Polishing composition and polishing method

Abstract

The present invention provides a polishing composition that is for polishing a surface that comprises a silicon material, the polishing composition giving the surface excellent wettability after polishing and making it possible to reduce defects. Provided is a polishing composition for polishing a surface that comprises a silicon material. The polishing composition contains abrasive grains (A), a basic compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) that has a different chemical structure from the first water-soluble polymer (C1). The first water-soluble polymer (C1) is a random copolymer that includes a vinyl alcohol unit and an N-vinylpyrrolidone unit.

Description

Polishing composition and polishing method

[0001] The present invention relates to a polishing composition. This application claims priority to Japanese Patent Application No. 2023-161703, filed on September 25, 2023, 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 documents 1 and 2 are cited as technical documents related to polishing compositions primarily used for polishing semiconductor substrates such as silicon wafers.

[0003] Japanese Patent No. 6185432 Japanese Patent Application Publication No. 2020-161603

[0004] Polishing compositions used to polish 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, if the substrate is properly protected, it is possible to improve the surface quality after polishing, such as by reducing the haze value. For example, Patent Documents 1 and 2 describe polishing compositions containing colloidal silica, ammonia, and water-soluble polymers such as polyacryloylmorpholine and polyvinyl alcohol, and the reduction of haze value using such polishing compositions has been investigated. On the other hand, if the substrate is not sufficiently protected by the water-soluble polymer, defects will occur on the polished surface, which will be detected, for example, as light point defects (LPDs). Furthermore, if residues of the water-soluble polymer remain on the polished substrate surface, they will be detected as particles during surface inspection of the substrate, which can also contribute to an increase in LPDs. For this reason, in polishing using a polishing composition containing a water-soluble polymer, whether or not the surface has high quality is evaluated by checking the degree of reduction in defects (e.g., LPDs) on the substrate surface after polishing.

[0005] Furthermore, in order to obtain a high-quality surface, it is preferable that the polished silicon wafer surface has sufficient wettability. By keeping the polished surface wet with water (with a water film attached), it is possible to prevent foreign matter and the like from directly adhering to the polished surface. A silicon wafer surface having such a surface is likely to obtain a higher-quality surface after cleaning.

[0006] The present invention was created in consideration of the above circumstances, and aims to provide a polishing composition that can be used to polish a surface made of a silicon material, has excellent wettability on the surface after polishing, and can reduce defects.

[0007] According to the present specification, there is provided a polishing composition for use in polishing a surface made of a silicon material. The polishing composition comprises abrasive grains (A), a basic compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) having a chemical structure different from that of the first water-soluble polymer (C1). The first water-soluble polymer (C1) is a random copolymer containing vinyl alcohol units and N-vinylpyrrolidone units. The polishing composition provides excellent wettability to the surface made of a silicon material after polishing, and reduces defects on the surface.

[0008] In some embodiments, the second water-soluble polymer (C2) is at least one selected from the group consisting of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers, polymers containing nitrogen atoms, and carboxylic acid-based polymers. By using the second water-soluble polymer (C2) selected from the above types in combination with the first water-soluble polymer (C1), excellent wettability and reduced defects are preferably achieved.

[0009] In some embodiments, the ratio of the content of the second water-soluble polymer (C2) to the content of the first water-soluble polymer (C1) is, by weight, from 0.1 to 20. In embodiments in which the first water-soluble polymer (C1) and the second water-soluble polymer (C2) are used in the above ratio, the effects of the technology disclosed herein can be preferably achieved.

[0010] In some embodiments, the weight average molecular weight of the first water-soluble polymer (C1) is 2×10 ４ By using the first water-soluble polymer (C1) having the above weight-average molecular weight, excellent wettability and reduced defects are preferably achieved.

[0011] In some embodiments, the polishing composition contains silica particles as the abrasive grains (A). 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 further comprises a surfactant (D). According to such a configuration, the surface quality after polishing tends to be further improved.

[0013] The polishing composition disclosed herein can be a concentrate. The polishing composition disclosed herein can be manufactured, distributed, and stored as a concentrate.

[0014] In some embodiments, a polishing method is provided, comprising the step of polishing a surface of a silicon material with the polishing composition, whereby the polished surface of the silicon material has excellent wettability and reduced defects.

[0015] 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.

[0016] <Abrasive Grains (A)> The polishing composition disclosed herein contains abrasive grains. The abrasive grains contribute to improving the polishing rate by mechanically polishing 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 mode of use of the polishing composition. Examples of abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of inorganic particles include 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; and carbonates such as calcium carbonate and barium carbonate. Specific examples of organic particles include polymethyl methacrylate (PMMA) particles, poly(meth)acrylic acid particles (here, (meth)acrylic acid refers collectively to acrylic acid and methacrylic acid), polyacrylonitrile particles, etc. Such abrasive grains may be used alone or in combination of two or more types.

[0017] 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. In polishing compositions that can be used for polishing (e.g., finish polishing) objects having a silicon surface, such as silicon wafers, it is particularly useful to employ silica particles as the abrasive grains. The technology disclosed herein can be preferably implemented, for example, in an embodiment in which substantially only silica particles are used as the abrasive grains. From this perspective, the proportion of silica particles in the total amount of abrasive grains is suitably 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more (e.g., 99 to 100% by weight).

[0018] 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.

[0019] 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.

[0020] 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 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. From the viewpoint of easily obtaining a surface with a lower haze, in some embodiments, the average primary particle diameter of the abrasive grains may be 43 nm or less, may be less than 40 nm, may be less than 38 nm, may be less than 35 nm, may be less than 32 nm, or may be less than 30 nm.

[0021] In this specification, the average primary particle diameter is calculated from the specific surface area (BET value) measured by the BET method by the following formula: average primary particle diameter (nm) = 6000 / (true density (g / cm ３ ) × BET value (m ２ The specific surface area is the particle size (BET particle size) calculated by the formula: (1 / g / 2) / (2 / g). The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritics, trade name "Flow Sorb II 2300."

[0022] 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 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.

[0023] 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.

[0024] The shape (external shape) of the abrasive grains (typically silica particles) 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, silica particles in which most of the particles are peanut-shaped or cocoon-shaped can be preferably used.

[0025] Although not particularly limited, the average value of the long axis / short axis ratio (average aspect ratio) of the abrasive grains (typically silica particles) 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 rate can be achieved. Furthermore, from the viewpoint of reducing scratches, etc., the average aspect ratio of the abrasive grains (typically silica particles) 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.

