Electrochemical mechanical polishing composition, application and method

Abstract

The invention provides an electrochemical mechanical polishing composition, application and a method, and relates to the technical field of polishing processing. The electrochemical mechanical polishing composition comprises a liquid carrier, a pH regulator, an organic electrolyte and CeO2 abrasive particles, the CeO2 abrasive particles are dispersed in the liquid carrier, after electrification, the surface of the SiC material is oxidized to form a SiO2 molecule oxide layer, the CeO2 abrasive particles can form Ce-O-Si bonds with SiO2 molecules and weaken Si-O-Si bonds among the SiO2 molecules, and the SiO2 molecules are oxidized to form a SiO2 molecule oxide layer. Therefore, the Si-O-Si bond is broken under the action of the CeO2 abrasive particles, and the CeO2 abrasive particles are used for removing and polishing the SiO2 molecular oxide layer, so that the polishing of the SiC material is realized. The electrochemical mechanical polishing composition can realize high-efficiency and high-quality polishing.

Description

Technical Field

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

[0002] As a third-generation semiconductor material, SiC has broad application scenarios in fields such as aerospace, new energy vehicles, and consumer electronics. However, due to the high hardness and high stability of SiC materials, the polishing is difficult, resulting in low polishing efficiency and extremely low material removal rate of SiC materials.

[0003] Currently, the main polishing method for SiC materials is Chemical Mechanical Polishing (CMP for short). CMP is a process technology that organically combines the physical grinding action of nano-scale particles with the chemical corrosion action of the polishing liquid to smooth the surface of SiC materials and make it highly flat. The current main rate-limiting step in using the CMP polishing method is the oxidation of the SiC surface. In order to obtain a high material removal rate, a new polishing method and polishing composition are needed to increase the oxidation rate of the SiC surface. Summary of the Invention

[0004] Based on the above problems, the present application provides an electrochemical mechanical polishing composition, uses, and methods, using CeO2 abrasive particles for electrochemical mechanical polishing of SiC materials to increase the oxidation rate and mechanical polishing rate of SiC materials, and thus achieve high-efficiency and high-quality polishing of SiC materials.

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

[0006] In a first aspect, the present application provides an electrochemical mechanical polishing composition including a liquid carrier, a pH regulator, an organic electrolyte, and CeO2 abrasive particles. The CeO2 abrasive particles are dispersed in the liquid carrier. After being energized, an SiO2 molecular oxide layer is formed on the surface of the SiC material. The CeO2 abrasive particles can form Ce-O-Si bonds with the SiO2 molecules and weaken the Si-O-Si bonds between the SiO2 molecules. Therefore, under the action of the CeO2 abrasive particles, the Si-O-Si bonds are broken, and the CeO2 abrasive particles remove and polish the SiO2 molecular oxide layer to achieve polishing of the SiC material. The electrochemical mechanical polishing composition can achieve high-efficiency and high-quality polishing.

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

[0008] In some embodiments, the CeO2 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.

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

[0010] In some embodiments, the pH regulator includes 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, valerate, propionate, acetate, pentanoate, sorbate, propiolate.

[0013] In some embodiments, the average particle size of the CeO2 abrasive grains does not exceed 95 nm.

[0014] In some embodiments, the composition does not contain inorganic acid.

[0015] In a second aspect, the present application provides a use of an electrochemical mechanical polishing composition, using the electrochemical mechanical polishing composition according to any one of claims 1 to 9 for the electrochemical mechanical polishing of SiC materials.

[0016] In a third aspect, the present application provides a method for electrochemically mechanically polishing SiC materials, comprising the following steps:

[0017] (1) Prepare the electrochemical mechanical polishing composition according to any one of claims 1 to 9 and place it on a polishing pad;

[0018] (2) Place the working electrode and the 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 SiC material to form a SiO2 oxide layer, wherein the working electrode is the SiC material bonded to the lower surface of the polishing head;

[0019] (3) Disperse the CeO2 abrasive grains in the electrochemical mechanical polishing composition, bring the SiC material into contact with the polishing pad, and move the polishing head and the polishing pad to polish the SiO2 oxide layer.

[0020] Through the above technical solutions, by using the electrochemical mechanical polishing method to polish the SiC material, the oxidation rate and the mechanical polishing rate of the SiC material surface are improved, and the surface and subsurface damage of the SiC material are reduced, so as to achieve high-efficiency and high-quality polishing. Specific embodiments

[0021] The following description provides specific application scenarios and requirements of this specification, aiming to enable those skilled in the art to manufacture and use the content in this specification. For those skilled in the art, various local modifications to the disclosed embodiments are obvious, and without departing from the spirit and scope of this specification, the general principles defined here can be applied to other embodiments and applications. Therefore, this specification is not limited to the illustrated embodiments, but has the broadest scope consistent with the claims.

[0022] The terms used herein are for the purpose of describing specific example embodiments only and are not restrictive. For example, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" used herein may also include the plural forms. When used in this specification, the terms "comprises", "comprising", and / or "containing" mean that the associated integers, steps, operations, elements, and / or components exist, but do not exclude the existence 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.

[0023] The term "substantially free of component X" as used herein means that the composition substantially does not contain the component X, that is, the component can at most exist as an impurity or contaminant in the composition, but is not added to the composition as a single component. This means that the component X is not added in a substantial amount.

[0024] In this application, "X includes at least one of A, B, or C" (X includes at least one of A, B, or C) means that X includes at least A (X includes at least A), or X includes at least B (X includes at least B), or X includes at least C (X includes at least C). That is to say, X can only include any combination of A, B, C, or can include any combination of A, B, C and other possible contents / elements at the same time. Any combination of A, B, C can be A, B, C, AB, AC, BC, or ABC.

[0025] As a most representative third-generation semiconductor material, SiC materials are widely used in many important fields such as IT, consumer, automotive, industrial, aerospace, smart grid, rail transit, power electronics, and ships.

[0026] Currently, the processing technological process of SiC materials is roughly as follows: cutting, rough grinding, fine grinding, rough polishing (mechanical polishing), fine polishing (chemical mechanical polishing), etc. In fine polishing, the chemical mechanical polishing (CMP for short) method is usually used. CMP is a process technology that organically combines the physical grinding effect of nano-level particles with the chemical corrosion effect of the polishing liquid to smooth the surface of SiC materials and make it highly flat. The main rate-limiting step of the CMP polishing method is the oxidation of the SiC material surface. In the prior art, strong oxidants such as potassium permanganate and hydrogen peroxide are usually used to oxidize the SiC surface to improve the oxidation rate of the SiC material surface. However, these strong oxidants have problems such as environmental pollution, contamination of the polishing pad, and low oxidation efficiency during use.

[0027] In addition, mechanically polishing the SiC surface oxide layer with alumina abrasive grains or diamond abrasive grains in the prior art will cause surface and subsurface damage, directly affecting the quality of SiC materials.

[0028] In view of this, this application adopts the electro-chemical mechanical polishing (ECMP for short) method to provide an electro-chemical mechanical polishing composition, use, and method, which can improve the polishing quality while increasing the oxidation rate of the SiC material surface, thereby achieving high-efficiency and high-quality polishing.

[0029] The composition is used for polishing SiC materials. Depending on the different close-packed arrangements of carbon and silicon atoms, the SiC can form different crystal structures, such as the cubic close-packed crystal structure represented by 3C-SiC, the hexagonal close-packed crystal structures represented by 2H-SiC, 4H-SiC, and 6H-SiC, and the rhombohedral close-packed crystal structure represented by 15R-SiC, etc. The composition can be used to polish SiC materials with any crystal structure, and no limitation is made here.

[0030] The composition includes a liquid carrier, a pH regulator, an organic electrolyte, and abrasive grains. Among them, the pH regulator is used to adjust the pH value of the composition so that the composition can achieve the best effect during the polishing process. The organic electrolyte provides conductive ions to enhance the conductivity of the composition. The abrasive grains are used for the polishing of SiC materials. The liquid carrier serves as the base of the composition and can accommodate various components, such as a pH regulator, an organic electrolyte, and abrasive grains. The composition may also include chemical additives to enhance the interaction between the abrasive grains and the SiC material. In addition, the composition may also include a biocide to inhibit or eliminate unwanted microorganisms in the composition.

[0031] The composition further includes one or more chemical additives. The chemical additives can interact with, for example, the CeO2 abrasive grains and / or with the SiC material and / or with 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 any component suitable for use as, for example, a removal rate promoter, a polishing rate inhibitor, a surfactant, a thickener, a regulator, a complexing agent, a chelating agent, a biocide, a dispersant, an oxidant, a film-forming agent, an etching inhibitor, a catalyst, a termination compound, a dissolution inhibitor, a corrosion inhibitor, or a combination thereof. Among them, electrolytes, pH regulators, polymers, amino acids, etc. can all be considered chemical additives.

[0032] The liquid carrier can accommodate other components in the composition except the liquid carrier itself, such as the abrasive grains, the pH regulator, the organic electrolyte, etc., to suspend these components in the liquid carrier and contact the material for polishing. The liquid carrier can be an aqueous carrier, and the liquid carrier can be any component suitable for suspending abrasive grains and chemical additives. For example, it can be one of water, ethers (such as dioxane and tetrahydrofuran), alcohols (such as methanol and ethanol), or a combination of water, ethers (such as dioxane and tetrahydrofuran), and alcohols (such as methanol and ethanol). When the liquid carrier is a combination of multiple components, the liquid carrier contains at least 50 wt% (weight) of water. For example, the aqueous carrier contains 50 wt% (weight) of water, 70 wt% (weight) of water, 90 wt% (weight) of water, 95 wt% (weight) of water, 99 wt% (weight) of water. Further, the water is deionized water.

[0033] Abrasive grains, as the main substances for mechanical polishing, are dispersed in the above-mentioned liquid carrier. The abrasive grains may be at least one metal oxide abrasive grain among cerium oxide (cerium dioxide), aluminum oxide (aluminum oxide), silicon oxide (silicon dioxide), zirconium oxide (zirconium oxide), titanium oxide (titanium dioxide), germanium oxide (germanium oxide), magnesium oxide (magnesium oxide), nickel oxide, gallium oxide (gallium oxide), yttrium oxide (yttrium oxide).

