Method for polishing silicon substrates

Abstract

To provide a silicon substrate polishing method that can achieve both an improvement in polishing rate and reduction in surface roughness (haze) of a silicon substrate.SOLUTION: A silicon substrate polishing method includes a step of supplying a polishing liquid composition which contains silica particles (component A), amino group-containing water-soluble polymer (component B), and nonionic water-soluble polymer (component C), and has a pH of more than 8.5 and not more than 14, and bringing a silicon substrate to be polished into contact with the surface of a polishing pad. The surface zeta potential of the polishing pad in contact with the polishing liquid composition is equal to -30 mV or more and less than 0 mV.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for polishing a silicon substrate and a method for manufacturing a semiconductor substrate. [Background technology]

[0002] Generally, in polishing silicon substrates and the like, it is known that the silicon substrate to be polished is brought into contact with the surface of a polishing pad while a polishing composition containing particles is supplied. Suede pads are used particularly for finish polishing. With this type of polishing pad, the generation of haze due to excessive contact between the polishing pad and the silicon wafer is a problem (see, for example, Patent Document 1). Furthermore, with this type of polishing composition, the generation of surface defects (LPD: Light Point Defects) on the silicon substrate caused by the aggregation of silica particles and the clogging of filters when filtering the polishing composition to remove the aggregates are problems (see, for example, Patent Document 2). Furthermore, polishing compositions containing water-soluble polymer compounds are known for the purpose of improving the removal rate (see, for example, Patent Document 3).

[0003] Patent Document 1 proposes a method of polishing a silicon substrate by supplying a polishing liquid containing a surfactant such as polyoxyethylene octyl ether having an ethylene oxide addition mole number of 6 between a polishing pad and the silicon substrate. Patent Document 2 proposes a polishing composition containing silica particles, a nitrogen-containing basic compound, and a water-soluble polymer in which the ratio of the number of oxygen atoms derived from hydroxyl groups to the number of oxygen atoms derived from polyoxyalkylene is 0.8 to 10. Patent Document 3 proposes a semiconductor polishing composition containing abrasive grains, a basic compound, and two or more water-soluble polymers, the water-soluble polymers including a cationic water-soluble polymer containing a nitrogen-containing group. The examples in this document describe a semiconductor polishing composition containing colloidal silica, ammonia, tetramethylammonium hydroxide, hydroxyethyl cellulose having a weight-average molecular weight of 800,000, and polyethyleneimine. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-179890 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-109423 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-352042 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, with the rise in demand for semiconductors, the demand for improved productivity and surface quality of silicon substrates such as silicon wafers has become increasingly stringent, and there is a demand for polishing methods that can improve the polishing rate and reduce the surface roughness (haze) of silicon substrates. However, Patent Documents 1 and 2 have a problem in that they are insufficient in improving the polishing rate. Patent Document 3 has a problem in that they are insufficient in reducing haze.

[0006] The present disclosure provides a method for polishing a silicon substrate and a method for manufacturing a semiconductor substrate, which can improve the polishing rate and reduce the surface roughness (haze) of the silicon substrate at the same time. [Means for solving the problem]

[0007] In one aspect, the present disclosure relates to a method for polishing a silicon substrate, comprising the steps of supplying a polishing liquid composition containing silica particles (component A), an amino group-containing water-soluble polymer (component B), and a nonionic water-soluble polymer (component C) and having a pH greater than 8.5 and equal to or less than 14, and contacting the silicon substrate to be polished with the surface of a polishing pad to polish it, wherein the polishing pad in contact with the polishing liquid composition has a surface zeta potential of -30 mV or more and less than 0 mV.

[0008] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, including a step of polishing a silicon substrate to be polished using the polishing method of the present disclosure, and a step of cleaning the polished silicon substrate. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a method for polishing a silicon substrate, which can improve the polishing rate while reducing the surface roughness (haze) of the silicon substrate, and a method for manufacturing a semiconductor substrate. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure is based on the finding that by using a polishing liquid composition containing silica particles, an amino group-containing water-soluble polymer, and a nonionic water-soluble polymer and having a pH greater than 8.5 and equal to or less than 14, the surface zeta potential of a polishing pad can be adjusted to a predetermined value, thereby enabling high-speed polishing of silicon substrates and reducing the surface roughness (haze) of the silicon substrates.

[0011] That is, in one aspect, the present disclosure relates to a method for polishing a silicon substrate (hereinafter also referred to as the "polishing method of the present disclosure"), which includes a step of supplying a polishing liquid composition containing silica particles (component A), an amino group-containing water-soluble polymer (component B), and a nonionic water-soluble polymer (component C) and having a pH greater than 8.5 and not greater than 14, and polishing the silicon substrate to be polished by contacting the surface of a polishing pad, wherein the surface zeta potential of the polishing pad in contact with the polishing liquid composition is -30 mV or more and less than 0 mV.

[0012] According to one or more embodiments of the present disclosure, it is possible to achieve both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate.

[0013] Although the details of the mechanism by which the effects of the present disclosure are exerted are not clear, it is presumed as follows. Polishing progresses as abrasive particles become concentrated at the interface where the polishing pad and the substrate contact. Under alkaline polishing conditions with a pH greater than 8.5 and less than 14, the polishing pad has a large negative charge, and it is thought that the electrostatic repulsion between the polishing pad and abrasive particles such as silica particles prevents the abrasive particles from being sufficiently retained on the polishing pad. In this disclosure, the zeta potential of the polishing pad is adjusted to between -30 mV and less than 0 mV using an amino group-containing water-soluble polymer (component B) and a nonionic water-soluble polymer (component C). This suppresses the electrostatic repulsion between the silica particles (component A) and the polishing pad, improving the retention of abrasive particles on the polishing pad. As a result, the silica particles (component A) are uniformly concentrated at the interface between the polishing pad and the substrate to be polished, ensuring nearly uniform contact of the polishing pad with the substrate to be polished. This is believed to improve the polishing rate while improving the haze level. Furthermore, because the abrasive particles are retained on the surface of the polishing pad, the lower the surface roughness of the polishing pad, the higher the polishing rate and the lower the haze level can be expected. However, the present disclosure need not be construed as being limited to these mechanisms.

[0014] [Polishing process] The polishing method of the present disclosure includes a step of supplying a polishing liquid composition (hereinafter also referred to as the "polishing liquid composition of the present disclosure") containing silica particles (component A), an amino group-containing water-soluble polymer (component B), and a nonionic water-soluble polymer (component C) and having a pH greater than 8.5 and not greater than 14, and polishing the silicon substrate by bringing the substrate into contact with the surface of a polishing pad (hereinafter also referred to as the "polishing step of the present disclosure").

