WO2024203749A1 - Polishing composition - Google Patents

Abstract

Provided is a polishing composition with which surface roughness after polishing can be improved. Also provided is a polishing composition used for polishing a surface composed of a silicon material. This polishing composition comprises abrasive grains and a water-soluble polymer, wherein the abrasive grains includes organic particles. In some aspects, the organic particles may be one or more types of particles selected from among an acrylic resin, a styrene resin, a styrene-acrylic resin, a polyamide resin, a polyimide resin, an epoxy resin, a polyester resin, a polyurethane resin, a phenolic resin, a melamine resin, a benzoguanamine resin, a polyethersulfone resin, and a polytetrafluoroethylene resin.

Description

Polishing composition

The present invention relates to a polishing composition. This application claims priority to Japanese Patent Application No. 2023-56598, filed on March 30, 2023, the entire contents of which are incorporated herein by reference.

Precision polishing using polishing compositions is performed on the surfaces of materials such as metals, semi-metals, non-metals, and their oxides. For example, the surface of silicon wafers used as components of semiconductor devices is generally finished to a high-quality mirror surface through a lapping process (rough polishing process) and a polishing process (precision polishing process). The polishing process typically includes a preliminary polishing process (preliminary polishing process) and a finish polishing process (final polishing process). Patent Document 1 is an example of a technical document related to polishing compositions used for polishing semiconductor substrates such as silicon wafers and other substrates.

Japanese Patent No. 6446590

In the polishing of semiconductor substrates such as silicon wafers and other substrates as described above, abrasive grains with mechanical polishing action have been used to increase the processing power. In particular, in the polishing of silicon wafers, inorganic particles such as silica particles are generally selected and used as abrasive grains that can realize a polished surface of good quality in addition to an appropriate processing power. On the other hand, in response to the recent demand for high-quality polished surfaces, it would be beneficial to provide a polishing composition that can further improve the quality of the polished surface, such as further reducing the surface roughness after polishing.

The present invention aims to provide a polishing composition that can improve surface roughness after polishing.

According to the present specification, a polishing composition is provided for use in polishing a surface made of a silicon material. The polishing composition includes an abrasive and a water-soluble polymer, and the abrasive includes organic particles. Compared to inorganic particles such as silica particles, organic particles tend to be softer and less hard. A polishing composition that includes such organic particles as abrasive particles and further uses a water-soluble polymer that has a protective effect on the polished surface makes it easy to reduce (improve) the surface roughness of the polished surface when polishing a surface made of a silicon material. In addition, the reduction in surface roughness of the polished surface when polishing a surface made of a silicon material can be evaluated by the reduction in haze of the polished surface. Therefore, it can be said that the polishing composition of the above configuration makes it easy to reduce the haze of the polished surface when polishing a surface made of a silicon material.

In some embodiments, the organic particles are one or more types of particles selected from acrylic resin, styrene resin, styrene-acrylic resin, polyamide resin such as nylon resin, polyimide resin, epoxy resin, polyester resin, polyurethane resin, phenol resin, melamine resin, benzoguanamine resin, polyethersulfone resin, and polytetrafluoroethylene resin. By including such organic particles as abrasive grains, the effects of the technology disclosed herein can be preferably achieved.

In some embodiments, the organic particles have an average particle size of less than 5 μm. Using organic particles that are less than the upper limit above tends to improve the abrasive grain dispersion in the polishing composition.

In some embodiments, the polishing composition contains a vinyl alcohol-based polymer as the water-soluble polymer. In a composition containing such a water-soluble polymer and organic particles as abrasive grains, the effects of the present invention can be preferably achieved.

In some embodiments, the content of the water-soluble polymer is 0.5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the abrasive grains.

In some embodiments, the polishing composition further contains a basic compound. With such a polishing composition, the object to be polished tends to be polished efficiently due to the chemical polishing action of the basic compound.

In some embodiments, the polishing composition further contains a surfactant. With this configuration, the surface quality after polishing tends to be improved. In a preferred embodiment, the surfactant is a nonionic surfactant.

The polishing composition disclosed herein may be a concentrated liquid. The polishing composition disclosed herein may be manufactured, distributed, and stored as a concentrated liquid.

In some embodiments, a polishing method is provided that includes polishing a surface made of a silicon material with the polishing composition. The polishing method can achieve a high-quality surface while maintaining the polishing rate.

The following describes preferred embodiments of the present invention. Note that matters other than those specifically mentioned in this specification that are necessary for implementing the present invention can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field.

In this specification, "organic particles" refer to particles that contain an organic substance. In some preferred embodiments, the organic particles are particles that contain an organic substance as a main component. Here, in this specification, "main component" refers to a component that accounts for more than 50% by weight of the total. The organic particles may have a solubility in water at 25°C of 5 g/100 mL or less. The organic substance may be a polymer (typically a resin) that contains carbon.

<Abrasive grain>
The polishing composition disclosed herein is characterized by containing organic particles as abrasive grains. By including abrasive grains in the polishing composition, the polishing rate can be improved based on the mechanical polishing action due to the inclusion of abrasive grains. The reason why the surface roughness is reduced by using organic particles as abrasive grains is not particularly limited, but is thought to be as follows. Organic particles tend to be softer and less hard than inorganic particles such as silica particles. By using such organic particles as abrasive grains, it is thought that the damage given to the polishing surface when the polishing surface and the abrasive grains come into contact during polishing is reduced, and the surface roughness after polishing is easily reduced.

The organic particles are preferably composed of a polymer (typically a resin) containing carbon as a main component. The material constituting the organic particles may be a thermoplastic resin or a thermosetting resin.
Examples of the thermoplastic resin include general-purpose resins; engineering resins; and the like. Examples of the general-purpose resins include polyolefin resins such as polyethylene and polypropylene; polyethylene-vinyl acetate resins; acrylic resins such as polymethyl methacrylate (PMMA), polymethacrylic acid, and polyacrylic acid; styrene resins; styrene-acrylic resins; saturated polyester resins such as polyethylene terephthalate (PET); and vinyl chloride resins. The engineering resins may be general-purpose engineering resins or super engineering resins. Examples of the general-purpose engineering resins include polyamide resins such as nylon resins; polyacetal resins; polycarbonate resins; and the like. Examples of the super engineering resins include fluororesins such as polytetrafluoroethylene (PTFE) resins; polysulfone resins; polyethersulfone (PES) resins; thermoplastic polyimide resins; and the like.
Examples of the thermosetting resin include phenol resin, melamine resin, amino resin, epoxy resin, urea resin, unsaturated polyester resin, polyurethane resin, thermosetting polyimide resin, and benzoguanamine resin.

The material constituting the organic particles may be an addition polymerization resin, a condensation polymerization resin, or other lubricating resin. Examples of addition polymerization resins include acrylic resin, styrene resin, and styrene-acrylic resin. Examples of condensation polymerization resins include polyamide resins such as nylon resin, polyimide resin, epoxy resin, polyester resin, polyurethane resin, phenol resin, melamine resin, benzoguanamine resin, and polyethersulfone resin. Examples of other lubricating resins include polytetrafluoroethylene resin.

As the organic particles, one of the particles made of these materials may be used alone, or two or more of them may be used in combination. In some embodiments, it is preferable to use an acrylic resin containing a (meth)acrylic acid ester as a monomer component as the organic particles.

The organic particles may be charged or uncharged. Anionic, cationic, nonionic, or amphoteric particles may be used as the organic particles. At least one functional group selected from anionic, cationic, amphoteric, and nonionic functional groups may be introduced to the surface of the organic particles. Examples of anionic functional groups include carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type, and examples of cationic functional groups include amine salt type and quaternary ammonium salt type. Examples of amphoteric functional groups include alkanolamide type, carboxybetaine type, and glycine type, and examples of nonionic functional groups include ether type and ester type.

In some embodiments, the material constituting the organic particles is an anionic acrylic resin or a cationic acrylic resin. In other embodiments, the material constituting the organic particles is an anionic styrene-acrylic resin.

The resin constituting the organic particles may be either a resin that is a crosslinked product obtained by mixing and reacting a base agent with a curing agent (crosslinked resin) or a non-crosslinked resin (non-crosslinked resin). The base agent is the above-mentioned resin (e.g., acrylic resin). The curing agent is not particularly limited, but may be, for example, an epoxy compound, an isocyanate compound, or an alkyl etherified melamine resin. In some embodiments, the material constituting the organic particles is a crosslinked acrylic resin or a non-crosslinked acrylic resin. In other embodiments, the material constituting the organic particles is a crosslinked styrene-acrylic resin or a non-crosslinked styrene-acrylic resin.

The organic particles may be prepared by a known method, or may be selected from commercially available products available from various manufacturers, and may be selected from those having particle size, shape, properties, etc. suitable as abrasives for polishing a substrate or other object to be polished (typically a silicon wafer). For example, acrylic resin particles may be selected from commercially available products available from Nippon Paint, DIC, Aica Kogyo, etc. Styrene resin particles may be selected from commercially available products available from Nippon Paint, etc. Styrene-acrylic resin particles may be selected from commercially available products available from Nippon Shokubai, Nippon Paint, etc. Nylon resin particles may be selected from commercially available products available from Toray, etc. Epoxy resin particles may be selected from commercially available products available from Toray, etc. Saturated polyester resin particles may be selected from commercially available products available from Unitika, Sekisui Chemical, etc. Polyurethane resin particles may be selected from commercially available products available from Aica Kogyo, etc. The phenolic resin particles can be selected from commercially available products available from Air Water, Sumitomo Bakelite, etc. The benzoguanamine resin particles can be selected from commercially available products available from Nippon Shokubai, etc. The PES resin particles can be selected from commercially available products available from Japan Material Technology Institute, etc. The PTFE resin particles can be selected from commercially available products available from Techno Chemical, etc. Such abrasive grains can be used alone or in combination of two or more types.

