WO2024203917A1 - Polishing composition - Google Patents

Abstract

The present invention provides a polishing composition with which friction on a polishing target can be reduced while maintaining a satisfactory polishing speed. The polishing composition contains inorganic particles, an oxidizing agent, and resin particles, the oxidizing agent contains a composite metal oxide, and the ratio (Nrp/Nip) of the number (Nip) of inorganic particles and the number (Nrp) of resin particles is 80 or higher.

Description

Polishing composition

The present invention relates to a polishing composition.
This application claims priority based on Japanese Patent Application No. 2023-056600, filed on March 30, 2023, the entire contents of which are incorporated herein by reference.

Abrasive compositions are used to polish the surfaces of materials such as metals, semimetals, nonmetals, and oxides thereof. For example, surfaces made of compound semiconductor materials such as silicon carbide, boron carbide, tungsten carbide, silicon nitride, titanium nitride, and gallium nitride are processed by polishing (lapping) by supplying diamond abrasive grains between the surface and a polishing table. However, lapping using diamond abrasive grains is prone to defects and distortions due to the generation and persistence of scratches and dents. Therefore, polishing (polishing) using a polishing pad and a polishing composition after lapping using diamond abrasive grains, or instead of lapping, is being considered. Patent Document 1 is an example of a document that discloses this type of prior art.

International Publication No. 2016/072370

From the standpoint of manufacturing efficiency and cost, it is desirable that the polishing speed when supplying a polishing liquid to polish an object be high enough for practical use. For example, when polishing an object made of a high-hardness material such as silicon carbide, it is desirable to further improve the polishing speed in order to improve the yield of the polished object.

When attempting to improve the polishing speed for objects made of high-hardness materials by adjusting the polishing conditions, possible methods include increasing the load applied to the object during polishing to increase the processing pressure, or increasing the rotation speed of the polishing platen of the polishing device. However, the above methods raise concerns that problems such as damage to the object to be polished may occur due to increased friction. If a polishing liquid that can effectively reduce the friction generated during polishing could be provided, problems would be less likely to occur even when polishing conditions are made more severe, such as high processing pressure and high-speed rotation of the platen, which would be beneficial for further improving the polishing speed.

The present invention was made in consideration of these circumstances, and aims to provide a polishing composition that can stably improve the polishing removal rate while suppressing the coefficient of friction during polishing.

The inventors focused on the effect of reducing frictional force due to rolling friction when a polishing composition contains inorganic particles and resin particles, and discovered that the relationship between the numbers of inorganic particles and resin particles contributes to a reduction in the friction coefficient without reducing the polishing removal rate.

The polishing composition provided in this specification contains inorganic particles, an oxidizing agent, and resin particles, the oxidizing agent contains a composite metal oxide, and the ratio (Nrp/Nip) of the number of inorganic particles (Nip) to the number of resin particles (Nrp) is 80 or more. With such a polishing composition, it is possible to stably improve the polishing removal rate while suppressing the coefficient of friction during polishing.

The following describes preferred embodiments of the present invention. Note that matters other than those specifically mentioned in this specification that are necessary for implementing the present invention can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field.

<Polishing Composition>
(Inorganic particles)
The polishing composition disclosed herein contains inorganic particles. The polishing composition containing inorganic particles exerts a mechanical polishing action, and thus a higher polishing removal rate can be achieved.

The material and properties of the inorganic particles are not particularly limited. For example, inorganic particles substantially composed of any of the following may be mentioned: oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate; etc. The inorganic particles may be used alone or in combination of two or more types. Among them, oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, zirconium oxide particles, manganese dioxide particles, and iron oxide particles are preferable because they can form a good surface. Among them, silica particles, alumina particles, zirconium oxide particles, chromium oxide particles, and iron oxide particles are more preferable, silica particles and alumina particles are even more preferable, and alumina particles are particularly preferable. In embodiments where alumina particles are used as inorganic particles, the technology disclosed herein can be applied to effectively improve the polishing removal rate.

In this specification, the phrase "consisting essentially of X" or "consisting essentially of X" in relation to the composition of an inorganic particle means that the proportion of X in the inorganic particle (the purity of X) is 90% or more by weight. The proportion of X in the inorganic particle is preferably 95% or more, more preferably 97% or more, even more preferably 98% or more, for example 99% or more.

The average primary particle diameter of the inorganic particles is not particularly limited. From the viewpoint of improving the polishing removal rate, the average primary particle diameter of the inorganic particles can be, for example, 5 nm or more, suitably 10 nm or more, preferably 20 nm or more, and may be 30 nm or more. From the viewpoint of further improving the polishing removal rate, in some embodiments, the average primary particle diameter of the inorganic particles may be 50 nm or more, 80 nm or more, 150 nm or more, 250 nm or more, or 350 nm or more. In addition, from the viewpoint of surface quality after polishing, the average primary particle diameter of the inorganic particles can be, for example, 5 μm or less, preferably 3 μm or less, more preferably 1 μm or less, 750 nm or less, or 500 nm or less. From the viewpoint of further improving the surface quality after polishing, in some embodiments, the average primary particle diameter of the inorganic particles may be 350 nm or less, 180 nm or less, 85 nm or less, or 50 nm or less.

In this specification, the average primary particle size refers to a particle size (BET particle size) calculated from the specific surface area (BET value) measured by the BET method by the formula: average primary particle size (nm) = 6000/(true density (g/ ^cm3 ) x BET value ( ^m2 /g)). The specific surface area can be measured, for example, using a surface area measuring device manufactured by Micromeritics, product name "Flow Sorb II 2300".

The average secondary particle diameter of the inorganic particles may be, for example, 10 nm or more, and from the viewpoint of easily increasing the polishing removal rate, it is preferably 50 nm or more, more preferably 100 nm or more, and may be 250 nm or more, or may be 400 nm or more. From the viewpoint of sufficiently securing the number per unit weight, it is appropriate to set the upper limit of the average secondary particle diameter of the inorganic particles to approximately 10 μm or less. Furthermore, from the viewpoint of surface quality after polishing, the above average secondary particle diameter is preferably 5 μm or less, more preferably 3 μm or less, for example 1 μm or less. From the viewpoint of further improving surface quality after polishing, in some embodiments, the average secondary particle diameter of the inorganic particles may be 600 nm or less, 300 nm or less, 170 nm or less, or 100 nm or less.

The average secondary particle diameter of inorganic particles can be measured as the volume average particle diameter (volume-based arithmetic mean diameter; Mv) for particles less than 500 nm by dynamic light scattering using, for example, a Nikkiso Co., Ltd. model "UPA-UT151." For particles 500 nm or larger, the volume average particle diameter can be measured by the pore electrical resistance method using a Beckman Coulter Co., Ltd. model "Multisizer 3."

When using alumina particles as inorganic particles, they can be appropriately selected from various known alumina particles. Examples of such known alumina particles include α-alumina and intermediate alumina. Intermediate alumina is a general term for alumina particles other than α-alumina, and specific examples include γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and χ-alumina. Alumina called fumed alumina (typically alumina fine particles produced when alumina salt is fired at high temperatures) based on classification by manufacturing method may also be used. Furthermore, alumina called colloidal alumina or alumina sol (e.g. alumina hydrate such as boehmite) is also included as an example of the above known alumina particles. From the viewpoint of processability, it is preferable to include α-alumina. The inorganic particles in the technology disclosed herein may include one type of such alumina particles alone or two or more types in combination.

When using alumina particles as inorganic particles, it is generally advantageous to have a higher proportion of alumina particles in the total inorganic particles used. For example, the proportion of alumina particles in the total inorganic particles is preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more, and may be substantially 100% by weight.

The particle size of the alumina particles is not particularly limited and may be selected so as to achieve the desired polishing effect. From the viewpoint of improving the polishing removal rate, etc., the average secondary particle diameter of the alumina particles is preferably 50 nm or more, more preferably 80 nm or more, and may be 150 nm or more, 250 nm or more, or 300 nm or more. There is no particular upper limit to the average secondary particle diameter of the alumina particles, but from the viewpoint of surface quality after polishing, it is appropriate to make it approximately 5 μm or less, and from the viewpoint of further improving surface quality after polishing, it is preferably 3 μm or less, more preferably 1 μm or less, and may be 750 nm or less, 500 nm or less, 400 nm or less, or 350 nm or less.

When alumina particles are used as the inorganic particles, the polishing composition disclosed herein may further contain inorganic particles made of a material other than the above-mentioned alumina (hereinafter also referred to as non-alumina particles) within a range that does not impair the effects of the present invention. Examples of such non-alumina particles include inorganic particles substantially composed of any of the following: oxide particles such as silica particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate.

The content of the non-alumina particles is suitably, for example, 30% by weight or less of the total weight of the inorganic particles contained in the polishing composition, preferably 20% by weight or less, and more preferably 10% by weight or less.