[0026] The shape (external shape) and average aspect ratio of abrasive grains (typically silica particles) 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 (abrasive particles, typically silica particles) whose individual particle shapes can be recognized. Then, for each rectangle drawn for each particle image, the long side length (long diameter value) is divided by the short side length (short diameter value) to calculate the long diameter / short diameter ratio (aspect ratio). The average aspect ratio can be determined by arithmetically averaging the aspect ratios of the predetermined number of particles.

[0027] <Basic Compound (B)> The polishing composition disclosed herein contains a basic compound. In this specification, a basic compound refers to a compound that dissolves in water and increases the pH of the aqueous solution. By incorporating a basic compound into the polishing composition, the polishing target can be efficiently polished by its chemical polishing action (alkaline etching). Examples of basic compounds that can be used include nitrogen-containing organic or inorganic basic compounds, phosphorus-containing basic compounds, alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates and bicarbonates, etc. Examples of nitrogen-containing basic compounds include quaternary ammonium compounds, ammonia, amines (preferably water-soluble amines), etc. Examples of phosphorus-containing basic compounds include quaternary phosphonium compounds. These basic compounds can be used alone or in combination of two or more.

[0028] 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.

[0029] As the quaternary ammonium compound, a quaternary ammonium salt (typically a strong base) such as a tetraalkylammonium salt or a hydroxyalkyltrialkylammonium salt can be used. The anion component in such a quaternary ammonium salt is, for example, OH － , F－ , Cl － ,Br － , I － , ClO ４ － , B.H. ４ － Examples of the quaternary ammonium compounds include those 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.

[0030] 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, tetraalkylammonium hydroxides (e.g., tetramethylammonium hydroxide) and ammonia are more preferred, and ammonia is particularly preferred.

[0031] <Water-soluble polymer (C)> The polishing composition disclosed herein contains at least two water-soluble polymers. In other words, the polishing composition disclosed herein contains a first water-soluble polymer (C1) and a second water-soluble polymer (C2). Specifically, by using the first water-soluble polymer (C1) and the second water-soluble polymer (C2) described below in combination, the advantages based on the different actions of each water-soluble polymer can be enjoyed, and the polished surface can have excellent wettability and reduce defects on the surface.

[0032] <First Water-Soluble Polymer (C1)> The first water-soluble polymer is a random copolymer containing vinyl alcohol units (hereinafter also referred to as "VA units") and N-vinylpyrrolidone units (hereinafter also referred to as "VP units"). Here, the VA units are units having the following chemical formula: -CH２ The VA unit is a structural unit (repeating unit) represented by -CH(OH)-. VA units are obtained, for example, by hydrolysis (also known as saponification) of structural units formed by vinyl polymerization of vinyl ester monomers such as vinyl acetate. VP units are structural units derived from N-vinylpyrrolidone as a monomer in one molecule of the random copolymer. The first water-soluble polymer can be obtained, for example, by partial or complete saponification of a random copolymer of vinyl acetate and N-vinylpyrrolidone. Use of a first water-soluble polymer having the above chemical structure can provide excellent protection for the polished surface while providing excellent wettability to the polished surface. The first water-soluble polymer may be used alone, or two or more different types having different molar ratios of VA units and VP units or two or more different Mws may be used in combination.

[0033] The molar ratio (VA / VP) of VA units to VP units in the first water-soluble polymer is not particularly limited. The molar ratio (VA / VP) can be set within an appropriate range so that the polymer functions as a random copolymer. In some embodiments, the molar ratio (VA / VP) may be, for example, 50 / 50 or more, 65 / 35 or more, 70 / 30 or more, 75 / 25 or more, 80 / 20 or more, 85 / 15 or more, or 90 / 10 or more (e.g., greater than 90 / 10). In some embodiments, the molar ratio (VA / VP) may be, for example, 99 / 1 or less, 98 / 2 or less, 97 / 3 or less, 95 / 5 or less, or 93 / 7 or less.

[0034] The weight-average molecular weight (Mw) of the first water-soluble polymer is not particularly limited. A random copolymer containing VA units and VP units can provide sufficient wettability whether the molecular weight is small or large. Although not particularly limited, in some embodiments, the Mw of the first water-soluble polymer is, for example, 100 × 10 ４ It can be 60×10 ４ In some preferred embodiments, from the viewpoint of concentration efficiency, the Mw is 30×10 ４or less, for example, 20×10 ４ It may be 10×10 or less. ４ Less than 8 x 10 is also acceptable. ４ Less than 5 × 10 ４ Less than 3 × 10 ４ As the Mw decreases, the dispersion stability of the first water-soluble polymer tends to improve. ４ It is preferable that the value is equal to or less than 1.8×10 ４ It may be 1.5 × 10 or less, ４ Less than (e.g., 1.5 x 10 ４ By using a first water-soluble polymer having an Mw in the above range, excellent wettability and reduced defects can be preferably achieved. In addition, from the viewpoint of improving wettability after polishing while suitably protecting the polished surface, in some embodiments, the Mw may be, for example, 0.2 × 10 ４ or more, and may be 0.25 × 10 ４ or more, 0.3 × 10 ４ or more, 0.5 × 10 ４ or more, 0.8 × 10 ４ As the Mw of the first water-soluble polymer increases, the effect of improving the protection of the object to be polished tends to increase. From this viewpoint, in some preferred embodiments, the Mw is 1.0 × 10 ４ or more (for example, 1.0 × 10 ４ (over 1.5 × 10 ４ or more, and may be 1.8 × 10 ４ or more, 2.0 × 10 ４ or more (e.g., 2.0 × 10 ４ (over 2.3 × 10 ４ or more, 2.5 × 10 ４ or more, 2.8 × 10 ４ More than that is fine.

[0035] The Mw of the water-soluble polymer can be a molecular weight calculated from a value based on aqueous gel permeation chromatography (GPC) (aqueous, polyethylene oxide equivalent). The same applies to the Mw of the first water-soluble polymer described above and the second water-soluble polymer described below. As a GPC measuring device, it is recommended to use a model "HLC-8320GPC" manufactured by Tosoh Corporation. Measurement can be carried out, for example, under the following conditions. The same method is also used in the examples described below. [GPC measurement conditions] Sample concentration: 0.1 wt% Column: TSKgel GMPW ＸＬ Detector: differential refractometer Eluent: 100 mM sodium nitrate aqueous solution Flow rate: 1 mL / min Measurement temperature: 40°C Sample injection volume: 200 μL

[0036] Although not particularly limited, in some embodiments, the content of the first water-soluble polymer in the polishing composition can be, for example, 0.01 parts by weight or more per 100 parts by weight of abrasive grains (typically silica particles). From the viewpoint of improving wettability, 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 part by weight or more, and may be 1.5 parts by weight or more, or may be 2 parts by weight or more. The content of the first water-soluble polymer 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 dispersion stability of the polishing composition, etc., in some embodiments, the content of the first water-soluble polymer per 100 parts by weight of abrasive grains is appropriate to be 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and may be less than 3 parts by weight, or may be 2.5 parts by weight or less. By appropriately setting the amount of the first water-soluble polymer used within the above range, it is possible to achieve a surface with excellent wettability after polishing while suitably protecting the polished surface.

