TW202405129A - Polishing composition - Google Patents

Abstract

The present invention provides means for preventing sedimentation of abrasive grains and improving redispersibility of abrasive grains, while improving polishing performance. The present invention relates to a polishing composition comprising abrasive grains, an oxidant, a metal cation exhibiting a hydrated metal ion pKa of less than 7.0, a metal salt A which is a salt with an anion, a layered compound, and a dispersant, the polishing composition including the metal salt A at a concentration of 8 mM or more.

Description

Grinding composition

The present invention relates to a polishing composition.

Generally speaking, in the polishing of semiconductor substrates such as silicon wafers and silicon carbide, along with the high performance and high integration density of semiconductor devices, not only the surface quality has been improved, but also in order to cope with the increase in demand in recent years, manufacturing has been improved. Efficiency has also become an important issue. As a technology for solving this problem, for example, Japanese Patent Application Laid-Open No. 2012-248569 discloses an abrasive characterized by containing an oxidizing agent containing a transition metal with a redox potential of 0.5 V or more, and an average secondary particle size. It is cerium oxide particles below 0.5 μm and dispersion medium.

However, the polishing composition described in Japanese Patent Application Laid-Open No. 2012-248569 has a problem that the polishing performance (for example, the polishing removal rate or the surface roughness of the polishing object) is unstable due to poor dispersibility of the abrasive grains. , and during the production or use of the polishing composition, the abrasive grains settle in the pipes or slurry supply pipes, causing clogging of the pipes and the like. Furthermore, there is a problem that the redispersibility of abrasive grains after long-term storage is also poor. In addition, there is a strong demand to increase the grinding and removal speed of materials with higher hardness such as silicon carbide.

The present invention was completed in view of the above problems, and its purpose is to provide a means of improving polishing performance while preventing the settling of abrasive grains and improving the redispersibility of abrasive grains. In order to solve the above-mentioned problems, the present inventors have repeatedly conducted intensive research. As a result, it was found that the above problems can be solved by a polishing composition containing abrasive grains, an oxidizing agent, a metal salt A, a layered compound, and a dispersion medium, and containing the metal salt A at 8 mM, and the above metal Salt A is a salt of a metal cation and anion whose pKa of the hydrated metal ion is less than 7.0. And based on the above knowledge, the present invention was completed.

Hereinafter, the structure of the polishing composition of the present invention will be described in detail. In addition, this invention is not limited only to the following embodiment. In addition, in this specification, unless otherwise stated, the operation and physical properties are measured under the conditions of room temperature (20°C or more and 25°C or less)/relative humidity of 40%RH or more and 50%RH or less.

[abrasive grain] The polishing composition of the present invention contains abrasive particles. Abrasive grains have the function of mechanically grinding objects to be ground.

Specific examples of the abrasive grains used in the present invention include metal oxides such as alumina, silica, ceria, zirconium oxide, titania, and manganese oxide. ; Metal carbides such as silicon carbide and titanium carbide; metal nitrides such as silicon nitride and titanium nitride; metal borides such as titanium boride and tungsten boride. This abrasive grain can be used individually or in mixture of 2 or more types. In addition, a commercially available product or a synthetic product may be used as this abrasive grain.

Among these abrasive grains, at least one selected from the group consisting of metal oxides and metal carbides is preferred from the viewpoint that those having various particle sizes can be easily obtained and an excellent polishing removal rate can be obtained. One, preferably alumina.

The average secondary particle diameter of the abrasive grains is preferably 0.01 μm or more, more preferably 0.05 μm or more, further preferably 0.1 μm or more, particularly preferably 0.2 μm or more. As the average secondary particle size of the abrasive grains increases, the grinding removal speed of the grinding object increases. In addition, the average secondary particle size of the abrasive grains is preferably 10.0 μm or less, more preferably 5.0 μm or less, further preferably 3.0 μm or less, further preferably 1.8 μm or less, still more preferably 1.5 μm or less, and particularly preferably 1.0 μm or less, preferably 0.5 μm or less. As the volume average particle size of the abrasive particles decreases, it is easier to obtain a surface with fewer defects and less roughness. According to the above, the average secondary particle diameter of the abrasive grains is preferably from 0.01 μm to 10.0 μm, more preferably from 0.05 μm to 5.0 μm, further preferably from 0.1 μm to 3.0 μm, and particularly preferably from 0.2 μm to 1.0 Below μm.

Furthermore, the average secondary particle diameter of the abrasive grains in this specification is measured based on the laser diffraction analysis scattering method unless otherwise specified. Specifically, the measurement can be performed using a laser diffraction analysis/scattering particle size distribution measuring device (trade name "LA-950") manufactured by Horiba Manufacturing Co., Ltd.

The concentration (content) of the abrasive grains in the polishing composition is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, and still more preferably 0.01 mass% or more. As the concentration (content) of abrasive particles increases, the grinding removal speed increases. The concentration (content) of the abrasive grains in the polishing composition may be 0.05% by mass or more, or may be 0.1% by mass or more.

Moreover, the concentration (content) of the abrasive grains in the polishing composition is preferably 30 mass% or less, more preferably 25 mass% or less, and still more preferably 10 mass% or less. As the concentration (content) of the abrasive grains decreases, the manufacturing cost of the polishing composition decreases, and by polishing using the polishing composition, it is easier to obtain a surface with fewer defects such as scratches. The concentration (content) of the abrasive grains in the polishing composition may be 8 mass% or less, or may be 7 mass% or less.

According to the above, the concentration (content) of the abrasive grains in the polishing composition is preferably 0.001 mass % or more and 30 mass % or less, more preferably 0.005 mass % or more and 25 mass % or less, and still more preferably 0.01 mass % or more 10 mass %. mass% or less. Moreover, the concentration (content) of the abrasive grains in the polishing composition may be 0.05 mass% or more and 8 mass% or less, or may be 0.1 mass% or more and 7 mass% or less.

[Oxidant] The polishing composition of the present invention contains an oxidizing agent. The oxidizing agent produces an oxidation reaction with the substrate surface during the grinding process, thereby reducing the hardness of the surface and making the surface fragile. By using oxidants, the grinding removal speed can be effectively increased.

