts, but can also be any combination of the organic acid radicals and metal ions mentioned above. For example, the organic acid salts also include potassium oxybutyrate, sodium valerate, lithium isovalerate, lithium valerate, potassium hexanoate, sodium sorbate, sodium salicylate, barium octanoate, calcium geranium, potassium cinnamate, sodium caprate, lithium myristate, sodium palmitate, sodium stearate, calcium oxalate, barium propionate, potassium propionate, etc., which are not listed one by one here. In addition, the organic acid providing the organic acid radical in the electrolyte can be consistent with the organic acid in the pH regulator mentioned above, that is, the organic electrolyte and the pH regulator can be paired. For example, if the electrolyte is potassium isobutyrate, the pH regulator is isobutyric acid.

[0107] The composition is substantially free of inorganic electrolytes. In addition, the use of inappropriate electrolytes (e.g., inorganic electrolytes) will reduce or reverse the zeta potential of the cerium oxide abrasive, thereby causing the aggregation of the cerium oxide abrasive, shortening the shelf life of the composition and causing more defects. It should be noted that the electrolyte does not contain more than one acid group or carboxyl group, that is, the electrolyte cannot contain polyacids or polyhydroxy salts. The presence of polyacids or polyhydroxy salts will reduce the material removal rate. In addition, inorganic electrolytes will reduce the polishing effect of the composition, so the electrolyte does not include inorganic electrolytes. Among them, unsuitable inorganic electrolytes include chlorides (e.g., sodium chloride, potassium chloride, magnesium chloride, calcium chloride), hypochlorites (e.g., potassium hypochlorite, sodium hypochlorite, calcium hypochlorite), perchlorates (e.g., potassium perchlorate, sodium perchlorate, magnesium perchlorate), nitrates (e.g., potassium nitrate, sodium nitrate, magnesium nitrate, calcium nitrate), nitrites (e.g., sodium nitrite, potassium nitrite, magnesium nitrite), sulfates (e.g., sodium sulfate, potassium sulfate, magnesium sulfate (English name Epsom) salt), calcium sulfate (gypsum), phosphates (e.g. sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate), phosphates (e.g. sodium dihydrogen phosphate, potassium dihydrogen phosphate, magnesium dihydrogen phosphate), chlorates (e.g. potassium chlorate, sodium chlorate, magnesium chlorate), bromates (e.g. potassium bromate, sodium bromate, magnesium bromate, calcium bromate), iodates (e.g. sodium iodate, potassium iodate, calcium iodate), borates (e.g. sodium borate, potassium borate, magnesium borate, calcium borate), peroxide salts ( For example, potassium perbromate, sodium perbromate, potassium periodate, sodium periodate), carbonates (for example, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate), bicarbonates (for example, sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate), fluoride salts (for example, sodium fluoride, potassium fluoride, calcium fluoride), permanganates (for example, potassium permanganate, sodium permanganate), thiosulfates (for example, sodium thiosulfate, potassium thiosulfate), oxalates (for example, sodium oxalate, potassium oxalate, calcium oxalate), and combinations thereof.

[0108] In addition to the above factors, the removal rate enhancer also affects the polishing rate of the SiO2 molecular oxide layer by the cerium oxide abrasive particles. The removal rate enhancer can improve the material removal rate by interacting with the surface of the silicon carbide material.

[0109] Furthermore, the removal rate enhancer can be an amino acid. The amino acid can be a proteinogenic amino acid and / or a non-proteinogenic amino acid. Wherein, the proteinogenic amino acid can be at least one of alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, selenocysteine, and pyrrolysine. The non-proteinogenic amino acid can be at least one of ornithine, citrulline, carnitine, γ-aminobutyric acid, levothyroxine, β-alanine, or aminoisobutyric acid.

[0110] Furthermore, the amino acid is a proteinogenic amino acid. In some embodiments, the molecular weight of the amino acid is at most 150 g / mol, for example, 150 g / mol, 140 g / mol, 130 g / mol, 120 g / mol, etc.