[0037] <Second Water-Soluble Polymer (C2)> The polishing composition disclosed herein contains a second water-soluble polymer in addition to the first water-soluble polymer. The second water-soluble polymer has a different chemical structure from the first water-soluble polymer. As the second water-soluble polymer, it is preferable to use one or more water-soluble polymers selected from water-soluble polymers other than random copolymers containing VA units and VP units. By using the first water-soluble polymer and the second water-soluble polymer in combination, the surface of the object to be polished can be suitably protected and defects can be reduced.

[0038] Examples of the second water-soluble polymer include compounds containing a hydroxyl group, a carboxyl group, an acyloxy group, a sulfo group, an amide structure, an imide structure, a quaternary ammonium structure, a heterocyclic structure, a vinyl structure, or the like in the molecule. Examples of the second water-soluble polymer include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers, polymers containing nitrogen atoms, and carboxylic acid-based polymers. The second water-soluble polymer may be a polymer derived from a natural product or a synthetic polymer.

[0039] In some embodiments, the second water-soluble polymer is a polymer derived from natural sources, such as cellulose derivatives and starch derivatives.

[0040] In some preferred embodiments, a cellulose derivative is used as the second water-soluble polymer. Here, the cellulose derivative is a polymer 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.

[0041] In some embodiments, the second water-soluble polymer is a starch derivative, which is a polymer containing α-glucose units as the main repeating unit, such as pregelatinized starch, pullulan, carboxymethyl starch, and cyclodextrin.

[0042] In some preferred embodiments, a synthetic polymer is used as the second water-soluble polymer, and the surface quality improving effect disclosed herein is preferably exhibited in embodiments in which a synthetic polymer is used as the second water-soluble polymer.

[0043] In some embodiments, a polymer containing an oxyalkylene unit is used as the second water-soluble polymer. Examples of polymers containing an oxyalkylene unit 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 containing a PEO block and a polypropylene oxide (PPO) block, or a triblock copolymer. 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.

[0044] 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.

[0045] 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.

[0046] In some embodiments, the second water-soluble polymer may include a polyvinyl alcohol-based polymer. The polyvinyl alcohol-based polymer used as the second water-soluble polymer refers to a polymer containing VA units as its repeating units, and does not include random copolymers containing VA units and VP units. The polyvinyl alcohol-based polymer 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, a block copolymer, an alternating 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.

[0047] The polyvinyl alcohol-based polymer may be either unmodified polyvinyl alcohol (unmodified PVA) or modified polyvinyl alcohol (modified PVA). Here, unmodified PVA is a polymer produced by hydrolysis (saponification) of polyvinyl acetate, and has a repeating unit (-CH ２ -CH(OCOCH ３ )-) and a polyvinyl alcohol-based polymer that is substantially free of repeating units other than VA units. The degree of saponification of the unmodified PVA may be, for example, 60% or more, and from the viewpoint of water solubility, may be 70% or more, 80% or more, or 90% or more. In some embodiments, the degree of saponification of the unmodified PVA may be 98% or more (complete saponification).

[0048] The polyvinyl alcohol-based polymer may be a modified PVA containing VA units and non-VA units having at least one structure selected from 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. Non-VA units that may be contained in the modified PVA include, but are not limited to, repeating units derived from N-vinyl monomers or N-(meth)acryloyl monomers, as described below, repeating units derived from ethylene, repeating units derived from alkyl vinyl ethers, repeating units derived from vinyl esters of monocarboxylic acids having 3 or more carbon atoms, and repeating units derived from (di)acetone compounds. An example of the N-vinyl monomer is N-vinylpyrrolidone. An 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.

[0049] In some embodiments, an acetalized polyvinyl alcohol polymer is used as the polyvinyl alcohol polymer. An example of an acetalized polyvinyl alcohol polymer is a modified PVA in which a portion of the VA units contained in the polyvinyl alcohol polymer have been acetalized. The modified PVA in which a portion of the VA units contained in the polyvinyl alcohol polymer have been acetalized (acetalized PVA (ac-PVA)) can be obtained by reacting a portion of the hydroxy groups of the polyvinyl alcohol polymer with an aldehyde compound or a ketone compound to acetalize the polymer. Typically, the acetalized polyvinyl alcohol polymer is obtained by the acetalization reaction of a polyvinyl alcohol polymer with an aldehyde compound. In some embodiments, the aldehyde compound has 1 to 7 carbon atoms, for example, 2 to 7 carbon atoms.

[0050] Examples of the aldehyde compound include formaldehyde; linear or branched alkyl aldehydes such as acetaldehyde, propionaldehyde, n-butylaldehyde, isobutyraldehyde, t-butylaldehyde, and hexylaldehyde; and alicyclic or aromatic aldehydes such as cyclohexanecarbaldehyde and benzaldehyde. These may be used alone or in combination of two or more. Furthermore, with the exception of formaldehyde, one or more hydrogen atoms may be substituted with a halogen or the like. Among these, linear or branched alkyl aldehydes may be used, such as acetaldehyde, n-propylaldehyde, n-butylaldehyde, and n-pentylaldehyde, because they have high solubility in water and are easily acetalized.

[0051] In addition to the above, aldehyde compounds having 8 or more carbon atoms such as 2-ethylhexylaldehyde, nonylaldehyde, and decylaldehyde may also be used as the aldehyde compound.

[0052] Acetalized polyvinyl alcohol-based polymers have the following chemical formula: -CH ２The copolymer contains a VA unit, which is a structural moiety represented by —CH(OH)—; and an acetalized structural unit (hereinafter also referred to as a “VAC unit”) represented by the following general formula (1):

[0053] (In formula (1), R is a hydrogen atom or a linear or branched alkyl group, and the alkyl group may be substituted with a functional group.)

[0054] In some embodiments, R in the above formula (1) is a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms. R may be one of these groups or a combination of two or more of these groups. From the viewpoint of improving haze reduction performance, R may be a linear or branched alkyl chain having 1 to 6 carbon atoms.

