Polishing composition and polishing method

Abstract

Provided is a polishing composition which is used for polishing a surface formed from a silicon material, has excellent wettability of the surface after polishing, and is capable of reducing defects. Provided is a polishing composition for polishing a surface formed from 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) 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 a vinyl alcohol unit and an N-vinylpyrrolidone unit.

Description

Technical Field

[0001] This invention relates to a grinding composition.

[0002] This application claims priority based on Japanese Patent Application No. 2023-161703, filed on September 25, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] For the surfaces of materials such as metals, semi-metals, non-metals, and their oxides, abrasive compositions are used for precision grinding. For example, the surface of silicon wafers, which are used as components of semiconductor devices, is typically processed into a high-quality mirror finish through lapping (coarse grinding) and polishing (fine grinding). The polishing process generally includes a pre-polishing step (preparatory grinding step) and a fine polishing step (final grinding step). Related technical literature on abrasive compositions mainly used in grinding semiconductor substrates such as silicon wafers includes Patent Documents 1-2.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6185432

[0007] Patent Document 2: Japanese Patent Application Publication No. 2020-161603 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] Polishing compositions used for polishing semiconductor substrates such as silicon wafers and other substrates, for example, those used in fine polishing steps (especially fine polishing steps for semiconductor substrates such as silicon wafers or other substrates), are required to achieve high-quality surface performance after polishing. For example, by including water-soluble polymers in the polishing composition to properly protect the substrate, the surface quality after polishing, such as the reduction in haze value, can be improved. For example, Patent Documents 1 and 2 describe a polishing composition containing colloidal silica, ammonia, polyacrylamide morpholine as a water-soluble polymer, and polyvinyl alcohol, and studies have been conducted on the reduction in haze value caused by this polishing composition. On the other hand, when the protection of the substrate by the aforementioned water-soluble polymer is insufficient, defects will appear on the surface after polishing, such as being detected as LPD (Light Point Defect). Furthermore, when the surface of the polished substrate contains residues of the aforementioned water-soluble polymers, these will be detected as dust during surface inspection of the substrate, which may also be a factor increasing LPD. For this reason, when using a polishing composition containing water-soluble polymers for polishing, it is necessary to evaluate whether the surface quality is high by confirming the degree of reduction in defects (e.g., LPD) on the surface of the polished substrate.

[0010] Furthermore, to obtain a high-quality surface, it is preferable that the surface of the polished silicon wafer has sufficient wettability. By keeping the polished surface moist (with a film of water adhering to it) with water, foreign matter and other contaminants can be prevented from directly adhering to the polished surface. Silicon wafers with such a surface are easier to clean and achieve a higher quality surface.

[0011] The present invention was made in view of the above circumstances, and its object is to provide a polishing composition for polishing a surface formed of silicon material, wherein the polished surface has excellent wettability and can reduce defects.

[0012] Solution for solving the problem

[0013] According to this specification, a polishing composition is provided for polishing surfaces formed of silicon material. The polishing composition comprises abrasive particles (A), an alkaline compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) having a different chemical structure from the first water-soluble polymer (C1). The first water-soluble polymer (C1) is a random copolymer comprising vinyl alcohol units and N-vinylpyrrolidone units. According to the polishing composition, the polished surface formed of silicon material exhibits excellent wettability, and defects on the surface can be reduced.

[0014] In various ways, the second water-soluble polymer (C2) is selected from at least one group consisting of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol polymers, nitrogen-containing polymers, and carboxylic acid polymers. By combining the second water-soluble polymer (C2) selected from the above categories with the first water-soluble polymer (C1), excellent wettability and reduced defects can be achieved.

[0015] In various methods, 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, based on weight. The effects of the present disclosure can preferably be achieved when using the first water-soluble polymer (C1) and the second water-soluble polymer (C2) in the above-mentioned proportions.

[0016] In various methods, the weight-average molecular weight of the first water-soluble polymer (C1) is 2 × 10⁻⁶. 4 The following is a preferred method for achieving excellent wettability and reducing defects by using a first water-soluble polymer (C1) having the aforementioned weight-average molecular weight.

[0017] In various ways, the grinding composition includes silica particles as the aforementioned abrasive grains (A). Based on the grinding composition containing silica particles as abrasive grains, it is easy to obtain a ground surface with excellent surface quality.

[0018] In several ways, the grinding composition further includes a surfactant (D). With this configuration, the surface quality after grinding tends to be further improved.

[0019] The grinding composition disclosed herein can be a concentrate. The grinding composition disclosed herein can be manufactured, distributed, and stored in the form of a concentrate.

[0020] Among various methods, a polishing method is provided, which includes the step of polishing a surface formed of silicon material using the above-described polishing composition. According to the above polishing method, the polished surface formed of silicon material exhibits excellent wettability and can reduce defects on the surface. Detailed Implementation

[0021] The following describes suitable embodiments of the present invention. It should be noted that matters necessary for implementing the present invention, other than those specifically mentioned in this specification, are understood to be design matters based on prior art by those skilled in the art. The present invention can be implemented based on the disclosures in this specification and common technical knowledge in this field.

[0022] <Abrasive grains (A)>

[0023] The grinding composition disclosed herein comprises abrasive grains. These abrasive grains contribute to increasing the grinding rate by mechanically grinding the surface of the object being ground. The material or properties of the abrasive grains are not particularly limited and can be appropriately selected based on the intended use or method of application of the grinding 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 hematite 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 to particles containing acrylic acid and methacrylic acid), and polyacrylonitrile particles. Such abrasive grains can be used alone or in combination of two or more.

[0024] As the aforementioned abrasive grains, inorganic particles are preferred, particularly those composed of oxides of metals or semi-metals, and especially silicon dioxide particles. The use of silicon dioxide particles as abrasive grains is particularly meaningful in abrasive compositions that can be used for polishing (e.g., fine polishing) objects such as silicon wafers having surfaces formed of silicon. The technology disclosed herein, for example, preferably employs essentially only silicon dioxide particles as the aforementioned abrasive grains. From this viewpoint, it is suitable for the proportion of silicon dioxide particles in the total amount of abrasive grains to be 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).

[0025] Specific examples of silica particles include colloidal silica, fumed silica, and precipitated silica. Silica particles can be used alone or in combination of two or more. From the viewpoint of easily obtaining a polished surface with excellent quality after grinding, colloidal silica is particularly preferred. As colloidal silica, examples preferably are colloidal silica produced by ion exchange using water glass (Na silicate) as a raw material, and alkoxide-based colloidal silica (colloidal silica produced through the hydrolysis and condensation reaction of alkoxysilanes). Colloidal silica can be used alone or in combination of two or more.

[0026] 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. There is no particular upper limit to the true specific gravity of the silica, but it is generally 2.3 or less, for example, 2.2 or less. The true specific gravity of the silica particles can be determined by a liquid substitution method using ethanol as the substitution liquid.

[0027] The average primary particle size of the abrasive grains (generally silica particles, preferably colloidal silica) is not particularly limited, but from the viewpoint of grinding rate, it is preferably 5 nm or more, more preferably 10 nm or more. From the viewpoint of obtaining higher grinding effects (e.g., reduction of haze, removal of defects, etc.), the above-mentioned average primary particle size is preferably 15 nm or more, more preferably 20 nm or more (e.g., more than 20 nm). Furthermore, from the viewpoint of preventing scratches, the average primary particle size 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 lower haze, the average primary particle size of the abrasive grains can be 43 nm or less, less than 40 nm, less than 38 nm, less than 35 nm, less than 32 nm, or less than 30 nm in various ways.

[0028] It should be noted that in this specification, the average primary particle size refers to the specific surface area (BET value) measured by the BET method, expressed as: average primary particle size (nm) = 6000 / (true density (g / cm³)). 3 )×BET value (m 2 The particle size (BET particle size) is calculated using the formula ( / g). The specific surface area can be measured, for example, using a surface area measuring device manufactured by Micromeritex, trade name "FlowSorb II 2300".

[0029] The average secondary particle size of the abrasive grains (generally silica particles) is not particularly limited, and can be appropriately selected from a range of approximately 15 nm to 300 nm. From the viewpoint of improving the grinding rate, the aforementioned average secondary particle size is preferably 30 nm or more. More preferably, it is 35 nm or more. In various embodiments, the aforementioned average secondary particle size can be, for example, 40 nm or more, or 42 nm or more, preferably 44 nm or more. Furthermore, the aforementioned average secondary particle size is generally advantageous to be below 250 nm, preferably below 200 nm, and more preferably below 150 nm. In various embodiments, the aforementioned average secondary particle size is 120 nm or less, more preferably below 100 nm, and even more preferably below 70 nm, for example, below 60 nm or below 50 nm.

[0030] It should be noted that, 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 abrasive grains can be measured, for example, by using the dynamic light scattering method of the product "NanotracUPA-UT151" manufactured by Nikkiso Corporation.

[0031] The shape (outer shape) of the abrasive particles (generally silica particles) can be spherical or non-spherical. Specific examples of non-spherical particles include: peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, konpeito-shaped, rugby ball-shaped, etc. For example, it is preferable to use silica particles that are mostly peanut-shaped or cocoon-shaped.

[0032] While not specifically limited, the average aspect ratio (average aspect ratio) of the abrasive grains (generally silica particles) is generally 1.0 or higher, preferably 1.05 or higher, more preferably 1.1 or higher, and can be 1.2 or higher. Increasing the average aspect ratio allows for higher grinding rates. Furthermore, from the viewpoint of reducing scratches, the average aspect ratio of the abrasive grains (generally silica particles) is preferably 3.0 or lower, more preferably 2.0 or lower, more preferably 1.5 or lower, and can be 1.4 or lower.

