Polishing composition, concentrated solution of polishing composition, and polishing method

Abstract

This invention provides a means that is capable of improving the surface quality of a polished object after polishing.　This invention is a polishing composition used for polishing a surface made up of a silicon material, the polishing composition containing abrasive grains, a basic compound, a polyvinyl alcohol-based polymer, and polyhydric alcohol having a molecular weight of 600 or less.

Description

Polishing composition, concentrated polishing composition, and polishing method

[0001] The present invention relates to a polishing composition, a concentrated polishing composition, and a polishing method.

[0002] In order to realize high integration and high speed of integrated circuits such as ULSI used in computers, design rules for semiconductor devices are becoming finer year by year. As a result, there are increasing cases where even minute surface defects adversely affect the performance of semiconductor devices, and the importance of managing nano-order defects, which were not previously considered a problem, is increasing.

[0003] For example, Japanese Patent No. 6028942 (corresponding to the specification of U.S. Patent Application Publication No. 2015 / 0123027) discloses a polishing composition for wafers that contains water, silica particles, an alkali compound, polyvinyl alcohol, anion-modified polyvinyl alcohol, and a surfactant, and in which the mass ratio of the anion-modified polyvinyl alcohol to the polyvinyl alcohol is 0.6 to 5.5. This technology is said to be able to improve wafer haze.

[0004] However, the technology described in Japanese Patent No. 6028942 (corresponding to the specification of U.S. Patent Application Publication No. 2015 / 0123027) does not sufficiently improve the surface quality of the object to be polished after polishing, and further improvement is required.

[0005] Therefore, an object of the present invention is to provide a means capable of improving the surface quality of an object to be polished after polishing.

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by a polishing composition used for polishing the surface of a silicon material, the polishing composition comprising abrasive grains, a basic compound, a polyvinyl alcohol-based polymer, and a polyhydric alcohol having a molecular weight of 600 or less, thereby completing the present invention.

[0007] The present invention relates to a polishing composition used for polishing the surface of a silicon material, the polishing composition comprising abrasive grains, a basic compound, a polyvinyl alcohol-based polymer, and a polyhydric alcohol having a molecular weight of not more than 600. The polishing composition according to one embodiment of the present invention having such a configuration can improve the surface quality of an object to be polished after polishing.

[0008] The mechanism by which the polishing composition of the present invention provides the above-described effects is believed to be as follows: However, the following mechanism is merely speculation, and the scope of the present invention is not limited thereby.

[0009] After polishing, organic residues derived from abrasive grains, polishing pads, etc. are present on the surface of the object to be polished, and removing these residues as much as possible leads to improved surface quality. The polyhydric alcohol with a molecular weight of 600 or less used in the present invention is likely to adsorb to the surface of the object to be polished and the residues, but can be easily removed when cleaning the surface of the object to be polished after polishing. Therefore, it is believed that the residues on the surface of the object to be polished after polishing are removed together with the polyhydric alcohol, thereby improving the surface quality of the object to be polished after polishing.

[0010] While the present invention will be described below with reference to exemplary embodiments, it should be understood that the present invention is not limited to the following exemplary embodiments and can be modified in various ways within the scope of the claims. The exemplary embodiments described in this specification can be combined in any manner to form other exemplary embodiments.

[0011] In this specification, unless otherwise specified, operations and measurements of physical properties are carried out at room temperature (20° C. or higher and 25° C. or lower) and at a relative humidity of 40% RH or higher and 50% RH or lower.

[0012] [Abrasive Grains] The polishing composition according to some embodiments of the present invention contains abrasive grains. The abrasive grains mechanically polish the surface of the object to be polished. The material and properties of the abrasive grains are not particularly limited and can be appropriately selected depending on the intended use and manner of use of the polishing composition. Examples of abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include particles made of oxides such as silica, alumina, cerium oxide, chromium oxide, titanium dioxide, zirconium oxide, magnesium oxide, manganese dioxide, zinc oxide, and red iron oxide; particles made of nitrides such as silicon nitride and boron nitride particles; particles made of carbides such as silicon carbide and boron carbide; particles made of diamond; and carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles, poly(meth)acrylic acid particles (here, (meth)acrylic acid refers collectively to acrylic acid and methacrylic acid), and polyacrylonitrile particles. Such abrasive grains may be used alone or in combination of two or more.

[0013] The polishing composition according to some embodiments of the present invention preferably contains silica as an abrasive. Specific examples of silica include colloidal silica, fumed silica, precipitated silica, and the like. Silica can be used singly or in combination of two or more types. Colloidal silica is particularly preferred because it is less likely to scratch the surface of the object to be polished and can exhibit good polishing performance (such as the ability to reduce surface roughness). Examples of colloidal silica that can be preferably used include colloidal silica prepared by the ion exchange method using water glass (sodium silicate) as a raw material, and colloidal silica prepared by the alkoxide method (colloidal silica produced by the hydrolysis and condensation reaction of alkoxysilane). Colloidal silica can be used singly or in combination of two or more types.

[0014] The true specific gravity of silica is preferably 1.5 or more, more preferably 1.6 or more, and even more preferably 1.7 or more. The upper limit of the true specific gravity of silica is not particularly limited, but is typically 2.3 or less, for example, 2.2 or less. The true specific gravity of silica can be measured by a liquid substitution method using ethanol as a substitution liquid.

[0015] The shape of the abrasive grains such as colloidal silica is not particularly limited and may be spherical or non-spherical. Specific examples of non-spherical shapes include polygonal prisms such as triangular prisms and quadrangular prisms, cylinders, bale-shaped cylinders in which the center is bulged more than the ends, doughnut-shaped discs with a central hole, plate-shaped discs, cocoon-shaped discs with a central constriction, associative spheres in which multiple particles are integrated, confetti-shaped discs with multiple protrusions on the surface, and rugby ball-shaped discs, and are not particularly limited.

[0016] Although not particularly limited, the average value of the long axis / short axis ratio (average aspect ratio) of the abrasive grains is, in principle, 1.0 or more, preferably 1.05 or more, and more preferably 1.1 or more. By increasing the average aspect ratio, a higher polishing rate can be achieved. Furthermore, from the viewpoint of reducing scratches, etc., the average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less.

[0017] The shape (outer shape) and average aspect ratio of abrasive grains can be determined, for example, by observation with an electron microscope. A specific procedure for determining the average aspect ratio involves, for example, using a scanning electron microscope (SEM), drawing the smallest rectangle circumscribing each particle image for a predetermined number (e.g., 200) of silica particles whose individual particle shapes can be recognized. Then, for each rectangle drawn for each particle image, the long side length (long diameter value) is divided by the short side length (short diameter value) to calculate the long diameter / short diameter ratio (aspect ratio). The average aspect ratio can be determined by arithmetically averaging the aspect ratios of the predetermined number of particles.

[0018] The abrasive grains contained in the polishing composition may be in the form of primary particles, or may be in the form of secondary particles in which a plurality of primary particles are aggregated. Furthermore, abrasive grains in the form of primary particles and abrasive grains in the form of secondary particles may be mixed. In a preferred embodiment, at least a portion of the abrasive grains are contained in the polishing composition in the form of secondary particles.

[0019] Here, the surface of the object to be polished (especially silicon wafer) is generally polished to a high-quality mirror finish through a lapping process and a polishing process.The polishing process is usually composed of a plurality of polishing processes, including a preliminary polishing process (preliminary polishing process, a polishing process before the final polishing process) and a final polishing process (final polishing process).For example, in the stage of roughly polishing the object to be polished (especially silicon wafer) (e.g., preliminary polishing process), a polishing composition with high processing power (polishing power) is used, and in the stage of more delicate polishing (e.g., final polishing process), a polishing composition with low polishing power tends to be used.As such, the polishing composition used has different polishing properties required for each polishing process, so the particle size and content of silica contained in the polishing composition can be different depending on the stage of the polishing process in which the polishing composition is used.

[0020] In this case, an increase in the particle size of the abrasive grains tends to facilitate mechanical polishing of the surface of the object to be polished, and tends to improve the polishing rate, while a decrease in the particle size of the abrasive grains tends to facilitate reduction in haze on the polished object.

[0021] The average primary particle size of the abrasive grains contained in the polishing composition according to some embodiments of the present invention is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, and particularly preferably 20 nm or more (e.g., more than 20 nm).The average primary particle size of the abrasive grains contained in the polishing composition according to some embodiments of the present invention is, for example, 100 nm or less, may be 80 nm or less, preferably 60 nm or less, more preferably 50 nm or less, even more preferably 45 nm or less, and particularly preferably 43 nm or less.In some embodiments, the average primary particle size of the abrasive grains may be less than 40 nm, may be less than 38 nm, may be less than 35 nm, may be less than 32 nm, or may be less than 30 nm.

[0022] The average secondary particle size of the abrasive grains contained in the polishing composition according to some embodiments of the present invention is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 30 nm or more, and particularly preferably 35 nm or more. In some embodiments, the average secondary particle size of the abrasive grains may be 40 nm or more, 42 nm or more, or even 44 nm or more. In addition, the average secondary particle size of the abrasive grains contained in the polishing composition according to some embodiments of the present invention is, for example, 250 nm or less, 180 nm or less, or 150 nm or less, preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less. In some embodiments, the average secondary particle size of the abrasive grains may be 70 nm or less, 60 nm or less, or 50 nm or less.

[0023] The preferred ranges of the average primary particle size and average secondary particle size of the abrasive grains described above are also the preferred ranges of the average primary particle size and average secondary particle size of the abrasive grains contained in the raw material dispersion liquid used for the preparation thereof.

[0024] In this specification, the average primary particle diameter is calculated from the specific surface area (BET value) measured by the BET method by the following formula: average primary particle diameter (nm) = 6000 / (true density (g / cm ３ ) × BET value (m ２The specific surface area refers to the particle size (BET particle size) calculated by the formula: (1 / g) / (2 / g). The specific surface area can be measured, for example, using a "Flow Sorb II 2300" manufactured by Micromeritics. The average secondary particle size of the abrasive grains is measured, for example, by dynamic light scattering, for example, using a "Nanotrac (registered trademark) UPA-UT151" manufactured by Nikkiso Co., Ltd.