[0055] From the viewpoint of improving haze reduction performance, the acetalization degree of the acetalized polyvinyl alcohol-based polymer can be 1 mol% or more, or may be 5 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, or 25 mol% or more (e.g., 27 mol% or more). From the viewpoint of improving hydrophilicity, the acetalization degree of the acetalized polyvinyl alcohol-based polymer may be less than 60 mol%, or may be 50 mol% or less, 40 mol% or less, or may be 35 mol% or less (e.g., 33 mol% or less). In this specification, the "acetalization degree" refers to the proportion of acetalized structural units (VAC units) in all repeating units constituting the acetalized polyvinyl alcohol-based polymer.

[0056] Furthermore, as the polyvinyl alcohol-based polymer, a cation-modified polyvinyl alcohol into which a cationic group such as a quaternary ammonium structure has been introduced may be used. Examples of the cation-modified polyvinyl alcohol include those into which a cationic group derived from a monomer having a cationic group, such as a diallyldialkylammonium salt or an N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salt, has been introduced. Furthermore, as the vinyl alcohol-based polymer, a non-VA unit having the chemical formula: -CH ２ -CH(CR １ (OR ４)-CR ２ (OR ５ )-R ３ )-, where R １ ~R ３ each independently represents a hydrogen atom or an organic group, R ４ and R ５ are each independently a hydrogen atom or R ６ -CO- (wherein, R ６ represents an alkyl group. For example, R １ ~R ３ When at least one of R is an organic group, the organic group may be a linear or branched alkyl group having 1 to 8 carbon atoms. ６ can be a linear or branched alkyl group having from 1 to 8 carbon atoms.

[0057] In some embodiments, the modified PVA used is a modified PVA having a 1,2-diol structure in a side chain. １ ~R ５ A modified PVA (butenediol-vinyl alcohol copolymer (BVOH)) containing a non-VA unit in which is a hydrogen atom can be preferably used.

[0058] 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.

[0059] 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.

[0060] 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).

[0061] 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.

[0062] 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.

[0063] 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 some embodiments, a polyvinyl alcohol-based polymer having a structure in which polymer chain B is grafted to polymer chain A can be used.

[0064] Examples of polymer chain B include polymer chains having a repeating unit derived from an N-vinyl type monomer as the main repeating unit, polymer chains having a repeating unit derived from an N-(meth)acryloyl type monomer as the main repeating unit, polymer chains having a repeating unit derived from a vinyl dicarboxylate such as fumaric acid, maleic acid, or maleic anhydride as the main repeating unit, polymer chains having a repeating unit derived from an aromatic vinyl monomer such as styrene or vinylnaphthalene as the main repeating unit, and polymer chains having an oxyalkylene unit as the main repeating unit. In this specification, unless otherwise specified, the term "main repeating unit" refers to a repeating unit contained in an amount of more than 50% by weight.

[0065] 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.

[0066] In this specification, 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.

[0067] 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.

[0068] In this specification, examples of N-(meth)acryloyl type monomers include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of 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.

[0069] 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.

[0070] 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, a block copolymer, an alternating copolymer, or a graft copolymer of the corresponding alkylene oxides.

[0071] 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 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.

[0072] In some embodiments, the polyvinyl alcohol-based polymer used as the second water-soluble polymer may be a modified polyvinyl alcohol, which is a copolymer containing VA units and non-VA units. The degree of saponification of the modified polyvinyl alcohol-based polymer used as the second water-soluble polymer is usually 50 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, for example, 75 mol% or more.

[0073] In some other embodiments, a polyvinyl alcohol-based polymer may not be used as the second water-soluble polymer. The technology disclosed herein can be preferably implemented in an embodiment in which the second water-soluble polymer is substantially free of a polyvinyl alcohol-based polymer. For example, the proportion of the polyvinyl alcohol-based polymer in the entire second water-soluble polymer may be 50% by weight or less (e.g., less than 50% by weight), 30% by weight or less, 20% by weight or less, 10% by weight or less, or 5% by weight or less (e.g., 0 to 5% by weight).

[0074] In some preferred embodiments, a nitrogen atom-containing polymer is used as the second water-soluble polymer. A polishing composition containing a nitrogen atom-containing polymer is likely to produce a high-quality polished surface. The nitrogen atom-containing polymer is typically a polymer containing a repeating unit derived from a monomer having a nitrogen atom (a repeating unit containing a nitrogen atom). Non-limiting examples of the nitrogen atom-containing polymer include a polymer containing an N-vinyl type monomer unit; a polymer containing an N-(meth)acryloyl type monomer unit; and the like. One type of nitrogen atom-containing polymer may be used alone, or two or more types may be used in combination.

[0075] In some preferred embodiments, an N-vinyl polymer can be used as the second water-soluble polymer. Examples of N-vinyl polymers include polymers containing repeating units derived from monomers having a nitrogen-containing heterocycle (e.g., a lactam ring). Examples of such polymers include homopolymers and copolymers of N-vinyl lactam monomers (e.g., copolymers in which the copolymerization ratio of N-vinyl lactam monomers exceeds 50% by 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.

[0076] 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.), block copolymers, alternating copolymers, and graft copolymers containing polymer chains containing one or both of VP and VC. Specific examples of N-vinyl linear amides include N-vinylacetamide, N-vinylpropionic acid amide, and N-vinylbutyric acid amide.

[0077] In some preferred embodiments, an N-vinyl linear amide polymer is used as the second water-soluble polymer. Here, the term "N-vinyl linear amide polymer" refers to a homopolymer or copolymer (e.g., a copolymer in which the copolymerization ratio of N-vinyl linear amide exceeds 50% by weight) of an N-vinyl linear amide (e.g., N-vinylacetamide). By using an N-vinyl linear amide polymer as the second water-soluble polymer, a more excellent defect reduction effect is likely to be obtained. The content of repeating units derived from N-vinyl linear amide in the N-vinyl linear amide polymer is typically greater than 50% by weight, and may be 70% by weight or more, 85% by weight or more, or even 95% by weight or more. Substantially all of the N-vinyl linear amide polymer may be composed of repeating units derived from N-vinyl linear amide. A typical example of an N-vinyl linear amide polymer is poly-N-vinylacetamide (PNVA).

