Polishing composition

Abstract

To provide a polishing composition that has improved redispersibility after alumina abrasive grains have settled and accumulated.SOLUTION: A polishing composition contains alumina abrasive grains and a redispersibility improving agent, wherein the redispersibility improving agent is a silicone compound having a hydrophilic group.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a polishing composition. [Background technology]

[0002] In chemical mechanical polishing of semiconductor wafers and semiconductor packages, alumina abrasive grains are sometimes used as high-hardness abrasive grains to increase the polishing rate. Alumina abrasive grains have a high specific gravity and tend to settle easily, and once the settled grains accumulate, they are difficult to redisperse. Therefore, they are often used without sufficient dispersion, which causes variations in polishing rate and wafer quality.

[0003] Japanese Patent Application Laid-Open No. 2021-195501 discloses a concentrated polishing composition containing alumina as abrasive grains, which has improved redispersibility. This concentrated polishing composition contains particulate alumina, colloidal alumina having an aspect ratio of greater than 5 and less than or equal to 800, a phosphorus-containing acid, and water, and has a pH of 2 to 4.5.

[0004] Japanese Patent Application Laid-Open Publication No. 2021-104547 discloses a polishing slurry used for polishing aluminum nitride polycrystalline substrates. This polishing slurry contains alumina abrasive grains and an anionic surfactant, and has a pH of 10 or higher. Japanese Patent Application Laid-Open Publication No. 2021-104547 also discloses a polishing slurry containing a silicone emulsion as an antifoaming agent. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-195501 [Patent Document 2] Patent Publication No. 2021-104547 Summary of the Invention [Problem to be solved by the invention]

[0006] JP 2021-195501 A describes a technique for improving the redispersibility of alumina abrasive grains by combining colloidal alumina with a phosphorus-containing acid. This technique requires a pH of 2 to 4.5, but a high pH does not provide sufficient electrostatic repulsion and prevents good redispersibility, limiting the applicable pH range.

[0007] An object of the present invention is to provide a polishing composition which has improved redispersibility after alumina abrasive grains have settled and accumulated. [Means for solving the problem]

[0008] A polishing composition according to one embodiment of the present invention comprises alumina abrasive grains and a redispersibility improver, and the redispersibility improver is a hydrophilic group-containing silicone compound. [Effects of the Invention]

[0009] According to the present invention, a polishing composition can be obtained which has improved redispersibility after the alumina abrasive grains have settled and accumulated. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a photograph of the appearance of a sample (before redispersion) that had been left standing at 50° C. for 30 days. [Figure 2] Figure 2 is a photograph of the appearance of the sample after redispersion. [Figure 3] Figure 3 is a photograph of the appearance of the redispersed sample when placed upside down. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present inventors have conducted various studies to solve the above problems. As a result, they have found that by blending a hydrophilic group-containing silicone compound as a redispersibility improver in a polishing composition containing alumina abrasive grains, the redispersibility of the alumina abrasive grains after they have settled and accumulated can be improved. The polishing composition according to one embodiment of the present invention will be described in detail below.

[0012] [Polishing composition] A polishing composition according to one embodiment of the present invention contains alumina abrasive grains and a redispersibility improver, and the redispersibility improver is a hydrophilic group-containing silicone compound.

[0013] [Alumina abrasive grains] The alumina abrasive grains are, for example, α-alumina abrasive grains, γ-alumina abrasive grains, δ-alumina abrasive grains, θ-alumina abrasive grains, η-alumina abrasive grains, κ-alumina abrasive grains, or χ-alumina abrasive grains. The abrasive grains of the polishing composition according to this embodiment are preferably α-alumina abrasive grains.

[0014] The particle size of the alumina abrasive grains is not limited to, but is, for example, 0.05 to 1.0 μm in median diameter. The lower limit of the median diameter of the alumina abrasive grains is preferably 0.1 μm. The upper limit of the median diameter of the alumina abrasive grains is preferably 0.8 μm.

[0015] The median diameter of alumina abrasive grains can be measured as follows. Specifically, a laser diffraction / scattering particle size distribution analyzer LA-920 (manufactured by Horiba, Ltd.) is used to determine the volumetric particle size distribution by laser diffraction / scattering. The particle size at which the cumulative volume frequency of the obtained volumetric particle size distribution is 50% is defined as the median diameter of the alumina abrasive grains.