[0025] Furthermore, as mentioned above, since the polishing properties required of the polishing composition used differ for each polishing process, the content of abrasive grains in the polishing composition can also vary depending on the stage of the polishing process in which the polishing composition is used.

[0026] In this case, an increase in the content of abrasive grains tends to improve the polishing rate for the surface of the object to be polished, while a decrease in the content of abrasive grains tends to improve the dispersion stability of the polishing composition and reduce the amount of abrasive grain residue on the polished surface.

[0027] When the polishing composition according to some embodiments of the present invention is in the state of concentrated solution to be used for polishing by diluting with dispersion medium etc., the concentration (content) of abrasive grains is not particularly limited, but is preferably 0.001 mass% or more, more preferably 0.01 mass% or more, more preferably 0.025 mass% or more, even more preferably 0.1 mass% or more, particularly preferably 0.5 mass% or more, more particularly preferably 1 mass% or more, and most preferably 3 mass% or more, based on the total mass of the polishing composition.In addition, in this case, the concentration (content) of abrasive grains is not particularly limited, but from the viewpoint of storage stability, filterability etc., is preferably 50 mass% or less, more preferably 20 mass% or less, even more preferably 10 mass% or less, particularly preferably 9 mass% or less, based on the total mass of the polishing composition.

[0028] In addition, when the polishing composition according to some embodiments of the present invention is in the state of diluted solution, the concentration (content) of abrasive grains is not particularly limited, but from the viewpoint of further improving the polishing rate, it is preferably 0.001 mass% or more, more preferably 0.01 mass% or more, even more preferably 0.025 mass% or more, and particularly preferably 0.1 mass% or more, based on the total mass of the polishing composition.In addition, in this case, the concentration (content) of abrasive grains in the polishing composition is not particularly limited, but it is, for example, based on the total mass of the polishing composition, less than 10 mass%, may be less than 7 mass%, may be 5 mass% or less, may be 2 mass% or less, preferably less than 1 mass%, more preferably 0.8 mass% or less, more preferably 0.6 mass% or less, particularly preferably 0.4 mass% or less, and most preferably 0.3 mass% or less.

[0029] When two or more types of abrasive grains are used, the above concentration (content) refers to the total amount thereof.

[0030] When the above-mentioned polishing composition is used as a diluted solution, the preferred abrasive grain content is preferably adjusted by diluting a concentrated solution of the polishing composition with a dispersant such as water, or a solution or dispersion containing an optional polishing aid.

[0031] The polishing composition according to some embodiments of the present invention may contain colloidal silica and abrasive grains other than colloidal silica. However, when the polishing composition according to some embodiments of the present invention is in the form of a diluted solution, the content of the other abrasive grains is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on the total mass of the colloidal silica and the other abrasive grains. The most preferred embodiment is one in which the content of the other abrasive grains is 0% by mass, i.e., one in which no abrasive grains other than colloidal silica are contained.

[0032] [Basic Compound] The polishing composition of the present invention contains a basic compound. The basic compound refers to a compound that has the function of increasing the pH of water when added to water.

[0033] The type of basic compound is not particularly limited, and examples thereof include nitrogen-containing organic or inorganic basic compounds, hydroxides of alkali metals or alkaline earth metals (Group 2 metals), various carbonates and bicarbonates, quaternary ammonium hydroxides, quaternary ammonium salts, ammonia, amines, etc. Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of alkaline earth metal hydroxides include calcium hydroxide, strontium hydroxide, barium hydroxide, etc. Specific examples of carbonates or bicarbonates include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, etc. Specific examples of quaternary ammonium hydroxides or quaternary ammonium salts include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc. Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, and azoles such as imidazole and triazole.

[0034] From the viewpoint of reducing surface defects, the basic compound is preferably at least one selected from the group consisting of ammonia, quaternary ammonium hydroxide, quaternary ammonium salt, carbonate, hydrogen carbonate, and alkali metal hydroxide. Among these, at least one selected from the group consisting of ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, potassium hydroxide, and sodium hydroxide is more preferred, at least one selected from the group consisting of ammonia and tetramethylammonium hydroxide is even more preferred, and ammonia is particularly preferred. The basic compound may be used alone or in combination of two or more. Furthermore, the basic compound may be a commercially available product or a synthetic product.

[0035] When the polishing composition according to some embodiments of the present invention is in the form of a concentrated solution that is diluted with a dispersion medium or the like and used for polishing, the concentration (content) of the basic compound in the polishing composition is not particularly limited, but is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, even more preferably 0.01 mass% or more, and particularly preferably 0.05 mass% or more, based on the total mass of the polishing composition.In addition, in this case, the concentration (content) of the basic compound in the polishing composition is not particularly limited, but from the viewpoint of storage stability etc., is preferably 45 mass% or less, more preferably 15 mass% or less, even more preferably 5 mass% or less, and particularly preferably 1 mass% or less, based on the total mass of the polishing composition. That is, when the polishing composition is in the form of a concentrated liquid, the concentration (content) of the basic compound is preferably 0.001 mass% or more and 45 mass% or less, more preferably 0.005 mass% or more and 15 mass% or less, even more preferably 0.01 mass% or more and 5 mass% or less, and particularly preferably 0.05 mass% or more and 1 mass% or less, relative to the total mass of the polishing composition.

[0036] When the polishing composition according to some embodiments of the present invention is in the state of a diluted solution, the concentration (content) of the basic compound in the polishing composition is not particularly limited, but from the viewpoint of improving the polishing removal rate, etc., it is preferably 0.0001 mass% or more, more preferably 0.0005 mass% or more, even more preferably 0.001 mass% or more, even more preferably 0.002 mass% or more, and particularly preferably 0.003 mass% or more, based on the total mass of the polishing composition.In addition, in this case, from the viewpoint of improving surface quality, such as reducing defects, the concentration (content) of the basic compound in the polishing composition is preferably 15 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less, even more preferably 1 mass% or less, and particularly preferably 0.5 mass% or less, based on the total mass of the polishing composition. That is, when the polishing composition is in a diluted state, the concentration (content) of the basic compound is preferably 0.0001 mass% or more and 15 mass% or less, more preferably 0.0005 mass% or more and 10 mass% or less, even more preferably 0.001 mass% or more and 5 mass% or less, even more preferably 0.002 mass% or more and 1 mass% or less, and particularly preferably 0.003 mass% or more and 0.5 mass% or less, relative to the total mass of the polishing composition.

[0037] When two or more basic compounds are used, the above concentration (content) refers to the total amount thereof.

[0038] [Polyvinyl alcohol-based polymer] The polyvinyl alcohol-based polymer may contain only vinyl alcohol units (hereinafter also referred to as "VA units") as repeating units, or may contain VA units and repeating units other than VA units (hereinafter also referred to as "non-VA units"). The vinyl alcohol units are represented by the following chemical formula: -CH ２It is a structural moiety represented by -CH(OH)-. The polyvinyl alcohol-based polymer may be a random copolymer containing VA units and non-VA units, or may be a block copolymer, a graft copolymer, or an alternating copolymer. The polyvinyl alcohol-based polymer may contain only one type of non-VA unit, or may contain two or more types of non-VA units. In this specification, all water-soluble polymers containing VA units are classified as polyvinyl alcohol-based polymers.

[0039] The polyvinyl alcohol-based polymer used in the polishing composition disclosed herein may be unmodified polyvinyl alcohol (unmodified PVA) or modified polyvinyl alcohol (modified PVA). Here, unmodified PVA is a polymer produced by hydrolysis (saponification) of polyvinyl acetate, and has a repeating unit (-CH) structure in which vinyl acetate is vinyl-polymerized. ２ -CH(OCOCH ３ )-) and a polyvinyl alcohol-based polymer that is substantially free of repeating units other than VA units. The degree of saponification of the unmodified PVA may be, for example, 60% or more, and from the viewpoint of water solubility, may be 70% or more, 80% or more, or 90% or more. In some embodiments, unmodified PVA having a degree of saponification of 95% or more or 98% or more can be preferably used as the water-soluble polymer compound.

[0040] The polyvinyl alcohol-based polymer may be a modified PVA containing VA units and non-VA units having at least one structure selected from an oxyalkylene group, a carboxy group, a (di)carboxylic acid group, a (di)carboxylic acid ester group, a phenyl group, a naphthyl group, a sulfo group, an amino group, a hydroxy group, an amide group, an imide group, a nitrile group, an ether group, an ester group, and salts thereof.

[0041] Non-VA units that may be contained in the modified PVA include, but are not limited to, repeating units derived from N-vinyl monomers or N-(meth)acryloyl monomers, as described below, repeating units derived from ethylene, repeating units derived from alkyl vinyl ethers, repeating units derived from vinyl esters of monocarboxylic acids having 3 or more carbon atoms, and repeating units derived from (di)acetone compounds. A preferred example of the N-vinyl monomer is N-vinyl-2-pyrrolidone. A preferred example of the N-(meth)acryloyl monomer is N-(meth)acryloylmorpholine. The alkyl vinyl ether may be, for example, a vinyl ether having an alkyl group having 1 to 10 carbon atoms, such as propyl vinyl ether, butyl vinyl ether, or 2-ethylhexyl vinyl ether. The vinyl ester of a monocarboxylic acid having 3 or more carbon atoms may be, for example, a vinyl ester of a monocarboxylic acid having 3 to 7 carbon atoms, such as vinyl propanoate, vinyl butanoate, vinyl pentanoate, or vinyl hexanoate. Preferred examples of the (di)acetone compound include diacetone (meth)acrylamide and acetylacetone.

[0042] The polyvinyl alcohol-based polymer may be a modified PVA in which a portion of the VA units contained in the polyvinyl alcohol-based polymer is acetalized with an aldehyde compound or a ketone compound. In a preferred embodiment of the technology disclosed herein, the acetalized modified PVA is a water-soluble polymer obtained by an acetalization reaction between the above-mentioned non-modified PVA and an aldehyde compound.