[0078] In some embodiments, an N-(meth)acryloyl polymer may be used as the second water-soluble polymer. Examples of N-(meth)acryloyl polymers include homopolymers and copolymers of N-(meth)acryloyl monomers (typically copolymers in which the copolymerization ratio of N-(meth)acryloyl monomers exceeds 50% by weight). Examples of N-(meth)acryloyl monomers include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. N-(meth)acryloyl polymers (e.g., polymers containing cyclic amides having an N-(meth)acryloyl group as monomer units) can protect the substrate surface while better demonstrating the effect of containing the first water-soluble polymer (wettability improvement effect). Note that, in this specification, "(meth)acryloyl" refers collectively to acryloyl and methacryloyl types. In this specification, the term "(meth)acryloyl group" refers to an acryloyl group and a methacryloyl group inclusively.

[0079] 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). In this specification, the term "(meth)acrylamide" refers to acrylamide and methacrylamide in a comprehensive sense.

[0080] 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). All repeating units of the second water-soluble polymer may be substantially composed of ACMO units.

[0081] In some embodiments, a carboxylic acid polymer is used as the second water-soluble polymer. 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 refers collectively to acrylic acid and methacrylic acid.

[0082] In some embodiments, a random copolymer containing VA units and VP units can be used as the second water-soluble polymer. In this case, a random copolymer having a different chemical structure from that of the first water-soluble polymer is used as the second water-soluble polymer. For example, a copolymer having a different molar ratio of VA units to VP units from that of the first water-soluble polymer may be used, or a copolymer having a different Mw from that of the first water-soluble polymer may be used.

[0083] Although not particularly limited, the technology disclosed herein is preferably implemented in an embodiment in which the second water-soluble polymer is one or more selected from cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and carboxylic acid polymers. The second water-soluble polymer is preferably selected from cellulose derivatives, polymers containing oxyalkylene units, and polymers containing nitrogen atoms, and more preferably selected from cellulose derivatives and polymers containing nitrogen atoms. For example, in an embodiment in which the second water-soluble polymer is one or more selected from cellulose derivatives, starch derivatives, polymers containing an oxyalkylene unit, polymers containing a nitrogen atom, and carboxylic acid polymers (e.g., polymers containing a nitrogen atom), the proportion of the one or more selected from cellulose derivatives, starch derivatives, polymers containing an oxyalkylene unit, polymers containing a nitrogen atom, and carboxylic acid polymers (e.g., polymers containing a nitrogen atom) in the entire second water-soluble polymer may be 50% by weight or more (e.g., more than 50% by weight), 70% by weight or more, 80% by weight or more, 90% by weight or more, or 95% by weight or more (e.g., 95 to 100% by weight).

[0084] The Mw of the second water-soluble polymer is not particularly limited. In some embodiments, the Mw of the second water-soluble polymer is, for example, about 200×10 ４ It may be less than or equal to approximately 100×10 ４ Less than 70 x 10 ４ Less than 60 x 10 ４ Less than 50 x 10 ４ Less than 40 x 10 ４ Less than 30 x 10 ４ In order to improve the surface quality, in some embodiments, the Mw may be, for example, 0.5 × 10 or less. ４ or more, and may be 1×10 ４ More than 5 x 10 ４ More than 8 x 10 is also acceptable. ４ or more (e.g., 8 x 10 ４In some preferred embodiments, the Mw is 10×10 ４ The above is appropriate, 15 x 10 ４ or more, 20 × 10 ４ or more, 25 × 10 ４ More than 30 x 10 ４ or more (e.g., 30 x 10 ４ By using a second water-soluble polymer with a high Mw, high surface quality tends to be easily obtained.

[0085] Although not particularly limited, in some embodiments, the technology disclosed herein can be preferably implemented in an embodiment in which a first water-soluble polymer having a relatively small Mw is combined with a second water-soluble polymer having a relatively large Mw. In some preferred embodiments, the ratio (Mw1 / Mw2) of the Mw of the first water-soluble polymer (Mw1) to the Mw of the second water-soluble polymer (Mw2) is less than 1, or may be 0.7 or less, 0.5 or less (e.g., less than 0.5), 0.3 or less, 0.2 or less, or 0.1 or less. From the viewpoint of further improving wettability after polishing while favorably protecting the polished surface, the ratio (Mw1 / Mw2) is preferably 0.08 or less, and may be 0.05 or less (e.g., less than 0.05 or 0.04 or less). In some embodiments, the ratio (Mw1 / Mw2) may be 0.001 or more, 0.005 or more, 0.008 or more, 0.01 or more, 0.05 or more, or 0.07 or more.

[0086] Although not particularly limited, in some embodiments, the content of the second water-soluble polymer in the polishing composition can be, for example, 0.01 parts by weight or more per 100 parts by weight of abrasive grains (typically silica particles). From the viewpoint of reducing defects, 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 part by weight or more, even more preferably 2 parts by weight or more, or even 2.5 parts by weight or more, or even 3 parts by weight or more. Furthermore, the content of the second water-soluble polymer per 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, or even 30 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of the second water-soluble polymer per 100 parts by weight of abrasive grains is appropriate to be 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, for example, 4.5 parts by weight or less, 4.0 parts by weight or less, or even 3.5 parts by weight or less. By appropriately setting the amount of the second water-soluble polymer used within the above range, high surface quality can be obtained.

[0087] Although not particularly limited, in some embodiments, the ratio (B / C) of the content of the basic compound (B) to the total content (total amount; C) of the water-soluble polymer in the polishing composition can be, for example, 0.01 or more by weight. From the viewpoint of the polishing rate, etc., it is appropriate to set it to 0.1 or more, preferably 0.2 or more, more preferably 0.5 or more, and may be 0.7 or more. In some embodiments, the ratio (B / C) may be, for example, 15 or less by weight, or may be 10 or less. In addition, from the viewpoint of suitably protecting the polishing surface and maintaining or improving surface quality, the ratio (B / C) is suitably 7 or less, preferably 5 or less, more preferably 2 or less, and may be, for example, 1.5 or less. By appropriately setting the total content of the water-soluble polymer and the basic compound so that the ratio (B / C) is within the above range, high surface quality can be obtained.

[0088] Although not particularly limited, in some embodiments, the total content (total amount) of the water-soluble polymers contained in the polishing composition can be, for example, 0.01 parts by weight or more relative to 100 parts by weight of abrasive grains (typically silica particles). From the viewpoint of improving surface quality, 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 part by weight or more, even more preferably 2 parts by weight or more, particularly preferably 3 parts by weight or more, even 4 parts by weight or more, or even 5 parts by weight or more. Furthermore, the total content of the water-soluble polymers relative to 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 relative to 100 parts by weight of abrasive grains is appropriate to set it to 15 parts by weight or less, preferably 12 parts by weight or less, or may be 10 parts by weight or less (for example, less than 10 parts by weight).