The average particle size of the organic particles is not particularly limited. From the viewpoint of particle dispersibility in the polishing composition, etc., the average particle size of the organic particles is preferably less than 5 μm (e.g., 1 μm or less), more preferably 500 nm or less, and even more preferably 400 nm or less. From the viewpoint of making it easier to obtain a surface with lower haze, in some embodiments, the average particle size of the organic particles may be 300 nm or less, 200 nm or less, 180 nm or less, 165 nm or less, or 150 nm or less. From the viewpoint of polishing rate, etc., the average particle size of the organic particles is preferably 15 nm or more, more preferably 20 nm or more, even more preferably 50 nm or more, and may be 75 nm or more.

The method for measuring the average particle diameter of organic particles is not particularly limited, and any known method appropriate to the particle diameter can be used. For example, the median diameter in the particle size distribution measured by a laser diffraction scattering method can be used as the average particle diameter of the organic particles. In addition, when using commercially available organic particles, the manufacturer's nominal value (catalog value) can be used as the average particle diameter of the organic particles.

In some embodiments, the organic particles can be in the form of a dispersion, emulsion, powder, etc. From the viewpoint of particle dispersibility in the polishing composition, in a preferred embodiment of the technology disclosed herein, the organic particles can be in the form of an aqueous dispersion.

The polishing composition disclosed herein may contain particles other than organic particles (hereinafter also referred to as "non-organic particles") as abrasive grains to the extent that the effects of the invention are not significantly hindered. Examples of non-organic particles include inorganic particles. Specific examples of inorganic particles include oxide particles such as silica particles, alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate, and the like. Such non-organic particles may be used alone or in combination of two or more types. In some embodiments, silica particles (typically colloidal silica) may be used as the non-organic particles.

In some preferred embodiments, organic particles and inorganic particles as abrasives are used in combination. By using a combination of organic particles and inorganic particles, the surface roughness after polishing is more likely to be reduced than when only inorganic particles are used. In addition, by using a combination of organic particles and inorganic particles, defects after polishing tend to be more likely to be reduced than when only organic particles are used. When using organic particles and inorganic particles in combination, one or more types selected from the specific examples of inorganic particles disclosed herein can be suitably used as the inorganic particles. In some embodiments, particles made of a metal or semi-metal oxide are preferred as the inorganic particles, and silica particles are particularly preferred.

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

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 typically 2.3 or less, for example 2.2 or less. The true specific gravity of the silica particles can be measured by a liquid substitution method using ethanol as the substitution liquid.

The average primary particle diameter of the inorganic particles (typically silica particles, preferably colloidal silica) used together with the organic particles is not particularly limited, but from the viewpoint of polishing rate, etc., it is preferably 5 nm or more, more preferably 10 nm or more. From the viewpoint of obtaining a higher polishing effect (e.g., effects such as reducing haze and removing defects), the average primary particle diameter is preferably 15 nm or more, and more preferably 20 nm or more (e.g., more than 20 nm). From the viewpoint of preventing scratches, etc., the average primary particle diameter of the inorganic particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 45 nm or less. From the viewpoint of making it easier to obtain a surface with a lower haze, in some embodiments, the average primary particle diameter of the inorganic particles may be 43 nm or less, may be less than 40 nm, may be less than 38 nm, may be less than 35 nm, may be less than 32 nm, or may be less than 30 nm.

In this specification, the average primary particle size of inorganic particles refers to the particle size (BET particle size) calculated from the specific surface area (BET value) measured by the BET method using the formula: average primary particle size (nm) = 6000/(true density (g/ ^cm3 ) x BET value ( ^m2 /g)). The specific surface area can be measured, for example, using a surface area measuring device manufactured by Micromeritics, product name "Flow Sorb II 2300".

The average secondary particle diameter of the inorganic particles (typically silica particles, preferably colloidal silica) used together with the organic particles is not particularly limited and may be appropriately selected, for example, from the range of about 15 nm to 300 nm. From the viewpoint of improving the polishing rate, the average secondary particle diameter is preferably 30 nm or more, and more preferably 35 nm or more. In some embodiments, the average secondary particle diameter may be, for example, 40 nm or more, 42 nm or more, and preferably 44 nm or more. In addition, the average secondary particle diameter is usually advantageously 250 nm or less, preferably 200 nm or less, and more preferably 150 nm or less. In some preferred embodiments, the average secondary particle diameter is 120 nm or less, more preferably 100 nm or less, and even more preferably 70 nm or less, for example, 60 nm or less, or 50 nm or less.

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

The shape (outer shape) of the inorganic particles (typically silica particles, preferably colloidal silica) may be spherical or non-spherical. Specific examples of non-spherical particles include peanut-shaped (i.e., peanut shell-shaped), cocoon-shaped, confetti-shaped, and rugby ball-shaped. For example, silica particles in which most of the particles are peanut-shaped or cocoon-shaped may be preferably used.

Although not particularly limited, the average value of the long axis/short axis ratio (average aspect ratio) of inorganic particles (typically silica particles, preferably colloidal silica) is in principle 1.0 or more, preferably 1.05 or more, more preferably 1.1 or more, and may be 1.2 or more. By increasing the average aspect ratio, a higher polishing rate can be realized. Furthermore, from the viewpoint of reducing scratches, etc., the average aspect ratio of inorganic particles (typically silica particles, preferably colloidal silica) is preferably 3.0 or less, more preferably 2.0 or less, even more preferably 1.5 or less, and may be 1.4 or less.

The shape (outer shape) and average aspect ratio of inorganic particles (typically silica particles, preferably colloidal silica) can be determined, for example, by observation with an electron microscope. A specific procedure for determining the average aspect ratio is, for example, to use a scanning electron microscope (SEM) to draw the smallest rectangle circumscribing each particle image for a predetermined number (e.g., 200) of inorganic particles whose individual particle shapes can be recognized. Then, for the rectangle drawn for each particle image, the long side length (long axis value) is divided by the short side length (short axis value) to calculate the long axis/short axis ratio (aspect ratio). The average aspect ratio can be obtained by arithmetically averaging the aspect ratios of the above-mentioned predetermined number of particles.

When organic particles and inorganic particles are used in combination, the content ratio of organic particles to inorganic particles is not particularly limited.From the viewpoint of reducing surface roughness (reducing haze), the weight ratio (W _INO /W _O ) of the content W _INO of inorganic particles to the content W _O of organic particles may be, for example, 99 or less, 75 or less, 50 or less, 30 or less, 15 or less, 10 or less, 7.0 or less, 5.0 or less, 4.0 or less, or 3.5 or less. From the viewpoint of reducing defects, the weight ratio (W _INO /W _O ) of the inorganic particle content W _INO to the organic particle content W _O may be, for example, 0.03 or more, 0.05 or more, 0.1 or more, preferably 0.5 or more, more preferably 1.0 or more (e.g., greater than 1), 1.25 or more, 1.5 or more, 1.75 or more, 2.0 or more, 2.25 or more, 2.5 or more, or 2.75 or more.

When organic particles and inorganic particles are used in combination, from the viewpoint of reducing surface roughness (reducing haze), the proportion of organic particles in the total amount of abrasive grains may be, for example, 1 weight % or more, 3 weight % or more, preferably 5 weight % or more, more preferably 10 weight % or more, 15 weight % or more, 20 weight % or more, or 22 weight % or more. From the viewpoint of reducing defects, the proportion of organic particles in the total amount of abrasive grains may be, for example, 97 weight % or less, 90 weight % or less, 80 weight % or less, 70 weight % or less, 60 weight % or less, 50 weight % or less, 40 weight % or less, or 30 weight % or less.

When organic particles and inorganic particles are used in combination, the average particle size of the organic particles and the average primary particle size of the inorganic particles may satisfy a predetermined relationship from the viewpoint of reducing surface roughness (reducing haze). The ratio of the average primary particle size of the inorganic particles to the average particle size of the organic particles may be, for example, 0.002 or more, 0.005 or more, or 0.01 or more. The ratio of the average primary particle size of the inorganic particles to the average particle size of the organic particles may be, for example, 1 or less, 0.8 or less, 0.6 or less, or 0.5 or less.

When organic particles and inorganic particles are used in combination, the number concentration of organic particles and the number concentration of inorganic particles may satisfy a predetermined relationship from the viewpoint of reducing surface roughness (reducing haze). In the polishing composition, the ratio of the number (number concentration) Nip [pieces/L] of inorganic particles to the number (number concentration) Nrp [pieces/L] of organic particles, i.e., Nip/Nrp, may be, for example, 1.0×10 ⁻⁵ or more, 1.0×10 ⁻³ or more, 1.0×10 ⁻¹ or more, 1.0×10 or more, or 5.0×10 or more. Nip/Nrp may be, for example, 5.1×10 ⁹ or less, 1.0×10 ⁸ or less, 1.0×10 ⁶ or less, 1.0×10 ⁴ or less, or 1.0×10 ³ or less.
In the above "Nip/Nrp", "Nip" represents the numerical value when the number concentration of inorganic particles in the polishing composition is expressed in units of "pieces/L", and "Nrp" represents the numerical value when the number concentration of organic particles in the polishing composition is expressed in units of "pieces/L", and both Nip and Nrp are dimensionless numbers.

