Abrasive liquid composition for silicon oxide film

Abstract

To provide a polishing liquid composition for a silicon oxide film, capable of improving the smoothness of a polished substrate surface, while maintaining its polishing speed.SOLUTION: The present disclosure relates to a polishing liquid composition for a silicon oxide film. In one embodiment, this polishing liquid composition contains: cerium oxide particles (component A); a water-soluble anionic polymer (component B); an unsaturated cyclic compound (component C); and an aqueous medium, wherein component B has an aromatic group in the molecule, and the component C has a functional group represented by formula (I) or formula (II) in the cyclic skeleton thereof.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a polishing liquid composition for a silicon oxide film containing cerium oxide particles, a method for manufacturing a semiconductor substrate using the same, and a method for polishing a substrate.

Background Art

[0002] Chemical mechanical polishing (CMP) technology is a technology in which a polishing liquid is supplied to a contact portion between a surface of a substrate to be polished and a polishing pad while the substrate to be polished and the polishing pad are relatively moved in a state where they are in contact with each other, thereby chemically reacting and mechanically removing surface uneven portions of the substrate to be polished to flatten them.

[0003] Currently, in the manufacturing process of semiconductor elements, when performing planarization of an interlayer insulating film, formation of a shallow trench element isolation structure (hereinafter also referred to as "element isolation structure"), formation of plugs and embedded metal wirings, etc., this CMP technology is an essential technology. In recent years, the multilayer and high-definition of semiconductor elements have advanced dramatically, and it is desired to be able to polish at high speed while having better flatness. For example, in the formation process of a shallow trench element isolation structure, improvement in polishing selectivity of a polishing stopper film (for example, a silicon nitride film) with respect to a film to be polished (for example, a silicon oxide film) (in other words, the selectivity of polishing such that the polishing stopper film is less likely to be polished than the film to be polished) and improvement in flatness are desired together with a high polishing rate.

[0004] For example, Patent Document 1 discloses a polishing liquid for chemical mechanical polishing containing ceria particles having an average aspect ratio of 1.5 or more and an anionic polymer such as polyacrylic acid. Nitrogen-containing heteroaromatic compounds, 4-pyrone, etc. are disclosed as optional components in the same document. Patent Document 2 discloses a polishing liquid containing abrasive grains such as ceria and a copolymer having a structural unit derived from a styrene compound and a structural unit derived from at least one selected from acrylic acid and maleic acid.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] WO2019 / 187977 [Patent Document 2] WO2019 / 064524 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] In recent years, in the field of semiconductors, high integration has been progressing, and the complexity and miniaturization of wiring have been required. Therefore, in CMP polishing, it is required to further improve the flatness while ensuring the polishing rate. One of the causes of the deterioration of the flatness of the substrate surface after polishing is considered to be insufficient suppression of the polishing of the concave portions, resulting in dishing.

[0007] Therefore, the present disclosure provides a polishing liquid composition for a silicon oxide film capable of improving the flatness of the substrate surface after polishing while ensuring the polishing rate, a method for manufacturing a semiconductor substrate using the same, and a polishing method. [Means for Solving the Problems]

[0008] In one aspect, the present disclosure contains cerium oxide particles (Component A), a water-soluble anionic polymer (Component B), an unsaturated cyclic compound (Component C), and an aqueous medium. Component B has an aromatic group in the molecule. Component C has a functional group represented by the following formula (I) or formula (II) in the cyclic skeleton, and relates to a polishing liquid composition for a silicon oxide film. [Chemical Formula] In formula (I), Y represents OM 1 or SM 2 and M 1 and M 2 are the same or different and are an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 +) represents a hydrogen atom or a hydrogen atom. In formula (II), M 3 represents an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ) or a hydrogen atom.

[0009] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, including a step of polishing a film to be polished using the polishing liquid composition of the present disclosure.

[0010] In one aspect, the present disclosure relates to a polishing method including a step of polishing a film to be polished using the polishing liquid composition of the present disclosure, wherein the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate.

Advantages of the Invention

[0011] According to the present disclosure, in one aspect, it is possible to provide a polishing liquid composition for a silicon oxide film that can improve the flatness of the substrate surface after polishing while ensuring the polishing rate.

Modes for Carrying Out the Invention

[0012] As a result of intensive studies by the present inventors, based on the finding that by including a specific anionic polymer and a specific unsaturated cyclic compound in a polishing liquid composition using cerium oxide particles as abrasive grains, it is possible to improve the flatness of the substrate surface after polishing while ensuring the polishing rate.

[0013] In one aspect, the present disclosure contains cerium oxide particles (Component A), a water-soluble anionic polymer (Component B), an unsaturated cyclic compound (Component C), and an aqueous medium, relates to a polishing liquid composition for a silicon oxide film (hereinafter, also referred to as "the polishing liquid composition of the present disclosure") in which Component B has an aromatic group in the molecule and Component C has a functional group represented by the above formula (I) or formula (II) in the cyclic skeleton. According to the present disclosure, in one aspect, it is possible to provide a polishing liquid composition for a silicon oxide film that can improve the flatness of the substrate surface after polishing while ensuring the polishing rate.

[0014] Although the details of the mechanism of the effect manifestation of the present disclosure are not clear, it is presumed as follows. In order to suppress dishing while ensuring the polishing rate of the convex portion, it is necessary to suppress the polishing rate for the concave portion without significantly impairing the polishing rate for the convex portion. Component C can be adsorbed on the silicon oxide film or cerium oxide particles by the functional group represented by the above formula (I) or formula (II) in the cyclic skeleton, and can be desorbed when a high stress is applied. That is, Component C can be adsorbed on the silicon oxide film or cerium oxide particles in the concave portion where the load is difficult to be applied to form a protective film, and can be desorbed in the convex portion where a high load is applied, so that it is considered that dishing can be suppressed while ensuring the polishing rate of the convex portion. Component B is considered to improve the strength of the protective film formed by Component C by interacting with Component C through an aromatic ring, suppress the polishing rate for the concave portion, and improve the flatness of the surface of the substrate after polishing. However, the present disclosure may not be construed as being limited to these mechanisms.

[0015] [Cerium oxide particles (Component A)] The polishing liquid composition of the present disclosure contains cerium oxide (hereinafter, also referred to as "ceria") particles (hereinafter, simply referred to as "Component A") as polishing abrasive grains. As Component A, positively charged ceria or negatively charged ceria can be used. The charge property of Component A can be confirmed by measuring the potential (surface potential) on the surface of the abrasive grains, for example, by the electrokinetic sonic amplitude (ESA method). The surface potential can be measured using, for example, a "zeta probe" (manufactured by Kyowa Interface Science Co., Ltd.), and specifically, it can be measured by the method described in the examples. Component A may be of one type or a combination of two or more types.