[0016] The content of the alumina abrasive grains is, but is not limited to, for example, 0.1 to 5.0 wt %. The lower limit of the content of the alumina abrasive grains is preferably 0.5 wt %, more preferably 1.0 wt %. The upper limit of the content of the alumina abrasive grains is preferably 4.0 wt %, more preferably 3.0 wt %.

[0017] [Hydrophilic group-containing silicone compound] The polishing composition according to this embodiment contains a hydrophilic group-containing silicone compound as a redispersibility improver. Although the mechanism by which redispersibility is improved is not entirely clear, it is believed that the hydrophilic group-containing silicone compound adsorbs to the alumina abrasive grains, forming a layer of the hydrophilic group-containing silicone compound around the alumina abrasive grains, which inhibits aggregation of the alumina abrasive grains and improves redispersibility. In particular, since the surface of the alumina abrasive grains is hydrophilic, the hydrophilic groups of the hydrophilic group-containing silicone compound are oriented on the surface of the alumina abrasive grains, making them more easily adsorbed, and the resulting tight coating is thought to facilitate the development of the desired effect.

[0018] The hydrophilic group-containing silicone compound is a silicone (a polymer having a siloxane bond in the main skeleton) having a hydrophilic group. For example, the hydrophilic group-containing silicone compound is a compound in which a hydrophilic group is introduced into the main skeleton of polydimethylsiloxane. The hydrophilic group may be introduced into the terminal of the main chain of the polydimethylsiloxane (one or both terminals of the main chain), or into a part of the side chain.

[0019] The hydrophilic group is, but is not limited to, a group containing a hydroxy group, a sulfo group, a silanol group, an amino group, a carboxy group, or an ether group. The hydrophilic group is preferably a group containing an ether group, and more preferably a modified group containing a polyalkylene oxide. That is, the hydrophilic group-containing silicone compound is preferably a silicone compound having a modified group containing a polyalkylene oxide. Furthermore, the polyalkylene oxide contained in the modified group preferably contains polyethylene oxide (polyoxyethylene). Specifically, the polyalkylene oxide is preferably a molecular chain containing polyethylene oxide or a copolymer of ethylene oxide and propylene oxide.

[0020] The modified group containing polyalkylene oxide may have a terminal group other than a hydrogen atom. However, if a bulky hydrophobic group is present at the terminal of the modified group containing polyalkylene oxide, the hydrophilicity of the polyalkylene oxide may be impaired. Therefore, the modified group containing polyalkylene oxide is preferably one in which the terminal of the polyalkylene oxide is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms is added to the terminal of the polyalkylene oxide.

[0021] The number of moles of polyalkylene oxide added is not limited to, but is, for example, 5 to 50. The lower limit of the number of moles of polyalkylene oxide added is preferably 8. The upper limit of the number of moles of polyalkylene oxide added is preferably 40.

[0022] The hydrophilic group-containing silicone compound is preferably an ether-modified polydimethylsiloxane, and the modifying group is preferably a molecular chain containing polyethylene oxide or a copolymer of ethylene oxide and propylene oxide. The modifying group preferably has a terminal hydrogen atom or an alkyl group having 1 to 3 carbon atoms. The modifying group may be introduced into the terminal of the main chain of the polydimethylsiloxane (one terminal or both terminals of the main chain), or into a part of the side chain. The modifying group is preferably introduced into a part of the side chain.

[0023] Specific examples of hydrophilic group-containing silicone compounds include PEG-9 methyl ether dimethicone (a methyl ether of a polydimethylsiloxane derivative in which ethylene oxide (approximately 9 moles) is added to part of the side chain of polydimethylsiloxane), PEG-11 methyl ether dimethicone (a methyl ether of a polydimethylsiloxane derivative in which ethylene oxide (approximately 11 moles) is added to part of the side chain of polydimethylsiloxane), PEG-9 dimethicone (a polymer in which part of the methyl groups on the side chain of polydimethylsiloxane has been substituted with ethylene oxide (approximately 9 moles)), and PEG-10 dimethicone (a polymer in which part of the methyl groups on the side chain of polydimethylsiloxane has been substituted with ethylene oxide (approximately 10 moles)).