The number concentration of the inorganic particles is calculated by the formula: number concentration of inorganic particles (pieces/L) = concentration of inorganic particles in polishing composition (g/L) / weight per inorganic particle (g/piece). Here, the weight per inorganic particle is calculated by the formula: weight per inorganic particle (g/piece) = (4/3) x π x (radius of inorganic particle (m)) ³ x density of inorganic particle (g/m ³ ). The number concentration of the organic particles can be calculated in the same manner. The radius of the inorganic particles is 1/2 the value of the average primary particle diameter of the inorganic particles. The radius of the organic particles is 1/2 the value of the average particle diameter of the organic particles.

The technology disclosed herein can also be preferably implemented in an embodiment in which substantially only organic particles are used as abrasive grains. From this perspective, the proportion of organic particles in the total amount of abrasive grains is appropriately 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight or more (for example, 99 to 100% by weight).

<Water-soluble polymer>
The polishing composition disclosed herein includes a water-soluble polymer. The water-soluble polymer can be useful for protecting the surface to be polished and improving the wettability of the surface to be polished after polishing. By including a water-soluble polymer in the polishing composition, the surface quality after polishing (e.g., haze) can be improved. According to the technology disclosed herein, a composition containing organic particles as abrasive grains and a water-soluble polymer can more suitably improve the surface roughness after polishing. In some embodiments, the water-soluble polymer can be a compound containing a hydroxyl group, a carboxyl group, an acyloxy group, a sulfo group, an amide structure, an imide structure, a quaternary ammonium structure, a heterocyclic structure, a vinyl structure, or the like in the molecule. As the water-soluble polymer, for example, a cellulose derivative, a starch derivative, a polymer containing an oxyalkylene unit, a polyvinyl alcohol-based polymer, a polymer containing a nitrogen atom, or the like can be used. The water-soluble polymer may be a polymer derived from a natural product or a synthetic polymer. The water-soluble polymer may be used alone or in combination of two or more types.

In some embodiments, a polymer derived from a natural product is used as the water-soluble polymer. Examples of the polymer derived from a natural product include cellulose derivatives and starch derivatives. The polymer derived from a natural product may be used alone or in combination of two or more types.

In some embodiments, a cellulose derivative is used as the water-soluble polymer. Here, the cellulose derivative is a polymer containing β-glucose units as the main repeating unit. Specific examples of cellulose derivatives include hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose, etc. Among these, HEC is preferred. The cellulose derivatives may be used alone or in combination of two or more.

In some embodiments, a starch derivative is used as the water-soluble polymer. Starch derivatives are polymers that contain α-glucose units as the main repeating unit, and examples of such polymers include pregelatinized starch, pullulan, carboxymethyl starch, and cyclodextrin. Starch derivatives may be used alone or in combination of two or more types.

In some preferred embodiments, a synthetic polymer is used as the water-soluble polymer. The effects of the technology disclosed herein are preferably exhibited in embodiments in which a synthetic polymer is used as the water-soluble polymer. The synthetic polymer may be used alone or in combination of two or more types.

In some embodiments, a polymer containing an oxyalkylene unit is used as the water-soluble polymer. Examples of the polymer containing an oxyalkylene unit include polyethylene oxide (PEO), block copolymers of ethylene oxide (EO) and propylene oxide (PO) or butylene oxide (BO), and random copolymers of EO and PO or BO. Among these, block copolymers of EO and PO or random copolymers of EO and PO are preferred. The block copolymer of EO and PO may be a diblock copolymer containing a PEO block and a polypropylene oxide (PPO) block, or a triblock copolymer. Examples of the triblock copolymer include PEO-PPO-PEO type triblock copolymers and PPO-PEO-PPO type triblock copolymers. Usually, PEO-PPO-PEO type triblock copolymers are more preferred.

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

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

In some preferred embodiments, a polyvinyl alcohol-based polymer is used as the water-soluble polymer. A composition containing a polyvinyl alcohol-based polymer can improve the polishing rate while maintaining the surface quality after polishing. A polyvinyl alcohol-based polymer refers to a polymer containing vinyl alcohol units (hereinafter also referred to as "VA units") as its repeating units. A single type of polyvinyl alcohol-based polymer may be used alone, or two or more types may be used in combination. A polyvinyl alcohol-based polymer may contain only VA units as repeating units, or may contain VA units and repeating units other than VA units (hereinafter also referred to as "non-VA units"). A polyvinyl alcohol-based polymer may be a random copolymer containing VA units and non-VA units, a block copolymer, an alternating copolymer, or a graft copolymer. A polyvinyl alcohol-based polymer may contain only one type of non-VA unit, or may contain two or more types of non-VA units.

The polyvinyl alcohol-based polymer may be unmodified polyvinyl alcohol (unmodified PVA) or modified polyvinyl alcohol (modified PVA). Unmodified PVA refers to a polyvinyl alcohol-based polymer that is produced by hydrolysis (saponification) of polyvinyl acetate and does not substantially contain repeating units other than repeating units (-CH ₂ -CH(OCOCH ₃ )-) having a structure in which vinyl acetate is vinyl-polymerized and VA units. The degree of saponification of the unmodified PVA may be, for example, 60% or more, and from the viewpoint of water solubility, may be 70% or more, 80% or more, or 90% or more.

The polyvinyl alcohol-based polymer may be a polymer containing a VA unit and a non-VA unit having at least one structure selected from an oxyalkylene group, a carboxy group, a (di)carboxylic acid group, a (di)carboxylic acid ester group, a phenyl group, a naphthyl group, a sulfo group, an amino group, a hydroxyl group, an amide group, an imide group, a nitrile group, an ether group, an ester group, and a salt thereof. In addition, examples of non-VA units that may be contained in the polyvinyl alcohol-based polymer include, but are not limited to, repeating units derived from N-vinyl type monomers and N-(meth)acryloyl type monomers described below, repeating units derived from ethylene, repeating units derived from alkyl vinyl ethers, repeating units derived from vinyl esters of monocarboxylic acids having 3 or more carbon atoms, and repeating units derived from (di)acetone compounds. One suitable example of the N-vinyl type monomer is N-vinylpyrrolidone. One suitable example of the N-(meth)acryloyl type monomer is N-(meth)acryloylmorpholine. The alkyl vinyl ether may be, for example, a vinyl ether having an alkyl group having 1 to 10 carbon atoms, such as propyl vinyl ether, butyl vinyl ether, or 2-ethylhexyl vinyl ether. The vinyl ester of a monocarboxylic acid having 3 or more carbon atoms may be, for example, a vinyl ester of a monocarboxylic acid having 3 to 7 carbon atoms, such as vinyl propanoate, vinyl butanoate, vinyl pentanoate, or vinyl hexanoate. Suitable examples of the (di)acetone compound include diacetone (meth)acrylamide and acetylacetone. In this specification, "(meth)acryl" refers to acryl and methacryl in a comprehensive sense. Similarly, "(meth)acryloyl" refers to acryloyl and methacryloyl in a comprehensive sense.

In some preferred embodiments, an acetalized polyvinyl alcohol polymer is used as the polyvinyl alcohol polymer. An example of the acetalized polyvinyl alcohol polymer is a polymer in which some of the VA units contained in the polyvinyl alcohol polymer have been acetalized. A modified polyvinyl alcohol polymer in which some of the VA units contained in the polyvinyl alcohol polymer have been acetalized (acetalized PVA (Ac-PVA)) can be obtained by reacting some of the hydroxyl groups of the polyvinyl alcohol polymer with an aldehyde compound or a ketone compound to acetalize the polymer. Typically, the acetalized polyvinyl alcohol polymer is obtained by an acetalization reaction between a polyvinyl alcohol polymer and an aldehyde compound. In some preferred embodiments, the aldehyde compound has 1 to 7 carbon atoms, more preferably 2 to 7 carbon atoms.

Examples of the aldehyde compounds include formaldehyde; linear or branched alkyl aldehydes such as acetaldehyde, propionaldehyde, n-butylaldehyde, isobutylaldehyde, t-butylaldehyde, and hexylaldehyde; and alicyclic or aromatic aldehydes such as cyclohexanecarbaldehyde and benzaldehyde. These may be used alone or in combination of two or more. In addition, with the exception of formaldehyde, one or more hydrogen atoms may be substituted with a halogen or the like. Among these, linear or branched alkyl aldehydes are preferred because of their high solubility in water and ease of acetalization reaction, and among these, acetaldehyde, n-propylaldehyde, n-butylaldehyde, and n-pentylaldehyde are more preferred.

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

The acetalized polyvinyl alcohol-based polymer contains VA units, which are structural moieties represented by the following chemical formula: -CH ₂ -CH(OH)-; and acetalized structural units (hereinafter also referred to as "VAC units") represented by the following general formula (1).