[0015] When the polishing process is performed in multiple stages, the polishing process of the present disclosure is preferably performed in the second stage or later, and more preferably in the final polishing process or finish polishing process. In this case, separate polishing machines may be used for each stage to avoid contamination with abrasives or polishing compositions from the previous process. When separate polishing machines are used, it is preferable to clean the silicon substrate to be polished after each polishing process. Furthermore, the polishing composition of the present disclosure can also be used in circulating polishing, in which the used polishing liquid is reused. The polishing machine is not particularly limited, and known polishing machines for substrate polishing can be used.

[0016] The polishing pressure in the polishing step of the present disclosure is preferably 20 g / cm from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate. 2 More preferably, 50 g / cm 2More preferably, 80 g / cm 2 From the viewpoint of polishing speed and surface roughness (haze), it is preferably 500 g / cm 2 or less, more preferably 300 g / cm 2 More preferably 200 g / cm or less 2 In this disclosure, the polishing pressure refers to the pressure of the platen applied to the polishing surface of the silicon substrate during polishing. The polishing pressure can be adjusted by applying air pressure or a weight to at least one of the platen and the substrate.

[0017] The supply rate of the polishing composition of the present disclosure in the polishing step of the present disclosure is set to 1 / cm of the substrate to be polished from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate. 2 The flow rate is preferably 0.05 to 5 mL / min, more preferably 0.1 to 3 mL / min, even more preferably 0.2 to 2 mL / min, and even more preferably 0.3 to 0.1 mL / min.

[0018] In the polishing step of the present disclosure, the temperature of the polishing liquid composition and the surface temperature of the polishing pad are preferably 15°C or higher and preferably 60°C or lower, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate.

[0019] A method for supplying the polishing liquid composition of the present disclosure includes, for example, a method of continuously supplying the composition using a pump or the like. In the present disclosure, "supply" includes supplying the polishing liquid composition to a polishing machine, supplying it between a polishing pad and a substrate to be polished, supplying it to the surface of a polishing pad, and supplying it to the surface of a substrate to be polished. When supplying the polishing liquid composition, in addition to a method of supplying it as a single liquid containing all components, it can also be divided into multiple blending component liquids and supplied as two or more liquids, taking into consideration the stability of the polishing liquid composition, etc. In the latter case, the multiple blending component liquids are mixed, for example, in the supply pipe or on the substrate to be polished, to produce the polishing liquid composition of the present disclosure.

[0020] [Polishing pad] The polishing pad used in the polishing method of the present disclosure is preferably a suede-type polishing pad having a base layer and a surface layer (hereinafter also referred to as a "foamed layer") made of a foamed polyurethane elastomer, with the surface roughness Ra of the surface layer being 15 μm or less, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate.

[0021] In one or more embodiments, the foam layer serving as the surface layer of the polishing pad can be either a closed-cell type or an open-cell type, but open-cell types are preferred from the viewpoint of the discharge of polishing debris. Examples of open-cell type polishing pads include those described in "CMP Technology Basic Examples Lecture Series, Vol. 2, Fundamentals and Examples of Mechanochemical Polishing (CMP) (Polishing Pad Edition), May 27, 1998, Materials, Edited by Global Net Co., Ltd." or "CMP Science, Edited by Masahiro Kashiwagi, Science Forum Co., Ltd., Chapter 4." Here, the term "suede type" refers, in one or more embodiments, to a structure having a base layer and a foam layer with spindle-shaped pores perpendicular to the base layer, as described in JP-A-11-335979.

[0022] In one or more embodiments, the suede-type polishing pad is manufactured by the following method. A solution of polyurethane elastomer dissolved in a solvent such as dimethylformamide (DMF) is applied to a base layer made of polyethylene terephthalate (PET), and the resulting layer is immersed in water or a mixed solution of water and the solvent for the polyurethane elastomer solution to perform wet coagulation. The resulting layer is then washed with water to remove the solvent and dried. This results in a foamed layer having spindle-shaped pores perpendicular to the base layer on the base layer. The surface of the resulting foamed layer is then polished with sandpaper or the like to obtain a suede-type polishing pad having a foamed layer with pores on the surface and spindle-shaped pores perpendicular to the base layer.

[0023] In one or more embodiments, the material for the base layer of the polishing pad may be a nonwoven fabric made of natural or synthetic fibers such as cotton, or a base layer obtained by filling a rubber-like material such as styrene butadiene rubber. From the viewpoint of reducing microwaviness and obtaining a resin film with high hardness, polyethylene terephthalate (PET) film or polyester film is preferred, and PET film is more preferred. In one or more embodiments, the material for the foam layer (surface layer) of the polishing pad may be polyurethane elastomer, polystyrene, polyester, polyvinyl chloride, natural rubber, synthetic rubber, etc., but polyurethane elastomer is preferred from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate.

[0024] From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the compressibility of the foam layer (surface layer) of the polishing pad is preferably 1% or more, more preferably 3% or more, and is preferably 30% or less, more preferably 25% or less, even more preferably 20% or less, still more preferably 15% or less, still more preferably 10% or less, and still more preferably 5% or less. In the present disclosure, the compressibility of the polishing pad can be measured using a compression tester based on the compressibility measurement method described in Japanese Industrial Standards (JIS) L 1096. The compressibility of the polishing pad can be controlled, for example, by the thickness of the foam layer, the pore size on the base layer side of the foam layer, or the material of the base layer.

[0025] The surface roughness Ra of the foam layer (surface layer) of the polishing pad is preferably 15 μm or less, more preferably 10 μm or less, even more preferably 7 μm or less, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, and is preferably 2 μm or more, more preferably 3 μm or more, even more preferably 4 μm or more. In the present disclosure, the surface roughness Ra of the polishing pad can be measured by the method described in the Examples. The surface roughness Ra of the polishing pad can be controlled, for example, by the pore size on the surface side of the foam layer or the roughness of the pad dresser that polishes the surface of the foam layer.

[0026] The average pore diameter of the pores on the surface of the polishing pad is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 80 μm or less, even more preferably 20 μm or more and 60 μm or less, and even more preferably 25 μm or more and 55 μm or less, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate.

[0027] The average pore size of the pores on the surface of the polishing pad can be controlled by adding additives to the polyurethane elastomer raw material, such as pigments such as carbon black, hydrophilic surfactants that promote foaming, or hydrophobic surfactants that stabilize the wet coagulation of the polyurethane elastomer. In the present disclosure, the average pore size can be determined by the following method. First, the polishing pad surface is observed with a scanning electron microscope (preferably 100 to 300 magnifications), and the image is imported into a personal computer (PC). The imported image is then analyzed using image analysis software on the PC, and the average pore diameter can be determined as the average diameter of the circle-equivalent diameters of the pores. For example, WinROOF (Mitani Corporation) can be used as the image analysis software.

[0028] From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the thickness of the polishing pad is preferably 0.7 mm or more and 2.5 mm or less, more preferably 0.8 mm or more and 2.0 mm or less, even more preferably 0.8 mm or more and 1.7 mm or less, and even more preferably 0.9 mm or more and 1.5 mm or less.