[0024] Two or more types of hydrophilic group-containing silicone compounds may be used in combination.

[0025] The content of the hydrophilic group-containing silicone compound (when two or more types are contained, the total amount; the same applies below) is, but is not limited to, 0.01 to 5.00 wt %. The lower limit of the content of the hydrophilic group-containing silicone compound is preferably 0.05 wt %, more preferably 0.10 wt %. The upper limit of the content of the hydrophilic group-containing silicone compound is preferably 2.00 wt %, more preferably 1.00 wt %, and even more preferably 0.50 wt %.

[0026] The content of the hydrophilic group-containing silicone compound may be 1 to 100 parts by weight per 100 parts by weight of the alumina abrasive grains. The lower limit of the content of the hydrophilic group-containing silicone compound is preferably 2 parts by weight, more preferably 5 parts by weight, and even more preferably 8 parts by weight per 100 parts by weight of the alumina abrasive grains. The upper limit of the content of the hydrophilic group-containing silicone compound is preferably 50 parts by weight, more preferably 20 parts by weight, and even more preferably 15 parts by weight per 100 parts by weight of the alumina abrasive grains.

[0027] [Phosphorus-containing acids] The polishing composition according to this embodiment may contain a phosphorus-containing acid as a second redispersibility improver. The inclusion of a phosphorus-containing acid further improves redispersibility. Although the mechanism behind this is not entirely clear, it is believed that the phosphorus-containing acid adsorbs to the alumina abrasive grains, changing the zeta potential of the alumina abrasive grains, resulting in a stabilizing effect due to electrostatic repulsion.

[0028] Specific examples of phosphorus-containing acids include phosphoric acid (orthophosphoric acid), pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, hexametaphosphoric acid, methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid (myo-inositol-1,2,3,4,5,6-hexaphosphate), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), nitrilotris ( Examples of suitable phosphorus-containing acids include ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethanehydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, and methanehydroxyphosphonic acid. The phosphorus-containing acid is preferably phosphoric acid. Two or more phosphorus-containing acids may be used in combination.

[0029] The content of the phosphorus-containing acid (when two or more types are contained, the total amount; the same applies below) is, but is not limited to, 0.0001 to 0.100% by weight. The lower limit of the content of the phosphorus-containing acid is preferably 0.0002% by weight, and more preferably 0.0005% by weight. The upper limit of the content of the phosphorus-containing acid is preferably 0.050% by weight, and more preferably 0.010% by weight, and even more preferably 0.005% by weight.

[0030] The content of the phosphorus-containing acid may be 0.01 to 5.0 parts by weight per 100 parts by weight of the alumina abrasive grains. The lower limit of the content of the phosphorus-containing acid is preferably 0.02 parts by weight, more preferably 0.03 parts by weight per 100 parts by weight of the alumina abrasive grains. The upper limit of the content of the phosphorus-containing acid is preferably 2.5 parts by weight, more preferably 0.50 parts by weight, and even more preferably 0.25 parts by weight per 100 parts by weight of the alumina abrasive grains.

[0031] [Surfactants] The polishing composition according to this embodiment may contain a surfactant. In this embodiment, any of anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants can be used as the surfactant. Two or more surfactants may be used in combination.

[0032] Examples of anionic surfactants include sulfonic acid-type anionic surfactants, sulfate ester-type anionic surfactants, carboxylic acid-type anionic surfactants, and phosphate ester-type surfactants. Examples of cationic surfactants include amine salt-type cationic surfactants and quaternary ammonium salt-type surfactants. Examples of nonionic surfactants include ester-type nonionic surfactants, ether-type nonionic surfactants, ester ether-type nonionic surfactants, alkanolamide-type nonionic surfactants, and alkylglycoxide-type nonionic surfactants. Examples of amphoteric surfactants include betaine-type amphoteric surfactants, sulfobetaine-type amphoteric surfactants, alkylbetaine-type amphoteric surfactants, amino acid-type amphoteric surfactants, and amine oxide-type amphoteric surfactants.