　（式（１）中、Ｒは水素原子、または、直鎖または分枝アルキル基であり、該アルキル基は官能基によって置換されていてもよい。）

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

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

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

In addition, as the polyvinyl alcohol-based polymer, a cation-modified polyvinyl alcohol into which a cationic group such as a quaternary ammonium structure has been introduced may be used. Examples of the cation-modified polyvinyl alcohol include those into which a cationic group derived from a monomer having a cationic group, such as a diallyldialkylammonium salt or an N-(meth)acryloylaminoalkyl-N,N,N-trialkylammonium salt, has been introduced. In addition, as the modified vinyl alcohol-based polymer, the non-VA unit may have a structural portion represented by the chemical formula: -CH ₂ -CH(CR ¹ (OR ⁴ )-CR ² (OR ⁵ )-R ³ )-. Here, R ¹ to R ³ each independently represent a hydrogen atom or an organic group, and R ⁴ and R ⁵ each independently represent a hydrogen atom or R ⁶ -CO- (wherein R ⁶ represents an alkyl group). For example, when at least one of R ¹ to R ³ in the above chemical formula is an organic group, the organic group may be a straight-chain or branched alkyl group having 1 to 8 carbon atoms. Additionally, ^R6 in the above chemical formula can be a linear or branched alkyl group having from 1 to 8 carbon atoms.

In some embodiments, the polyvinyl alcohol polymer is a modified polyvinyl alcohol polymer having a 1,2-diol structure in a side chain, such as a polymer containing non-VA units in which R ¹ to R ⁵ are hydrogen atoms (butenediol-vinyl alcohol copolymer (BVOH)).

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

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

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

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

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

Examples of polyvinyl alcohol-based polymers that contain polymer chain A and polymer chain B in the same molecule include block copolymers and graft copolymers that contain these polymer chains. The above graft copolymers may be graft copolymers having a structure in which polymer chain B (side chain) is grafted to polymer chain A (main chain), or graft copolymers having a structure in which polymer chain A (side chain) is grafted to polymer chain B (main chain). In some embodiments, modified polyvinyl alcohol-based polymers having a structure in which polymer chain B is grafted to polymer chain A can be used.

Examples of polymer chain B include polymer chains whose main repeating units are repeating units derived from N-vinyl type monomers; polymer chains whose main repeating units are repeating units derived from N-(meth)acryloyl type monomers; polymer chains whose main repeating units are repeating units derived from vinyl dicarboxylates such as fumaric acid, maleic acid, and maleic anhydride; polymer chains whose main repeating units are repeating units derived from aromatic vinyl monomers such as styrene and vinylnaphthalene; polymer chains whose main repeating units are oxyalkylene units; and the like. In this specification, the term "main repeating unit" refers to a repeating unit that is contained in an amount of more than 50% by weight, unless otherwise specified.

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

In this specification, examples of N-vinyl type monomers include monomers having a nitrogen-containing heterocycle (e.g., lactam ring) and N-vinyl chain amides. Specific examples of N-vinyl lactam type monomers include N-vinyl pyrrolidone, N-vinyl piperidone, N-vinyl morpholinone, N-vinyl caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, and the like. Specific examples of N-vinyl chain amides include N-vinyl acetamide, N-vinyl propionic acid amide, N-vinyl butyric acid amide, and the like. Polymer chain B may be, for example, an N-vinyl polymer chain in which more than 50% by weight (e.g., 70% by weight or more, 85% by weight or more, or 95% by weight or more) of its repeating units are N-vinyl pyrrolidone units. Substantially all of the repeating units constituting polymer chain B may be N-vinyl pyrrolidone units.

Another example of polymer chain B is a polymer chain whose main repeating unit is a repeating unit derived from an N-(meth)acryloyl type monomer, i.e., an N-(meth)acryloyl-based polymer chain. The content of repeating units derived from N-(meth)acryloyl type monomers in the N-(meth)acryloyl-based polymer chain is typically more than 50% by weight, and may be 70% by weight or more, 85% by weight or more, or 95% by weight or more. Substantially all of polymer chain B may be repeating units derived from N-(meth)acryloyl type monomers.

In this specification, examples of N-(meth)acryloyl type monomers include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group. Examples of linear amides having an N-(meth)acryloyl group include (meth)acrylamide; N-alkyl (meth)acrylamides such as N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide, and N-n-butyl (meth)acrylamide; 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; and N-hydroxyalkyl (meth)acrylamides such as N-hydroxyethyl (meth)acrylamide. Examples of cyclic amides having an N-(meth)acryloyl group include N-(meth)acryloylmorpholine and N-(meth)acryloylpyrrolidine.

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

Examples of oxyalkylene units include oxyethylene units, oxypropylene units, and oxybutylene units. Each of these oxyalkylene units may be a repeating unit derived from the corresponding alkylene oxide. The oxyalkylene units contained in the oxyalkylene polymer chain may be one type, or two or more types. For example, the oxyalkylene polymer chain may contain a combination of oxyethylene units and oxypropylene units. In an oxyalkylene polymer chain containing two or more types of oxyalkylene units, the oxyalkylene units may be a random copolymer, a block copolymer, an alternating copolymer, or a graft copolymer of the corresponding alkylene oxide.

Further examples of polymer chain B include polymer chains containing repeating units derived from alkyl vinyl ethers (e.g., vinyl ethers having an alkyl group with 1 to 10 carbon atoms), polymer chains containing repeating units derived from monocarboxylic acid vinyl esters (e.g., vinyl esters of monocarboxylic acids with 3 or more carbon atoms), and polymer chains into which cationic groups (e.g., cationic groups having a quaternary ammonium structure) have been introduced.

The polyvinyl alcohol-based polymer serving as the water-soluble polymer in the technology disclosed herein is preferably a modified polyvinyl alcohol, which is a copolymer containing VA units and non-VA units. The degree of saponification of the polyvinyl alcohol-based polymer serving as the water-soluble polymer is usually 50 mol% or more, preferably 65 mol% or more, more preferably 70 mol% or more, for example 75 mol% or more. In principle, the degree of saponification of the polyvinyl alcohol-based polymer is 100 mol% or less.

In some preferred embodiments, a polymer containing nitrogen atoms is used as the water-soluble polymer. A polishing composition containing a polymer containing nitrogen atoms makes it easier to obtain a high-quality polished surface. Non-limiting examples of polymers containing nitrogen atoms include polymers containing N-vinyl type monomer units; polymers containing N-(meth)acryloyl type monomer units; and the like. The polymers containing nitrogen atoms may be used alone or in combination of two or more types.

In some embodiments, an N-vinyl type polymer may be used as the water-soluble polymer (polymer containing nitrogen atoms). Examples of N-vinyl type polymers include polymers containing repeating units derived from monomers having a nitrogen-containing heterocycle (e.g., lactam ring). Examples of such polymers include homopolymers and copolymers of N-vinyl lactam type monomers (e.g., copolymers in which the copolymerization ratio of N-vinyl lactam type monomers exceeds 50% by weight), homopolymers and copolymers of N-vinyl linear amides (e.g., copolymers in which the copolymerization ratio of N-vinyl linear amides exceeds 50% by weight), and the like.

Specific examples of N-vinyl lactam type monomers (i.e., compounds having a lactam structure and an N-vinyl group in one molecule) include N-vinyl pyrrolidone (VP), N-vinyl piperidone, N-vinyl morpholinone, N-vinyl caprolactam (VC), N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, etc. Specific examples of polymers containing N-vinyl lactam type monomer units include polyvinyl pyrrolidone, polyvinyl caprolactam, random copolymers of VP and VC, random copolymers of one or both of VP and VC with other vinyl monomers (e.g., acrylic monomers, vinyl ester monomers, etc.), block copolymers, alternating copolymers, graft copolymers, etc. containing polymer chains containing one or both of VP and VC.
Specific examples of the N-vinyl chain amide include N-vinyl acetamide, N-vinyl propionic acid amide, and N-vinyl butyric acid amide.

In some embodiments, an N-(meth)acryloyl type polymer may be preferably used as the water-soluble polymer (polymer containing a nitrogen atom). The effects of the technology disclosed herein may be more preferably realized in a composition containing an N-(meth)acryloyl type polymer. Examples of N-(meth)acryloyl type polymers include homopolymers and copolymers of N-(meth)acryloyl type monomers (typically copolymers in which the copolymerization ratio of N-(meth)acryloyl type monomers exceeds 50% by weight). Examples of N-(meth)acryloyl type monomers include linear amides having an N-(meth)acryloyl group and cyclic amides having an N-(meth)acryloyl group.

Examples of chain amides having an N-(meth)acryloyl group include (meth)acrylamide; N-alkyl (meth)acrylamides such as N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide, and N-n-butyl (meth)acrylamide; and N,N-dialkyl (meth)acrylamides such as N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N,N-dipropyl (meth)acrylamide, N,N-diisopropyl (meth)acrylamide, and N,N-di(n-butyl) (meth)acrylamide. Examples of polymers containing chain amides having an N-(meth)acryloyl group as monomer units include homopolymers of N-isopropylacrylamide and copolymers of N-isopropylacrylamide (for example, copolymers in which the copolymerization ratio of N-isopropylacrylamide exceeds 50% by weight).

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. An example of a polymer containing a cyclic amide having an N-(meth)acryloyl group as a monomer unit is an acryloylmorpholine-based polymer (PACMO). Typical examples of acryloylmorpholine-based polymers include homopolymers of N-acryloylmorpholine (ACMO) and copolymers of ACMO (for example, copolymers in which the copolymerization ratio of ACMO exceeds 50% by weight). In an acryloylmorpholine-based polymer, the ratio of the number of moles of ACMO units to the number of moles of all repeating units is usually 50% or more, and suitably 80% or more (e.g., 90% or more, typically 95% or more). All repeating units of the water-soluble polymer may be substantially composed of ACMO units.