[0089] Although not particularly limited, in some embodiments, the ratio (W2 / W1) of the content W2 of the second water-soluble polymer to the content W1 of the first water-soluble polymer is, for example, 0.01 or more by weight, suitably 0.1 or more, preferably 0.2 or more, and may be 0.4 or more, 0.6 or more, or 0.8 or more. In some preferred embodiments, the ratio (W2 / W1) may be 1.0 or more, 1.2 or more, or 1.4 or more. Furthermore, in some embodiments, the upper limit of the ratio (W2 / W1) is, for example, 30 or less by weight, suitably 20 or less, 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less. In some preferred embodiments, the ratio (W2 / W1) is suitably 5 or less, preferably 3 or less, or may be 2 or less (e.g., less than 2). By appropriately setting the ratio (W2 / W1) within the above range, the effects of the technology disclosed herein can be favorably exhibited.

[0090] <Surfactant (D)> In some embodiments, the polishing composition preferably contains a surfactant. By including a surfactant in the polishing composition, defects and haze on the polished surface can be more effectively reduced. According to the technology disclosed herein, a composition containing the above-mentioned combination of water-soluble polymers and 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. Usually, anionic or nonionic surfactants can be preferably used. From the viewpoints of low foaming and ease of pH adjustment, nonionic surfactants are more preferred. The use of a nonionic surfactant tends to further improve defect reduction performance and haze reduction performance. Examples of nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene derivatives (e.g., polyoxyalkylene adducts) such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; and copolymers of multiple types of oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). One surfactant may be used alone, or two or more may be used in combination.

[0091] 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.

[0092] 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). In addition, from the viewpoint of surface activity and the like, the molecular weight of the surfactant is usually appropriate to be 200 or more, and from the viewpoint of haze reduction effect and the like, it is preferably 250 or more (e.g., 300 or more).

[0093] 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.

[0094] The molecular weight of the surfactant may be the molecular weight calculated from the chemical formula, or the weight average molecular weight (water-based, polyethylene glycol equivalent) determined by GPC. 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 GPC.

[0095] 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. 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 0.1 parts by weight or more, and may be 0.3 parts by weight or more.

[0096] Although not particularly limited, in an embodiment in which the polishing composition contains a surfactant, the ratio (D / C) of the surfactant content (D) to the total content (C) of the water-soluble polymers can be, for example, 0.001 or more by weight, and from the viewpoint of defect reduction, 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. Furthermore, in some embodiments, the ratio (D / C) can be, for example, 10 or less by weight, and from the viewpoint of defect reduction, etc., it is appropriate to set it to 1 or less (for example, less than 1), preferably 0.5 or less, more preferably 0.3 or less, and may be, for example, 0.15 or less, or may be 0.10 or less.

[0097] <Water> The water contained in the polishing composition disclosed herein can preferably be ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, or the like. 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 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, or by distillation, among other procedures. The polishing composition disclosed herein may further contain an organic solvent (e.g., a lower alcohol or a lower ketone) that is uniformly miscible with water, as needed. Preferably, 90% by volume or more of the solvent contained in the polishing composition is water, and more preferably 95% by volume or more (e.g., 99 to 100% by volume) is water.

[0098] <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.

[0099] 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.

[0100] 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.

[0101] 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 rate. Specific examples of the oxidizing agent 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.

[0102] <pH> The pH of the polishing composition disclosed herein is not particularly limited, and an appropriate pH can be adopted depending on the substrate, etc. In some embodiments, the pH of the polishing composition is suitably 8.0 or higher, preferably 8.5 or higher, more preferably 9.0 or higher. As the pH of the polishing composition increases, the polishing rate tends to improve. On the other hand, from the viewpoint of preventing dissolution of silica particles and suppressing a decrease in mechanical polishing action, the pH of the polishing composition is usually suitably 12.0 or lower, preferably 11.0 or lower, more preferably 10.8 or lower, and even more preferably 10.5 or lower.

[0103] 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.

[0104] <Polishing Liquid> The polishing composition disclosed herein is typically supplied to the surface of a substrate in the form of a polishing liquid containing the polishing composition, and is used to polish the substrate. The polishing liquid can be prepared, for example, by diluting any of the polishing compositions disclosed herein (typically with water). Alternatively, the polishing composition can 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.

[0105] The content of abrasive grains (typically silica particles) in the polishing liquid is not particularly limited, and is, for example, 0.005 wt% or more, preferably 0.01 wt% or more, more preferably 0.03 wt% or more, even more preferably 0.05 wt% or more, and may be 0.08 wt% or more, or even 0.10 wt% or more (e.g., greater than 0.10 wt%). By increasing the abrasive grain content, a higher polishing rate can be achieved. The content is suitably 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, 0.5 wt% or less, 0.4 wt% or less, or 0.3 wt% or less. This makes it easier to maintain surface quality.

[0106] The content of the basic compound in the polishing liquid is not particularly limited. From the viewpoint of improving the polishing rate, etc., it is usually appropriate for the content to be 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 surface quality (e.g., reducing haze), etc., it is appropriate for the content to be less than 0.1 wt %, 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 %).

[0107] Although not particularly limited, in some embodiments, the content W1 of the first water-soluble polymer (specifically, a random copolymer containing VA units and VP units) in the polishing liquid may be, for example, 0.0001 wt % or more, typically 0.0005 wt % or more, and preferably 0.001 wt % or more, from the viewpoint of improving wettability, etc., and may be, for example, 0.002 wt % or more, or even 0.0025 wt % or more. The upper limit of the content W1 of the first water-soluble polymer is not particularly limited, and may be, for example, 0.05 wt % or less. From the viewpoint of stability at the concentrated liquid stage, polishing rate, cleanability, etc., in some embodiments, the content W1 of the first water-soluble polymer is preferably 0.03 wt % or less, more preferably 0.015 wt % or less, and even more preferably 0.01 wt % or less. The polishing liquid disclosed herein may also be implemented in an embodiment in which the content W1 of the first water-soluble polymer is, for example, 0.008 wt % or less, 0.006 wt % or less, or 0.004 wt % or less.