[0033] The surfactant is preferably an anionic surfactant or a nonionic surfactant. Particularly preferred anionic surfactants include alkylbenzenesulfonic acid and alkylbenzenesulfonate salts, specifically triethanolamine dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, etc. Particularly preferred nonionic surfactants include polyalkylene glycol derivatives, specifically polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycol, etc.

[0034] The content of surfactants (when two or more types are contained, the total amount; the same applies below) is, but is not limited to, 0.05 to 3.00 wt %. The lower limit of the surfactant content is preferably 0.10 wt %, more preferably 0.30 wt %. The upper limit of the surfactant content is preferably 2.00 wt %, more preferably 1.00 wt %, and even more preferably 0.80 wt %.

[0035] The surfactant content may be 5 to 100 parts by weight per 100 parts by weight of the alumina abrasive grains. The lower limit of the surfactant content is preferably 10 parts by weight, more preferably 20 parts by weight per 100 parts by weight of the alumina abrasive grains. The upper limit of the surfactant content is preferably 50 parts by weight, more preferably 30 parts by weight per 100 parts by weight of the alumina abrasive grains.

[0036] [Complexing agent] The polishing composition according to this embodiment may contain a complexing agent. A complexing agent is a compound containing an electron pair donor atom, and examples thereof include inorganic acids or salts thereof, organic acids or salts thereof, inorganic alkalis (such as ammonia) or salts thereof, amine compounds or salts thereof, nitrile compounds, and amino acids. Preferred complexing agents are amino acids and organic acids having a carboxyl group, with glycine, citric acid, and malonic acid being particularly preferred. Two or more complexing agents may be used in combination.

[0037] The content of the complexing agent (when two or more types are contained, the total amount; the same applies below) is, but is not limited to, 0.01 to 5.00 wt %. The lower limit of the content of the complexing agent is preferably 0.05 wt %, more preferably 0.10 wt %. The upper limit of the content of the complexing agent is preferably 3.00 wt %, more preferably 2.00 wt %, and even more preferably 1.60 wt %.

[0038] The content of the complexing agent may be 1 to 200 parts by weight per 100 parts by weight of the alumina abrasive grains. The lower limit of the content of the complexing agent is preferably 3 parts by weight, more preferably 5 parts by weight per 100 parts by weight of the alumina abrasive grains. The upper limit of the content of the complexing agent is preferably 100 parts by weight, more preferably 80 parts by weight per 100 parts by weight of the alumina abrasive grains.

[0039] [Other additives] The polishing composition of this embodiment may further contain, in addition to the above, general additives and compounding ingredients used in polishing compositions, such as a pH adjuster, a chelating agent, and a biocide (antiseptic).

[0040] [Dispersion medium] The dispersion medium of the polishing composition according to this embodiment is preferably water.

[0041] [pH] The pH of the polishing composition according to this embodiment is preferably 2.0 to 12.0. The polishing composition according to this embodiment has good redispersibility whether in the acidic or basic range. The pH of the polishing composition according to this embodiment may be, for example, more than 4.5 and not more than 12.0, or may be 5.0 to 12.0. The pH of the polishing composition according to this embodiment may be in the acidic range, for example, 2.0 to less than 7.0, or 2.0 to 6.0. The pH of the polishing composition according to this embodiment may be in the basic range, for example, more than 7.0 and not more than 12.0, or may be 8.0 to 12.0.

[0042] [Manufacturing method and usage] The polishing composition according to this embodiment is produced by mixing the above-mentioned alumina abrasive grains and the hydrophilic group-containing silicone compound, etc., and adding a dispersion medium. Alternatively, the polishing composition according to this embodiment is produced by sequentially mixing the above-mentioned alumina abrasive grains and the hydrophilic group-containing silicone compound, etc., with a dispersion medium. These components can be mixed by means commonly used in the technical field of polishing compositions, such as a homogenizer or ultrasonic waves.

[0043] The polishing composition according to this embodiment can be used for chemical mechanical polishing of semiconductor wafers or semiconductor packages. The polishing composition according to this embodiment can be used for polishing semiconductor wafers containing metal wiring such as copper, or semiconductor packages in which the semiconductor wafers are sealed with resin such as polyimide, although this is not limited thereto. The polishing composition according to this embodiment can be used for polishing at its original concentration, or can be used after diluting to an appropriate concentration.