In another preferred embodiment of the technology disclosed herein, the polishing composition contains silica particles as inorganic particles. The silica particles can be appropriately selected from various known silica particles. Examples of such known silica particles include colloidal silica and dry process silica. Of these, the use of colloidal silica is preferred. With silica particles containing colloidal silica, good surface precision can be suitably achieved.

The shape (outer shape) of the silica particles may be spherical or non-spherical. For example, specific examples of non-spherical silica particles include a peanut shape (i.e., the shape of a peanut shell), a cocoon shape, a confetti shape, and a rugby ball shape. In the technology disclosed herein, the silica particles may be in the form of primary particles, or in the form of secondary particles in which multiple primary particles are aggregated. Furthermore, silica particles in the form of primary particles and silica particles in the form of secondary particles may be mixed. In a preferred embodiment, at least a portion of the silica particles are contained in the polishing composition in the form of secondary particles.

Silica particles having an average primary particle diameter of more than 5 nm can be preferably used. From the viewpoint of polishing efficiency, etc., the average primary particle diameter of the silica particles is preferably 15 nm or more, more preferably 20 nm or more, even more preferably 25 nm or more, and particularly preferably 30 nm or more. There is no particular upper limit to the average primary particle diameter of the silica particles, but it is appropriate to set it to approximately 120 nm or less, preferably 100 nm or less, and more preferably 85 nm or less. For example, from the viewpoint of achieving a higher level of both polishing efficiency and surface quality, silica particles having an average primary particle diameter of 12 nm to 80 nm are preferred, and silica particles having an average primary particle diameter of 15 nm to 75 nm are preferred.

The average secondary particle diameter of the silica particles is not particularly limited, but from the viewpoint of polishing efficiency, etc., it is preferably 20 nm or more, more preferably 50 nm or more, and even more preferably 70 nm or more. From the viewpoint of obtaining a higher quality surface, the average secondary particle diameter of the silica particles is appropriately 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less, even more preferably 130 nm or less, and particularly preferably 110 nm or less (e.g., 100 nm or less).

The true specific gravity (true density) of the silica particles is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. Increasing the true specific gravity of the silica particles tends to increase the physical polishing ability. There is no particular upper limit to the true specific gravity of the silica particles, but it is typically 2.3 or less, for example 2.2 or less, 2.0 or less, or 1.9 or less. The true specific gravity of the silica particles can be measured using a liquid substitution method using ethanol as the substitution liquid.

The shape (external shape) of the silica particles is preferably spherical. Although not particularly limited, the average value of the long axis/short axis ratio of the particles (average aspect ratio) is in principle 1.00 or more, and from the viewpoint of improving the polishing removal speed, it may be, for example, 1.05 or more, or 1.10 or more. Furthermore, the average aspect ratio of the particles is suitably 3.0 or less, and may be 2.0 or less. From the viewpoint of improving the smoothness of the polished surface and reducing scratches, the average aspect ratio of the particles is preferably 1.50 or less, and may be 1.30 or less, or may be 1.20 or less.

The shape (outer shape) and average aspect ratio of particles can be determined, for example, by observation with an electron microscope. A specific procedure for determining the average aspect ratio is to extract the shapes of a specified number of particles (e.g., 200 particles) using a scanning electron microscope (SEM). The smallest rectangle that circumscribes the shape of each extracted particle is then drawn. Then, for the rectangle drawn for each particle shape, the long side length (long axis value) is divided by the short side length (short axis value) to calculate the long axis/short axis ratio (aspect ratio). The average aspect ratio can be found by arithmetically averaging the aspect ratios of the specified number of particles.

In an embodiment in which the polishing composition contains silica particles, the polishing composition may further contain inorganic particles made of a material other than silica (hereinafter also referred to as non-silica particles). Examples of particles constituting such non-silica particles include oxide particles such as alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese oxide particles, zinc oxide particles, and iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate; and the like.

The content of the non-silica particles is suitably, for example, 30% by weight or less of the total weight of the inorganic particles contained in the polishing composition, preferably 20% by weight or less, and more preferably 10% by weight or less.

The content of inorganic particles in the polishing composition disclosed herein is suitably less than 50 wt%, advantageously less than 40 wt%, preferably less than 30 wt%, more preferably less than 25 wt%, and may be less than 10 wt%, 9 wt% or less, 8 wt% or less, 7 wt% or less, or 6 wt% or less, from the viewpoint of surface quality after polishing, etc. In some embodiments, the content of inorganic particles in the polishing composition may be 0.5 wt% or less or less than 0.5 wt%, 0.1 wt% or less or less than 0.1 wt%, 0.05 wt% or less or less than 0.05 wt%, or 0.04 wt% or less or less than 0.04 wt%.

The lower limit of the content of inorganic particles in the polishing composition disclosed herein is not particularly limited, and may be, for example, 0.000001 wt % or more (i.e., 0.01 ppm or more). From the viewpoint of enhancing the use effect of the inorganic particles, in some embodiments, the content of inorganic particles in the polishing composition may be 0.00001 wt % or more, 0.0001 wt % or more, 0.001 wt % or more, 0.002 wt % or more, or 0.005 wt % or more. In some embodiments, the content of inorganic particles in the polishing composition may be 0.01 wt % or more, 0.02 wt % or more, 0.03 wt % or more, more than 0.1 wt %, more than 0.3 wt %, 0.5 wt % or more, or 0.8 wt % or more. When the polishing composition disclosed herein contains multiple types of inorganic particles, the content of inorganic particles in the polishing composition refers to the total content of the multiple types of inorganic particles.

The polishing composition disclosed herein is preferably one that is substantially free of diamond particles. Diamond particles have a high hardness, which can be a limiting factor in improving smoothness. In addition, diamond particles are generally expensive, and therefore cannot be said to be an advantageous material in terms of cost-effectiveness, and from a practical standpoint, the reliance on expensive materials such as diamond particles may be low. Here, "particles that are substantially free of diamond particles" means that the proportion of diamond particles among all particles contained in the polishing composition is 1% by weight or less, more preferably 0.5% by weight or less, typically 0.1% by weight or less, and includes the case where the proportion of diamond particles is 0% by weight. In such an embodiment, the effect of the application of the present invention can be preferably exhibited.

(Resin particles)
The polishing composition disclosed herein contains resin particles. The polishing composition containing resin particles exhibits a frictional force reducing effect due to rolling friction, so that the friction coefficient can be reduced without decreasing the polishing removal rate. In this specification, "resin particles" are particles containing an organic substance. In some preferred embodiments, the resin particles are particles containing an organic substance as a main component. Here, in this specification, "main component" refers to a component that accounts for more than 50% by weight of the total. The resin particles may have a solubility in water at 25°C of 5 g/100 mL or less.

The resin particles are preferably composed of a polymer containing carbon as a main component. The material constituting the resin particles may be a thermoplastic resin or a thermosetting resin. Examples of the thermoplastic resin include general-purpose resins; engineering resins; and the like. Examples of the general-purpose resins include polyolefin resins such as polyethylene, polypropylene, polybutene, polyisobutylene, and polymethylpentene; polyethylene-vinyl acetate resins; acrylic resins such as polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polymethacrylic acid, and polyacrylic acid; styrene resins; styrene-acrylic resins; saturated polyester resins such as polyethylene terephthalate (PET); and vinyl chloride resins. The engineering resins may be general-purpose engineering resins or super engineering resins. Examples of the general-purpose engineering resins include polyamide resins such as nylon and aramid; polyacetal resins; polycarbonate resins; and the like. Examples of the super engineering resins include fluororesins such as polytetrafluoroethylene (PTFE); polysulfone resins; polyethersulfone (PES) resins; thermoplastic polyimide resins; and the like. Examples of thermosetting resins include phenol resins, melamine resins, amino resins, epoxy resins, urea resins, unsaturated polyester resins, polyurethane resins, acrylic-urethane resins, thermosetting polyimide resins, benzoguanamine resins, silicone resins, and the like. As the resin particles, resin particles substantially composed of any of the above resins can be used. The resin particles may be used alone or in combination of two or more. Among them, polyolefin resins, acrylic resins, styrene-acrylic resins, vinyl chloride resins, melamine resins, polyurethane resins, and acrylic-urethane resins are more preferred, styrene-acrylic resins and acrylic resins are even more preferred, and acrylic resins are particularly preferred. In an embodiment in which acrylic resins are used as resin particles, the effect of improving the polishing removal rate can be suitably exhibited by applying the technology disclosed herein.

In this specification, the phrase "consists essentially of X" or "consists essentially of X" in relation to the composition of a resin particle means that the proportion of X in the resin particle (the purity of X) is 90% or more by weight. The proportion of X in the resin particle is preferably 95% or more, more preferably 97% or more, even more preferably 98% or more, for example 99% or more.

