Polishing composition

Abstract

Provided is a polishing composition that offers suitable wettability of a surface after polishing and can effectively suppress defects such as haze lines. The polishing composition contains abrasive grains, a basic compound, an acetalized polyvinyl alcohol, and water. The acetalized polyvinyl alcohol includes a unit represented by formula (I) and a vinyl alcohol unit. The acetalization degree of the acetalized polyvinyl alcohol is more than 8% and less than 19%. (R1 is a hydrocarbon group.)

Description

polishing composition

[0001] The present invention relates to a polishing composition. This application claims priority to Japanese Patent Application No. 2024-99132, filed on June 19, 2024, the entire contents of which are incorporated herein by reference.

[0002] Precision polishing using a polishing composition is performed on the surfaces of materials such as metals, semi-metals, non-metals, and their oxides. For example, the surface of a silicon wafer used as a component of a semiconductor device is generally finished to a high-quality mirror surface through a lapping step (rough polishing step) and a polishing step (precise polishing step). The polishing step typically includes a pre-polishing step (preliminary polishing step) and a finish polishing step (final polishing step). Patent Document 1 is an example of a technical document related to a polishing composition mainly used for polishing semiconductor substrates such as silicon wafers.

[0003] Japanese Patent No. 6232243

[0004] Polishing compositions used in polishing semiconductor substrates such as silicon wafers and other substrates, for example, polishing compositions used in finish polishing processes (particularly finish polishing processes for semiconductor substrates such as silicon wafers and other substrates), are required to achieve high-quality surfaces after polishing. For example, by adding a water-soluble polymer to the polishing composition, the substrate is properly protected, which can improve the surface quality after polishing, such as by reducing the haze value. In addition, to obtain a high-quality surface, it is preferable that the surface after polishing has sufficient wettability. By keeping the polished surface wet with water (with a water film attached), it is possible to prevent foreign matter from directly adhering to the polished surface, making it easier to obtain a high-quality surface after cleaning. For example, Patent Document 1 discloses a wetting agent for semiconductors containing a water-soluble polymer obtained by the acetalization reaction of polyvinyl alcohol and an aldehyde compound.

[0005] On the other hand, when polishing with a polishing composition containing abrasive grains and a water-soluble polymer, if the water-soluble polymer does not sufficiently protect the substrate, defects such as minute scratches (haze lines) may be detected in surface inspection after polishing. The degree of the haze lines is evaluated, for example, by the total length of the haze lines present within a predetermined observation area, and it is desirable to shorten the total length in order to improve the surface quality after polishing. However, Patent Document 1 examines the improvement of wettability and etching resistance using a semiconductor wetting agent solution that does not contain abrasive grains, and does not evaluate the surface quality after polishing with a polishing composition containing abrasive grains.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polishing composition that has good wettability to the surface after polishing and can effectively suppress defects such as haze lines.

[0007] The present invention provides a polishing composition comprising abrasive grains, a basic compound, an acetalized polyvinyl alcohol, and water. The acetalized polyvinyl alcohol comprises a unit represented by the following formula (I) and a unit represented by the following formula (II). The acetalization degree of the acetalized polyvinyl alcohol is greater than 8% and less than 19%. A polishing composition comprising the acetalized polyvinyl alcohol having the above-described specific structure can effectively suppress defects such as haze lines while maintaining good wettability of the polished surface.

[0008] (R １ is a hydrocarbon group.

[0009] In some preferred embodiments, the polishing composition further contains a surfactant. A polishing composition containing a surfactant in addition to the acetalized polyvinyl alcohol tends to provide a higher surface quality.

[0010] The polishing composition disclosed herein may further contain a water-soluble polymer P2 selected from polymers other than the acetalized polyvinyl alcohol. A polishing composition containing the acetalized polyvinyl alcohol in combination with the water-soluble polymer P2 can achieve higher surface quality. The water-soluble polymer P2 may be, for example, one or more selected from the group consisting of nitrogen-containing polymers, non-acetalized polyvinyl alcohol-based polymers, polymers containing oxyalkylene units, starch derivatives, and cellulose derivatives.

[0011] In some embodiments, the polishing composition contains silica particles as the abrasive grains. A polishing composition containing silica particles as the abrasive grains tends to provide a polished surface with excellent surface quality.

[0012] In some embodiments, the polishing composition can be a concentrate. The polishing composition disclosed herein can be manufactured, distributed, and stored as a concentrate.

[0013] This specification provides a polishing method comprising the step of polishing a surface of a silicon material with the polishing composition, and the polished surface of the silicon material can have excellent wettability and reduced surface defects (e.g., haze lines).

[0014] Preferred embodiments of the present invention will be described below. It should be noted that matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field.

[0015] <Abrasive Grains> The polishing composition disclosed herein contains abrasive grains. The abrasive grains function to 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 purpose and usage of the polishing composition. Examples of abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate; and the like. 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), polyacrylonitrile particles, and the like. The abrasive grains may be used alone or in combination of two or more kinds.

[0016] The abrasive grains are preferably inorganic particles, and among these, particles made of metal or semi-metal oxides are preferred, with silica particles being particularly preferred. For example, in a polishing composition that can be used for polishing (e.g., finish polishing) of an object to be polished having a silicon surface, such as a silicon wafer, it is particularly meaningful to use silica particles as the abrasive grains. The technology disclosed herein can be preferably implemented, for example, in an embodiment in which the abrasive grains are essentially made of silica particles. Here, "substantially" means that 95% by weight or more (preferably 98% by weight or more, more preferably 99% by weight or more, and may be 100% by weight) of the particles constituting the abrasive grains are silica particles.

[0017] Specific examples of silica particles include colloidal silica, fumed silica, precipitated silica, etc. Silica particles can be used alone or in combination of two or more types. Colloidal silica is particularly preferred because it is easy to obtain a polished surface with excellent surface quality after polishing. As colloidal silica, for example, colloidal silica produced by an ion exchange method using water glass (sodium silicate) as a raw material, or alkoxide-method colloidal silica (colloidal silica produced by the hydrolysis and condensation reaction of alkoxysilane) can be preferably used. Colloidal silica can be used alone or in combination of two or more types.

[0018] The true specific gravity of the silica constituting the silica particles 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 the silica particles can be measured by a liquid substitution method using ethanol as a substitution liquid.

[0019] The average primary particle diameter of the abrasive grains (typically silica particles, preferably colloidal silica) is not particularly limited, but is preferably 5 nm or more, more preferably 10 nm or more, from the viewpoint of polishing removal rate, etc. From the viewpoint of obtaining a higher polishing effect (e.g., effects such as haze reduction and defect removal), the average primary particle diameter is preferably 15 nm or more, more preferably 20 nm or more (e.g., more than 20 nm). Furthermore, from the viewpoint of scratch prevention, etc., the average primary particle diameter of the abrasive grains is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 45 nm or less, and may be 43 nm or less, or may be less than 40 nm, less than 38 nm, less than 35 nm, less than 32 nm, or less than 30 nm.

[0020] In this specification, the average primary particle size of the abrasive grains is calculated from the specific surface area (BET value) measured by the BET method as follows: average primary particle size (nm) = 6000 / (true density (g / cm ３ ) × BET value (m ２The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritics, trade name "Flow Sorb II 2300."

[0021] The average secondary particle diameter of the abrasive grains (typically silica particles) is not particularly limited and can be appropriately selected, for example, from a range of about 15 nm to 300 nm. From the viewpoint of improving the polishing removal rate, the average secondary particle diameter is preferably 30 nm or more, more preferably 35 nm or more. In some embodiments, the average secondary particle diameter may be, for example, 40 nm or more, 42 nm or more, or preferably 44 nm or more. Furthermore, the average secondary particle diameter is usually advantageously 250 nm or less, preferably 200 nm or less, and more preferably 150 nm or less. In some preferred embodiments, the average secondary particle diameter is 120 nm or less, more preferably 100 nm or less, even more preferably 70 nm or less, for example, 60 nm or less, or even 50 nm or less.

[0022] In this specification, the average secondary particle size refers to the particle size (volume average particle size) measured by dynamic light scattering. The average secondary particle size of the abrasive grains can be measured by dynamic light scattering using, for example, a product named "Nanotrac UPA-UT151" manufactured by Nikkiso Co., Ltd.

[0023] The shape (external shape) of the abrasive grains may be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, confetti-shaped, and rugby ball-shaped. For example, abrasive grains in which most of the particles are peanut-shaped or cocoon-shaped can be preferably used.

[0024] Although not particularly limited, the average value of the ratio of the major axis to the minor axis of the abrasive grains (average aspect ratio) is, in principle, 1.0 or more, preferably 1.05 or more, more preferably 1.1 or more, and may be 1.2 or more. By increasing the average aspect ratio, a higher polishing removal 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, even more preferably 1.5 or less, and may be 1.4 or less.