[0033] The shape (outline) or average aspect ratio of abrasive grains (typically silica particles) can be determined, for example, by observation using an electron microscope. A specific procedure for determining the average aspect ratio involves, for example, using a scanning electron microscope (SEM), drawing the smallest rectangle circumscribed to each individual grain image for a specific number (e.g., 200) of identifiable, individual grain shapes. Then, for each rectangle drawn for each grain image, the length of its longer side (the value of the major diameter) is divided by the length of its shorter side (the value of the minor diameter), and this value is used as the major diameter / minor diameter ratio (ARR). The average aspect ratio is obtained by arithmetically averaging the aspect ratios of the specific number of grains mentioned above.

[0034] <Basic Compound (B)>

[0035] The grinding composition disclosed herein contains an alkaline compound. In this specification, an alkaline compound refers to a compound that dissolves in water and has the function of increasing the pH of the aqueous solution. By including an alkaline compound in the grinding composition, the workpiece can be efficiently ground using its chemical grinding action (alkaline etching). As the alkaline compound, organic or inorganic alkaline compounds containing nitrogen, alkaline compounds containing phosphorus, alkali metal hydroxides, alkaline earth metal hydroxides, various carbonates or bicarbonates, etc., can be used. Examples of nitrogen-containing alkaline compounds include quaternary ammonium compounds, ammonia, amines (preferably water-soluble amines), etc. Examples of phosphorus-containing alkaline compounds include quaternary phosphorus compounds. Such alkaline compounds can be used alone or in combination of two or more.

[0036] 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, imidazoles, triazoles, and other azoles. Specific examples of quaternary phosphonium compounds include tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

[0037] As quaternary ammonium compounds, quaternary ammonium salts (generally strong bases) such as tetraalkylammonium salts and hydroxyalkyltrialkylammonium salts can be used. The anionic component of this quaternary ammonium salt can be, for example, OH-. - F - Cl - ,Br - I - ClO4 - BH4 - Examples of the aforementioned quaternary ammonium compounds include those with anions of OH-. - Quaternary ammonium salts, namely quaternary ammonium hydroxides. Specific examples of quaternary ammonium hydroxides include: tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide, etc.; hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide (called choline); etc.

[0038] In such basic compounds, for example, at least one basic compound selected from alkali metal hydroxides, quaternary ammonium hydroxides, and ammonia can be preferred. Among these, tetraalkylammonium hydroxide (e.g., tetramethylammonium hydroxide) and ammonia are more preferred, and ammonia is particularly preferred.

[0039] <Water-soluble polymer (C)>

[0040] The polishing composition disclosed herein comprises at least two water-soluble polymers. In other words, the polishing composition disclosed herein comprises 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) in combination, the advantages based on the different effects of each water-soluble polymer can be enjoyed. This results in excellent wettability of the polished surface and reduces defects on the surface.

[0041] <First Water-Soluble Polymer (C1)>

[0042] The first water-soluble polymer is a random copolymer comprising vinyl alcohol units (hereinafter also referred to as "VA units") and N-vinylpyrrolidone units (hereinafter also referred to as "VP units"). The VA unit refers to a structural unit (repeating unit) in one molecule of the random copolymer represented by the following chemical formula: -CH2-CH(OH)-. The VA unit can be obtained, for example, by hydrolyzing (also called saponifying) the structural unit of an ethylene ester monomer such as vinyl acetate through ethylene polymerization. The VP unit refers to a structural unit 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 partially or completely saponifying a random copolymer of vinyl acetate and N-vinylpyrrolidone. By using the first water-soluble polymer having the above chemical structure, the polished surface can be appropriately protected while exhibiting excellent wettability. The first water-soluble polymer can be used alone or in combination with two or more different molar ratios of VA and VP units, and two or more different Mw values.

[0043] There is no particular limitation on the molar ratio (VA / VP) of VA units to VP units in the first water-soluble polymer. The aforementioned molar ratio (VA / VP) can be set within an appropriate range to achieve the function of a random copolymer. In various ways, the aforementioned molar ratio (VA / VP) can 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., exceeding 90 / 10). Furthermore, in various ways, the aforementioned molar ratio (VA / VP) can be, for example, 99 / 1 or less, 98 / 2 or less, 97 / 3 or less, 95 / 5 or less, or 93 / 7 or less.

[0044] There is no particular limitation on the weight-average molecular weight (Mw) of the first water-soluble polymer. Sufficient wettability can be obtained in both low and high molecular weight cases, depending on the random copolymer containing VA and VP units. While there is no particular limitation, in various ways, the Mw of the first water-soluble polymer can be, for example, 100 × 10⁻⁶. 4 The following is 60×10 4 The following is suitable. Considering factors such as concentration efficiency, among various preferred methods, the above Mw is 30 × 10⁴. 4 For example, it could be 20×10 4 The following can be 10×10 4 The following can be 8×10 4 The following can be 5×10 4 The following can be 3×10 4The dispersion stability of the first water-soluble polymer tends to increase as Mw decreases. The preferred Mw is 2 × 10⁻⁶. 4 For example, it could be 1.8 × 10 4 The following can be 1.5 × 10 4 The following (e.g., less than 1.5 × 10) 4 By using a first water-soluble polymer with Mw within the aforementioned range, excellent wettability and reduced defects can preferably be achieved. Furthermore, from the viewpoint of appropriately protecting the polished surface while improving wettability after polishing, the aforementioned Mw can, for example, be 0.2 × 10⁻⁶. 4 The above can be 0.25×10 4 The above can be 0.3×10 4 The above can be 0.5×10 4 The above can be 0.8 × 10 4 The above is true. As the Mw of the first water-soluble polymer increases, the protective effect on the object being ground tends to strengthen. From this perspective, among various preferred methods, the aforementioned Mw is 1.0 × 10⁻⁶. 4 Above (e.g., more than 1.0 × 10) 4 ), can be 1.5×10 4 The above can be 1.8 × 10 4 The above can be 2.0×10 4 Above (e.g., exceeding 2.0 × 10) 4 ), can be 2.3×10 4 The above can be 2.5 × 10 4 The above can be 2.8 × 10 4 above.

[0045] The molecular weight (Mw) of the water-soluble polymer can be calculated using the value obtained from water-based gel chromatography (GPC) (water-based, converted to polyethylene oxide). The same applies to the Mw of the first water-soluble polymer described above and the second water-soluble polymer described later. The GPC measuring apparatus can be the "HLC-8320GPC" manufactured by TOSOH Corporation. The determination can be performed, for example, under the conditions described below. The same method is used for the examples described later.

[0046] [GPC Measurement Conditions]

[0047] Sample concentration: 0.1% by weight

[0048] Column: TSKgel GMPW XL

[0049] Detector: Differential refractometer

[0050] Eluent: 100mM sodium nitrate aqueous solution

[0051] Flow rate: 1 mL / min

[0052] Measurement temperature: 40℃

[0053] Sample injection volume: 200 μL

[0054] While there are no particular limitations, in various methods, the content of the first water-soluble polymer in the grinding composition, relative to 100 parts by weight of the abrasive particles (generally silica particles), can be, for example, 0.01 parts by weight or more. From the viewpoint of improving wettability, setting it to 0.1 parts by weight or more is suitable, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, 1.5 parts by weight or more, or 2 parts by weight or more. Relative to 100 parts by weight of the abrasive particles, the content of the first water-soluble polymer can be, for example, 50 parts by weight or less, or 30 parts by weight or less. From the viewpoint of the dispersion stability of the grinding composition, in various methods, the content of the first water-soluble polymer relative to 100 parts by weight of the abrasive particles is suitable, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and can be less than 3 parts by weight or 2.5 parts by weight or less. By appropriately setting the amount of the first water-soluble polymer used within the above range, the grinding surface can be properly protected while achieving a surface with excellent wettability after grinding.

[0055] <Second water-soluble polymer (C2)>

[0056] The grinding composition disclosed herein includes a second water-soluble polymer in addition to a first water-soluble polymer. The second water-soluble polymer has a different chemical structure from the first water-soluble polymer. Preferably, one or more water-soluble polymers selected from random copolymers containing VA and VP units are used as the second water-soluble polymer. By using the first and second water-soluble polymers in combination, the surface of the object being ground can be appropriately protected and defects can be reduced.

[0057] Examples of second water-soluble polymers include compounds containing hydroxyl, carboxyl, acyloxy, sulfonyl, amide, imide, quaternary ammonium, heterocyclic, and vinyl structures. Examples of second water-soluble polymers include cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol polymers, nitrogen-containing polymers, and carboxylic acid polymers. Second water-soluble polymers can be derived from natural sources or are synthetic polymers.

[0058] In various ways, polymers derived from natural sources are used as the second water-soluble polymer. Examples of polymers derived from natural sources include cellulose derivatives and starch derivatives.

[0059] In several preferred embodiments, a cellulose derivative is used as the second water-soluble polymer. This cellulose derivative is a polymer comprising 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, carboxymethyl cellulose, etc. HEC is preferred.

[0060] In various ways, starch derivatives are used as the second water-soluble polymer. Starch derivatives are polymers containing α-glucose units as the main repeating unit, and examples include: pregelatinized starch, pullulan, carboxymethyl starch, cyclodextrin, etc.

[0061] In several preferred embodiments, a synthetic polymer is used as the second water-soluble polymer. The surface quality improvement effect of this disclosure is preferably achieved when a synthetic polymer is used as the second water-soluble polymer.