[0034] Furthermore, the abrasive grains may be cerium oxide abrasive grains. Still further, the cerium oxide abrasive grains may be abrasive grains containing only CeO2, or may be a mixture of abrasive grains with CeO2 as the main component. When the CeO2 is a mixture of abrasive grains, the content of CeO2 in the mixture of abrasive grains is at least 72 wt (weight) %, for example, the mixture of abrasive grains contains 72 wt (weight) %, 75 wt (weight) %, 78 wt (weight) %, 80 wt (weight) %, 83 wt (weight) %, 85 wt (weight) %, 89 wt (weight) %, 91 wt (weight) %, 93 wt (weight) %, 96 wt (weight) %, 98 wt (weight) %, 100 wt (weight) % of CeO2. In addition to the CeO2 abrasive grains in the mixture of abrasive grains, it may also include at least one metal oxide abrasive grain among aluminum oxide (aluminum oxide), silicon oxide (silicon dioxide), zirconium oxide (zirconium oxide), titanium oxide (titanium dioxide), germanium oxide (germanium oxide), magnesium oxide (magnesium oxide), nickel oxide, gallium oxide (gallium oxide), yttrium oxide (yttrium oxide). It should be noted that the cerium oxide abrasive grains in this composition preferably select cerium oxide abrasive grains of 100 wt (weight) % of CeO2.

[0035] In some embodiments, the cerium dioxide abrasive grains are doped cerium dioxide abrasive grains. Suitable dopants are, for example, metal ions (such as Ca, Mg, Zn, Zr, Sc, Y) or lanthanide elements (such as lanthanum, praseodymium, neodymium, promethium or samarium). However, it has been found that the abrasive grains of the present invention can exhibit a high removal rate even without dopants. Therefore, the cerium dioxide abrasive grains are substantially free of dopants. Dopants may be present as impurities in the abrasive grains, and the impurities may be derived from the raw materials or starting materials used to prepare the abrasive grains.

[0036] It should be noted that the CeO2 abrasive grains may contain impurities, which originate from the raw materials or processes for preparing the abrasive grains. These impurities can be considered not to be part of the abrasive grain mixture, that is, these impurities are not added as individual components to the composition. This means that the impurities are not added in a substantial amount. The non-substantial amount of the present invention is an amount less than 30 ppm, further less than 20 ppm, further less than 10 ppm, and further less than 1 ppm. Among them, the ppm refers to weight ppm. It should be noted that the cerium dioxide abrasive grains in the composition preferably do not contain impurities. For the convenience of presentation, the following description will be based on CeO2 abrasive grains with 100 wt (weight)% of the abrasive grains and no impurities.

[0037] The CeO2 abrasive grains should have a suitable morphology. The morphology of the CeO2 abrasive grains affects the surface reactivity of the CeO2 abrasive grains and affects the material removal rate. The morphology can be determined by those skilled in the art, for example, using transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images. It has been found that the CeO2 abrasive grains with a spherical morphology exhibit a lower material removal rate. Further, the amount of the CeO2 abrasive grains having a spherical morphology is at most 34.6 wt% of the CeO2 abrasive grains. For example, the amount of the CeO2 abrasive grains having a spherical morphology is 34.6 wt%, 24.9 wt%, 13.8 wt%, 6.8 wt%, 3.1 wt%, etc. of the abrasive grains. It should be noted that the spherical morphology is not limited to a perfect sphere, but refers to any circular morphology without substantial edges and vertices (corners), such as spherical, ellipsoidal, grape-like structures, etc.

[0038] It has been found that the CeO2 abrasive grains having at least one vertex can exhibit a higher material removal rate. Further, the CeO2 abrasive grains have a morphology selected from a cube, a quadrangular pyramid, a triangular prism, a dodecahedron, an icosahedron, an octahedron, a hexagonal pyramid, a hexagonal prism, a pentagonal prism, a cone, a tetrahedron, a cuboid, a rhombus, a hexagonal rhombus, and mixtures thereof.

[0039] In some embodiments, the CeO2 abrasive grains have a cubic morphology. It has been found that the CeO2 abrasive grains with a cubic morphology can exhibit a higher material removal rate. Herein, the cubic morphology refers to any cube-like morphology, not limited to a perfect cube. For example, one or more edges of the CeO2 abrasive grains can be slightly rounded, one or more vertices of the CeO2 abrasive grains can be slightly rounded, one or more opposite edges of the CeO2 abrasive grains can be slightly inclined (not completely parallel), one or more dihedral angles of the CeO2 abrasive grains can be slightly greater than or less than 90°, and other differences from a perfect cube. Slightly can refer to a deviation from a perfect cube of at most 30%, such as a deviation of 30%, 20%, 10%, etc. from a perfect cube. Further, the amount of the CeO2 abrasive grains having a cubic morphology is at least 31.3 wt% of the CeO2 abrasive grains. For example, the amount of the CeO2 abrasive grains having a cubic morphology is 31.3 wt (mass)%, 49.2 wt (mass)%, 68.4 wt (mass)%, 76.3 wt (mass)%, 86.7 wt (mass)%, 93.8 wt (mass)%, 98 wt (mass)%, etc. of the CeO2 abrasive grains.

[0040] The CeO2 abrasive grains can exist in the composition as single abrasive grains, aggregates, agglomerates, and mixtures thereof. Single abrasive grains can be attached to each other, for example, by van der Waals forces, thereby forming aggregates of more than one single abrasive grain. Aggregates themselves can be further attached to each other, for example, by physical interactions, to form agglomerates of more than one aggregate. The formation of aggregates and agglomerates is reversible. Herein, the CeO2 abrasive grains in this application include single abrasive grains, aggregates, and agglomerates. Among them, the number of single abrasive grains and aggregates and agglomerates can be determined by those skilled in the art through transmission electron microscopy (TEM) or scanning electron microscopy (SEM) images.

[0041] A large amount of aggregation and agglomeration of the single CeO2 abrasive grains in the composition will lead to a shortened shelf life of the electrochemomechanical polishing composition, and at the same time, more defects such as scratches and pits will appear on the surface of the SiC material. Therefore, in the composition, the content of the sum of the aggregates and agglomerates of the CeO2 abrasive grains is at most 68.9 wt (mass)%. For example, it can be 68.9 wt (mass)%, 56.7 wt (mass)%, 45.4 wt (mass)%, 32.3 wt (mass)%, 22.1 wt (mass)%, etc. In order to avoid defects on the surface of the SiC material to improve the polishing quality, it is necessary to reduce the aggregation and agglomeration of the CeO2 abrasive grains as much as possible.

[0042] There are many factors leading to the aggregation and agglomeration of the CeO2 abrasive grains. For example, the content of the CeO2 abrasive grains, the zeta potential of the CeO2 abrasive grains, the viscosity of the composition, etc. Among them, when the content of the CeO2 abrasive grains in the composition is too high, the distance between the CeO2 abrasive grains 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 CeO2 abrasive grains in the composition all carry the same kind of charge. That is to say, the lower the charge density on the surface of the CeO2 abrasive grains, the smaller the zeta potential, and the weaker the charge repulsion force between the abrasive grains, the easier it is for the abrasive grains to agglomerate. The higher the viscosity of the composition, the slower the movement of the CeO2 abrasive grains in the composition, and the easier it is for the CeO2 abrasive grains to aggregate and agglomerate.

[0043] Therefore, in order to avoid the aggregation of the CeO2 abrasive grains, the content of the CeO2 abrasive grains in the composition is at least 0.001 wt% by weight. For example, the content of the CeO2 abrasive grains 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%, 0.14 wt%. The content of the CeO2 abrasive grains in the composition is at most 21.7 wt% by weight. For example, the content of the CeO2 abrasive grains 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 CeO2 abrasive grains in the composition is from 0.03 wt% to 18.9 wt% by weight, and a suitable range can be selected according to requirements. For example, 0.03 wt% to 0.3 wt%, 0.03 wt% to 2 wt%, 0.03 wt% to 2.5 wt%, 0.03 wt% to 9.5 wt%, 0.03 wt% to 12.5 wt%, 0.03 wt% to 16 wt%, 0.03 wt% to 18 wt%, 0.03 wt% to 18.9 wt%, 0.3 wt% to 0.5 wt%, 0.3 wt% to 4 wt%, 0.3 wt% to 6.5 wt%, 0.3 wt% to 10 wt%, 0.3 wt% to 13.5 wt%, 0.3 wt% to 16.5 wt%, 0.3 wt% to 18.5 wt%, 0.5 wt% to 4 wt%, 0.5 wt% to 9 wt%, 0.5 wt% to 12.5 wt%, 0.5 wt% to 15.5 wt%, 0.5 wt% to 18 wt%, 0.75 wt% to 0.1 wt%, 0.75 wt% to 8 wt%, 0.75 wt% to 12 wt%, 0.75 wt% to 17 wt%, 1 wt% to 3.5 wt%, 1 wt% to 10 wt%, 1 wt% to 14.5 wt%, 1 wt% to 18.5 wt%, 1.5 wt% to 8 wt%, 1.5 wt% to 12 wt%, 1.5 wt% to 15.5 wt%, 1.5 wt% to 18.9 wt%, 2 wt% to 6 wt%, 2 wt% to 13 wt%, 2 wt% to 18 wt%, 2.5 wt% to 9.5 wt%, 2.5 wt% to 12.5 wt%, 2.5 wt% to 17 wt%, 3 wt% to 5.5 wt%, 3 wt% to 13.5 wt%, 3 wt% to 16.5 wt%, 3.5 wt% to 9.5 wt%, 4 wt% to 11.5 wt%, 4.5 wt% to 8 wt%, 4.5 wt% to 18 wt%, 5 wt% to 14 wt%, 5.5 wt% to 10 wt%, 5.5 wt% to 15.5 wt%, 6 wt% to 17 wt%, 6.5 wt% to 18 wt%, 7 wt% to 16 wt%, 7.5 wt% to 10.5 wt%, 8 wt% to 12.5 wt%, 8.5 wt% to 14.5 wt%, 9 wt% to 13 wt%, 10 wt% to 16 wt%, 11 wt% to 17 wt%, 11.5 wt% to 18.5 wt%, 12 wt% to 18 wt%, 12.5 wt% to 18.5 wt%, 13 wt% to 18 wt%, 13.5 wt% to 18.5 wt%, 14 wt% to 18.9 wt%, 14.5 wt% to 18.5 wt%, 15 wt% to 18 wt%, 15.5 wt% to 18 wt (by weight), 16 wt% to 18.9 wt%, 16.5 wt% to 18.5 wt%, 17 wt% to 18.5 wt%, 17.5 wt% to 18.5 wt%, 18 wt% to 18.9 wt%, 18.5 wt% to 18.9 wt%, and so on.