[0025] The shape (outline) and average aspect ratio of abrasive grains can be determined, for example, by electron microscope observation. 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 abrasive grains 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.

[0026] <Basic Compound> The polishing composition disclosed herein contains a basic compound. In this specification, the term "basic compound" refers to a compound that dissolves in water and increases the pH of the aqueous solution. Examples of basic compounds that can be used include nitrogen-containing organic or inorganic basic compounds, alkali metal hydroxides, alkaline earth metal hydroxides, quaternary phosphonium compounds, various carbonates and hydrogen carbonates, etc. Examples of nitrogen-containing basic compounds include quaternary ammonium compounds, ammonia, amines (preferably water-soluble amines), etc. Such basic compounds can be used alone or in combination of two or more.

[0027] Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide. Specific examples of carbonates or bicarbonates include ammonium bicarbonate, ammonium carbonate, potassium bicarbonate, potassium carbonate, sodium bicarbonate, and sodium carbonate. 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. Specific examples of quaternary phosphonium compounds include quaternary phosphonium hydroxides such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

[0028] As the quaternary ammonium compound, a quaternary ammonium salt (typically a strong base) such as a tetraalkylammonium salt or a hydroxyalkyltrialkylammonium salt can be preferably used. The anion component in such a quaternary ammonium salt is, for example, OH － , F － , Cl － ,Br － , I － , ClO ４ － , B.H. ４ － Among these, a preferred example is one in which the anion is OH － Specific examples of quaternary ammonium hydroxides include tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide; hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide (also known as choline); and the like.

[0029] Among these basic compounds, at least one basic compound selected from, for example, alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia can be preferably used. Among these, potassium hydroxide, tetraalkylammonium hydroxide (e.g., tetramethylammonium hydroxide), and ammonia are more preferred, and ammonia is particularly preferred.

[0030] <Acetalized Polyvinyl Alcohol> The polishing composition disclosed herein contains acetalized polyvinyl alcohol as a water-soluble polymer. The acetalized polyvinyl alcohol used contains a unit represented by the above formula (I) (hereinafter also referred to as "unit (I)") and a unit represented by the above formula (II) (hereinafter also referred to as "unit (II)"). In a polishing composition containing abrasive grains, a basic compound, the acetalized polyvinyl alcohol, and water, by using one having an acetalization degree in the range of more than 8% and less than 19%, it is possible to achieve a high-quality surface in which defects such as haze lines are suppressed while maintaining good surface wettability after polishing. In this specification, the acetalization degree of the acetalized polyvinyl alcohol is defined as the number N of units (II) contained in the polyvinyl alcohol before acetalization. ０ and the number N of units (II) contained in the acetalized polyvinyl alcohol. １ and the following formula: Degree of acetalization [%] = (N ０ -N １ ) / N ０ × 100. Therefore, the degree of acetalization of the acetalized polyvinyl alcohol means how many of the OH groups of the units (II) contained in the polyvinyl alcohol before acetalization have been acetalized in the acetalized polyvinyl alcohol.

[0031] When the degree of acetalization is 8% or less, the hydrophobicity of the acetalized polyvinyl alcohol decreases, and the adsorption of the acetalized polyvinyl alcohol to the surface of the object to be polished tends to decrease. This tends to reduce the protection of the object to be polished. On the other hand, when the proportion of unit (I) exceeds 19%, the hydrophobicity of the acetalized polyvinyl alcohol increases, and the adsorption of the acetalized polyvinyl alcohol to the surface of the object to be polished tends to increase. This improves the protection of the surface of the object to be polished, but the decrease in the proportion of unit (II) tends to deteriorate the wettability of the surface after polishing. It is believed that by setting the proportion of unit (I) in the acetalized polyvinyl alcohol to be greater than 8% and less than 19%, it is possible to achieve both the protection of the surface of the object to be polished and the wettability of the surface after polishing. Note that the above mechanism is the inventors' consideration based on experimental results, and the technology disclosed herein should not be interpreted as being limited to the above mechanism.

[0032] In this specification, the degree of acetalization of the acetalized polyvinyl alcohol can be determined by nuclear magnetic resonance (NMR) measurement. As a specific measurement method, the method described in the examples below can be adopted.

[0033] Acetalized polyvinyl alcohol can be obtained by reacting a portion of the hydroxy groups of a polyvinyl alcohol-based polymer with an aldehyde compound or a ketone compound to acetalize the hydroxy groups. The acetalized polyvinyl alcohol used in the technology disclosed herein is typically obtained by an acetalization reaction between a polyvinyl alcohol-based polymer and an aldehyde compound or a ketone compound. The aldehyde compound or ketone compound is, for example, a compound represented by the formula (I) above, １ In some preferred embodiments, the acetalized polyvinyl alcohol may be a water-soluble polymer obtained by an acetalization reaction between a polyvinyl alcohol-based polymer and an aldehyde compound having 1 to 7 carbon atoms.

[0034] In this specification, the term "polyvinyl alcohol polymer" refers to a polymer having a -CH ２It refers to a polymer containing a vinyl alcohol unit represented by -CH(OH)-, i.e., a unit represented by the above formula (II) (i.e., unit (II), hereinafter also referred to as a "VA unit"), as a structural unit. The degree of saponification of the polyvinyl alcohol-based polymer may be, for example, 60% or more, and from the viewpoint of water solubility, it may be 70% or more, 80% or more, 90% or more, 95% or more, 97% or more, or 98% or more. In principle, the degree of saponification of the polyvinyl alcohol-based polymer is 100% or less.

[0035] In the technology disclosed herein, the polyvinyl alcohol polymer (PVA) used to produce acetalized polyvinyl alcohol may be either unmodified PVA or modified PVA. The unmodified PVA is produced by hydrolysis (saponification) of polyvinyl acetate, and contains structural units (-CH ２ -CH(OCOCH ３ In some preferred embodiments, the polyvinyl alcohol-based polymer is a polyvinyl alcohol-based polymer that is substantially free of structural units other than the VA unit and the VA unit.

[0036] In the technology disclosed herein, the aldehyde compound used to obtain acetalized polyvinyl alcohol is a compound consisting of carbon atoms and hydrogen atoms, excluding the oxygen atom contained in the aldehyde group. Specific examples of the aldehyde compound include formaldehyde; alkyl aldehydes (including linear alkyl aldehydes and branched alkyl aldehydes) such as acetaldehyde, propionaldehyde, n-butyl aldehyde, isobutyraldehyde, t-butyl aldehyde, n-pentyl aldehyde, and hexyl aldehyde; alicyclic or aromatic aldehydes such as cyclohexanecarbaldehyde and benzaldehyde; and the like. The aldehyde compounds may be used alone or in combination of two or more.

[0037] In some embodiments, the aldehyde compound is preferably one or more selected from the group consisting of formaldehyde and alkyl aldehydes having 2 to 7 carbon atoms, because they have high solubility in water and are easily acetalized. The acetalization reaction between a polyvinyl alcohol-based polymer and the aldehyde compound produces a unit represented by the following formula (IA) (hereinafter also referred to as "unit (IA)"):

[0038] (R ２ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0039] In some embodiments of the technology disclosed herein, the acetalized polyvinyl alcohol preferably has a structure containing the above unit (IA) and the above unit (II) and has an acetalization degree of more than 8% and less than 19%. ２ is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. ２ may be one of these, or a combination of two or more of them.

[0040] The acetalized polyvinyl alcohol in the technology disclosed herein has unit (I) (preferably unit (IA)) and unit (II), and has a degree of acetalization greater than 8% and less than 19%. When the degree of acetalization is greater than 8%, haze lines are significantly reduced. In some embodiments, the degree of acetalization may be 11% or more, 12% or more, 13% or more, or 14% or more. When the degree of acetalization is less than 19%, a good balance between reduced haze lines and good wettability can be achieved. In some embodiments, the degree of acetalization may be 18% or less, 17% or less, or 16% or less.

[0041] The weight average molecular weight (Mw) of the acetalized polyvinyl alcohol used in the polishing composition disclosed herein is not particularly limited. The Mw of the acetalized polyvinyl alcohol is usually 100×10 ４The following is appropriate: 30 x 10 ４ Preferably, 20 x 10 ４ or less (e.g., 10 x 10 ４ or less), and ４ It may be 5×10 or less. ４ It is advantageous that the Mw of the acetalized polyvinyl alcohol is not too large in terms of improving the uniformity of surface protection and reducing defects such as haze lines. From this perspective, in some embodiments, the Mw of the acetalized polyvinyl alcohol is 3.5 × 10 or less. ４ Preferably, it is 3×10 or less. ４ More preferably, it is 2.5 × 10 or less. ４ It may be 2×10 or less, ４ Less than (e.g., 2 x 10 ４ less than 1.5 × 10 ４ It may be less than 1.2 × 10 ４ It may be less than 1 × 10 ４ The Mw of the acetalized polyvinyl alcohol may be, for example, 4×10 ３ That's it, 5 x 10 ３ or more or 6 x 10 ３ or more, and tends to exhibit a suitable adsorption to the surface to be polished. ３ It is preferable that the ratio is 8×10 or more. ３ More preferably, it is equal to or greater than this.