[0029] (Surface zeta potential of polishing pad) In this disclosure, unless otherwise specified, the "surface zeta potential of a polishing pad" refers to the zeta potential of the surface of a polishing pad that has come into contact with the polishing liquid composition of the present disclosure. In one or more embodiments, the surface zeta potential of a polishing pad in this disclosure is the surface zeta potential of a polishing pad model microparticle dispersion obtained by mixing pad fine powder (hereinafter also referred to as "polishing pad model microparticles") having an average particle size of 0.3 μm to 1 μm obtained by polishing the surface layer of a polishing pad made of polyurethane elastomer with a diamond dresser with the polishing liquid composition excluding component A. From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the surface zeta potential of the polishing pad is -30 mV or more, preferably -25 mV or more, more preferably -20 mV or more, and even more preferably -15 mV or more, and is less than 0 mV, preferably -2 mV or less, and more preferably -5 mV or less. In one or more embodiments, the polishing pad model fine particles refer to pad fine powder (fine particles) obtained by polishing the surface layer of a polishing pad made of polyurethane elastomer using a diamond dresser or the like. The obtained fine particles are considered to have a substantially uniform particle size distribution, and the particle size of the fine particles can be adjusted by the grit size of the diamond dresser and the polishing load. The particle size of the fine particles can be, for example, 0.3 μm to 1 μm. For example, a CMP pad conditioner or the like can be used as the diamond dresser. In one or more embodiments, the zeta potential of the polishing pad model fine particles is not measured on the surface of the polishing pad. In the present disclosure, the surface zeta potential of the polishing pad can be measured using a zeta potential measuring device based on electrophoretic light scattering. Specifically, it can be measured using the method described in the Examples.

[0030] [Silicon substrate to be polished] In one or more embodiments, the polishing liquid composition of the present disclosure is a polishing composition for silicon substrates, and can be used, for example, in a polishing step of polishing a silicon substrate to be polished in a method for producing a semiconductor substrate, or in a polishing step of polishing a silicon substrate to be polished in a method for polishing a silicon substrate. In one or more embodiments, examples of the silicon substrate to be polished using the polishing liquid composition of the present disclosure include silicon wafers and silicon substrates, and in one or more embodiments, examples of the silicon substrate to be polished include single crystal silicon substrates, polysilicon substrates, substrates having a polysilicon film, SiN substrates, etc. From the viewpoint of exerting the effects of the polishing liquid composition of the present disclosure, the silicon substrate to be polished is preferably a single crystal silicon substrate or a polysilicon substrate, and more preferably a single crystal silicon substrate.

[0031] [Polishing liquid composition] <Silica particles (ingredient A)> The polishing composition of the present disclosure contains silica particles (hereinafter also referred to as "Component A") as an abrasive. Examples of Component A include colloidal silica, fumed silica, pulverized silica, and surface-modified silica thereof. Colloidal silica is preferred from the viewpoint of achieving both improved polishing rate and storage stability, and from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects, and scratches. Component A may be one type or a combination of two or more types.

[0032] From the viewpoint of ease of use, the use form of Component A is preferably a slurry. When Component A contained in the polishing liquid composition of the present disclosure is colloidal silica, from the viewpoint of preventing contamination of silicon substrates with alkali metals, alkaline earth metals, etc., the colloidal silica is preferably obtained from a hydrolyzate of an alkoxysilane. Silica particles obtained from a hydrolyzate of an alkoxysilane can be produced by a conventionally known method.

[0033] From the viewpoint of maintaining the polishing rate, the average primary particle diameter of component A is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more, and from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects, and scratches, the average primary particle diameter of component A is preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less, and even more preferably 30 nm or less. From the same viewpoint, the average primary particle diameter of component A is preferably 10 nm or more and 50 nm or less, more preferably 15 nm or more and 45 nm or less, even more preferably 20 nm or more and 40 nm or less, and preferably 20 nm or more and 30 nm or less. In the present disclosure, the average primary particle diameter of component A is determined by the specific surface area S (m 2 The average primary particle size is calculated using the formula (1 / g). The average primary particle size is a value measured by the method described in the examples.

[0034] From the viewpoint of maintaining the polishing rate, the average secondary particle diameter of component A is preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 40 nm or more, and from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects, and scratches, the average secondary particle diameter of component A is preferably 100 nm or less, more preferably 90 nm or less, even more preferably 80 nm or less, even more preferably 70 nm or less, and even more preferably 60 nm or less. From the same viewpoint, the average secondary particle diameter of component A is preferably 20 nm or more and 100 nm or less, more preferably 30 nm or more and 90 nm or less, even more preferably 30 nm or more and 80 nm or less, even more preferably 30 nm or more and 70 nm or less, and even more preferably 40 nm or more and 60 nm or less. In the present disclosure, the average secondary particle size is a value measured by dynamic light scattering (DLS) method, and is a value measured by the method described in the Examples.

[0035] The degree of association of component A is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less, from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects, and scratches, and is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 1.8 or more, from the viewpoint of improving the polishing rate. In the present disclosure, the degree of association of component A is a coefficient representing the shape of silica particles and is calculated by the following formula. Degree of association = average secondary particle size / average primary particle size

[0036] The degree of association of component A can be adjusted by using methods described in, for example, JP-A Nos. 6-254383, 11-214338, 11-60232, 2005-060217, and 2005-060219.

[0037] The shape of component A is preferably a so-called spherical shape and / or a so-called cocoon shape from the viewpoint of achieving both an improvement in removal rate and storage stability, and from the viewpoint of improving surface quality.

[0038] The content of component A in the polishing liquid composition of the present disclosure is, from the viewpoint of improving the polishing rate, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.07% by mass or more, and even more preferably 0.1% by mass or more, calculated as SiO. From the viewpoint of improving storage stability and surface quality, the content is preferably 2.5% by mass or less, more preferably 1% by mass or less, even more preferably 0.8% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less. From the same viewpoint, the content of Component A in the polishing liquid composition of the present disclosure is preferably 0.01 mass% or more and 2.5 mass% or less, more preferably 0.05 mass% or more and 1 mass% or less, even more preferably 0.07 mass% or more and 0.8 mass% or less, even more preferably 0.07 mass% or more and 0.5 mass% or less, even more preferably 0.07 mass% or more and 0.3 mass% or less, and even more preferably 0.07 mass% or more and 0.2 mass% or less. When Component A is a combination of two or more types, the content of Component A refers to the total content thereof.

[0039] <Amino group-containing water-soluble polymer (ingredient B)> The polishing composition of the present disclosure contains an amino group-containing water-soluble polymer (hereinafter also referred to as "Component B"). In this disclosure, "water-soluble" means that the polymer has a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more.

[0040] In one or more embodiments of the present disclosure, component B is a water-soluble polymer that can adjust the surface zeta potential of the polishing pad to -30 mV or more and less than 0 mV. In one or more embodiments, component B does not contain an amino group-containing water-soluble polymer (for example, polyethyleneimine) that positively charges the surface zeta potential of the polishing pad.