[0043] In one embodiment of the present invention, the aldehyde compound used to produce the acetalized modified PVA is not particularly limited. In a preferred embodiment, the number of carbon atoms in the aldehyde compound is preferably 1 to 7, more preferably 2 to 7.

[0044] Examples of the aldehyde compound include formaldehyde; linear or branched alkyl aldehydes such as acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, tert-butyraldehyde, n-pentylaldehyde, and hexylaldehyde; and alicyclic or aromatic aldehydes such as cyclohexanecarbaldehyde and benzaldehyde. These may be used alone or in combination of two or more. With the exception of formaldehyde, the aldehyde compound may have one or more hydrogen atoms substituted with a halogen or the like. Among these, linear or branched alkyl aldehydes are preferred because of their high solubility in water and ease of acetalization reaction, and among these, acetaldehyde, propionaldehyde, n-butyraldehyde, and n-pentylaldehyde are more preferred.

[0045] In addition to the above, aldehyde compounds having 8 or more carbon atoms, such as 2-ethylhexylaldehyde, nonylaldehyde, and decylaldehyde, may also be used as the aldehyde compound. Furthermore, as the polyvinyl alcohol-based polymer, a cation-modified polyvinyl alcohol into which a cationic group such as a quaternary ammonium structure has been introduced may also be used. Examples of the cation-modified polyvinyl alcohol include those into which a cationic group derived from a monomer having a cationic group, such as a diallyldialkylammonium salt or an N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salt, has been introduced. Furthermore, as the polyvinyl alcohol-based polymer, a polyvinyl alcohol in which a non-VA unit is represented by the chemical formula: -CH ２ -CH(CR １ (OR ４ )-CR ２ (OR ５ )-R ３ )-, where R １ ~R ３ each independently represents a hydrogen atom or an organic group, R ４ and R ５ are each independently a hydrogen atom or R ６ -CO- (wherein, R ６represents an alkyl group). For example, R １ ~R ３ When at least one of R is an organic group, the organic group may be a linear or branched alkyl group having 1 to 8 carbon atoms. ６ can be a linear or branched alkyl group having from 1 to 8 carbon atoms.

[0046] In some embodiments, a modified PVA having a 1,2-diol structure in a side chain is used as the polyvinyl alcohol-based polymer. １ ~R ５ is a hydrogen atom (butenediol-vinyl alcohol copolymer (BVOH)).

[0047] The proportion of moles of VA units to the total number of moles of repeating units constituting the polyvinyl alcohol-based polymer may be, for example, 5% or more, 10% or more, 20% or more, or 30% or more. While not particularly limited, in some embodiments, the proportion of moles of VA units may be 50% or more, 65% or more, 75% or more, 80% or more, or 90% or more (e.g., 95% or more, or 98% or more). Substantially 100% of the repeating units constituting the polyvinyl alcohol-based polymer may be VA units. Here, "substantially 100%" means that the polyvinyl alcohol-based polymer does not, at least intentionally, contain non-VA units. Typically, the proportion of moles of non-VA units to the total number of moles of repeating units is less than 2% (e.g., less than 1%), including 0%. In some other embodiments, the ratio of the number of moles of VA units to the number of moles of all repeating units constituting the polyvinyl alcohol-based polymer may be, for example, 95% or less, 90% or less, 80% or less, or 70% or less.

[0048] The content of VA units in the polyvinyl alcohol-based polymer (content by mass) may be, for example, 5% by mass or more, 10% by mass or more, 20% by mass or more, or 30% by mass or more. While not particularly limited, in some embodiments, the content of VA units may be 50% by mass or more (e.g., more than 50% by mass), 70% by mass or more, or 80% by mass or more (e.g., 90% by mass or more, 95% by mass or more, or 98% by mass or more). Substantially 100% by mass of the repeating units constituting the polyvinyl alcohol-based polymer may be VA units. Here, "substantially 100% by mass" means that non-VA units are not, at least intentionally, contained as repeating units constituting the polyvinyl alcohol-based polymer, and typically means that the content of non-VA units in the polyvinyl alcohol-based polymer is less than 2% by mass (e.g., less than 1% by mass). In some other embodiments, the content of VA units in the polyvinyl alcohol-based polymer may be, for example, 95% by mass or less, 90% by mass or less, 80% by mass or less, or 70% by mass or less.

[0049] A polyvinyl alcohol-based polymer may contain multiple polymer chains with different VA unit contents within the same molecule. Here, the term "polymer chain" refers to a segment that constitutes a part of a single polymer molecule. For example, a polyvinyl alcohol-based polymer may contain, within the same molecule, a polymer chain A with a VA unit content of more than 50% by mass and a polymer chain B with a VA unit content of less than 50% by mass (i.e., a non-VA unit content of more than 50% by mass).

[0050] The polymer chain A may contain only VA units as repeating units, or may contain non-VA units in addition to VA units. The content of VA units in the polymer chain A may be 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. In some embodiments, the content of VA units in the polymer chain A may be 95% by mass or more, or 98% by mass or more. Substantially 100% by mass of the repeating units constituting the polymer chain A may be VA units.

[0051] Polymer chain B may contain only non-VA units as repeating units, or may contain VA units in addition to non-VA units. The content of non-VA units in polymer chain B may be 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. In some embodiments, the content of non-VA units in polymer chain B may be 95% by mass or more, or 98% by mass or more. Substantially 100% by mass of the repeating units constituting polymer chain B may be non-VA units.

[0052] Examples of polyvinyl alcohol-based polymers containing polymer chain A and polymer chain B in the same molecule include block copolymers and graft copolymers containing these polymer chains. The graft copolymer may be a graft copolymer having a structure in which polymer chain B (side chain) is grafted to polymer chain A (main chain), or a graft copolymer having a structure in which polymer chain A (side chain) is grafted to polymer chain B (main chain). In one embodiment, a polyvinyl alcohol-based polymer having a structure in which polymer chain B is grafted to polymer chain A can be used.

[0053] Examples of the polymer chain B include polymer chains having a repeating unit derived from an N-vinyl type monomer as the main repeating unit, polymer chains having a repeating unit derived from an N-(meth)acryloyl type monomer as the main repeating unit, polymer chains having a repeating unit derived from a vinyl dicarboxylate such as fumaric acid, maleic acid, or maleic anhydride as the main repeating unit, polymer chains having a repeating unit derived from an aromatic vinyl monomer such as styrene or vinylnaphthalene as the main repeating unit, and polymer chains having an oxyalkylene unit as the main repeating unit. In this specification, unless otherwise specified, the term "main repeating unit" refers to a repeating unit contained in an amount of more than 50% by mass.

[0054] A suitable example of the polymer chain B is a polymer chain having an N-vinyl monomer as the main repeating unit, i.e., an N-vinyl polymer chain. The content of repeating units derived from N-vinyl monomers in the N-vinyl polymer chain is typically more than 50% by mass, and may be 70% by mass or more, 85% by mass or more, or 95% by mass or more. Substantially all of the polymer chain B may be repeating units derived from N-vinyl monomers.

[0055] Examples of N-vinyl monomers include monomers having a nitrogen-containing heterocycle (e.g., a lactam ring) and N-vinyl chain amides. Specific examples of N-vinyl lactam monomers include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, 4-vinylmorpholin-3-one, N-vinyl-ε-caprolactam, N-vinyl-1,3-oxazin-2-one, and 4-vinyl-3,5-morpholinedione. Specific examples of N-vinyl chain amides include N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide. Polymer chain B may be, for example, an N-vinyl polymer chain in which more than 50% by mass (e.g., 70% by mass or more, 85% by mass or more, or 95% by mass or more) of its repeating units are N-vinyl-2-pyrrolidone units. Substantially all of the repeating units constituting polymer chain B may be N-vinylpyrrolidone units.

[0056] Other examples of polymer chain B include polymer chains whose main repeating units are repeating units derived from N-(meth)acryloyl-type monomers, i.e., N-(meth)acryloyl-based polymer chains. The content of repeating units derived from N-(meth)acryloyl-type monomers in the N-(meth)acryloyl-based polymer chain is typically more than 50% by mass, and may be 70% by mass or more, 85% by mass or more, or 95% by mass or more. Substantially all of polymer chain B may be repeating units derived from N-(meth)acryloyl-type monomers.

[0057] Examples of the N-(meth)acryloyl type monomer include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of linear amides having an N-(meth)acryloyl group include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-n-butyl(meth)acrylamide; and N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di(n-butyl)(meth)acrylamide. Examples of cyclic amides having an N-(meth)acryloyl group include N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine.

[0058] Another example of the polymer chain B is a polymer chain containing an oxyalkylene unit as the main repeating unit, i.e., an oxyalkylene-based polymer chain. The content of the oxyalkylene unit in the oxyalkylene-based polymer chain is typically more than 50% by mass, and may be 70% by mass or more, 85% by mass or more, or 95% by mass or more. Substantially all of the repeating units contained in the polymer chain B may be oxyalkylene units.

[0059] Examples of oxyalkylene units include oxyethylene units, oxypropylene units, oxybutylene units, etc. Such oxyalkylene units may be repeating units derived from the corresponding alkylene oxides. The oxyalkylene units contained in the oxyalkylene polymer chain may be of only one type, or may be of two or more types. For example, the oxyalkylene polymer chain may contain a combination of oxyethylene units and oxypropylene units. In an oxyalkylene polymer chain containing two or more types of oxyalkylene units, the oxyalkylene units may be a random copolymer of the corresponding alkylene oxides, or may be a block copolymer or a graft copolymer.

[0060] Further examples of polymer chain B include polymer chains containing repeating units derived from alkyl vinyl ethers (e.g., vinyl ethers having an alkyl group having from 1 to 10 carbon atoms), polymer chains containing repeating units derived from monocarboxylic acid vinyl esters (e.g., vinyl esters of monocarboxylic acids having from 3 or more carbon atoms), polymer chains in which some of the VA units have been acetalized with an aldehyde (e.g., alkylaldehydes having an alkyl group having from 1 to 7 carbon atoms), and polymer chains into which a cationic group (e.g., a cationic group having a quaternary ammonium structure) has been introduced.