[0044] The above describes a polishing composition according to one embodiment of the present invention. According to this embodiment, a polishing composition can be obtained that has improved redispersibility after the alumina abrasive grains have settled and accumulated. [Example]

[0045] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0046] [Experimental Example 1] Polishing compositions were prepared for Examples 1 to 6 and Comparative Examples 1 and 2 shown in Tables 1 and 2. The remainder of the components of the polishing composition (dispersion medium) was water.

[0047] The alumina abrasive grains used were α-alumina with a median diameter of 0.2 μm.

[0048] The following two types of silicone compositions were used:

[0049] The silicone composition "No. 1" in Tables 1 and 2 is a commercially available silicone emulsion (viscosity: 59.3 mPa·s at 25°C) used as an antifoaming agent. Nuclear magnetic resonance (NMR) analysis of this silicone composition revealed that it was a mixture of polydimethylsiloxane (hereinafter referred to as "PMDS") and a copolymer of ethylene oxide and propylene oxide (hereinafter referred to as "PEO-PPO"). However, no signals were observed due to bonds between PMDS and ethylene oxide or between PMDS and propylene oxide. This indicates that this silicone composition does not contain polydimethylsiloxane modified with polyethylene oxide or polydimethylsiloxane modified with a copolymer of ethylene oxide and propylene oxide (hereinafter collectively referred to as "PEO-PPO-PDMS").

[0050] The silicone composition "No. 2" in Tables 1 and 2 is a mixture of modified silicone oils (viscosity: 9100 mPa·s at 25°C) that is commercially available as a self-emulsifying antifoaming agent. NMR measurements revealed that this silicone composition contained PDMS:PEO-PPO:PEO-PPO-PDMS in a weight ratio of approximately 30:20:50. Furthermore, the average repeat numbers (average number of moles added) of PDMS, PPO, and PEO in PEO-PPO-PDMS were 8.4, 24, and 28, respectively.

[0051] The weight ratios and average repeat numbers of components in the silicone composition were determined as follows: The sample was fractionated with a solvent, and the weight ratios were calculated from the recovered amounts of each fraction using the formula below. However, since the solubility of PEO-PPO and PEO-PPO-PDMS in solvents is thought to vary depending on the molecular weight and combination of repeat units, this weight ratio is only a reference value. The hexane-insoluble portion was assumed to be entirely PEO-PPO-PDMS, and the average repeat number of each unit (PDMS, PPO, PEO) was calculated from the NMR measurement results. PDMS: Total weight - weight of methanol soluble part PEO-PPO: Weight of hexane soluble part - Weight of methanol soluble part PEO-PPO-PDMS: Total weight - Weight of hexane soluble part

[0052] After mixing the components, the pH was adjusted to the values ​​shown in Tables 1 and 2 using potassium hydroxide or nitric acid.

[0053] The redispersibility was evaluated as follows. 200 mL of each polishing composition was filled into a cylindrical transparent container (volume: 250 mL) measuring 13 cm in height and 6 cm in diameter. The container was sealed and allowed to stand at 50°C for 30 days. The height of the container was parallel to the vertical. After standing, it was confirmed that the abrasive grains had settled to the bottom of the container. The container was then placed on a shaker so that the height of the container was parallel to the horizontal, and subjected to rotational shaking at 120 rpm. Shaking was interrupted every minute until the shaking time was 10 minutes, and every two minutes thereafter. The container was visually observed, and the time until the sediment disappeared ("time required for redispersion" in Tables 1 and 2) was determined. The shaker used was an MMS-3010 manufactured by Tokyo Rikaki Co., Ltd.

[0054] [Table 1]

[0055] [Table 2]

[0056] As shown in Tables 1 and 2, the polishing compositions of Examples 1 to 6, which contained the silicone composition No. 2 containing PEO-PPO-PDMS, a hydrophilic group-containing silicone compound, required 10 minutes or less for redispersion, demonstrating good redispersibility. Furthermore, good redispersibility was obtained whether the solution was basic (Example 2, pH 8.8) or acidic (Examples 3 to 6, pH 2.7 to 4.9). Furthermore, good redispersibility was obtained whether a nonionic surfactant was used as the surfactant (Example 1), an anionic surfactant was used as the surfactant (Examples 2 and 3), or no surfactant was used (Examples 4 to 6). Furthermore, good redispersibility was obtained whether a complexing agent was used (Examples 1 to 3, 5, and 6) or no complexing agent was used (Example 4).