The oxidizing agent is not particularly limited as long as it has a redox potential sufficient to oxidize the substrate surface. For example, the oxidizing agent may be a substance that has a higher redox potential than the redox potential of the substrate material at the pH value at which polishing is performed. Here, the pH value at which the above-mentioned grinding is carried out is usually the same as the pH value of the grinding composition. Furthermore, the redox potential of the substrate material was determined by dispersing the powder of the material in water to form a slurry, adjusting the slurry to the same pH value as the polishing composition, and then using a commercially available oxidizing agent. The value obtained by measuring the oxidation-reduction potential of the slurry (relative to the oxidation-reduction potential of a standard hydrogen electrode at a liquid temperature of 25°C) was measured with a reduction potentiometer. In addition, the oxidizing agent in this specification does not include the metal salt A mentioned later.

Specific examples of the oxidizing agent include: peroxides such as hydrogen peroxide; nitric acids such as iron nitrate, silver nitrate, and aluminum nitrate; persulfuric acids such as persulfuric acid such as peroxymonosulfuric acid and peroxydisulfuric acid; and chlorine such as chloric acid. Acids; perchloric acids such as perchloric acid; bromic acids such as bromic acid; iodic acids such as iodic acid; periodic acids; iron acids such as potassium ferrite; permanganic acids such as sodium permanganate and potassium permanganate; potassium chromate Chromic acids such as , potassium dichromate; vanadic acids such as ammonium vanadate, sodium vanadate, potassium vanadate; ruthenic acids such as perruthenic acid or its salts; molybdic acid, ammonium molybdate as its salt, disodium molybdate, etc. Molybdic acids; rhenic acids such as perrhenic acid or its salts; tungstic acids such as tungstic acid and disodium tungstate as its salt. These may be used individually by 1 type, and may be used in combination of 2 or more types appropriately.

In some preferred aspects, the polishing composition includes a complex metal oxide as an oxidizing agent. Examples of the composite metal oxide include nitric acids, ferric acids, permanganic acids, chromic acids, vanadic acids, ruthenic acids, molybdic acids, rhenic acids, and tungstic acids. Among these, ferric acids, permanganic acids, and chromic acids are more preferred, and permanganic acids are even more preferred. One type of composite metal oxide may be used alone, or two or more types may be used in appropriate combination.

The polishing composition disclosed here may further contain an oxidizing agent other than the above-described composite metal oxide, or may not contain an oxidizing agent other than the above-described composite metal oxide. The technology disclosed here can be preferably implemented in an aspect that does not substantially contain oxidizing agents other than the above-mentioned composite metal oxides (such as hydrogen peroxide) as oxidizing agents.

The concentration (content) of the oxidizing agent in the polishing composition is preferably 0.001 mol/L or more. From the perspective of increasing the grinding removal speed, in several aspects, the concentration (content) of the oxidizing agent is preferably 0.005 mol/L or more, more preferably 0.01 mol/L or more, and further preferably 0.05 mol/L or more. . In several preferred aspects, the concentration (content) of the oxidizing agent is above 0.10 mol/L, may be above 0.15 mol/L, may also be above 0.20 mol/L, for example, above 0.25 mol/L. In addition, from the viewpoint of surface quality after polishing, the concentration (content) of the above-mentioned oxidizing agent is preferably 10 mol/L or less, preferably 5 mol/L or less, and more preferably 3 mol/L or less. (For example, below 2.5 mol/L or below 2 mol/L). In several aspects, the concentration (content) of the oxidizing agent may be less than 2 mol/L, may be less than 1.5 mol/L, or may be less than 1.5 mol/L.

According to the above, the concentration (content) of the oxidizing agent in the polishing composition is preferably from 0.001 mol/L to 10 mol/L, preferably from 0.005 mol/L to 5 mol/L, and more preferably from 0.01 mol/L to 5 mol/L. Above 3 mol/L and below. In several aspects, the concentration (content) of the oxidizing agent in the polishing composition may be 0.05 mol/L or more and 2.5 mol/L or less, or may be 0.10 mol/L or more and 2 mol/L or less. Furthermore, in several preferred aspects, the concentration (content) of the oxidizing agent in the polishing composition can be 0.15 mol/L or more and less than 2 mol/L, and can be 0.20 mol/L or more and 1.5 mol/L or less. , it can also be above 0.20 mol/L and less than 1.5 mol/L.

[Metal Salt A] The polishing composition of the present invention contains metal salt A. Metal salt A is a salt of metal cations and anions whose pKa of hydrated metal ions is less than 7.0. Furthermore, in this specification, a metal cation refers to a cation containing a metal. That is, the metal cation may be a cation composed only of a metal, or may be a cation composed of a metal and a non-metal. Metal salt A may be used individually by 1 type, or may be used in combination of 2 or more types. By including the metal salt A in addition to the oxidizing agent in the polishing composition for polishing silicon carbide, the polishing removal speed and storage stability can be improved.

Without wishing to be bound by theory, the reason why this effect is obtained is thought to be, for example, as follows. That is, in polishing by supplying a polishing composition containing an oxidizing agent to a polishing object having a surface made of silicon carbide, the oxidizing agent contained in the polishing composition oxidizes the surface of the silicon carbide. And make it brittle, which can help increase the grinding removal speed. However, the above-mentioned oxidation may cause an increase in the pH value of the polishing composition supplied to the object to be polished. Thereby, if the pH value of the polishing composition supplied to the object to be polished increases from the initial pH value (that is, the pH value of the polishing composition supplied to the object to be polished) during the grinding of the object to be polished, and the pH value of the polishing composition supplied to the object to be polished is increased and If the pH value deviates from the appropriate pH range, the chemical polishing performance of the polishing composition on the above-mentioned polishing object will be reduced. It is considered that if a metal salt A containing a metal cation having a pKa of a hydrated metal ion less than 7.0 is contained in a polishing composition containing an oxidizing agent, the metal salt A exerts a buffering effect and suppresses an increase in the pH value of the polishing composition, thereby suppressing an increase in the pH value of the polishing composition. By maintaining the pH value within a suitable pH range, the chemical polishing performance of the polishing composition is maintained, thereby increasing the polishing removal speed. In addition, it is believed that the buffering effect of the metal salt A contributes to improving storage stability. However, the above discussion does not limit the scope of the present invention.