[0061] As the polyvinyl alcohol-based polymer in the polishing composition of the present invention, non-modified PVA may be used, modified PVA may be used, or a combination of non-modified PVA and modified PVA may be used.In the embodiment in which non-modified PVA and modified PVA are used in combination, the amount of modified PVA used relative to the total amount of polyvinyl alcohol-based polymer contained in the polishing composition may be, for example, less than 95% by mass, may be 90% by mass or less, may be 75% by mass or less, may be 50% by mass or less, may be 30% by mass or less, may be 10% by mass or less, may be 5% by mass or less, or may be 1% by mass or less.The polishing composition of the present invention can be preferably implemented, for example, in an embodiment in which only one or two or more non-modified PVAs are used as the polyvinyl alcohol-based polymer.

[0062] Among these polyvinyl alcohol-based polymers, unmodified PVA, acetalized modified PVA, polyvinyl alcohol-polyvinylpyrrolidone copolymer, modified PVA containing oxyethylene units, and modified PVA containing repeating units derived from alkyl vinyl ether are more preferred.

[0063] According to some embodiments of the present invention, the weight average molecular weight of the polyvinyl alcohol-based polymer is 3×10 ３ It is preferable that the ratio is 4×10 or more. ３ More preferably, it is 5×10 or more. ３ According to some embodiments of the present invention, the weight-average molecular weight of the polyvinyl alcohol-based polymer is 100×10 or more. ４ It can be 50×10 ４ Less than 30 x 10 ４ Less than 20 × 10 ４ Less than 10 x 10 ４ Preferably, it is 9×10 or less. ４ More preferably, it is 8×10 or less. ４ It is more preferable that the weight average molecular weight of the polyvinyl alcohol-based polymer is equal to or less than 10 ...

[0064] When the polishing composition according to some embodiments of the present invention is in the form of a concentrated solution that is diluted with a dispersion medium or the like and used for polishing, the concentration (content) of polyvinyl alcohol polymer in the polishing composition is preferably 0.0001 mass% or more, more preferably 0.0005 mass% or more, even more preferably 0.001 mass% or more, particularly preferably 0.01 mass% or more, based on the total mass of the polishing composition, from the viewpoint of improving storage stability.In addition, in this case, the concentration (content) of polyvinyl alcohol polymer in the polishing composition is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, based on the total mass of the polishing composition, from the viewpoint of storage stability, filterability, etc. That is, when the polishing composition is in the form of a concentrated liquid, the concentration (content) of the polyvinyl alcohol-based polymer is preferably 0.0001 mass% or more and 5 mass% or less, more preferably 0.0005 mass% or more and 3 mass% or less, even more preferably 0.001 mass% or more and 1 mass% or less, and particularly preferably 0.01 mass% or more and 1 mass% or less, relative to the total mass of the polishing composition.

[0065] When the polishing composition according to some embodiments of the present invention is in the state of diluted solution, the concentration (content) of polyvinyl alcohol-based polymer in the polishing composition is preferably 0.00005 mass% or more, more preferably 0.0001 mass% or more, even more preferably 0.0005 mass% or more, particularly preferably 0.001 mass% or more, based on the total mass of the polishing composition, from the viewpoint of more excellent surface quality improvement effect.In addition, in this case, the concentration (content) of polyvinyl alcohol-based polymer is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, even more preferably 0.01 mass% or less, based on the total mass of the polishing composition, from the viewpoint of more excellent surface quality improvement effect. That is, when the polishing composition is in a diluted state, the concentration (content) of the polyvinyl alcohol-based polymer is preferably 0.00005 mass% or more and 0.1 mass% or less, more preferably 0.0001 mass% or more and 0.05 mass% or less, even more preferably 0.0005 mass% or more and 0.01 mass% or less, and particularly preferably 0.001 mass% or more and 0.01 mass% or less, relative to the total mass of the polishing composition.

[0066] When two or more kinds of polyvinyl alcohol-based polymers are used, the above concentration (content) refers to the total amount thereof.

[0067] [Polyhydric Alcohol with Molecular Weight of 600 or Less] The polyhydric alcohol according to the present invention is a compound containing two or more hydroxy groups per molecule. In some embodiments of the present invention, the molecular weight of the polyhydric alcohol is 600 or less. If the molecular weight exceeds 600, adsorption to the residue occurs, but the polyhydric alcohol tends to remain on the surface of the object to be polished after polishing, resulting in insufficient removal of the residue. Furthermore, when a monohydric alcohol is used, adsorption to the residue on the surface of the object to be polished is difficult, and the residue cannot be sufficiently removed. Note that, in this specification, the polyhydric alcohol does not include the above-mentioned polyvinyl alcohol-based polymer. Also, in this specification, the polyhydric alcohol does not include the block copolymer of ethylene oxide (EO) and propylene oxide (PO), which will be described later.

[0068] The lower limit of the molecular weight of the polyhydric alcohol is not particularly limited, but is usually 60 or more. The molecular weight of the polyhydric alcohol can be calculated from the molecular formula. If the nominal value of the molecular weight is disclosed by the manufacturer or the like, that nominal value can be used. According to some embodiments of the present invention, the molecular weight of the polyhydric alcohol is preferably 65 or more, more preferably 70 or more, and particularly preferably 75 or more. Furthermore, the molecular weight of the polyhydric alcohol is preferably 500 or less, more preferably 450 or less, and particularly preferably 400 or less. That is, the molecular weight of the polyhydric alcohol is preferably 65 or more and 500 or less, more preferably 70 or more and 450 or less, and particularly preferably 75 or more and 400 or less.

[0069] Specific examples of polyhydric alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,4-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6- Hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 2,2-dimethylolheptane, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol saturated aliphatic polyhydric alcohols such as cyclopentanediol, cyclopentane dimethanol, cyclopentane diethanol, cyclopentane dipropanol, cyclopentane dibutanol, cyclohexanediol, cyclohexane dimethanol, cyclohexane diethanol, cyclohexane dipropanol, cyclohexane dibutanol, cyclohexene diol, cyclohexene dimethanol, cyclohexene diethanol, cyclohexene dipropanol, cyclohexene dibutanol, cyclohexadiene diol, cyclohexadiene dimethanol, cyclohexadiene diethanol, cyclohexadiene dipropanol, cyclohexadiene dibutanol, hydrogenated bisphenol A, tricyclodecanediol, adamantyl diol, and spiroglycol; alicyclic polyhydric alcohols such as cyclopentanediol, cyclopentane dimethanol, cyclopentane diethanol, cyclopentane dipropanol, cyclopentane dibutanol, hydrogenated bisphenol A, tricyclodecanediol, adamantyl diol, and spiroglycol;Carbon-carbon double bond-containing polyhydric alcohols such as 2-butene-1,4-diol, 3-butene-1,4-diol, 2-pentene-1,5-diol, 3-hexene-1,6-diol, and 9-octadecene-7,12-diol; carbon-carbon double bond-containing polyhydric alcohols such as acetylene diol, propargyl alcohol, 2,5-dimethyl-3-hexyne-2,5-diol, 3,6-dimethyl-4-octyne-3,6-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,5-dimethyl-1-hexyne-3-ol, 3-methyl-1-butyne-3-ol, 3-methyl-1-pentyne-3-ol, 3-hexyne-2,5-diol, and 2-butyne-1,4-diol; Examples of suitable polyhydric alcohols include unsaturated aliphatic polyhydric alcohols such as triple bond-containing polyhydric alcohols (excluding compounds with alkylene oxides added thereto); aromatic ring-containing polyhydric alcohols such as 1,3-benzenedimethanol and 1,4-benzenedimethanol; sugar alcohols such as glycerin, threitol, erythritol, arabinitol, xylitol, sorbitol, iditol, galactitol, mannitol, volemitol, perseitol, D-erythro-D-galacto-octitol, quercitol, and inositol; and polyhydric alcohol polymers such as diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polyglycerin. These polyhydric alcohols can be used alone or in combination of two or more. Furthermore, commercially available polyhydric alcohols may be used, or synthetic products may be used. For example, commercially available carbon-carbon triple bond-containing polyhydric alcohols include Olfine (registered trademark) D-10 and Surfynol (registered trademark) 104 manufactured by Nissin Chemical Industry Co., Ltd.

[0070] Among these polyhydric alcohols, glycerin, polyglycerin, 1,2-propanediol, and unsaturated aliphatic polyhydric alcohols are preferred. Furthermore, among polyhydric alcohols, unsaturated aliphatic polyhydric alcohols are more preferred, polyhydric alcohol compounds containing a carbon-carbon triple bond (excluding compounds with alkylene oxide added) are even more preferred, and 2-butyne-1,4-diol is particularly preferred.

[0071] When the polishing composition according to some embodiments of the present invention is in the form of a concentrated solution that is diluted with a dispersion medium or the like and used for polishing, the concentration (content) of the polyhydric alcohol in the polishing composition is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, even more preferably 0.001% by mass or more, and particularly preferably 0.01% by mass or more, based on the total mass of the polishing composition, from the viewpoint of achieving a more excellent effect of improving surface quality.In addition, in this case, the concentration (content) of the polyhydric alcohol is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 1% by mass or less, based on the total mass of the polishing composition, from the viewpoint of achieving a more excellent effect of improving surface quality. That is, when the polishing composition is in the form of a concentrated liquid, the concentration (content) of the polyhydric alcohol in the polishing composition is preferably 0.0001 mass% or more and 5 mass% or less, more preferably 0.0005 mass% or more and 3 mass% or less, even more preferably 0.001 mass% or more and 1 mass% or less, and particularly preferably 0.01 mass% or more and 1 mass% or less, relative to the total mass of the polishing composition.