[0042] In this specification, the weight average molecular weight (Mw) of acetalized polyvinyl alcohol, other water-soluble polymers, and surfactants can be a value based on aqueous gel permeation chromatography (GPC) (aqueous, polyethylene oxide equivalent). A GPC measuring device manufactured by Tosoh Corporation with the model name "HLC-8320GPC" can be used. The measuring conditions are as follows. The same method is also used in the examples described below. [GPC measuring conditions] Sample concentration: 0.1 wt% Column: TSKgel GMPW ＸＬDetector: differential refractometer Eluent: 100 mM aqueous sodium nitrate solution / acetonitrile = 10-8 / 0-2 Flow rate: 1 mL / min Measurement temperature: 40°C Sample injection volume: 100 μL

[0043] Although not particularly limited, the content of acetalized polyvinyl alcohol in the polishing composition can be, for example, 0.05 parts by weight or more relative to 100 parts by weight of abrasive grains, and is usually suitably 0.1 parts by weight or more.From the viewpoint of better reducing defects such as haze lines, in some embodiments, the content of acetalized polyvinyl alcohol relative to 100 parts by weight of abrasive grains is preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, even more preferably 1.0 parts by weight or more, and may be 2.0 parts by weight or more or 2.5 parts by weight or more.In addition, from the viewpoint of easily obtaining a processing force suitable for the polishing process using the polishing composition disclosed herein, the content of acetalized polyvinyl alcohol relative to 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, 30 parts by weight or less, or 20 parts by weight or less. From the viewpoint of making it easier to obtain a higher processing force, in some embodiments, the content of acetalized polyvinyl alcohol per 100 parts by weight of abrasive grains is suitably 15 parts by weight or less, preferably 10 parts by weight or less, and may be 7.0 parts by weight or less, 5.0 parts by weight or less, 4.0 parts by weight or less, 3.5 parts by weight or less, or 3.0 parts by weight or less.

[0044] <Water-soluble polymer P2> The polishing composition disclosed herein may contain, as an optional component, a water-soluble polymer P2 selected from polymers other than the above-mentioned acetalized polyvinyl alcohol, in addition to the above-mentioned acetalized polyvinyl alcohol (hereinafter also referred to as "water-soluble polymer P1"). The water-soluble polymer P2 can be useful for improving the protection and wettability of the surface to be polished. As the water-soluble polymer P2, any of nonionic, anionic, and cationic polymers can be used. For example, a polymer having at least one of a hydroxyl group, a carboxyl group, an acyloxy group, a sulfo group, a primary amide structure, a heterocyclic structure, a vinyl structure, a polyoxyalkylene structure, etc. in the molecule can be used as the water-soluble polymer P2. The water-soluble polymer P2 can be used alone or in combination of two or more types. From the viewpoints of reducing aggregates and improving cleanability, etc., in some embodiments, a nonionic polymer can be preferably used as the water-soluble polymer P2.

[0045] Examples of the water-soluble polymer P2 include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers other than the above-mentioned acetalized polyvinyl alcohols (for example, non-acetalized polyvinyl alcohol-based polymers), polymers containing nitrogen atoms, carboxylic acid-based polymers, etc. Among these, preferred examples include polymers containing nitrogen atoms, cellulose derivatives, and non-acetalized polyvinyl alcohol-based polymers.

[0046] Cellulose derivatives are polymers containing β-glucose units as the main repeating unit. Specific examples of cellulose derivatives include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, and carboxymethyl cellulose. Of these, HEC is preferred.

[0047] Starch derivatives are polymers containing α-glucose units as the main repeating unit. Specific examples of starch derivatives include pregelatinized starch, pullulan, carboxymethyl starch, and cyclodextrin. Of these, pullulan is preferred.

[0048] Examples of polymers containing oxyalkylene units include polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) and propylene oxide (PO) or butylene oxide (BO), and random copolymers of EO and PO or BO. Among these, block copolymers of EO and PO or random copolymers of EO and PO are preferred. The block copolymer of EO and PO may be a diblock copolymer or triblock copolymer containing a PEO block and a polypropylene oxide (PPO) block. Examples of the triblock copolymer include PEO-PPO-PEO type triblock copolymers and PPO-PEO-PPO type triblock copolymers. Typically, PEO-PPO-PEO type triblock copolymers are more preferred.

[0049] In this specification, unless otherwise specified, the term "copolymer" refers collectively to various copolymers such as random copolymers, alternating copolymers, block copolymers, and graft copolymers.

[0050] In a block copolymer or random copolymer of EO and PO, the molar ratio of EO to PO (EO / PO) constituting the copolymer is preferably greater than 1, more preferably 2 or more, and even more preferably 3 or more (e.g., 5 or more), from the viewpoints of solubility in water, washability, etc.

[0051] Examples of polyvinyl alcohol-based polymers (hereinafter simply referred to as "polyvinyl alcohol-based polymers") that do not fall under the above-mentioned acetalized polyvinyl alcohol (water-soluble polymer P1) include non-acetalized polyvinyl alcohol-based polymers and acetalized polyvinyl alcohols that do not satisfy the requirements for the degree of acetalization for the water-soluble polymer P1. Non-acetalized polyvinyl alcohol-based polymers are typically polyvinyl alcohol-based polymers that contain vinyl alcohol units (VA units) as the main repeating units and do not contain acetalized structural units. The polyvinyl alcohol-based polymer serving as the water-soluble polymer P2 may contain only 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 polyvinyl alcohol-based polymer may be a random copolymer containing VA units and non-VA units, or may be a block copolymer or a graft 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.

[0052] The polyvinyl alcohol-based polymer may be unmodified polyvinyl alcohol (unmodified PVA) or modified polyvinyl alcohol (modified PVA). The degree of saponification of the polyvinyl alcohol-based polymer may be, for example, 60% or more, or, from the viewpoint of water solubility, 70% or more, 80% or more, 90% or more, 95% or more, 97% or more, or 98% or more.

[0053] The polyvinyl alcohol-based polymer may be a modified PVA containing VA units and non-VA units having at least one structure selected from the group consisting of oxyalkylene groups, carboxy groups, (di)carboxylic acid groups, (di)carboxylic acid ester groups, phenyl groups, naphthyl groups, sulfo groups, amino groups, hydroxyl groups, amide groups, imide groups, nitrile groups, ether groups, ester groups, and salts thereof. The non-VA units that may be contained in the modified PVA may be, for example, 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, but are not limited thereto. A preferred example of the N-vinyl monomer is N-vinylpyrrolidone. 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 from 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 from 3 to 7 carbon atoms may be, for example, a vinyl ester of a monocarboxylic acid having from 3 to 7 carbon atoms, such as vinyl propanoate, vinyl butanoate, vinyl pentanoate, or vinyl hexanoate. Examples of the (di)acetone compound include diacetone (meth)acrylamide and acetylacetone. As the polyvinyl alcohol-based polymer, a cationically modified polyvinyl alcohol into which a cationic group such as a quaternary ammonium structure has been introduced may be used. Examples of the cationically modified polyvinyl alcohol include those into which a cationic group derived from a monomer having a cationic group, such as diallyldialkylammonium salt or N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salt, has been introduced. As the polyvinyl alcohol-based polymer, a polyvinyl alcohol having a non-VA unit represented by the chemical formula: -CH ２ -CH(CR ３ (OR ６ )-CR ４ (OR ７ )-R５ )-, where R ３ ~R ５ each independently represents a hydrogen atom or an organic group, R ６ and R ７ are each independently a hydrogen atom or R ８ -CO- (wherein, R ８ represents an alkyl group. For example, R ３ ~R ５ 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 may be a linear or branched alkyl group having 1 to 8 carbon atoms. In some embodiments, a modified PVA having a 1,2-diol structure in a side chain is used as the polyvinyl alcohol-based polymer. For example, the modified PVA may be ３ ~R ７ A modified PVA (butenediol-vinyl alcohol copolymer (BVOH)) containing a non-VA unit in which is a hydrogen atom can be preferably used.

[0054] In this specification, the term "(meth)acryloyl" refers to both acryloyl and methacryloyl types. Similarly, the term "(meth)acrylic" refers to both acrylic and methacrylic types.

[0055] 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.