[0062] In various ways, polymers containing oxyalkylene units are used as the second water-soluble polymer. Examples of polymers containing oxyalkylene units include: polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) with propylene oxide (PO) or butylene oxide (BO), and random copolymers of EO with PO or BO. Among these, block copolymers of EO and PO or random copolymers of EO and PO are preferred. Block copolymers of EO and PO can be diblock copolymers or triblock copolymers containing PEO blocks and polypropylene oxide (PPO) blocks. Examples of the above triblock copolymers include PEO-PPO-PEO type triblock copolymers and PPO-PEO-PPO type triblock copolymers. Generally, PEO-PPO-PEO type triblock copolymers are more preferred.

[0063] It should be noted that, unless otherwise stated, in this specification, the term "copolymer" refers to various copolymers including random copolymers, alternating copolymers, block copolymers, graft copolymers, etc.

[0064] In block copolymers or random copolymers of EO and PO, the molar ratio (EO / PO) of EO constituting the copolymer is preferably greater than 1 from the viewpoint of water solubility and cleaning properties, more preferably 2 or more, and even more preferably 3 or more (e.g., 5 or more).

[0065] In various ways, the second water-soluble polymer may comprise a polyvinyl alcohol (PVA)-based polymer. A PVA-based polymer used as the second water-soluble polymer refers to a polymer containing VA units as its repeating units, and excluding random copolymers containing both VA and VP units. A PVA-based polymer may contain only VA units as repeating units, or it may contain repeating units other than VA units (hereinafter also referred to as "non-VA units"). A PVA-based polymer may be a random copolymer containing both VA and non-VA units, a block copolymer, an alternating copolymer, or a graft copolymer. A PVA-based polymer may contain only one type of non-VA unit, or it may contain two or more types of non-VA units.

[0066] The aforementioned polyvinyl alcohol (PVA) polymers can be either unmodified PVA or modified PVA. Here, unmodified PVA refers to a PVA polymer produced by hydrolyzing (saponifying) polyvinyl acetate, and substantially free of repeating units other than the repeating units (-CH2-CH(OCOCH3)-) and VA units formed by vinyl polymerization of vinyl acetate. The degree of saponification of the aforementioned unmodified PVA can be, for example, 60% or more, and from the viewpoint of water solubility, it can be 70% or more, 80% or more, or 90% or more. In many cases, the degree of saponification of unmodified PVA can be 98% or more (complete saponification).

[0067] Polyvinyl alcohol polymers can be modified PVAs containing VA units and non-VA units, wherein the non-VA units have at least one structure selected from oxoalkylene, carboxyl, (di)carboxyl, (di)carboxylic acid ester, phenyl, naphthyl, sulfonyl, amino, hydroxyl, amide, imide, nitrile, ether, ester, and their salts. Furthermore, non-VA units that can be included in the modified PVA can be, for example, repeating units derived from N-vinyl monomers, N-(meth)acryloyl monomers, 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, repeating units derived from (di)acetone compounds, etc., but are not limited to these. An example of the aforementioned N-vinyl monomer is N-vinylpyrrolidone. An example of the aforementioned N-(meth)acryloyl monomer is N-(meth)acryloylmorpholine. The aforementioned alkyl vinyl ethers can be, for example, propyl vinyl ether, butyl vinyl ether, 2-ethylhexyl vinyl ether, or other vinyl ethers having an alkyl group having 1 to 10 carbon atoms. The aforementioned vinyl esters of monocarboxylic acids having 3 or more carbon atoms can be, for example, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl hexanoate, or other vinyl esters of monocarboxylic acids having 3 to 7 carbon atoms. Examples of the aforementioned (ii) acetone compounds include: diacetone (meth)acrylamide and acetylacetone.

[0068] Furthermore, in various ways, acetalized polyvinyl alcohol (PVA) polymers can be used as the polyvinyl alcohol polymer. Examples of acetalized PVA polymers include modified PVA in which a portion of the VA units in the PVA polymer has been acetalized. The modified PVA (acetalized PVA (ac-PVA)) in which a portion of the VA units in the aforementioned PVA polymer has been acetalized can be obtained by reacting a portion of the hydroxyl groups of the PVA polymer with an aldehyde or ketone compound. Typically, acetalized PVA polymers can be obtained by acetalizing a PVA polymer with an aldehyde compound. In various ways, the aldehyde compound has 1 to 7 carbon atoms, for example, 2 to 7.

[0069] Examples of the aforementioned aldehyde compounds include: formaldehyde; straight-chain or branched alkanes such as acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, tert-butyraldehyde, and hexanal; and alicyclic or aromatic aldehydes such as cyclohexaneformaldehyde and benzaldehyde. They can be used alone or in combination of two or more. In addition to formaldehyde, aldehyde compounds can be those in which one or more hydrogen atoms are substituted with halogens, etc. From the viewpoint of high water solubility and ease of acetalization reaction, straight-chain or branched alkanes are preferred, such as acetaldehyde, n-propionaldehyde, n-butyraldehyde, and n-pentanaldehyde.

[0070] In addition to the above, aldehyde compounds such as 2-ethylhexanal, nonanal, and decanal, which have 8 or more carbon atoms, can also be used as aldehyde compounds.

[0071] Acetalized polyvinyl alcohol polymers comprise a structural part, namely the VA unit, represented by the following chemical formula: -CH2-CH(OH)-, and an acetalized structural unit (hereinafter also referred to as the "VAC unit") represented by the following general formula (1).

[0072]

[0073] (In formula (1), R is a hydrogen atom, or a straight-chain or branched alkyl group, which may be substituted with a functional group.)

[0074] In various ways, R in formula (1) above is a hydrogen atom, or a straight-chain or branched alkyl group having 1 to 6 carbon atoms. R can be one of them, or a combination of two or more. From the viewpoint of improving haze reduction performance, R can be a straight-chain or branched alkyl chain having 1 to 6 carbon atoms.

[0075] From the perspective of improving haze reduction performance, the degree of acetalization of acetalized polyvinyl alcohol polymers can be set at 1 mol% or more, 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 perspective of improving hydrophilicity, the degree of acetalization of acetalized polyvinyl alcohol polymers can be set to less than 60 mol%, less than 50 mol%, less than 40 mol%, or less than 35 mol% (e.g., less than 33 mol%). It should be noted that, in this specification, "degree of acetalization" refers to the proportion of acetalized structural units (VAC units) in all repeating units constituting the acetalized polyvinyl alcohol polymer.

[0076] Furthermore, cationic modified polyvinyl alcohols (PVA) with cationic groups such as quaternary ammonium structures can also be used as polyvinyl alcohol-based polymers. Examples of such cationic modified PVAs include PVAs with cationic groups derived from monomers possessing cationic groups, such as diallyl dialkylammonium salts and N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salts. Additionally, as vinyl alcohol-based polymers, non-VA units can also have the chemical formula: -CH2-CH(CR 1 (OR 4 )-CR 2 (OR 5 )-R 3 )- represents the polymer of the structural part. Here R 1 ~R 3 Each can independently represent a hydrogen atom or an organic group, R 4 and R5 Each independently represents a hydrogen atom or R 6 -CO-(where R is the formula) 6 (Represents an alkyl group). For example, R in the above chemical formula. 1 ~R 3 When at least one of them is an organic group, the organic group can be a straight-chain or branched alkyl group having 1 or more but less than 8 carbon atoms. Furthermore, R in the above chemical formula... 6 It can be a straight-chain or branched alkyl group with 1 or more but less than 8 carbon atoms.

[0077] Among various approaches, a modified PVA with a 1,2-diol structure in its side chain can be used as the modified PVA described above. For example, a modified PVA containing the aforementioned R can be preferably used as the modified PVA. 1 ~R 5 The non-VA unit of PVA with hydrogen atoms is modified PVA (butene glycol-vinyl alcohol copolymer (BVOH)).

[0078] The proportion of VA units in the total number of repeating units constituting the polyvinyl alcohol polymer can be, for example, 5% or more, 10% or more, 20% or more, or 30% or more. While not particularly limited, in various embodiments, the proportion of VA units can 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). The repeating units constituting the polyvinyl alcohol polymer can be substantially 100% VA units. Here, "substantially 100%" means that the polyvinyl alcohol polymer does not actively contain non-VA units; typically, the proportion of non-VA units in the total number of repeating units is less than 2% (e.g., less than 1%), including cases where it is 0%. In other embodiments, the proportion of VA units in the total number of repeating units constituting the polyvinyl alcohol polymer can be, for example, less than 95%, less than 90%, less than 80%, or less than 70%.

[0079] The content of VA units in polyvinyl alcohol (PVA) polymers (by weight) can be, for example, 5% or more by weight, 10% or more by weight, 20% or more by weight, or 30% or more by weight. While not specifically limited, in various configurations, the content of VA units can be 50% or more by weight (e.g., more than 50% by weight), 70% or more by weight, or 80% or more by weight (e.g., 90% or more by weight, 95% or more by weight, or 98% or more by weight). The repeating units constituting the PVA polymer can be substantially 100% by weight of VA units. Here, "substantially 100% by weight" means that at least no non-VA units are actively contained as repeating units constituting the PVA polymer; typically, this means that the content of non-VA units in the PVA polymer is less than 2% by weight (e.g., less than 1% by weight). In other configurations, the content of VA units in the PVA polymer can be, for example, less than 95% by weight, less than 90% by weight, less than 80% by weight, or less than 70% by weight.