[0072] In some embodiments of the present invention, when the polishing composition is in the form of a diluted solution, the concentration (content) of the polyhydric alcohol in the polishing composition is preferably 0.00001 mass% or more, more preferably 0.00005 mass% or more, and even more preferably 0.0001 mass% or more, based on the total mass of the polishing composition, from the viewpoint of achieving a more excellent effect of improving surface quality.In addition, in this case, the concentration (content) of the polyhydric alcohol is preferably 0.1 mass% or less, more preferably 0.08 mass% or less, and even more preferably 0.06 mass% or less, based on the total mass of the polishing composition, from the viewpoint of achieving a more excellent effect of improving surface quality.That is, when the polishing composition is in the form of a diluted solution, the concentration (content) of the polyhydric alcohol in the polishing composition is preferably 0.00001 mass% or more and 0.1 mass% or less, more preferably 0.00005 mass% or more and 0.08 mass% or less, and even more preferably 0.0001 mass% or more and 0.06 mass% or less.

[0073] When two or more polyhydric alcohols are used, the above concentration (content) refers to the total amount thereof.

[0074] The polishing composition of the present invention may further contain a monohydric alcohol or a polyhydric alcohol having a molecular weight of more than 600, so long as it contains the above-mentioned polyhydric alcohol having a molecular weight of 600 or less.

[0075] [Water-soluble polymer] The polishing composition according to some embodiments of the present invention may further contain a water-soluble polymer (hereinafter also simply referred to as "water-soluble polymer") different from the polyvinyl alcohol-based polymer. The water-soluble polymer adheres to the surface of the object to be polished and protects the surface from uneven or excessive etching that may occur due to the action of the basic compound. This can further improve the quality of the surface of the object to be polished after polishing.

[0076] The water-soluble polymer may be any water-soluble polymer other than polyvinyl alcohol polymers (water-soluble polymers having VA units), and may have at least one functional group selected from the group consisting of cationic groups, anionic groups, and nonionic groups in the molecule. Examples include water-soluble polymers having anionic groups, water-soluble polymers having cationic groups, and water-soluble polymers having nonionic groups. In this specification, the term "anionic group" refers to a functional group that becomes an anion upon dissociation of a counter ion. The term "cationic group" refers to a functional group that becomes a cation upon dissociation of a counter ion or upon bonding with a cationic species generated by ionization of another ionic compound. The term "nonionic group" refers to a functional group that does not ionize.

[0077] The cationic group is not particularly limited, and examples thereof include an amino group or a salt thereof. Examples of water-soluble polymers having a cationic group include cationized cellulose, cationized guar gum, polydimethyldimethylenepyrrolidinium chloride, dimethyldimethylenepyrrolidinium chloride-(meth)acrylamide copolymer, (meth)acrylamide-(meth)acrylic acid-dimethyldiallylammonium chloride copolymer, N,N-dimethylaminoethyl diethyl(meth)acrylate sulfate, N,N-dimethyl polyethylene glycol(meth)acrylate, polyallylamine, glycidol-modified polyallylamine, and methyldiallylamine-sulfur dioxide copolymer.

[0078] Examples of the anionic group include a carboxy group, a sulfo group, a phosphate group, or a salt thereof.

[0079] Examples of water-soluble polymers having a carboxy group or a salt thereof (carboxy group-containing water-soluble polymers) include poly(meth)acrylic acid and derivatives thereof, and salts thereof.

[0080] Examples of polymers having a sulfo group or a salt group (sulfo group-containing water-soluble polymers) include sulfonic acid-modified polyvinyl alcohols (sulfonic acid group-containing polyvinyl alcohols, sulfonic acid group-containing modified polyvinyl alcohols), sulfonic acid group-containing polystyrenes such as polystyrene sulfonic acid (sulfonic acid group-containing modified polystyrenes), sulfonic acid-modified polyvinyl acetates (sulfonic acid group-containing polyvinyl acetates, sulfonic acid group-containing modified polyvinyl acetates), sulfonic acid group-containing polyesters (sulfonic acid group-containing modified polyesters), copolymers of (meth)acrylic acid-sulfonic acid group-containing monomers-sulfonic acid group-containing monomers such as copolymers of (meth)acrylic acid-sulfonic acid group-containing monomers, derivatives thereof, and salts thereof.

[0081] Phosphonic acid group (-P(=O)(OH) ２Examples of polymers having a group of a phosphonic acid group or a salt thereof (phosphonic acid group-containing water-soluble polymers) include (co)polymers containing structural units constituted by monomers such as 2-hydroxyethyl (meth)acryloyl phosphate and phenyl-2-acryloyloxyethyl phosphate, as well as derivatives thereof and salts thereof. Also included are (co)polymers containing structural units constituted by monomers such as (meth)acryloyloxymethyl phosphate, (meth)acryloyloxyethyl phosphate, (meth)acryloyloxypropyl phosphate, (meth)acryloyloxybutyl phosphate, (meth)acryloyloxypentyl phosphate, (meth)acryloyloxyhexyl phosphate, (meth)acryloyloxyoctyl phosphate, (meth)acryloyloxydecyl phosphate, (meth)acryloyloxylauryl phosphate, (meth)acryloyloxystearyl phosphate, and (meth)acryloyloxy-1,4-dimethylcyclohexyl phosphate, as well as derivatives thereof and salts thereof. Here, the term "(co)polymer" refers to a copolymer or a homopolymer. Examples of monomers constituting structural units of the copolymer other than the above structural units include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, 2,4-dimethylstyrene, ethylstyrene, phenylstyrene, cyclohexylstyrene, and benzylstyrene; hydroxy group-containing vinyl monomers such as hydroxystyrene, N-methylol(meth)acrylamide, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, polyethylene glycol mono(meth)acrylate, and 2-hydroxyethylpropenyl ether; and alkyl(meth)acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, dodecyl(meth)acrylate, hexadecyl(meth)acrylate, and eicosyl(meth)acrylate. In this specification, "having a phosphonic acid group or a salt thereof" means that the compound has a phosphonic acid group (-P(=O)(OH) ２) or a salt thereof, for example, a phosphonic acid group or a salt thereof may have a partial structure represented by a phosphate group (—O—P(═O)(OH) ２ ) or a salt thereof.

[0082] Examples of water-soluble polymers having a nonionic group include compounds containing, in the molecule, a hydroxy group, an acyloxy group, a sulfo group, a vinyl structure, a polyoxyalkylene structure, a heterocyclic structure, an amide structure, an imide structure, etc. Examples of water-soluble polymers having a nonionic group include cellulose derivatives, starch derivatives, and nitrogen atom-containing polymers.

[0083] The cellulose derivative refers to a cellulose in which some of the hydroxy groups of the cellulose are substituted with other different substituents. Examples of the cellulose derivative include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose.

[0084] Starch derivatives refer to starch or starch in which some of the hydroxyl groups have been substituted with other different substituents, such as pullulan.

[0085] Examples of nitrogen-containing polymers include polymers containing N-vinyl monomer units; polymers containing N-(meth)acryloyl monomer units; and the like. Examples of N-vinyl polymers include polymers containing repeating units derived from monomers having a nitrogen-containing heterocycle (e.g., a lactam ring). Examples of such polymers include homopolymers and copolymers of N-vinyl lactam monomers (e.g., copolymers in which the copolymerization ratio of N-vinyl lactam monomers exceeds 50% by mass), homopolymers and copolymers of N-vinyl linear amides (e.g., copolymers in which the copolymerization ratio of N-vinyl linear amides exceeds 50% by mass), and the like. Specific examples of N-vinyl lactam monomers (i.e., compounds having a lactam structure and an N-vinyl group in one molecule) include N-vinyl-2-pyrrolidone (VP), N-vinyl-2-piperidone, 4-vinyl-3-morpholin-3-one, N-vinyl-ε-caprolactam (VC), N-vinyl-1,3-oxazin-2-one, and 4-vinyl-3,5-morpholinedione. Specific examples of polymers containing N-vinyl lactam monomer units include polyvinylpyrrolidone, polyvinylcaprolactam, random copolymers of VP and VC, random copolymers of one or both of VP and VC with other vinyl monomers (e.g., acrylic monomers, vinyl ester monomers, etc.), block copolymers, alternating copolymers, and graft copolymers containing polymer chains containing one or both of VP and VC. Specific examples of N-vinyl linear amides include N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide.

[0086] Examples of N-(meth)acryloyl type polymers include homopolymers and copolymers of N-(meth)acryloyl type monomers (typically copolymers in which the copolymerization ratio of N-(meth)acryloyl type monomers exceeds 50 mass %). Examples of N-(meth)acryloyl type monomers include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of chain amides having an N-(meth)acryloyl group include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-n-butyl(meth)acrylamide; and N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di(n-butyl)(meth)acrylamide. Examples of polymers containing a chain amide having an N-(meth)acryloyl group as a monomer unit include homopolymers of N-isopropylacrylamide and copolymers of N-isopropylacrylamide (for example, copolymers in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by mass).

[0087] Examples of cyclic amides having an N-(meth)acryloyl group include N-acryloylmorpholine, N-acryloylthiomorpholine, N-acryloylpiperidine, N-acryloylpyrrolidine, N-methacryloylmorpholine, N-methacryloylpiperidine, and N-methacryloylpyrrolidine. Examples of polymers containing cyclic amides having an N-(meth)acryloyl group as a monomer unit include acryloylmorpholine-based polymers. Typical examples of acryloylmorpholine-based polymers include homopolymers of N-acryloylmorpholine (ACMO) (poly N-acryloylmorpholine (PACMO)) and copolymers of ACMO (for example, copolymers in which the copolymerization ratio of ACMO exceeds 50% by mass). In the acryloylmorpholine-based polymer, the proportion of the number of moles of ACMO units in the number of moles of all repeating units is usually 50% or more, and suitably 80% or more (e.g., 90% or more, typically 95% or more). All repeating units of the water-soluble polymer may be substantially composed of ACMO units.

[0088] When the water-soluble polymer is in the form of a salt, examples of the salt include, but are not particularly limited to, alkali metal salts such as sodium salts and potassium salts, salts of Group 2 elements such as calcium salts and magnesium salts, amine salts, and ammonium salts.