[0056] The content of VA units in the polyvinyl alcohol-based polymer (content by weight) may be, for example, 5% by weight or more, 10% by weight or more, 20% by weight or more, or 30% by weight or more. While not particularly limited, in some embodiments, the content of VA units may be 50% by weight or more (e.g., more than 50% by weight), 70% by weight or more, or 80% by weight or more (e.g., 90% by weight or more, 95% by weight or more, or 98% by weight or more). Substantially 100% by weight of the repeating units constituting the polyvinyl alcohol-based polymer may be VA units. Here, "substantially 100% by weight" 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 weight (e.g., less than 1% by weight). In some other embodiments, the content of VA units in the polyvinyl alcohol-based polymer may be, for example, 95% by weight or less, 90% by weight or less, 80% by weight or less, or 70% by weight or less.

[0057] 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 weight and a polymer chain B with a VA unit content of less than 50% by weight (i.e., a non-VA unit content of more than 50% by weight).

[0058] 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 weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In some embodiments, the content of VA units in the polymer chain A may be 95% by weight or more, or 98% by weight or more. Substantially 100% by weight of the repeating units constituting the polymer chain A may be VA units.

[0059] 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 weight or more, 70% by weight or more, 80% by weight or more, or 90% by weight or more. In some embodiments, the content of non-VA units in polymer chain B may be 95% by weight or more, or 98% by weight or more. Substantially 100% by weight of the repeating units constituting polymer chain B may be non-VA units.

[0060] 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.

[0061] 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, the term "main repeating unit" refers to a repeating unit contained in an amount of more than 50% by weight, unless otherwise specified.

[0062] 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 weight, and may be 70% by weight or more, 85% by weight or more, or 95% by weight or more. Substantially all of the polymer chain B may be repeating units derived from N-vinyl monomers.

[0063] Examples of N-vinyl monomers include monomers having a nitrogen-containing heterocycle (e.g., a lactam ring) and N-vinyl linear amides. Specific examples of N-vinyl lactam monomers include N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione. Specific examples of N-vinyl linear 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 weight (e.g., 70% by weight or more, 85% by weight or more, or 95% by weight or more) of its repeating units are N-vinylpyrrolidone units. Substantially all of the repeating units constituting polymer chain B may be N-vinylpyrrolidone units.

[0064] Another example of polymer chain B is a polymer chain having a repeating unit derived from an N-(meth)acryloyl-type monomer as the main repeating unit, i.e., an N-(meth)acryloyl-based polymer chain. 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 weight, and may be 70% by weight or more, 85% by weight or more, or 95% by weight or more. Substantially all of polymer chain B may be repeating units derived from N-(meth)acryloyl-type monomers.

[0065] 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.

[0066] Other examples of polymer chain B include polymer chains containing oxyalkylene units as main repeating units, i.e., oxyalkylene-based polymer chains. The content of oxyalkylene units in the oxyalkylene-based polymer chain is typically more than 50% by weight, and may be 70% by weight or more, 85% by weight or more, or 95% by weight or more. Substantially all of the repeating units contained in polymer chain B may be oxyalkylene units.

[0067] 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 one type or 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.

[0068] Further examples of the polymer chain B include a polymer chain containing a repeating unit derived from an alkyl vinyl ether (e.g., a vinyl ether having an alkyl group having from 1 to 10 carbon atoms), a polymer chain containing a repeating unit derived from a monocarboxylic acid vinyl ester (e.g., a vinyl ester of a monocarboxylic acid having from 3 or more carbon atoms), and a polymer chain into which a cationic group (e.g., a cationic group having a quaternary ammonium structure) has been introduced.

[0069] Non-limiting examples of polymers containing nitrogen atoms include polymers containing N-vinyl type monomer units; imine derivatives; polymers containing N-(meth)acryloyl type monomer units; and the like.

[0070] Examples of polymers containing N-vinyl monomer units include polymers containing repeating units derived from monomers having a nitrogen-containing heterocycle (e.g., 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 weight), homopolymers and copolymers of N-vinyl linear amides (e.g., copolymers in which the copolymerization ratio of N-vinyl linear amides exceeds 50% by weight), and the like.

[0071] Specific examples of N-vinyl lactam monomers (i.e., compounds having a lactam structure and an N-vinyl group in one molecule) include N-vinylpyrrolidone (VP), N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam (VC), N-vinyl-1,3-oxazin-2-one, and N-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.), and block 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.

[0072] Examples of polymers containing N-(meth)acryloyl type monomer units 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% by weight). 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.

[0073] 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. Other examples include N-hydroxyethylacrylamide (HEAA). Examples of polymers containing chain amides 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 weight).

[0074] 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 monomer units include acryloylmorpholine-based polymers (PACMO). Typical examples of acryloylmorpholine-based polymers include homopolymers of N-acryloylmorpholine (ACMO) and copolymers of ACMO (e.g., copolymers in which the copolymerization ratio of ACMO exceeds 50% by weight). In acryloylmorpholine-based polymers, the proportion of the number of moles of ACMO units in the number of moles of all repeating units is typically 50% or more, and suitably 80% or more (e.g., 90% or more, typically 95% or more). It may also be an acryloylmorpholine-based polymer substantially composed of ACMO units.

[0075] Examples of carboxylic acid polymers include polymers containing maleic acid units and polymers containing (meth)acrylic acid units. Examples of polymers containing maleic acid units include styrene-maleic acid copolymers or salts thereof, styrene-maleic anhydride copolymers, styrene sulfonic acid-maleic acid copolymers or salts thereof, copolymers of styrene sulfonate and maleic acid, and maleic acid-vinyl acetate copolymers. Examples of polymers containing (meth)acrylic acid units include polyacrylic acid or salts thereof, styrene-acrylic acid copolymers or salts thereof, styrene sulfonic acid-acrylic acid copolymers or salts thereof, copolymers of styrene sulfonate and acrylic acid, acrylic acid-vinyl acetate copolymers, and acrylic acid / sulfonic acid monomer copolymers. In this specification, (meth)acrylic acid is meant to refer collectively to acrylic acid and methacrylic acid.

[0076] The weight average molecular weight (Mw) of the water-soluble polymer P2 is not particularly limited. ３ or more, and may be 1×10 ４ It may be 5×10 or more. ４ It may be 10×10 or more. ４ Or more, 20 x 10 ４ Or more, 25 x 10 ４ More than 30 x 10 ４ Or more, 40 x 10 ４ Or more, 45 x 10 ４ The Mw of the water-soluble polymer P2 is usually 150×10 ４ The following is appropriate: 100 x 10 ４ Less than 80 x 10 ４ The following is preferred: 60 x 10 ４ Less than (e.g., 50 x 10 ４ (See below) may also be used.

[0077] The ratio (Mw1 / Mw2) of the Mw (Mw1) of the water-soluble polymer P1 to the Mw (Mw2) of the water-soluble polymer P2 is not particularly limited. Mw1 / Mw2 may be, for example, 10 or less, 2 or less, 1.5 or less, or 1 or less. In some preferred embodiments, the Mw of the water-soluble polymer P2 is selected so that the Mw of the water-soluble polymer P1 is smaller than the Mw of the water-soluble polymer P2. By using a water-soluble polymer P1 having a relatively small Mw in combination with a water-soluble polymer P2 having a relatively large Mw, the uniformity of protection of the surface of the object to be polished can be improved and defects such as haze lines on the polished surface can be more effectively reduced. In some preferred embodiments, the ratio of the Mw (Mw1) of the water-soluble polymer P1 to the Mw (Mw2) of the water-soluble polymer P2 (Mw2) (Mw1 / Mw2) is less than 1, and may be 0.7 or less, 0.5 or less (e.g., less than 0.5), 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.04 or less, 0.035 or less, 0.03 or less, 0.025 or less, or 0.02 or less. In some embodiments, the ratio (Mw1 / Mw2) may be, for example, 0.001 or more, 0.005 or more, 0.01 or more, or 0.015 or more.

[0078] In embodiments in which the polishing composition contains a water-soluble polymer P2, the content of the water-soluble polymer P2 in the polishing composition is not particularly limited. The content of the water-soluble polymer P2 in the polishing composition can be, for example, 0.001 parts by weight or more, or 0.01 parts by weight or more, or 0.1 parts by weight or more, or even 0.3 parts by weight or more, relative to 100 parts by weight of the abrasive grains. From the viewpoint of more easily achieving the effects of using the water-soluble polymer P2, in some embodiments, the content of the water-soluble polymer P2 relative to 100 parts by weight of the abrasive grains is preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more, or even 2.0 parts by weight or more, or even 3.0 parts by weight or more, or even 3.5 parts by weight or more. Furthermore, from the viewpoint of making it easier to obtain a processing force suitable for the polishing process in which the polishing composition disclosed herein is used, the content of water-soluble polymer P2 per 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 7.0 parts by weight or less, or 5.0 parts by weight or less.