[0044] The content of the described CeO₂ abrasive grains can also be selected according to requirements. For example, by weight, it can be 0.03wt%, 0.06wt%, 0.09wt%, 0.14wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.33wt%, 0.39wt%, 0.42wt%, 0.46wt%, 0.5wt%, 0.54wt%, 0.58wt%, 0.63wt%, 0.7wt%, 0.75wt%, 0.79wt%, 0.82wt%, 0.86wt%, 0.90wt%, 1wt%, 1.2wt%, 1.3wt%, 1.5wt%, 1.8wt%, 2wt%, 2.5wt%, 2.8wt%, 3wt%, 3.3wt%, 3.8wt%, 4wt%, 4.2wt%, 4.5wt%, 4.8wt%, 5wt%, 5.3wt%, 5.5wt%, 5.8wt%, 6wt%, 6.3wt%, 6.6wt%, 6.9wt%, 7wt%, 7.3wt%, 7.5wt%, 7.8wt%, 8wt%, 8.2wt%, 8.6wt%, 8.9wt%, 9wt%, 9.3wt%, 9.5wt%, 9.8wt%, 10wt%, 10.2wt%, 10.5wt%, 10.9wt%, 11wt%, 11.3wt%, 11.7wt%, 11.9wt%, 12wt%, 12.3wt%, 12.5wt%, 12.8wt%, 13wt%, 13.3wt%, 13.6wt%, 13.9wt%, 14wt%, 14.2wt%, 14.8wt%, 15wt%, 15.3wt%, 15.5wt%, 15.9wt%, 16wt%, 16.5wt%, 16.8wt%, 17wt%, 17.4wt%, 17.8wt%, 18wt%, 18.4wt%, 18.6wt%, 18.9wt%, and so on.

[0045] In addition, the zeta potential can be used to reflect the charge density on the surface of the CeO₂ abrasive grains. The zeta potential can be measured by, for example, Mastersizer S (Malvern Instruments). As is known to those skilled in the art, the zeta potential refers to the potential at the interface between the moving fluid in the composition and the fluid stable layer attached to the abrasive grains dispersed in the composition. The higher the zeta potential, the stronger the electrostatic repulsion between the CeO₂ abrasive grains, and the better the stability of the composition. The zeta potential can be positive, negative, or equal to zero. There are many factors that affect the magnitude and sign of the zeta potential value, such as pH value, ion concentration, etc.

[0046] In the composition, the CeO2 abrasive grains are positively charged, that is, the zeta potential of the CeO2 abrasive grains is positive. For the CeO2 abrasive grains with a positively charged surface, the counterions in the diffusion layer are negative. When an acid (H + ) is added, the concentration of positive ions in the electrolyte increases, attracting the negative ions on the diffusion layer, and attracting more positive ions into the inner layer region, resulting in more positive charges, increasing the absolute value of the zeta potential, increasing the charge amount of the nano-abrasive grains and enhancing the repulsive force, making it more stable.

[0047] Among them, in order to increase the absolute value of the zeta potential, the pH value range of the composition can be 2 - 7, and a suitable range can be selected according to requirements. For example, 2 - 2.5, 2 - 3, 2 - 3.5, 2 - 4, 2 - 4.5, 2 - 5, 2 - 5.5, 2 - 6, 2 - 6.5, 2 - 7, 2.5 - 3, 2.5 - 3.5, 2.5 - 4, 2.5 - 4.5, 2.5 - 5, 2.5 - 5.5, 2.5 - 6, 2.5 - 6.5, 2.5 - 7, 3 - 3.5, 3 - 4, 3 - 4.5, 3 - 5, 3 - 5.5, 3 - 6, 3 - 6.5, 3 - 7, 3.5 - 4, 3.5 - 4.5, 3.5 - 5, 3.5 - 5.5, 3.5 - 6, 3.5 - 6.5, 3.5 - 7, 4 - 4.5, 4 - 5, 4 - 5.5, 4 - 6, 4 - 6.5, 4 - 7, 4.5 - 5, 4.5 - 5.5, 4.5 - 6, 4.5 - 6.5, 4.5 - 7, 5 - 5.5, 5 - 6, 5 - 6.5, 5 - 7, 5.5 - 6, 5.5 - 6.5, 5.5 - 7, 6 - 6.5, 6 - 7. A suitable pH value can also be selected according to requirements, such as 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, etc.

[0048] In order to achieve a better removal and polishing effect, the CeO2 abrasive grains have a zeta potential of at least 10 mV at a pH value of 3.5 - 4.5 in the composition, such as it can be 10 mV, 11 mV, 12 mV, 13 mV, 14 mV,

[0049] 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

[0050] The zeta potential of etc. The CeO2 abrasive grains have a zeta potential of at most 80 mV at a pH value of 3.5 - 4.5 in the composition, such as a zeta potential that can be 80 mV, 75 mV, 70 mV, 65 mV, 60 mV, 55 mV, 50 mV, 45 mV, 40 mV, 35 mV, etc. The CeO2 abrasive grains have a zeta potential of 25 mV to 80 mV, 11 mV to 75 mV, 35 mV to 75 mV, 21 mV to 70 mV, 16 mV to 65 mV, 45 mV to 65 mV, 26 mV to 60 mV, 15 mV to 55 mV, 34 mV to 55 mV, 27

[0051] to 50 mV, 30 mV to 45 mV, 18 mV to 40 mV, 11 mV to 35 mV, 23 mV to 35 mV,

[0052] a zeta potential of 15 mV to 30 mV, 12 mV to 25 mV, 17 mV to 25 mV, 12 mV to 20 mV, and so on.

[0053] It should be noted that the above pH values only exemplarily show the relationship between the pH value and the zeta potential, and the relationship between the pH value and the zeta potential in this application is not limited to the above situation. The two can be any combination of the above pH value range and zeta potential range. For example, the CeO2 abrasive grains have a zeta potential of at least 10 mV at a pH value of 2 - 7 in the composition, and the CeO2 abrasive grains have a zeta potential of at most 80 mV at a pH value of 2 - 7 in the composition; the CeO2 abrasive grains have a zeta potential of 15 mV - 75 mV at a pH value of 3 - 6 in the composition; the CeO2 abrasive grains have a zeta potential of 28 mV - 60 mV at a pH value of 3.5 - 5 in the composition, and so on. Examples are not listed one by one here.

[0054] The composition further includes the pH regulator to adjust the above pH value so that the zeta potential in the composition is at an appropriate value or range. Among them, the pH regulator can be an acid. Further, the acid can be an organic acid.

[0055] The organic acid includes at least one of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, methylbutyric acid, caproic acid, dimethylbutyric acid, ethylbutyric acid, methylvaleric acid, enanthic acid, methylcaproic acid, caprylic acid, ethylcaproic 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, furan carboxylic acid, tetrahydrofuran carboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, methanesulfonic acid, ethanesulfonic acid, sulfosuccinic acid, benzenesulfonic acid, toluenesulfonic acid, phenylphosphonic acid, hydroxyethyldiphosphonic acid.

[0056] 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, pimelic acid.

[0057] Regarding inorganic acids, the composition of the present invention does not contain inorganic acids. In the prior art, inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, phosphoric acid, etc. are usually used as pH regulators. However, the pH regulators of these inorganic acids will act on the surface of CeO2 abrasive grains and the material to be polished, thereby reducing the removal rate of the composition. Therefore, the present invention does not contain inorganic acids.

[0058] In addition, the composition further includes the pH buffer, and the pH buffer is used to help maintain the appropriate pH value of the composition. The pH buffer can be any suitable buffer. For example, the pH buffer can include at least one of phosphates, sulfates, acetates, borates, ammonium salts.

[0059] The composition further comprises a water-soluble polymer. The water-soluble polymer can be a homopolymer, a copolymer, or a combination thereof. The water-soluble polymer can be neutral, positively charged, or negatively charged in the composition. 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. Further, the water-soluble polymer can be freely soluble in water at 25°C. The water-soluble polymer can be at least one of polyvinylpyrrolidone, polyvinylacetamide, 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, blocked fatty alcohol alkoxylate, alkylene oxide ethylenediamine adduct, polyethyl oxazoline, polycarboxylic acid (such as polyacrylic acid), polyacrylate, polysulfonic acid (such as polyphosphonic acid, polystyrene sulfonic acid), polyvinyl alcohol, polyvinylpyrrolidone, sorbitan monooleate, oxyalkylene polymer, poly(2-hydroxyethyl methacrylate), poly(2-hydroxyethyl methacrylate), copolymer of poly(2-hydroxyethyl methacrylate), copolymer of poly(2-hydroxyethyl methacrylate), polysaccharide, cellulose derivative (such as hydroxypropyl cellulose, hydroxyethyl cellulose), methacryloyloxyethyltrimethylammonium, synthetic polymer (such as xanthan gum, sodium alginate). Further, the water-soluble polymer is a nonionic homopolymer. Further still, the water-soluble nonionic homopolymer is a polyether.