[0080] Polyvinyl alcohol (PVA) polymers can contain multiple polymer chains with varying VA unit contents within the same molecule. Here, a polymer chain refers to a segment (chain segment) that constitutes part of a polymer molecule. For example, a PVA polymer can contain polymer chain A, which has a VA unit content higher than 50% by weight, and polymer chain B, which has a VA unit content lower than 50% by weight (i.e., a non-VA unit content higher than 50% by weight).

[0081] Polymer chain A may contain only VA units as repeating units, or it may contain non-VA units in addition to VA units. The content of VA units in 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 many cases, the content of VA units in polymer chain A may be 95% by weight or more, or 98% by weight or more. The repeating units constituting polymer chain A may be substantially 100% by weight VA units.

[0082] Polymer chain B may contain only non-VA units as repeating units, or it 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 many cases, the content of non-VA units in polymer chain B may be 95% by weight or more, or 98% by weight or more. The repeating units constituting polymer chain B may be substantially 100% by weight non-VA units.

[0083] Examples of polyvinyl alcohol-based polymers containing polymer chain A and polymer chain B within the same molecule include block copolymers and graft copolymers containing these polymer chains. The graft copolymers can be graft copolymers with polymer chain B (side chain) grafted onto polymer chain A (main chain), or graft copolymers with polymer chain A (side chain) grafted onto polymer chain B (main chain). In various ways, polyvinyl alcohol-based polymers with polymer chain B grafted onto polymer chain A can be used.

[0084] Examples of polymer chain B include: polymer chains with repeating units derived from N-vinyl monomers as the main repeating units; polymer chains with repeating units derived from N-(meth)acryloyl monomers as the main repeating units; polymer chains with repeating units derived from ethylene esters of dicarboxylic acids such as fumaric acid, maleic acid, and maleic anhydride as the main repeating units; polymer chains with repeating units derived from aromatic vinyl monomers such as styrene and vinylnaphthalene as the main repeating units; and polymer chains with oxoalkylene units as the main repeating units. It should be noted that, unless otherwise specified, in this specification, a main repeating unit refers to a repeating unit comprising more than 50% by weight.

[0085] As a suitable example of polymer chain B, a polymer chain with N-vinyl monomers as the main repeating units can be cited, i.e., an N-vinyl polymer chain. The content of repeating units derived from N-vinyl monomers in an N-vinyl polymer chain can typically be more than 50% by weight, more than 70% by weight, more than 85% by weight, or more than 95% by weight. Polymer chain B can essentially consist entirely of repeating units derived from N-vinyl monomers.

[0086] In this specification, examples of N-vinyl monomers include monomers having nitrogen-containing heterocycles (e.g., lactam rings) and N-vinyl chain amides. Specific examples of N-vinyl lactam monomers include: N-vinylpyrrolidone, N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. Specific examples of N-vinyl chain amides include: N-vinylacetamide, N-vinylpropionamide, N-vinylbutyric acid amide, etc. Polymer chain B, for example, may have more than 50% by weight (e.g., more than 70% by weight, or more than 85% by weight, or more than 95% by weight) of its repeating units being N-vinylpyrrolidone units in an N-vinyl polymer chain. The repeating units constituting polymer chain B may be substantially all N-vinylpyrrolidone units.

[0087] Other examples of polymer chain B include polymer chains with repeating units derived from N-(meth)acryloyl monomers as the main repeating units, i.e., N-(meth)acryloyl polymer chains. The content of repeating units derived from N-(meth)acryloyl monomers in N-(meth)acryloyl polymer chains typically exceeds 50% by weight, and can be 70% or more, 85% or more, or 95% or more. Polymer chain B can be substantially entirely composed of repeating units derived from N-(meth)acryloyl monomers.

[0088] In this specification, examples of N-(meth)acryloyl type monomers include: chain amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of chain amides having an N-(meth)acryloyl group include: (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, and N-n-butyl(meth)acrylamide; and N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, and N,N-di(n-butyl)(meth)acrylamide. Examples of cyclic amides having an N-(meth)acryloyl group include N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine.

[0089] Other examples of polymer chain B include polymer chains containing oxoalkylene units as the main repeating units, i.e., oxoalkylene polymer chains. The content of oxoalkylene units in oxoalkylene polymer chains typically exceeds 50% by weight, but can be 70% or more by weight, 85% or more by weight, or 95% or more by weight. In fact, virtually all repeating units in polymer chain B can be oxoalkylene units.

[0090] Examples of oxoalkylene units include oxoethylene units, oxopropylene units, and oxobutylene units. These oxoalkylene units can be repeating units derived from the corresponding alkylene oxides. The oxoalkylene units contained in an oxoalkylene polymer chain can be one type or more types. For example, it can be an oxoalkylene polymer chain containing a combination of oxoethylene and oxopropylene units. In oxoalkylene polymer chains containing two or more types of oxoalkylene units, these oxoalkylene units can be random copolymers of the corresponding alkylene oxides, block copolymers, alternating copolymers, or graft copolymers.

[0091] Further examples of polymer chain B include: polymer chains containing repeating units derived from alkyl vinyl ethers (e.g., vinyl ethers with alkyl groups having 1 or more and 10 or fewer carbon atoms), polymer chains containing repeating units derived from monocarboxylic acid vinyl esters (e.g., monocarboxylic acid vinyl esters having 3 or more carbon atoms), and polymer chains incorporating cationic groups (e.g., cationic groups having quaternary ammonium structures).

[0092] In various ways, the polyvinyl alcohol-based polymer as the second water-soluble polymer can be a copolymer containing VA units and non-VA units, i.e., modified polyvinyl alcohol. Furthermore, the degree of saponification of the modified polyvinyl alcohol-based polymer as the second water-soluble polymer is typically 50 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, for example, 75 mol% or more.

[0093] In many other ways, polyvinyl alcohol-based polymers may not be used as the second water-soluble polymer. The technology disclosed herein can preferably be implemented in a manner that substantially does not contain polyvinyl alcohol-based polymers as the second water-soluble polymer. For example, the proportion of polyvinyl alcohol-based polymers in the total second water-soluble polymer may be less than 50% by weight (e.g., less than 50% by weight), less than 30% by weight, less than 20% by weight, less than 10% by weight, or less than 5% by weight (e.g., 0 to 5% by weight).

[0094] In several preferred embodiments, a nitrogen-containing polymer is used as the second water-soluble polymer. High-quality abrasive surfaces can be easily obtained from a grinding composition comprising a nitrogen-containing polymer. The nitrogen-containing polymer is generally a polymer comprising repeating units derived from monomers having nitrogen atoms (repeating units containing nitrogen atoms). Non-limiting examples of nitrogen-containing polymers include: polymers comprising N-vinyl monomer units; polymers comprising N-(meth)acryloyl monomer units, etc. A single nitrogen-containing polymer can be used, or two or more can be used in combination.

[0095] In several preferred embodiments, an N-vinyl type polymer may be used as the second water-soluble polymer. Examples of N-vinyl type polymers include polymers containing repeating units derived from monomers having nitrogen-containing heterocycles (e.g., lactam rings). Examples of such polymers include homopolymers and copolymers of N-vinyl lactam type monomers (e.g., copolymers with a copolymerization ratio of N-vinyl lactam type monomers exceeding 50% by weight), homopolymers and copolymers of N-vinyl chain amides (e.g., copolymers with a copolymerization ratio of N-vinyl chain amides exceeding 50% by weight), etc.

[0096] Specific examples of N-vinyllactam monomers (i.e., compounds having a lactam structure and N-vinyl groups within a single molecule) include: N-vinylpyrrolidone (VP), N-vinylpiperidone, N-vinylmorpholinone, N-vinylcaprolactam (VC), N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. Specific examples of polymers containing N-vinyllactam 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 containing polymer chains containing one or both of VP and VC, alternating copolymers, graft copolymers, etc.

[0097] Specific examples of N-vinyl chain amides include: N-vinylacetamide, N-vinylpropionamide, N-vinylbutyric acid amide, etc.

[0098] In several preferred embodiments, an N-vinyl chain amide polymer is used as the second water-soluble polymer. Here, an N-vinyl chain amide polymer refers to a homopolymer or copolymer of N-vinyl chain amides (e.g., a copolymer in which the copolymerization ratio of N-vinyl chain amides exceeds 50% by weight). By using an N-vinyl chain amide polymer as the second water-soluble polymer, superior defect reduction effects can be easily obtained. The content of repeating units derived from N-vinyl chain amides in the N-vinyl chain amide polymer is generally greater than 50% by weight, but can be 70% by weight or more, 85% by weight or more, or 95% by weight or more. The N-vinyl chain amide polymer can be substantially entirely composed of repeating units derived from N-vinyl chain amides. A typical example of an N-vinyl chain amide polymer is poly-N-vinylacetamide (PNVA).

[0099] In several preferred embodiments, an N-(meth)acryloyl polymer can be used as the second water-soluble polymer. Examples of N-(meth)acryloyl polymers include homopolymers and copolymers containing 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 chain amides having N-(meth)acryloyl groups and cyclic amides having N-(meth)acryloyl groups. Based on N-(meth)acryloyl polymers (e.g., containing cyclic amides having N-(meth)acryloyl groups as monomer units), the effects of containing the first water-soluble polymer (improved wettability) can be more effectively utilized while protecting the substrate surface. It should be noted that in this specification, (meth)acryloyl type means including both acryloyl and methacryloyl types. Furthermore, in this specification, (meth)acryloyl means including both acryloyl and methacryloyl groups.