[0041] From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, it is preferable that Component B contains one or more monomer-derived structural units selected from allylamine and diallylamine. From the viewpoint of availability, Component B is preferably an amino group-containing water-soluble polymer containing an allylamine-derived structural unit (hereinafter also referred to as "Component B1"), and in one or more embodiments, it is preferably an amino group-containing water-soluble polymer containing a diallylamine-derived structural unit (hereinafter also referred to as "Component B2").

[0042] (Component B1: Amino group-containing water-soluble polymer containing allylamine-derived structural units) In one or more embodiments, at least a portion of the amino groups in the allylamine-derived structural unit preferably have a sterically shielding group from the viewpoints of both improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate, and from the viewpoint of availability. In the present disclosure, the sterically shielding group refers to a sterically (bulky) substituent that can shield the nitrogen atom of the amino group of Component B to suppress cationization, i.e., lower the pKa. From the same viewpoint, the amino group having the sterically shielding group is preferably a secondary or tertiary amino group containing a hydrocarbon group having 3 to 11 carbon atoms and a hydroxyl group. The number of carbon atoms in the hydrocarbon group is preferably 3 or more from the viewpoints of improving the shielding ability of the amino group (suppressing the cationization of the nitrogen atom of the amino group) and both improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate. From the viewpoints of improving water solubility and availability, the number of carbon atoms is preferably 11 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 4 or less.

[0043] In one or more embodiments, the amino group having a sterically shielding group is a modified group of an amino group by a glycidol derivative, and in one or more embodiments, is a group formed by reaction of an amino group in an allylamine-derived structural unit with a glycidol derivative. At least some of the amino groups of all the amino groups in component B1 are modified with the glycidol derivative to become amino groups having a sterically shielding group. The equivalent of the glycidol derivative relative to the number of amino groups (1 equivalent) in the allylamine-derived structural unit (hereinafter also referred to as the "glycidol modification rate") is, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.8 or more, still more preferably 1 or more, preferably more than 1.1, even more preferably 1.2 or more, even more preferably 1.3 or more, even more preferably 1.4 or more, and still more preferably 1.5 or more; and, from the viewpoint of improving the polishing rate, it is preferably 4 or less, more preferably 3 or less, even more preferably 2.5 or less, even more preferably 2 or less, even more preferably 1.9 or less, and still more preferably 1.6 or less.

[0044] In the present disclosure, the glycidol modification rate is 13 The glycidol modification rate is a value measured by the method described in the Examples using C-NMR. However, the glycidol modification rate can also be measured by the following method (1) or (2). (1) It can be calculated from the amino group equivalent of the allylamine polymer used as the reaction raw material and the number of moles of the glycidol derivative. (2) The nitrogen content N (mass %) of the reaction product of the glycidol derivative and the allylamine polymer is measured, and the nitrogen content N can be calculated from the following formula: Glycidol modification rate = A / B Here, A=(100−N×molecular weight of allylamine monomer / 14) / molecular weight of glycidol derivative, and B=N / 14.

[0045] Examples of the glycidol derivative include glycidol and alkyl glycidyl ether, and glycidol is preferred from the viewpoints of availability and achieving both an improved polishing rate and a reduced surface roughness (haze) of the silicon substrate. The alkyl group of the alkyl glycidyl ether is preferably an alkyl group having 1 to 8 carbon atoms from the viewpoint of availability, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a 2-ethylhexyl group. Examples of the alkyl glycidyl ether include methyl glycidyl ether and 2-ethylhexyl glycidyl ether.

[0046] In one or more embodiments, component B1 includes a polyallylamine in which at least some of the amino groups have a sterically shielding group, and in one or more embodiments, a reaction product of a polyallylamine with a glycidol derivative.

[0047] In one or more embodiments, Component B1 may be a compound containing a structural unit of the following formula (I) (glycidol-modified polyallylamine). [ka]

[0048] In formula (I), R1 and R 2 are each a hydrogen atom or a sterically shielding group. Examples of the sterically shielding group include modifying groups derived from glycidol derivatives, and in one or more embodiments, examples thereof include one-molar adducts or two-molar adducts of glycidol, and in one or more embodiments, examples thereof include -CHCH(OH)CH(OH), -CHCH(OH)CHO-CHCH(OH)CH(OH), etc.

[0049] (Component B2: Amino group-containing water-soluble polymer containing constitutional units derived from diallylamine) In one or more embodiments, at least a portion of the amino groups in the diallylamine-derived structural unit preferably have an electron-withdrawing group at the β- or γ-position of the amino group, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate. Examples of the electron-withdrawing group include a group represented by the following formula (II): [ka]

[0050] In one or more embodiments, component B2 includes a compound containing a constitutional unit derived from diallylamine and a constitutional unit derived from sulfur dioxide, and examples thereof include a compound containing a constitutional unit represented by the following formula (III): [ka]

[0051] In formula (III), R 3 is an alkyl group having 1 to 3 carbon atoms which may have a hydroxyl group. From the viewpoint of availability and economic efficiency, R 3 is preferably a methyl group. Furthermore, n+m=1, and n and m are 0 or 1. From the same viewpoint, a compound where m=1 and n=0 is preferred. Note that a mixture of a compound where m=1 and n=0 and a compound where m=0 and n=1 may also be used.

[0052] In one or more embodiments, Component B2 includes a compound containing a constituent unit represented by the following formula (IV), such as a methyldiallylamine / sulfur dioxide copolymer. [ka]

[0053] From the viewpoint of improving the polishing rate, the weight-average molecular weight of Component B is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and even more preferably 2,000 or more, and from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 12,000 or less. The weight-average molecular weight of Component B in the present disclosure can be measured, for example, by the method described in the Examples.

[0054] When component B is component B1, the weight-average molecular weight of component B is, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, even more preferably 2,000 or more, even more preferably 3,000 or more, even more preferably 5,000 or more, even more preferably 6,000 or more, and even more preferably 7,000 or more, and from the same viewpoint, preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 12,000 or less.

[0055] When component B is component B2, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the weight-average molecular weight of component B is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and still more preferably 2,000 or more, and from the same viewpoint, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 12,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, even more preferably 5,000 or less, and even more preferably 4,000 or less.

[0056] From the viewpoint of achieving both an improvement in the removal rate and a reduction in the surface roughness (haze) of the silicon substrate, the content of Component B in the polishing liquid composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, and even more preferably 0.004% by mass or more, and from the same viewpoint, the content is preferably 0.05% by mass or less, more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less.

[0057] The ratio of the content of component B to the content of component A in the polishing liquid composition of the present disclosure (mass ratio B / A) is preferably 0.01 or more, more preferably 0.02 or more, and even more preferably 0.04 or more, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, and from the same viewpoint, is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.2 or less.