[0060] 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 10 g / mol. For example, the water-soluble polymer has a molecular weight of 10 g / mol, 20 g / mol, 40 g / mol, 60 g / mol, 80 g / mol. It has been found that high-molecular-weight water-soluble polymers will reduce the material removal rate during the ECMP process. Surprisingly, it has been found that low-molecular-weight water-soluble polymers can achieve fewer defects on the material surface while achieving a high SiC material removal rate during the ECMP process. Therefore, the water-soluble polymer has a molecular weight of at most 17,000 g / mol. For example, the water-soluble polymer has a molecular weight of 17,000 g / mol, 13,000 g / mol, 10,000 g / mol, 7,500 g / mol, 5,000 g / mol, 4,000 g / mol. In some embodiments, the molecular weight of the water-soluble polymer is from 10 g / mol to 17,000 g / mol, from 20 g / mol to 13,000 g / mol, from 40 g / mol to 10,000 g / mol, from 60 g / mol to 75000 g / mol, from 80 g / mol to 5,000 g / mol.

[0061] In use, the composition comprises at least 0.0001 wt% of the water-soluble polymer. For example, the composition comprises 0.0001 wt%, 0.001 wt%, 0.007 wt%, 0.013 wt%, 0.021 wt% of the water-soluble polymer. However, the amount of the water-soluble polymer should not be too high because it will reduce the removal rate of the SiC material. Therefore, in use, the composition comprises at most 9.7 wt% of the water-soluble polymer. For example, the composition comprises 9.7 wt%, 4.4 wt%, 2.3 wt%, 1.2 wt%, 0.14 wt% of the water-soluble polymer. In some embodiments, in use, the composition comprises from 0.0001 wt% to 9.7 wt%, from 0.001 wt% to 4.4 wt%, from 0.007 wt% to 2.3 wt%, from 0.013 wt% to 1.2 wt% of the water-soluble polymer.

[0062] The composition should have a suitable viscosity. The viscosity can be measured using an NDJ-8S viscometer (Shanghai Lichen Instrument Technology Co., Ltd.) at 25 °C in mPa*s (millipascal seconds). A higher viscosity can reduce the aggregation and agglomeration of abrasive grains, 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, 0.72 mPa*s, when measured as a 2% solution at 25 °C. However, if the viscosity is too high, the movement of the abrasive grains and other components other than the abrasive grains in the composition will be restricted, and the CeO2 abrasive grains are more likely to aggregate and agglomerate, resulting in a decrease in the 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, 7.8 mPa*s when measured as a 2% solution at 25 °C.

[0063] In addition to the polishing quality, the polishing efficiency is also a major factor affecting the effect of electrochemical mechanical polishing. The electrochemical mechanical polishing process in this application mainly consists of two steps. One is electrochemical anodic oxidation, that is, the surface of the SiC material is oxidized to form a SiO2 molecular oxide layer. The other is that the CeO2 abrasive grains mechanically polish the SiO2 molecular oxide layer. That is, there are oxygen vacancies on the surface of the CeO2 abrasive grains, which can form Ce-O-Si bonds with the generated SiO2 molecules and weaken the Si-O-Si bonds between the SiO2 molecules. Then, under the mechanical action of the CeO2 abrasive grains, the Si-O-Si bonds are broken, realizing the removal and polishing of the SiO2 molecular oxide layer by the CeO2 abrasive grains, and further realizing the polishing of the SiC material. From the above steps, it can be seen that the main rate-limiting steps for polishing the SiC material using the ECMP method are the oxidation of the surface of the SiC material and the polishing of the SiO2 molecular oxide layer by the CeO2 abrasive grains.

[0064] Regarding the oxidizing agent, the composition is substantially free of oxidizing agents. Hydrogen peroxide and sodium hypochlorite are commonly used as oxidizing agents in the prior art. However, when the oxidizing agent is added to the composition, it will react with the CeO2 abrasive grains, occupy the oxygen vacancies of the CeO2 abrasive grains, 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 their complexes (such as nitric acid, iron nitrate, silver nitrate, aluminum nitrate, ammonium cerium 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), ferrate(III) acid and its salts (such as ferrate(III) 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), the composition and its derivatives.

[0065] There are many factors that affect the oxidation rate of the SiC material surface, such as electrolytes. Among them, the electrolyte can enhance the conductivity of the composition, thereby enhancing the oxidation rate of the SiC material surface, and thus improving the removal rate.

[0066] In the composition, there is no concentration gradient. When an electric current is applied, the current can only be transmitted through ion migration. Adding an electrolyte to the composition will increase the ion concentration, reduce the resistance of the composition, and thus increase the conductivity of the composition. Further, 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, 1 mS / cm. Even further, 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, 10 mS / cm.

[0067] It should be noted that the above pH values only exemplarily show the relationship between the pH value and the conductivity. In this application, the relationship between the pH value and the conductivity is not limited to the above situation. The two can be any combination of the pH value range and the conductivity range mentioned in this application. For example, the conductivity of the composition is at least 1 mS / cm at a pH value of 2 - 7; the conductivity of the composition is at least 1 mS / cm at a pH value of 3 - 6; the conductivity of the composition is at least 1 mS / cm at a pH value of 3 - 4.5; the conductivity of the composition is at least 1 mS / cm at a pH value of 4 - 5, etc. Examples are not listed one by one here.

[0068] The electrolyte in the composition can be an organic electrolyte. Further, the electrolyte can be an organic acid salt.

[0069] Among them, the metal ions can include alkali metal ions, alkaline earth metal ions and ammonium ions. The alkali metal ions can include lithium (Li + ), sodium (Na + ), potassium (K + ), rubidium (Rb + ), and cesium (Cs + ). The alkaline earth metal ions can be beryllium (Be 2+ ), magnesium (Mg 2 + ), calcium (Ca 2+ ), strontium (Sr 2+ ), barium (Ba 2+ ), radium (Ra 2+ ). The ammonium ion can be NH4 + . Further, the metal ion is an alkali metal ion.

[0070] Studies have found that more than one acid group can reduce the zeta potential of cerium dioxide abrasive particles or reverse the charge of cerium dioxide abrasive particles to a negative charge, thereby greatly reducing the material removal rate and causing adverse defects such as particle aggregation and scratches on the substrate surface. Organic acids have at most three acid groups, further at most two acid groups, and still further one acid group. In some embodiments, the organic acid is an organic monoacid. In some embodiments, the ECMP composition does not contain an organic electrolyte having more than one acid group. For example, unsuitable organic electrolytes can 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, sodium glutarate, magnesium glutarate, calcium glutarate, potassium pyrogalate, sodium pyrogalate, magnesium pyrogalate, calcium pyrogalate, bisulfates (such as potassium bisulfate, sodium bisulfate), pyrosulfates (such as potassium pyrosulfate), methanesulfonates (such as sodium methanesulfonate, potassium methanesulfonate), ethanephosphates (such as sodium ethanephosphate, potassium ethanephosphate), triphosphates (such as sodium triphosphate, potassium triphosphate), tetraphosphates (such as sodium tetraphosphate), diborates (such as sodium diborate), tetraborates (such as sodium tetraborate, commonly known as borax), or combinations thereof.

[0071] The organic acid providing the organic acid radical can be a monobasic acid, thereby forming an organic monoacid salt. The monobasic acid is an organic compound having one acid group. The monobasic acid can be in the form of an acid, a conjugate acid, a salt, or a combination thereof. Suitable acid groups are, for example, carboxyl group, sulfonic acid group, and phosphonic acid group. Further, the monobasic acid can be a monocarboxylic acid. The monocarboxylic acid can be a straight-chain monocarboxylic acid, a branched-chain monocarboxylic acid, a saturated monocarboxylic acid, an unsaturated monocarboxylic acid, a substituted monocarboxylic acid, an aromatic monocarboxylic acid, or a combination thereof.

[0072] The monocarboxylic acid may be at least one of nicotinic acid, isonicotinic acid, quinolinic acid, acetic acid, picolinic acid, hydroxybenzoic acid, formic acid, carbonic acid, glycolic acid, glyoxylic acid, lactic acid, glyceric acid, pyruvic acid, oxopropionic acid, hydroxypropionic acid, oxopropionic acid, glyceric acid, butyric acid, isobutyric acid, butyric acid, butyric acid, propionic acid, butyric acid, isocaprylic acid, isocaprylic acid, acrylic acid, methacrylic acid, vinylacetic acid, tetranitric acid, hydroxybutyric acid, oxobutyric acid, valeric acid, isovaleric acid, valeric acid, caproic acid, sorbic acid, benzoic acid, salicylic acid, caprylic acid, pelargonic acid, cinnamic acid, capric acid, myristic acid, palmitic acid, stearic acid, oxalic acid, propionic acid, propionic acid, hydroxypropionic acid, oxopropionic acid, dioxopropionic 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-hydroxy-β-methylbutyric acid, furan acid, tetrahydrofuran acid, dimethylbutyric acid, dimethylbutyric acid, heptanoic acid, cyclohexanecarboxylic acid, dimethylvaleric acid, ethylvaleric acid, methylcaproic acid, trimethylbutyric acid, ethylmethylbutyric acid, methylheptanoic acid, methylheptanoic acid, dimethylcaproic acid, ethylcaproic acid, caprylic acid, undecanoic acid, lauric acid, tricyclic acid, pentadecanoic acid, margaric acid, oleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid, stearic acid.

[0073] Further, the organic acid radical in the organic salt may be a monovalent organic acid radical with a single negative charge. For example, the organic acid providing the organic acid radical may 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, propiolic acid, thereby forming at least one organic mono-salt such as isonicotinate, glycolate, hydroxypropionate, butyrate, isobutyrate, butyrate, propionate, acetate, valerate, sorbate, propiolate. The metal ion in the organic salt may be a monovalent metal ion with a single positive charge. For example, the metal ion is sodium (Na + ) and / or potassium (K + ). The organic acid salts 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, potassium propiolate.