In several aspects, as the metal salt A, it is preferable to use a salt of a metal cation and an anion in which the pKa of the hydrated metal ion is 6.5 or less. Examples of metal cations whose pKa of the hydrated metal ion is 6.5 or less include Al ³⁺ (the pKa of the hydrated metal ion is 5.0), Cr ³⁺ (the pKa of the hydrated metal ion is 4.2), In 3+ (the pKa of the hydrated metal ion is 4.2), and In ³⁺ (the pKa of the hydrated metal ion is 5.0). The pKa of the ion is 4.0), Ga ³⁺ (the pKa of the hydrated metal ion is 2.6), Fe ³⁺ (the pKa of the hydrated metal ion is 2.2), Hf ⁴⁺ (the pKa of the hydrated metal ion is 0.2), Zr ⁴⁺ ( The pKa of the hydrated metal ion is -0.3), Ce ⁴⁺ (the pKa of the hydrated metal ion is -1.1), and Ti ⁴⁺ (the pKa of the hydrated metal ion is -4.0), but is not limited to these. In several aspects, the pKa of the hydrated metal ion may be less than 6.5, may be less than 6.0, may be less than 6.0, may be less than 5.5, may be less than 5.0, may be less than 4.5, may be less than 4.0, may be Below 3.5, it can also be below 3.0. In addition, the pKa of the above-mentioned hydrated metal ion is preferably about -5.0 or more, it can be -1.5 or more, it can be -0.5 or more, preferably it is 0.0 or more, more preferably it is 0.5 or more, it can be 1.0 or more, it can be 1.5 or more, it can be It is above 2.0, and it can also be above 2.5. The valence of the above-mentioned metal cation in the metal salt A may be, for example, divalent, trivalent, or tetravalent. In several aspects, metal salt A, which is a salt of a cation and anion of a trivalent metal, may be preferably used.

According to the above, the pKa of the above-mentioned hydrated metal ion may be -5.0 or more and less than 6.5, it may be -1.5 or more and less than 6.5, it may be -1.5 or more and less than 6.0, it may be -0.5 or more but less than 6.0, it may also be - Above 0.5 and below 5.5.

The above-mentioned metal cations in the metal salt A may be, for example, cations containing metals belonging to Group 3 to Group 16 of the periodic table, preferably cations containing metals belonging to Group 4 to Group 14 of the periodic table, more preferably It is a cation containing metals belonging to groups 6 to 14 of the periodic table. The technology disclosed here can be preferably implemented using, for example, the metal salt A which is a salt containing a cation and anion of a metal belonging to Group 13 of the periodic table.

In several aspects, as the metal salt A, a salt that buffers the pH value to 2.5 or more and 5.5 or less (for example, 3.0 or more and 4.5 or less) can be preferably used. The pH value buffered by the metal salt A can be determined by titrating the aqueous solution of the metal salt A with sodium hydroxide.

The metal salt A may be an inorganic acid salt or an organic acid salt. Examples of inorganic acid salts include 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 formic acid, acetic acid, propionic acid, benzoic acid, glycine, butyric acid, citric acid, tartaric acid, carboxylic acids such as trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, Salts of organic sulfonic acids such as benzene sulfonic acid and toluene sulfonic acid, organic phosphonic acids such as methylphosphonic acid, benzene phosphonic acid and toluene phosphonic acid, and organic phosphoric acids such as ethyl phosphoric 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 here can be preferably implemented in the following manner: as the metal salt A, use a salt selected from the group consisting of Al ³⁺ , Cr ³⁺ , Fe ³⁺ , In ³⁺ , Ga ³⁺ , and Zr ⁴⁺ The cation in the group is selected from the group consisting of nitrate ion (NO ^3- ), chloride ion (Cl ^- ), sulfate ion (SO ₄ ^2- ) and acetate ion (CH ₃ COO ^- ) Anionic salt.

Metal salt A is preferably a water-soluble salt. By using water-soluble metal salt A, a good surface with fewer defects such as scratches can be formed efficiently.

The concentration (content) of the metal salt A in the polishing composition is not particularly limited, and can be appropriately set to achieve the desired effect according to the purpose or usage pattern of the polishing composition. The concentration (content) of the metal salt A in the polishing composition may be, for example, about 1000 mM or less, 500 mM or less, or 300 mM or less. From the viewpoint of easily and effectively balancing the polishing removal speed and storage stability, in several aspects, the concentration (content) of the metal salt A in the polishing composition is preferably 200 mM or less, preferably 200 mM or less. It may be 100 mm or less, more preferably 50 mm or less, it may be 40 mm or less, it may be 30 mm or less, it may be 20 mm or less, it may be 10 mm or less. The concentration (content) of the metal salt A in the polishing composition can be, for example, 0.1 mM or more. From the viewpoint of appropriately exerting the effect of the metal salt A, it needs to be 8 mM or more, and preferably it is 10 mM or more. , more preferably, it is set to 15 mM or more (for example, 20 mM or more). The technology disclosed here can also be preferably implemented in an aspect where the concentration (content) of the metal salt A in the polishing composition is 25 mM or more or 30 mM or more. Furthermore, 1 mM=1 mmol/L.

According to the above, the concentration (content) of the metal salt A in the polishing composition can be 0.1 to 1000 mM, 8 to 500 mM, or 10 to 300 mM. In several aspects, the concentration (content) of the metal salt A in the polishing composition is preferably 15 mM or more and 200 mM or less, preferably 20 mM or more and 100 mM or less, more preferably 15 mM. It may be above 50 mM and below, it may be above 20 mM and below 40 mM, or it may be above 20 mM and below 30 mM. Furthermore, in several aspects, the concentration (content) of the metal salt A in the polishing composition may be 0.1 mm or more and 20 mm or less, or may be 0.1 mm or more and 10 mm or less.