[0100] 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 comprising chain amides having N-(meth)acrylamide groups as monomer units include: homopolymers of N-isopropylacrylamide and copolymers of N-isopropylacrylamide (e.g., copolymers in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by weight). It should be noted that, in this specification, (meth)acrylamide means the presence of both acrylamide and methacrylamide.

[0101] Examples of cyclic amides having an N-(meth)acryloyl group include: N-acryloylmorpholine, N-acryloylthiomorpholine, N-acryloylpiperidine, N-acryloylpyrrolidine, N-methacryloylmorpholine, N-methacryloylpiperidine, N-methacryloylpyrrolidine, etc. Examples of polymers containing cyclic amides having an N-(meth)acryloyl group as monomer units include: acryloylmorpholine polymers (PACMO). Typical examples of acryloylmorpholine polymers include: homopolymers of N-acryloylmorpholine (ACMO) and copolymers of ACMO (e.g., copolymers with a copolymerization ratio of ACMO exceeding 50% by weight). In acryloylmorpholine polymers, the proportion of ACMO units in the total number of repeating units is typically 50% or more, and 80% or more (e.g., 90% or more, typically 95% or more) is suitable. The second water-soluble polymer can be composed entirely of repeating units, essentially consisting of ACMO units.

[0102] In various ways, carboxylic acid polymers can be 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 their salts, styrene-maleic anhydride copolymers, styrene sulfonic acid-maleic acid copolymers or their salts, 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 its salts, styrene-acrylic acid copolymers or their salts, styrene sulfonic acid-acrylic acid copolymers or their salts, copolymers of styrene sulfonate and acrylic acid, acrylic acid-vinyl acetate copolymers, and acrylic acid / sulfonic acid monomer copolymers. It should be noted that in this specification, (meth)acrylic acid means polymers containing both acrylic acid and methacrylic acid.

[0103] In various ways, a random copolymer containing VA units and VP units can be used as the second water-soluble polymer. In this case, a random copolymer with a chemical structure different from that of the first water-soluble polymer is used as the second water-soluble polymer. For example, a copolymer with a different molar ratio of VA units to VP units than that of the first water-soluble polymer can be used, or a copolymer with a different Mw than that of the first water-soluble polymer can be used.

[0104] While not particularly limited, the technology disclosed herein can preferably be implemented using one or more selected from cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and carboxylic acid polymers as the second water-soluble polymer. The second water-soluble polymer is preferably selected from cellulose derivatives, polymers containing oxyalkylene units, and polymers containing nitrogen atoms, more preferably selected from cellulose derivatives and polymers containing nitrogen atoms. For example, when using one or more selected from cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and carboxylic acid polymers (e.g., polymers containing nitrogen atoms) as the second water-soluble polymer, the proportion of one or more selected from cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polymers containing nitrogen atoms, and carboxylic acid polymers (e.g., polymers containing nitrogen atoms) in the total second water-soluble polymer can 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., 95-100% by weight).

[0105] There is no particular limitation on the Mw of the second water-soluble polymer. From the viewpoint of concentration efficiency, among various approaches, the Mw of the second water-soluble polymer can be, for example, approximately 200 × 10⁻⁶. 4 The following can be approximately 100×10 4 The following can be 70×10 4 The following can be 60×10 4 The following can be 50×10 4 The following can be 40×10 4 The following can be 30×10 4 The following. Furthermore, from the viewpoint of improving surface quality, in various ways, the aforementioned Mw can be, for example, 0.5 × 10⁻⁶. 4 The above can be 1×10 4 The above can be 5×10 4 The above can be 8×10 4 Above (e.g., more than 8×10) 4 In several preferred embodiments, the aforementioned Mw is suitably 10 × 10. 4 The above can be 15×10 4 The above can be 20×10 4 The above can be 25×10 4 The above can be 30×10 4 Above (e.g., more than 30×10) 4 High surface quality is readily obtained by using a second water-soluble polymer with high Mw.

[0106] While not particularly limited, the present disclosure is preferably implemented in a combination of a first water-soluble polymer having a relatively small Mw and a second water-soluble polymer having a relatively large Mw. In various preferred embodiments, the ratio (Mw1 / Mw2) of the Mw of the first water-soluble polymer to the Mw of the second water-soluble polymer is less than 1, and can 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 appropriately protecting the polished surface while further improving the wettability after polishing, the above ratio (Mw1 / Mw2) is preferably 0.08 or less, and can be 0.05 or less (e.g., less than 0.05 or 0.04 or less). Furthermore, in various methods, the aforementioned ratio (Mw1 / Mw2) can be greater than 0.001, greater than 0.005, greater than 0.008, greater than 0.01, greater than 0.05, or greater than 0.07.

[0107] While not particularly limited, in various embodiments, the content of the second water-soluble polymer in the grinding composition, relative to 100 parts by weight of the abrasive grains (generally silica particles), may be, for example, 0.01 parts by weight or more. From the viewpoint of reducing defects, 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, further preferably 2 parts by weight or more, and can be 2.5 parts by weight or more, or 3 parts by weight or more. Furthermore, the content of the second water-soluble polymer relative to 100 parts by weight of the abrasive grains may, for example, be 50 parts by weight or less, or 30 parts by weight or less. From the viewpoint of the dispersion stability of the grinding composition, in various embodiments, the content of the second water-soluble polymer relative to 100 parts by weight of the abrasive grains may 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 3.5 parts by weight or less. High surface quality can be obtained by appropriately setting the amount of the second water-soluble polymer within the above range.

[0108] While not particularly limited, in various embodiments, the ratio (B / C) of the content of the alkaline compound (B) to the total content (total: C) of the water-soluble polymers in the grinding composition, based on weight, can be set to, for example, 0.01 or more. From the viewpoint of grinding rate, setting it to 0.1 or more is appropriate, preferably 0.2 or more, more preferably 0.5 or more, and can be 0.7 or more. Furthermore, in various embodiments, the above-mentioned ratio (B / C), based on weight, can be, for example, 15 or less, and can be 10 or less. Moreover, from the viewpoint of properly protecting the grinding surface and maintaining or improving surface quality, the above-mentioned ratio (B / C) is appropriate to be 7 or less, preferably 5 or less, more preferably 2 or less, and can be, for example, 1.5 or less. By appropriately setting the total content of the water-soluble polymers and the alkaline compound to within the above-mentioned range of the ratio (B / C), high surface quality can be obtained.

[0109] While not particularly limited, in various embodiments, the total content (total amount) of water-soluble polymers contained in the abrasive composition, relative to 100 parts by weight of abrasive grains (generally silica particles), may be, for example, 0.01 parts by weight or more. 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, further preferably 2 parts by weight or more, particularly preferably 3 parts by weight or more, and may be 4 parts by weight or more, or may be 5 parts by weight or more. Furthermore, the total content of the aforementioned 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 abrasive composition, in various embodiments, the total content of the aforementioned 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, and may be 10 parts by weight or less (e.g., less than 10 parts by weight).

[0110] While not particularly limited, in various 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, by weight, is preferably 0.01 or more, or 0.1 or more, preferably 0.2 or more, and can be 0.4 or more, 0.6 or more, or 0.8 or more. In various preferred embodiments, the ratio (W2 / W1) can be 1.0 or more, 1.2 or more, or 1.4 or more. Furthermore, in various embodiments, the upper limit of the ratio (W2 / W1), by weight, is preferably 30 or less, or 20 or less, or can be 10 or less, 9 or less, 8 or less, 7 or less, or 6 or less. In various preferred embodiments, the ratio (W2 / W1) is preferably 5 or less, preferably 3 or less, and can 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 preferably achieved.

[0111] <Surfactant (D)>

[0112] In various ways, the grinding composition preferably includes a surfactant. By including a surfactant in the grinding composition, defects and haze on the grinding surface can be reduced. According to the technology disclosed herein, the quality of the grinding surface can be further improved by including the above-mentioned combination of water-soluble polymers and a surfactant. As a surfactant, any of anionic, cationic, nonionic, or amphoteric surfactants can be used. Generally, anionic or nonionic surfactants are suitable. From the viewpoint of low foaming properties or ease of pH adjustment, nonionic surfactants are more preferred. By using nonionic surfactants, there is a tendency to further improve the performance in reducing defects and haze. Examples include: alkylene oxide polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene oxide derivatives (e.g., polyoxyalkylene adducts) such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glycerol ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters; and nonionic surfactants such as copolymers of various alkylene oxides (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). Surfactants can be used alone or in combination of two or more.

[0113] Specific examples of nonionic surfactants include: block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO-PPO-PEO triblock copolymers, PPO-PEO-PPO 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 isodecanyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, and polyoxyethylene oil. Polyoxyethylene phenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene dehydrated sorbitol monolaurate, polyoxyethylene dehydrated sorbitol monopalmitate, polyoxyethylene dehydrated sorbitol monostearate, polyoxyethylene dehydrated sorbitol monostearate, polyoxyethylene dehydrated sorbitol monooleate, polyoxyethylene dehydrated sorbitol trioleate, polyoxyethylene sorbitol tetraoleic acid, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, etc. Preferred surfactants include: block copolymers of EO and PO (especially PEO-PPO-PEO type triblock copolymers), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (e.g., polyoxyethylene decyl ether). As a polyoxyethylene alkyl ether, a polyoxyethylene alkyl ether with an EO addition molar number of approximately 1 to 10 (e.g., approximately 3 to 8) is preferably used.