[0016] The production method, shape, and surface state of Component A may not be particularly limited. Examples of Component A include colloidal ceria, amorphous ceria, and ceria-coated silica. Colloidal ceria can be obtained, for example, by a build-up process using the methods described in Examples 1 to 4 of Japanese Patent Application Laid-Open No. 2010-505735. Examples of amorphous ceria include, for example, pulverized ceria. One embodiment of pulverized ceria is, for example, calcined pulverized ceria obtained by calcining and pulverizing a cerium compound such as cerium carbonate or cerium nitrate. Other embodiments of pulverized ceria include, for example, single crystal pulverized ceria obtained by wet pulverizing ceria particles in the presence of an inorganic acid or an organic acid. Examples of the inorganic acid used during wet pulverization include nitric acid, and examples of the organic acid include organic acids having a carboxyl group, specifically, at least one selected from polycarboxylate salts such as ammonium polyacrylate, picolinic acid, glutamic acid, aspartic acid, aminobenzoic acid, and p-hydroxybenzoic acid. For example, when at least one selected from picolinic acid, glutamic acid, aspartic acid, aminobenzoic acid, and p-hydroxybenzoic acid is used during wet pulverization, positively charged ceria can be obtained, and when a polycarboxylate salt such as ammonium polyacrylate is used during wet pulverization, negatively charged ceria can be obtained. Examples of the wet pulverization method include wet pulverization using a planetary ball mill or the like. Examples of ceria-coated silica include composite particles having a structure in which at least a part of the surface of silica particles is coated with granular ceria, obtained, for example, by the methods described in Examples 1 to 14 of Japanese Patent Application Laid-Open No. 2015-63451 or Examples 1 to 4 of Japanese Patent Application Laid-Open No. 2013-119131, and the composite particles can be obtained, for example, by depositing ceria on silica particles.

[0017] Examples of the shape of Component A include substantially spherical, polyhedral, and raspberry-like.

[0018] From the perspective of improving the polishing rate, the average primary particle size of Component A is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 20 nm or more, and even more preferably 30 nm or more. From the perspective of suppressing the occurrence of polishing scratches, it is preferably 300 nm or less, more preferably 200 nm or less, still more preferably 150 nm or less, even more preferably 100 nm or less, even more preferably 80 nm or less, and even more preferably 60 nm or less. In the present disclosure, the average primary particle size of Component A is calculated using the BET (nitrogen adsorption) specific surface area S (m 2 / g) calculated by the BET method. The BET specific surface area can be measured by the method described in the examples.

[0019] From the perspectives of improving the polishing rate and flatness, the content of Component A in the polishing liquid composition of the present disclosure is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. From the perspective of suppressing the occurrence of polishing scratches, it is preferably 6% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and even more preferably 0.7% by mass or less. More specifically, the content of Component A is preferably 0.001% by mass or more and 6% by mass or less, more preferably 0.01% by mass or more and 6% by mass or less, still more preferably 0.05% by mass or more and 3% by mass or less, even more preferably 0.1% by mass or more and 1% by mass or less, and even more preferably 0.15% by mass or more and 0.7% by 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.

[0020] [Water-soluble anionic polymer (Component B)] The polishing liquid composition of the present disclosure contains a water-soluble anionic polymer (hereinafter, also simply referred to as "Component B"). Component B is a water-soluble anionic polymer having an aromatic group in the molecule. In one or more embodiments, from the viewpoint of improving the polishing rate and flatness, the aromatic group is preferably a group containing an aromatic ring. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and the like. In one or more embodiments, Component B is considered to be able to suppress the dishing rate during over-polishing while ensuring the polishing rate of the silicon oxide film, and can improve the flatness of the substrate surface after polishing. Note that dishing refers to a dish-shaped depression caused by excessive polishing of the concave portion. In the present disclosure, "water-soluble" means dissolving in the polishing liquid composition of the present disclosure, and preferably having a solubility of 0.5 g / 100 mL or more, more preferably 2 g / 100 mL or more, with respect to water (20 °C). Component B may be one kind or a combination of two or more kinds.

[0021] In one or more embodiments, from the viewpoint of improving the polishing rate and flatness, Component B includes a water-soluble anionic condensate (hereinafter, "Component B1" and "Component B2") having a benzene ring or a naphthalene ring in the main chain, and a copolymer (hereinafter, "Component B3") including a structural unit derived from styrene and a structural unit derived from a monomer having an anionic group.

[0022] <Component B1: Water-soluble anionic condensate> In one or more embodiments, Component B1 is a water-soluble anionic condensate having a benzene ring in the main chain. In one or more embodiments, Component B1 is a co-condensate of monomers including a monomer represented by the following formula (III) (hereinafter, also referred to as "structural monomer b11") and a monomer represented by the following formula (IV) (hereinafter, also referred to as "structural monomer b12"). Component B1 may be one kind or a combination of two or more kinds.

[0023] (Structural monomer b11) The structural monomer b11 is a monomer represented by the following formula (III). [Chemical formula]

[0024] In formula (III), R 1 and R 2 are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or -OM 5 . R 1 and R 2 are, in one or more embodiments, preferably at least one of them is -OM 5 from the viewpoint of polymerization reactivity, and more preferably -OH. R 1 and R 2 are, in one or more embodiments, preferably at least one of them is a hydrogen atom from the viewpoints of improving polishing rate and flatness. M 4 and M 5 are the same or different and each represents an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ), or a hydrogen atom. Examples of the organic cation include organic ammonium in one or more embodiments, such as alkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium. M 4 is, in one or more embodiments, preferably at least one selected from alkali metal ions, ammonium (NH 4 + ), and hydrogen atoms from the viewpoints of improving polishing rate and flatness, and more preferably at least one selected from sodium ions, potassium ions, ammonium (NH 4 + ), and hydrogen atoms. M 5 is, in one or more embodiments, preferably at least one selected from alkali metal ions, ammonium (NH 4 + ), and hydrogen atoms from the viewpoints of improving polishing rate and flatness, and more preferably at least one selected from sodium ions, potassium ions, ammonium (NH 4 +At least one selected from a hydrogen atom is more preferable, and a hydrogen atom is even more preferable.

[0025] As the constituent monomer b11, in one or more embodiments, from the viewpoints of improving polishing rate and flatness, hydroxybenzoic acid (HBA) and dihydroxybenzoic acid (DHBA) are preferable, 4-hydroxybenzoic acid (4-HBA), 2-hydroxybenzoic acid (2-HBA), 2,4-dihydroxybenzoic acid (2,4-HBA), and 2,6-dihydroxybenzoic acid (2,6-HBA) are more preferable, and 4-hydroxybenzoic acid (4-HBA) is even more preferable.

[0026] (Constituent monomer b12) The constituent monomer b12 is a monomer represented by the following formula (IV).

Chemical formula

[0027] In formula (IV), R 3 and R 4 are the same or different and represent a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or -OM 6 . R 3 and R 4 are, in one or more embodiments, preferably at least one of them is -OM 6 from the viewpoints of improving polishing rate and flatness, and more preferably -OH. R 3 and R 4 are, in one or more embodiments, preferably at least one of them is a hydrogen atom from the viewpoints of improving polishing rate and flatness. X 1 represents -SO 3 M 7 or -PO 3 M 8 M 9 . X 1 is preferably -SO 3 M 7 from the viewpoint of dissolution stability in one or more embodiments. M 6 , M7 , M 8 and M 9 are the same or different and represent an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ), or a hydrogen atom. As the organic cation, in one or more embodiments, organic ammonium may be mentioned, for example, alkylammonium such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, etc. M 6 , in one or more embodiments, from the viewpoint of improving polishing rate and flatness, at least one selected from alkali metal ions, ammonium (NH 4 + ), and hydrogen atoms is preferable, and at least one selected from sodium ions, potassium ions, ammonium (NH 4 + ) and hydrogen atoms is more preferable. M 7 , M 8 and M 9 are the same or different and, in one or more embodiments, from the viewpoint of improving polishing rate and flatness, at least one selected from alkali metal ions, ammonium (NH 4 + ), and hydrogen atoms is preferable, and at least one selected from sodium ions, potassium ions, ammonium (NH 4 + ) and hydrogen atoms is more preferable.