Although it is not particularly limited, from the viewpoint of better exerting the effect produced by containing the metal salt A in the polishing composition containing the oxidizing agent, the concentration of the metal salt A in the polishing composition (in the range of The ratio (C2/C1) of the equal total concentration of C2 [mM] in the case of a plurality of metal salts A and the equal total concentration of the oxidizing agent (the equal total concentration in the case of a plurality of oxidants) C1 [mM] It is preferably about 0.0002 or more, preferably 0.0005 or more, more preferably 0.0007 or more, and may be 0.001 or more, 0.003 or more, or 0.005 or more. From the viewpoint of further increasing the grinding removal speed, in several aspects, C2/C1 may be, for example, 0.073 or more, preferably 0.01 or more, 0.015 or more, or 0.02 or more. C2/C1 is not particularly limited, but is preferably about 200 or less, may be 100 or less, may be 75 or less, or may be 50 or less. In several preferred aspects, C2/C1 can be less than 20, can be less than 10, can be less than 5, can be less than 1, can be less than 0.6, can be less than 0.5, can be less than 0.3, or can be 0.2 or less. This concentration ratio (C2/C1) of the metal salt A and the oxidizing agent can better realize the improvement of the grinding removal speed obtained by the metal salt A.

According to the above, C2/C1 is preferably 0.0002 or more and 200 or less, more preferably 0.0005 or more and 100 or less, it can be 0.007 or more and 75 or less, or it can be 0.001 or more and 50 or more. In several aspects, C2/C1 can be, for example, 0.003 to 20, 0.005 to 10, 0.007 to 5, 0.01 to 1, 0.015 to 0.6, or 0.02. 0.5 or less, it can be 0.02 or more and 0.3 or less, or it can be 0.02 or more and 0.2 or less.

[Layered compound] In the polishing composition of the present invention, the layered compound does not form chemical bonds (such as covalent bonds, ionic bonds, coordination bonds, hydrogen bonds, etc.) with the abrasive particles, and the layered compound is not physically attached to the abrasive particles. The abrasive grains are not supported on the abrasive grains. That is, the layered compound can form a weak mutual attraction interaction with the abrasive particles due to the intermolecular force or electrostatic interaction with the abrasive particles, and can exist in a state of forming a three-dimensional hindrance between the abrasive particles. This suppresses the aggregation of the abrasive grains, and therefore it is considered that the effects of the present invention can be obtained by preventing sedimentation or improving redispersibility while maintaining polishing performance.

In addition, by storing the polishing composition at a predetermined temperature for a predetermined time after preparing the polishing composition, the weak interaction between the above-mentioned layered compound and the abrasive particles is promoted, which is considered to further enhance the effect of preventing the abrasive grains from settling or improving the redispersibility. Effect.

Furthermore, the above mechanism is based on speculation, and its accuracy or error does not affect the technical scope of the present invention.

The layered compound used in the present invention is not particularly limited as long as it exhibits the above-mentioned effects. Examples include: clay minerals represented by layered silicate compounds, two-dimensional sheets containing NbO ₆ octahedral units Layered niobate compounds with a similar structure, layered titanate compounds with a layered structure composed of triangular bipyramidal planes connected by TiO ₅ , or layered titanate compounds with a two-dimensional sheet structure containing TiO ₆ octahedral units, exist between the layers Metal phosphate of the OH group of phosphoric acid, a layered composite hydroxide with anions between the layers of hydroxides containing divalent and trivalent metal ions, with metal atoms surrounded by chalcogen atoms in a regular octahedral shape Or graphite such as metal chalcogen compounds with a triangular prism-shaped structure, boron nitride with a structure of strongly bonded atomic layers, natural graphite, artificial graphite, etc.

More specifically, for example, as the layered niobate compound, K ₄ Nb ₆ O ₁₇ , KNb ₃ O ₈ , HNb ₃ O ₈ , NaNbO ₃ , LiNbO ₃ , Cs ₄ Nb ₆ O ₁₇ , etc. can be exemplified; Examples of layered titanate compounds include: Na ₂ Ti ₃ O ₇ , K ₂ Ti ₄ O ₉ , K ₂ Ti ₂ O ₅ , Cs ₂ Ti ₅ O ₁₁ , Cs ₂ Ti ₆ O ₁₃ , etc.; as metals Examples of phosphates include layered zirconium phosphates such as α-Zr(HPO ₄ ) ₂ and γ-ZrPO ₄ ·H ₂ PO ₄ ; examples of layered composite hydroxides include aluminum magnesium carbonate; and examples of metal sulfur Examples of group element compounds include: MoS ₂ , WS ₂ , TaS ₂ , NbS ₂ , etc. These layered compounds may be used alone or in combination of two or more types. Among the above-described layered compounds, a layered silicate compound is preferred from the viewpoint that the effects of the present invention can be stably and efficiently obtained. Hereinafter, the layered silicate compound will be described.

(layered silicate compound) The layered silicate compound is a structure, which is characterized by a structure based on the plane connection of silicate tetrahedrons. The unit structure contains one or two silicate tetrahedral sheets and an alumina or magnesium oxide octave. Face body piece. There are cations such as sodium, potassium, and calcium between its layers (between unit structures). In addition, the layered silicate compound has a property of enabling relatively thin exfoliation of crystals.

The layered silicate compound used in the present invention may be a natural product, a synthetic product, a commercial product, or a mixture thereof. Examples of the synthesis method of the layered silicate compound include hydrothermal synthesis reaction method, solid phase reaction method, melt synthesis method, and the like.

Specific examples of the layered silicate compound include: talc, pyrophyllite, bentonite (saponite, lithium bentonite, sauconite, siliconite, bentonite, montmorillonite, aluminum bentonite, nontronite, etc.), vermiculite, mica (phlogopite, biotite, lepidolite, muscovite, orange glass, green scale stone, glauconite, etc.), chlorite (clinochlorite, oolitic clay Stone, nickel chlorite, manganese aluminum chlorite, aluminum chlorite, sillicite, etc.), brittle mica (green brittle mica, nacre mica, etc.), manganese zoisite, serpentine (leaf serpentine, lizardite, etc.) Serpentine, serpentine, magnesium chlorite, iron serpentine, magnetic chlorite, iron serpentine, dark nickel serpentine, etc.), kaolin (kaolinite, dikaiite, diopside achondrite, Polyhydric kaolin, etc.) etc.