[0114] 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 grinding composition with excellent defect reduction properties can be easily obtained. Among various 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 can be 1000 or less (e.g., 500 or less). Furthermore, from the viewpoint of interfacial activity, a molecular weight of 200 or more is generally appropriate, and from the viewpoint of haze reduction effect, 250 or more (e.g., 300 or more) is preferred.

[0115] The preferred range of molecular weight of the surfactant can vary depending on the type of surfactant. For example, when using polyoxyethylene alkyl ether as a surfactant, its molecular weight is preferably less than 2000, more preferably less than 1900 (e.g., less than 1800), even more preferably less than 1500, and can be less than 1000 (e.g., less than 500). Furthermore, when using block copolymers of EO and PO as surfactants, for example, its weight-average molecular weight can be more than 500, more than 1000, more than 1500, more than 2000, and even more than 2500. The upper limit of the above-mentioned weight-average molecular weight is, for example, less than 5000, preferably less than 4500, and can be, for example, less than 4000, and less than 3500.

[0116] The molecular weight of a surfactant can be calculated from its chemical formula or obtained by GPC (converted from aqueous or polyethylene glycol). For example, in the case of polyoxyethylene alkyl ethers, the molecular weight calculated from the chemical formula is preferred, while in the case of block copolymers of EO and PO, the weight-average molecular weight obtained by GPC is preferred.

[0117] While not particularly limited, in the case of a grinding composition containing a surfactant, from the viewpoint of detergency, it is generally appropriate for the surfactant content to be 20 parts by weight or less relative to 100 parts by weight of the abrasive particles (generally silica particles), preferably 10 parts by weight or less, more preferably 5 parts by weight or less, further preferably 3 parts by weight or less, particularly preferably 1 part by weight or less (e.g., less than 1 part by weight), and can be 0.8 parts by weight or less. From the viewpoint of better utilizing the surfactant's effect, it is appropriate for the surfactant content to be 0.001 parts by weight or more relative to 100 parts by weight of the abrasive particles, preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and can be 0.3 parts by weight or more.

[0118] While not particularly limited, in the case where the grinding composition contains a surfactant, the ratio (D / C) of the surfactant content (D) to the total content (C) of the water-soluble polymer, based on weight, can be, for example, 0.001 or more. From the viewpoint of reducing defects, it is appropriate to be 0.005 or more, preferably 0.01 or more, more preferably 0.03 or more, and can be 0.05 or more. Furthermore, in various cases, the above ratio (D / C), based on weight, can be, for example, 10 or less. From the viewpoint of reducing defects, it is appropriate to be 1 or less (e.g., less than 1), preferably 0.5 or less, more preferably 0.3 or less, and can be, for example, 0.15 or less, and can be 0.10 or less.

[0119] <Water>

[0120] The water contained in the grinding composition of this disclosure is suitable for use as ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. To minimize the obstruction of the function of other components contained in the grinding composition, the water used preferably has a total transition metal ion content of less than 100 ppb. The purity of the water can be improved by, for example, removing impurity ions using ion exchange resins, removing foreign matter using filters, distillation, etc. It should be noted that the grinding composition of this disclosure may further contain an organic solvent (lower alcohols, lower ketones, etc.) that is homogeneous with water, as needed. The solvent contained in the grinding composition is preferably 90% by volume or more water, more preferably 95% by volume or more (e.g., 99-100% by volume) water.

[0121] <Other Ingredients>

[0122] The polishing composition disclosed herein may, as needed, further contain known additives such as organic acids, organic acid salts, inorganic acids, inorganic acid salts, chelating agents, preservatives, and fungicides that can be used in polishing compositions (e.g., polishing compositions for the fine polishing step of silicon wafers), without significantly impairing the effects of the present invention.

[0123] Organic acids and their salts, as well as 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 diphosphonic acid (HEDP) and methanesulfonic acid; organic phosphonic acids such as nitric acid tris(methylene phosphate) (NTMP) and phosphonobutane tricarboxylic acid (PBTC). Examples of organic acid salts include: alkali metal salts (sodium, potassium, lithium, etc.) or ammonium salts of organic acids. Examples of inorganic acids include: hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, hypophosphonic acid, boric acid, and carbonic acid. Examples of inorganic acid salts include: alkali metal salts (sodium, potassium, lithium, etc.) and ammonium salts of inorganic acids.

[0124] The aforementioned chelating agents can be used alone or in combination of two or more. Examples of such chelating agents include aminocarboxylic acid chelating agents and organophosphonic acid chelating agents. Suitable examples of chelating agents include ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and diethylenetriaminepentaacetic acid. Examples of such preservatives and fungicides include isothiazolinone compounds, parabens, phenoxyethanol, etc.

[0125] The polishing composition disclosed herein is preferably substantially free of oxidants. When the polishing composition contains oxidants, the surface of the substrate (e.g., a silicon wafer) will be oxidized and an oxide film will form because the polishing composition is supplied to it, which may reduce the polishing rate. Specific examples of oxidants mentioned herein include hydrogen peroxide (H2O2), sodium persulfate, ammonium persulfate, sodium dichloroisocyanurate, etc. It should be noted that "substantially free of oxidants" in polishing compositions means that they do not actively contain oxidants. Therefore, polishing compositions that unavoidably contain trace amounts of oxidants from raw materials or manufacturing processes (e.g., the molar concentration of the oxidant 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, further preferably 0.00005 mol / L or less, and particularly preferably 0.00001 mol / L or less) can be included within the concept of substantially oxidant-free polishing compositions as described herein.

[0126] <ph>

[0127] The pH of the polishing composition disclosed herein is not particularly limited, and an appropriate pH can be adopted depending on the substrate, etc. Among various methods, a pH of 8.0 or higher for the polishing composition is suitable, preferably 8.5 or higher, and more preferably 9.0 or higher. When the pH of the polishing composition increases, there is a tendency for the polishing rate to increase. On the other hand, from the viewpoint of preventing the dissolution of silica particles and suppressing the reduction of mechanical polishing effect, a pH of 12.0 or lower for the polishing composition is generally suitable, preferably 11.0 or lower, more preferably 10.8 or lower, and even more preferably 10.5 or lower.

[0128] It should be noted that, in the technology disclosed herein, the pH of the grinding composition can be measured using a pH meter (e.g., a glass electrode hydrogen ion concentration indicator (model F-72) manufactured by Horiba Corporation). More specifically, the following method is used: after calibration at three points using standard buffer solutions (phthalate pH buffer pH: 4.01 (25°C), neutral phosphate pH buffer pH: 6.86 (25°C), and carbonate pH buffer pH: 10.01 (25°C)), the glass electrode is inserted into the grinding composition to be tested for at least 2 minutes. After the pH of the grinding composition stabilizes, the pH of the grinding composition is measured.

[0129] <Grinding Fluid>

[0130] The polishing composition disclosed herein is typically supplied to the surface of a substrate in the form of an polishing slurry containing the polishing composition, and used for polishing the substrate. The polishing slurry can be, for example, a polishing slurry prepared by diluting any of the polishing compositions disclosed herein (typically by dilution with water). The polishing composition can also be used directly as a polishing slurry. Other examples of polishing slurries containing the polishing compositions disclosed herein include polishing slurries prepared by adjusting the pH of the composition.

[0131] The content of abrasive particles (generally silica particles) in the polishing slurry is not particularly limited, but is, for example, 0.005% by weight or more, preferably 0.01% by weight or more, more preferably 0.03% by weight or more, even more preferably 0.05% by weight or more, and can be 0.08% by weight or more, or 0.10% by weight or more (e.g., more than 0.10% by weight). Higher polishing rates can be achieved by increasing the abrasive particle content. A content of 10% by weight or less is suitable, preferably 7% by weight or less, more preferably 5% by weight or less, even more preferably 2% by weight or less, for example, 1% by weight or less, 0.5% by weight or less, 0.4% by weight or less, or 0.3% by weight or less. This facilitates the maintenance of surface quality.

[0132] The content of alkaline compounds in the polishing slurry is not particularly limited. From the viewpoint of increasing polishing rate, it is generally appropriate to set the above content at 0.0005% by weight or more, preferably 0.001% by weight or more, more preferably 0.003% by weight or more, and even more preferably 0.005% by weight or more (e.g., more than 0.005% by weight). Furthermore, from the viewpoint of improving surface quality (e.g., reducing haze), it is appropriate to set the above content at less than 0.1% by weight, preferably less than 0.05% by weight, more preferably less than 0.03% by weight (e.g., less than 0.025% by weight, and even more preferably less than 0.01% by weight).

[0133] While not particularly limited, in various methods, the content W1 of the first water-soluble polymer (specifically, a random copolymer containing VA and VP units) in the grinding slurry, from the viewpoint of improving wettability, can be, for example, 0.0001% by weight or more, typically 0.0005% by weight or more, preferably 0.001% by weight or more, for example 0.002% by weight or more, or 0.0025% by weight or more. The upper limit of the content W1 of the first water-soluble polymer is not particularly limited, for example, it can be set to 0.05% by weight or less. From the viewpoint of stability in the concentrate stage, or grinding rate, and cleaning properties, in various methods, the content W1 of the first water-soluble polymer is preferably 0.03% by weight or less, more preferably 0.015% by weight or less, and even more preferably 0.01% by weight or less. The grinding fluid disclosed herein can also be implemented in a manner where, for example, the content W1 of the first water-soluble polymer is 0.008% by weight or less, 0.006% by weight or less, or 0.004% by weight or less.