[0058] <Nonionic water-soluble polymer (ingredient C)> In one or more embodiments, the polishing liquid composition of the present disclosure contains a nonionic water-soluble polymer (hereinafter also referred to as "component C") from the viewpoint of simultaneously improving the removal rate and reducing the surface roughness (haze) of the silicon substrate. In one or more embodiments, component C is a nonionic water-soluble polymer that can adjust the surface zeta potential of the polishing pad to be equal to or greater than -30 mV and less than 0 mV. From the same viewpoint, component C is preferably a nonionic water-soluble polymer having an alkylene oxide group, a hydroxyl group, or an amide group in the molecule. Examples of the alkylene oxide group include an ethylene oxide group and a propylene oxide group. Component C may be one type or a combination of two or more types.

[0059] From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, Component C can be at least one selected from polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight-average molecular weight of 300 or more and 1,000 or less. From the viewpoint of simultaneously improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate, and from the viewpoint of suppressing foaming of the polishing liquid, the alkyl group of the polyglycerol alkyl ether preferably has 3 to 22 carbon atoms, more preferably 5 to 16 carbon atoms, and even more preferably 7 to 12 carbon atoms. The alkyl group may be a linear or branched alkyl group. From the viewpoint of improving wettability, the average degree of polymerization of the glycerol units of the polyglycerol alkyl ether is 5 or more, preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. From the viewpoint of simultaneously improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate, it is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less. Examples of the polyglycerol alkyl ether include polyglycerol lauryl ether, polyglycerol decyl ether, and polyglycerol myristyl ether. From the viewpoint of simultaneously improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate, and from the viewpoint of suppressing foaming of the polishing liquid, the alkyl group of the polyglycerol alkyl ester is preferably an alkyl group having 3 to 22 carbon atoms, more preferably an alkyl group having 5 to 16 carbon atoms, and even more preferably an alkyl group having 7 to 12 carbon atoms. The alkyl group may be a linear or branched alkyl group. From the viewpoint of improving wettability, the average degree of polymerization of the glycerol units of the polyglycerol alkyl ester is 5 or more, preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. From the viewpoint of simultaneously improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate, it is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less. Examples of the polyglycerol alkyl ester include polyglycerol lauryl ester, polyglycerol decyl ester, and polyglycerol myristyl ester. From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the hydroxyalkyl cellulose is preferably at least one selected from hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, and hydroxybutyl cellulose, and more preferably hydroxyethyl cellulose (HEC). Among these, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, Component C is preferably at least one selected from polyglycerin, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), hydroxyethyl cellulose (HEC), and polyethylene glycol (PEG) having a weight-average molecular weight of 300 or more and 1,000 or less, more preferably polyglycerin or hydroxyethyl cellulose, and more preferably polyglycerin.

[0060] From the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, the weight-average molecular weight of Component C is preferably 300 or more, preferably 500 or more, preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more. From the same viewpoint and from the viewpoint of the filterability of the polishing liquid, the weight-average molecular weight is preferably less than 500,000, more preferably 400,000 or less, and even more preferably 300,000 or less. When component C is polyglycerol, from the same viewpoint, the weight average molecular weight of component C is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, and even more preferably 6,000 or less. When component C is polyvinyl alcohol (PVA), from the same viewpoint, the weight average molecular weight of component C is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, and is preferably 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less. When component C is polyvinylpyrrolidone (PVP), from the same viewpoint, the weight average molecular weight of component C is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, and is preferably 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less. When component C is hydroxyethyl cellulose (HEC), from the same viewpoint, the weight average molecular weight of component C is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more, and is preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less. When component C is polyethylene glycol (PEG) having a weight-average molecular weight of 300 or more and 1,000 or less, the weight-average molecular weight of component C is preferably 500 or more and 900 or less, more preferably 800 or less, from the same viewpoint. The weight average molecular weight of Component C can be measured by the method described in the Examples below.

[0061] From the viewpoint of simultaneously improving the removal rate and reducing the surface roughness (haze) of the silicon substrate, the content of component C in the polishing liquid composition of the present disclosure is preferably 0.0005% by mass or more, more preferably 0.0020% by mass or more, even more preferably 0.0050% by mass or more, and preferably 0.05% by mass or less, more preferably 0.02% by mass or less, and even more preferably 0.01% by mass or less. From the same viewpoint, the content of component C in the polishing liquid composition of the present disclosure is preferably 0.0005% by mass or more and 0.05% by mass or less, more preferably 0.00020% by mass or more and 0.02% by mass or less, and even more preferably 0.0050% by mass or more and 0.01% by mass or less. When component C is a combination of two or more types, the content of component C refers to the total content thereof.

[0062] In the polishing liquid composition of the present disclosure, the ratio C / A of the content of component C to the content of component A (mass ratio C / A) is preferably 0.001 or more, more preferably 0.005 or more, even more preferably 0.01 or more, even more preferably 0.015 or more, even more preferably 0.02 or more, and preferably 1 or less, more preferably 0.7 or less, even more preferably 0.4 or less, even more preferably 0.2 or less, and even more preferably 0.1 or less, from the viewpoint of simultaneously improving the polishing rate and reducing the surface roughness (haze) of the silicon substrate. From the same viewpoint, the mass ratio C / A in the polishing liquid composition of the present disclosure is preferably 0.015 or more and 0.2 or less, and more preferably 0.02 or more and 0.1 or less.

[0063] <Water> In one or more embodiments, the polishing composition of the present disclosure may contain water. Examples of water include ion-exchanged water and ultrapure water. The content of water in the polishing composition of the present disclosure may be, for example, the remainder of Component A, Component B, Component C, and the optional components described below.

[0064] <Nitrogen-containing basic compound (component D)> In one or more embodiments, the polishing liquid composition of the present disclosure preferably further contains a nitrogen-containing basic compound (hereinafter also referred to as "component D") from the viewpoint of adjusting the pH. In one or more embodiments, component D is a nitrogen-containing basic compound that can adjust the surface zeta potential of the polishing pad to be greater than or equal to -30 mV and less than 0 mV. Component D is preferably a water-soluble nitrogen-containing basic compound from the viewpoint of achieving both an improved removal rate and a reduced surface roughness (haze) of the silicon substrate. In this disclosure, "water-soluble" refers to a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more. In this disclosure, "water-soluble nitrogen-containing basic" refers to a nitrogen-containing compound that exhibits basicity when dissolved in water. In one or more embodiments, component D does not include an amino group-containing water-soluble polymer (component B). Component D may be a single compound or a combination of two or more compounds.

[0065] In one or more embodiments, Component D may be at least one selected from an amine compound and an ammonium compound, such as ammonia, ammonium hydroxide, ammonium carbonate, ammonium hydrogencarbonate, dimethylamine, trimethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-(β-aminoethyl)ethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hexamethylenediamine, piperazine hexahydrate, anhydrous piperazine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, diethylenetriamine, tetramethylammonium hydroxide, and hydroxyamine, or a combination of two or more selected from these. Among these, from the viewpoint of achieving both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the silicon substrate, ammonia or a mixture of ammonia and hydroxyamine is preferred as component D, and ammonia is more preferred.