These layered silicate compounds may be used alone or in combination of two or more types. Among them, bentonite (saponite, lithium bentonite, zinc bentonite, siliconite, bentonite) is preferred because it has excellent thixotropy or swelling properties and can easily further improve the anti-sedimentation or redispersibility of the abrasive grains. , montmorillonite, aluminum bentonite, nontronite, etc.), more preferably lithium bentonite (sodium-lithium bentonite) and bentonite (sodium bentonite).

The lower limit of the particle size of the layered silicate compound is preferably 0.01 μm or more, more preferably 0.02 μm or more, and further preferably 0.05 μm or more. As the particle size of the layered silicate compound increases, the anti-sedimentation or redispersibility of the abrasive particles increases. Moreover, the upper limit of the particle size of the layered silicate compound is preferably 10 μm or less, more preferably 8 μm or less, and still more preferably 5 μm or less. As the particle size of the layered silicate compound decreases, the surface accuracy increases. According to the above, the particle size of the layered silicate compound is preferably from 0.01 μm to 10 μm, more preferably from 0.02 μm to 8 μm, and further preferably from 0.05 μm to 5 μm.

In addition, in this specification, the particle diameter of a layered silicate compound is defined as the value calculated|required using an electron microscope. More specifically, the particle size of the layered silicate compound can be measured by the method described in the Examples.

The concentration (content) of the layered compound in the polishing composition is preferably 0.01 mass% or more, more preferably 0.02 mass% or more. From the perspective of improving the anti-sedimentation and dispersibility of abrasive particles, in several aspects, the concentration (content) of the layered compound in the polishing composition can be 0.05 mass% or more, and can be 0.08 mass% or more , it can also be 0.1 mass% or more. Moreover, the concentration (content) of the layered compound in the polishing composition is preferably 5 mass% or less, more preferably 2 mass% or less. When it is within this range, the above-mentioned effects of the present invention can be obtained efficiently. The concentration (content) of the layered compound in the polishing composition may be 1% by mass or less or 0.5% by mass or less.

According to the above, the concentration (content) of the layered compound in the polishing composition is preferably 0.01 mass% or more and 5 mass% or less, more preferably 0.02 mass% or more and 2 mass% or less. In several aspects, the concentration (content) of the layered compound in the polishing composition may be 0.05 mass % or more and 1 mass % or more, 0.08 mass % or more and 0.5 mass % or less, or 0.1 mass % or more. 0.5% by mass or less.

Although not particularly limited, the concentration of the layered compound in the polishing composition (in the case where a plurality of types of layered compounds are included in the polishing composition) is used to better exert the effect of the layered compound in the polishing composition. The ratio (D/A) of the total concentration of equal amounts in the case of a compound) D [mass %] and the concentration of abrasive grains (the total concentration of equal amounts in the case of a plurality of abrasive grains) A [mass %] It is preferable to set it to 0.008 or more, and it is more preferable to set it to 0.01 or more. For example, it can set it to 0.03 or more, 0.04 or more, or 0.05 or more. D/A is not particularly limited, but it is preferably 5.0 or less, more preferably 2.0 or less, for example, it can be 1.0 or less, 0.5 or less, or 0.2 or less. According to the above, D/A is preferably 0.008 or more and 5.0 or less, preferably 0.01 or more and 2.0 or less. For example, it can be 0.03 or more and 1.0 or less, 0.04 or more and 0.5 or less, or 0.05 or more and 0.2 or less.

[dispersion medium] The polishing composition of the present invention contains a dispersion medium for dispersing each component. As the dispersion medium, water is preferred. From the viewpoint of suppressing the effects of inhibiting other components, it is preferable to use water that contains as little impurities as possible. Specifically, it is preferable to use pure water that removes impurity ions with an ion exchange resin and then passes through a filter to remove foreign matter. Or ultrapure water, or distilled water.

[PH value of grinding composition] The lower limit of the pH value of the polishing composition of the present invention is not particularly limited, but is preferably 1.0 or more. The pH value of the polishing composition may, for example, exceed 1.0, may be 1.5 or more, may exceed 1.5, or may be 2.0 or more. Moreover, the upper limit of the pH value is not particularly limited, but it is preferably 8.0 or less, more preferably less than 8.0, further preferably 7.0 or less, particularly preferably less than 7.0. From the perspective of improving the buffering effect of the metal salt A, the upper limit of the pH value may be 6.5 or less, or 6.0 or less. According to the above, the pH value of the polishing composition of the present invention can be more than 1.0 and less than 8.0, can be more than 1.0 and less than 8.0, can be more than 1.5 and less than 7.0, can be more than 1.5 but less than 7.0, can also be more than 2.0 and not more than 6.5 the following.

The pH value of the polishing composition can be adjusted by adding an acid or a salt thereof, or a base or a salt thereof described below.

[Other ingredients] If necessary, the polishing composition of the present invention may further contain an acid or a salt thereof or an alkali or a salt thereof for adjusting the pH value, a metal salt B other than the metal salt A, and a water-soluble salt that acts on the surface of the object to be polished or on the surface of the abrasive grains. Chemical polymers, anti-corrosion agents or chelating agents that inhibit corrosion of grinding objects, preservatives with other functions, antifungal agents and other ingredients.

As the acid, either an inorganic acid or an organic acid can be used. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid. Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, and 2-ethylbutyric acid. , 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid , glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furancarboxylic acid, 2,5-furandi Carboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, methanesulfonic acid, ethanesulfonic acid, sulfosuccinic acid, benzenesulfonic acid, toluene Sulfonic acid, phenylphosphonic acid, hydroxyethane-1,1-diphosphonic acid, etc. Furthermore, examples of salts include Group 1 element salts, Group 2 element salts, aluminum salts, ammonium salts, amine salts, and quaternary ammonium salts. These acids or their salts may be used alone or in combination of two or more. Among these, nitric acid and sulfuric acid are preferred.