The resin particles may be charged or uncharged. Anionic, cationic, nonionic, or amphoteric particles may be used as the resin particles. At least one functional group selected from anionic, cationic, amphoteric, and nonionic functional groups may be introduced to the surface of the resin particles. Examples of anionic functional groups include carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type, and examples of cationic functional groups include amine salt type and quaternary ammonium salt type. Examples of amphoteric functional groups include alkanolamide type, carboxybetaine type, and glycine type, and examples of nonionic functional groups include ether type and ester type.

In some embodiments, the material constituting the resin particles is an anionic acrylic resin or a cationic acrylic resin. In other embodiments, the material constituting the resin particles is an anionic styrene-acrylic resin.

The resin constituting the resin particles may be either a resin that is a crosslinked product obtained by mixing and reacting a base agent with a curing agent (crosslinked resin) or a non-crosslinked resin (non-crosslinked resin). The base agent is the above-mentioned resin (e.g., acrylic resin). The curing agent is not particularly limited, but may be, for example, an epoxy compound or an isocyanate compound. In some embodiments, the material constituting the resin particles is a crosslinked acrylic resin or a non-crosslinked acrylic resin. In other embodiments, the material constituting the resin particles is a crosslinked styrene-acrylic resin or a non-crosslinked styrene-acrylic resin.

Resin particles prepared by a known method may be used, or those having particle size, shape, properties, etc. suitable as abrasives for polishing a substrate or other object to be polished (typically a silicon wafer) may be selected from among commercially available products available from various manufacturers. For example, acrylic resin particles may be selected from commercially available products available from Nippon Paint, DIC, Aica Kogyo, etc. Styrene resin particles may be selected from commercially available products available from Nippon Paint, etc. Styrene-acrylic resin particles may be selected from commercially available products available from Nippon Shokubai, Nippon Paint, etc. Nylon resin particles may be selected from commercially available products available from Toray, etc. Epoxy resin particles may be selected from commercially available products available from Toray, etc. Saturated polyester resin particles may be selected from commercially available products available from Unitika, Sekisui Chemical, etc. Polyurethane resin particles may be selected from commercially available products available from Aica Kogyo, etc. The phenolic resin particles can be selected from commercially available products available from Air Water, Sumitomo Bakelite, etc. The benzoguanamine resin particles can be selected from commercially available products available from Nippon Shokubai, etc. The PES resin particles can be selected from commercially available products available from Japan Material Technology Institute, etc. The PTFE resin particles can be selected from commercially available products available from Techno Chemical, etc. Such resin particles can be used alone or in combination of two or more types.

The average particle diameter of the resin particles may be, for example, 1 nm or more, and from the viewpoint of easily increasing the polishing removal rate, it is preferably 5 nm or more, more preferably 10 nm or more, may be 15 nm or more, or may be 20 nm or more. From the viewpoint of ensuring a sufficient number per unit weight, it is appropriate that the upper limit of the average particle diameter of the resin particles is approximately 10 μm or less. Furthermore, from the viewpoint of improving the polishing removal rate, the above average particle diameter is preferably 5 μm or less, more preferably 3 μm or less, for example, 2 μm or less, 1.5 μm or less, or 1 μm or less. From the viewpoint of further improving the polishing removal rate, in some embodiments, the average particle diameter of the resin particles may be 60 nm or less, 50 nm or less, 40 nm or less, or 30 nm or less.

The method for measuring the average particle diameter of the resin particles is not particularly limited, and a known method appropriate for the particle diameter can be used. For example, the median diameter in the particle size distribution measured by a laser diffraction scattering method can be used as the average particle diameter of the resin particles. In addition, when using commercially available resin particles, the manufacturer's nominal value (catalog value) can be used as the average particle diameter of the resin particles.

The content of resin particles in the polishing composition disclosed herein is suitably less than 10% by weight, advantageously less than 6% by weight, preferably less than 3% by weight, more preferably less than 2% by weight, and may be less than 1.5% by weight, 1.3% by weight or less, 1.2% by weight or less, 1.1% by weight or less, or 1.0% by weight or less. In some embodiments, the content of resin particles in the polishing composition may be 0.5% by weight or less or less than 0.5% by weight, 0.1% by weight or less or less than 0.1% by weight, 0.05% by weight or less or less than 0.05% by weight, or 0.04% by weight or less or less than 0.04% by weight. The lower limit of the content of resin particles is not particularly limited, and may be, for example, 0.000001% by weight or more (i.e., 0.01 ppm or more). From the viewpoint of enhancing the effect of using the resin particles, in some embodiments, the content of the resin particles in the polishing composition may be 0.00001% by weight or more, 0.0001% by weight or more, 0.001% by weight or more, 0.002% by weight or more, or 0.005% by weight or more. In some embodiments, the content of the resin particles in the polishing composition may be 0.01% by weight or more, 0.02% by weight or more, 0.03% by weight or more, more than 0.1% by weight, more than 0.3% by weight, 0.5% by weight or more, or 0.8% by weight or more. When the polishing composition disclosed herein contains multiple types of resin particles, the content of the resin particles in the polishing composition refers to the total content of the multiple types of resin particles.

In the polishing composition disclosed herein, the number concentration of inorganic particles and the number concentration of resin particles satisfy a predetermined relationship. That is, in the polishing composition, the ratio of the number of resin particles (number concentration) Nrp [pieces/L] to the number of inorganic particles (number concentration) Nip [pieces/L], i.e., Nrp/Nip, is 80 or more. For example, it can be approximately 90 or more, and it is appropriate to set it to 100 or more. As Nrp/Nip increases, the friction coefficient tends to decrease. In some preferred embodiments, Nrp/Nip may be 120 or more, 140 or more, or even 160 or more.

In the polishing composition disclosed herein, the upper limit of Nrp/Nip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, about 500 × 10 ⁴ or less, may be 400 × 10 ⁴ or less, may be 300 × 10 ⁴ or less, or may be 200 × 10 ⁴ or less. In some embodiments, Nrp/Nip may be 100,000 or less, may be 50,000 or less, or may be 40,000 or less.

In the above "Nrp/Nip," "Nrp" represents the numerical value when the number concentration of resin particles in the polishing composition is expressed in units of "pieces/L," and "Nip" represents the numerical value when the number concentration of inorganic particles in the polishing composition is expressed in units of "pieces/L," and both Nrp and Nip are dimensionless numbers.

The number concentration of the inorganic particles is calculated by the formula: number concentration of inorganic particles (pieces/L) = concentration of inorganic particles in the polishing composition (g/L) / weight per inorganic particle (g/piece). Here, the weight per inorganic particle is calculated by the formula: weight per inorganic particle (g/piece) = (4/3) x π x (radius of inorganic particle (m)) ³ x density of inorganic particle (g/m ³ ). The number concentration of the resin particles can be calculated in the same manner. The radius of the inorganic particles is 1/2 the value of the average secondary particle diameter of the inorganic particles. The radius of the resin particles is 1/2 the value of the average particle diameter of the resin particles.

In the polishing composition disclosed herein, the relationship between the content of inorganic particles and the content of resin particles is not particularly limited as long as the relationship of the number concentrations described above is satisfied. The ratio of the content of resin particles Wrp [wt %] to the content of inorganic particles Wip [wt %], i.e., Wrp/Wip, can be, for example, approximately 0.001 or more, and is preferably 0.0025 or more, and may be 0.003 or more, 0.004 or more, or 0.005 or more. In some preferred embodiments, Wrp/Wip may be 0.02 or more, or 0.03 or more.

In the polishing composition disclosed herein, the upper limit of Wrp/Wip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, approximately 5000 or less, and may be 1500 or less, 1000 or less, 800 or less, 400 or less, 250 or less, 100 or less, 80 or less, or 40 or less. In some embodiments, Wrp/Wip may be 30 or less, 20 or less, 10 or less, 5 or less, 1 or less, 0.5 or less, 0.1 or less, or 0.05 or less.

In the above "Wrp/Wip," "Wrp" is the numerical value when the resin particle content in the polishing composition is expressed in units of "weight %," and "Wip" is the numerical value when the inorganic particle content in the polishing composition is expressed in units of "weight %." Both Wrp and Wip are dimensionless numbers.

(Oxidizing Agent)
The polishing composition disclosed herein contains an oxidizing agent. The oxidizing agent is effective in reducing the hardness of the material to be polished (e.g., a non-oxide material with high hardness such as silicon carbide) and weakening the material. Therefore, the oxidizing agent can exert the effect of improving the polishing removal rate in polishing the material to be polished. In this specification, the oxidizing agent does not include the metal salt described later.