[0089] The weight average molecular weight (Mw) of the water-soluble polymer is, for example, about 200×10 ４ or less, and may be approximately 150×10 ４ From the viewpoint of cleaning properties, it is preferable to use a value of about 100×10 ４ is approximately 50×10 ４ From the viewpoint of protecting the polishing surface, the Mw of the water-soluble polymer may be, for example, 0.5 × 10 ４ In some embodiments, the Mw is 1.0×10 or more. ４ The above is appropriate, and 1.5 x 10 ４ or more, and may be 2×10 ４ or more, for example, 5×10 ４ More than 10 x 10 ４ More than that is fine.

[0090] The Mw of the water-soluble polymer can be the weight-average molecular weight calculated from a value based on gel permeation chromatography (GPC) (water system, polyethylene oxide equivalent). The measurement conditions for GPC can be the measurement conditions described in the Examples below.

[0091] The water-soluble polymer may be used alone or in combination of two or more kinds. In addition, the water-soluble polymer may be a commercially available product or a synthetic product.

[0092] As the water-soluble polymer, a homopolymer of N-acryloylmorpholine (ACMO) (poly N-acryloylmorpholine (PACMO)) is more preferred, from the viewpoint of better exerting the desired effects of the present invention.

[0093] When the polishing composition according to some embodiments of the present invention is in the form of a concentrated solution that is diluted with a dispersion medium or the like and used for polishing, the content (concentration) of water-soluble polymer in the concentrated solution is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.005% by mass or more, and even more preferably 0.01% by mass or more.In addition, in this case, the content (concentration) of water-soluble polymer in the concentrated solution of the polishing composition is not particularly limited, but from the viewpoint of storage stability etc., it is preferably 15% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.That is, when the polishing composition is in the form of a concentrated solution, the content (concentration) of water-soluble polymer is preferably 0.001% by mass or more and 15% by mass or less, more preferably 0.005% by mass or more and 5% by mass or less, and even more preferably 0.01% by mass or more and 3% by mass or less.

[0094] When the polishing composition according to some embodiments of the present invention is in the state of a diluted solution, the concentration (content) of the water-soluble polymer in the polishing composition is preferably 0.0001 mass% or more, more preferably 0.0003 mass% or more, even more preferably 0.0005 mass% or more, particularly preferably 0.001 mass% or more, and most preferably 0.003 mass% or more, based on the total mass of the polishing composition.In addition, in this case, the upper limit of the concentration (content) of the water-soluble polymer in the polishing composition is preferably 5 mass% or less, more preferably 1 mass% or less, even more preferably 0.5 mass% or less, even more preferably 0.2 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0.05 mass% or less, based on the total mass of the polishing composition. That is, when the polishing composition is in the state of a diluted solution, the concentration (content) of the water-soluble polymer is preferably 0.0001% by mass or more and 5% by mass or less, more preferably 0.0003% by mass or more and 1% by mass or less, even more preferably 0.0005% by mass or more and 0.5% by mass or less, even more preferably 0.001% by mass or more and 0.2% by mass or less, and particularly preferably 0.003% by mass or more and 0.1% by mass or less. When the polishing composition is in the state of a diluted solution, the concentration (content) of the water-soluble polymer in the polishing composition may be 0.001% by mass or more and 0.05% by mass or less, or may be 0.003% by mass or more and 0.05% by mass or less.

[0095] When two or more water-soluble polymers are used, the above concentration (content) refers to the total amount thereof.

[0096] [Dispersion Medium] In some embodiments of the present invention, the polishing composition preferably contains a dispersion medium for dispersing each component. The dispersion medium (particularly water) has the function of dissolving or dispersing the components contained in the polishing composition.

[0097] The dispersion medium may be a mixed solvent of water and an organic solvent for dispersing or dissolving each component. In this case, examples of the organic solvent used include water-miscible organic solvents such as acetone, acetonitrile, ethanol, methanol, isopropanol, glycerin, ethylene glycol, and propylene glycol. Alternatively, these organic solvents may be used without mixing with water, and the components may be dispersed or dissolved therein, followed by mixing with water. These organic solvents may be used alone or in combination. According to a preferred embodiment of the present invention, the dispersion medium contains water. According to a more preferred embodiment of the present invention, the dispersion medium consists essentially of water. Note that the term "substantially" as used above means that a dispersion medium other than water may be included, as long as the effects of the present invention can be achieved. More specifically, the dispersion medium preferably consists of 90% to 100% by mass of water and 0% to 10% by mass of a dispersion medium other than water, and more preferably 99% to 100% by mass of water and 0% to 1% by mass of a dispersion medium other than water. According to the most preferred embodiment of the present invention, the dispersion medium consists solely of water.

[0098] It is preferable that the water contains as few impurities as possible to prevent contamination of the polishing object or inhibition of the action of other components. For example, a water having a total transition metal ion content of 100 ppb or less is preferable. The purity of the water can be increased by, for example, removing impurity ions using an ion exchange resin, removing foreign matter using a filter, or by distillation. Specifically, it is preferable to use, for example, deionized water (ion-exchanged water), pure water, ultrapure water, distilled water, etc.

[0099] [Surfactant] The polishing composition of the present invention may contain a surfactant, if necessary. By incorporating a surfactant into the polishing composition, haze on the surface of the object to be polished after polishing can be more effectively reduced. Any of anionic, cationic, nonionic, and amphoteric surfactants can be used as the surfactant. Typically, anionic or nonionic surfactants are preferred. Nonionic surfactants are more preferred from the viewpoints of low foaming and ease of pH adjustment. Examples of nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyalkylene adducts); and copolymers of multiple oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). The surfactant preferably includes a surfactant containing a polyoxyalkylene structure. The surfactants may be used singly or in combination of two or more.

[0100] Specific examples of nonionic surfactants containing a polyoxyalkylene structure include block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO (polyethylene oxide)-PPO (polypropylene oxide)-PEO type triblock copolymers, PPO-PEO-PPO type triblock copolymers, etc.), random copolymers of EO and PO, polyoxyethylene glycol, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, Examples of the hydroxypropyl ether include polyoxyethylene oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopaltimate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil.Among these, preferred surfactants include block copolymers of EO and PO (particularly, PEO-PPO-PEO type triblock copolymers), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (for example, polyoxyethylene decyl ether).

[0101] The weight-average molecular weight (Mws) of the surfactant is typically less than 5,000, and is preferably 4,000 or less (e.g., 3,000 or less) from the viewpoint of filterability, cleanability, etc. Furthermore, from the viewpoint of surface activity, etc., the Mws of the surfactant is usually suitably 200 or more, and from the viewpoint of haze reduction effect, etc., it is preferably 250 or more (e.g., 300 or more). A more preferred range of the Mws of the surfactant may vary depending on the type of surfactant. For example, when a polyoxyethylene alkyl ether is used as the surfactant, its Mws is preferably 1,500 or less, and may be 1,000 or less (e.g., 500 or less). The Mws of the surfactant can be a molecular weight calculated from a value based on gel permeation chromatography (GPC) (aqueous, polyethylene oxide equivalent) or a molecular weight calculated from the chemical formula. The GPC measurement conditions can be the same as those for the water-soluble polymer described above.

[0102] When the polishing composition of the present invention contains a surfactant, its content is not particularly limited as long as it is within a range that does not significantly impair the effects of the present invention.Usually, from the viewpoint of cleaning properties, etc., it is appropriate that the content of surfactant per 100 parts by mass of abrasive grains is 20 parts by mass or less, preferably 15 parts by mass or less, and more preferably 10 parts by mass or less (for example, 8 parts by mass or less).From the viewpoint of better exerting the effect of using the surfactant, it is appropriate that the content of surfactant per 100 parts by mass of abrasive grains is 0.001 parts by mass or more, preferably 0.005 parts by mass or more, and may be 0.01 parts by mass or more, or may be 0.05 parts by mass or more.In addition, when two or more surfactants are used, the above content refers to their total amount.

[0103] [Other Components] The polishing composition of the present invention may further contain known additives that can be used in polishing compositions, such as chelating agents (complexing agents), pH adjusters, and antifungal agents (preservatives), within the range that does not impair the effects of the present invention. Hereinafter, the chelating agents, pH adjusters, and antifungal agents (preservatives) will be described. In addition, the oxidizing agent will also be described.

[0104] (Chelating Agent) The chelating agent captures metal impurity components in the polishing system to form a complex, thereby suppressing metal contamination on the surface of the object to be polished. The polishing composition according to one embodiment of the present invention may further contain a chelating agent.

[0105] Specific examples of the chelating agent include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Specific examples of the aminocarboxylic acid chelating agent include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid, sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, and sodium triethylenetetraminehexaacetate. Specific examples of organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, and α-methylphosphonosuccinic acid. Among these chelating agents, it is preferable to use an organic phosphonic acid chelating agent, in particular ethylenediaminetetrakis(methylenephosphonic acid). The chelating agents may be used alone or in combination of two or more.

[0106] (pH adjuster) In the polishing composition of the present invention, pH can be adjusted by each component described above, but pH adjuster can also be used to adjust to desired pH.Therefore, the polishing composition of the present invention may further contain a pH adjuster.As the pH adjuster, compounds other than the basic compounds described above can be mentioned, for example, inorganic acids, organic acids, etc.These can be used alone or in combination of two or more.

[0107] Specific examples of inorganic acids that can be used as pH adjusters include hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid. Among these, hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid are preferred, and nitric acid is more preferred.

[0108] Specific examples of organic acids that can be used as pH adjusters include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 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-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, methanesulfonic acid, ethanesulfonic acid, 10-camphorsulfonic acid, and isethionic acid.

[0109] As the pH adjuster, salts such as alkali metal salts of inorganic or organic acids may be used instead of or in combination with inorganic or organic acids. In the case of combinations of a weak acid and a strong base, a strong acid and a weak base, or a weak acid and a weak base, a pH buffering effect can be expected.