The concentration (content) of the acid or its salt in the polishing composition can be appropriately adjusted so that the pH value falls within the above range.

Examples of the base or its salt include: amines such as aliphatic amines and aromatic amines; organic bases such as quaternary ammonium hydroxide; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; magnesium hydroxide, Hydroxides of Group 2 elements such as calcium hydroxide; and ammonia, etc.

The concentration (content) of the alkali or its salt in the polishing composition can be appropriately adjusted so that the pH value falls within the above-mentioned range.

Examples of the metal salt B include alkaline earth metal salts (salts of Group 2 elements). As the metal salt B, one alkaline earth metal salt may be used alone, or two or more alkaline earth metal salts may be used in combination. The metal salt B preferably contains any one or two or more of Mg, Ca, Sr, and Ba as elements belonging to alkaline earth metals. Among them, either Ca or Sr is preferred, and Ca is more preferred.

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 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 carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, glycine, butyric acid, citric acid, tartaric acid, and trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, and benzene. Salts of sulfonic acid, toluenesulfonic acid and other organic sulfonic acids, methylphosphonic acid, benzenephosphonic acid, toluenephosphonic acid and other organic phosphonic acids, ethylphosphoric acid and other organic phosphoric acids, etc.

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

Examples of water-soluble polymers include polycarboxylic acids such as polyacrylic acid, polysulfonic acids such as polyphosphonic acid and polystyrenesulfonic acid, polysaccharides such as xanthan gum and sodium alginate, and hydroxyethyl cellulose. , carboxymethyl cellulose and other cellulose derivatives, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, sorbitan monooleate, Oxyalkylene polymers having single or multiple oxyalkylene units. In addition, salts of the above compounds can also be suitably used as water-soluble polymers.

Examples of corrosion inhibitors include amines, pyridines, tetraphenylphosphonium salts, benzotriazoles, triazoles, tetrazoles, benzoic acid, and the like. Examples of the chelating agent include carboxylic acid-based chelating agents such as gluconic acid, amine-based chelating agents such as ethylenediamine, diethylenetriamine, and trimethyltetramine, ethylenediaminetetraacetic acid, and nitriloyl chelating agents. Triacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraminehexaacetic acid, diethylenetriaminepentaacetic acid and other polyamine polycarboxylic acid chelating agents, 2-aminoethylphosphonic acid, 1 -Hydroxyethylene-1,1-diphosphonic acid, aminotris(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid) ), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, methane hydroxyphosphonic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid and other organic Phosphonic acid chelating agents, phenol derivatives, 1,3-diketones, etc.

Examples of the preservative include sodium hypochlorite and the like. Examples of antifungal agents include oxazolines such as ethazolidine-2,5-dione.

[Grinding object] The object to be polished in the present invention is not particularly limited. For example, the object to be polished in the present invention is a substrate having a surface made of a semiconductor material, that is, a semiconductor substrate. Examples of materials constituting the semiconductor substrate include semiconductors containing Group 14 elements such as silicon and germanium; SiC, SiGe, ZnS, ZnSe, InP, AlN, GaAs, GaN, AlGaAs, InGaAs, GaP, ZnTe, CdTd and other compound semiconductors, etc. Among these, a compound semiconductor substrate is preferred, and a SiC (silicon carbide) substrate is more preferred.

Moreover, the material contained in the object to be polished in the present invention has a Vickers hardness of 500 Hv or more, for example. 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 contained in the object to be ground may be 1800 Hv or more, 2000 Hv or more, or 2200 Hv or more. The upper limit of the Vickers hardness of the material contained in the object to be polished is not particularly limited. For example, it may be about 7000 Hv or less, 5000 Hv or less, or 3000 Hv or less. In addition, in this specification, Vickers hardness can be measured based on JIS R 1610:2003. The international standard corresponding to the above JIS standard is ISO 14705:2000.

According to the above, the Vickers hardness of the material contained in the grinding object of the present invention may be 700 Hv or more and 7000 Hv or less, may be 1000 Hv or more and 5000 Hv or less, or may be 1500 Hv or more and 3000 Hv or less. In several aspects, the Vickers hardness of the material contained in the grinding object may be 1800 Hv or more and 3000 Hv or less, or may be 2000 Hv or more and 3000 Hv or less.

Examples of materials having a Vickers hardness of 1500 Hv or more include silicon carbide, silicon nitride, titanium nitride, gallium nitride, and the like. The object to be polished in the technology disclosed herein may be a single crystal surface having a mechanically and chemically stable material as described above. Among them, the surface of the object to be polished is preferably made of either silicon carbide or gallium nitride, and is more preferably made of silicon carbide. Silicon carbide is expected to be a compound semiconductor substrate material with low power loss and excellent heat resistance. It has a particularly great advantage in practical use in terms of improving productivity by increasing the polishing removal rate. The techniques disclosed herein are particularly well suited for grinding the surface of single crystals of silicon carbide.

[Production method of polishing composition] The manufacturing method of the polishing composition of the present invention is not particularly limited. For example, it can be obtained by stirring and mixing abrasive grains, oxidizing agent, metal salt A, layered compound, and other components as necessary in a dispersion medium.

The temperature when mixing each component is not particularly limited, but is preferably 10°C or more and 40°C or less. Heating may also be performed to increase the dissolution rate. In addition, the mixing time is not particularly limited.

From the viewpoint of promoting the formation of weak interaction between the layered compound and the abrasive particles, thereby further suppressing the sedimentation of the abrasive particles, and further improving the redispersibility of the abrasive particles, it is preferred that after producing the polishing composition of the present invention, This is stored at a predetermined temperature for a predetermined time, and the polishing composition after storage is used to polish a semiconductor substrate as a polishing object.

Specifically, the lower limit of the storage temperature is preferably 10°C or higher, more preferably 40°C or higher. In addition, the upper limit of the storage temperature is not particularly limited, but it is preferably 80°C or lower, more preferably 60°C or lower.