[0066] When the polishing composition of the present disclosure contains component D, the content of component D in the polishing composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, and even more preferably 0.003% by mass or more, from the viewpoint of achieving both an improvement in the removal rate and stability of the polishing composition. From the viewpoint of suppressing corrosion of the silicon substrate, it is preferably 0.08% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less. From the same viewpoint, the content of component D is preferably 0.001% by mass or more and 0.5% by mass or less, more preferably 0.002% by mass or more and 0.3% by mass or less, and even more preferably 0.003% by mass or more and 0.3% by mass or less. When component D is a combination of two or more types, the content of component D refers to the total content thereof.

[0067] When the polishing liquid composition of the present disclosure contains component D, the ratio D / A of the content of component D to the content of component A in the polishing liquid composition of the present disclosure (mass ratio D / A) is preferably 0.002 or more, more preferably 0.01 or more, even more preferably 0.015 or more, and even more preferably 0.025 or more, from the viewpoint of achieving both an improvement in the removal rate and stability of the polishing liquid composition, and is preferably 1 or less, more preferably 0.5 or less, even more preferably 0.1 or less, and even more preferably 0.08 or less, from the viewpoint of suppressing corrosion of the silicon substrate. From the same viewpoint, the mass ratio D / A in the polishing liquid composition of the present disclosure is preferably 0.002 or more and 1 or less, more preferably 0.01 or more and 0.5 or less, more preferably 0.015 or more and 0.1 or less, and even more preferably 0.025 or more and 0.08 or less.

[0068] <Other ingredients> The polishing liquid composition of the present disclosure may further contain other components to the extent that the effects of the present disclosure are not impaired. In one or more embodiments, the other components include water-soluble polymers other than Component B and Component C, pH adjusters other than Component D, preservatives, alcohols, chelating agents, and oxidizing agents.

[0069] <ph> From the viewpoint of simultaneously improving the removal rate and reducing the surface roughness (haze) of the silicon substrate, the pH of the polishing liquid composition of the present disclosure is greater than 8.5, preferably greater than 9, more preferably greater than 9.5, and even more preferably greater than 10. From the same viewpoint, the pH is less than 14, preferably less than 13, more preferably less than 12.5, even more preferably less than 12, even more preferably less than 11.5, and even more preferably less than 11. From the same viewpoint, the pH of the polishing liquid composition of the present disclosure is greater than 8.5 and less than 14, preferably less than 9, more preferably less than 13, more preferably less than 9, more preferably less than 12.5, even more preferably less than 9, more preferably less than 12, even more preferably less than 9.5, even more preferably less than 11.5, even more preferably less than 10. The pH of the polishing liquid composition of the present disclosure can be adjusted using component D or a known pH adjuster. In the present disclosure, the pH is a value measured by the method described in the Examples.

[0070] The polishing composition of the present disclosure can be produced, for example, by blending components A, B, and C, and, optionally, water, component D, and other components, using a known method. That is, the polishing composition of the present disclosure can be produced, for example, by blending at least components A, B, and C. Therefore, in another aspect, the present disclosure relates to a method for producing a polishing composition, comprising blending at least components A, B, and C. In the present disclosure, "blending" includes mixing components A, B, and C, and, if necessary, water, component D, and other components simultaneously or in any order. The blending can be carried out using, for example, a stirrer such as a homomixer, homogenizer, ultrasonic disperser, wet ball mill, or bead mill. The preferred amounts of each component in the method for producing a polishing composition of the present disclosure can be the same as the preferred contents of each component in the polishing composition of the present disclosure.

[0071] In the present disclosure, the "content of each component in the polishing composition" refers to the content of each component at the time of use, that is, at the time when the polishing composition begins to be used for polishing.

[0072] The polishing liquid composition of the present disclosure may be produced as a concentrate from the viewpoint of storage and transportation, and diluted at the time of use. The dilution ratio is preferably 2 times or more, more preferably 10 times or more, even more preferably 30 times or more, and even more preferably 50 times or more from the viewpoint of production and transportation costs, and is preferably 180 times or less, more preferably 140 times or less, even more preferably 100 times or less, and even more preferably 70 times or less from the viewpoint of storage stability. The polishing liquid composition concentrate of the present disclosure can be used by diluting it with water so that the contents of each component are the above-mentioned contents (i.e., the contents at the time of use) at the time of use. In the present disclosure, the "time of use" of the polishing liquid composition concentrate refers to the diluted state of the polishing liquid composition concentrate.

[0073] [Method of manufacturing semiconductor substrate] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate (hereinafter also referred to as the "semiconductor substrate manufacturing method of the present disclosure"), which includes a step of polishing a silicon substrate to be polished using the polishing method of the present disclosure (hereinafter also referred to as the "polishing step") and a step of cleaning the polished silicon substrate (hereinafter also referred to as the "cleaning step"). According to the semiconductor substrate manufacturing method of the present disclosure, by using the polishing method of the present disclosure, it is possible to achieve both an improvement in the polishing rate and a reduction in surface roughness (haze), thereby enabling high-quality semiconductor substrates to be manufactured at high yield, high productivity, and low cost.

[0074] The polishing step in the semiconductor substrate manufacturing method of the present disclosure can include, for example, a lapping (rough polishing) step of planarizing a single crystal silicon substrate obtained by slicing a single crystal silicon ingot into a thin disk, and a finish polishing step of etching the lapped single crystal silicon substrate and then mirror-finishing the surface of the single crystal silicon substrate. From the viewpoint of achieving both an improvement in the polishing rate and an improvement in the surface quality, the polishing composition of the present disclosure is more preferably used in the finish polishing step.

[0075] The polishing step in the semiconductor substrate manufacturing method of the present disclosure can include, for example, a step of removing irregularities in the polysilicon film to planarize a substrate in which a polysilicon film is formed by chemical vapor deposition (CVD) on a silicon substrate having a silicon dioxide film and a silicon nitride film, and a step of simultaneously polishing and planarizing the silicon dioxide film, silicon nitride film, and polysilicon film directly below.From the viewpoint of achieving both improved polishing rate and improved surface quality, the polishing composition of the present disclosure is more preferably used in the step of removing irregularities in the polysilicon film to planarize the substrate.

[0076] The polishing step in the semiconductor substrate manufacturing method of the present disclosure can be performed under the same conditions as the polishing step in the polishing method of the present disclosure described above.

[0077] In one or more embodiments, the method for manufacturing a semiconductor substrate according to the present disclosure may include a dilution step of diluting the concentrate of the polishing liquid composition according to the present disclosure prior to the polishing step. The diluent may be, for example, water.