[0028] As the constituent monomer b12, in one or more embodiments, phenolsulfonic acid (PhS) may be mentioned.

[0029] The molar ratio (%) of the constituent monomer b11 to the total of the constituent monomers b11 and b12 in Component B1 is preferably more than 30%, more preferably 35% or more, still more preferably 40% or more, even more preferably more than 40%, even more preferably 42% or more, even more preferably 43% or more, even more preferably 44% or more, even more preferably 45% or more, even more preferably 46% or more, even more preferably 48% or more, from the viewpoints of improving the polishing rate and flatness.

[0030] In one or more embodiments, Component B1 is preferably an anionic condensate containing a structure represented by the following formula (V) from the viewpoints of improving the polishing rate and flatness.

Chemical formula

[0031] In formula (V), R 5 and R 6 are the same or different and represent a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or -OM 11 . R 5 and R 6 are preferably a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, more preferably a hydrogen atom, in one or more embodiments, from the viewpoints of improving the polishing rate and flatness. M 10 and M 11 are the same or different and represent an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ), or a hydrogen atom. Examples of the organic cation include organic ammonium in one or more embodiments, such as alkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium. M 10 is preferably an alkali metal ion or ammonium (NH 4 +At least one selected from sodium ion, potassium ion, ammonium (NH 4 + ) and hydrogen atom is preferred, and at least one selected from sodium ion, potassium ion, ammonium (NH M 11 is, in one or more embodiments, from the viewpoint of improving polishing rate and flatness, at least one selected from alkali metal ions, ammonium (NH 4 + ) and hydrogen atom is preferred, and at least one selected from sodium ion, potassium ion, ammonium (NH 4 + ) and hydrogen atom is more preferred, and hydrogen atom is even more preferred. In formula (V), X 2 represents -SO 3 M 12 or -PO 3 M 13 M 14 . X 2 is, in one or more embodiments, from the viewpoint of dissolution stability, -SO 3 M 12 is preferred. M 12 M 13 and M 14 are the same or different and represent alkali metal ions, alkaline earth metal ions, organic cations, ammonium (NH 4 + ) or hydrogen atom. Examples of the organic cation include, in one or more embodiments, organic ammonium, such as alkylammonium such as tetramethylammonium, tetraethylammonium, tetrabutylammonium, etc. In formula (V), m and n are mole fractions when m + n = 1. In one or more embodiments, from the perspective of improving polishing rate and flatness, m is preferably greater than 0.3, more preferably 0.35 or more, still more preferably 0.4 or more, even more preferably greater than 0.4, even more preferably 0.42 or more, even more preferably 0.43 or more, even more preferably 0.44 or more, even more preferably 0.45 or more, even more preferably 0.46 or more, and even more preferably 0.48 or more. In one or more embodiments, m is 0.8 or less, 0.75 or less, 0.7 or less, or 0.65 or less.

[0032] Examples of component B1 include co - condensates of 4 - hydroxybenzoic acid (4 - HBA) and phenolsulfonic acid (PhS).

[0033] Component B1 can be produced, for example, by polymerizing a monomer having constituent monomer b11 and constituent monomer b12 by known means such as the addition - condensation method in the presence of formaldehyde. From the perspective of improving hydrolysis resistance and storage stability in the acidic polishing liquid, it is preferably produced by the addition - condensation method.

[0034] In the present disclosure, as the content (mol%) of a certain constituent unit in all constituent units constituting component B1, depending on the synthesis conditions, the amount (mol%) of the compound for introducing the constituent unit charged into the reaction tank in all the constituent units charged into the reaction tank in all steps of the synthesis of component B1 may be used. Also, in the present disclosure, when component B1 contains two or more types of constituent units, as the composition ratio (molar ratio) of the two constituent units, depending on the synthesis conditions, the compound amount ratio (molar ratio) of the compounds for introducing the two constituent units charged into the reaction tank in all steps of the synthesis of component B1 may be used.

[0035] Component B1 may have a constituent unit derived from constituent monomer b11 and a constituent unit derived from constituent monomer b12, or other constituent units not included in the structure represented by formula (III).

[0036] The arrangement of each constituent unit constituting Component B1 may be random, block, or graft.

[0037] <Component B2: Water-soluble anionic condensate> In one or more embodiments, Component B2 is a water-soluble anionic condensate having a benzene ring or a naphthalene ring in the main chain. In one or more embodiments, Component B2 is an anionic condensate containing a constituent unit having an anionic group in the benzene ring or naphthalene ring of the main chain (hereinafter, also simply referred to as "anionic constituent unit"). The anionic group in the anionic constituent unit is, in one or more embodiments, -SO 3 M 12 or -PO 3 M 13 M 14 where M 12 M 13 and M 14 are the same or different and are an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ) or a hydrogen atom. From the viewpoints of ensuring water solubility, suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, the anionic constituent unit preferably has a structure in which at least one hydrogen atom of the benzene ring or naphthalene ring constituting the main chain is substituted with a sulfonic acid group. Examples of the aromatic monomer from which the anionic constituent unit is derived include at least one selected from phenolsulfonic acid, naphthalenesulfonic acid, and salts thereof. Component B2 may be one kind or a combination of two or more kinds. In one or more embodiments, Component B1 is not included in Component B2. Component B1 and Component B2 may be used in combination.

[0038] Component B2 can further contain structural units other than anionic structural units. As the structural units other than anionic structural units, in one or more embodiments, from the viewpoint of ensuring the polishing rate of the silicon oxide film and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, the structural unit b21 represented by the following formula (VI) (hereinafter, also simply referred to as "structural unit b21"), and at least one structural unit selected from the structural unit b22 represented by the following formula (VII) (hereinafter, also simply referred to as "structural unit b22") can be mentioned.

[0039] (Structural unit b21) The structural unit b21 is a structural unit represented by the following formula (VI). [Chemical formula]

[0040] In formula (VI), R 7 and R 8 are the same or different and represent a hydrogen atom or -OM 15 , M 15 represents at least one selected from an alkali metal, an alkaline earth metal, an organic cation, ammonium, and a hydrogen atom, R 9 and R 10 are the same or different and represent a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, or -OM 16 , M 16 is at least one selected from an alkali metal, an alkaline earth metal, an organic cation, ammonium, and a hydrogen atom, X 3 is a bond, -CH 2 -, -S-, -SO 2 -, -C(CH 3 ) 2 -, or [Chemical formula] is. In formula (VI), R 7 and R 8 are preferably -OH from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing. R9 and R 10 From the viewpoint of ensuring the polishing rate, a hydrogen atom or an alkyl group is preferable, and a hydrogen atom is more preferable. X 3 From the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, -SO 2 - is preferable.