[0111] When used, the composition comprises at least 0.002 wt% of amino acids, for example, the composition may comprise 0.002 wt%, 0.02 wt%, 0.12 wt%, 0.28 wt%, 0.46 wt% of amino acids. At the same time, the composition comprises up to 18.3 wt% of amino acids, for example, the composition may comprise 18.3 wt%, 9.8 wt%, 6.3 wt%, 4.3 wt%, 2.9 wt% of amino acids. In some embodiments, the composition comprises 0.002 wt% to 18.3 wt%, 0.02 wt% to 9.8 wt%, 0.12 wt% to 6.3 wt%, 0.28 wt% to 4.3 wt%, 4.3 wt% to 2.9 wt% of amino acids. In addition, the addition of amino acids of the right type and appropriate range can not only enhance the removal rate of the material, but also reduce the number of defects in the material during ECMP processing.

[0112] The composition may also include one or more biocides. The biocide may be a compound that prevents, inhibits, reduces the growth of, inhibits the activity of, or eliminates unwanted microorganisms. Examples of biocides are sodium hypochlorite, methylisothiazolinone, benzisothiazolinone, chloromethylisothiazolinone, and combinations thereof.

[0113] The composition comprises at least 0.6 ppm by weight of the biocide, for example, the composition comprises 0.6 ppm, 1.6 ppm, 2.7 ppm, 3.8 ppm, or 4.6 ppm by weight. High concentrations of the biocide can lead to undesirable interactions between the biocide and other components and materials of the composition. Thus, the composition comprises up to 98 ppm by weight, for example, the composition comprises 98 ppm, 83 ppm, 74 ppm, or 69 ppm by weight of the biocide.

[0114] It should be noted that, in some embodiments, the composition may not contain a biocide, and in this case, the composition may still exhibit a favorable high material removal rate.

[0115] The present invention also relates to uses of the electrochemical mechanical polishing composition. The electrochemical mechanical polishing composition of the present invention is used for electrochemical mechanical polishing of materials comprising silicon. As known to those skilled in the art, electrochemical mechanical polishing refers to a process in which a material is placed in an ECMP apparatus and a current is applied, causing the material to contact a polishing pad and the electrochemical mechanical polishing composition positioned therebetween. The polishing pad and the material are moved relative to each other to remove portions of the material. Examples of silicon materials include silicon carbide, crystalline silicon, silicon oxide, tetraethyl orthosilicate (TEOS), silicon nitride, and combinations thereof.

[0116] In some embodiments, the electrochemical mechanical polishing composition of the present invention is used for electrochemical mechanical polishing of materials containing silicon carbide.

[0117] In addition to the above electrochemical mechanical polishing composition and its uses, the present invention also provides a method for electrochemical mechanical polishing of silicon carbide materials, wherein the polishing liquid used in the method is the above electrochemical mechanical polishing composition.

[0118] The steps of electrochemical mechanical polishing of silicon carbide material are as follows:

[0119] S1, preparing an electrochemical mechanical polishing composition and placing it on a polishing pad in a polishing machine.

[0120] S2, placing a working electrode and a counter electrode in the above-mentioned electrochemical mechanical polishing composition so that the working electrode and the counter electrode are in contact with the electrochemical mechanical polishing composition, and applying a current between the working electrode and the counter electrode to perform an electrochemical oxidation reaction on the surface of the silicon carbide material to form a SiO2 oxide layer, wherein the working electrode is the silicon carbide material bonded to the lower surface of the polishing head.

[0121] S3, dispersing the cerium oxide abrasive particles in the electrochemical mechanical polishing composition, bringing the silicon carbide material into contact with the polishing pad, and moving the polishing head and the polishing pad to polish the SiO2 oxide layer.