The polishing composition disclosed herein is characterized by containing a complex metal oxide as an oxidizing agent. The structure containing a complex metal oxide as an oxidizing agent makes it easy to improve the polishing performance. The complex metal oxide can be used alone or in combination of two or more. Examples of the complex metal oxide include ferric acids, permanganic acids, chromic acids, vanadic acids, ruthenic acids, molybdic acids, perrhenic acids, and tungstic acids. Among them, ferric acids, permanganic acids, chromic acids, vanadic acids, molybdic acids, and tungstic acids are more preferred, and permanganic acids and vanadic acids are even more preferred. In addition, the complex metal oxide may include a complex transition metal oxide that is a salt of a cation selected from alkali metal ions and an anion selected from transition metal oxo acid ions. Specific examples of the transition metal oxo acid ion in the composite transition metal oxide include permanganate ion, ferrate ion, chromate ion, dichromate ion, vanadate ion, ruthenate ion, molybdate ion, rhenate ion, tungstate ion, etc. Among these, oxo acids of the fourth period transition metal elements in the periodic table are more preferred. Suitable examples of the fourth period transition metal elements in the periodic table include Fe, Mn, Cr, V, and Ti. Among these, Fe, Mn, Cr, and V are more preferred, and Mn and V are even more preferred. The alkali metal ion in the composite transition metal oxide is preferably Na ⁺ or K ⁺ . In some embodiments, sodium permanganate, potassium permanganate, and sodium metavanadate can be preferably used as the oxidizing agent.

The content of the oxidizing agent in the polishing composition disclosed herein is not particularly limited and may be appropriately set depending on the purpose and manner of use of the polishing composition. In some embodiments, from the viewpoint of improving the polishing removal rate, it is appropriate that the content of the oxidizing agent is approximately 0.5% by weight or more. From the viewpoint of improving the polishing removal rate, the content of the oxidizing agent is preferably 1% by weight or more, more preferably 1.4% by weight or more. In some embodiments, the content of the oxidizing agent may be 2.7% by weight or more, 4% by weight or more, 6% by weight or more, 6.5% by weight or more, 8% by weight or more, 9% by weight or more, 10% by weight or more, 15% by weight or more, 20% by weight or more, or 22% by weight or more. In some embodiments, the content of the oxidizing agent in the polishing composition is suitably about 45% by weight or less, preferably 40% by weight or less, more preferably 35% by weight or less, even more preferably 30% by weight or less, may be 25% by weight or less, may be 20% by weight or less, may be 15% by weight or less, or may be 10% by weight or less.

The polishing composition disclosed herein may or may not further contain an oxidizing agent other than the composite metal oxide (hereinafter also referred to as "other oxidizing agent"). Specific examples of compounds that can be selected as the other oxidizing agent include peroxides such as hydrogen peroxide; periodic acids such as periodic acid and its salts, sodium periodate and potassium periodate; iodic acids such as iodic acid and its salts, ammonium iodate; bromic acids such as bromic acid and its salts, potassium bromate; persulfuric acids such as peroxomonosulfuric acid and peroxodisulfuric acid, and persulfuric acids such as ammonium persulfate and potassium persulfate; chloric acids and perchloric acids such as chloric acid and its salts, perchloric acid and its salts, potassium perchlorate; osmic acids such as perosmic acid and osmic acid; selenic acids such as perselenic acid and selenic acid; and ammonium cerium nitrate. As the other oxidizing agent, one or more of such compounds can be used in combination. In some embodiments, from the viewpoint of the performance stability of the polishing composition (e.g., prevention of deterioration due to long-term storage), etc., it is preferable that the other oxidizing agent is an inorganic compound.

When the compound used as the oxidizing agent is a salt (e.g., permanganate), the compound may be present in the polishing composition in an ionic state.

In the polishing composition disclosed herein, the relationship between the content of the oxidizing agent and the content of the inorganic particles is not particularly limited, and can be appropriately set so as to achieve the desired effect depending on the purpose and mode of use. The ratio of the content of the oxidizing agent Wx [wt %] to the content of the inorganic particles Wip [wt %], i.e., Wx/Wip, can be, for example, approximately 0.001 or more, suitably 0.002 or more, may be 0.005 or more, may be 0.01 or more, may be 0.02 or more, may be 0.1 or more, is advantageously 0.15 or more, is preferably 0.2 or more, and is more preferably 0.3 or more. The larger Wx/Wip is, the greater the contribution of chemical polishing to the contribution of mechanical polishing tends to be. In some embodiments, Wx/Wip may be 0.5 or more, or may be 0.6 or more.

In the polishing composition disclosed herein, the upper limit of Wx/Wip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, approximately 20 or less, or it can be 15 or less, 10 or less, 5 or less, 3 or less, 2 or less, 1 or less, 0.8 or less, or 0.7 or less.

In the above "Wx/Wip," "Wx" is the numerical value of the oxidizing agent content in the polishing composition expressed in units of "weight %," and "Wip" is the numerical value of the inorganic particle content in the polishing composition expressed in units of "weight %." Both Wx and Wip are dimensionless numbers.

In the polishing composition disclosed herein, the relationship between the content of the oxidizing agent and the content of the resin particles is not particularly limited, and can be appropriately set so as to achieve the desired effect depending on the purpose and mode of use. The ratio of the content of the oxidizing agent Wx [wt %] to the content of the resin particles Wrp [wt %], i.e., Wx/Wrp, can be, for example, approximately 0.1 or more, and is preferably 0.25 or more, and may be 0.5 or more, 1 or more, 2 or more, 5 or more, or 10 or more. As Wx/Wrp increases, the contribution of chemical polishing to the contribution of mechanical polishing tends to be greater. In some embodiments, Wx/Wrp may be 50 or more, 60 or more, or even 65 or more, 100 or more, 150 or more, or 200 or more.

In the polishing composition disclosed herein, the upper limit of Wx/Wrp is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, approximately 5000 or less, and may be 1500 or less, 1000 or less, 800 or less, 400 or less, 300 or less, 200 or less, 100 or less, or 75 or less. In some embodiments, Wx/Wrp may be 50 or less, 40 or less, or 30 or less.

In the above "Wx/Wrp," "Wx" is the numerical value when the content of the oxidizing agent in the polishing composition is expressed in units of "weight %," and "Wrp" is the numerical value when the content of the resin particles in the polishing composition is expressed in units of "weight %," and both Wx and Wrp are dimensionless numbers.

(Metal Salts)
The polishing composition disclosed herein may contain a metal salt. By using the metal salt, the polishing removal rate is more likely to be improved. In addition, by using the metal salt, the performance deterioration of the polishing composition (e.g., the decrease in the polishing removal rate, etc.) is more likely to be suppressed. The metal salt can be selected from one or more of the metal salts A, B, and C described below.

(Metal Salt A)
In some preferred embodiments, the polishing composition comprises metal salt A selected from alkaline earth metal salts. As the metal salt A, one kind of alkaline earth metal salt may be used alone, or two or more kinds of alkaline earth metal salts may be used in combination. By using the metal salt A, the polishing removal rate can be improved. As an element belonging to alkaline earth metals, the metal salt A preferably comprises one or more of Mg, Ca, Sr, and Ba. Among them, any of Ca and Sr is preferred, and Ca is more preferred.

The type of salt in the metal salt A is not particularly limited, and may be an inorganic acid salt or an organic acid salt. Examples of inorganic acid salts include salts of hydrohalic acids such as hydrochloric acid, hydrobromic acid, and hydrofluoric acid, and salts of nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid, and phosphoric acid. Examples of organic acid salts include salts of carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycine acid, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid; organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid, and toluenephosphonic acid; and organic phosphoric acids such as ethylphosphoric acid. Among these, salts of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferred, and salts of hydrochloric acid and nitric acid are more preferred. The technology disclosed herein can be preferably implemented, for example, in an embodiment in which a nitrate or chloride of an alkaline earth metal is used as the metal salt A.

Specific examples of alkaline earth metal salts that can be used as metal salt A include chlorides such as magnesium chloride, calcium chloride, strontium chloride, and barium chloride; bromides such as magnesium bromide, calcium bromide, strontium bromide, and barium bromide; fluorides such as magnesium fluoride, calcium fluoride, strontium fluoride, and barium fluoride; nitrates such as magnesium nitrate, calcium nitrate, strontium nitrate, and barium nitrate; sulfates such as magnesium sulfate, calcium sulfate, strontium sulfate, and barium sulfate; carbonates such as magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate; carboxylates such as magnesium acetate, calcium acetate, strontium acetate, barium acetate, magnesium benzoate, calcium benzoate, barium benzoate, magnesium citrate, calcium citrate, strontium citrate, and barium citrate; etc.