In the technology disclosed herein, the weight average molecular weight (Mw) of the water-soluble polymer is not particularly limited. The Mw of the water-soluble polymer may be, for example, about 200×10 ⁴ or less, and is appropriately about 150×10 ⁴ or less, and from the viewpoint of cleaning properties, it is preferably about 100×10 ⁴ or less, and may be about 50×10 ⁴ or less. In addition, from the viewpoint of protecting the polishing surface, the Mw of the water-soluble polymer is preferably 0.5×10 ⁴ or more. In some embodiments, the Mw is appropriately 1.0×10 ⁴ or more, and may be 2×10 ⁴ or more, for example, 5×10 ⁴ or more.

In the technology disclosed herein, the preferred molecular weight range of the water-soluble polymer compound may vary depending on the type of polymer used. For example, the Mw of the cellulose derivative and the starch derivative can be approximately 200×10 ⁴ or less, and is preferably 150×10 ⁴ or less. The Mw may be approximately 100×10 ⁴ or less, or may be approximately 50×10 ⁴ or less (e.g., approximately 30×10 ⁴ or less). In addition, from the viewpoint of the protection of the polished surface, the Mw is preferably approximately 0.5×10 ⁴ or more, preferably approximately 1.0×10 ⁴ or more, more preferably approximately 3.0×10 ⁴ or more, even more preferably approximately 10×10 ⁴ or more, and may be approximately 20×10 ⁴ or more.

For example, the Mw of the polyvinyl alcohol-based polymer can be 100×10 ⁴ or less, and is suitably 60×10 ⁴ or less. From the viewpoint of concentration efficiency, the Mw may be 30×10 ⁴ or less, preferably 20×10 ⁴ or less, for example, 10×10 ⁴ or less, 8×10 ⁴ or less, 5×10 ⁴ or less, or 3×10 ⁴ or less. When the Mw of the polyvinyl alcohol-based polymer is small, the dispersion stability of the polyvinyl alcohol-based polymer tends to improve. In addition, from the viewpoint of suitably protecting the polished surface and maintaining or improving the surface quality, the Mw is preferably 0.5×10 ⁴ or more. As the Mw of the polyvinyl alcohol-based polymer increases, the effect of protecting the polished object and improving the wettability tends to increase. From such a viewpoint, in some embodiments, the Mw is suitably 0.6×10 ⁴ or more, and preferably 0.8×10 ⁴ or more.

For example, the Mw of a polymer containing a nitrogen atom (for example, an N-(meth)acryloyl type polymer, preferably PACMO) can be 100×10 ⁴ or less, and is suitably 70×10 ⁴ or less. From the viewpoint of concentration efficiency, the Mw may be 60×10 ⁴ or less, or may be 50×10 ⁴ or less. From the viewpoint of maintaining or improving surface quality, the Mw may be, for example, 1.0×10 ⁴ or more, or may be 10×10 ⁴ or more. In some embodiments, the Mw is suitably 20×10 ⁴ or more, preferably 30×10 ⁴ or more, and may be, for example, 40×10 ⁴ or more.
For example, the Mw of the polymer containing an oxyalkylene unit can be 10 x 10 ⁴ or less, 5 x 10 ⁴ or less, 3 x 10 ⁴ or less, or 2 x 10 ⁴ or less. The Mw can be 0.5 x 10 ⁴ or more, 1 x 10 ⁴ or more, 1.2 x 10 ⁴ or more, or 1.5 x 10 ⁴ or more.

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

From the viewpoint of reducing agglomerates and improving washability, etc., a nonionic polymer may be preferably used as the water-soluble polymer. Furthermore, from the viewpoint of ease of control of chemical structure and purity, a synthetic polymer may be preferably used as the water-soluble polymer. For example, when the technology disclosed herein is implemented in an embodiment that includes a synthetic polymer as the water-soluble polymer, the polishing composition may be one that does not substantially use a polymer derived from a natural product as the water-soluble polymer. Here, "substantially not using" means that the amount of the polymer derived from a natural product used per 100 parts by weight of the total content of the water-soluble polymer is typically 3 parts by weight or less, preferably 1 part by weight or less, and includes 0 parts by weight or below the detection limit.

Although not particularly limited, in some embodiments, the content of the water-soluble polymer in the polishing composition (the total amount of two or more water-soluble polymers when two or more types of water-soluble polymers are included) can be, for example, 0.01 parts by weight or more per 100 parts by weight of abrasive grains (typically organic particles), and from the viewpoint of reducing haze, etc., it is appropriate to set it to 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, may be 1.5 parts by weight or more, may be 2 parts by weight or more, may be 3 parts by weight or more, or may be 3.5 parts by weight or more. The content of the water-soluble polymer per 100 parts by weight of abrasive grains may be, for example, 50 parts by weight or less, or may be 30 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of the water-soluble polymer per 100 parts by weight of abrasive grains is appropriate to be 15 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, may be less than 3 parts by weight, may be 2.5 parts by weight or less, or may be 2 parts by weight or less. By appropriately setting the amount of water-soluble polymer used within the above range, a significant improvement in haze after polishing can be achieved.

<Basic Compound>
In some embodiments, the polishing composition preferably contains a basic compound. In this specification, the basic compound refers to a compound that dissolves in water and has the function of increasing the pH of the aqueous solution. By including a basic compound in the polishing composition, the polishing target can be efficiently polished by its chemical polishing action (alkaline etching). As the basic compound, an organic or inorganic basic compound containing nitrogen, a basic compound containing phosphorus, a hydroxide of an alkali metal, a hydroxide of an alkaline earth metal, various carbonates and hydrogen carbonates, etc. can be used. Examples of basic compounds containing nitrogen include quaternary ammonium compounds, ammonia, amines (preferably water-soluble amines), etc. Examples of basic compounds containing phosphorus include quaternary phosphonium compounds. Such basic compounds can be used alone or in combination of two or more.

Specific examples of alkali metal hydroxides include potassium hydroxide and sodium hydroxide.Specific examples of carbonates or hydrogen carbonates include ammonium hydrogen carbonate, ammonium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, and sodium carbonate.Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, guanidine, and azoles such as imidazole and triazole.Specific examples of quaternary phosphonium compounds include quaternary phosphonium hydroxides such as tetramethylphosphonium hydroxide and tetraethylphosphonium hydroxide.

As the quaternary ammonium compound, a quaternary ammonium salt (typically a strong base) such as a tetraalkylammonium salt or a hydroxyalkyltrialkylammonium salt can be used. The anion component in such a quaternary ammonium salt can be, for example, OH ^- , F ^- , Cl ^- , Br ^- , I ^- , ClO ₄ ^- , BH ₄ ^{- ,} etc. Examples of the quaternary ammonium compound include a quaternary ammonium salt whose anion is OH-, that is, a quaternary ammonium hydroxide. Specific examples of the quaternary ammonium hydroxide include tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, and tetrahexylammonium hydroxide; and hydroxyalkyltrialkylammonium hydroxides such as 2-hydroxyethyltrimethylammonium hydroxide (also called choline).

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

<Surfactant>
In some embodiments, the polishing composition preferably contains at least one type of surfactant. By adding a surfactant to the polishing composition, the haze of the polished surface can be reduced. According to the technology disclosed herein, the quality of the polished surface can be further improved by using a composition containing the water-soluble polymer and a surfactant. As the surfactant, any of anionic, cationic, nonionic, and amphoteric surfactants can be used. Usually, anionic or nonionic surfactants can be preferably used. From the viewpoint of low foaming and ease of pH adjustment, nonionic surfactants are more preferable. For example, nonionic surfactants include oxyalkylene polymers such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; polyoxyalkylene derivatives such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene fatty acid esters, polyoxyethylene glyceryl ether fatty acid esters, and polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyalkylene adducts); and copolymers of multiple types of oxyalkylenes (e.g., diblock copolymers, triblock copolymers, random copolymers, and alternating copolymers). The surfactants can be used alone or in combination of two or more.

Specific examples of nonionic surfactants include block copolymers of ethylene oxide (EO) and propylene oxide (PO) (diblock copolymers, PEO (polyethylene oxide)-PPO (polypropylene oxide)-PEO type triblock copolymers, PPO-PEO-PPO type triblock copolymers, etc.), random copolymers of EO and PO, polyoxyethylene glycol, polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene Examples of the polyoxyethylene sorbitan monolaurate include oleyl ether, polyoxyethylene phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene lauryl amine, polyoxyethylene stearyl amine, polyoxyethylene oleyl amine, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalminate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil. Among these, preferred surfactants include block copolymers of EO and PO (particularly triblock copolymers of the PEO-PPO-PEO type), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (e.g., polyoxyethylene decyl ether). As polyoxyethylene alkyl ethers, those with an EO addition mole number of about 1 to 10 (e.g., about 3 to 8) can be preferably used.

In some embodiments, a nonionic surfactant is preferably used. The use of a nonionic surfactant tends to further improve the haze reduction performance.

The molecular weight of the surfactant is, for example, less than 5000, and is preferably 4500 or less from the viewpoint of filterability and washability, and may be, for example, less than 4000. In addition, the molecular weight of the surfactant is usually appropriate to be 200 or more from the viewpoint of surface activity, and is preferably 250 or more (for example, 300 or more) from the viewpoint of haze reduction effect. A more preferable range of the molecular weight of the surfactant may vary depending on the type of the surfactant. For example, when polyoxyethylene alkyl ether is used as the surfactant, the molecular weight is, for example, preferably less than 2000, more preferably 1900 or less (for example, less than 1800), and even more preferably 1500 or less, and may be 1000 or less (for example, 500 or less). In addition, when a block copolymer of EO and PO is used as the surfactant, the weight average molecular weight may be, for example, 500 or more, 1000 or more, even 1500 or more, 2000 or more, or even 2500 or more. The upper limit of the weight average molecular weight is, for example, less than 5000, preferably 4500 or less, and may be, for example, less than 4000, less than 3800, or less than 3500.