[0079] Although not particularly limited, in some embodiments, the total content of the water-soluble polymers contained in the polishing composition (the total amount of the water-soluble polymer P1 and other water-soluble polymers used as needed) can be, for example, 0.02 parts by weight or more per 100 parts by weight of abrasive grains. From the viewpoint of improving surface quality, etc., it is appropriate to set it to 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more, even more preferably 2.0 parts by weight or more (e.g., 2.5 parts by weight or more). It may be 3.0 parts by weight or more, 4.0 parts by weight or more, 5.0 parts by weight or more, or even 6.0 parts by weight or more. Furthermore, the total content of the water-soluble polymers per 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, or may be 30 parts by weight or less. From the viewpoint of the dispersion stability of the polishing composition, etc., in some embodiments, the total content of the water-soluble polymers per 100 parts by weight of abrasive grains is appropriate to be 15 parts by weight or less, preferably 12 parts by weight or less, or may be 10 parts by weight or less (e.g., less than 10 parts by weight).

[0080] Content W of water-soluble polymer P2 ２ The content W of the water-soluble polymer P1 relative to １ The ratio (W １ / W ２ ) is, for example, 0.01 or more, preferably 0.05 or more, and more preferably 0.1 or more, on a weight basis. In some preferred embodiments, the ratio (W １ / W ２ ) may be 0.3 or more, 0.5 or more, 0.6 or more, or 0.7 or more. １ / W ２ ) is, for example, 30 or less, suitably 20 or less, may be 10 or less, or may be 7 or less. In some preferred embodiments, the ratio (W １ / W ２ ) is suitably 5 or less, preferably 3 or less, more preferably 2 or less, and may be 1 or less (for example, less than 1), 0.9 or less, or 0.8 or less. １ / W ２ By appropriately setting the above ranges, the effects of the technology disclosed herein can be preferably exhibited.

[0081] <Surfactant> In some embodiments, the polishing composition preferably contains a surfactant. The use of a surfactant can further improve the quality of the polished surface. Any of anionic, cationic, nonionic, and amphoteric surfactants can be used as the surfactant. Generally, anionic or nonionic surfactants are preferred. Nonionic surfactants are more preferred from the viewpoints of low foaming and ease of pH adjustment. The use of nonionic surfactants tends to further improve the reduction of defects (e.g., haze lines). Examples of nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene derivatives (e.g., 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 surfactants can be used alone or in combination of two or more.

[0082] Specific examples of nonionic surfactants 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, polyoxyethylene octyl ether, polyoxyethylene ... Examples of the hydroxypropyl ether include 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 (e.g., polyoxyethylene decyl ether).As the polyoxyethylene alkyl ether, those having an EO addition mole number of about 1 to 10 (e.g., about 3 to 8) can be preferably used.

[0083] The molecular weight of the surfactant is, for example, less than 5000, preferably less than 3000. By using a surfactant with a molecular weight of less than 3000, a polishing composition with excellent defect reduction properties is easily obtained. In some preferred embodiments, the molecular weight of the surfactant is, for example, less than 2000, more preferably 1900 or less (e.g., less than 1800), even more preferably 1500 or less, and may be 1000 or less (e.g., 500 or less). Furthermore, from the viewpoint of surface activity, etc., the molecular weight of the surfactant is usually suitably 200 or more, preferably 250 or more (e.g., 300 or more).

[0084] The preferred range of the molecular weight of the surfactant may vary depending on the type of surfactant. For example, when a polyoxyethylene alkyl ether is used as the surfactant, the molecular weight is preferably less than 2000, more preferably 1900 or less (e.g., less than 1800), even more preferably 1500 or less, and may be 1000 or less (e.g., 500 or less). Furthermore, when a block copolymer of EO and PO is used as the surfactant, the weight-average molecular weight may be, for example, 500 or more, 1000 or more, even 1500 or more, 2000 or more, or even 2500 or more. The upper limit of the weight-average molecular weight is, for example, less than 5000, preferably 4500 or less, and may be, for example, less than 4000 or less, or may be, for example, less than 3500.

[0085] The molecular weight of the surfactant may be the molecular weight calculated from the chemical formula, or the weight average molecular weight determined by the GPC method. For example, in the case of polyoxyethylene alkyl ether, it is preferable to use the molecular weight calculated from the chemical formula, and in the case of a block copolymer of EO and PO, it is preferable to use the weight average molecular weight determined by the GPC method.

[0086] Although not particularly limited, in an embodiment in which the polishing composition contains a surfactant, the content of the surfactant is usually 20 parts by weight or less relative to 100 parts by weight of abrasive grains (typically silica particles) from the viewpoint of cleaning properties, etc., preferably 10 parts by weight or less, more preferably 5 parts by weight or less, even more preferably 3 parts by weight or less, particularly preferably 1 part by weight or less (for example, less than 1 part by weight), and may be 0.8 parts by weight or less, may be 0.6 parts by weight or less, may be 0.4 parts by weight or less, or may be 0.2 parts by weight or less. From the viewpoint of better exerting the effect of using the surfactant, the content of the surfactant relative to 100 parts by weight of abrasive grains is appropriately 0.001 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, may be 0.1 parts by weight or more, or may be 0.3 parts by weight or more.

[0087] Although not particularly limited, in an embodiment in which the polishing composition contains a surfactant, the content W of the acetalized polyvinyl alcohol (water-soluble polymer P1) １ Surfactant content W Ｓ The ratio (W Ｓ / W １ ) can be, for example, 0.001 or more on a weight basis, and from the viewpoint of reducing defects, etc., it is appropriate to set it to 0.005 or more, preferably 0.01 or more, more preferably 0.02 or more, and may be 0.03 or more. In some embodiments, the ratio (W Ｓ / W １ ) may be, for example, 10 or less on a weight basis, and from the viewpoint of reducing defects, etc., it is appropriate to be 1 or less (for example, less than 1), preferably 0.5 or less, more preferably 0.3 or less. In some embodiments, the ratio (W Ｓ / W１ ) may be 0.2 or less, 0.1 or less, or 0.07 or less.

[0088] Although not particularly limited, in an embodiment in which the polishing composition contains the water-soluble polymer P2 and a surfactant, the content W of the water-soluble polymer P2 ２ Surfactant content W Ｓ The ratio (W Ｓ / W ２ ) can be, for example, 0.001 or more, suitably 0.003 or more, preferably 0.005 or more, more preferably 0.007 or more, and may be 0.009 or more, or may be 0.01 or more, on a weight basis. In some embodiments, the ratio (W Ｓ / W ２ ) may be, for example, 5 or less on a weight basis, and from the viewpoint of reducing defects, etc., it is suitably 1 or less (for example, less than 1), preferably 0.5 or less, more preferably 0.3 or less, and may be, for example, 0.2 or less, or may be 0.17 or less.

[0089] Although not particularly limited, in an embodiment in which the polishing composition contains a surfactant, the total content W of the water-soluble polymer Ｐ Surfactant content W Ｓ The ratio (W Ｓ / W Ｐ ) can be, for example, 0.001 or more on a weight basis, and from the viewpoint of reducing defects, etc., it is appropriate to set it to 0.005 or more, preferably 0.01 or more, more preferably 0.03 or more, and may be 0.05 or more, or may be 0.07 or more. In some embodiments, the above ratio (W Ｓ / W Ｐ ) may be, for example, 10 or less on a weight basis, and from the viewpoint of reducing defects, etc., it is appropriate to be 1 or less (for example, less than 1), preferably 0.5 or less, more preferably 0.3 or less, for example, 0.15 or less, or even 0.1 or less. In an embodiment that does not contain a water-soluble polymer other than the acetalized polyvinyl alcohol (water-soluble polymer P1), W １ and W Ｐ is consistent with

[0090] <Water> The water contained in the polishing composition disclosed herein can preferably be ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. In order to minimize the inhibition of the functions of other components contained in the polishing composition, the water used preferably has a total transition metal ion content of, for example, 100 ppb or less. For example, the purity of the water can be increased by removing impurity ions using an ion exchange resin, removing foreign matter using a filter, distillation, or other procedures.

[0091] <Other Components> The polishing composition disclosed herein may further contain, as necessary, known additives that can be used in polishing compositions (e.g., polishing compositions used in the finish polishing step of silicon wafers), such as organic acids, organic acid salts, inorganic acids, inorganic acid salts, chelating agents, preservatives, and antifungal agents, within the range that does not significantly impair the effects of the present invention.

[0092] The organic acids and their salts, and the inorganic acids and their salts can be used alone or in combination of two or more. Examples of organic acids include fatty acids such as formic acid, acetic acid, and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, itaconic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, glycolic acid, malonic acid, gluconic acid, alanine, glycine, lactic acid, organic sulfonic acids such as hydroxyethylidene diphosphate (HEDP) and methanesulfonic acid, and organic phosphonic acids such as nitrilotris(methylene phosphate) (NTMP) and phosphonobutanetricarboxylic acid (PBTC). Examples of organic acid salts include alkali metal salts (sodium salt, potassium salt, lithium salt, etc.) and ammonium salts of organic acids. Examples of inorganic acids include hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, and carbonic acid. Examples of inorganic acid salts include alkali metal salts (sodium salts, potassium salts, lithium salts, etc.) and ammonium salts of inorganic acids.