[0074] When in use, an excessively high electrolyte concentration will cause the CeO2 abrasive to aggregate, reduce the removal rate of the CeO2 abrasive, and shorten the shelf life of the CeO2 abrasive. Therefore, it is necessary to select a suitable electrolyte concentration. Further, 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%, 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%, 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.

[0075] 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 caproate, 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.

[0076] The composition is substantially free of inorganic electrolytes. In addition, the use of inappropriate electrolytes (such as inorganic electrolytes) will reduce or reverse the zeta potential of the CeO2 abrasive grains, resulting in the aggregation of the CeO2 abrasive grains, 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 polyacid salts or polyhydroxy salts, and the presence of polyacid salts 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 (such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride), hypochlorites (such as potassium hypochlorite, sodium hypochlorite, calcium hypochlorite), perchlorates (such as potassium perchlorate, sodium perchlorate, magnesium perchlorate), nitrates (such as potassium nitrate, sodium nitrate, magnesium nitrate, calcium nitrate), nitrites (such as sodium nitrite, potassium nitrite, magnesium nitrite), sulfates (such as sodium sulfate, potassium sulfate, magnesium sulfate (English name: Epsom salt), calcium sulfate (gypsum)), phosphates (such as sodium phosphate, potassium phosphate, magnesium phosphate, calcium phosphate), phosphates (such as sodium dihydrogen phosphate, potassium dihydrogen phosphate, magnesium dihydrogen phosphate), chlorates (such as potassium chlorate, sodium chlorate, magnesium chlorate), bromates (such as potassium bromate, sodium bromate, magnesium bromate, calcium bromate), iodates (such as sodium iodate, potassium iodate, calcium iodate), borates (such as sodium borate, potassium borate, magnesium borate, calcium borate), peroxide salts (such as potassium perbromate, sodium perbromate, potassium periodate, sodium periodate), carbonates (such as sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate), bicarbonates (such as sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate), fluorides (such as sodium fluoride, potassium fluoride, calcium fluoride), permanganates (such as potassium permanganate, sodium permanganate), thiosulfates (such as sodium thiosulfate, potassium thiosulfate), oxalates (such as sodium oxalate, potassium oxalate, calcium oxalate), and combinations thereof.

[0077] In addition to the above factors, the removal rate enhancer also affects the polishing rate of the CeO2 abrasive grains on the SiO2 molecular oxide layer. The removal rate enhancer can improve the material removal rate by interacting with the surface of the SiC material.

[0078] Further, the removal rate enhancer may be an amino acid. The amino acid may be a protein amino acid and / or a non-protein amino acid. Among them, the protein amino acid may 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, pyrrolysine. The non-protein amino acid may be at least one of ornithine, citrulline, carnitine, γ-aminobutyric acid, levothyroxine, β-alanine, aminoisobutyric acid.

[0079] Furthermore, the amino acid is a protein amino acid. In some embodiments, the molecular weight of the amino acid is at most 150 g / mol, for example, it may be 150 g / mol, 140 g / mol, 130 g / mol, 120 g / mol, and so on.

[0080] In use, the composition contains at least 0.002 wt% of amino acid. For example, the composition may contain 0.002 wt%, 0.02 wt%, 0.12 wt%, 0.28 wt%, 0.46 wt% of amino acid. At the same time, the composition contains at most 18.3 wt% of amino acid. For example, the composition may contain 18.3 wt%, 9.8 wt%, 6.3 wt%, 4.3 wt%, 2.9 wt% of amino acid. In some embodiments, the composition contains 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 acid. In addition, adding appropriate types and appropriate ranges of amino acids can not only enhance the removal rate of the material, but also reduce the number of defects in the material during the ECMP treatment process.

[0081] The composition may further contain one or more biocides. The biocide may be a compound that prevents, inhibits, reduces growth, inhibits activity or eliminates unwanted microorganisms. Examples of biocides are sodium hypochlorite, methylisothiazolinone, benzisothiazolone, chloromethylisothiazolinone and combinations thereof.

[0082] The composition contains at least 0.6 ppm by weight. For example, the composition contains 0.6 ppm, 1.6 ppm, 2.7 ppm, 3.8 ppm, 4.6 ppm by wt of biocide. High concentrations of biocides can cause unwanted interactions between the biocide and other components of the composition as well as the material. Therefore, the composition contains at most 98 ppm by wt. For example, the composition contains 98 ppm, 83 ppm, 74 ppm, 69 ppm by wt of biocide.

[0083] It should be noted that in some embodiments, the biocide may not be added to the composition. In this case, the composition may also exhibit an advantageous high material removal rate.

[0084] In addition, there are many factors that affect the polishing rate of the CeO2 abrasive grains on the SiO2 molecular oxide layer, such as particle size, lattice parameter of the CeO2 abrasive grains, band gap of the CeO2 abrasive grains, width of the F 2g peak, removal rate enhancer, etc. The particle size may include the average particle size and the width of the particle size distribution. If the average particle size is too large, a large number of defects such as scratches and pits will appear on the surface of the SiC material; if the average particle size is too small, the material removal rate will decrease. An appropriate particle size distribution can increase the abrasive grain packing density on the material surface (reduce the volume of 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 CeO2 abrasive grains and the material surface, thereby increasing the polishing rate of the CeO2 abrasive grains and further improving the removal rate.

[0085] As is known to those skilled in the art, the average particle size can be obtained by laser diffraction measurement (for example, using LA-960 from Horiba). The curve graph obtained through the measurement provides the cumulative volume percentage of the CeO2 abrasive grains with a certain size. All particle sizes mentioned herein (such as D01, D30, D50, D70, D99, z-average particle size) refer to the particle size of the abrasive grains in the ECMP composition.

[0086] 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 the LA-960 from Horiba). The CeO2 abrasive grains have a suitable z-average particle size. A smaller z-average particle size will result in a lower material removal rate. The CeO2 abrasive grains have a z-average particle size of at least 10 nm as measured by laser diffraction. For example, the CeO2 abrasive grains have a z-average particle size of 10 nm, 20 nm, 30 nm, 40 nm, 45 nm, 50 nm as measured by laser diffraction. Further, the CeO2 abrasive grains have 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 SiC material during the ECMP process. The CeO2 abrasive grains have a z-average particle size of at most 500 nm as measured by laser diffraction. For example, the CeO2 abrasive grains 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, 90 nm as measured by laser diffraction. Further, the CeO2 abrasive grains have a z-average particle size of at most 90 nm as measured by laser diffraction. In some embodiments, the CeO2 abrasive grains 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, 50 nm to 90 nm as measured by laser diffraction.

[0087] D50 is the particle size at which 50% by volume of the CeO2 abrasive grains have a particle size less than the value. A smaller D50 will result in a lower material removal rate. The cerium oxide abrasive grains have a D50 of at least 5 nm as measured by laser diffraction. For example, the cerium oxide abrasive grains have a D50 of 5 nm, 10 nm, 20 nm, 30 nm, 35 nm, 40 nm, 45 nm as measured by laser diffraction. Further, the cerium oxide abrasive grains have a D50 of at least 45 nm as measured by laser diffraction. However, if the D50 is too large, during the ECMP process, a large number of unwanted defects such as scratches will appear on the surface of the SiC material. Therefore, the CeO2 abrasive grains should have a smaller average particle size. The cerium oxide abrasive grains have a D50 of at most 400 nm as measured by laser diffraction. For example, the cerium oxide abrasive grains have a D50 of 400 nm, 300 nm, 200 nm, 150 nm, 100 nm, 95 nm, 90 nm as measured by laser diffraction. Further, the cerium oxide abrasive grains have a D50 of at most 90 nm as measured by laser diffraction. In some embodiments, the cerium oxide abrasive grains 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, 45 nm to 90 nm as measured by laser diffraction. It is generally believed that the CeO2 abrasive grains with a larger D50 will result in a higher material removal rate during the ECMP process. However, surprisingly, it has been found that the CeO2 abrasive grains of the present invention can achieve a high material removal rate even with a smaller D50.

[0088] D01 is the particle size at which 1% by volume of the abrasive grains have a particle size less than the value. Among them, the cerium oxide abrasive grains have a D01 of at least 2 nm as measured by laser diffraction. For example, 2 nm, 7 nm, 13 nm, 15 nm, 26 nm, 28 nm of D01. A smaller D01 of the abrasive grains will increase the packing density of the CeO2 abrasive grains on the surface of the SiC material during the ECMP process (reduce the void volume), which helps to improve the material removal rate. Further, the cerium oxide abrasive grains have a D01 of at most 150 nm as measured by laser diffraction. For example, the cerium oxide abrasive grains have a D01 of 150 nm, 120 nm, 100 nm, 90 nm, 80 nm, 70 nm as measured by laser diffraction. In some embodiments, the cerium oxide abrasive grains 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, 28 nm to 70 nm as measured by laser diffraction.

[0089] D30 is the particle size at which 30 volume % of the CeO2 abrasive grains are smaller than said value. Among them, the CeO2 abrasive grains have a laser diffraction measurement of at least 3 nm. For example, the CeO2 abrasive grains have a laser diffraction measurement of 3 nm, 10 nm, 15 nm, 20 nm, 30 nm, 35 nm. A smaller D30 of the CeO2 abrasive grains will increase the packing density (reduce the void volume) of the CeO2 abrasive grains on the material surface during the ECMP process, which helps to improve the material removal rate. Further, the CeO2 abrasive grains have a laser diffraction measurement of at most 350 nm. For example, the CeO2 abrasive grains have a laser diffraction measurement of 350 nm, 300 nm, 200 nm, 100 nm, 90 nm, 80 nm for D30. In some embodiments, the CeO2 abrasive grains have a laser diffraction measurement of D30 from 3 nm to 350 nm, from 10 nm to 300 nm, from 15 nm to 200 nm, from 20 nm to 100 nm, from 30 nm to 90 nm, from 35 nm to 80 nm.