[0041] Examples of the monomer that forms the structural unit b21 include bis(4-hydroxyphenyl)sulfone (BisS), bis(4-hydroxy-3-methylphenyl)sulfone (BSDM), and the like.

[0042] (Structural unit b22) The structural unit b22 is a structural unit represented by the following formula (VII). [Chemical formula]

[0043] In formula (VII), R 11 represents a hydrogen atom or -OM 17 , M 17 is at least one selected from an alkali metal, an alkaline earth metal, an organic cation, ammonium, and a hydrogen atom, and R 12 represents a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, or -OM 18 , M 18 is at least one selected from an alkali metal, an alkaline earth metal, an organic cation, ammonium, and a hydrogen atom. In formula (VII), R 11 is preferably -OH from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing. R 12 is preferably a hydrogen atom or an alkyl group from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing.

[0044] Examples of the monomer that forms the structural unit b22 include p-cresol, phenol, and the like.

[0045] As Component B2, from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, condensates of aromatic monomers having an aromatic ring and an anionic group, condensates containing an anionic constitutional unit and a constitutional unit other than the anionic constitutional unit, and salts thereof can be mentioned. Examples of the salts include alkali metal ions such as sodium salts, ammonium salts, and organic amine salts. As the condensate or its salt of an aromatic monomer having an aromatic ring and an anionic group, from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, a condensate having a structure in which at least one hydrogen atom of the aromatic ring constituting the main chain is substituted with a sulfonic acid group or its salt is preferable, and at least one selected from phenolsulfonic acid, naphthalenesulfonic acid, and their salts is more preferable. As the condensate or its salt containing an anionic constitutional unit and a constitutional unit other than the anionic constitutional unit, from the viewpoints of ensuring the polishing rate and suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing, at least one condensate selected from at least one constitutional unit selected from an anionic constitutional unit, constitutional unit b21, and constitutional unit b22, and at least one selected from their salts is preferable. Examples of Component B2 include at least one selected from condensates of phenolsulfonic acid, condensates of naphthalenesulfonic acid, condensates of bis(4-hydroxyphenyl)sulfone (BisS) and phenolsulfonic acid, condensates of p-cresol and phenolsulfonic acid, condensates of bis(4-hydroxy-3-methylphenyl)sulfone (BSDM) and phenolsulfonic acid, and condensates of phenol and phenolsulfonic acid.

[0046] When component B2 is a condensate containing an anionic structural unit and at least one structural unit selected from structural unit b21 and structural unit b22, the molar ratio of the anionic structural unit to structural unit b21 or structural unit b22 in all the structural units of component B2 (anionic structural unit / structural unit b21, or anionic structural unit / structural unit b22) is preferably from 100 / 0 to 50 / 50, more preferably from 99 / 1 to 60 / 40, and still more preferably from 98 / 2 to 70 / 30, from the viewpoints of suppressing the polishing rate and dishing rate of the silicon nitride film during over-polishing and water solubility.

[0047] Component B2 may further have other structural units other than the anionic structural unit, structural units b21 and b22. Examples of the other structural units include benzenesulfonic acid, halogenated derivatives of benzenesulfonic acid, alkylbenzenesulfonic acid, halogenated derivatives of naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, toluenesulfonic acid, benzoic acid, and the like.

[0048] <Component B3: Copolymer> In one or more embodiments, component B3 is a copolymer containing a structural unit derived from styrene and a structural unit derived from a monomer having an anionic group. From the viewpoints of improving the polishing rate and flatness, component B3 is preferably a copolymer containing a structural unit derived from styrene (hereinafter also referred to as "structural unit b31") and a structural unit derived from at least one monomer selected from acrylic acid (AAc), methacrylic acid, maleic acid (MA), and salts thereof (hereinafter also referred to as "structural unit b32"). Examples of the salts include alkali metal salts, alkaline earth metal salts, ammonium salts, organic ammonium salts, and the like. Component B3 may be one kind or a combination of two or more kinds.

[0049] Examples of component B3 include at least one selected from styrene / acrylic acid copolymer (St / AAc) and styrene / maleic acid copolymer (St / MA).

[0050] The content (mol%) of the structural unit b31 in all the structural units of component B3 is preferably 3 or more, more preferably 5 or more, still more preferably 8 or more from the viewpoint of suppressing dishing, and preferably 80 or less, more preferably 70 or less, still more preferably 50 or less from the viewpoint of water solubility.

[0051] Component B3 may further contain other structural units in addition to the structural units b31 and b32. Examples of the other structural units include vinyl phosphoric acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and the like.

[0052] Component B3 can be obtained, for example, by a known method such as polymerizing a monomer mixture containing styrene and at least one monomer selected from acrylic acid, methacrylic acid, maleic acid, and their salts by solution polymerization. Examples of the solvent used in solution polymerization include water; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and diethylene glycol dimethyl ether; and the like. As the polymerization initiator used in the polymerization, a known radical initiator can be used, and examples thereof include ammonium persulfate salts. During the polymerization, a chain transfer agent can be further used, and examples thereof include thiol-based chain transfer agents such as 2-mercaptoethanol and β-mercaptopropionic acid. In the present disclosure, the content of each structural unit in all the structural units of component B3 can be regarded as the ratio of the usage amount of each monomer to the total amount of the monomers used in the polymerization.

[0053] The arrangement of each structural unit constituting component B3 may be random, block, or graft.

[0054] From the perspective of dishing suppression, the weight-average molecular weight of Component B is preferably 1,500 or more, more preferably 4,000 or more, still more preferably 9,000 or more. From the perspective of polishing rate, it is preferably 100,000 or less, more preferably 80,000 or less, still more preferably 50,000 or less. More specifically, the weight-average molecular weight of Component B is preferably from 1,500 to 100,000, more preferably from 4,000 to 80,000, still more preferably from 9,000 to 50,000. In the present disclosure, the weight-average molecular weight is the value measured under the conditions described in the examples using gel permeation chromatography (GPC). When Component B is Component B1, from the perspective of dishing suppression, the weight-average molecular weight of Component B1 is preferably 1,500 or more, more preferably 5,000 or more, still more preferably 9,000 or more. From the perspective of polishing rate, it is preferably 100,000 or less, more preferably 80,000 or less, still more preferably 50,000 or less. More specifically, the weight-average molecular weight of Component B1 is preferably from 1,500 to 100,000, more preferably from 4,000 to 80,000, still more preferably from 9,000 to 50,000. When Component B is Component B2, from the perspective of dishing suppression, the weight-average molecular weight of Component B2 is preferably 1,500 or more, more preferably 2,000 or more, still more preferably 4,000 or more. From the perspective of polishing rate, it is preferably 50,000 or less, more preferably 40,000 or less, still more preferably 20,000 or less. More specifically, the weight-average molecular weight of Component B2 is preferably from 1,500 to 50,000, more preferably from 2,000 to 40,000, still more preferably from 4,000 to 20,000. When Component B is Component B3, from the perspective of dishing suppression, the weight-average molecular weight of Component B3 is preferably 1,500 or more, more preferably 2,000 or more, still more preferably 3,000 or more. From the perspective of polishing rate, it is preferably 100,000 or less, more preferably 50,000 or less, still more preferably 30,000 or less. More specifically, the weight-average molecular weight of Component B3 is preferably from 1,500 to 100,000, more preferably from 2,000 to 50,000, still more preferably from 3,000 to 30,000.