[0093] The chelating agent may be used alone or in combination of two or more. Examples of the chelating agent include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Suitable examples of the chelating agent include ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and diethylenetriaminepentaacetic acid. Examples of the preservatives and antifungal agents include isothiazolinone compounds, parahydroxybenzoic acid esters, phenoxyethanol, etc.

[0094] The polishing composition disclosed herein preferably does not substantially contain an oxidizing agent. If an oxidizing agent is contained in the polishing composition, when the polishing composition is supplied to a substrate (e.g., a silicon wafer), the surface of the substrate may be oxidized to form an oxide film, which may result in a decrease in the polishing removal rate. Specific examples of the oxidizing agent referred to here include hydrogen peroxide (H ２ O ２ ), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, etc. In addition, "the polishing composition is substantially free of an oxidizing agent" means that the oxidizing agent is not contained 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 an oxidizing agent as used herein.

[0095] <pH> The pH of the polishing composition disclosed herein is typically 8.0 or more, preferably 8.5 or more, more preferably 9.0 or more, even more preferably 9.3 or more, for example, 9.5 or more. When the pH of the polishing composition is high, the polishing efficiency tends to improve. On the other hand, from the viewpoint of preventing dissolution of abrasive grains (e.g., silica particles) and suppressing a decrease in mechanical polishing action, the pH of the polishing composition is suitably 12.0 or less, preferably 11.0 or less, more preferably 10.8 or less, and even more preferably 10.5 or less.

[0096] In the technology disclosed herein, the pH of the polishing composition is measured using a pH meter (for example, a glass electrode hydrogen ion concentration indicator (Model F-72) manufactured by Horiba, Ltd.). More specifically, a three-point calibration is 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)), and then the glass electrode is placed in the polishing composition to be measured for 2 minutes or more. After the pH of the polishing composition has stabilized, the pH of the polishing composition is measured.

[0097] <Polishing Liquid> The polishing composition disclosed herein is typically supplied to an object to be polished in the form of a polishing liquid containing the polishing composition, and used to polish the object to be polished. The polishing liquid may be prepared, for example, by diluting any of the polishing compositions disclosed herein (typically with water). Alternatively, the polishing composition may be used as a polishing liquid as is. Another example of a polishing liquid containing the polishing composition disclosed herein is a polishing liquid obtained by adjusting the pH of the composition.

[0098] The content of abrasive grains in the polishing liquid is not particularly limited, and is, for example, 0.01 wt % or more, preferably 0.05 wt % or more, more preferably 0.10 wt % or more, for example, 0.15 wt % or more. By increasing the content of abrasive grains, a higher polishing rate can be achieved. From the viewpoint of dispersion stability of particles in the polishing liquid, the content of abrasive grains in the polishing liquid is usually 10 wt % or less, preferably 7 wt % or less, more preferably 5 wt % or less, and even more preferably 2 wt % or less, for example, 1 wt % or less, and may be 0.7 wt % or less. In a preferred embodiment, the content of abrasive grains in the polishing liquid may be 0.5 wt % or less, or may be 0.2 wt % or less. This makes it easier to maintain surface quality.

[0099] The content of the basic compound in the polishing liquid is not particularly limited. From the viewpoint of improving the polishing removal rate, etc., it is usually appropriate that the content is 0.0005 wt % or more, preferably 0.001 wt % or more, more preferably 0.003 wt % or more, and even more preferably 0.005 wt % or more (e.g., more than 0.005 wt %). Furthermore, from the viewpoint of improving the surface quality, etc., it is appropriate that the content is less than 0.5 wt %, preferably less than 0.1 wt %, more preferably less than 0.05 wt %, and even more preferably less than 0.03 wt % (e.g., less than 0.025 wt %, or even less than 0.01 wt %).

[0100] The content of acetalized polyvinyl alcohol (water-soluble polymer P1) in the polishing liquid is not particularly limited, and may be, for example, 0.0001 wt% or more, or 0.0005 wt% or more. From the viewpoint of better reducing haze lines, in some embodiments, the content is preferably 0.001 wt% or more, more preferably 0.002 wt% or more, and even more preferably 0.003 wt% or more. Furthermore, the content of acetalized polyvinyl alcohol in the polishing composition can be, for example, 1.0 wt% or less. From the viewpoint of obtaining a processing force suitable for the polishing process in which the polishing composition disclosed herein is used, in some embodiments, the content is suitably 0.1 wt% or less, preferably 0.05 wt% or less, and may be 0.02 wt% or less, 0.01 wt% or less, or 0.008 wt% or less.

[0101] When the polishing composition contains the water-soluble polymer P2, the content of the water-soluble polymer P2 in the polishing liquid is not particularly limited, and may be, for example, 0.0001 wt% or more, or 0.0005 wt% or more. From the viewpoint of improving surface quality, the preferred content is 0.001 wt% or more, more preferably 0.0015 wt% or more, and even more preferably 0.002 wt% or more. Furthermore, the content of the water-soluble polymer P2 in the polishing composition can be, for example, 1.0 wt% or less. From the viewpoint of obtaining a processing force suitable for the polishing process in which the polishing composition disclosed herein is used, the content of the water-soluble polymer P2 is usually suitably 0.5 wt% or less, preferably 0.1 wt% or less, and may be 0.05 wt% or less, 0.02 wt% or less, or 0.01 wt% or less.

[0102] The total content of the water-soluble polymer in the polishing liquid (the total amount of the water-soluble polymer P1 and other water-soluble polymers used as needed) is not particularly limited, and can be, for example, 0.0001 wt% or more. From the viewpoint of reducing haze lines, the preferred content is 0.0005 wt% or more, more preferably 0.001 wt% or more, for example, 0.003 wt% or more, or even 0.005 wt% or more, 0.008 wt% or more, or even 0.01 wt% or more (for example, more than 0.01 wt%). Furthermore, from the viewpoint of improving the polishing removal rate, the total content of the water-soluble polymer in the polishing liquid is usually preferably 0.2 wt% or less, more preferably 0.1 wt% or less, and may be 0.05 wt% or less (for example, 0.02 wt% or less).

[0103] When a surfactant is contained, the content of the surfactant in the polishing liquid (when two or more surfactants are contained, the total content thereof) is not particularly limited. Typically, the content of the surfactant can be, for example, 0.00001 wt % or more from the viewpoint of cleaning properties, etc. From the viewpoint of improving surface quality (e.g., reducing defects), etc., the content is preferably 0.00005 wt % or more, more preferably 0.0001 wt % or more. In some embodiments, the content may be 0.0002 wt % or more, 0.0005 wt % or more, or 0.0007 wt % or more. Furthermore, from the viewpoint of polishing removal rate, etc., the content is preferably 0.1 wt % or less, more preferably 0.01 wt % or less, and even more preferably 0.005 wt % or less (e.g., 0.003 wt % or less), and may be 0.001 wt % or less, or may be 0.0005 wt % or less.

[0104] <Concentrate> The polishing composition disclosed herein may be in a concentrated form (i.e., in the form of a concentrated polishing liquid) before being supplied to a substrate. Such a concentrated polishing composition is advantageous from the viewpoints of convenience and cost reduction during production, distribution, storage, etc. The concentration ratio is not particularly limited and can be, for example, about 2 to 100 times in volume terms, and typically about 5 to 50 times (e.g., about 10 to 40 times) is appropriate. Such a concentrated liquid can be diluted at a desired time to prepare a polishing liquid (working slurry), which can then be supplied to a substrate. The dilution can be performed, for example, by adding water to the concentrated liquid and mixing.

[0105] When the polishing composition (i.e., concentrate) is diluted and used for polishing, the content of abrasive grains in the concentrate can be, for example, 25% by weight or less. From the viewpoint of the dispersion stability and filterability of the polishing composition, the content is usually preferably 20% by weight or less, more preferably 15% by weight or less. In some preferred embodiments, the content of abrasive grains may be 10% by weight or less, or may be 5% by weight or less. Furthermore, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content of abrasive grains in the concentrate can be, for example, 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 0.7% by weight or more, and even more preferably 1% by weight or more (e.g., more than 1% by weight).

[0106] In some embodiments, the content of the basic compound in the concentrate can be, for example, less than 15 wt%. From the viewpoint of storage stability, etc., the content is usually preferably 10 wt% or less (e.g., less than 10 wt%), more preferably 3 wt% or less, and may be 1 wt% or less (e.g., less than 1 wt%), or even 0.5 wt% or less. Furthermore, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content of the basic compound in the concentrate can be, for example, 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.05 wt% or more, and even more preferably 0.1 wt% or more.