[0090] D70 is the particle size at which 70 volume % of the CeO2 abrasive grains are smaller than said value. A higher D70 of the CeO2 abrasive grains will increase the material removal rate during the ECMP process. Among them, the CeO2 abrasive grains have a laser diffraction measurement of at least 16 nm. For example, the CeO2 abrasive grains have a laser diffraction measurement of at least 16 nm, 18 nm, 24 nm, 30 nm, 40 nm, 50 nm for D70. However, if the D70 of the CeO2 abrasive grains is too high, more undesirable defects such as scratches will appear during the ECMP process. Therefore, the CeO2 abrasive grains have a laser diffraction measurement of at most 421 nm. For example, the CeO2 abrasive grains have a laser diffraction measurement of 421 nm, 376 nm, 269 nm, 218 nm, 194 nm, 160 nm for D70. In some embodiments, the CeO2 abrasive grains have a laser diffraction measurement of D70 from 16 nm to 421 nm, from 18 nm to 376 nm, from 24 nm to 269 nm, from 30 nm to 218 nm, from 40 nm to 194 nm, from 50 nm to 160 nm.

[0091] D99 is the particle size at which 99% by volume of the CeO₂ abrasive grains have a particle size smaller than the value. A higher D99 of the CeO₂ abrasive grains will increase the material removal rate during the ECMP process. Among them, the CeO₂ abrasive grains have a D99 measured by laser diffraction of at least 50 nm. For example, the CeO₂ abrasive grains have a D99 measured by laser diffraction of 50 nm, 70 nm, 80 nm, 90 nm, 100 nm. However, if the D99 of the CeO₂ abrasive grains is too high, more undesirable defects such as scratches will appear during the ECMP process. Therefore, the CeO₂ abrasive grains have a D99 measured by laser diffraction of at most 730 nm. For example, the CeO₂ abrasive grains have a D99 measured by laser diffraction of 730 nm, 600 nm, 450 nm, 300 nm, 194 nm. In some embodiments, the CeO₂ abrasive grains have a D99 measured by laser diffraction of 70 nm to 600 nm, 80 nm to 450 nm, 90 nm to 300 nm, 100 nm to 194 nm.

[0092] Generally, a wider particle size distribution results in a higher material removal rate because there are more of the larger CeO₂ abrasive grains and the CeO₂ abrasive grains are better loaded during the ECMP process. However, a wider particle size distribution is generally associated with a larger number of defects in the material surface. Among them, the CeO₂ abrasive grains of the present application can increase the material removal rate even with a narrow particle size distribution.

[0093] The CeO₂ abrasive grains should have a large steepness factor. 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 CeO₂ abrasive grains have a particle size smaller than the value. D70 is the particle size at which 70% by volume of the CeO₂ abrasive grains have a particle size smaller than the value. A wider particle size distribution provides a small steepness factor, while a narrower particle size distribution provides a large steepness factor. Among them, the CeO₂ abrasive grains of the present invention with a large steepness factor exhibit a high material removal rate while achieving fewer defects such as scratches in the material during the ECMP process. Further, the CeO₂ abrasive grains have a steepness factor of at least 34. For example, the CeO₂ abrasive grains have steepness factors of 34, 40, 45, 50, 60, 70, 78. However, if the steepness factor is too large, the material removal rate will decrease during the ECMP process. Therefore, the CeO₂ abrasive grains have a steepness factor of at most 98. For example, the CeO₂ abrasive grains have steepness factors of 98, 97, 96, 95.

[0094] The CeO2 abrasive grains should have a small slope factor. As used herein, the term slope factor refers to the absolute value of the ascending slope of the particle size distribution plot divided by the descending slope (meaning regardless of its sign). As is known to those skilled in the art, the particle size distribution plot can be obtained from particle size distribution measurements as described above, where the volume percentage of CeO2 abrasive grains (y-axis) is plotted against the particle size (x-axis). The term ascending slope as used herein refers to the slope of the tangent (straight line) drawn from P_D01 to P_max. The term descending 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 on the particle size distribution plot where the particle size is equal to D01. D01 is the particle size obtained by laser diffraction as described above, and 1 volume% of the CeO2 abrasive grains have a particle size less than D01. P_D99 refers to the point on the particle size distribution plot where the particle size is equal to D99. D99 is the particle size obtained by laser diffraction as described above, and 99 volume% of the CeO2 abrasive grains have a particle size less than D99. P_max refers to the absolute maximum of the particle size distribution plot, i.e., the point on the particle size distribution plot with the largest volume% of the CeO2 abrasive grains. A smaller slope factor can be, for example, the result of the distribution of the smaller CeO2 abrasive grains being wider than that of the larger CeO2 abrasive grains, which improves the packing of the CeO2 abrasive grains during the ECMP process. It has been found that a smaller slope factor results in fewer defects in the material while still exhibiting a high material removal rate. Further, the CeO2 abrasive grains have a slope factor of at most 400, for example, the CeO2 abrasive grains have slope factors of 400, 300, 200, 150, 90, 50, 30, 20, 10.

[0095] During the synthesis of the CeO2 abrasive grains, microcrystals are formed in the CeO2 abrasive grains. A microcrystal can be a region of a crystal or a crystal structure. The microcrystals can be located anywhere within the CeO2 abrasive grains, for example, at the center of the CeO2 abrasive grains or exposed on the surface of the CeO2 abrasive grains. One CeO2 abrasive grain can contain a single microcrystal, two microcrystals, or multiple microcrystals. By controlling the conditions during the synthesis of the CeO2 abrasive grains, such as temperature, the desired number and size of microcrystals in the CeO2 abrasive grains can be obtained.

[0096] The CeO2 abrasive grains should have a high crystallinity. The term crystallinity as used herein refers to the volume percentage of microcrystals contained in the CeO2 abrasive grains. By controlling parameters during the synthesis process of the CeO2 abrasive grains, such as temperature, an appropriate crystallinity can be obtained. As is known to those skilled in the art, the crystallinity can be obtained from the dried powder of the CeO2 abrasive grains by X-ray diffraction (XRD), for example, using a D8 X-ray diffractometer (Bruker Corp). It has been found that a higher crystallinity results in a higher material removal rate of the material during the ECMP process. Therefore, the CeO2 abrasive grains have at least 56% by volume. For example, the CeO2 abrasive grains have a crystallinity of 56% by volume, 78% by volume, 86% by volume, 96% by volume of the CeO2 abrasive grains. In some embodiments, the CeO2 abrasive grains are single microcrystals.

[0097] The CeO2 abrasive grains should have a coefficient of linear thermal expansion (CTELP) with appropriate lattice parameters. CTELP refers to the expansion of the atomic spacing within the CeO2 abrasive grains 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 is known to those skilled in the art, CTELP can be calculated from the slope of the curve of the 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 from 20°C to 400°C. It has been surprisingly found that a higher CTELP increases the material removal rate of the material during the ECMP process. Therefore, the CeO2 abrasive grains have at least For example, the CeO2 abrasive grains have CTELP at a particle size of 40 nm. Further, the CeO2 abrasive grains have at most For example, the CeO2 abrasive grains have CTELP at a particle size of 40 nm. In some embodiments, the CeO2 abrasive grains have to to to CTELP at a particle size of 40 nm.

[0098] The CeO2 abrasive grains may have lattice planes exposed on the surface of the abrasive grains, such as {100}, {110}, {111}, {220}, {422}, and combinations thereof. The desired lattice planes can be achieved, for example, by appropriate abrasive grain shapes, abrasive grain sizes, and parameters (such as temperature) during the synthesis of the CeO2 abrasive grains. As is known to those skilled in the art, lattice planes can be measured by X-ray diffraction, for example, by measuring the dry powder of the CeO2 abrasive grains with a D8 X-ray diffractometer (Bruker Corp). Compared with other lattice planes such as {111} and {110} exposed on the surface of the CeO2 abrasive grains, the lattice plane {100} exposed on the surface of the CeO2 abrasive grains results in more oxygen vacancies. More oxygen vacancies on the surface of the CeO2 abrasive grains can increase the movement of oxygen atoms within the microcrystals, which can increase the surface reactivity of the abrasive grains. It has been found that a higher percentage of the lattice plane {100} exposed on the surface of the CeO2 abrasive grains can increase the material removal rate of the material during the ECMP process. In some embodiments, at least 26% of the lattice planes exposed on the surface of the CeO2 abrasive grains, such as 26%, 42%, 52%, 64%, 71%, 83%, 94% of the lattice planes exposed on the surface of the CeO2 abrasive grains, are {100}. Further, at least 94% of the lattice planes exposed on the surface of the CeO2 abrasive grains.

[0099] The CeO2 abrasive grains should have a suitable lattice parameter a. The lattice parameter a refers to the average (arithmetic mean) length of the unit cell along the x-axis direction within the lattice of the abrasive grains. As is known to those skilled in the art, the lattice parameter can be obtained by X-ray diffraction, for example, with a D8 X-ray diffractometer (Bruker Corp), and calculated from each reflection (hkl) relative to cos 2 θ. A suitable lattice parameter a can induce favorable mechanical stress within the abrasive grains. Among them, the CeO2 abrasive grains have at least a lattice parameter a at a particle size of 40 nm, for example, the CeO2 abrasive grains have a lattice parameter a at a particle size of 40 nm. The CeO2 abrasive grains have at least a lattice parameter a at a particle size of 40 nm, for example, the CeO2 abrasive grains have a lattice parameter a.