[0057] On the other hand, the polishing compositions of Comparative Example 1, which did not contain a silicone composition, and Comparative Example 2, which contained a silicone composition but did not contain a hydrophilic group-containing silicone compound, had inferior redispersibility compared to the polishing compositions of Examples 1 to 3.

[0058] [Experimental Example 2] Polishing compositions were prepared for Examples 7 to 13 and Comparative Examples 3 to 5 shown in Tables 3 and 4. The remainder of the components of the polishing composition (dispersion medium) was water.

[0059] The alumina abrasive grains used were α-alumina with a median diameter of 0.5 μm.

[0060] As the silicone compositions, in addition to the silicone compositions No. 1 and No. 2 shown in Tables 1 and 2, the following four types were also used.

[0061] The silicone composition "No. 3" in Tables 3 and 4 is a mixture of modified silicone oils (viscosity (25°C), 8000 mPa·s) commercially available as a self-emulsifying antifoaming agent. NMR measurement results showed that this silicone composition contained PDMS:PEO-PPO:PEO-PPO-PDMS in a weight ratio of approximately 50:20:30. The average repeat numbers (average number of moles added) of PDMS, PPO, and PEO were 9.9, 35, and 37, respectively.

[0062] The silicone composition "No. 4" in Tables 3 and 4 is a mixture of modified silicone oils (viscosity (25°C), 8000 mPa·s) that is commercially available as a self-emulsifying antifoaming agent. NMR measurement results showed that this silicone composition contained PDMS:PEO-PPO:PEO-PPO-PDMS in a weight ratio of approximately 30:7:60. The average repeat numbers (average number of moles added) of PDMS, PPO, and PEO were 7.5, 30, and 36, respectively.

[0063] The silicone compound "No. 5" in Tables 3 and 4 is a polyether-modified silicone oil (viscosity (25°C) 130 mm) consisting of PEG-11 methyl ether dimethicone. 2 / s).

[0064] The silicone compound "No. 6" in Tables 3 and 4 is a polyether-modified silicone oil (viscosity (25°C) 400 mm) consisting of PEG-10 dimethicone. 2 / s).

[0065] Some polishing compositions (Example 7) contained phosphoric acid as a second redispersibility improver.

[0066] Other than that, a polishing composition was prepared in the same manner as in Experimental Example 1, and redispersibility was evaluated in the same manner as in Example 1.

[0067] [Table 3]

[0068] [Table 4]

[0069] As shown in Tables 3 and 4, the polishing compositions of Examples 7 to 13, which contained any of silicone compositions Nos. 2 to 4 containing PEO-PPO-PDMS, a hydrophilic group-containing silicone compound, silicone composition No. 5 containing PEG-11 methyl ether dimethicone, and silicone composition No. 6 containing PEG-10 dimethicone, required 10 minutes or less for redispersion and exhibited good redispersibility. Furthermore, as shown in Example 13, good redispersibility was obtained even when no surfactant was contained.

[0070] Furthermore, a comparison between Example 7 and Example 8 shows that the redispersibility can be further improved by including phosphoric acid as the second redispersibility improver.

[0071] On the other hand, the polishing compositions of Comparative Example 3, which did not contain a silicone composition, and Comparative Examples 4 and 5, which contained a silicone composition but did not contain a hydrophilic group-containing silicone compound, had inferior redispersibility compared to the polishing compositions of Examples 7 to 13.

[0072] [Experimental Example 3] A more quantitative evaluation of redispersibility was carried out for some of the prepared polishing compositions by the method described below. The subjects selected for measurement were Example 8, which required a relatively long time for redispersion among Examples 1 to 13, and Comparative Examples 3 and 4, which were similar to Example 8 in terms of conditions other than the silicone composition.