The molecular weight of the surfactant may be the molecular weight calculated from the chemical formula, or the weight average molecular weight determined by GPC (water-based, polyethylene glycol equivalent). The same measurement conditions for GPC can be used as for the water-soluble polymers described above. For example, in the case of polyoxyethylene alkyl ether, it is preferable to use the molecular weight calculated from the chemical formula, and in the case of a block copolymer of EO and PO, it is preferable to use the weight average molecular weight determined by the above GPC.

In an embodiment in which the polishing composition contains a surfactant, the content of the surfactant is usually 20 parts by weight or less, preferably 10 parts by weight or less, and more preferably 6 parts by weight or less (e.g., 3 parts by weight or less) per 100 parts by weight of abrasive grains (typically organic particles) from the viewpoint of cleaning properties, etc. From the viewpoint of better exerting the effect of using the surfactant, the content of the surfactant per 100 parts by weight of abrasive grains is appropriately 0.001 parts by weight or more, preferably 0.01 parts by weight or more, more preferably 0.1 parts by weight or more, and may be 0.5 parts by weight or more.

<Chelating Agent>
The polishing composition disclosed herein may contain a chelating agent. In general, a chelating agent suppresses metal contamination by capturing metal impurity components in the polishing composition to form a complex, thereby contributing to the reduction of defects caused by metal contamination.

Examples of chelating agents include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents. Specific examples of aminocarboxylic acid chelating agents include alanine, glycine, ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid, sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, sodium triethylenetetraminehexaacetate, and trans-1,2-cyclohexanediaminetetraacetic acid. Specific examples of organic phosphonic acid chelating agents include, for example, 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, phosphonobutanetricarboxylic acid (PBTC), nitrilotris(methylenephosphonic acid) (NTMP), and α-methylphosphonosuccinic acid. Among these chelating agents, ethylenediaminetetraacetic acid, diethyltriaminepentaacetic acid, triethylenetetraminehexaacetic acid, ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), and trans-1,2-cyclohexanediaminetetraacetic acid are preferred, and ethylenediaminetetrakis(methylenephosphonic acid), triethylenetetraminehexaacetic acid, and trans-1,2-cyclohexanediaminetetraacetic acid are more preferred. The chelating agents can be used alone or in combination of two or more.

Although not particularly limited, in some embodiments, the content of the chelating agent in the polishing composition can be, for example, 0.01 parts by weight or more per 100 parts by weight of abrasive grains (typically organic particles). From the viewpoint of reducing defects caused by metal contamination, it is appropriate to set it to 0.1 parts by weight or more, preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, and may be 2 parts by weight or more. In addition, the content of the chelating agent per 100 parts by weight of abrasive grains may be, for example, 20 parts by weight or less, or may be 10 parts by weight or less. From the viewpoint of dispersion stability of the polishing composition, etc., in some embodiments, the content of the chelating agent per 100 parts by weight of abrasive grains is appropriate to be 7 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and may be, for example, 2.5 parts by weight or less. By appropriately setting the amount of the chelating agent used within the above range, high surface quality can be obtained.

<Water>
The polishing composition disclosed herein typically contains water. As the water contained in the polishing composition, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc. can be preferably used. In order to avoid as much as possible the inhibition of the action of other components contained in the polishing composition, the water used preferably has a total transition metal ion content of, for example, 100 ppb or less. For example, the purity of the water can be increased by removing impurity ions with an ion exchange resin, removing foreign matter with a filter, distillation, or other operations. In addition, the polishing composition disclosed herein may further contain an organic solvent (lower alcohol, lower ketone, etc.) that can be mixed uniformly with water, if necessary. It is preferable that 90% by volume or more of the solvent contained in the polishing composition is water, and more preferably 95% by volume or more (for example, 99 to 100% by volume) is water.

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

The organic acids and their salts, and 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, and organic sulfonic acids such as itaconic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, glycolic acid, malonic acid, gluconic acid, lactic acid, and methanesulfonic acid. Examples of organic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of organic acids. Examples of inorganic acids include hydrochloric acid, phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, phosphinic acid, boric acid, and carbonic acid. Examples of inorganic acid salts include alkali metal salts (sodium salts, potassium salts, etc.) and ammonium salts of inorganic acids.

The polishing composition disclosed herein is preferably substantially free of oxidizing agents. If an oxidizing agent is contained in the polishing composition, the surface of the substrate (e.g., silicon wafer) may be oxidized by supplying the polishing composition to the substrate, resulting in an oxide film, which may result in a decrease in the polishing rate. Specific examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), sodium persulfate, ammonium persulfate, and sodium dichloroisocyanurate. The polishing composition being substantially free of oxidizing agents means that the oxidizing agent is not intentionally contained at least. Therefore, a polishing composition that inevitably contains a small amount of oxidizing agent (e.g., the molar concentration of the oxidizing agent in the polishing composition is 0.001 mol/L or less, preferably 0.0005 mol/L or less, more preferably 0.0001 mol/L or less, even more preferably 0.00005 mol/L or less, and particularly preferably 0.00001 mol/L or less) due to raw materials, manufacturing method, etc., can be included in the concept of a polishing composition that does not substantially contain an oxidizing agent.

<pH>
The pH of the polishing composition disclosed herein is not particularly limited, and an appropriate pH can be adopted according to the substrate and the like. In some embodiments, the pH of the polishing composition is suitably 8.0 or more, preferably 8.5 or more, more preferably 9.0 or more. When the pH of the polishing composition is high, the polishing rate tends to improve. The pH of the polishing composition is usually suitably 12.0 or less, preferably 11.0 or less, more preferably 10.8 or less, and even more preferably 10.5 or less.

In the technology disclosed herein, the pH of the polishing composition can be determined by using a pH meter (for example, a glass electrode type hydrogen ion concentration indicator (model number F-72) manufactured by Horiba, Ltd.) and performing three-point calibration using standard buffer solutions (phthalate pH buffer, pH: 4.01 (25°C), neutral phosphate pH buffer, pH: 6.86 (25°C), carbonate pH buffer, pH: 10.01 (25°C)), then placing the glass electrode in the composition to be measured and measuring the value after it has stabilized for at least two minutes.

<Polishing solution>
The polishing composition disclosed herein is typically supplied to the surface of a substrate in the form of a polishing liquid containing the polishing composition, and is used to polish the substrate. The polishing liquid can be prepared, for example, by diluting any of the polishing compositions disclosed herein (typically diluting with water). Alternatively, the polishing composition can be used as it is as a polishing liquid. Another example of the polishing liquid containing the polishing composition disclosed herein is a polishing liquid obtained by adjusting the pH of the composition.

The content of abrasive grains (typically organic particles) in the polishing liquid is not particularly limited, and is, for example, 0.005% by weight or more, preferably 0.01% by weight or more, more preferably 0.03% by weight or more, and even more preferably 0.06% by weight or more. By increasing the abrasive grain content, a higher polishing rate can be realized. The content is suitably 10% by weight or less, preferably 7% by weight or less, more preferably 5% by weight or less, and even more preferably 2% by weight or less, and may be, for example, 1% by weight or less, 0.5% by weight or less, or 0.4% by weight or less. This makes it easier to maintain the surface quality.

In some embodiments, the content of the water-soluble polymer in the polishing liquid (the total content of the water-soluble polymers when two or more kinds of water-soluble polymers are included) may be, for example, 0.0001% by weight or more from the viewpoint of improving surface quality, and is usually 0.0005% by weight or more, and is preferably 0.001% by weight or more, and may be, for example, 0.002% by weight or more, or may be 0.0025% by weight or more. The upper limit of the content of the water-soluble polymer is not particularly limited, and may be, for example, 0.05% by weight or less. In some embodiments, the content of the 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 from the viewpoint of stability, polishing rate, cleanability, etc. at the concentrated liquid stage. The polishing liquid disclosed herein may also be implemented in an embodiment in which the content of the water-soluble polymer is, for example, 0.008% by weight or less, 0.006% by weight or less, 0.004% by weight or less, or 0.003% by weight or less.

The content of the basic compound in the polishing liquid is not particularly limited. From the viewpoint of improving the polishing rate, it is usually appropriate that the content is 0.0005% by weight or more, preferably 0.001% by weight or more, and more preferably 0.003% by weight or more. Also, from the viewpoint of improving the surface quality (e.g., reducing haze), it is appropriate that the content is less than 0.1% by weight, preferably less than 0.05% by weight, and more preferably less than 0.03% by weight (e.g., less than 0.025% by weight, or even less than 0.01% by weight).

When a surfactant is included, the content of the surfactant in the polishing liquid (the total content when two or more surfactants are included) is not particularly limited as long as it is within a range that does not significantly impair the effects of the present invention. Usually, the content of the surfactant can be, for example, 0.00001 wt % or more from the viewpoint of cleaning properties, etc. From the viewpoint of haze reduction, etc., the preferred content is 0.0002 wt % or more, more preferably 0.0003 wt % or more, and even more preferably 0.0005 wt % or more. Also, from the viewpoint of polishing rate, etc., the content is preferably 0.1 wt % or less, more preferably 0.01 wt % or less, and even more preferably 0.005 wt % or less (for example, 0.002 wt % or less).