The metal salt A is preferably a water-soluble salt. By using a water-soluble metal salt A, a good surface with few defects such as scratches can be efficiently formed.
In addition, metal salt A is preferably a compound that is not oxidized by oxidizing agent.From this viewpoint, by appropriately selecting oxidizing agent and metal salt A, it is possible to prevent the deactivation of the oxidizing agent caused by the oxidation of metal salt A by the oxidizing agent, and suppress the deterioration of the performance of polishing composition over time (for example, the decrease in polishing removal rate, etc.).From this viewpoint, calcium nitrate can be mentioned as a preferred metal salt A.

When the polishing composition contains metal salt A, the concentration (content) of metal salt A in the polishing composition is not particularly limited and can be appropriately set so as to achieve the desired effect depending on the purpose and manner of use of the polishing composition. The concentration of metal salt A may be, for example, approximately 1000 mM or less (i.e., 1 mol/L or less), may be 500 mM or less, or may be 300 mM or less. In some embodiments, the concentration of metal salt A is suitably 200 mM or less, preferably 100 mM or less, more preferably 50 mM or less, may be 30 mM or less, may be 20 mM or less, or may be 10 mM or less. The lower limit of the concentration of metal salt A may be, for example, 0.1 mM or more, and from the viewpoint of appropriately exerting the effect of using metal salt A, it is preferably 0.5 mM or more, more preferably 1 mM or more, and may be 2.5 mM or more, 5 mM or more, 10 mM or more, 20 mM or more, or 30 mM or more.

In the polishing composition containing metal salt A, the relationship between the concentration of metal salt A and the content of inorganic particles is not particularly limited, and can be appropriately set so as to achieve the desired effect according to the purpose of use and the mode of use. The ratio of the concentration CA of metal salt A (if a plurality of metal salts A are contained, the total concentration thereof) [mM] to the content Wip of inorganic particles (if a plurality of inorganic particles are contained, the total content thereof) [wt %], i.e., CA/Wip, can be, for example, 0.05 or more, and is suitably 0.1 or more, may be 0.2 or more, preferably 1 or more, more preferably 3 or more, may be 5 or more, or may be 10 or more. When CA/Wip is larger, the contribution of chemical polishing to the contribution of mechanical polishing tends to be larger. In some embodiments, CA/Wip may be 12 or more, may be 15 or more, or may be 18 or more. The upper limit of CA/Wip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, about 20,000 or less, may be 10,000 or less, may be 5,000 or less, may be 2,500 or less, or may be 1,000 or less. In some embodiments, CA/Wip may be 100 or less, may be 50 or less, may be 40 or less, or may be 30 or less.
In the above "CA/Wip,""CA" represents the numerical value when the concentration of metal salt A in the polishing composition is expressed in units of "mM," and "Wip" represents the numerical value when the content of inorganic particles in the polishing composition is expressed in units of "weight %," and both Wip and CA are dimensionless numbers.

(Metal Salt B)
In some preferred embodiments, the polishing composition contains a metal salt B selected from salts of a cation containing a metal belonging to Groups 3 to 16 of the periodic table and an anion. As the metal salt B, one metal salt selected from salts of a cation containing a metal belonging to Groups 3 to 16 of the periodic table and an anion can be used alone or in combination of two or more metal salts. By using the metal salt B, the polishing removal rate can be improved.

The cation of metal salt B may be a cation containing a transition metal, i.e., a metal belonging to groups 3 to 12 of the periodic table, or a cation containing a poor metal, i.e., a metal belonging to groups 13 to 16. The transition metal is preferably one belonging to groups 4 to 11 of the periodic table, and is also suitable for those belonging to periods 4 to 6 of the periodic table, with those belonging to periods 4 to 5 being preferred, and those belonging to period 4 being more preferred. The poor metal is preferably one belonging to groups 13 to 15 of the periodic table, and more preferably one belonging to groups 13 to 14, and is also preferably one belonging to periods 3 to 5 of the periodic table, and more preferably one belonging to periods 3 to 4, with the poor metal belonging to period 3 being particularly preferred, i.e., aluminum.

In some embodiments, metal salt B is preferably a salt of an anion and a cation containing a metal whose hydrated metal ion has a pKa of less than about 7. Metal salt B, which is a salt of such a cation and an anion, generates a hydrated metal cation in water, and the hydrated metal cation acts as a pH buffer because the proton on the coordinated water is in an equilibrium between attachment and detachment, and thus is easy to suppress the deterioration of the performance of the polishing composition over time. From this viewpoint, metal salt B can preferably be a salt of a metal cation whose hydrated metal ion has a pKa of less than 7.0 or 6.0 or less, for example, and an anion. Examples of metal cations having a pKa of 6.0 or less include, but are not limited to, Al ³⁺ (pKa of hydrated metal ion: 5.0), Cr ³⁺ (pKa of hydrated metal ion: 4.2), Fe ³⁺ (pKa of hydrated metal ion: 2.2), ZrO ²⁺ (pKa of hydrated metal ion: -0.3), Ga ³⁺ (pKa of hydrated metal ion: 2.6), and In ³⁺ (pKa of hydrated metal ion: 4.0).

The type of salt in the metal salt B is not particularly limited, and may be an inorganic acid salt or an organic acid salt. Examples of inorganic acid salts include salts of hydrohalic acids such as hydrochloric acid, hydrobromic acid, and hydrofluoric acid, and salts of nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid, and phosphoric acid. Examples of organic acid salts include salts of carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycine acid, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid; organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid, and toluenephosphonic acid; and organic phosphoric acids such as ethylphosphoric acid. Among them, salts of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferred, and salts of hydrochloric acid, nitric acid, and sulfuric acid are more preferred. The technology disclosed herein can be preferably carried out in an embodiment using, for example, a salt of any one of the cations Al ³⁺ , Cr ³⁺ , Fe ³⁺ , ZrO ²⁺ , Ga ³⁺ , and In ³⁺ with a nitrate ion (NO ³⁻ ) or a chloride ion (Cl ⁻ ) as metal salt B.

The metal salt B is preferably a water-soluble salt. By using a water-soluble metal salt B, a good surface with few defects such as scratches can be efficiently formed.
In addition, metal salt B is preferably a compound that is not oxidized by oxidizing agent.From this viewpoint, by appropriately selecting oxidizing agent and metal salt B, it is possible to prevent the deactivation of the oxidizing agent caused by the oxidation of metal salt B by the oxidizing agent, and to suppress the deterioration of the performance of polishing composition over time (for example, the decrease in polishing removal rate, etc.).From this viewpoint, preferred examples of metal salt B include aluminum nitrate, aluminum chloride, etc.

When the polishing composition contains metal salt B, the concentration (content) of metal salt B in the polishing composition is not particularly limited and can be appropriately set so as to achieve the desired effect depending on the purpose and mode of use of the polishing composition. The concentration of metal salt B may be, for example, approximately 1000 mM or less (i.e., 1 mol/L or less), may be 500 mM or less, or may be 300 mM or less. In some embodiments, the concentration of metal salt B is appropriately 200 mM or less, preferably 100 mM or less, more preferably 50 mM or less, may be 40 mM or less, may be 35 mM or less, or may be 32 mM or less. The lower limit of the concentration of metal salt B may be, for example, 0.1 mM or more, and from the viewpoint of appropriately exerting the effect of use of metal salt B, it is advantageous to set it to 1 mM or more, preferably 5 mM or more, more preferably 10 mM or more (e.g., 15 mM or more), may be 20 mM or more, or may be 25 mM or more.

In the polishing composition containing metal salt B, the relationship between the concentration of metal salt B and the content of inorganic particles is not particularly limited, and can be appropriately set so as to achieve the desired effect according to the purpose of use and the mode of use. The ratio of the concentration CB of metal salt B (the total concentration of multiple metal salts B) [mM] to the content Wip of inorganic particles (the total content of multiple inorganic particles) [wt %], i.e., CB/Wip, can be, for example, 0.05 or more, and is suitably 0.1 or more, may be 0.2 or more, preferably 1 or more, more preferably 3 or more, may be 5 or more, or may be 10 or more. When CB/Wip is larger, the contribution of chemical polishing to the contribution of mechanical polishing tends to be larger. In some embodiments, CB/Wip may be 20 or more, 50 or more, 100 or more, or 300 or more. The upper limit of CB/Wip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it can be, for example, about 10,000 or less, may be 5,000 or less, or may be 2,500 or less. In some embodiments, CB/Wip may be 1,000 or less, 800 or less, or 600 or less.
In the above "CB/Wip,""CB" represents the numerical value when the concentration of metal salt B in the polishing composition is expressed in units of "mM," and "Wip" represents the numerical value when the content of inorganic particles in the polishing composition is expressed in units of "weight %," and both CB and Wip are dimensionless numbers.