[0055] From the perspective of suppressing dishing, the content of component B in the polishing liquid composition of the present disclosure is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.02% by mass or more, and from the perspective of polishing rate, it is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, still more preferably 0.1% by mass or less. More specifically, the content of component B is more preferably 0.005% by mass or more and 0.5% by mass or less, still more preferably 0.01% by mass or more and 0.3% by mass or less, and still more preferably 0.02% by mass or more and 0.1% by mass or less. When component B is a combination of two or more, the content of component B refers to their total content.

[0056] From the perspective of improving polishing rate and flatness, the mass ratio B / A of the content of component B to the content of component A in the polishing liquid composition of the present disclosure is preferably 0.01 or more, more preferably 0.03 or more, still more preferably 0.05 or more, and from the same perspective, it is preferably 0.5 or less, more preferably 0.3 or less, still more preferably 0.2. More specifically, the mass ratio B / A is preferably 0.01 or more and 0.5 or less, more preferably 0.03 or more and 0.3 or less, preferably 0.05 or more and 0.2 or less.

[0057] [Unsaturated cyclic compound (component C)] The polishing liquid composition of the present disclosure contains an unsaturated cyclic compound (hereinafter also simply referred to as "component C"). Component C is an unsaturated cyclic compound having a functional group represented by the following formula (I) or formula (II) in the cyclic skeleton. Component C may be one type or a combination of two or more types.

[0058] Examples of the unsaturated ring contained in the unsaturated cyclic compound include unsaturated heterocycles. From the perspective of improving polishing rate and flatness, it is preferable to have at least one nitrogen atom or oxygen atom in the heterocycle.

[0059] (Unsaturated cyclic compound having a functional group represented by formula (I) in the cyclic skeleton) In one or more embodiments, component C is an unsaturated cyclic compound having a functional group represented by the following formula (I) in the cyclic skeleton. [Chemical formula] In formula (I), Y represents OM 1 or SM 2 and M 1 and M 2 are the same or different and represent an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ) or a hydrogen atom. Note that component C can also be referred to as an unsaturated cyclic compound having a functional group represented by the following formula (I´) in the cyclic skeleton from the viewpoint of tautomerism. [Chemical formula]

[0060] As the unsaturated cyclic compound having a functional group represented by formula (I) in the cyclic skeleton, in one or more embodiments, from the viewpoints of improving polishing rate and flatness, an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton having a hydroxyl group at the ortho position of the N-oxide group and its salts (hereinafter also referred to as "component C1"), an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton having a thiol group at the ortho position of the N-oxide group and its salts (hereinafter referred to as "component C2"), etc. may be mentioned.

[0061] In the present disclosure, the N-oxide compound refers to, in one or more embodiments, a compound having an N-oxide group (N→O group). The N-oxide compound can have one or two or more N→O groups, and from the viewpoint of availability, the number of N→O groups is preferably one.

[0062] <N-oxide compound (component C1)> Component C1 is, in one or more embodiments, an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton having a hydroxyl group at the ortho position of the N-oxide group and its salts. Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts, ammonium salts, etc. Component C1 may be used alone or in a combination of two or more.

[0063] In the present disclosure, at least one nitrogen atom contained in the nitrogen-containing heteroaromatic ring skeleton of component C1 forms an N-oxide. As the nitrogen-containing heteroaromatic ring contained in component C1, in one or more embodiments, a monocyclic or bicyclic condensed ring may be mentioned. The number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in component C1 is, in one or more embodiments, 1 to 3, and from the viewpoint of improving the polishing rate, 1 or 2 is preferable, and 1 is more preferable. As the nitrogen-containing heteroaromatic ring skeleton contained in component C1, in one or more embodiments, at least one selected from a pyridine N-oxide skeleton, a quinoline N-oxide skeleton, etc. may be mentioned. In the present disclosure, the pyridine N-oxide skeleton refers to a structure in which the nitrogen atom contained in the pyridine ring forms an N-oxide. The quinoline N-oxide skeleton refers to a structure in which the nitrogen atom contained in the quinoline ring forms an N-oxide.

[0064] As component C1, in one or more embodiments, an N-oxide compound containing a pyridine ring having a hydroxy group at the ortho position of the N-oxide group of the pyridine ring, an N-oxide compound containing a quinoline ring having a hydroxy group at the ortho position of the N-oxide group of the quinoline ring, and at least one selected from salts thereof may be mentioned. Among these, from the viewpoints of improving the polishing rate and water solubility, as component C1, an N-oxide compound containing a pyridine ring having a hydroxy group at the ortho position of the N-oxide group of the pyridine ring or a salt thereof is preferable.

[0065] Examples of component C1 include at least one selected from 2-hydroxypyridine N-oxide and salts thereof.

[0066] <N-oxide compound (component C2)> Component C2 is, in one or more embodiments, an N-oxide compound or a salt thereof that includes a nitrogen-containing heteroaromatic ring skeleton having a thiol group at the ortho position of the N-oxide group of the nitrogen-containing heteroaromatic ring skeleton. Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts, ammonium salts, and the like. Component C2 may be used alone or in combination of two or more.

[0067] In the present disclosure, at least one nitrogen atom contained in the nitrogen-containing heteroaromatic ring skeleton of Component C2 forms an N-oxide. Examples of the nitrogen-containing heteroaromatic ring contained in Component C2 include monocyclic or bicyclic condensed rings in one or more embodiments. The number of nitrogen atoms in the nitrogen-containing heteroaromatic ring contained in Component C2 is, in one or more embodiments, 1 to 3, preferably 1 or 2, and more preferably 1, from the viewpoint of improving the polishing rate. Examples of the nitrogen-containing heteroaromatic ring skeleton contained in Component C2 include at least one selected from a pyridine N-oxide skeleton, a quinoline N-oxide skeleton, and the like in one or more embodiments. In the present disclosure, the pyridine N-oxide skeleton refers to a structure in which the nitrogen atom contained in the pyridine ring forms an N-oxide. The quinoline N-oxide skeleton refers to a structure in which the nitrogen atom contained in the quinoline ring forms an N-oxide.

[0068] Examples of Component C2 include, in one or more embodiments, an N-oxide compound containing a pyridine ring having a thiol group (-SH) at the ortho position of the N-oxide group of the pyridine ring, an N-oxide compound containing a quinoline ring having a thiol group (-SH) at the ortho position of the N-oxide group of the quinoline ring, and at least one selected from salts thereof. Among these, from the viewpoint of improving the polishing rate, Component B2 is preferably an N-oxide compound containing a pyridine ring having a thiol group (-SH) at the ortho position of the N-oxide group of the pyridine ring or a salt thereof.

[0069] Examples of Component C2 include 2-mercaptopyridine N-oxide or a salt thereof.

[0070] (An unsaturated cyclic compound having a functional group represented by formula (II) in a cyclic skeleton) Component C is, in one or more embodiments, an unsaturated cyclic compound having a functional group represented by the following formula (II) in a cyclic skeleton.