[0122] The cerium oxide abrasive particles can be prepared by any suitable method known to those skilled in the art to impart the above-mentioned properties to the abrasive particles. In an embodiment, the cerium oxide abrasive particles can be prepared by precipitation of cerium nitrate in an alkaline solution and by preparing abrasive particles of suitable size and morphology under suitable conditions. The abrasive particles can be centrifuged, washed and dried. The particles can be deagglomerated by further processing such as filtering, grading, crushing, grinding, milling, ultrasonic treatment and combinations thereof. The particles are dispersed and used to formulate a composition. Useful dispersion processes can be, for example, high shear mixing, ultrasonic treatment and other processes known to those skilled in the art.

[0123] The composition can be prepared using suitable techniques known to those skilled in the art. The cerium oxide abrasive particles as described above and other components other than the cerium oxide abrasive particles can be added to the aqueous carrier in any order and in suitable amounts to achieve the desired concentration. The cerium oxide abrasive particles and other components can be mixed and stirred in the aqueous carrier. The pH value can be adjusted using the above-mentioned pH regulators and pH buffers to obtain and maintain the desired pH. The cerium oxide abrasive particles and other components can be added at any time before use (e.g., one month, one day, one hour, or one minute) or during the ECMP treatment process.

[0124] The composition can be provided as a one-part system, a two-part system, or a multi-part system. For example, as a two-part system, the first part can include the cerium oxide abrasive particles and the second part can include one or more other components. The first and second parts can be mixed at any time before ECMP treatment (e.g., one month, one day, one hour, or one minute) or during ECMP treatment.

[0125] The composition can be provided as a concentrate and can be diluted with an appropriate amount of water before use. The concentration of the components in the composition can be any suitable concentration, for example 2 times, 3 times, 10 times or 25 times the above-mentioned concentration when used. For example, the concentration of the cerium oxide abrasive and other components contained in the concentrate is such that after dilution with an appropriate amount of water, the cerium oxide abrasive and other components are present in the composition at the above-mentioned concentrations. If the composition is provided, for example, as a two-part system, one or both parts can be provided as a concentrate. The two parts can be provided at different concentrations, for example the first part can be provided at a concentration of three times and the second part at a concentration of five times. The two parts can be diluted in any order before mixing.

[0126] During polishing, the electrode contacts the composition and provides an electronic conductor for the composition to realize the input or output of electrical energy, and the silicon carbide material serves as the working electrode and is the place where the electrochemical reaction occurs. The platinum electrode serves as the counter electrode and forms a loop with the working electrode to make the current on the working electrode flow smoothly to ensure that the reaction under study occurs on the working electrode. In addition to the platinum electrode, the counter electrode can also be a graphite rod electrode. The saturated calomel electrode serves as the reference electrode, and its potential is not affected by changes in the composition of the composition and has a constant value. In addition to the saturated calomel electrode, the reference electrode can also be an Ag / AgCl electrode, a mercury oxide electrode, and a mercurous sulfate electrode.

[0127] The composition acts as a carrier for ion transport in the electrolytic cell, conducting ions between the electrodes. When energized, the composition undergoes ion migration under the action of the current, thereby oxidizing the silicon carbide material. This can oxidize Si-C bonds on the surface of the silicon carbide material into Si-O bonds, forming a SiO2 oxide layer. This reduces the Mohs hardness of the silicon carbide surface and achieves efficient oxidation of the silicon carbide surface.

[0128] In the step, the cerium oxide abrasive can form Ce-O-Si bonds with the SiO2 molecules and weaken the Si-O-Si bonds between the SiO2 molecules, so that the Si-O-Si bonds are broken under the action of the cerium oxide abrasive. The cerium oxide abrasive removes and polishes the SiO2 molecular oxide layer in a whole block to achieve polishing of the silicon carbide material.

[0129] The following are specific examples of compositions designed based on the above disclosure. It should be understood that the following examples are merely illustrative of the compositions and polishing methods disclosed above, and that the specific embodiments and parameters used herein represent only one or more of the numerous parameters and methods described above. Those skilled in the art can, based on the disclosure herein, use other parameters and perform electrochemical mechanical polishing according to the above method without departing from the core principles disclosed herein.