(Metal Salt C)
In some preferred embodiments, the polishing composition contains a metal salt C selected from salts of a cation containing a transition metal, i.e., a metal belonging to Groups 3 to 12 of the periodic table, and an anion. The metal salt C can be used alone or in combination of two or more. By using the metal salt C in the polishing composition containing an oxidizing agent, it is possible to suppress deterioration of the performance of the polishing composition (e.g., a decrease in the polishing removal rate, etc.) caused by pH fluctuation of the polishing composition during polishing of an object to be polished.

The above transition metals are preferably those belonging to groups 4 to 11 of the periodic table, and more preferably those belonging to periods 4 to 6 of the periodic table, more preferably those belonging to periods 4 to 5, and even more preferably those belonging to period 4.

In some embodiments, the metal salt C is preferably a salt of an anion and a cation containing a metal whose hydrated metal ion has a pKa value of less than about 7. The metal salt C, which is a salt of such a cation and an anion, forms a hydrated metal cation in water, and the hydrated metal cation acts as a pH buffer because the proton on the coordinated water is in an attachment/detachment equilibrium, and is easy to suppress the performance deterioration of the polishing composition over time. From this viewpoint, the metal salt C can preferably be a salt of an anion and a cation containing a metal whose hydrated metal ion has a pKa value of less than 7 or less than 6. Examples of metal cations having a pKa of 6 or less for their hydrated metal ions include, but are not limited to, Cr ³⁺ (pKa of their hydrated metal ions is 4.2), Fe ³⁺ (pKa of their hydrated metal ions is 2.2), Hf ⁴⁺ (pKa of their hydrated metal ions is 0.2), Zr ⁴⁺ (pKa of their hydrated metal ions is -0.3), Ti ⁴⁺ (pKa of their hydrated metal ions is -4.0), etc.

Examples of cations constituting the metal salt C include, but are not limited to, single-atom transition metal cations such as Cr3 ⁺ , Fe3 ⁺ , ^Hf4 +, ^Zr4 +, Ti4 ⁺ , etc.; oxytransition metal cations such as ZrO2 ⁺ , ZrO ⁺ , HfO ⁺ , TiO ⁺ , TiO2 ^+, etc.; transition metal hydroxide cations such as ZrOH ⁺ , HfOH ⁺ , etc.

The type of the salt in the metal salt C is not particularly limited, and may be an inorganic salt or an organic salt. Examples of inorganic salts include hydrohalic acids such as hydrochloric acid, hydrobromic acid, and hydrofluoric acid, inorganic acid salts such as nitric acid, sulfuric acid, carbonic acid, silicic acid, boric acid, and phosphoric acid; sulfides; oxides; oxyhalides such as oxychlorides, oxybromides, and oxyfluorides; oxyinorganic acid salts such as oxynitrates, oxysulfates, oxycarbonates, oxysilicates, oxyborates, and oxyphosphates; and oxysulfides. Examples of organic salts include organic acid salts such as formic acid, acetic acid, propionic acid, benzoic acid, glycine acid, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid; organic sulfonic acids such as methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, and toluenesulfonic acid; organic phosphonic acids such as methylphosphonic acid, benzenephosphonic acid, and toluenephosphonic acid; organic phosphoric acids such as ethyl phosphoric acid; and oxyorganic acid salts such as oxyacetates. Among these, salts of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid are preferred, and salts of hydrochloric acid and nitric acid are more preferred. The technology disclosed herein can be preferably implemented, for example, in an embodiment in which the metal salt C is an oxytransition metal salt that is a salt of an oxytransition metal cation and an anion. In some preferred embodiments, the technology can be preferably implemented in an embodiment in which a salt of an oxytransition metal cation, such as ZrO ²⁺ , ZrO ⁺ , HfO ⁺ , TiO ⁺ , or TiO ^2+, is used with a nitrate ion (NO ³⁻ ), a sulfate ion (SO ₄ ²⁻ ), or a chloride ion (Cl ⁻ ).

Metal salt C, when dissolved in water, produces a polynuclear transition metal complex consisting of a transition metal and oxygen atoms and/or hydrogen. For example, when metal salt C such as zirconyl nitrate, zirconium sulfate, or zirconium chloride is dissolved in water, a polynuclear transition metal complex consisting of zirconium and oxygen atoms and/or hydrogen is produced. In the technology disclosed herein, metal salt C can also be preferably embodied in the form of a polynuclear transition metal complex consisting of a transition metal and oxygen atoms and/or hydrogen produced by dissolving in water. An example of a preferred polynuclear transition metal complex is a polynuclear transition metal complex consisting of zirconium and oxygen atoms and/or hydrogen.

The metal salt C is preferably a compound that is not oxidized by the oxidizing agent. From this viewpoint, by appropriately selecting the oxidizing agent and the metal salt C, it is possible to prevent the metal salt C from being oxidized by the oxidizing agent, thereby preventing the performance of the polishing composition from deteriorating over time (e.g., a decrease in the polishing removal rate, etc.). From this viewpoint, an example of a preferred metal salt C is zirconyl nitrate.

When the polishing composition contains metal salt C, the concentration (content) of metal salt C in the polishing composition is not particularly limited and can be appropriately set so as to achieve the desired effect depending on the purpose and manner of use of the polishing composition. The concentration of metal salt C may be, for example, approximately 1000 mM or less (i.e., 1 mol/L or less), may be 500 mM or less, or may be 300 mM or less. In some embodiments, the concentration of metal salt C is suitably 200 mM or less, preferably 100 mM or less, more preferably 50 mM or less, may be 30 mM or less, may be 20 mM or less, or may be 10 mM or less. When the polishing composition contains metal salt C, the lower limit of the concentration of metal salt C may be, for example, 0.1 mM or more, and from the viewpoint of properly exerting the effect of using metal salt C, it is advantageous to set it to 1 mM or more, preferably 5 mM or more, more preferably 10 mM or more (for example, 15 mM or more), and may be 18 mM or more, 20 mM or more, or 30 mM or more.

In the polishing composition containing the metal salt C, the relationship between the concentration of the metal salt C and the content of the inorganic particles is not particularly limited, and can be appropriately set so as to achieve the desired effect according to the purpose of use and the mode of use. The ratio of the concentration CC of the metal salt C (the total concentration of a plurality of metal salts C) [mM] to the content Wip of the inorganic particles (the total content of a plurality of inorganic particles) [wt %], i.e., CC/Wip, can be, for example, 0.05 or more, and is preferably 0.1 or more, and may be 0.2 or more, preferably 1 or more, more preferably 3 or more, may be 5 or more, or may be 10 or more. The larger CC/Wip is, the greater the contribution of chemical polishing to the contribution of mechanical polishing tends to be. In some embodiments, CC/Wip may be 12 or more, 15 or more, or 18 or more. In some other embodiments, CC/Wip may be 50 or more, 100 or more, 150 or more, 200 or more, or 250 or more. The upper limit of C/Wip is not particularly limited, but from the viewpoint of storage stability of the polishing composition, it may be, for example, about 20,000 or less, 10,000 or less, 5,000 or less, 2,500 or less, or 1,000 or less. In some embodiments, CC/Wip may be 100 or less, 50 or less, 40 or less, or 30 or less.
In the above "CC/Wip,""CC" represents the numerical value when the concentration of metal salt C in the polishing composition is expressed in units of "mM," and "Wip" represents the numerical value when the content of inorganic particles in the polishing composition is expressed in units of "weight %," and both Wip and CC are dimensionless numbers.

(water)
The polishing composition disclosed herein typically contains water. As the water, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. can be preferably used. The polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be uniformly mixed with water, if necessary. Usually, it is appropriate that 90% by volume or more of the solvent contained in the polishing composition is water, preferably 95% by volume or more is water, and more preferably 99 to 100% by volume is water.

(acid)
The polishing composition may contain an acid as necessary for the purpose of adjusting pH or improving the polishing removal rate. Both inorganic and organic acids can be used as the acid. Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, and carbonic acid. Examples of organic acids include aliphatic carboxylic acids such as formic acid, acetic acid, and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, organic sulfonic acid, and organic phosphonic acid. These can be used alone or in combination of two or more. When an acid is used, the amount of the acid is not particularly limited, and can be determined according to the purpose of use (e.g., pH adjustment). Alternatively, in some embodiments of the polishing composition disclosed herein, the composition may be substantially free of acid.

(Basic Compound)
The polishing composition may contain a basic compound as necessary for the purpose of adjusting pH or improving the polishing removal rate. Here, the basic compound refers to a compound that has the function of increasing the pH of the polishing composition by being added to the polishing composition. Examples of basic compounds include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; carbonates and bicarbonates such as ammonium hydrogen carbonate, ammonium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, and sodium carbonate; ammonia; quaternary ammonium compounds such as quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; and other amines, phosphates, hydrogen phosphates, and organic acid salts. The basic compounds may be used alone or in combination of two or more. When a basic compound is used, the amount used is not particularly limited, and may be used in accordance with the purpose of use (e.g., pH adjustment). Alternatively, in some embodiments of the polishing composition disclosed herein, the composition may be substantially free of a basic compound.