Furthermore, the lower limit of the storage time is preferably 20 days or more, and more preferably 60 days or more. In addition, there is no special limit on the upper limit of storage time.

[Grinding method] As described above, the polishing composition of the present invention can be suitably used for polishing semiconductor substrates.

When the polishing composition of the present invention is used to polish the object to be polished, the equipment or conditions used for ordinary polishing can be used. As a general polishing device, there is a single-side polishing device or a double-side polishing device. In the single-side polishing device, a holder called a template is used to hold the polishing object (preferably a substrate-shaped polishing object). ), while supplying the polishing composition, press the platen with the polishing cloth attached to one side of the object to be polished, and rotate the platen to polish one side of the object to be polished. In a double-sided polishing device, a holder called a carrier is used to hold the object to be polished. While supplying the polishing composition from above, a pressure plate with a polishing cloth attached is pressed against the opposite surface of the object to be polished. , causing them to rotate in opposite directions, thereby grinding both sides of the grinding object. At this time, polishing is performed by utilizing the physical action caused by the friction between the polishing pad and the polishing composition and the object to be polished, and the chemical action brought by the polishing composition to the object to be polished.

As a polishing pad used in the polishing method using the polishing composition of the present invention, for example, in addition to differences in materials such as polyurethane type, foamed polyurethane type, nonwoven type, and suede type, , there are also differences in physical properties such as hardness or thickness, and there are many kinds of polishing pads including polishing pads containing abrasive grains and polishing pads without abrasive grains, which can be used without restrictions.

When the polishing composition of the present invention is used to polish an object to be polished, the polishing composition once used for polishing can be recovered and used for polishing again. An example of a method of reusing the polishing composition is the following method: recovering the polishing composition discharged from the polishing device into a tank, and recycling it in the polishing device again. Recycling the polishing composition can reduce the environmental load by reducing the amount of the polishing composition discharged as waste liquid, and can suppress the damage to the polishing target by reducing the amount of the polishing composition used. Useful in terms of manufacturing cost of grinding.

When the polishing composition of the present invention is recycled, some or all of the abrasive grains, oxidants, metal salt A, layered compounds, and other additives consumed or lost due to polishing can be added as composition adjusters. In this case, as a composition adjuster, part or all of the abrasive grains, oxidizing agent, metal salt A, layered compound, and other additives may be mixed at any mixing ratio. By adding the composition adjuster in an additional manner, the polishing composition can be adjusted to a composition suitable for repeated use and polishing can be maintained well. The concentration of the abrasive grains, oxidizing agent, metal salt A, layered compound, and other additives contained in the composition adjuster is arbitrary and is not particularly limited, but is preferably appropriately adjusted according to the size of the circulation tank or grinding conditions.

The polishing composition of the present invention may be a one-liquid type or a multi-liquid type represented by a two-liquid type. Furthermore, the polishing composition of the present invention can be prepared by diluting the original solution of the polishing composition to, for example, 10 times or more using a diluent such as water.

The embodiments of the present invention have been described in detail, but they are illustrative and illustrative rather than restrictive. Obviously, the scope of the present invention should be interpreted by the appended patent claims.

The present invention includes the following aspects and forms. 1. A polishing composition, which contains abrasive grains, an oxidizing agent, a metal salt A, a layered compound, and a dispersion medium, and contains the above-mentioned metal salt A in an amount of 8 mM or more. The pKa of the above-mentioned metal salt A is a hydrated metal ion of less than 7.0. Salts of metal cations and anions; 2. The polishing composition as described in 1. above, wherein the layered compound is a layered silicate compound; 3. The polishing composition according to 1. or 2. above, wherein the average secondary particle size of the abrasive grains is 1.8 μm or less; 4. The polishing composition according to any one of 1. to 3. above, wherein the oxidizing agent is permanganic acid; 5. The polishing composition according to any one of 1. to 4. above, wherein the polishing composition is used for polishing a semiconductor substrate, and the semiconductor substrate is a compound semiconductor substrate; 6. A polishing method comprising the step of polishing a semiconductor substrate using the polishing composition according to any one of 1. to 5. above. [Example]

The present invention will be described in further detail using the following Examples and Comparative Examples. However, the technical scope of the present invention is not limited only to the following examples.

[Examples 1 to 10, Comparative Examples 1 to 3] (Preparation of grinding composition) The abrasive grains (average secondary particle diameter 0.4 μm) were diluted with water so that the concentration (content) would be 1.0% by mass, and the layered compound was added so that the concentration (content) was shown in Table 1 below, and then the layered compound was added to become The oxidizing agent and the metal salt A were added at the concentrations (contents) shown in Table 1 below, and stirred at room temperature (25°C) to obtain the polishing compositions of Examples 1 to 10 and Comparative Examples 1 to 3. . Furthermore, the pH value of the polishing composition of Examples 1 to 10 and Comparative Examples 2 to 3 was 3.7, and the pH value of the polishing composition of Comparative Example 1 was adjusted to 3.0 using nitric acid.

＜Abrasive grains＞ Alumina (alumina): The average secondary particle size was measured using a laser diffraction/scattering particle size distribution measuring device LA-950 manufactured by Horiba Manufacturing Co., Ltd.

＜Layered compound＞ Bentonite: particle size 0.15 μm Lithium bentonite: particle size 4.0 μm or 1.3 μm

In addition, the particle diameter of a layered compound is calculated|required by the following measurement. That is, 100 layered silicate compound particles were observed using a scanning electron microscope "SU8000" manufactured by Hitachi High-Technology Co., Ltd., and the smallest rectangle circumscribing the image of each particle was drawn. Then, the length of the long side of each rectangle drawn on the particle image was measured, and the average value was used as the particle diameter of the layered compound.

(Evaluation of anti-settling properties of abrasive grains) Use the polishing composition that has been stored at 25°C for 1 to 2 days after preparation. Put the polishing composition into a colorimetric tube (manufactured by AS ONE Co., Ltd.) with a capacity of 100 ml to the 100 ml mark. Let sit for 2 hours. After letting it stand, read the volume scale at the interface between the abrasive layer and the supernatant liquid, and make a judgment based on the following criteria. Evaluations A, B, and C are qualified: A: More than 40 ml B: More than 30 ml and less than 40 ml C: More than 20 ml and less than 30 ml D: 20 ml or less.