In an embodiment in which the polishing composition contains a chelating agent, the content of the chelating agent in the polishing liquid is not particularly limited. From the viewpoint of improving surface quality, the content of the chelating agent in the polishing liquid may be, for example, 0.0001% by weight or more, and is usually 0.0005% by weight or more, and is preferably 0.001% by weight or more, may be 0.0015% by weight or more, or may be 0.002% by weight or more. The upper limit of the content of the chelating agent is not particularly limited, and may be, for example, 0.1% by weight or less. From the viewpoint of stability at the concentrated liquid stage, polishing rate, cleanability, etc., in some embodiments, the content of the chelating agent is preferably 0.05% by weight or less, more preferably 0.01% by weight or less, even more preferably 0.008% by weight or less, and may be 0.006% by weight or less.

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

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

In some embodiments, the total content of the water-soluble polymer in the concentrated liquid can be, for example, 3% by weight or less. From the viewpoint of the filterability and washability of the polishing composition, the content is usually preferably 1% by weight or less, and more preferably 0.5% by weight or less. Also, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content is usually 0.001% by weight or more, preferably 0.005% by weight or more, and more preferably 0.01% by weight or more.

In some embodiments, the content of the basic compound in the concentrated solution can be, for example, less than 15% by weight. From the viewpoint of storage stability, etc., the content is usually preferably 0.7% by weight or less, and more preferably 0.4% by weight or less. Also, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content of the basic compound in the concentrated solution can be, for example, 0.005% by weight or more, preferably 0.01% by weight or more, more preferably 0.02% by weight or more, and even more preferably 0.05% by weight or more.

In an embodiment in which the polishing composition contains a surfactant, the content of the surfactant in the concentrated liquid can 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 may be 0.025% by weight or less. The content of the surfactant in the concentrated liquid can 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.

In an embodiment in which a chelating agent is included in the polishing composition, the content of the chelating agent in the concentrated liquid can be, for example, 3% by weight or less. From the viewpoint of the filterability and washability of the polishing composition, the content is usually preferably 1% by weight or less, and more preferably 0.5% by weight or less. Furthermore, from the viewpoint of convenience and cost reduction during production, distribution, storage, etc., the content is usually appropriate to be 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more.

<Preparation of Polishing Composition>
The polishing composition used in the technology disclosed herein may be a one-component type or a multi-component type including a two-component type. For example, the polishing composition may be configured to prepare a polishing liquid by mixing a part A containing at least abrasive grains and a part B containing at least a part of the remaining components, and mixing and diluting them at an appropriate timing as necessary.

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

<Applications>
The polishing composition disclosed herein can be applied to polishing a substrate. The material of the substrate can be a silicon material. The shape of the substrate is not particularly limited. The polishing composition disclosed herein can be applied to polishing a substrate having a flat surface, such as a plate-like or polyhedral substrate, or polishing the edge of a substrate (e.g., polishing a wafer edge).

The polishing composition disclosed herein can be used for polishing a surface made of a silicon material (typically, polishing a silicon wafer). Specific examples of silicon materials include silicon single crystal, amorphous silicon, and polysilicon. The polishing composition disclosed herein can be particularly preferably used for polishing a surface made of silicon single crystal (e.g., polishing a silicon wafer).

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

The polishing composition disclosed herein uses organic particles as abrasives, and can improve the surface quality after polishing to a high level. For this reason, the polishing composition disclosed herein is effective when used in the finishing step of a substrate (e.g., a silicon wafer) or in the polishing step immediately preceding it, and use in the finish polishing step is particularly preferred. Here, the finish polishing step refers to the final polishing step in the manufacturing process of the target object (i.e., a step in which no further polishing is performed after that step). The polishing composition disclosed herein may also be used in a polishing step upstream of the finish polishing (a preliminary polishing step between the rough polishing step and the final polishing step, which typically includes at least a primary polishing step and may further include secondary, tertiary, etc. polishing steps), for example, a polishing step performed immediately preceding the finish polishing.

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

<Polishing>
The polishing composition disclosed herein can be used for polishing a substrate, for example, in an embodiment including the following operations. Hereinafter, a preferred embodiment of a method for polishing a silicon wafer as a substrate using the polishing composition disclosed herein will be described.
That is, a polishing liquid containing any one of the polishing compositions disclosed herein is prepared. The preparation of the polishing liquid may include adjusting the concentration (e.g., diluting), adjusting the pH, etc., of the polishing composition to prepare the polishing liquid. Alternatively, the polishing composition may be used as it is as the polishing liquid.

Then, the polishing liquid is supplied to the substrate, and the substrate is polished in a conventional manner. For example, when performing finish polishing of a silicon wafer, typically, the silicon wafer that has undergone the lapping process is set in a general polishing device, and the polishing liquid is supplied to the surface of the silicon wafer to be polished through the polishing pad of the polishing device. Typically, while the polishing liquid is continuously supplied, the polishing pad is pressed against the surface of the silicon wafer to be polished, and the two are moved relative to one another (e.g., rotated). Through this polishing process, the polishing of the substrate is completed.

The polishing pad used in the above polishing process is not particularly limited. For example, polishing pads of polyurethane foam type, nonwoven fabric type, suede type, etc. can be used. Each polishing pad may or may not contain abrasive grains. Usually, polishing pads that do not contain abrasive grains are preferably used.

The substrate polished with the polishing composition disclosed herein is typically cleaned. Cleaning can be performed with an appropriate cleaning solution. The cleaning solution used is not particularly limited, and for example, SC-1 cleaning solution (a mixture of ammonium hydroxide (NH ₄ OH), hydrogen peroxide (H ₂ O ₂ ), and water (H ₂ O)), SC-2 cleaning solution (a mixture of HCl, H ₂ O _{2 ,} and H ₂ O), ozone water cleaning solution, hydrofluoric acid cleaning solution, and the like, which are common in the field of semiconductors, etc., can be used. The temperature of the cleaning solution can be, for example, in the range of room temperature (typically about 15° C. to 25° C.) or higher, up to about 90° C.

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

The matters disclosed in this specification include the following.
[1] A polishing composition used for polishing a surface made of a silicon material, comprising:
The abrasive grains and a water-soluble polymer are included,
The polishing composition, wherein the abrasive grains comprise organic particles.
[2] The polishing composition according to [1] above, wherein the organic particles are one or more kinds of particles selected from acrylic resin, styrene resin, styrene-acrylic resin, polyamide resin, polyimide resin, epoxy resin, polyester resin, polyurethane resin, phenol resin, melamine resin, benzoguanamine resin, polyethersulfone resin and polytetrafluoroethylene resin.
[3] The polishing composition according to the above [1] or [2], wherein the organic particles have an average particle size of less than 5 μm.
[4] The polishing composition according to any one of [1] to [3] above, wherein the abrasive grains further contain inorganic particles.
[5] The polishing composition according to [4] above, wherein the inorganic particles contain colloidal silica.
[6] The polishing composition according to the above [4] or [5], wherein a weight ratio of the content of the inorganic particles to the content of the organic particles is 0.03 or more and 99 or less.
[7] The polishing composition according to any one of [1] to [6] above, wherein the water-soluble polymer comprises a vinyl alcohol-based polymer.
[8] The polishing composition according to any one of [1] to [7] above, wherein the content of the water-soluble polymer is 0.5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the abrasive grains.
[9] The polishing composition according to any one of [1] to [8] above, further comprising a basic compound.
[10] The polishing composition according to any one of [1] to [9] above, further comprising a surfactant.
[11] A concentrated solution of the polishing composition according to any one of [1] to [10] above.
[12] A polishing method comprising polishing a surface of a silicon material with the polishing composition according to any one of [1] to [11] above.

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

<<Test Example 1>>
<Preparation of Polishing Composition>
(Examples 1 to 6)
Abrasive grains, a basic compound, a water-soluble polymer, a surfactant and deionized water were mixed to prepare a concentrated solution of the polishing composition according to each example. As the abrasive grains, organic particles having the material and particle size (average particle size) shown in the "abrasive grains" column in Table 1 were used. As the basic compound, ammonia was used. As the water-soluble polymer, acetalized polyvinyl alcohol (Ac-PVA; acetalization degree 24 mol%) with Mw of about 9700 was used. As the surfactant, polyoxyethylene decyl ether (C10EO5) with 5 moles of ethylene oxide added was used. The obtained concentrated solution of the polishing composition was diluted with deionized water to a volume ratio of 40 times to obtain a polishing composition according to each example with a concentration of abrasive grains of 0.080%, a concentration of basic compound of 0.005%, a concentration of water-soluble polymer of 0.003%, and a concentration of surfactant of 0.0006%.

(Comparative Example 1)
A polishing composition according to this example was prepared in the same manner as in Example 1, except that colloidal silica having an average primary particle size of 25 nm was used as the abrasive grains instead of the organic particles.

Here, the average primary particle size of the colloidal silica in Comparative Example 1 is a particle size (BET particle size) calculated from the specific surface area (BET value) measured by the BET method according to the formula: average primary particle size (nm) = 6000/(true density (g/ ^cm3 ) x BET value ( ^m2 /g)). The specific surface area was measured using a surface area measuring device manufactured by Micromeritics, product name "Flow Sorb II 2300".