[0107] In some embodiments, the content of acetalized polyvinyl alcohol (water-soluble polymer P1) in the concentrate may be, for example, 0.0005% by weight or more, 0.005% by weight or more, 0.01% by weight or more, 0.05% by weight or more, or 0.1% by weight or more. From the viewpoint of storage stability, the content is suitably, for example, 3.0% by weight or less, 2.0% by weight or less, 1.0% by weight or less, or 0.5% by weight or less.

[0108] When the water-soluble polymer P2 is contained, the content of the water-soluble polymer P2 in the concentrate may be, for example, 0.0005% by weight or more, 0.005% by weight or more, 0.01% by weight or more, 0.05% by weight or more, or 0.1% by weight or more. From the viewpoint of storage stability, the content is suitably, for example, 3.0% by weight or less, 2.0% by weight or less, 1.0% by weight or less, or 0.5% by weight or less.

[0109] The total content of the water-soluble polymer in the concentrate may be, for example, 0.0005% by weight or more, 0.005% by weight or more, 0.01% by weight or more, 0.05% by weight or more, 0.1% by weight or more, or 0.2% by weight or more. From the viewpoint of storage stability, the content is suitably, for example, 5.0% by weight or less, and may be 3.0% by weight or less, 2.0% by weight or less, 1.0% by weight or less, or 0.5% by weight or less.

[0110] In an embodiment in which the polishing composition contains a surfactant, the surfactant content in the concentrate can be, for example, 0.25 wt % or less, preferably 0.15 wt % or less, more preferably 0.1 wt % or less, and may be 0.05 wt % or less, or may be 0.025 wt % or less. The surfactant content in the concentrate can be, for example, 0.0001 wt % or more, preferably 0.001 wt % or more, more preferably 0.005 wt % or more, and even more preferably 0.01 wt % or more.

[0111] <Preparation of Polishing Composition> The polishing composition used in the technology disclosed herein may be a single-component type or a multi-component type such as a two-component type. For example, the polishing composition may be configured to prepare a polishing liquid by mixing Part A containing at least abrasive grains among the components of the polishing composition with Part B containing at least a portion of the remaining components, and then mixing and diluting these at an appropriate timing as needed.

[0112] The method for preparing the polishing composition is not particularly limited. For example, the components constituting the polishing composition may be mixed using a well-known mixing device such as a blade mixer, an ultrasonic disperser, or a homomixer. The manner in which these components are mixed is not particularly limited. For example, all the components may be mixed at once, or may be mixed in an appropriately set order.

[0113] <Applications> The polishing composition of the technology disclosed herein can be used to polish objects of various materials and shapes. The material of the object to be polished can be, for example, metals or semimetals such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, stainless steel, or alloys thereof; glassy materials such as quartz glass, aluminosilicate glass, or glassy carbon; ceramic materials such as alumina, silica, sapphire, silicon nitride, tantalum nitride, or titanium carbide; compound semiconductor substrate materials such as silicon carbide, gallium nitride, or gallium arsenide; or resin materials such as polyimide resin. The object to be polished may be made of a plurality of these materials.

[0114] The polishing composition of the technology disclosed herein can be particularly preferably used for polishing a surface made of silicon (typically, polishing a silicon wafer). A typical example of the silicon wafer referred to here is a silicon single crystal wafer, for example, a silicon single crystal wafer obtained by slicing a silicon single crystal ingot.

[0115] The polishing composition disclosed herein can be preferably applied to a polishing step of an object to be polished (e.g., a silicon wafer). Before the polishing step with the polishing composition disclosed herein, the object to be polished may be subjected to a general treatment that can be applied to an object to be polished in a step upstream of the polishing step, such as lapping or etching.

[0116] The polishing composition disclosed herein is effective when used in the finishing step of a substrate (e.g., a silicon wafer) or in the polishing step immediately preceding it, and is particularly preferably used in the finishing polishing step. Here, the finishing polishing step refers to the final polishing step in the manufacturing process of the object (i.e., a step in which no further polishing is performed after that step). The polishing composition disclosed herein may also be used in a polishing step upstream of the finishing polishing (referring to a preliminary polishing step between the rough polishing step and the final polishing step, which typically includes at least a primary polishing step and may further include secondary, tertiary, etc. polishing steps), for example, a polishing step performed immediately preceding the finishing polishing.

[0117] The polishing composition disclosed herein is effective, for example, for polishing (typically finish polishing or polishing immediately before finish polishing) silicon wafers that have been prepared in an upstream process to have a surface roughness of 0.01 nm to 100 nm. Application to finish polishing is particularly preferred. The surface roughness Ra of the substrate can be measured, for example, using a laser scanning surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement Systems Inc.

[0118] <Polishing> The polishing composition disclosed herein can be used to polish an object to be polished, for example, in an embodiment including the following steps. A preferred embodiment of a method for polishing an object to be polished (e.g., a silicon wafer) using the polishing composition disclosed herein is described below. That is, a polishing liquid containing any of the polishing compositions disclosed herein is prepared. Preparing the polishing liquid may include adjusting the concentration (e.g., diluting), adjusting the pH, or the like of the polishing composition to prepare the polishing liquid. Alternatively, the polishing composition may be used as is as the polishing liquid.

[0119] Next, the polishing liquid is supplied to the object to be polished, and polishing is carried out by a conventional method. For example, when performing finish polishing of a silicon wafer, typically, a silicon wafer that has undergone a lapping process is set in a general polishing device, and the polishing liquid is supplied to the surface of the silicon wafer to be polished through the polishing pad of the polishing device. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface of the silicon wafer to be polished, and the two are moved relatively (for example, rotated). Polishing of the object to be polished is completed through this polishing process.

[0120] The polishing pad used in the polishing step is not particularly limited. For example, a polishing pad of a foamed polyurethane type, a nonwoven fabric type, a suede type, or the like can be used. Each polishing pad may contain abrasive grains or may not contain abrasive grains. Usually, a polishing pad that does not contain abrasive grains is preferably used.

[0121] The object to be polished that has been polished using the polishing composition disclosed herein is typically washed. The washing can be carried out using an appropriate washing liquid. The washing liquid to be used is not particularly limited, and for example, SC-1 washing liquid (ammonium hydroxide (NH ４ OH) and hydrogen peroxide (H ２ O ２ ) and water (H ２ O), SC-2 cleaning solution (HCl and H ２ O ２ and H ２Examples of cleaning solutions that can be used include an ozone water cleaning solution, a mixture of ozone water and ozone water, and a hydrofluoric acid cleaning solution. The temperature of the cleaning solution can be set to, for example, a range from room temperature (typically about 15°C to 25°C) to about 90°C. From the viewpoint of improving the cleaning effect, a cleaning solution of about 50°C to 85°C can be preferably used.

[0122] The matters disclosed in this specification include the following: [1] A polishing composition comprising an abrasive grain, a basic compound, an acetalized polyvinyl alcohol, and water, wherein the acetalized polyvinyl alcohol comprises a unit represented by the following formula (I) and a unit represented by the following formula (II), and the acetalization degree of the acetalized polyvinyl alcohol is greater than 8% and less than 19%. (R １ is a hydrocarbon group. [2] The polishing composition according to [1] above, further comprising a surfactant. [3] The acetalized polyvinyl alcohol has a weight average molecular weight of 3×10 ４ The polishing composition according to [1] or [2] above, which is the following: [4] The polishing composition according to any of [1] to [3] above, further comprising a water-soluble polymer P2 selected from polymers other than acetalized polyvinyl alcohol. [5] The polishing composition according to any of [1] to [4] above, wherein the water-soluble polymer P2 is one or more selected from the group consisting of nitrogen-containing polymers, non-acetalized polyvinyl alcohol-based polymers, polymers containing oxyalkylene units, starch derivatives, and cellulose derivatives. [6] The polishing composition according to any of [1] to [5] above, which contains silica particles as the abrasive grains. [7] A concentrated solution of the polishing composition according to any of [1] to [6] above. [8] A polishing method, comprising polishing a surface made of a silicon material with the polishing composition according to any of [1] to [6] above.

[0123] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" are by weight unless otherwise specified.

[0124] In the following examples, the degree of acetalization (m) of acetalized polyvinyl alcohol was determined by nuclear magnetic resonance (NMR) measurement. The NMR measurement device used was a Bruker model "AVANCE NEO700." The measurement conditions were as follows: [NMR measurement conditions] Observation nucleus: 13C (176.07 MHz) Solvent: light water + heavy water (9:1) Sample concentration: approximately 18% Number of accumulations: 2048 Measurement temperature: room temperature

[0125] Experimental Example 1 Preparation of Polishing Composition Example 1 A concentrated polishing composition according to this example was prepared using abrasive grains, a basic compound, acetalized polyvinyl alcohol (abbreviated as "acetalized PVA" in Table 1), a surfactant, and deionized water. Colloidal silica having an average primary particle size of 25 nm was used as the abrasive grains. Ammonia was used as the basic compound. The acetalized polyvinyl alcohol was a polymer containing a unit (unit (IA)) represented by the above formula (IA) and a unit (unit (II)) represented by the above formula (II), wherein R ２ is a methyl group, the degree of acetalization (m) is 15%, and Mw is 9.0×10 ３ The surfactant used was polyoxyethylene decyl ether (C10EO5) having an ethylene oxide addition mole number of 5. The resulting concentrated polishing composition was diluted 20 times by volume with deionized water to obtain a polishing composition according to this example containing 0.17% abrasive grains, 0.005% basic compound, 0.005% acetalized polyvinyl alcohol, and 0.0002% surfactant.