(Other ingredients)
The polishing composition disclosed herein may further contain, as necessary, known additives that can be used in polishing compositions (for example, polishing compositions used for polishing high-hardness materials such as silicon carbide), such as chelating agents, thickening agents, dispersants, surface protective agents, wetting agents, surfactants, rust inhibitors, preservatives, and antifungal agents, within the scope that does not impair the effects of the present invention. The content of the above additives may be appropriately set depending on the purpose of their addition, and detailed explanations are omitted since they do not characterize the present invention.

(pH)
The pH of the polishing composition is suitably about 1 to 12. When the pH is in the above range, a practical polishing removal rate is easily achieved. In some embodiments, the pH may be 12.0 or less, 11.0 or less, 10.0 or less, 9.0 or less, less than 9.0, 8.0 or less, less than 8.0, 7.0 or less, less than 7.0, or 6.0 or less. When a metal salt is contained, from the viewpoint of more easily exerting the effect of improving the polishing removal rate by using a metal salt (e.g., metal salt B), in some embodiments, the pH of the polishing composition is preferably less than 6.0, 5.0 or less, less than 5.0, 4.0 or less, or less than 4.0. The pH may be, for example, 1.0 or more, 1.5 or more, 2.0 or more, or 2.5 or more.

The method for preparing the polishing composition disclosed herein is not particularly limited. For example, the components contained in the polishing composition may be mixed using a well-known mixing device such as a blade stirrer, ultrasonic disperser, or homomixer. The manner in which these components are mixed is not particularly limited, and for example, all the components may be mixed at once, or may be mixed in an appropriately set order.

The polishing composition disclosed herein may be a one-component type or a multi-component type, including a two-component type. For example, the polishing composition may be configured such that part A containing some of the components (e.g., components other than water) of the polishing composition and part B containing the remaining components are mixed and used to polish an object to be polished. The multi-component polishing composition may further contain part C in addition to the above-mentioned parts A and B. These may be stored separately before use, for example, and mixed at the time of use to prepare a one-component polishing composition. When mixed, water for dilution may be further mixed. In a preferred embodiment, the multi-component polishing composition disclosed herein contains particles (inorganic particles or resin particles) and water in part A, and contains an oxidizing agent and water in part B. This embodiment can improve the storage stability of the polishing composition. The optionally used part C may or may not contain inorganic particles, resin particles, and a portion of the oxidizing agent.

<Object to be polished>
The object to be polished by the polishing composition disclosed herein is not particularly limited. For example, the polishing composition disclosed herein can be applied to polishing a substrate having a surface composed of a compound semiconductor material, that is, a compound semiconductor substrate. The constituent material of the compound semiconductor substrate is not particularly limited, and may be, for example, II-VI group compound semiconductors such as cadmium telluride, zinc selenide, cadmium sulfide, cadmium mercury telluride, zinc cadmium telluride, etc.; III-V group compound semiconductors such as gallium nitride, gallium arsenide, gallium phosphide, indium phosphide, aluminum gallium arsenide, gallium indium arsenide, indium gallium nitride arsenide, aluminum gallium indium phosphide, etc.; IV-IV group compound semiconductors such as silicon carbide and germanium silicide; etc. The object to be polished may be composed of a plurality of these materials. In a preferred embodiment, the polishing composition disclosed herein can be applied to polishing a substrate having a surface composed of a chemical semiconductor material that is not an oxide (i.e., a non-oxide). In polishing a substrate having a surface composed of a non-oxide chemical semiconductor material, the polishing-accelerating effect of the oxidizing agent contained in the polishing composition disclosed herein is easily and suitably exhibited.

The polishing composition disclosed herein can be preferably used for polishing the surface of an object to be polished having a Vickers hardness of, for example, 500 Hv or more. The Vickers hardness is preferably 700 Hv or more, for example, 1000 Hv or more, or 1500 Hv or more. The Vickers hardness of the material to be polished may be 1800 Hv or more, 2000 Hv or more, or 2200 Hv or more. The upper limit of the Vickers hardness of the surface of the object to be polished is not particularly limited, and may be, for example, approximately 7000 Hv or less, 5000 Hv or less, or 3000 Hv or less. In this specification, the Vickers hardness can be measured based on JIS R 1610:2003. The international standard corresponding to the above JIS standard is ISO 14705:2000.

Materials having a Vickers hardness of 1500 Hv or more include silicon carbide, silicon nitride, titanium nitride, gallium nitride, etc. The object to be polished in the technology disclosed herein may have a single crystal surface of the above material that is mechanically and chemically stable. In particular, the surface of the object to be polished is preferably composed of either silicon carbide or gallium nitride, and more preferably composed of silicon carbide. Silicon carbide is expected to be a compound semiconductor substrate material with low power loss and excellent heat resistance, etc., and the practical advantage of improving productivity by increasing the polishing removal rate is particularly great. The technology disclosed herein can be particularly preferably applied to polishing the single crystal surface of silicon carbide.

<Polishing method>
The polishing composition disclosed herein can be used for polishing an object to be polished, for example, in an embodiment including the following operations.
That is, prepare a polishing liquid (slurry) containing any of the polishing compositions disclosed herein. The preparation of the polishing liquid may include the polishing composition being adjusted in concentration (e.g., diluted), adjusted in pH, etc. to prepare the polishing liquid. Alternatively, the polishing composition may be used as it is as the polishing liquid. In addition, in the case of a multi-agent type polishing composition, the preparation of the polishing liquid may include mixing the agents, diluting one or more agents before the mixing, diluting the mixture after the mixing, etc.
Next, the polishing liquid is supplied to the object to be polished, and the object is polished by a method that is generally used by those skilled in the art. For example, the object to be polished is set in a general polishing device, and the polishing liquid is supplied to the surface of the object to be polished through the polishing pad of the polishing device. Typically, the polishing liquid is continuously supplied, and the polishing pad is pressed against the surface of the object to be polished, and the two are moved relatively (for example, rotated). Through this polishing process, the polishing of the object to be polished is completed.

The above-mentioned contents (concentrations) and content (concentration) ratios for each component that may be contained in the polishing composition in the technology disclosed herein typically refer to the contents and content ratios in the polishing composition when it is actually supplied to the object to be polished (i.e., at the point of use), and therefore can be read as the contents and content ratios in the polishing liquid.

According to this specification, a polishing method for polishing an object to be polished (typically, a material to be polished) and a method for manufacturing a polished product using the polishing method are provided. The polishing method is characterized by including a step of polishing an object to be polished using the polishing composition disclosed herein. A preferred embodiment of the polishing method includes a step of performing preliminary polishing (preliminary polishing step) and a step of performing finish polishing (finish polishing step). In a typical embodiment, the preliminary polishing step is a polishing step arranged immediately before the finish polishing step. The preliminary polishing step may be a single-stage polishing step or a multiple-stage polishing step of two or more stages. The finish polishing step here refers to a step of performing finish polishing on an object to be polished that has been subjected to preliminary polishing, and is the polishing step arranged last (i.e., the most downstream) of the polishing steps that are performed using a polishing slurry containing abrasive grains. In such a polishing method that includes a preliminary polishing step and a finish polishing step, the polishing composition disclosed herein may be used in the preliminary polishing step, may be used in the finish polishing step, or may be used in both the preliminary polishing step and the finish polishing step.

Preliminary polishing and finish polishing can be applied to both polishing with a single-sided polishing machine and polishing with a double-sided polishing machine. With a single-sided polishing machine, the object to be polished is attached to a ceramic plate with wax or held using a holder called a template, and one side of the object to be polished is polished by pressing a polishing pad against one side of the object to be polished while supplying a polishing composition and moving the two relative to each other. The above movement is, for example, rotational movement. With a double-sided polishing machine, the object to be polished is held using a holder called a carrier, and while supplying a polishing composition from above, a polishing pad is pressed against the opposing side of the object to be polished and they are rotated in relative directions to polish both sides of the object to be polished simultaneously.

The above polishing conditions are appropriately set based on the type of material to be polished, the target surface properties (specifically, smoothness), the polishing removal rate, etc., and are not limited to specific conditions. For example, the polishing composition disclosed herein can be used in a wide pressure range, for example, from 10 kPa to 150 kPa. From the viewpoint of improving the polishing removal rate, in some embodiments, the above processing pressure may be, for example, 5 kPa or more, 10 kPa or more, 20 kPa or more, 30 kPa or more, or 40 kPa or more, and can be 100 kPa or less, 80 kPa or less, or 60 kPa or less. The polishing composition disclosed herein can be preferably used for polishing under processing conditions of, for example, 30 kPa or more or higher, and the productivity of the target object (polished object) obtained through such polishing can be increased. Note that the processing pressure here is synonymous with the polishing pressure.