[0078] In the cleaning step of the semiconductor substrate manufacturing method of the present disclosure, inorganic cleaning is preferably performed from the viewpoint of reducing residues on the silicon substrate surface. Examples of cleaning agents used in inorganic cleaning include inorganic cleaning agents containing at least one selected from hydrogen peroxide, ammonia, hydrochloric acid, sulfuric acid, hydrofluoric acid, and ozone water.

[0079] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure can further include, after the cleaning step, a step of rinsing the cleaned silicon substrate with water and drying it. [Example]

[0080] Hereinafter, the present disclosure will be described in more detail with reference to examples, but these are merely illustrative examples and the present disclosure is not limited to these examples.

[0081] 1. Preparation of Polishing Composition The silica particles (component A) shown in Table 1, the amino group-containing water-soluble polymer (component B) shown in Table 1, the nonionic water-soluble polymer (component C) shown in Table 1, ammonia (component D), and ultrapure water were mixed with stirring to obtain polishing liquid compositions of Examples 1 to 4 and Comparative Example 1. The content of each component in Table 1 is the content (mass %, active content) of each component at the time of use of the polishing liquid composition. The content of ultrapure water is the remainder excluding components A, B, C, and D. The pH of each polishing liquid composition at 25°C is shown in Table 1.

[0082] The following components A, B, C, and D were used to prepare each polishing composition. (Component A) Colloidal silica [average primary particle size 25 nm, average secondary particle size 49 nm, degree of association 2.0] (ingredient B) Methyldiallylamine-sulfur dioxide copolymer [Nittobo Medical Co., Ltd., weight-average molecular weight 3,000] Glycidol-modified polyallylamine (modification ratio 2.0) [Nittobo Medical Co., Ltd., weight-average molecular weight 11,000] (Component C) Polyglycerin [Daicel "XPW", polymerization degree 40, weight-average molecular weight 2,980] (Component D) Ammonia [28% by mass ammonia water, Kishida Chemical Co., Ltd., special grade reagent]

[0083] 2.Measuring methods for various parameters (1) Measurement of the average primary particle size of silica particles (component A) The average primary particle diameter (nm) of component A is calculated by the BET (nitrogen adsorption) method. 2 / g) was calculated using the following formula. Average primary particle diameter (nm)=2727 / S

[0084] The specific surface area S of component A was measured by the nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device "Flowsorb III2305", manufactured by Shimadzu Corporation) after carrying out the following [pretreatment]. Approximately 0.1 g of the measurement sample was weighed out to four decimal places into a measuring cell, and the sample was dried for 30 minutes in an atmosphere at 110°C immediately before measuring the specific surface area. [Preprocessing] (a) Adjust the pH of the slurry of component A to 2.5±0.1 with an aqueous solution of nitric acid. (b) The slurry of component A adjusted to pH 2.5±0.1 is placed in a petri dish and dried in a hot air dryer at 150°C for 1 hour. (c) After drying, the obtained sample is finely crushed in an agate mortar. (d) The crushed sample is suspended in ion-exchanged water at 40°C and filtered through a membrane filter with a pore size of 1 μm. (e) The residue on the filter is washed five times with 20 g of ion-exchanged water (40°C). (f) The filter with the filtrate attached thereto is placed in a petri dish and dried in an atmosphere of 110°C for 4 hours. (g) The dried filtrate (component A) was taken out, being careful not to mix in any filter debris, and finely crushed in a mortar to obtain a measurement sample.

[0085] (2) Average secondary particle size of silica particles (component A) The average secondary particle diameter (nm) of component A was measured by adding an abrasive to ion-exchanged water so that the concentration of component A was 0.25% by mass, and then placing the resulting aqueous dispersion in a disposable sizing cuvette (a 10 mm polystyrene cell) to a height of 10 mm from the bottom, using dynamic light scattering (apparatus name: Zetasizer Nano ZS, manufactured by Sysmex Corporation).

[0086] (3) Measurement of the weight-average molecular weight of water-soluble polymers (component B and component C) The weight-average molecular weight of the water-soluble polymers (component B, component C) was calculated based on peaks in a chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions. <Amino group-containing water-soluble polymer (ingredient B)> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: α-M + α-M Eluent: 0.15mol / L Na2SO4,1%CH3COOH / water Flow rate: 1.0mL / min Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight <Nonionic water-soluble polymer (ingredient C)> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: GMPWXL + GMPWXL (anion) Eluent: 0.2M phosphate buffer / CH3CN=9 / 1 Flow rate: 0.5mL / min Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight

[0087] (4) Glycidol modification rate The glycidol modification rate is 13 C-NMR was used to determine the <Measurement conditions> Sample: 200 mg of glycidol-modified polyallylamine dissolved in 0.6 mL of heavy water Equipment used: 400MHz 13 C-NMR (Agilent Technologies "Agilent 400-MR DD2") Measurement conditions: 13 C-NMR measurement, pulse interval time 5 seconds, tetramethylsilane as the standard peak (σ: 0.0 ppm) Accumulation count: 5000 times Each peak range used for integration: A: 71.0 to 72.3 ppm (integrated value of the peak of C bonded to the secondary hydroxyl group of glycidol reacted with the amino group) B: 32.0 to 41.0 ppm (integrated value of the peak of the main chain C of allylamine) <Glycidol modification rate> The glycidol modification rate (ratio of glycidol equivalents to amino group equivalents) is calculated using the following formula. Glycidol modification ratio (equivalent ratio) = 2A / B

[0088] (5) Surface zeta potential of the polishing pad <Method for producing model fine particles for polishing pads> A polishing pad was conditioned using a diamond dresser under the following conditions, and pure water was poured and supplied while being discharged from the outlet to obtain a polishing pad model fine particle aqueous dispersion. <Production conditions> Polishing machine: double-sided polishing machine (9B type double-sided polishing machine, manufactured by Speedfam Co., Ltd.), a different polishing machine from the one used in the polishing evaluation test described below Polishing pad: Suede type (foam layer: polyurethane elastomer), thickness 1.45 mm, average pore size 50 μm (manufactured by Filwel) Diamond dresser: A 95mm diameter, 2mm thick disc-shaped substrate with diamond abrasive grains (grain size #600) bonded to both sides (manufactured by A.L.M.T. Corporation) Number of cards: 2 cards for each carrier, total 6 cards Plate rotation speed: 40 rpm Polishing load: 30g / cm 2 Pure water supply amount: 1L / min When the particle size was measured using a particle size distribution / zeta potential measuring device (device name: "Zetasizer Nano ZS", manufactured by Malvern Instruments), the number average particle size of the polishing pad fine particles was found to be 555 mm. <Method for measuring the surface zeta potential of a polishing pad> An aqueous dispersion of polishing pad model microparticles was mixed with an amino group-containing water-soluble polymer (component B) shown in Table 1, a nonionic water-soluble polymer (component C) shown in Table 1, ammonia (component D), and ultrapure water by stirring to prepare a dispersion for zeta potential measurement in which the contents of components B, C, and D were as shown in Table 1 for each example and comparative example, and the content (solid content) of polishing pad model microparticles was 0.05% by mass. The zeta potential of each dispersion was measured at 25°C using a particle size distribution / zeta potential measuring device (device name: "Zetasizer Nano ZS," manufactured by Malvern Instruments), and the measurement results were obtained as the surface zeta potential of the polishing pad.