(Evaluation of redispersibility of abrasive grains) Use the polishing composition that has been stored at 25°C for 1 to 2 days after preparation. Put the polishing composition into a PP container (manufactured by AS ONE Co., Ltd.) with a capacity of 1000 ml to the 800 ml mark, and let it stand. 72 hours. After letting it stand, the PP container was shaken up and down to mix, and the number of times until the abrasive particles settled and dispersed again and disappeared was measured, and the judgment was made based on the following criteria. Evaluations A, B, and C are qualified: A: More than 1 time and less than 3 times B: More than 4 times and less than 6 times C: More than 7 times and less than 9 times D: More than 10 times.

(Evaluation of grinding) Using the polishing composition stored at 25° C. for 1 to 2 days after preparation, polishing was performed under the following polishing conditions, and the polishing removal rate was determined. In addition, the surface roughness of each polished object after polishing was measured by the following method:

<Grinding conditions> Grinding device: EJ-380IN (manufactured by Nippon Engis Co., Ltd.) Polishing pad: SUBA800 (manufactured by NITTA DuPont Co., Ltd.) Grinding load: 300 g/cm ² platen rotation speed: 80 rpm (80 min ^-1 ) Grinding time: 30 minutes

＜Grinding object＞ SiC substrate: 2-inch N type, 4H-SiC 4°off, Vickers hardness above 2000 Hv and below 2400 Hv.

＜Grinding removal speed＞ The grinding removal speed is calculated based on the difference in mass of the grinding object before and after grinding. The polishing removal speed obtained in each example is expressed as a relative value when the result of Comparative Example 1 is set to 100.

＜Surface roughness Ra＞ The surface roughness Ra of the polished object after polishing was measured using an atomic force microscope (NX-HDM manufactured by Park Systems). Furthermore, the surface roughness Ra is a parameter that represents the average amplitude of the height direction of the roughness curve, and represents the arithmetic average of the height of the surface of the polishing object within a certain field of view.

＜Storage stability＞ The storage stability of the polishing composition prepared above was evaluated by performing an accelerated test stored in an environment of 60°C. Specifically, the polishing composition of each example was filled into a transparent polyethylene resin container and sealed. The container was left still in an environment of 60°C, and the pH value of the polishing composition in the container was recorded until it increased. The number of days up to 2 days is considered as storage stability. Furthermore, in the accelerated test stored at 60°C, the storage stability was 19 days. By conversion based on Arenis' law, the storage stability is equivalent to approximately 12 months when stored at 25°C. The values shown in Table 1 below are the number of days in the accelerated test stored at 60°C.

The compositions and evaluation results of the polishing compositions of Examples 1 to 10 and Comparative Examples 1 to 3 are shown in Table 1 below. In addition, "-" in the following Table 1 means that the component was not added. [Table 1] abrasive grains oxidizing agent Metal salt A layered compounds Evaluation results Kind Concentration (mass %) Kind Concentration(mM) Kind Concentration(mM) Kind Particle size (μm) Concentration (mass %) Abrasive grain anti-settling properties Grinding grain redispersibility Grinding removal speed Surface roughness Ra (nm) Storage stability (days) Example 1 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 4.0 0.2 A A 125 0.06 twenty three Example 2 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Bentonite 0.15 0.2 A A 127 0.06 25 Example 3 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 1.3 0.1 B C 128 0.06 26 Example 4 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 8 Lithium bentonite 1.3 0.2 B B 126 0.06 12 Example 5 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 1.3 0.5 A A 125 0.06 twenty four Example 6 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 1.3 0.05 C C 128 0.06 25 Example 7 Alumina 1.0 sodium permanganate 1409 aluminum nitrate 30 Lithium bentonite 4.0 0.2 A A 181 0.06 twenty four Example 8 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 4.0 0.2 A A 105 0.06 25 Example 9 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 4.0 0.2 A A 122 0.06 twenty four Example 10 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 Lithium bentonite 4.0 0.2 A A 156 0.06 26 Comparative example 1 Alumina 1.0 Potassium permanganate 253 - - - - - D D 100 0.07 3 Comparative example 2 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 30 - - - D D 129 0.07 twenty four Comparative example 3 Alumina 1.0 Potassium permanganate 253 aluminum nitrate 4 Lithium bentonite 4.0 0.2 A A 122 0.06 8

It is clear from the above Table 1 that when the polishing composition of Examples containing a layered compound is used, good results can be obtained in terms of the anti-settling properties and redispersibility of the abrasive grains, and the polishing performance. In particular, compared with Comparative Example 1 in which no layered compound was added, it was found that the anti-settling properties and redispersibility of the abrasive grains were improved while maintaining the polishing performance such as the polishing removal rate and Ra. Furthermore, compared with Comparative Examples 2 and 3 in which other dispersants were used, it was found that the redispersibility of the abrasive grains was improved while maintaining the polishing performance such as the polishing removal rate and Ra.

This application is based on Japanese Patent Application No. 2022-118579 filed on July 26, 2022, and the entire disclosure is incorporated into this specification by reference.

Claims (6)

A polishing composition, which contains abrasive grains, an oxidizing agent, a metal salt A, a layered compound, and a dispersion medium, and contains the above-mentioned metal salt A in an amount of 8 mM or more, The above-mentioned metal salt A is a salt of a metal cation and anion whose pKa of the hydrated metal ion is less than 7.0. The polishing composition of claim 1, wherein the layered compound is a layered silicate compound. The polishing composition of claim 1 or 2, wherein the average secondary particle size of the above-mentioned abrasive grains is 1.8 μm or less. The polishing composition of claim 1 or 2, wherein the oxidizing agent is permanganic acid. The polishing composition according to claim 1 or 2, wherein the polishing composition is used for polishing a semiconductor substrate, and the semiconductor substrate is a compound semiconductor substrate. A polishing method, which includes the step of polishing a semiconductor substrate using the polishing composition of claim 1 or 2.