Chemical formula

[0071] Examples of the unsaturated cyclic compound having a functional group represented by formula (II) in a cyclic skeleton include, in one or more embodiments, a compound containing an oxygen-containing heterocyclic skeleton having a keto group and a hydroxyl group at the ortho position of the keto group, or a salt thereof (hereinafter also referred to as "Component C3"), from the viewpoints of improving polishing rate and flatness. Examples of the above salts include alkali metal salts, alkaline earth metal salts, organic amine salts such as ethanolamine salts, ammonium salts, and the like. Component C3 may be used alone or in combination of two or more.

[0072] Examples of the oxygen-containing heterocyclic ring contained in Component C3 include, in one or more embodiments, a monocyclic or bicyclic condensed ring. From the viewpoint of improving polishing rate, the number of oxygen atoms in the oxygen-containing heterocyclic ring contained in Component C3 is preferably 1 in one or more embodiments. Examples of the oxygen-containing heterocyclic skeleton contained in Component C3 include, in one or more embodiments, a pyran skeleton.

[0073] Examples of Component C3 include maltol, ethyl maltol, and the like.

[0074] In one or more embodiments, from the perspective of dishing suppression, the content of component C in the polishing liquid composition of the present disclosure is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more, still more preferably 0.0015% by mass or more, and from the perspective of polishing rate, it is preferably 0.1% by mass or less, more preferably 0.04% by mass or less, still more preferably 0.015% by mass or less. More specifically, the content of component C is preferably 0.0001% by mass or more and 0.1% by mass or less, more preferably 0.001% by mass or more and 0.04% by mass or less, still more preferably 0.0015% by mass or more and 0.015% by mass or less. When component C is a combination of two or more types, the content of component C refers to their total content.

[0075] In one or more embodiments, from the perspective of polishing rate, the mass ratio B / C of the content of component B to the content of component C in the polishing liquid composition of the present disclosure is preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, still more preferably 5 or more, still more preferably 8 or more, and from the perspective of dishing suppression, it is preferably 100 or less, more preferably 50 or less, still more preferably 30 or less, still more preferably 25 or less. More specifically, the mass ratio B / C is preferably 1 or more and 100 or less, more preferably 2 or more and 100 or less, still more preferably 3 or more and 50 or less, still more preferably 5 or more and 30 or less, still more preferably 8 or more and 25 or less.

[0076] [Aqueous medium] Examples of the aqueous medium contained in the polishing liquid composition of the present disclosure include water such as distilled water, ion-exchanged water, pure water, and ultrapure water, or a mixed solvent of water and a solvent. Examples of the solvent include solvents miscible with water (for example, alcohols such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the proportion of water in the entire mixed medium may not be particularly limited as long as the effects of the present disclosure are not hindered. From the viewpoint of economy, for example, 95% by mass or more is preferable, and 98% by mass or more is more preferable. From the viewpoint of the surface cleanliness of the substrate to be polished, water is preferable as the aqueous medium, ion-exchanged water and ultrapure water are more preferable, and ultrapure water is even more preferable. The content of the aqueous medium in the polishing liquid composition of the present disclosure can be the remainder excluding component A, component B, component C, and optional components described later that are blended as necessary.

[0077] [Other Components] The polishing liquid composition of the present disclosure can further contain other components such as a pH adjuster, polymers other than component B, surfactants, thickeners, dispersants, rust inhibitors, preservatives, and basic substances.

[0078] [Polishing Liquid Composition] The polishing liquid composition of the present disclosure can be produced, for example, by a production method including a step of blending component A, component B, component C, an aqueous medium, and, if desired, the above-described optional components (other components) by a known method. For example, the polishing liquid composition of the present disclosure can be made by blending at least component A, component B, component C, and an aqueous medium. In the present disclosure, "blending" includes mixing component A, component B, component C, an aqueous medium, and, if necessary, the above-described optional components (other components) simultaneously or in order. The order of mixing is not particularly limited. The blending can be performed, for example, using a mixer such as a homomixer, homogenizer, ultrasonic disperser, and wet ball mill. The blending amounts of the respective components in the production method of the polishing liquid composition of the present disclosure can be the same as the contents of the respective components in the polishing liquid composition of the present disclosure described above.

[0079] Embodiments of the polishing liquid composition of the present disclosure may be in a so-called single-liquid type in which all components are pre-mixed and supplied to the market, or may be in a so-called two-liquid type in which they are mixed during use. For example, as a two-liquid type polishing liquid composition, in one or more embodiments, it is composed of a first liquid containing component A and a second liquid containing component B and component C, and the first liquid and the second liquid are mixed during use. The mixing of the first liquid and the second liquid may be performed before being supplied to the surface of the object to be polished, or they may be supplied separately and mixed on the surface of the substrate to be polished. The first liquid and the second liquid can each contain the optional components described above as required.

[0080] From the viewpoint of improving the polishing rate, the pH of the polishing liquid composition of the present disclosure is preferably 3.5 or more, more preferably 4 or more, still more preferably 5 or more, and from the viewpoint of suppressing dishing, it is preferably 9 or less, more preferably 8.5 or less, still more preferably 8 or less. More specifically, the pH is preferably 3.5 or more and 9 or less, more preferably 4 or more and 8.5 or less, still more preferably 5 or more and 8 or less. In the present disclosure, the pH of the polishing liquid composition is the value at 25°C and can be measured using a pH meter, specifically, it can be measured by the method described in the examples.

[0081] In the present disclosure, "the content of each component in the polishing liquid composition" refers to the content of each component at the time when the use of the polishing liquid composition for polishing is started. The polishing liquid composition of the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. In this case, it is preferable in terms of being able to reduce the manufacturing and transportation costs. And this concentrated liquid can be appropriately diluted with the aforementioned aqueous medium as required and used in the polishing process. The dilution ratio is preferably 5 to 100 times.

[0082] [Film to be polished] Examples of the film to be polished using the polishing liquid composition of the present disclosure include, for example, a silicon oxide film formed in the manufacturing process of a semiconductor substrate. Therefore, the polishing liquid composition of the present disclosure can be used in a process that requires polishing of a silicon oxide film. In one or more embodiments, the polishing liquid composition of the present disclosure is used for polishing a silicon oxide film performed in a process of forming an element isolation structure of a semiconductor substrate, polishing a silicon oxide film performed in a process of forming an interlayer insulating film, polishing a silicon oxide film performed in a process of forming an embedded metal wiring, or polishing a silicon oxide film performed in a process of forming an embedded capacitor. In one or more other embodiments, the polishing liquid composition of the present disclosure can be preferably used in the manufacture of three-dimensional semiconductor devices such as three-dimensional NAND flash memories.

[0083] [Polishing liquid kit] In one aspect, the present disclosure relates to a kit for preparing the polishing liquid composition of the present disclosure (hereinafter, also referred to as "the polishing liquid kit of the present disclosure"). Examples of the polishing liquid kit of the present disclosure include, for example, an abrasive grain dispersion liquid (first liquid) containing component A and an aqueous medium, and an additive aqueous solution (second liquid) containing component B and component C, which are included in a state where they are not mixed with each other, and these are mixed at the time of use and diluted with an aqueous medium as necessary. A polishing liquid kit (two-component type polishing liquid composition) is mentioned. The aqueous medium contained in the abrasive grain dispersion liquid (first liquid) may be the entire amount or a part of the aqueous medium used for preparing the polishing liquid composition. The additive aqueous solution (second liquid) may contain a part of the aqueous medium used for preparing the polishing liquid composition. The abrasive grain dispersion liquid (first liquid) and the additive aqueous solution (second liquid) may each contain the above-described optional components (other components) as necessary. The mixing of the abrasive grain dispersion liquid (first liquid) and the additive aqueous solution (second liquid) may be performed before being supplied to the surface of the object to be polished, or these may be supplied separately and mixed on the surface of the substrate to be polished. According to the polishing liquid kit of the present disclosure, it is possible to obtain a polishing liquid composition capable of improving the flatness of the surface of the substrate after polishing while ensuring the polishing rate of the silicon oxide film.