[0110] <pH of Polishing Composition> The pH of the polishing composition according to some embodiments of the present invention is preferably 7.0 or more, more preferably 7.5 or more, even more preferably 8.0 or more, particularly preferably 8.5 or more, and most preferably 9.0 or more. The pH of the polishing composition is preferably 12.5 or less, more preferably 12.0 or less, even more preferably 11.5 or less, particularly preferably 11.0 or less, and most preferably 10.5 or less. That is, the pH of the polishing composition is preferably 7.0 or more and 12.5 or less, more preferably 7.5 or more and 12.0 or less, even more preferably 8.0 or more and 11.5 or less, particularly preferably 8.5 or more and 11.0 or less, and most preferably 9.0 or more and 10.5 or less. In one embodiment, the pH of the polishing composition is 9.5 or more and 11.0 or less. When the pH of the polishing composition is within this range, the polyhydric alcohol acts more effectively on the surface of the object to be polished, thereby further improving the surface quality of the object to be polished.

[0111] The concentration (content) of the pH adjuster can be appropriately adjusted within the range in which the effects of the present invention are exhibited. The pH of the polishing composition can be measured, for example, with a pH meter (for example, a pH meter (model number: LAQUA) manufactured by Horiba, Ltd.).

[0112] (Antifungal Agent (Antiseptic)) The type of antifungal agent (antifungal agent) is not particularly limited and can be appropriately selected depending on the desired use and purpose. Specific examples include isothiazoline-based preservatives such as 1,2-benzisothiazol-3(2H)-one (BIT), 2-methyl-4-isothiazolin-3-one, and 5-chloro-2-methyl-4-isothiazolin-3-one, as well as phenoxyethanol.

[0113] (Oxidizing Agent) The polishing composition according to some embodiments of the present invention preferably does not substantially contain an oxidizing agent. If an oxidizing agent is contained in the polishing composition, the surface of the object to be polished (particularly a silicon wafer) is oxidized to form an oxide film, which increases the required polishing time. Specific examples of the oxidizing agent include hydrogen peroxide (H ２O ２ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, etc. The phrase "the polishing composition is substantially free of oxidizing agents" means that the polishing composition does not contain an oxidizing agent, at least intentionally. Therefore, a polishing composition that inevitably contains a trace amount of oxidizing agent due to raw materials, manufacturing method, etc. (for example, a polishing composition in which the molar concentration of the oxidizing agent in the polishing composition is 0.001 mol / L or less, preferably 0.0005 mol / L or less, more preferably 0.0001 mol / L or less, even more preferably 0.00005 mol / L or less, and particularly preferably 0.00001 mol / L or less) can be included in the concept of a polishing composition that is substantially free of oxidizing agents.

[0114] [Method for producing polishing composition] The method for producing the polishing composition of the present invention is not particularly limited. For example, the polishing composition can be produced by sequentially adding abrasive grains, a basic compound, a polyvinyl alcohol-based polymer, a polyhydric alcohol, and other components as needed, and stirring the mixture in a dispersion medium.

[0115] (Form of polishing composition, etc.) The polishing composition of the present invention may be a one-component type or a multi-component type consisting of two or more components. The polishing composition described above may be used for polishing as is, or may be prepared by adding water to dilute the concentrated solution of the polishing composition, or in the case of a multi-component polishing composition, by diluting it with an aqueous solution containing water and some of the constituents, and then used for polishing. For example, the concentrated solution of the polishing composition can be stored or transported, and then diluted at the time of use to prepare the polishing composition.

[0116] A concentrated polishing composition is advantageous from the viewpoint of convenience and cost reduction during production, distribution, storage, etc. The concentration ratio can be, for example, about 2 to 100 times in volume terms, and is usually about 5 to 50 times in volume terms. The concentration ratio of the polishing composition according to a preferred embodiment is 10 to 45 times, for example, 15 to 40 times.

[0117] [Object to be Polished] The polishing composition of the present invention is used to polish the surface of a silicon material.

[0118] The silicon material preferably contains at least one material selected from the group consisting of silicon single crystal, amorphous silicon, and polysilicon. From the viewpoint of obtaining the effects of the present invention more significantly, the silicon material is more preferably silicon single crystal or polysilicon, and particularly preferably silicon single crystal. The polishing composition according to some embodiments of the present invention is particularly preferably used for polishing a substrate (e.g., a silicon wafer) having a surface made of silicon single crystal.

[0119] The silicon wafer to be polished with the polishing composition of the present invention may be either p-type or n-type. The crystal orientation of the silicon wafer is not particularly limited and may be any of <100>, <110>, or <111>.

[0120] [Polishing Method] Another aspect of the present invention provides a polishing method comprising polishing a surface made of a silicon material using the polishing composition. The polishing composition according to some embodiments of the present invention is particularly suitable for use in a final polishing step because it is effective in improving the surface quality of the object to be polished. That is, the polishing method according to some embodiments of the present invention is suitable for use in a final polishing step. Therefore, the present invention also provides a method for manufacturing an object to be polished (e.g., a method for manufacturing a silicon wafer) comprising a final polishing step using the polishing composition. The final polishing step refers to the final polishing step in the manufacturing process of the object (i.e., a step after which no further polishing is performed). The polishing composition according to some embodiments of the present invention may also be used in a polishing step upstream of the final polishing step (a step between the rough polishing step and the final polishing step), for example, a polishing step performed immediately before the final polishing step.

[0121] As described above, the polishing composition according to some embodiments of the present invention is preferably used for polishing silicon wafers. The polishing composition according to some embodiments of the present invention is particularly suitable as a polishing composition used in the finish polishing step of silicon wafers. More specifically, the polishing composition according to some embodiments of the present invention is suitable for use in polishing silicon wafers that have been prepared to a surface state with a surface roughness of 0.01 nm or more and 100 nm or less by a step upstream of the finish polishing step.

[0122] As the polishing apparatus, a general polishing apparatus can be used, which is equipped with a holder for holding a substrate or the like having an object to be polished, a motor whose rotation speed can be changed, and a polishing platen to which a polishing pad (polishing cloth) can be attached.

[0123] The polishing pad can be made of any material, including general nonwoven fabric, polyurethane, suede, etc. The polishing pad is preferably provided with grooves for collecting the polishing composition.

[0124] The polishing conditions are appropriately set depending on the stage of the polishing process in which the polishing composition is used.

[0125] In the preliminary polishing step, either a double-sided polishing machine or a single-sided polishing machine may be used, but a single-sided polishing machine is preferably used. The rotation speed of the surface plate is usually about 10 rpm or more and 100 rpm or less, preferably about 20 rpm or more and 60 rpm or less. In the finish polishing step, a single-sided polishing machine is preferably used, and the rotation speed of the surface plate is usually about 10 rpm or more and 100 rpm or less, preferably about 20 rpm or more and 60 rpm or less, more preferably about 25 rpm or more and 55 rpm or less. At such a rotation speed, defects on the surface of the object to be polished can be significantly reduced. Note that 1 rpm = 0.017 s －１ is.

[0126] The object to be polished is usually pressed by a platen. The pressure at this time can be selected appropriately, but in the preliminary polishing step, it is usually preferably about 5 kPa to 30 kPa, more preferably about 10 kPa to 25 kPa. In addition, in the finish polishing step, it is usually preferably about 5 kPa to 30 kPa, more preferably about 10 kPa to 20 kPa. With such a pressure, defects on the surface of the object to be polished can be significantly reduced.

[0127] The supply rate of the polishing composition can also be appropriately selected depending on the size of the platen, but in terms of economy, in the case of the preliminary polishing step, it is usually preferably about 0.1 L / min to 5 L / min, and more preferably about 0.2 L / min to 2 L / min. In the case of the finish polishing step, it is usually preferably about 0.1 L / min to 5 L / min, and more preferably about 0.2 L / min to 2 L / min. Such a supply rate can efficiently polish the surface of the object to be polished and significantly reduce the haze level on the surface of the object to be polished.

[0128] There are no particular restrictions on the temperature at which the polishing composition is maintained in the polishing apparatus, but from the standpoint of stabilizing the polishing rate and reducing the haze level, it is generally preferably about 15°C or higher and 40°C or lower, and more preferably about 18°C ​​or higher and 25°C or lower.

[0129] The above polishing conditions (polishing apparatus settings) are merely examples, and may be outside the above ranges or may be changed as appropriate. Such conditions can be appropriately set by a person skilled in the art.

[0130] Furthermore, it is preferable to carry out cleaning and drying after polishing. The method and conditions for these operations are not particularly limited, and known methods may be used as appropriate. For example, SC-1 cleaning solution (ammonium hydroxide (NH ４ OH) and hydrogen peroxide (H ２ O ２ ) and water (H ２ O), SC-2 cleaning solution (hydrogen chloride (HCl) and H ２ O ２ and H ２For example, a cleaning solution such as an ozone water cleaning solution, a hydrofluoric acid cleaning solution, or the like can be used. The temperature of the cleaning solution can be set in the range of, for example, room temperature (typically about 15°C to 25°C) or higher and about 90°C or lower.

[0131] Although the embodiments of the present invention have been described in detail, it is clear that this is for illustrative and exemplary purposes only and not for limitation, and that the scope of the present invention should be interpreted by the appended claims.

[0132] The present invention encompasses the following aspects and configurations: 1. A polishing composition used for polishing a surface made of a silicon material, the polishing composition comprising abrasive grains, a basic compound, a polyvinyl alcohol-based polymer, and a polyhydric alcohol having a molecular weight of 600 or less; 2. The polishing composition according to 1. above, wherein the polyhydric alcohol is an unsaturated aliphatic polyhydric alcohol; 3. The polishing composition according to 2. above, wherein the unsaturated aliphatic polyhydric alcohol is a carbon-carbon triple bond-containing polyhydric alcohol; 4. The polishing composition according to any of 1. to 3. above, further comprising a water-soluble polymer different from the polyvinyl alcohol-based polymer; 5. The polishing composition according to any of 1. to 4. above, further comprising a dispersion medium; 6. A concentrate of the polishing composition according to any of 1. to 5. above; 7. A polishing method comprising polishing a surface made of a silicon material with the polishing composition according to any of 1. to 5. above.