[0130] In the following examples, the method for synthesizing cubic cerium dioxide abrasive particles of the present invention is as follows: 0.03 mol of cerium (III) nitrate (Ce(NO3)3·6H2O) is dissolved in 100 mL of deionized water and stirred at room temperature until the solid is dissolved, which is recorded as liquid A. 3.6 mol of sodium hydroxide (NaOH) is dissolved in 500 mL of deionized water, stirred until the solid is dissolved, and cooled to room temperature, which is recorded as liquid B. While stirring at room temperature, liquid A is slowly added to liquid B, and stirring is continued for 30 minutes. The mixture is transferred to a stainless steel hydrothermal autoclave with a Teflon liner, the synthesis temperature is 120°C, the reaction time is 24 hours, and then it is naturally cooled to room temperature. The cooled mixture is centrifuged to obtain a white solid. The white solid obtained by centrifugation is washed three times with water and ethanol respectively until the conductivity of the supernatant is less than 1 mS / cm. The solid obtained from the final wash is dried at 120°C to obtain cerium dioxide abrasive particles with a cubic morphology.

[0131] In the following examples, the preparation method of the uncalcined truncated octahedral cerium oxide used in the examples of the present invention is as follows: 200g of cerium nitrate Ce(NO3)36H2O is dissolved in 500mL of deionized water, and stirred at room temperature until the solid is dissolved, which is recorded as solution A. 100ml of ammonia water is dissolved in 400ml of deionized water, and stirred until the solid is dissolved, which is recorded as solution B. Stirring at room temperature, solution B is slowly added to solution A, and stirring is continued for 30min. The mixed solution is placed in a water bath, the synthesis temperature is 85°C, and the reaction time is 4 hours. The cooled mixture is centrifuged to obtain a white solid, and water and acetic acid are added to acidify it to obtain a suspension of truncated octahedral cerium oxide.

[0132] In the following examples, the preparation method of the calcined truncated octahedral cerium oxide used in the examples of the present invention is as follows: the white solid obtained from the above-mentioned uncalcined truncated octahedral cerium oxide is placed in a high-temperature muffle furnace and calcined at 750 degrees Celsius for 2 hours to obtain a yellow solid powder, which is then ground and re-dispersed and homogenized using high shear to obtain a suspension of calcined truncated octahedral cerium oxide.

[0133] In the following examples, a 100 mm N-type (0.01-0.03 Ωcm) 4H-SiC wafer was used. The Si surface of the SiC wafer was polished using a UNIPOL-1200S polisher (Shenyang Jingke Co., Ltd.). A platinum electrode served as the counter electrode, the SiC wafer served as the working electrode, and a saturated calomel electrode served as the reference electrode. The polishing head speed was 60 rpm, the polishing pad speed was 63 rpm, and the polishing pressure was 5 psi. ECMP estimated the SiC material removal rate by measuring weight loss during polishing.

[0134] Example 1

[0135] The electrochemical mechanical polishing composition comprises 2 wt.% ceria, 0.02 wt.% MOPS (4-morpholinepropanesulfonic acid (MOPS), 0.05 wt.% glutamic acid, 0.1 M electrolyte (as shown in Table 1), 0.5 wt.% PPG (MW 600 g / mol), and 0.2 wt.% PEG (MW 1000 g / mol). The pH is adjusted to 4 with potassium hydroxide. The ceria is selected from cubic ceria, uncalcined truncated octahedral ceria, calcined truncated octahedral ceria, and uncalcined truncated octahedral ceria (purchased). Table 1a lists the silicon carbide material removal rates corresponding to the addition of different electrolytes to the electrochemical mechanical polishing composition when the ceria is cubic ceria.