[0134] While not particularly limited, in various methods, the content W2 of the second water-soluble polymer in the grinding slurry, from the viewpoint of reducing defects, can be, for example, 0.0001% by weight or more, typically 0.0005% by weight or more, preferably 0.001% by weight or more, and can be 0.002% by weight or more, 0.003% by weight or more, or 0.004% by weight or more. The upper limit of the content W2 of the second water-soluble polymer is not particularly limited, and can be, for example, 0.1% by weight or less. From the viewpoint of stability in the concentrate stage, or grinding rate, and cleaning properties, in various methods, the content W2 of the second water-soluble polymer is preferably 0.05% by weight or less, more preferably 0.02% by weight or less, even more preferably 0.01% by weight or less (e.g., less than 0.01% by weight), can be 0.007% by weight or less, or can be 0.005% by weight or less.

[0135] The total content (total amount) of water-soluble polymers in the polishing slurry is not particularly limited, and in various ways, it can be set to, for example, 0.0001% by weight or more. From the viewpoint of improving surface quality, the above-mentioned total content is preferably 0.0005% by weight or more, more preferably 0.001% by weight or more, and even more preferably 0.002% by weight or more, for example, 0.005% by weight or more. Furthermore, in various ways, the upper limit of the above-mentioned total content is, for example, 0.5% by weight or less. From the viewpoint of polishing rate, it is preferably 0.2% by weight or less, more preferably 0.1% by weight or less, even more preferably 0.05% by weight or less, particularly preferably 0.02% by weight or less, and can be 0.01% by weight or less (for example, less than 0.01% by weight).

[0136] When surfactants are included, the content of surfactants in the polishing slurry (or the total content if two or more surfactants are included) is not particularly limited. Generally, from the viewpoint of detergency, the content of the aforementioned surfactants can be set to, for example, 0.00001% by weight or more. From the viewpoint of reducing defects and haze, a content of 0.0001% by weight or more is preferred, more preferably 0.0003% by weight or more, and even more preferably 0.0005% by weight or more is preferred. Furthermore, from the viewpoint of polishing rate, among various methods, it is preferable to set the aforementioned content to 0.1% by weight or less, more preferably 0.01% by weight or less, even more preferably 0.005% by weight or less, and particularly preferably 0.001% by weight or less (e.g., less than 0.001% by weight).

[0137] <Concentrated Solution>

[0138] The polishing composition disclosed herein can be in a concentrated form (i.e., a concentrated polishing slurry) before being supplied to a substrate. This concentrated polishing composition is advantageous from the perspectives of ease of manufacturing, distribution, storage, and cost reduction. The concentration ratio is not particularly limited; for example, it can be set at approximately 2 to 100 times the volume, and typically 5 to 50 times (e.g., 10 to 40 times) is suitable. Such a concentrated slurry can be diluted at a desired time to prepare a polishing slurry (working slurry), which is then supplied to the substrate. This dilution can be performed, for example, by adding water to the concentrated slurry and mixing.

[0139] When the grinding composition (i.e., concentrate) is diluted and used for grinding, the content of abrasive particles in the concentrate can be, for example, set to 25% by weight or less. From the viewpoint of dispersion stability or filterability of the grinding composition, this content is generally preferably 20% by weight or less, more preferably 15% by weight or less. In various preferred embodiments, the content of abrasive particles can be set to 10% by weight or less, or even 5% by weight or less. Furthermore, from the viewpoint of convenience in manufacturing, distribution, and storage, or cost reduction, the content of abrasive particles in the concentrate can be, for example, set to 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).

[0140] In various methods, the content of alkaline compounds in the above-mentioned concentrate can be, for example, set to less than 15% by weight. From the viewpoint of storage stability, the content is generally preferably 10% by weight or less (e.g., less than 10% by weight), more preferably 3% by weight or less, and can be 1% by weight or less (e.g., less than 1% by weight), or 0.5% by weight or less. Furthermore, from the viewpoint of convenience in manufacturing, distribution, and storage, or cost reduction, the content of alkaline compounds in the concentrate can be, for example, set to 0.005% by weight or more, preferably 0.01% by weight or more, more preferably 0.05% by weight or more, and even more preferably 0.1% by weight or more.

[0141] In various methods, the total content (total amount) of water-soluble polymers in the above-mentioned concentrate can be, for example, set at 3% by weight or less. From the viewpoint of the filterability or washability of the grinding composition, the above-mentioned content is generally preferably 1% by weight or less, more preferably 0.5% by weight or less. Furthermore, from the viewpoint of convenience in manufacturing, distribution, and storage, or cost reduction, the above-mentioned content is generally appropriate to be 0.001% by weight or more, preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and even more preferably 0.1% by weight or more.

[0142] In the method of including a surfactant in the grinding composition, the content of the surfactant in the above-mentioned concentrate may be, for example, 0.25% by weight or less, preferably 0.15% by weight or less, more preferably 0.1% by weight or less, and may be 0.05% by weight or less or 0.025% by weight or less. Furthermore, the content of the surfactant in the above-mentioned concentrate may be, for example, 0.0001% by weight or more, preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and even more preferably 0.01% by weight or more.

[0143] <Preparation of Grinding Compositions>

[0144] The grinding composition used in this disclosure can be a single-agent form or a multi-agent form, primarily consisting of two agents. For example, it can be configured by mixing part A, which contains at least abrasive particles from the components of the grinding composition, with part B, which contains at least a portion of the remaining components, and mixing and diluting as needed at appropriate times to prepare a grinding fluid.

[0145] The method for preparing the grinding composition is not particularly limited. For example, known mixing devices such as a wing mixer, an ultrasonic disperser, or a homogenizer can be used to mix the components constituting the grinding composition. The manner in which such components are mixed is not particularly limited; for example, all components can be mixed together, or mixed in a suitably set order.

[0146] <Application>

[0147] The polishing composition disclosed herein is applied to polishing surfaces formed of silicon materials (generally, polishing silicon wafers). Specific examples of silicon materials include monocrystalline silicon, amorphous silicon, and polycrystalline silicon. The polishing composition disclosed herein is particularly preferably used for polishing surfaces formed of monocrystalline silicon (e.g., polishing silicon wafers).

[0148] The polishing composition disclosed herein is preferably applicable to the polishing step of a substrate (e.g., a silicon wafer). Prior to the polishing step using the polishing composition disclosed herein, the substrate can be subjected to general processing that can be applied to the substrate in a step further upstream of the polishing step, such as grinding or etching.

[0149] The polishing composition disclosed herein is effective in fine polishing steps of substrates (e.g., silicon wafers) or in polishing steps immediately preceding them, and is particularly preferred for use in fine polishing steps. Here, a fine polishing step refers to the final polishing step in the manufacturing process of the target object (i.e., a step after which no further polishing is performed). The polishing composition disclosed herein is also used in polishing steps upstream of fine polishing (referring to pre-polishing steps between coarse polishing and final polishing steps, typically including at least one polishing step, and further including two, three, etc. polishing steps), for example, in polishing steps performed immediately preceding fine polishing.

[0150] The polishing composition disclosed herein is effective for polishing (typically fine polishing or polishing immediately preceding it) of silicon wafers whose surface condition has been adjusted to a surface roughness of 0.01 nm to 100 nm via upstream steps. It is particularly preferred for fine polishing. 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 System Inc.

[0151] <Grinding>

[0152] The polishing composition disclosed herein can, for example, be used for polishing a substrate in a manner that includes the following operations. A suitable method for polishing a silicon wafer as a substrate using the polishing composition disclosed herein will be described below.

[0153] That is, a grinding slurry comprising any of the grinding compositions disclosed herein is prepared. The preparation of the grinding slurry may include operations such as adjusting the concentration (e.g., dilution) and pH of the grinding composition. Alternatively, the grinding composition may be used directly as a grinding slurry.

[0154] Next, the polishing slurry is supplied to the substrate, and polishing is performed using conventional methods. For example, in the case of finishing polishing of a silicon wafer, typically, the silicon wafer that has undergone the polishing step is placed in a general polishing apparatus, and polishing slurry is supplied to the polishing target surface of the silicon wafer via the polishing pad of the apparatus. Typically, the polishing slurry is continuously supplied while the polishing pad is pressed against the polishing target surface of the silicon wafer, and the two are moved relative to each other (e.g., rotated). After this polishing step, the polishing of the substrate is completed.

[0155] The abrasive pads used in the above abrasive steps are not particularly limited. Abrasive pads such as polyurethane foam, non-woven fabric, and suede can be used. Each abrasive pad may or may not contain abrasive particles. Generally, abrasive-free abrasive pads are preferred.

[0156] The substrate polished using the polishing composition of this disclosure is typically cleaned. Cleaning can be performed using a suitable cleaning solution. The cleaning solution used is not particularly limited; for example, in the semiconductor field, general SC-1 cleaning solution (a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2), and water (H2O)), SC-2 cleaning solution (a mixture of HCl, H2O2, and H2O), ozone water cleaning solution, hydrofluoric acid cleaning solution, etc., can be used. The temperature of the cleaning solution can be set in the range of, for example, room temperature (typically about 15°C to 25°C) to about 90°C. From the viewpoint of improving the cleaning effect, a cleaning solution with a temperature of about 50°C to 85°C is preferably used.

[0157] As described above, the technology disclosed herein may include a method for manufacturing an abrasive (e.g., a method for manufacturing a silicon wafer) that includes a polishing step (preferably fine polishing) using any of the above-described grinding methods, and an abrasive (e.g., a silicon wafer) manufactured by the method.

[0158] The following matters are disclosed in this specification.

[0159] [1] An abrasive composition for abrading surfaces formed of silicon material.