[0073] As in the redispersibility evaluation tests in Experimental Examples 1 and 2, each polishing composition was left standing at 50°C for 30 days, and then subjected to rotary shaking at 120 rpm for 10 minutes to redisperse the alumina abrasive grains, to prepare a sample (hereinafter referred to as a "redispersed sample"). The shaking time was fixed at 10 minutes, regardless of whether the sediment disappeared or not. In the measurement of the solid content concentration and inorganic content concentration described below, the sediment was not included in the measurement target, and only the dispersion liquid was sampled and measured. For comparison, a sample that had been stored at room temperature after production (hereinafter referred to as a "completely dispersed sample") was used.

[0074] Fig. 1 is a photograph of the appearance of a sample (before redispersion) that had been left standing at 50°C for 30 days. Fig. 2 is a photograph of the appearance of the redispersed sample. Fig. 3 is a photograph of the appearance of the redispersed sample when placed upside down. Fig. 3 shows that in Comparative Examples 3 and 4, some of the alumina abrasive grains were not redispersed and adhered to the bottom of the container.

[0075] (Measurement of solids concentration) Approximately 4 g of each of the redispersed and completely dispersed samples was taken, placed in an aluminum dish, and heated at 115° C. for 90 minutes. The solids concentration of each of the redispersed and completely dispersed samples was calculated using the following formula from the change in weight before and after heating. Solid content concentration = ((weight of tare (aluminum dish) + weight of sample after heating) - weight of tare) / ((weight of tare + weight of sample before heating) - weight of tare) x 100

[0076] The difference in solid content between the redispersed sample and the completely dispersed sample, and the rate of change represented by the following formula were determined. Change rate of solids concentration = (solids concentration of redispersed sample - solids concentration of fully dispersed sample) / (solids concentration of fully dispersed sample) x 100

[0077] (Measurement of inorganic concentration) The samples used for measuring the solid content concentration were further heated for 40 minutes at 600° C. For each of the redispersed sample and the completely dispersed sample, the solid content concentration was calculated from the change in weight before and after heating using the following formula. Inorganic content = ((weight of tare (aluminum dish) + weight of sample after heating (after heating at 600°C)) - weight of tare) / ((weight of tare + weight of sample before heating (before heating at 115°C)) - weight of tare) x 100

[0078] The difference in inorganic component concentration between the redispersed sample and the completely dispersed sample, and the rate of change represented by the following formula were determined. Rate of change in inorganic concentration = (inorganic concentration of redispersed sample - inorganic concentration of fully dispersed sample) / (inorganic concentration of fully dispersed sample) x 100

[0079] The results are shown in Table 5.

[0080] [Table 5]

[0081] As shown in Table 5, in Example 8, the change rates for both the solid content concentration and the inorganic content concentration were 1.0% or less. In contrast, the change rates were 4.0% or more in Comparative Examples 3 and 4. A significant quantitative difference was observed between Example 8 and Comparative Examples 3 and 4.

[0082] The embodiments of the present invention have been described above. The above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and carried out within the scope of the invention.

Claims

1. Alumina abrasive grains, a redispersibility enhancer, The polishing composition, wherein the redispersibility improver is a hydrophilic group-containing silicone compound.

2. The polishing composition according to claim 1, the hydrophilic group-containing silicone compound is a silicone compound having a modifying group containing polyalkylene oxide, A polishing composition wherein the polyalkylene oxide comprises polyethylene oxide.

3. The polishing composition according to claim 2, A polishing composition wherein the hydrophilic group-containing silicone compound is an ether-modified polydimethylsiloxane, and the modifying group is a molecular chain containing polyethylene oxide or a copolymer of ethylene oxide and propylene oxide.

4. The polishing composition according to any one of claims 1 to 3, The polishing composition further comprises a complexing agent.

5. The polishing composition according to any one of claims 1 to 3, The polishing composition further comprises a surfactant.

6. The polishing composition according to claim 5, The polishing composition, wherein the surfactant is an anionic surfactant.

7. The polishing composition according to claim 5, The polishing composition, wherein the surfactant is a nonionic surfactant.

8. The polishing composition according to any one of claims 1 to 3, The polishing composition further comprises a phosphorus-containing acid.

9. The polishing composition according to any one of claims 1 to 3, A polishing composition having a pH of 2.0 to 12.0.

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