[0136] Table 1a

[0137] As can be seen from Table 1a, compared to electrochemical mechanical polishing composition A1a, electrochemical mechanical polishing compositions A2a to A14a, which contain an electrolyte, exhibited improved silicon carbide material removal rates. This indicates that the addition of an electrolyte to the electrochemical mechanical polishing composition can increase the silicon carbide material removal rate. Furthermore, compared to electrochemical mechanical polishing compositions A2a to A4a, electrochemical mechanical polishing compositions A5a to A14a exhibited improved silicon carbide material removal rates. This indicates that the addition of an organic electrolyte to the electrochemical mechanical polishing composition can increase the silicon carbide material removal rate.

[0138] Table 1b lists the silicon carbide material removal rates corresponding to the electrochemical mechanical polishing composition in which the ceria is uncalcined truncated octahedral ceria and different electrolytes are added.

[0139] Table 1b

[0140] As can be seen from Table 1b, compared to electrochemical mechanical polishing composition A1b, electrochemical mechanical polishing compositions A2b to A14b, which contain electrolytes, exhibit higher silicon carbide material removal rates. This indicates that the addition of electrolytes to the electrochemical mechanical polishing compositions can increase silicon carbide material removal rates. Furthermore, compared to electrochemical mechanical polishing compositions A2b to A4b, electrochemical mechanical polishing compositions A5b to A14b exhibit even better silicon carbide material removal rates. This indicates that the addition of organic electrolytes to the electrochemical mechanical polishing compositions can increase silicon carbide material removal rates. Furthermore, while the electrochemical mechanical polishing compositions containing uncalcined chamfered octahedral ceria exhibited higher silicon carbide material removal rates, the electrochemical mechanical polishing compositions containing uncalcined chamfered octahedral ceria exhibited lower silicon carbide material removal rates than the cubic ceria in Table 1a.

[0141] Table 1c lists the silicon carbide material removal rates corresponding to the electrochemical mechanical polishing composition in which the ceria is calcined truncated octahedral ceria and different electrolytes are added.

[0142] Table 1c

[0143] As can be seen from Table 1c, compared to electrochemical mechanical polishing composition A1c, electrochemical mechanical polishing compositions A2c to A14c, which contain electrolytes, exhibit higher silicon carbide material removal rates. This indicates that the addition of electrolytes to the electrochemical mechanical polishing compositions can increase silicon carbide material removal rates. Furthermore, compared to electrochemical mechanical polishing compositions A2c to A4c, electrochemical mechanical polishing compositions A5c to A14c exhibit even better silicon carbide material removal rates. This indicates that the addition of organic electrolytes to the electrochemical mechanical polishing compositions can increase silicon carbide material removal rates. Furthermore, compared to the uncalcined truncated octahedral cerium oxide in Table 1b, the electrochemical mechanical polishing compositions containing calcined truncated octahedral cerium oxide exhibit even higher silicon carbide material removal rates.

[0144] Table 1d lists the silicon carbide material removal rates when the ceria is uncalcined truncated octahedral ceria (purchased) and different electrolytes are added to the electrochemical mechanical polishing composition.

[0145] Table 1d

[0146] As can be seen from Table 1d, the electrochemical mechanical polishing composition to which uncalcined chamfered octahedral ceria (commercially available) was added had a lower silicon carbide material removal rate than the uncalcined chamfered octahedral ceria and the calcined chamfered octahedral ceria in Tables 1b and 1c.

[0147] Example 2

[0148] The electrochemical mechanical polishing composition consists of 1 wt.% cubic ceria, 0.1 M potassium isobutyrate, 0.04 wt.% picolinic acid, 0.03 wt.% glycine, and 0.8 wt.% polyethylene glycol (Mw 600), with the pH adjusted to 3.5 with isobutyric acid. The cubic ceria has different particle size distributions as listed in Table 2. The cubic ceria of Examples B1-B4 were synthesized according to the above method, with slight adjustments to the raw material ratios, temperature, and reaction time to obtain cubic ceria with different particle size distributions. The different particle size distributions listed in Table 2 were achieved. The scratch coefficient was evaluated by counting the number of scratches and calculating the sum of the lengths of all detected scratches. If the total scratch length is less than 20% of the SiC wafer diameter, the score is A; if the total scratch length is 20%-40% of the SiC wafer diameter, the score is B; if the total scratch length is 40%-75% of the SiC wafer diameter, the score is C; if the total scratch length is more than 75% of the SiC wafer diameter, the score is D. Table 2 lists the SiC removal rates corresponding to different ceria.