[0160] The grinding composition comprises abrasive grains (A), an alkaline compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) having a different chemical structure from the first water-soluble polymer (C1).

[0161] The aforementioned first water-soluble polymer (C1) is a random copolymer containing vinyl alcohol units and N-vinylpyrrolidone units.

[0162] [2] The grinding composition according to [1], wherein the aforementioned second water-soluble polymer (C2) is selected from at least one of the group consisting of cellulose derivatives, starch derivatives, polymers containing oxyalkylene units, polyvinyl alcohol polymers, polymers containing nitrogen atoms and carboxylic acid polymers.

[0163] [3] The grinding composition according to [1] or [2], wherein, by weight, 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.

[0164] [4] The grinding composition according to any one of [1] to [3], wherein the weight-average molecular weight of the aforementioned first water-soluble polymer (C1) is 2 × 10⁻⁶. 4 the following.

[0165] [5] The grinding composition according to any one of [1] to [4] comprises silica particles as the aforementioned abrasive (A).

[0166] [6] The grinding composition according to any one of [1] to [5] further comprises a surfactant (D).

[0167] [7] A concentrate of a grinding composition as described in any one of [1] to [6].

[0168] [8] A grinding method comprising grinding a surface formed of silicon material using a grinding composition as described in any one of [1] to [7].

[0169] Example

[0170] The following describes several embodiments of the present invention; however, it is not intended to limit the invention to the contents disclosed in these embodiments. It should be noted that, unless otherwise specified, "parts" and "%" in the following description refer to weight.

[0171] <Preparation of Grinding Compositions>

[0172] (Example 1)

[0173] A concentrated solution of the grinding composition in this example was prepared by mixing abrasive particles, an alkaline 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 particles. Ammonia was used as the alkaline compound. The Mw of the compound, which contains vinyl alcohol units and N-vinylpyrrolidone units, was approximately 3.0 × 10⁻⁶. 4 The random copolymer (poly(VA-r-VP); the first water-soluble polymer), with approximately 35 × 10 4 Polyacrylamide morpholine (PACMO; second water-soluble polymer) was used as the water-soluble polymer. Polyoxyethylene decyl ether (C10EO5), with an addition molar amount of 5 to ethylene oxide, was used as the surfactant. The resulting grinding composition was diluted with deionized water to a volume ratio of 40 times, and the concentrations of abrasive particles, basic compound, poly(VA-r-VP), PACMO, and C10EO5 were set to 0.13%, 0.01%, 0.003%, 0.004%, and 0.001%, respectively, to obtain the grinding composition of this example.

[0174] (Example 2)

[0175] Using approximately 27×10 Mw 4 Poly-N-vinylacetamide (PNVA) was used as the second water-soluble polymer. The grinding composition of this example was prepared in the same manner as in Example 1.

[0176] (Example 3)

[0177] Using Mw is approximately 1.4 × 10 4 The random copolymer (poly(VA-r-VP)) was used as the first water-soluble polymer. The grinding composition of this example was prepared in the same manner as in Example 1.

[0178] (Example 4)

[0179] A random copolymer (poly(VA-r-VP)) with a Mw of about 3,000 was used as the first water-soluble polymer. The grinding composition of this example was prepared in the same manner as in Example 1.

[0180] (Comparative Example 1)

[0181] Using Mw is approximately 1.4 × 10 4 Acetaldehyde-modified polyvinyl alcohol (ac-PVA) was used as the first water-soluble polymer. The grinding composition of this example was prepared in the same manner as in Example 1.

[0182] (Comparative Example 2)

[0183] The Mw using units containing vinyl alcohol and N-vinylpyrrolidone is approximately 17.5 × 10⁻⁶ units. 4 The graft copolymer (PVA-g-PVP) was used as the first water-soluble polymer. The grinding composition of this example was prepared in the same manner as in Example 1.

[0184] (Comparative Example 3)

[0185] Poly(VA-r-VP) was used as the water-soluble polymer only, and the second water-soluble polymer was not used. The grinding composition of this example was prepared in the same manner as in Example 1.

[0186] Grinding of silicon wafers

[0187] As a substrate, a commercially available 300mm diameter single-crystal silicon wafer (conductivity: P-type, crystal orientation: ...) that has undergone grinding and etching is prepared. <100> Silicon wafers without COP (Crystal Originated Particles) were pre-polished under the following polishing conditions 1. Pre-polishing was performed using a polishing slurry containing 0.6% abrasive particles (colloidal silica with an average primary particle size of 35 nm) and 0.08% tetramethylammonium hydroxide (TMAH) in deionized water.

[0188] [Grinding Condition 1]

[0189] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0190] Grinding load: 20 kPa

[0191] Platform speed: 20 rpm

[0192] Grinding head (carrier) rotation speed: 20 rpm

[0193] Abrasive pad: Manufactured by Nitta DuPont, product name "SUBA400"

[0194] The grinding slurry supply rate is 1.0 L / min.

[0195] The temperature of the polishing slurry: 20℃

[0196] Platform cooling water temperature: 20℃

[0197] Grinding time: 2 min

[0198] Using the polishing compositions prepared in the examples described above as polishing fluid, the pre-polished silicon wafer was polished under polishing conditions 2, and then polished under polishing conditions 3.

[0199] [Grinding Condition 2]

[0200] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0201] Grinding load: 16 kPa

[0202] Platform speed: 52 rpm

[0203] Grinding head (carrier) rotation speed: 50 rpm

[0204] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0205] The grinding slurry supply rate is 1.5 L / min.

[0206] The temperature of the polishing slurry: 20℃

[0207] Platform cooling water temperature: 20℃

[0208] Grinding time: 2 min

[0209] [Grinding Condition 3]

[0210] Grinding device: Single-blade grinding device model "PNX-332B" manufactured by Okamoto Machinery Manufacturing Co., Ltd.

[0211] Grinding load: 20 kPa

[0212] Platform speed: 52 rpm

[0213] Grinding head (carrier) rotation speed: 50 rpm

[0214] Abrasive pad: Product name "POLYPAS275NX" manufactured by FUJIBO Ehime Co., Ltd.

[0215] The grinding slurry supply rate is 1.5 L / min.

[0216] The temperature of the polishing slurry: 20℃

[0217] Platform cooling water temperature: 20℃

[0218] Grinding time: 2 min

[0219] <Water Repellency Distance Measurement>

[0220] When the polished silicon wafer is removed, the longest distance in the radial direction from the water-repellent region at the wafer end (water-repellent distance) is measured. The measured value (mm) is converted to a relative value with the measured value (mm) of Comparative Example 1 set as 100%, and the resulting values ​​are listed in the corresponding column of Table 1. The smaller the water-repellent distance (%), the better the wettability is evaluated.

[0221] <Wash clean>

[0222] In addition, the polished silicon wafer is taken out of the polishing apparatus and cleaned with an ozone water cleaning solution (for 60 seconds) using a single wafer cleaning machine, then cleaned with an SC-1 cleaning solution and a brush (for 110 seconds), and then a cleaning process consisting of cleaning with an ozone water cleaning solution (for 20 seconds) and cleaning with a hydrofluoric acid cleaning solution (for 15 seconds) as a set is performed 15 times, and further cleaned with an ozone water cleaning solution (for 20 seconds). After that, the silicon wafer is dried.

[0223] <LPD measurement>

[0224] Using a wafer inspection apparatus manufactured by KLA-Tencor Corporation, trade name "Surfscan SP5", the number of LPDs present on the surface of the cleaned silicon wafer is measured in the Oblique mode of the same apparatus. The measured value is converted to a relative value when the number of LPDs in Comparative Example 1 is set to 100%, and the obtained value is recorded in the corresponding column of Table 1.

[0225] [Table 1]

[0226]

[0227] As shown in Table 1, in the polishing composition containing abrasive grains, an alkaline compound, and two water-soluble polymers, in Examples 1 to 4 using a random copolymer containing VA units and VP units as the water-soluble polymer, compared with Comparative Example 1 that does not use a random copolymer containing VA units and VP units as the water-soluble polymer, the water repellent distance is significantly reduced and the LPD is also decreased. In Comparative Example 2 using a PVA-PVP graft copolymer as one of the two water-soluble polymers, although the LPD can be reduced, the water repellent distance increases, and it is confirmed that there is a tendency for the wettability to deteriorate. In Comparative Example 3 using only one poly(VA-r-VP) as the water-soluble polymer, although the water repellent distance is small, the LPD cannot be reduced.

[0228] The specific examples of the present invention have been described in detail above. However, these are merely illustrative and do not limit the claims. The technology described in the claims includes the technology obtained by various modifications and changes of the above-described specific examples.< / ph>

Claims

1. A polishing composition for polishing surfaces formed of silicon material. The grinding composition comprises abrasive grains (A), an alkaline compound (B), a first water-soluble polymer (C1), and a second water-soluble polymer (C2) having a different chemical structure from the first water-soluble polymer (C1). The first water-soluble polymer (C1) is a random copolymer containing vinyl alcohol units and N-vinylpyrrolidone units.

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

3. The grinding composition according to claim 1 or 2, wherein, On a weight basis, the content of the second water-soluble polymer (C2) relative to the content of the first water-soluble polymer (C1) is 0.1 or more and 20 or less.

4. The grinding composition according to claim 1 or 2, wherein, The weight-average molecular weight of the first water-soluble polymer (C1) is 2 × 10⁻⁶. 4 the following.

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

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

7. A concentrate of the grinding composition according to claim 1 or 2.

8. A polishing method comprising polishing a surface formed of silicon material using the polishing composition of claim 1 or 2.

Images