[0108] Although not particularly limited, in some embodiments, the content W2 of the second water-soluble polymer in the polishing liquid may be, for example, 0.0001 wt % or more, typically 0.0005 wt % or more, from the viewpoint of reducing defects, etc., and is preferably 0.001 wt % or more, or may be 0.002 wt % or more, or may be 0.003 wt % or more, or may be 0.004 wt % or more. The upper limit of the content W2 of the second water-soluble polymer is not particularly limited, and may be, for example, 0.1 wt % or less. From the viewpoint of stability, polishing rate, cleanability, etc. at the concentrated liquid stage, in some embodiments, the content W2 of the second water-soluble polymer is preferably 0.05 wt % or less, more preferably 0.02 wt % or less, and even more preferably 0.01 wt % or less (e.g., less than 0.01 wt %), and may be 0.007 wt % or less, or may be 0.005 wt % or less.

[0109] The total content (total amount) of water-soluble polymers in the polishing liquid is not particularly limited, and in some embodiments, it can be, for example, 0.0001 wt% or more. From the viewpoint of improving surface quality, the total content is preferably 0.0005 wt% or more, more preferably 0.001 wt% or more, even more preferably 0.002 wt% or more, and may be, for example, 0.005 wt% or more. In some embodiments, the upper limit of the total content is, for example, 0.5 wt% or less, and from the viewpoint of polishing rate, it is preferably 0.2 wt% or less, more preferably 0.1 wt% or less, even more preferably 0.05 wt% or less, particularly preferably 0.02 wt% or less, and may be 0.01 wt% or less (e.g., less than 0.01 wt%).

[0110] 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. Usually, 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 reducing defects and haze, the content is preferably 0.0001 wt % or more, more preferably 0.0003 wt % or more, and even more preferably 0.0005 wt % or more. Furthermore, from the viewpoint of polishing rate, etc., in some embodiments, the content is preferably 0.1 wt % or less, more preferably 0.01 wt % or less, even more preferably 0.005 wt % or less, and particularly preferably 0.001 wt % or less (for example, less than 0.001 wt %).

[0111] <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.

[0112] 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).

[0113] 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.

[0114] In some embodiments, the total content (total amount) of water-soluble polymers in the concentrate can be, for example, 3 wt % or less. From the viewpoint of the filterability and washability of the polishing composition, the content is usually preferably 1 wt % or less, more preferably 0.5 wt % or less. Furthermore, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content is usually 0.001 wt % or more, preferably 0.005 wt % or more, more preferably 0.01 wt % or more, and even more preferably 0.1 wt % or more.

[0115] 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.

[0116] <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.

[0117] 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.

[0118] <Applications> The polishing composition disclosed herein is suitable for polishing a surface made of a silicon material (typically, polishing a silicon wafer). Specific examples of silicon materials include silicon single crystal, amorphous silicon, and polysilicon. The polishing composition disclosed herein can be particularly preferably used for polishing a surface made of silicon single crystal (for example, polishing a silicon wafer).

[0119] The polishing composition disclosed herein can be preferably applied to a polishing process of a substrate (e.g., a silicon wafer). Before the polishing process using the polishing composition disclosed herein, the substrate may be subjected to a general treatment that can be applied to a substrate in a process upstream of the polishing process, such as lapping or etching.

[0120] The polishing composition disclosed herein is effective when used in the final polishing step of a substrate (e.g., a silicon wafer) or in the polishing step immediately preceding it, and is particularly preferably used in the final polishing step. Here, the final 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 final polishing step (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 final polishing step.

[0121] 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.

[0122] <Polishing> The polishing composition disclosed herein can be used to polish a substrate, for example, in an embodiment including the following steps. A preferred embodiment of a method for polishing a silicon wafer as a substrate 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 the polishing liquid as is.

[0123] Next, the polishing liquid is supplied to the substrate, and polishing is performed 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 a polishing liquid is supplied to the surface to be polished of the silicon wafer through the polishing pad of the polishing device. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface to be polished of the silicon wafer, and the two are moved relatively (for example, rotated). Polishing of the substrate is completed through this polishing process.

[0124] 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.

[0125] Substrates polished with the polishing composition disclosed herein are typically cleaned. Cleaning can be performed using an appropriate cleaning solution. The cleaning solution used is not particularly limited, and for example, SC-1 cleaning solution (ammonium hydroxide (NH )) commonly used in the field of semiconductors, etc. 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.

[0126] As described above, the technology disclosed herein can include a method for manufacturing a polished product (e.g., a method for manufacturing a silicon wafer) that includes a polishing step (preferably finish polishing) by any of the polishing methods described above, and the provision of a polished product (e.g., a silicon wafer) manufactured by the method.

[0127] The present specification discloses the following: [1] A polishing composition used for polishing a surface made of a silicon material, comprising abrasive grains (A), a basic compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) having a chemical structure different from that of the first water-soluble polymer (C1), wherein the first water-soluble polymer (C1) is a random copolymer containing vinyl alcohol units and N-vinylpyrrolidone units. [2] The polishing composition according to [1] above, wherein the second water-soluble polymer (C2) is at least one selected from the group consisting of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers, polymers containing nitrogen atoms, and carboxylic acid-based polymers. [3] The polishing composition according to [1] or [2] above, wherein the ratio of the content of the second water-soluble polymer (C2) to the content of the first water-soluble polymer (C1) is 0.1 or more and 20 or less by weight. [4] The weight average molecular weight of the first water-soluble polymer (C1) is 2×10 ４The polishing composition according to any one of [1] to [3] above, which is the following: [5] The polishing composition according to any one of [1] to [4] above, which contains silica particles as the abrasive grains (A). [6] The polishing composition according to any one of [1] to [5] above, which further contains a surfactant (D). [7] A concentrated solution of the polishing composition according to any one of [1] to [6] above. [8] A polishing method, which comprises polishing a surface made of a silicon material with the polishing composition according to any one of [1] to [7] above.

[0128] 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.

[0129] <Preparation of Polishing Composition> (Example 1) A concentrated solution of the polishing composition according to this example was prepared by mixing abrasive grains, a basic compound, a water-soluble polymer, a surfactant, and deionized water. Colloidal silica with an average primary particle size of 25 nm was used as the abrasive grains. Ammonia was used as the basic compound. A water-soluble polymer having a vinyl alcohol unit and an N-vinylpyrrolidone unit and a Mw of about 3.0 × 10 ４ and a random copolymer (poly(VA-r-VP); first water-soluble polymer) of about 35 × 10 ４ and polyacryloylmorpholine (PACMO; second water-soluble polymer) of 0.01%. As a surfactant, polyoxyethylene decyl ether (C10EO5) having 5 moles of ethylene oxide added was used. The obtained concentrated solution of the polishing composition was diluted 40 times by volume with deionized water to obtain a polishing composition according to this example having an abrasive concentration of 0.13%, a basic compound concentration of 0.01%, a poly(VA-r-VP) concentration of 0.003%, a PACMO concentration of 0.004%, and a C10EO5 concentration of 0.001%.