[0100] The CeO2 abrasive grains have a low bandgap E g . As is known to those skilled in the art, the bandgap E g refers to the minimum energy required to excite an electron from the valence band to the conduction band. The bandgap E gIt can be obtained from the ultraviolet-visible (UV-Vis) absorption spectrum of a 1 wt% solution of the abrasive grains. For example, at 25 °C, using a Varian Cary 5E spectrophotometer (Agilent Technologies), the wavelength is scanned from 300 to 1000 nm. Based on the UV-Vis absorption spectrum, a Tauc curve can be plotted with (αhν)² (Y-axis) and (hγ) (X-axis), where α is the linear absorption coefficient, h is Planck's constant, and ν is the frequency of light. The linear part of the graph can be extrapolated, and the intersection with the extrapolated X-axis corresponds to the bandgap E g . A smaller bandgap E g will lead to an increase in the formation of reactive oxygen species (ROS) such as superoxide, singlet oxygen, hydroxyl radicals, and hydrogen peroxide. ROS may contribute to higher surface reactivity during the ECMP process. It was found that a lower bandgap E g may be related to a higher material removal rate during the ECMP process. Therefore, the CeO₂ abrasive grains have a bandgap E g of at most 3.40 eV. For example, the CeO₂ abrasive grains have bandgaps of 3.40 eV, 3.34 eV, 3.31 eV, 3.27 eV, 3.20 eV, 3.11 eV. Further, the abrasive grains have a bandgap E g of at least 2.36 eV. For example, the CeO₂ abrasive grains have bandgaps of at least 2.36 eV, 2.40 eV, 2.46 eV, 2.51 eV, 2.57 eV. g . The CeO₂ abrasive grains have bandgaps of 2.36 eV to 3.40 eV, 2.40 eV to 3.34 eV, 2.46 eV to 3.31 eV, 2.51 eV to 3.27 eV, 2.57 eV to 3.20 eV. g . A smaller bandgap E g can be achieved through a suitable particle size distribution, particle morphology, and microcrystalline structure of the abrasive grains.

[0101] The CeO₂ abrasive grains have a narrow F 2g peak evaluated by visible Raman spectroscopy. The visible Raman spectrum can be obtained, for example, at 25 °C using an FRS27 Raman spectrometer (Bruker Corp) with a 532 nm laser on the dry powder of the CeO₂ abrasive grains. As is known to those skilled in the art, the F 2g peak appears around 464 cm -1 and corresponds to Ce-O vibrations. The Raman spectrum should be baseline corrected and normalized to the intensity of the F 2g peak. The full width at half maximum (FWHM) can be used to describe the width of the F 2g peak at half of its maximum height. The FWHM is the F 2gThe peak intensity is the wavelength difference when it is half of the maximum intensity of the visible Raman spectrum measured at 532 nm. A smaller FWHM is related to a larger microcrystalline size of the CeO2 abrasive grains. In addition, a smaller number of defect sites contributes to reducing the FWHM. Crystal surface defects affect the oxygen mobility within the microcrystals and can change the surface reactivity during the ECMP process. Among them, a smaller FWHM can increase the removal rate of the SiC material. Therefore, the CeO2 abrasive grains have an FWHM measured at a wavelength of 532 nm of at most 58 cm -1 , for example, the CeO2 abrasive grains have an FWHM measured at a wavelength of 532 nm of 58 cm -1 、50 cm -1 、45 cm -1 、42 cm -1 、40 cm -1 、35 cm -1 、30 cm -1 、28 cm -1 、25 cm -1 、20 cm -1 、15 cm -1 、13 cm -1 、11 cm -1 of the F 2g peak.

[0102] The full width at one-third of the maximum peak (FWTM) can be used to describe the width of the F 2g peak at the lower part of the peak. FWTM is the wavelength difference when the F 2g peak intensity is one-third of the maximum intensity of the visible Raman spectrum measured at 532 nm. A smaller FWTM value is related to a larger abrasive grain microcrystalline size and the presence of crystal surface defects. Among them, a smaller FWTM can increase the removal rate of the SiC material. Therefore, the CeO2 abrasive grains have an FWTM measured at a wavelength of 532 nm of at most 65 cm -1 , for example, the CeO2 abrasive grains have an FWTM measured at a wavelength of 532 nm of at most 65 cm -1 、63 cm -1 、60 cm -1 、55 cm -1 、50 cm -1 、45 cm -1 、40 cm -1 、35 cm -1 、30 cm -1 、25 cm -1 、23 cm -1 、21 cm -1 of the F 2g peak.

[0103] The CeO2 abrasive grains should have a high ratio of D50 to FWHM. The ratio of D50 to FWHM is the absolute value of D50 of the CeO2 abrasive grains divided by the absolute value of the FWHM of the F 2g peak of the CeO2 abrasive grains measured by Raman spectroscopy at a wavelength of 532 nm. The D50 and F 2g of the FWHM of the peak of the CeO2 abrasive grains can be obtained as described above. A higher ratio of D50 to FWHM is related to a larger microcrystalline size relative to the abrasive grain size. A smaller number of crystal plane defects also helps to increase the ratio of D50 to F 2g of the FWHM of the peak. It has been found that a higher ratio of D50 to F 2g of the FWHM of the peak can be related to an increase in the material removal rate of the material during the ECMP process. Therefore, the CeO2 abrasive grains have a ratio of D50 to the FWHM of the F 2g peak measured by Raman spectroscopy at a wavelength of 532 nm of at least 4.51. For example, the CeO2 abrasive grains have ratios of D50 to the FWHM of the F 2g peak measured by Raman spectroscopy at a wavelength of 532 nm of 4.51, 5.12, 5.72, 6.1, 6.68. The CeO2 abrasive grains should have a high ratio of D50 to FWTM. The ratio of D50 to FWTM is the absolute value of D50 of the CeO2 abrasive grains divided by the FWTM of the F 2g peak of the CeO2 abrasive grains measured by Raman spectroscopy at a wavelength of 532 nm. The D50 and F 2g of the FWTM of the peak of the CeO2 abrasive grains can be obtained as described above. A higher ratio of D50 to F 2g of the FWTM of the peak is related to a larger microcrystalline size relative to the abrasive grain size. A smaller number of crystal plane defects also helps to increase the ratio of D50 to F 2g of the FWTM of the peak. It has been found that a higher ratio of D50 to F 2g of the FWTM of the peak can be related to an increase in the material removal rate. Therefore, the CeO2 abrasive grains have a ratio of D50 to the FWTM of the F 2g peak measured by Raman spectroscopy at a wavelength of 532 nm of at least 1.47. For example, the CeO2 abrasive grains have ratios of D50 to the FWTM of the F

[0104] The present invention also relates to the use of the electrochemomechanical polishing composition. The electrochemomechanical polishing composition of the present invention is used for electrochemomechanical polishing of a material containing a silicon material. As is known to those skilled in the art, electrochemomechanical polishing refers to the process of placing a material in an ECMP device and applying an electric current to bring the material into contact with a polishing pad and the electrochemomechanical polishing composition located therebetween. The polishing pad and the material move relative to each other to remove a portion of the material. Examples of silicon materials are SiC, crystalline silicon, silicon oxide, tetraethyl orthosilicate (TEOS), silicon nitride, and combinations thereof.

[0105] In some embodiments, the electrochemomechanical polishing composition of the present invention is used for electrochemomechanical polishing of a material containing SiC.

[0106] In addition to the above electrochemomechanical polishing composition and the use of the electrochemomechanical polishing composition, the embodiments of the present application also provide a method for electrochemomechanical polishing of a SiC material. Among them, the polishing liquid used in the method is the above electrochemomechanical polishing composition.

[0107] The steps of the method for electrochemomechanical polishing of a SiC material are as follows:

[0108] S1, Prepare the electrochemomechanical polishing composition and place it on a polishing pad in a polishing machine.

[0109] S2, Place a working electrode and a counter electrode in the above electrochemomechanical polishing composition so that the working electrode and the counter electrode are in contact with the electrochemomechanical polishing composition, and apply a current between the working electrode and the counter electrode to perform an electrochemical oxidation reaction on the surface of the SiC material to form a SiO2 oxide layer, where the working electrode is the SiC material adhered to the lower surface of the polishing head.

[0110] S3, Disperse the CeO2 abrasive grains in the electrochemomechanical polishing composition, bring the SiC material into contact with the polishing pad, and move the polishing head and the polishing pad to polish the SiO2 oxide layer.

[0111] The CeO2 abrasive grains can be prepared by any suitable method known to those skilled in the art to endow the abrasive grains with the above properties. In an embodiment, the CeO2 abrasive grains can be precipitated from cerium nitrate in an alkaline solution and prepared with a suitable size and morphology under suitable conditions. The abrasive grains can be centrifuged, washed, and dried. The particles can be further processed, such as by filtration, classification, crushing, grinding, milling, sonication, and combinations thereof, to deflocculate. The particles are dispersed and used to formulate the composition. Useful dispersion processes can be, for example, high-shear mixing, sonication, and other processes known to those skilled in the art.

[0112] The composition can be prepared by suitable techniques known to those skilled in the art. The CeO2 abrasive grains as described above and other components other than the CeO2 abrasive grains can be added to the aqueous carrier in any order in appropriate amounts to achieve the desired concentration. The CeO2 abrasive grains and other components can be mixed and stirred in the aqueous carrier. The pH value can be adjusted with the above pH regulator and pH buffer to obtain and maintain the desired pH. The CeO2 abrasive grains and other components can be added at any time before use (such as one month, one day, one hour or one minute) or during the ECMP process.

[0113] The composition can be provided as a single-part system, a two-part system or a multi-part system. For example, as a two-part system, the first part may include the CeO2 abrasive grains, and the second part may include one or more other components. The first part and the second part can be mixed at any time before the ECMP process (such as one month, one day, one hour or one minute) or during the ECMP process.

[0114] The composition can be provided as a concentrate and can be diluted with an appropriate amount of water before use. The concentration of each component in the composition can be any suitable one, such as 2 times, 3 times, 10 times or 25 times the concentration during use as described above. For example, the concentration of the CeO2 abrasive grains and other components contained in the concentrate is such that after dilution with an appropriate amount of water, the CeO2 abrasive grains and other components are present in the composition at the above concentration. If the composition is provided as a two-part system, for example, one or both parts can be provided as a concentrate. The two parts can be provided at different concentrations, for example, the concentration of the first part is three times and the concentration of the second part is five times. The two parts can be diluted in any order before mixing.