[0126] (Examples 2 and 3) Acetalized polyvinyl alcohol containing unit (IA) and unit (II), wherein R in the above formula (IA) ２The polishing compositions of each example were prepared in the same manner as in Example 1, except that the was a methyl group and the acetalization degree (m) and Mw were the values ​​shown in Table 1.

[0127] Comparative Example 1 Acetalized polyvinyl alcohol containing units (IA) and (II), ２ is a methyl group, the degree of acetalization (m) is 24%, and Mw is 1.3 × 10 ４ The polishing composition of this example was prepared in the same manner as in Example 1, except that the following was used:

[0128] Comparative Example 2 Acetalized polyvinyl alcohol containing units (IA) and (II), wherein R ２ is a methyl group, the degree of acetalization (m) is 5%, and Mw is 5.8×10 ３ The polishing composition of this example was prepared in the same manner as in Example 1, except that the following was used:

[0129] <Polishing of Silicon Wafers> The details of the pre-stage polishing step applied to each example are shown below. (Pre-stage Polishing Step) A pre-stage polishing composition containing 1.0% abrasive grains, 0.068% basic compound, and the remainder water was prepared. Colloidal silica with an average primary particle size of 35 nm was used as the abrasive grains. Potassium hydroxide (KOH) was used as the basic compound. This pre-stage polishing composition was used as a polishing liquid (working slurry) to polish a silicon wafer as the object to be polished under the pre-stage polishing conditions below. The silicon wafer used was a commercially available silicon single crystal wafer (conductivity type: P-type, crystal orientation: <100>, resistivity: 1 Ω·cm or more and less than 100 Ω·cm, COP-free) with a diameter of 300 mm that had been lapped and etched.

[0130] [Preliminary polishing conditions] Polishing device: Single-fed polishing machine manufactured by Okamoto Machine Tool Works, Ltd., model "PNX-332B" Polishing load: 20 kPa Plate rotation speed: 20 rpm Head (carrier) rotation speed: 20 rpm Polishing pad: Nitta DuPont, product name "SUBA400" Polishing liquid supply rate: 1 liter / min Polishing liquid temperature: 20°C Plate cooling water temperature: 20°C Polishing time: 2 minutes

[0131] (Finish Polishing Step) The polishing composition according to each example was used as a polishing liquid (working slurry) as it was to polish the silicon wafers that had been subjected to the above-mentioned pre-stage polishing step under the following finish polishing conditions.

[0132] [Finish polishing conditions] Polishing device: Single-fed polishing machine manufactured by Okamoto Machine Tool Works, Ltd., model "PNX-332B" Polishing load: 10 kPa Plate rotation speed: 52 rpm Head (carrier) rotation speed: 50 rpm Polishing pad: Polishing pad manufactured by Fujibo Ehime Co., Ltd., product name "POLYPAS27NX" Polishing liquid supply rate: 1.5 liters / minute Polishing liquid temperature: 20°C Plate cooling water temperature: 20°C Polishing time: 4 minutes

[0133] 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.

[0134] <Measurement and Evaluation> (Haze Line) For the silicon wafer after cleaning, a wafer inspection device manufactured by KLA Tencor Corporation, product name "Surfscan SP5", was used to measure the total length T of the haze lines present within a predetermined observation area in the DNO mode of the device. Ｌ The results were used to calculate the total length T ＬThe haze lines were evaluated to be more suppressed as the relative length [%] was set to 100%. The smaller this relative length [%] value, the more the haze lines were suppressed. Based on the relative length, the degree of haze lines was judged according to the following three levels. The results are shown in the corresponding columns in Table 1. A: 0% (no haze lines observed) B: greater than 0% and equal to or less than 100% C: greater than 100%

[0135] (Wettability) When the polished silicon wafer was unloaded, the longest radial distance (water-repellent distance) [mm] of the water-repellent region from the wafer edge was measured. The smaller the water-repellent distance, the better the wettability was evaluated. Based on this water-repellent distance, the wettability level was judged according to the following three criteria. The results are shown in the corresponding column in Table 1. A: Water-repellent distance is 50 mm or less B: Water-repellent distance is greater than 50 mm and less than 100 mm C: Water-repellent distance is 100 mm or more

[0136]

[0137] As shown in Table 1, the polishing compositions of Examples 1 to 3, which used acetalized polyvinyl alcohols with an acetalization degree (m) in the range of more than 8% and less than 19%, were able to maintain a wettability level of B or higher while clearly reducing haze lines compared to the polishing compositions of Comparative Examples 1 and 2. In particular, the polishing compositions of Examples 1 and 2 were able to achieve the effect of reducing haze lines while maintaining good wettability equivalent to or better than that of Comparative Example 2.

[0138] Experimental Example 2 Preparation of Polishing Composition Example 4 Abrasive grains, a basic compound, acetalized polyvinyl alcohol (abbreviated as "acetalized PVA" in Table 2), polyacryloylmorpholine (Mw: 35×10) as the water-soluble polymer P2, and a polishing composition were prepared. ４A concentrated polishing composition according to this example was prepared using 0.17% abrasive grains, 0.005% basic compound, 0.005% acetalized polyvinyl alcohol, 0.007% polyacryloylmorpholine, and 0.001% surfactant. The same abrasive grains, basic compound, acetalized polyvinyl alcohol, and surfactant as in Example 1 were used. The resulting concentrated polishing composition was diluted 20 times by volume with deionized water to obtain a polishing composition according to this example containing 0.17% abrasive grains, 0.005% basic compound, 0.005% acetalized polyvinyl alcohol, 0.007% polyacryloylmorpholine, and 0.001% surfactant.

[0139] (Examples 5 and 6 and Comparative Examples 3 and 4) Polishing compositions for each example were prepared in the same manner as in Example 4, except that the same materials as in Examples 2 and 3 and Comparative Examples 1 and 2 were used as acetalized polyvinyl alcohol.

[0140] <Polishing of Silicon Wafer> In the same manner as in Experimental Example 1, the silicon wafer was polished, washed, and dried.

[0141] <Measurement and Evaluation> (Haze Lines) The total length of the haze lines was measured in the same manner as in Experimental Example 1, and converted into a relative length (%), with the total length of the haze lines in Comparative Example 3 being 100%. Based on this relative length, the degree of haze lines was evaluated using the same three levels as in Experimental Example 1. The results are shown in the corresponding columns in Table 2.

[0142] (Wettability) The water-repellent distance was measured in the same manner as in Experimental Example 1. Based on this water-repellent distance, the wettability level was determined using the same three criteria as in Experimental Example 1. The results are shown in the corresponding columns in Table 2.

[0143]

[0144] As shown in Table 2, it was confirmed that even in compositions further containing the water-soluble polymer P2, the polishing compositions of Examples 4 to 6, which use acetalized polyvinyl alcohol with an acetalization degree (m) in the range of more than 8% and less than 19%, can maintain a wettability level of B or higher while achieving a significant reduction in haze lines compared to the polishing compositions of Comparative Examples 3 and 4. In particular, the polishing compositions of Examples 4 and 5 achieved the effect of reducing haze lines while maintaining good wettability equivalent to or better than that of Comparative Example 4. Although specific values ​​are not shown, the total length T of the haze lines in Comparative Example 3 Ｌ was shorter than that in Comparative Example 1.

[0145] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above.

Claims

1. A polishing composition comprising abrasive grains, a basic compound, acetalized polyvinyl alcohol, and water, wherein the acetalized polyvinyl alcohol comprises a unit represented by the following formula (I) and a unit represented by the following formula (II), and the degree of acetalization of the acetalized polyvinyl alcohol is greater than 8% and less than 19%. (R １ is a hydrocarbon group.

2. The polishing composition according to claim 1, further comprising a surfactant.

3. The polishing composition according to claim 1 or 2, further comprising a water-soluble polymer P2 selected from polymers other than the acetalized polyvinyl alcohol.

4. The polishing composition according to claim 3, wherein the water-soluble polymer P2 is one or more selected from the group consisting of nitrogen atom-containing polymers, non-acetalized polyvinyl alcohol-based polymers, polymers containing oxyalkylene units, starch derivatives, and cellulose derivatives.

5. The polishing composition according to claim 1 or 2, which contains silica particles as the abrasive grains.

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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