[0130] Example 2: A second water-soluble polymer having a Mw of about 27×10 ４ The polishing composition of this example was prepared in the same manner as in Example 1 except for the above.

[0131] Example 3: First water-soluble polymer having Mw of about 1.4 × 10 ４ The polishing composition of this example was prepared in the same manner as in Example 1.

[0132] Example 4 A random copolymer (poly(VA-r-VP)) having a Mw of about 3,000 was used as the first water-soluble polymer. Otherwise, the polishing composition of this example was prepared in the same manner as in Example 1.

[0133] Comparative Example 1: A first water-soluble polymer having a Mw of about 1.0×10 ４ Acetalized polyvinyl alcohol (ac-PVA) of the above formula was used. The polishing composition of this example was prepared in the same manner as in Example 1 except for the above.

[0134] Comparative Example 2: A first water-soluble polymer having a vinyl alcohol unit and an N-vinylpyrrolidone unit and a Mw of about 17.5×10 ４ The polishing composition of this example was prepared in the same manner as in Example 1 except for the above.

[0135] Comparative Example 3 A polishing composition according to this example was prepared in the same manner as in Example 1 except that only poly(VA-r-VP) was used as the water-soluble polymer, and the second water-soluble polymer was not used.

[0136] <Polishing of Silicon Wafer> A commercially available silicon single crystal wafer (conductivity type: P-type, crystal orientation: <100>, COP (Crystal Originated Particle)-free) having a diameter of 300 mm that had been subjected to lapping and etching was pre-polished under the following polishing condition 1. The pre-polishing was carried out using a polishing solution containing 0.6% abrasive grains (colloidal silica having an average primary particle size of 35 nm) and 0.08% tetramethylammonium hydroxide (TMAH) in deionized water.

[0137] [Polishing condition 1] Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tool Works, model "PNX-332B" Polishing load: 20 kPa Rotation speed of surface plate: 20 rpm Rotation speed of head (carrier): 20 rpm Polishing pad: Product name "SUBA400" manufactured by Nitta DuPont Polishing liquid supply rate: 1.0 L / min Polishing liquid temperature: 20°C Surface plate cooling water temperature: 20°C Polishing time: 2 min

[0138] The polishing compositions according to the examples prepared above were used as polishing liquids to polish the silicon wafers after the pre-polishing described above under the following polishing conditions 2, and subsequently under the polishing conditions 3.

[0139] [Polishing condition 2] Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tool Works, model "PNX-332B" Polishing load: 16 kPa Rotation speed of surface plate: 52 rpm Rotation speed of head (carrier): 50 rpm Polishing pad: Product name "POLYPAS275NX" manufactured by Fujibo Ehime Co., Ltd. Supply rate of polishing liquid: 1.5 L / min Temperature of polishing liquid: 20°C Temperature of surface plate cooling water: 20°C Polishing time: 2 min

[0140] [Polishing condition 3] Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tool Works, model "PNX-332B" Polishing load: 20 kPa Rotation speed of surface plate: 52 rpm Rotation speed of head (carrier): 50 rpm Polishing pad: Product name "POLYPAS275NX" manufactured by Fujibo Ehime Co., Ltd. Supply rate of polishing liquid: 1.5 L / min Temperature of polishing liquid: 20°C Temperature of surface plate cooling water: 20°C Polishing time: 2 min

[0141] <Water-repellent distance measurement> When the polished silicon wafer was unloaded, the longest radial distance (water-repellent distance) of the water-repellent region from the wafer edge was measured. The measured value (mm) was converted to a relative value, with the measured value (mm) for Comparative Example 1 being set to 100%, and the obtained value is shown in the corresponding column in Table 1. The smaller the water-repellent distance (%), the better the wettability was evaluated.

[0142] <Cleaning> The polished silicon wafer was removed from the polishing apparatus and, using a single-wafer cleaning machine, washed with an ozone water cleaning solution (60 seconds), then washed with an SC-1 cleaning solution and a brush (110 seconds), and then washed with an ozone water cleaning solution (20 seconds) and a hydrofluoric acid cleaning solution (15 seconds) in one set, for a total of 15 sets of cleaning processes, and then further washed with an ozone water cleaning solution (20 seconds). Thereafter, the silicon wafer was dried.

[0143] <LPD Measurement> The number of LPDs present on the surfaces of the silicon wafers after cleaning was measured in Oblique mode using a wafer inspection device, product name "Surfscan SP5," manufactured by KLA-Tencor Corporation. The measured values ​​were converted into relative values, with the number of LPDs in Comparative Example 1 being set to 100%, and the obtained values ​​are shown in the corresponding columns in Table 1.

[0144]

[0145] As shown in Table 1, in polishing compositions containing abrasive grains, a basic compound, and two types of water-soluble polymers, Examples 1 to 4, which used a random copolymer containing VA units and VP units as the water-soluble polymer, showed significantly shorter water-repellent distances and reduced LPDs compared to Comparative Example 1, which did not use a random copolymer containing VA units and VP units as the water-soluble polymer. Comparative Example 2, which used a PVA-PVP graft copolymer as one of the two water-soluble polymers, was able to reduce LPD, but the water-repellent distance increased, confirming a tendency for poor wettability. Comparative Example 3, which used only poly(VA-r-VP) as the water-soluble polymer, showed a small water-repellent distance but was unable to reduce LPD.

[0146] 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 used for polishing a surface made of a silicon material, comprising: an abrasive grain (A); a basic compound (B); a first water-soluble polymer (C1); and a second water-soluble polymer (C2) having a chemical structure different from that of the first water-soluble polymer (C1), wherein the first water-soluble polymer (C1) is a random copolymer containing vinyl alcohol units and N-vinylpyrrolidone units.

2. The polishing composition described in claim 1, wherein the second water-soluble polymer (C2) is at least one selected from the group consisting of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol-based polymers, polymers containing nitrogen atoms, and carboxylic acid-based polymers.

3. A polishing composition as described in claim 1 or 2, wherein the ratio of the content of the second water-soluble polymer (C2) to the content of the first water-soluble polymer (C1) is 0.1 or more and 20 or less, on a weight basis.

4. The weight average molecular weight of the first water-soluble polymer (C1) is 2×10 ４ 3. The polishing composition according to claim 1, wherein:

5. The polishing composition according to claim 1 or 2, comprising silica particles as the abrasive grains (A).

6. The polishing composition according to claim 1 or 2, further comprising a surfactant (D).

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

8. 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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