[0089] (6) Surface roughness of the polishing pad [Method for evaluating the surface roughness of polishing pads] The surface roughness (Ra) of the polishing pad before use was measured using a tactile surface roughness meter (trade name: SURFTEST SJ-210, manufactured by Mitutoyo Corporation). <Measurement conditions> Roughness standard: ISO1997 Measurement speed: 0.5mm / s Cutoff value: 0.8 mm

[0090] (7) pH of the polishing composition The pH of the polishing composition at 25°C was measured using a pH meter (Toa Dempa Kogyo Co., Ltd., HM-30G), and was the value measured 1 minute after the electrode of the pH meter was immersed in the polishing composition.

[0091] 3. Evaluation of the polishing compositions of Examples 1 to 4 and Comparative Example 1 (1) Polishing method etc. Each polishing composition was filtered with a filter (compact cartridge filter "MCP-LX-C10S", manufactured by Advantech Co., Ltd.) immediately before polishing, and the following silicon substrates were subjected to finish polishing and cleaning under the following polishing conditions. <Silicon substrate to be polished> Single-crystal silicon substrate [200 mm diameter silicon single-sided mirror-finished substrate, conductivity type: P, crystal orientation: 100, resistivity: 0.1 Ω·cm or more but less than 100 Ω·cm] The single crystal silicon substrate was previously subjected to rough polishing using a commercially available polishing composition (GLANZOX 1302, manufactured by Fujimi Inc.). After rough polishing, the single crystal silicon substrate was subjected to finish polishing and had a haze (DNN) of 2 to 3 ppm.

[0092] <Finishing polishing conditions> Polishing machine: Single-sided 8-inch polishing machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo) Polishing pad: Suede pad (manufactured by FILWEL, Asker hardness: 66, thickness: 1.45 mm, nap length: 500 μm, average pore size: 50 μm, surface layer material: polyurethane elastomer, surface layer compressibility: 4%) Polishing pressure: 100g / cm 2 Platen rotation speed: 60 rpm Polishing time: 5 minutes Supply rate of polishing liquid composition: 100mL / min (1 cm of substrate to be polished) 2 (0.32 mL / min per minute) Temperature of polishing composition: 23°C Carrier rotation speed: 62 rpm

[0093] <Cleaning method> After the finish polishing, the silicon substrate was subjected to ozone cleaning and dilute hydrofluoric acid cleaning as follows. For the ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle at a flow rate of 1 L / min toward the center of the silicon substrate rotating at 600 rpm for 3 minutes. The ozone water was kept at room temperature during this process. Next, dilute hydrofluoric acid cleaning was performed. For the dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5 mass% ammonium hydrogen fluoride (special grade, Nakarai Tesque, Inc.) was sprayed from a nozzle at a flow rate of 1 L / min toward the center of the silicon substrate rotating at 600 rpm for 6 seconds. Two sets of the above ozone cleaning and dilute hydrofluoric acid cleaning were performed, and finally, spin drying was performed. For spin drying, the silicon substrate was rotated at 1,500 rpm.

[0094] (2) Evaluation of polishing speed The weight of each silicon substrate before and after polishing was measured using a precision balance ("BP-210S" manufactured by Sartorius), and the resulting weight difference was divided by the density, area, and polishing time of the silicon substrate to determine the single-side polishing rate per unit time. Table 1 shows the relative values, with the polishing rate when the polishing composition of Example 1 was used taken as 100. The weight of the silicon substrate after polishing refers to the weight of the silicon substrate after the above-mentioned finish polishing and cleaning.

[0095] (3) Evaluation of surface roughness (haze) The surface roughness (haze) of the silicon substrate was evaluated by measuring DNN haze, which has higher sensitivity than DWO haze. DNN haze is measured using a surface roughness measurement device "Surfscan SP1-DLS" (manufactured by KLA Tencor) in measurement mode [dark field normal incidence, normal detection channel (DNN)]. The results are shown in Table 1. The smaller the DNN haze value, the smoother the surface.

[0096] [Table 1]

[0097] As shown in Table 1, it was found that the polishing compositions of Examples 1 to 4 were able to achieve both an improved removal rate and a reduced surface roughness (haze) of the silicon substrate, compared to the polishing composition of Comparative Example 1. [Industrial Applicability]

[0098] The polishing method of the present disclosure can improve the polishing rate while reducing the surface roughness (haze) of the silicon substrate. Therefore, the polishing method of the present disclosure is useful as a polishing method used in the manufacturing process of various semiconductor substrates, and is particularly useful as a finish polishing method for silicon substrates.< / ph>

Claims

1. The method includes a step of supplying a polishing liquid composition containing silica particles (component A), an amino group-containing water-soluble polymer (component B), and a nonionic water-soluble polymer (component C), the polishing liquid composition having a pH of more than 8.5 and not more than 14, and bringing the silicon substrate to be polished into contact with the surface of a polishing pad to perform polishing; Component B contains structural units derived from one or more monomers selected from allylamine and diallylamine, at least a portion of the amino groups in the allylamine-derived structural unit have a sterically shielding group; at least a portion of the amino groups in the diallylamine-derived structural unit have an electron-withdrawing group at the β-position or γ-position, The method for polishing a silicon substrate, wherein the polishing pad in contact with the polishing composition has a surface zeta potential of -30 mV or more and less than 0 mV.

2. 2. The polishing method according to claim 1, wherein the polishing pad is a suede-type polishing pad having a base layer and a surface layer made of a foamed polyurethane elastomer, and the surface roughness Ra of the surface layer is 15 μm or less.

3. 3. The polishing method according to claim 1, wherein at least a portion of the amino groups in the structural units derived from the allylamine are secondary amino groups or tertiary amino groups containing a hydrocarbon group having 3 to 11 carbon atoms and a hydroxyl group.

4. 4. The polishing method according to claim 1, wherein component B is a reaction product of polyallylamine and a glycidol derivative.

5. 3. The polishing method according to claim 1, wherein component B is a compound containing a structural unit represented by the following formula (III): 【Chemical 1】 In formula (III), R 3 represents an alkyl group having 1 to 3 carbon atoms which may have a hydroxyl group, and n+m=1.

6. 6. The polishing method according to claim 1, wherein component C is a water-soluble polymer having an alkylene oxide group, a hydroxyl group, or an amide group in the molecule.

7. 7. The polishing method according to claim 1, wherein component C is at least one selected from the group consisting of polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight-average molecular weight of 300 or more and 1,000 or less.

8. a step of polishing a silicon substrate to be polished using the polishing method according to any one of claims 1 to 7; and cleaning the polished silicon substrate.

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