[0084] [Polishing method] In one aspect, the present disclosure relates to a polishing method (hereinafter also referred to as the polishing method of the present disclosure) that includes a step of polishing a film to be polished using the polishing liquid composition of the present disclosure, where the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate. By using the polishing method of the present disclosure, while ensuring the polishing rate of the silicon oxide film, it is possible to improve the flatness of the surface of the substrate after polishing, so that the productivity of a semiconductor substrate with improved quality can be improved. Specific polishing methods and conditions can be the same as those of the method for manufacturing a semiconductor substrate of the present disclosure described below.

[0085] [Method for manufacturing a semiconductor substrate] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate (hereinafter also referred to as the method for manufacturing a semiconductor substrate of the present disclosure) that includes a step of polishing a film to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as "the polishing step using the polishing liquid composition of the present disclosure"). The method for manufacturing a semiconductor substrate of the present disclosure relates to a method for manufacturing a semiconductor device that includes, for example, a step of polishing the opposite surface of the silicon oxide film that contacts the silicon nitride film, for example, the uneven step surface of the silicon oxide film, using the polishing liquid composition of the present disclosure. According to the method for manufacturing a semiconductor device of the present disclosure, while ensuring the polishing rate of the silicon oxide film, it is possible to improve the flatness of the surface of the substrate after polishing, so that the effect of efficiently manufacturing a semiconductor device can be achieved.

[0086] The uneven step surface of the silicon oxide film may be, for example, naturally formed corresponding to the uneven steps of the underlying layer of the silicon oxide film when the silicon oxide film is formed by a method such as chemical vapor deposition, or may be obtained by forming an uneven pattern using a lithography method or the like.

[0087] As a specific example of the method for manufacturing a semiconductor substrate of the present disclosure, first, a silicon substrate is exposed to oxygen in an oxidation furnace to grow a silicon dioxide layer on its surface, and then silicon nitride (Si 3 N 4)A polishing stopper film such as a film or a polysilicon film is formed by, for example, a CVD method (chemical vapor deposition method). Next, a substrate including a silicon substrate and a polishing stopper film disposed on one main surface side of the silicon substrate, for example, a substrate having a polishing stopper film formed on a silicon dioxide layer of a silicon substrate, is used to form a trench using photolithography technology. Next, for example, by a CVD method using silane gas and oxygen gas, a silicon oxide (SiO 2 ) film, which is a film to be polished for trench filling, is formed to obtain a substrate to be polished in which the polishing stopper film is covered with the film to be polished (silicon oxide film). By forming the silicon oxide film, the trench is filled with silicon oxide of the silicon oxide film, and the opposite surface of the surface of the polishing stopper film on the silicon substrate side is covered with the silicon oxide film. The opposite surface of the surface of the silicon oxide film formed in this way has a step formed corresponding to the unevenness of the lower layer. Next, by the CMP method, the silicon oxide film is polished until at least the opposite surface of the surface of the polishing stopper film on the silicon substrate side is exposed, and more preferably, the silicon oxide film is polished until the surface of the silicon oxide film and the surface of the polishing stopper film are flush. The polishing liquid composition of the present disclosure can be used in the step of performing polishing by this CMP method. The width of the convex portion formed corresponding to the unevenness of the lower layer of the silicon oxide film is, for example, 0.5 μm or more and 5000 μm or less, and the width of the concave portion is, for example, 0.5 μm or more and 5000 μm or less.

[0088] In polishing by the CMP method, with the surface of the substrate to be polished and the polishing pad in contact, the polishing liquid composition of the present disclosure is supplied to these contact portions while the substrate to be polished and the polishing pad are relatively moved, whereby the uneven portions on the surface of the substrate to be polished can be planarized. In the method for manufacturing a semiconductor substrate of the present disclosure, another insulating film may be formed between the silicon dioxide layer of the silicon substrate and the polishing stopper film, or another insulating film may be formed between the film to be polished (for example, a silicon oxide film) and the polishing stopper film (for example, a silicon nitride film, a polysilicon film).

[0089] In the polishing process using the polishing liquid composition of the present disclosure, the rotation speed of the polishing pad is, for example, 30 to 200 rpm / min, the rotation speed of the substrate to be polished is, for example, 30 to 200 rpm / min, and the polishing load set on the polishing apparatus equipped with the polishing pad is, for example, 20 to 500 g / cm 2 , and the supply rate of the polishing liquid composition can be set to, for example, 10 to 500 mL / min or less.

[0090] In the polishing process using the polishing liquid composition of the present disclosure, for the material of the polishing pad used, etc., those conventionally known can be used. Examples of the material of the polishing pad include organic polymer foams such as rigid polyurethane foam and non-foams, etc. Among them, rigid polyurethane foam is preferable.

Examples

[0091] Hereinafter, the present disclosure will be specifically described by way of examples, but the present disclosure is not limited by these examples at all.

[0092] 1. Preparation of polishing liquid composition (Examples 1 to 8, Comparative Examples 1 to 7) Cerium oxide particles (Component A), an anionic polymer shown in Table 1 (Component B or non-Component B), an unsaturated cyclic compound shown in Table 2 (Component C), and water were mixed to obtain the polishing liquid compositions of Examples 1 to 8 and Comparative Examples 1 to 7. The content (mass%) of each component in the polishing liquid composition is as shown in Table 3, and the content of water is the remainder excluding Component A, Component B or non-Component B, and Component C. pH adjustment was carried out using ammonia or nitric acid.

[0093] Cerium oxide particles (Component A) Ground ceria [average primary particle size: 49.5 nm, BET specific surface area 16.8 m 2 / g, surface potential: -50 mV]

[0094] Water-soluble anionic polymer (Component B or non-Component B) The details of the water-soluble anionic polymers shown in Table 1 are shown below. Among the water-soluble anionic polymers shown in Table 1, the formaldehyde (co)condensate is synthesized by dropping formalin at 85 to 105°C over 3 to 6 hours so that the amount of formaldehyde is 0.93 to 0.99 moles per 1 mole of the total amount of monomers, and then performing a condensation reaction at 95 to 105°C for 4 to 9 hours after the dropping. The ratio of the constituent monomers in the copolymer was adjusted by the blending amount (molar ratio) of the monomers. It was visually confirmed that all of the following water-soluble anionic polymers were completely dissolved in the polishing liquid composition. (Component B1) HBA / PhS [Formaldehyde condensate of 4-hydroxybenzoic acid (4-HBA) and p-phenolsulfonic acid (pPhS), constituent monomer molar ratio HBA / PhS = 50 / 50, weight average molecular weight 21,000] (Component B2) BisS / PhS [Formaldehyde condensate of bis(4-hydroxyphenyl)sulfone and phenolsulfonic acid, constituent monomer molar ratio BisS / PhS = 2.5 / 97.5, weight average molecular weight 5,000] Naphthalene sulfone condensate [Formaldehyde condensate of naphthalene sulfonic acid, weight average molecular weight 8,000] (Component B3) St / MA [Styrene / maleic acid copolymer, constituent monomer molar ratio St / MA = 50 / 50, weight average molecular weight 5,000] St / AAc [Styrene / acrylic acid copolymer, constituent monomer molar ratio St / AAc = 10 / 90, weight average molecular weight 15,000] (Non-component B) Polyacrylic acid [Weight average molecular weight 24,000, manufactured by Kao Corporation]

Table 1

[0095] Unsaturated cyclic compound (Component C) (Component C1) HOPO [2-Hydroxypyridine N-oxide, manufactured by Tokyo Chemical Industry Co., Ltd.] (Component C3) Ethyl Maltol [manufactured by Tokyo Chemical Industry Co., Ltd.]