(Comparative Example 2)
A polishing composition according to this example was prepared in the same manner as in Example 3, except that no water-soluble polymer was used.

Table 1 shows an overview of the configuration of each example. The particle diameters of the abrasive particles (organic particles) in Examples 1 to 6 and Comparative Example 2 in Table 1 are manufacturer nominal values (catalog values). The abrasive particles used in Example 1 are anionic non-crosslinked acrylic resin particles. The abrasive particles used in Example 2 are anionic non-crosslinked styrene-acrylic resin particles. The abrasive particles used in Example 3 are anionic non-crosslinked acrylic resin particles. The abrasive particles used in Example 4 are cationic non-crosslinked acrylic resin particles. The abrasive particles used in Example 5 are anionic crosslinked acrylic resin particles. The abrasive particles used in Example 6 are anionic crosslinked styrene-acrylic resin particles. The abrasive particles used in Comparative Example 2 are anionic non-crosslinked acrylic resin particles. The organic particles used are in the form of an aqueous dispersion.

[Polishing of silicon wafers]
As a substrate, a commercially available silicon single crystal wafer having a diameter of 300 mm (conductivity type: P type, crystal orientation: <100>, COP (Crystal Originated Particle)-free) that had been subjected to lapping and etching was subjected to a first stage of pre-polishing (hereinafter also referred to as "primary pre-polishing") under the following polishing condition 1, and then a second stage of pre-polishing (hereinafter also referred to as "secondary pre-polishing") under the following polishing condition 2 was prepared. The primary pre-polishing was performed using a polishing solution containing 0.6% abrasive grains (colloidal silica having an average primary particle size of 35 nm) and 0.08% tetramethylammonium hydroxide (TMAH) in deionized water. The secondary pre-polishing was performed using a polishing solution containing 0.08% abrasive grains (colloidal silica having an average primary particle size of 25 nm), 0.005% ammonia, 0.003% acetalized polyvinyl alcohol having a Mw of approximately 9700 (Ac-PVA; degree of acetalization: 24 mol%), and 0.0006% polyoxyethylene decyl ether (C10EO5) having 5 moles of ethylene oxide added in deionized water.

[Polishing condition 1 (first preliminary polishing)]
Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tools Works, model "PNX-332B"
Polishing load: 20 kPa
Rotation speed of the platen: 20 rpm
Head (carrier) rotation speed: 20 rpm
Polishing pad: Nitta DuPont, product name "SUBA400"
Polishing liquid supply rate: 1.0 L/min Polishing liquid temperature: 20° C.
Temperature of cooling water for surface plate: 20°C
Polishing time: 2 minutes

[Polishing condition 2 (secondary pre-polishing)]
Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tools Works, model "PNX-332B"
Polishing load: 16 kPa
Rotation speed of the platen: 52 rpm
Head (carrier) rotation speed: 50 rpm
Polishing pad: Fujibo Ehime product name "POLYPAS275NX"
Polishing liquid supply rate: 1.5 L/min Polishing liquid temperature: 20° C.
Temperature of cooling water for surface plate: 20°C
Polishing time: 2 minutes

The polishing compositions prepared in each example above were used as polishing liquids to finish-polish the silicon wafers after the first and second preliminary polishing under the following polishing condition 3.

[Polishing condition 3 (finish polishing)]
Polishing device: Single-wafer polishing device manufactured by Okamoto Machine Tools Works, model "PNX-332B"
Polishing load: 20 kPa
Rotation speed of the platen: 52 rpm
Head (carrier) rotation speed: 50 rpm
Polishing pad: Fujibo Ehime product name "POLYPAS27NX"
Polishing liquid supply rate: 1.5 L/min Polishing liquid temperature: 20° C.
Temperature of cooling water for surface plate: 20°C
Polishing time: 2 minutes

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

(Haze measurement)
The haze (ppm) of the silicon wafer surface after cleaning was measured in DW2O mode using a wafer inspection device manufactured by KLA Tencor Corporation under the product name "Surfscan SP5". The obtained haze results were converted into relative values with the haze value of Comparative Example 1 taken as 100%. The obtained results are shown in the "Relative Haze Value" column in Table 1. The smaller the haze value, the higher the effect of improving haze and the greater the effect of reducing surface roughness.

(Defect measurement)
The number of defects on the cleaned silicon wafer surface was measured in DCO mode using a wafer inspection device manufactured by KLA Tencor Corporation under the trade name "Surfscan SP5."

As shown in Table 1, in Examples 1 to 6, in which a polishing composition containing organic particles and a water-soluble polymer was used, the haze after polishing was reduced compared to Comparative Example 1, in which a polishing composition containing colloidal silica instead of organic particles was used, and it was confirmed that the surface roughness after polishing was reduced (improved). Also, in Comparative Example 2, in which a polishing composition not containing a water-soluble polymer was used, it was confirmed that the haze reduction effect was lower compared to Example 3, in which a polishing composition using both acrylic resin particles and a water-soluble polymer was used.

<<Test Example 2>>
<Preparation of Polishing Composition>
(Examples 7 and 8)
A concentrated solution of the polishing composition according to Examples 7 and 8 was prepared by mixing organic particles and inorganic particles as abrasive grains, a basic compound, a water-soluble polymer, a surfactant, and deionized water. As the organic particles, organic particles having the material and particle size (average particle size) shown in the "Abrasive grain 1" column in Table 2 were used. As the inorganic particles, colloidal silica with an average primary particle size of 25 nm was used. As the basic compound, ammonia was used. As the water-soluble polymer, acetalized polyvinyl alcohol (Ac-PVA; acetalization degree 24 mol%) with Mw of about 9700 was used. As the surfactant, polyoxyethylene decyl ether (C10EO5) with 5 moles of ethylene oxide added was used. The resulting concentrated polishing composition was diluted 40 times by volume with deionized water to obtain polishing compositions for each example having an organic particle concentration of 0.020%, an inorganic particle concentration of 0.060%, a basic compound concentration of 0.005%, a water-soluble polymer concentration of 0.003%, and a surfactant concentration of 0.0006%.

Here, the particle diameters of the organic particles in Examples 7 and 8 are manufacturer nominal values (catalog values). The average primary particle diameter of the colloidal silica in Examples 7 and 8 is a particle diameter (BET particle diameter) calculated from the specific surface area (BET value) measured in the same manner as in Comparative Example 1 of Test Example 1. The organic particles used in Example 7 are anionic non-crosslinked styrene-acrylic resin particles. The organic particles used in Example 8 are anionic crosslinked styrene-acrylic resin particles. The organic particles used are in the form of an aqueous dispersion.

　The silicon wafers after the first and second preliminary polishing, which were polished in the same manner as in Test Example 1, were finish-polished under the same conditions as in Test Example 1, polishing condition 3, using the polishing compositions of Examples 7 and 8 prepared above as the polishing liquid, and the polished silicon wafers were washed and dried.

(Haze measurement)
The haze (ppm) of the silicon wafer surface after cleaning was measured in DW2O mode using a wafer inspection device manufactured by KLA Tencor Corporation under the product name "Surfscan SP5". The obtained haze results were converted into relative values with the haze value of Comparative Example 1 of Test Example 1 taken as 100%. The obtained results are shown in the "Relative Haze Value" column of Table 2 together with the results of Comparative Example 1. The smaller the haze value, the higher the effect of improving haze and the higher the effect of reducing surface roughness.

(Defect measurement)
The number of defects on the cleaned silicon wafer surface was measured in DCO mode using a wafer inspection device manufactured by KLA Tencor Corporation under the trade name "Surfscan SP5."

As shown in Table 2, in Examples 7 and 8, in which organic and inorganic particles were used in combination as abrasives, the haze after polishing was reduced compared to Comparative Example 1, in which only inorganic particles were used, and it was confirmed that the surface roughness after polishing was reduced (improved). Also, although not shown in the table, it was confirmed that in Examples 7 and 8, in which organic and inorganic particles were used in combination as abrasives, the number of defects was significantly reduced (e.g., approximately 50% or less) compared to each Example of Test Example 1, in which only organic particles were used as abrasives (e.g., Example 6).

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

Claims (11)

A polishing composition used for polishing a surface made of a silicon material, comprising:
The abrasive grains and a water-soluble polymer are included,
The polishing composition, wherein the abrasive grains comprise organic particles. The polishing composition according to claim 1, wherein the organic particles are one or more types of particles selected from acrylic resin, styrene resin, styrene-acrylic resin, polyamide resin, polyimide resin, epoxy resin, polyester resin, polyurethane resin, phenol resin, melamine resin, benzoguanamine resin, polyethersulfone resin, and polytetrafluoroethylene resin. The polishing composition according to claim 1 or 2, wherein the average particle size of the organic particles is less than 5 μm. The polishing composition according to claim 1 or 2, wherein the abrasive grains further contain inorganic particles. The polishing composition according to claim 4, wherein the inorganic particles include colloidal silica. The polishing composition according to claim 1 or 2, wherein the water-soluble polymer contains a vinyl alcohol-based polymer. The polishing composition according to claim 1 or 2, wherein the content of the water-soluble polymer is 0.5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the abrasive grains. The polishing composition according to claim 1 or 2, further comprising a basic compound. The polishing composition according to claim 1 or 2, further comprising a surfactant. A concentrated solution of the polishing composition according to claim 1 or 2. A polishing method comprising polishing a surface made of a silicon material with the polishing composition according to claim 1 or 2.