[0149] As described above, particle sizes D01, D30, D50, D70, D99 and z-average particle size were obtained by laser diffraction using a Horiba LA-960. The zeta potential of the compositions was measured using a Nano ZSE (Malvern Instruments).

[0150] Table 2

[0151] As can be seen from Table 2, compared to EMP compositions B1 and B4, EMP compositions B2 and B3 have lower average particle sizes, higher steepness factors, and lower slope factors, and exhibit higher material removal rates and lower scratch coefficients. Therefore, a low slope factor, high steepness factor, and low average particle size result in fewer scratches and enhanced silicon carbide material removal rates.

[0152] Example 3

[0153] The electrochemical mechanical polishing composition comprises 1.5 wt.% ceria, 0.05 wt.% MOPS, 0.06 wt.% proline, 0.1 M potassium propionate, 1 wt.% PEG (Mw800), and 0.1 wt.%, wherein the pH of the electrochemical mechanical polishing composition is adjusted to 3.5 with propionic acid. Table 3 lists the ceria, wherein the ceria is cubic ceria, uncalcined truncated octahedral ceria, calcined truncated octahedral ceria, and uncalcined truncated octahedral ceria (purchased).

[0154] Table 3a lists the silicon carbide material removal rates when the ceria is cubic ceria and an oxidizing agent is added to the electrochemical mechanical polishing composition.

[0155] Table 3a

[0156] As can be seen from Table 3a, the removal rates of silicon carbide materials for electrochemical mechanical polishing compositions C2a to C8a, which contain an oxidizing agent, are lower than those for electrochemical mechanical polishing composition C1a. Therefore, the addition of an oxidizing agent to the electrochemical mechanical polishing composition reduces the removal rate of silicon carbide materials.

[0157] Table 3b lists the silicon carbide material removal rates for uncalcined truncated octahedral ceria and for the addition of an oxidizing agent to the electrochemical mechanical polishing composition.

[0158] Table 3b

[0159] As can be seen from Table 3b, compared with the electrochemical mechanical polishing composition C1b, the electrochemical mechanical polishing compositions C2b to C8b with the addition of an oxidizing agent have lower removal rates of silicon carbide materials. Therefore, the addition of an oxidizing agent to the electrochemical mechanical polishing composition reduces the removal rate of silicon carbide materials.

[0160] Although the electrochemical mechanical polishing compositions with the addition of uncalcined chamfered octahedral ceria exhibited higher silicon carbide material removal rates, the electrochemical mechanical polishing compositions with the addition of uncalcined chamfered octahedral ceria exhibited lower silicon carbide material removal rates compared to the cubic ceria in Table 3a.

[0161] Table 3c lists the silicon carbide material removal rates when the ceria is calcined truncated octahedral ceria and an oxidizing agent is added to the electrochemical mechanical polishing composition.

[0162] Table 3c

[0163] As can be seen from Table 3c, compared with the electrochemical mechanical polishing composition C1c, the electrochemical mechanical polishing compositions C2c to C8c with the addition of an oxidizing agent have lower silicon carbide removal rates. Therefore, the addition of an oxidizing agent to the electrochemical mechanical polishing composition reduces the silicon carbide removal rate.

[0164] The electrochemical mechanical polishing compositions to which the calcined chamfered octahedral ceria was added exhibited higher silicon carbide material removal rates compared to the uncalcined chamfered octahedral ceria in Table 3b.

[0165] Table 3d lists the silicon carbide material removal rates when the ceria is uncalcined truncated octahedral ceria (purchased) and an oxidizing agent is added to the electrochemical mechanical polishing composition.