[0115] During polishing, the electrode is in contact with the composition and provides an electronic conductor for the composition to achieve the input or output of electrical energy, while the SiC material serves as the working electrode, which is the site where the electrochemical reaction occurs. The platinum electrode serves as the counter electrode and forms a circuit with the working electrode to ensure the smooth flow of current on the working electrode to guarantee that the reaction under study occurs on the working electrode. In addition to the platinum electrode, the counter electrode can also use a graphite rod electrode. The saturated calomel electrode serves as the reference electrode, and its potential is not affected by the change of the composition of the composition and has a constant value. In addition to the saturated calomel electrode, the reference electrode can also use an Ag / AgCl electrode, a mercury-mercuric oxide electrode, a mercurous sulfate electrode, etc.

[0116] The composition is a carrier for ion transport in the electrolytic cell and plays a role in conducting ions at the electrode. When an electric current is applied, the composition undergoes ion migration under the action of the current, thereby oxidizing the SiC material. It can oxidize the Si-C bonds on the surface of the SiC material into Si-O bonds to form a SiO2 oxide layer, reducing the Mohs hardness of the surface of the SiC material and achieving efficient oxidation of the surface of the SiC material.

[0117] In the step, the CeO2 abrasive grains can form Ce-O-Si bonds with the SiO2 molecules and weaken the Si-O-Si bonds between the SiO2 molecules. Therefore, under the action of the CeO2 abrasive grains, the Si-O-Si bonds are broken, and the CeO2 abrasive grains remove and polish the SiO2 molecular oxide layer in a whole-block manner to achieve polishing of the SiC material.

[0118] The following are specific examples of the composition designed according to the above content of the present disclosure. It should be clear that the following examples are only for illustrating the composition and polishing method disclosed above, and the specific implementation manners and parameters used are only one or several of the numerous parameters and methods that conform to the above. Those skilled in the art can use other parameters according to the content described in this specification and perform electrochemical mechanical polishing according to the above method without departing from the core spirit disclosed in the application.

[0119] In the following examples, the synthesis method of the cubic cerium dioxide abrasive grains of the present invention is as follows: Dissolve 0.03 mol of cerium(III) nitrate (Ce(NO3)3·6H2O) in 100 mL of deionized water, stir at room temperature until the solid is dissolved, and record it as liquid A. Dissolve 3.6 mol of sodium hydroxide (NaOH) in 500 mL of deionized water, stir until the solid is dissolved, and cool to room temperature, and record it as liquid B. Stir at room temperature and slowly add liquid A to liquid B, and continue stirring for 30 minutes. Transfer the mixed solution into a stainless steel hydrothermal autoclave with a Teflon lining, the synthesis temperature is 120 °C, the reaction time is 24 hours, and then naturally cool to room temperature. Centrifuge the cooled mixture to obtain a white solid. Wash the centrifuged white solid three times with water and ethanol respectively until the conductivity of the supernatant is less than 1 mS / cm. Dry the solid obtained from the last washing at 120 °C to obtain cerium dioxide abrasive grains with a cubic morphology.

[0120] The preparation method of the spherical cerium dioxide abrasive grains used in the embodiments of the present invention is as follows: Dissolve 0.03 mol of cerium(III) nitrate (Ce(NO3)3·6H2O) in 100 mL of deionized water, stir at room temperature until the solid is dissolved, and record it as liquid A. Dissolve 2.7 mol of polyvinylpyrrolidone (PVP) (counted by repeating unit) in 500 mL of deionized water, stir until the solid is dissolved, and cool to room temperature, and record it as liquid B. At room temperature, with stirring, slowly add liquid A to liquid B, and continuously stir for 60 minutes. Transfer the mixed solution into a stainless-steel hydrothermal autoclave with a Teflon lining, the synthesis temperature is 140 °C, the reaction time is 24 hours, and then naturally cool to room temperature. The cooled mixture is centrifuged to obtain a milky white solid. Wash the centrifuged white solid three times with water and ethanol respectively until the conductivity of the supernatant is less than 1 mS / cm. Drying the solid obtained from the last washing at 120 °C can obtain cerium dioxide abrasive grains with a spherical morphology.

[0121] In the following examples, 100 mm N-type (0.01 - 0.03 Ω·cm) 4H-SiC wafers were used. The Si surface of the SiC wafer was polished with a UNIPOL-1200S polishing machine (Shenyang Jingke Co., Ltd.), with a platinum electrode as the counter electrode, the SiC wafer as the working electrode, and a saturated calomel electrode as the reference electrode. Among them, the polishing head rotation speed was 60 rpm, the polishing pad rotation speed was 63 rpm, and the polishing pressure was 5 psi. ECMP estimates the material removal rate of SiC by measuring the weight loss during the polishing process. As described above, the particle sizes D01, D30, D50, D70, D99, and the z-average particle size were obtained by laser diffraction using Horiba LA-960. The zeta potential of the composition was measured with a Nano ZSE (Malvern Instruments).

[0122] Example 1

[0123] The electrochemically mechanical polishing composition consists of 2 wt.% cerium dioxide, 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). Adjust the pH value to 4 with potassium hydroxide. Table 1 lists the SiC material removal rates corresponding to adding different electrolytes in the electrochemically mechanical polishing composition.

[0124] Table 1

[0125]

[0126]

[0127] As can be seen from Table 1, compared with the electrochemical mechanical polishing composition A1, the electrochemical mechanical polishing compositions A2 to A14 added with electrolytes have a better SiC material removal rate, that is, adding electrolytes to the electrochemical mechanical polishing composition can increase the SiC material removal rate. In addition, compared with the electrochemical mechanical polishing compositions A2 to A4, the electrochemical mechanical polishing compositions A5 to A14 have a better SiC material removal rate, that is, adding organic electrolytes to the electrochemical mechanical polishing composition can increase the SiC material removal rate.

[0128] Example 2

[0129] The electrochemical mechanical polishing composition consists of 1 wt.% cerium dioxide, 0.1 M potassium isobutyrate, 0.04 wt% picolinic acid, 0.03 wt.% glycine, and 0.8 wt% polyethylene glycol (M.w. 600), and the pH is adjusted to 3.5 with isobutyric acid. The scratch coefficient is evaluated by calculating 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 length of the scratches is more than 75% of the SiC wafer diameter, the score is D. Table 2 lists the SiC removal rates corresponding to different cerium dioxides.

[0130] Table 2

[0131]

[0132] As can be seen from Table 2, compared with the electrochemical mechanical polishing compositions B1 and B4, the electrochemical mechanical polishing compositions B2 and B3 have a lower average particle size, a higher steepness factor and a lower slope factor, and exhibit a higher material removal rate and a lower scratch coefficient. Therefore, a low slope factor, a high steepness factor, and a low average particle size will produce fewer scratches and enhance the SiC material removal rate.

[0133] Example 3

[0134] The electrochemical mechanical polishing composition consists of 1.5 wt.% cerium dioxide, 0.05 wt% MOPS, 0.06 wt.% proline, 0.1 M potassium propionate, 1 wt% PEG (M.w. 800), 0.1 wt%. The pH value of the electrochemical mechanical polishing composition is adjusted to 3.5 with propionic acid. Table 3 lists the SiC material removal rates with the addition of oxidants in the electrochemical mechanical polishing composition.

[0135] Table 3

[0136]

[0137]

[0138] As can be seen from Table 3, compared with the electrochemical mechanical polishing composition C1, the removal rate of the SiC material in the electrochemical mechanical polishing compositions C2 to C8 added with an oxidant is lower. Therefore, adding an oxidant to the electrochemical mechanical polishing composition will reduce the removal rate of the SiC material.

[0139] 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 according to 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 without an oxidizing agent, which is used for polishing SiC materials, and is characterized in that, Comprising: A liquid carrier; A pH regulator; An organic electrolyte; And CeO2 abrasive grains, dispersed in the liquid carrier, wherein after power-on, an SiO2 molecular oxide layer is formed on the surface of the SiC material, and the CeO2 abrasive grains can form Ce-O-Si bonds with the SiO2 molecules and weaken the Si-O-Si bonds between the SiO2 molecules. Therefore, under the action of the CeO2 abrasive grains, the Si-O-Si bonds are broken, and the CeO2 abrasive grains remove and polish the SiO2 molecular oxide layer to achieve polishing of the SiC material.

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

3. The electrochemical mechanical polishing composition according to claim 1, wherein The CeO2 abrasive grains have a zeta potential of at least 10 mV at a pH value of 3.5 - 4.5 in the electrochemomechanical polishing composition.

4. The electrochemical mechanical polishing composition according to claim 1, wherein The electrochemomechanical polishing composition has a conductivity of at least 1 mS / cm at a pH value of 3.5 - 4.

5.

5. The electrochemical mechanical polishing composition according to claim 1, wherein The pH regulator includes an organic acid.

6. The electrochemical mechanical polishing composition according to claim 1, characterized in that, The organic electrolyte includes an organic monoacid salt.

7. The electrochemical mechanical polishing composition according to claim 6, characterized in that, The organic monoacid 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 claim 1, wherein The z-average particle size of the CeO2 abrasive grains does not exceed 90 nm.

9. The electrochemical mechanical polishing composition according to claim 1, characterized in that, The electrochemomechanical polishing composition does not contain inorganic acids.

10. Use of an electrochemically-mechanical polishing composition, characterized in that, Using the electrochemomechanical polishing composition according to any one of claims 1 to 9 for electrochemomechanical polishing of SiC materials.

11. A method for electrochemically mechanical polishing of SiC materials, characterized in that, Including the following steps: (1) Prepare the electrochemomechanical polishing composition according to any one of claims 1 to 9 and place it on a polishing pad; (2) Place the working electrode and the counter electrode in the electrochemomechanical polishing composition so that the working electrode and the counter electrode are in contact with the electrochemomechanical 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 SiC material to form an SiO2 oxide layer, wherein the working electrode is the SiC material adhered to the lower surface of the polishing head; (3) The CeO2 abrasive grains are dispersed in the electrochemomechanical polishing composition, bring the SiC material into contact with the polishing pad, and move the polishing head and the polishing pad to polish the SiO2 oxide layer.

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