The polishing pad used in each polishing process disclosed herein is not particularly limited. For example, any of nonwoven fabric type, suede type, and hard foam polyurethane type may be used. In some embodiments, a hard foam polyurethane type polishing pad may be preferably used. Note that the polishing pad used in the technology disclosed herein is a polishing pad that does not contain abrasive grains.

The object to be polished that has been polished by the method disclosed herein is typically washed after polishing. This washing can be carried out using an appropriate cleaning liquid. There are no particular limitations on the cleaning liquid used, and any known or commonly used liquid can be appropriately selected and used.

The polishing method disclosed herein may include any other steps in addition to the preliminary polishing step and the finish polishing step. Examples of such steps include a mechanical polishing step and a lapping step that are performed before the preliminary polishing step. In the mechanical polishing step, the object to be polished is polished using a liquid in which diamond abrasive grains are dispersed in a solvent. In some preferred embodiments, the dispersion liquid does not contain an oxidizing agent. The lapping step is a step in which the surface of a polishing table, for example a cast iron table, is pressed against the object to be polished to polish it. Therefore, a polishing pad is not used in the lapping step. The lapping step is typically performed by supplying abrasive grains between the polishing table and the object to be polished. The abrasive grains are typically diamond abrasive grains. The polishing method disclosed herein may also include an additional step before the preliminary polishing step or between the preliminary polishing step and the finish polishing step. The additional step is, for example, a cleaning step or a polishing step.

<Method of manufacturing polished object>
The technology disclosed herein may include a method for manufacturing an abrasive, which includes a polishing step using any of the polishing methods described above, and the provision of an abrasive manufactured by the method. The above-mentioned method for manufacturing an abrasive is, for example, a method for manufacturing a silicon carbide substrate. That is, according to the technology disclosed herein, a method for manufacturing an abrasive, which includes polishing an object to be polished having a surface made of a high-hardness material by applying any of the polishing methods disclosed herein, and an abrasive manufactured by the method are provided. According to the above manufacturing method, a substrate manufactured through polishing, such as a silicon carbide substrate, can be efficiently provided.

The matters disclosed in this specification include the following.
[1] A polishing composition comprising inorganic particles, an oxidizing agent, and resin particles, wherein the oxidizing agent comprises a composite metal oxide, and the ratio (Nrp/Nip) of the number of the inorganic particles (Nip) to the number of the resin particles (Nrp) is 80 or more.
[2] The polishing composition according to the above [1], wherein the inorganic particles include oxide particles.
[3] The polishing composition according to [2] above, wherein the oxide particles contain alumina.
[4] The polishing composition according to [2] above, wherein the oxide particles contain silica.
[5] The polishing composition according to any one of [1] to [4] above, wherein the polishing composition has a pH of 9 or less.
[6] The polishing composition according to any one of [1] to [5] above, wherein the composite metal oxide is a permanganic acid.
[7] The polishing composition according to any one of [1] to [6] above, wherein the resin particles include one selected from the group consisting of polyolefin resin, acrylic resin, styrene-acrylic resin, vinyl chloride resin, melamine resin, polyurethane resin, and acrylic-urethane resin.
[8] The polishing composition according to the above [7], wherein the resin particles contain a crosslinked acrylic resin.
[9] The polishing composition according to the above [7], wherein the resin particles contain a crosslinked styrene-acrylic resin.
[10] The polishing composition according to any one of [1] to [9] above, wherein the ratio (Nrp/Nip) is 50,000 or less.
[11] The polishing composition according to any one of [1] to [10] above, wherein the resin particles have an average particle size of 5 nm or more and 3 μm or less.
[12] The polishing composition according to any one of [1] to [11] above, which is used for polishing a material having a Vickers hardness of 1500 Hv or more.
[13] The polishing composition according to any one of [1] to [12] above, which is used for polishing silicon carbide.

Below, several examples of the present invention are described, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "%" is based on weight unless otherwise specified.

<Preparation of Polishing Composition>
(Example 1, Example 2, Comparative Examples 3 to 9)
Resin particles, oxidizing agent, inorganic particles, and deionized water are mixed to prepare a polishing composition.The polishing composition contains 1.6 wt% oxidizing agent and 5.9 wt% inorganic particles.The concentration of resin particles in the polishing composition, the ratio (Nrp/Nip) of the number concentration Nrp [pieces/L] of resin particles to the number concentration Nip [pieces/L] of inorganic particles used, and the resin particles, oxidizing agent, inorganic particles used are as shown in Table 1.

(Comparative Example 1 and Comparative Example 2)
An oxidizing agent, inorganic particles, and deionized water were mixed to prepare a polishing composition. The polishing composition contained 1.6 wt% of an oxidizing agent and 5.9 wt% of inorganic particles. In Comparative Example 2, an acid was added to the composition of Comparative Example 1 to adjust the pH. The oxidizing agent and inorganic particles used were as shown in Table 1.

<Polishing of the object to be polished>
A SiC wafer was pre-polished using a preliminary polishing composition containing alumina particles. The polished SiC wafer was polished under the following conditions using the polishing composition according to each example as it is as a polishing liquid.
[Polishing conditions]
Polishing equipment: Fujikoshi Machinery Industry Co., Ltd., model "RDP-500"
Polishing pad: Nitta Haas "SUBA800XY" (non-woven fabric type)
Processing pressure: 29.4 kPa
Platen rotation speed: 100 rpm Head rotation speed: 100 rpm Polishing liquid supply rate: 20 mL/min Polishing liquid usage method: pour-over Polishing time: 1 hour Polishing object: 1-inch SiC wafer (conductivity type: n-type, crystal type 4H-SiC, off angle of main surface (0001) to C-axis: 4°), Si surface, 1 wafer/batch Polishing liquid temperature: 23°C

<Measurement and Evaluation>
(Polishing removal rate)
Under the above polishing conditions, a SiC wafer was polished using each polishing composition, and the polishing removal rate was calculated according to the following formulas (1) and (2). The density of SiC was 3.21 g/ ^cm3 , and the area to be polished was 19.62 ^cm2 .
(1) Polishing stock removal [cm]=difference in weight of SiC wafer before and after polishing [g]/density of SiC [g/cm ³ ]/area to be polished [cm ² ]
(2) Polishing removal rate [nm/h]=polishing removal amount [cm]×10 ⁷ /polishing time [h]

The results were converted into relative values, with the polishing removal rate for Comparative Example 1 taken as 100%. A higher value indicates a better polishing removal rate.

(Coefficient of Friction)
Under the above polishing conditions, the friction coefficient was measured when polishing a SiC wafer using each polishing composition. When measuring the friction coefficient, a template using a suede backing material was used as a wafer holder. The wafer was attached so that it protruded from the template by 200 μm or more. During polishing, the wafer was kept in a water-tensioned state against the suede material. The friction coefficient was directly adopted as the value output from the polishing device.

The results were converted into relative values, with the friction coefficient for Comparative Example 1 taken as 100%. A smaller value indicates a greater reduction in friction.

As shown in Table 1, the polishing composition of the example having an Nrp/Nip ratio of 80 or more was able to improve the polishing removal rate and reduce friction compared to the polishing composition of Comparative Example 1.

Claims (13)

1. A polishing composition comprising inorganic particles, an oxidizing agent, and resin particles,
   the oxidizing agent comprises a complex metal oxide;
   The polishing composition has a ratio (Nrp/Nip) of the number of the inorganic particles (Nip) to the number of the resin particles (Nrp) of 80 or more.
2. The polishing composition according to claim 1, wherein the inorganic particles include oxide particles.
3. The polishing composition according to claim 2, wherein the oxide particles include alumina.
4. The polishing composition according to claim 2, wherein the oxide particles include silica.
5. The polishing composition according to claim 1, wherein the pH of the polishing composition is 9 or less.
6. The polishing composition according to claim 1, wherein the composite metal oxide is a permanganate.
7. The polishing composition according to claim 1, wherein the resin particles include one selected from the group consisting of polyolefin resin, acrylic resin, styrene-acrylic resin, vinyl chloride resin, melamine resin, polyurethane resin, and acrylic-urethane resin.
8. The polishing composition according to claim 7, wherein the resin particles include a crosslinked acrylic resin.
9. The polishing composition according to claim 7, wherein the resin particles contain a cross-linked styrene-acrylic resin.
10. The polishing composition according to claim 1, wherein the ratio (Nrp/Nip) is 50,000 or less.
11. The polishing composition according to claim 1, wherein the average particle size of the resin particles is 5 nm or more and 3 μm or less.
12. The polishing composition according to claim 1, which is used for polishing materials having a Vickers hardness of 1500 Hv or more.
13. The polishing composition according to claim 1, which is used for polishing silicon carbide.