[0166] Table 3d

[0167] As can be seen from Table 3d, the electrochemical mechanical polishing composition to which uncalcined chamfered octahedral ceria (commercially available) was added had a lower silicon carbide material removal rate than the uncalcined chamfered octahedral ceria and the calcined chamfered octahedral ceria in Tables 3b and 3c.

[0168] Example 4

[0169] The flat particle size of the particles of uncalcined truncated octahedral cerium oxide (purchased), uncalcined truncated octahedral cerium oxide (prepared according to the present invention), and calcined truncated octahedral cerium oxide (prepared according to the present invention) in Tables 1b, 1c, 1d, 3b, 3c, and 3d above was evaluated using a NovaNano 450 scanning electron microscope. The average particle size was obtained by the arithmetic mean of the maximum distance between two points on the particle boundary measured from 1000 particles. As described above, the coefficient of variation (CV) of the average particle size was obtained by the formula CV = (σ / μ) × 100% (σ is the standard deviation of the average particle size, and μ is the average particle size). The polydispersity index (PDI) was obtained by the formula PDI = σ 2 / μ 2 The values ​​were obtained and listed in Table 2. To obtain the ratio of (cumulative volume of particles exceeding 2 times the average particle size) / (cumulative volume of particles having the largest average particle size) in Table 2, the volume of the truncated octahedral cerium oxide particles was calculated using the general mathematical formula for square particles and spheres (using the assumption of spherical particles).

[0170] Table 4

[0171] As can be seen in Table 4, the CV of the uncalcined and calcined truncated octahedral ceria (prepared according to the present invention) is higher than that of the uncalcined truncated octahedral ceria (purchased), indicating that the uncalcined and calcined truncated octahedral ceria (prepared according to the present invention) have a wider particle size distribution. The PDI of the uncalcined and calcined truncated octahedral ceria (prepared according to the present invention) is higher than that of the uncalcined truncated octahedral ceria (purchased), exceeding 0.1, indicating that the uncalcined and calcined truncated octahedral ceria (prepared according to the present invention) have a polydisperse distribution, while the uncalcined truncated octahedral ceria (prepared according to the present invention) has a monodisperse distribution. The fraction of particles exceeding twice the average particle size of the uncalcined and calcined truncated octahedral ceria (prepared according to the present invention) is significantly higher than that of the uncalcined truncated octahedral ceria (purchased). Compared with uncalcined truncated octahedral cerium oxide (purchased), the cumulative volume of particles exceeding 2 times the average particle size (cumulative volume of particles with the largest average particle size) of uncalcined and calcined truncated octahedral cerium oxide (prepared according to the present invention) is significantly higher, indicating that the large particles in the uncalcined and calcined truncated octahedral cerium oxide (prepared according to the present invention) account for a large proportion of the total particle volume.

[0172] Example 5

[0173] Raman spectra were measured using the cubic ceria described in Tables 1a and 3a above: The cubic ceria particles were centrifuged, the supernatant removed, and the particles dried at 60°C overnight. Raman spectroscopy was applied to the dried powder using a Horiba iHR550 spectrometer (Horiba) at 25°C using a 532 nm laser. The spectra were baseline corrected using iterative reweighted least squares and normalized to the intensity of the F2g peak. The FWHM (full width at half maximum) calculated as described above was 9.724, the FWTM (full width at 1 / 3 maximum peak) was 14.045, the D50 was 81.63, the ratio of D50 to FWHM was 8.39, and the ratio of D50 to FWTM was 5.81.

[0174] Finally, it should be understood that the embodiments of the application disclosed herein are illustrative of the principles of the embodiments of this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can adopt alternative configurations based on the embodiments in this specification to implement the application in this specification. Therefore, the embodiments of this specification are not limited to the embodiments precisely described in the application.