[0133] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively. In the following examples, unless otherwise specified, the operations were carried out under the conditions of room temperature (25°C) and a relative humidity of 40% RH or more and 50% RH or less.

[0134] <Average Primary Particle Diameter of Abrasive Grains> The average primary particle diameter of the abrasive grains was calculated from the specific surface area of ​​colloidal silica measured by the BET method using a surface area measuring device manufactured by Micromeritics, product name "Flow Sorb II 2300", and the density of the abrasive grains.

[0135] <pH of Polishing Composition> The pH was measured using a pH meter (glass electrode hydrogen ion concentration indicator (model number F-2372) manufactured by Horiba, Ltd.). More specifically, three-point calibration was performed using standard buffer solutions (phthalate pH buffer solution, pH: 4.01 (25°C), neutral phosphate pH buffer solution, pH: 6.86 (25°C), carbonate pH buffer solution, pH: 10.01 (25°C)). Thereafter, the glass electrode was immersed in the polishing composition to be measured for 2 minutes or more. After the pH of the polishing composition stabilized, the pH of the polishing composition was measured.

[0136] <Measurement of Weight-Average Molecular Weight> The weight-average molecular weight was measured using a GPC method under the following conditions: <GPC Measurement Conditions> Measurement apparatus: HLC-8320GPC (manufactured by Tosoh Corporation) Sample concentration: 0.1 mass % Column: TSKgel (registered trademark) GMPWXL Detector: differential refractometer Eluent: 100 mM aqueous sodium nitrate solution Flow rate: 1 mL / min Measurement temperature: 40°C Molecular weight conversion: polyethylene glycol conversion Sample injection amount: 200 μL.

[0137] Example 1 Abrasive particles were prepared using colloidal silica (average primary particle diameter: 25 nm), ammonia as a basic compound, and a water-soluble polymer having a weight-average molecular weight (Mw) of 3.5×10 ５ and poly-N-acryloylmorpholine (PACMO) having a weight average molecular weight (Mw) of 1.0 × 10 ４ A concentrated polishing composition was prepared by mixing acetalized modified polyvinyl alcohol (Ac-PVA), polyoxyethylene decyl ether (ethylene oxide addition mole number: 5, C10PEO5) as a surfactant, glycerin as a polyhydric alcohol, and ion-exchanged water. The resulting concentrated polishing composition was diluted 40 times by volume with ion-exchanged water to obtain a polishing composition containing 0.13 mass% abrasive grains, 0.008 mass% ammonia, 0.004 mass% PACMO, 0.003 mass% Ac-PVA, 0.0006 mass% C10PEO5, and 0.0001 mass% glycerin, and having a pH of 10.19.

[0138] Example 2 A polishing composition was obtained in the same manner as in Example 1, except that 1,2-propanediol was used instead of glycerin.

[0139] Example 3 A polishing composition was obtained in the same manner as in Example 1, except that 2-butyne-1,4-diol was used instead of glycerin.

[0140] Example 4 A polishing composition was obtained in the same manner as in Example 1, except that polyglycerin (molecular weight: 300, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.) was used at a concentration of 0.05 mass % instead of glycerin. The molecular weight of the polyglycerin was the nominal value provided by the manufacturer.

[0141] Example 5 A polishing composition was obtained in the same manner as in Example 3, except that a random copolymer of vinyl alcohol and N-vinyl-2-pyrrolidone (PVA-PVP, weight average molecular weight: 6000) was used instead of Ac-PVA.

[0142] Example 6 A polishing composition was obtained in the same manner as in Example 3, except that polyvinyl alcohol (PVA, weight average molecular weight: 70,000) was used instead of Ac-PVA.

[0143] Comparative Example 1 A polishing composition was obtained in the same manner as in Example 1, except that glycerin was not used.

[0144] Comparative Example 2 A polishing composition was obtained in the same manner as in Example 1, except that ethanol was used instead of glycerin.

[0145] (Comparative Example 3) A polishing composition was obtained in the same manner as in Example 1, except that polyethylene glycol (molecular weight: 1000, manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of glycerin. The molecular weight of the polyethylene glycol is the nominal value of the manufacturer.

[0146] Comparative Example 4 A polishing composition was obtained in the same manner as in Example 5, except that 2-butyne-1,4-diol was not used.

[0147] Comparative Example 5 A polishing composition was obtained in the same manner as in Example 6, except that 2-butyne-1,4-diol was not used.

[0148] The compositions of the polishing compositions of Examples and Comparative Examples are shown in the following Table 1. In Table 1, "-" indicates that the component is not contained.

[0149]

[0150] [Polishing of Silicon Wafer] The surface of a silicon wafer was pre-polished under the following polishing condition 1. Next, the pre-polished surface of the silicon wafer was pre-polished using the polishing compositions of Examples and Comparative Examples under the following polishing condition 2. Furthermore, the pre-polished surface of the silicon wafer was final-polished (finish polished) using the polishing compositions of Examples and Comparative Examples under the following polishing condition 3.

[0151] The polished silicon wafer was then removed from the polishing apparatus. The removed silicon wafer was cleaned using a single-wafer wafer cleaning apparatus. First, the silicon wafer was cleaned with an ozone water cleaning solution for 60 seconds, and then cleaned with an SC-1 cleaning solution and a brush for 110 seconds. Next, the silicon wafer was cleaned with an ozone water cleaning solution for 20 seconds, and then cleaned with a hydrofluoric acid cleaning solution for 15 seconds. This ozone water cleaning and hydrofluoric acid cleaning constituted one set, and a total of three sets of cleaning were performed on the silicon wafer. After cleaning, the silicon wafer was further cleaned with an ozone water cleaning solution for 20 seconds. The silicon wafer was then dried.

[0152] [Polished Object] Wafer: A p-type COP (Crystal Organate 65d Particle)-free silicon wafer with a crystal orientation of <100> and a size of 300 mm was prepared.

[0153] [Preliminary polishing: Polishing condition 1] Polishing machine: PNX-332B (manufactured by Okamoto Machine Tool Works, Ltd.) Polishing pad: SUBA400 (manufactured by Nitta DuPont Co., Ltd.) Polishing load: 20 kPa Platen rotation speed: 20 rpm Carrier rotation speed: 20 rpm Polishing time: 2 min Platen cooling water temperature: 20°C Polishing composition temperature: 20°C Polishing composition supply rate: 1 L / min Polishing composition for preliminary polishing: a polishing composition containing 0.6 mass% of abrasive grains (colloidal silica having an average primary particle size of 35 nm) and 0.08 mass% of tetramethylammonium hydroxide (TMAH) in deionized water.

[0154] [Pre-polishing: Polishing condition 2] Polishing machine: PNX-332B (manufactured by Okamoto Machine Tool Works, Ltd.) Polishing pad: POLYPAS275NX (manufactured by Fujibo Ehime Co., Ltd.) Polishing load: 16 kPa Platen rotation speed: 52 rpm Carrier rotation speed: 50 rpm Polishing time: 2 min Platen cooling water temperature: 20°C Polishing composition temperature: 20°C Polishing composition supply rate: 1.5 L / min Polishing composition for pre-polishing: Polishing compositions of the Examples and Comparative Examples listed in Table 1.

[0155] [Finish polishing: Polishing condition 3] Polishing machine: PNX-332B (manufactured by Okamoto Machine Tool Works, Ltd.) Polishing pad: POLYPAS27NX (manufactured by Fujibo Ehime Co., Ltd.) Polishing load: 20 kPa Platen rotation speed: 52 rpm Carrier rotation speed: 50 rpm Polishing time: 2 min Platen cooling water temperature: 20°C Polishing composition temperature: 20°C Polishing composition supply rate: 1.5 L / min Polishing composition for finish polishing: Polishing compositions of Examples and Comparative Examples listed in Table 1.

[0156] [Evaluation] The number of defects (LLS, Localized Light Scatterers) on the wafer surface was measured using the dried silicon wafer. For the measurement, a wafer inspection device (manufactured by KLA Tencor Corporation, product name "SURFSCAN (registered trademark) SP5") was used, and the measurement mode was set to Oblique mode. The evaluation results are shown in Table 2 below. Table 2 below shows the relative values ​​(LLS ratios) of the number of defects in Examples 1 to 4 and Comparative Examples 2 and 3 when the number of defects (LLS) in Comparative Example 1 is set to 100, the relative value (LLS ratio) of the number of defects in Example 5 when the number of defects (LLS) in Comparative Example 4 is set to 100, and the relative value (LLS ratio) of the number of defects in Example 6 when the number of defects (LLS) in Comparative Example 5 is set to 100.

[0157]

[0158] As is clear from Table 2 above, it was found that when the polishing compositions of Examples 1 to 4 were used, the surface quality of the object to be polished after polishing could be improved compared to the polishing compositions of Comparative Examples 1 to 3. It was found that when the polishing composition of Example 5 was used, the surface quality of the object to be polished after polishing could be improved compared to the polishing composition of Comparative Example 4. It was found that when the polishing composition of Example 6 was used, the surface quality of the object to be polished after polishing could be improved compared to the polishing composition of Comparative Example 5.

[0159] This application is based on Japanese Patent Application No. 2023-164711, filed on September 27, 2023, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. A polishing composition used for polishing a surface made of a silicon material, comprising: an abrasive grain; a basic compound; a polyvinyl alcohol-based polymer; and a polyhydric alcohol having a molecular weight of 600 or less.

2. The polishing composition according to claim 1, wherein the polyhydric alcohol is an unsaturated aliphatic polyhydric alcohol.

3. The polishing composition according to claim 2, wherein the unsaturated aliphatic polyhydric alcohol is a carbon-carbon triple bond-containing polyhydric alcohol.

4. The polishing composition according to claim 1 or 2, further comprising a water-soluble polymer different from the polyvinyl alcohol-based polymer.

5. The polishing composition according to claim 1 or 2, further comprising a dispersion medium.

6. A concentrated solution of the polishing composition according to claim 1 or 2.

7. A polishing method comprising polishing a surface made of a silicon material with the polishing composition according to claim 1 or 2.

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