Claims

1. An electrochemically mechanical polishing composition for electrochemically mechanically polishing a silicon carbide substrate, characterized in that, Comprising: A liquid carrier; A pH regulator; An organic electrolyte; And Truncated octahedral cerium oxide abrasive grains, dispersed in the liquid carrier, wherein the ratio of the cumulative volume of abrasive grains in the truncated octahedral cerium oxide abrasive grains having a size more than twice the average particle size measured by scanning electron microscope to the cumulative volume of abrasive grains in the truncated octahedral cerium oxide abrasive grains having a size less than or equal to the average particle size measured by scanning electron microscope is at least 0.

1.

2. The electrochemical mechanical polishing composition according to claim 1, wherein The pH value of the electrochemical mechanical polishing composition is 2 - 7.

3. The electrochemical mechanical polishing composition according to any one of claims 1-2, characterized in that The truncated octahedral cerium oxide abrasive grains have a zeta potential of at least 10 mV at a pH value of 3.5 - 4.5 of the electrochemical mechanical polishing composition.

4. The electrochemical mechanical polishing composition according to any one of claims 1-3, characterized in that The conductivity of the electrochemical mechanical polishing composition at a pH value of 3.5 - 4.5 is at least 1 mS / cm.

5. The electrochemically-mechanical polishing composition according to any one of claims 1-4, characterized in that, The pH regulator comprises an organic acid.

6. The electrochemically-mechanical polishing composition according to any one of claims 1-5, characterized in that, The organic electrolyte comprises an organic mono - salt.

7. The electrochemically-mechanical polishing composition according to claim 6, wherein The organic mono - salt is at least one of isonicotinate, glycolate, hydroxypropionate, butyrate, isobutyrate, valerate, propionate, acetate, pentanoate, sorbate, propiolate.

8. The electrochemical mechanical polishing composition according to any one of claims 1-5, characterized in that, The coefficient of variation of the average particle size of the truncated octahedral cerium oxide abrasive grains measured by scanning electron microscope is greater than 30%.

9. The electrochemically-mechanical polishing composition according to any one of claims 1-8, characterized in that, The truncated octahedral cerium oxide abrasive grains have a non - monodisperse particle size distribution, which is measured by scanning electron microscope.

10. The electrochemically-mechanical polishing composition according to any one of claims 1-9, characterized in that, The polydispersity index of the truncated octahedral cerium oxide abrasive grains measured by scanning electron microscope is at least 0.

1.

11. The electrochemically-mechanical polishing composition according to any one of claims 1-10, characterized in that, At least 0.5% of the abrasive grains in the truncated octahedral cerium oxide abrasive grains have a size greater than twice the average particle size measured by scanning electron microscope.

12. The electrochemically-mechanical polishing composition according to any one of claims 1-11, characterized in that, The average particle size of the truncated octahedral cerium oxide abrasive grains measured by scanning electron microscope is 20 nm - 100 nm.

13. The electrochemical mechanical polishing composition according to any one of claims 1 - 12, wherein the truncated octahedral cerium oxide abrasive grains comprise calcined truncated octahedral cerium oxide sol.

14. Use of an electrochemically-mechanical polishing composition, characterized in that, Using the electrochemical mechanical polishing composition according to any one of claims 1 to 13 for the electrochemical mechanical polishing of a silicon carbide material.

15. A method for electrochemically mechanical polishing of silicon carbide materials, characterized in that, Comprising the following steps: (1) Prepare the electrochemical mechanical polishing composition according to any one of claims 1 to 13 and place it on a polishing pad; (2) Place a working electrode and a counter electrode in the electrochemical mechanical polishing composition so that the working electrode and the counter electrode are in contact with the electrochemical mechanical polishing composition, and apply a current between the working electrode and the counter electrode to carry out an electrochemical oxidation reaction on the surface of the silicon carbide material to form a silicon oxide layer, wherein the working electrode is the silicon carbide material bonded to the lower surface of the polishing head; (3) The truncated octahedral cerium oxide abrasive grains are dispersed in the electrochemical mechanical polishing composition, bring the silicon carbide material into contact with the polishing pad, and move the polishing head and the polishing pad to polish the silicon oxide layer.

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