Table 2

[0096] 2. Measurement methods for each parameter (1) pH of the polishing liquid composition The pH value of the polishing liquid composition at 25°C is the value measured using a pH meter (manufactured by Toa DKK Corporation, "HW-41K"), and is the value after 1 minute of immersing the electrode of the pH meter into the polishing liquid composition.

[0097] (2) Average primary particle size of cerium oxide particles (ceria, component A) The average primary particle size (nm) of cerium oxide particles (component A) is obtained by using the specific surface area S (m 2 / g) obtained by the following BET (nitrogen adsorption) method, and calculating with the true density of cerium oxide particles being 7.2 g / cm 3 .

[0098] (3) BET specific surface area of cerium oxide particles (component A) The specific surface area was obtained by heat-drying the cerium oxide particle dispersion at 120°C for 3 hours, then finely pulverizing it in an agate mortar to obtain a sample. After drying for 15 minutes in an atmosphere of 120°C immediately before measurement, it was measured by the nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritics automatic specific surface area measuring device "FlowSorb III 2305", manufactured by Shimadzu Corporation).

[0099] (4) Surface potential of cerium oxide particles (component A) The surface potential (mV) of cerium oxide particles was measured using a surface potential measuring device ("Zeta Probe" manufactured by Kyowa Interface Science Co., Ltd.). Using ultrapure water, the cerium oxide concentration was adjusted to 0.15%, and it was put into the surface potential measuring device, and the surface potential was measured under the conditions of particle density 7.13 g / ml and particle dielectric constant 7. The measurement was performed 3 times, and the average value of them was taken as the measurement result.

[0100] (5) Weight-average molecular weight of the water-soluble anionic polymer (Component B and non-Component B) The weight-average molecular weights of Component B and non-Component B were measured under the following conditions by gel permeation chromatography (GPC) method. <Measurement conditions> Column: G4000SWXL + G2000SWXL (Tosoh) Eluent: 30 mM CH 3 COONa / CH 3 CN = 6 / 4 Flow rate: 0.7 ml / min Detection: UV280 nm Sample size: 0.2 mg / ml Standard substance: Sodium polystyrene sulfonate conversion manufactured by Nishi-ogi Kogyo Co., Ltd. (Monodisperse sodium polystyrene sulfonate: molecular weights, 206, 1,800, 4,000, 8,000, 18,000, 35,000, 88,000, 780,000) Detector: Tosoh Corporation UV-8020

[0101] 3. Dishing evaluation of the polishing liquid composition (Examples 1 to 8, Comparative Examples 1 to 7) (1) Test piece (Blank substrate) By forming a silicon oxide film (blanket film) with a thickness of 2,000 nm on one side of a silicon wafer by the TEOS-plasma CVD method, a silicon oxide film test piece (blanket substrate) was obtained. (Pattern substrate) As an evaluation pattern substrate, a commercially available wafer for CMP characteristics evaluation ("P-TEOS MIT864 PT wafer" manufactured by Advantec, diameter 300 mm) was used. In this evaluation pattern substrate, a silicon nitride film with a thickness of 150 nm is arranged as the first layer and a silicon oxide film with a thickness of 450 nm is arranged as the convex part in the second layer. Similarly, a silicon oxide film with a thickness of 450 nm is arranged in the concave part, and a linear uneven pattern is formed by etching so that the step difference between the convex part and the concave part is 350 nm. The silicon oxide film is formed by P-TEOS, and those with a line width of 100 μm for both the convex part and the concave part were used as the measurement targets.

[0102] (2) Polishing rate of the silicon oxide film on the convex part Using each polishing liquid composition, the above test piece was polished under the following polishing conditions. After polishing, it was washed with ultrapure water and dried, and the test piece was made into a measurement target by the optical interference film thickness measuring device described later. <Polishing conditions> Polishing apparatus: Single-sided polishing machine [manufactured by Ebara Corporation, F REX-200] Polishing pad: Hard urethane pad "IC-1000 / Suba400" [manufactured by Nitta Haas Co., Ltd.] Platen rotation speed: 100 rpm Head rotation speed: 107 rpm Polishing load: 300 g / cm 2 Polishing liquid supply rate: 200 mL / min Polishing time: 1 minute Before and after polishing, using ASET F5x (manufactured by KLA-Tencor Corporation), the film thickness of the silicon oxide film on the convex part was measured. The polishing rate of the silicon oxide film on the convex part was calculated by the following formula. The calculation results are shown in Table 3. Polishing rate of the convex part (nm / min) = [Thickness of the silicon oxide film on the convex part before polishing (nm) - Thickness of the silicon oxide film on the convex part after polishing (nm)] / Polishing time (min)

[0103] (3) Dish amount during over-polishing After the silicon oxide film on the convex part was planarized and the silicon nitride film was exposed, polishing was performed excessively for 20% of the time required for the silicon oxide film on the convex part to be planarized (planarization time). The film thickness of the silicon oxide film in the concave part before and after over-polishing was measured using ASET F5x (manufactured by KLA-Tencor Corporation). The dish amount during over-polishing was calculated by the following formula. Polishing amount of the concave part after the nitride film is exposed (nm) = Height of the convex part when the nitride film is exposed (nm) - Height of the concave part at the end of polishing (nm) The above results are shown in Table 3.

[0104]

Table 3

[0105] As shown in Table 3, in Examples 1 to 8, compared with Comparative Examples 1, 2, 5 to 7 that do not contain Component C, Comparative Example 3 that does not contain Component B and Component C, and Comparative Example 4 that does not contain Component B, while ensuring the polishing rate of the silicon oxide film of the convex portion, the dishing amount of the silicon nitride film during over-polishing decreased and the flatness improved.

Industrial Applicability

[0106] In one or more embodiments, the polishing liquid composition of the present disclosure is useful in a method for manufacturing a semiconductor substrate for high density or high integration.

Claims

1. A polishing liquid composition for a silicon oxide film, comprising cerium oxide particles (Component A), a water-soluble anionic polymer (Component B), an unsaturated cyclic compound (Component C), and an aqueous medium, wherein Component B is an anionic condensate having an aromatic group in the molecule and containing a structure represented by the following formula (V), and Component C has a functional group represented by the following formula (I) or formula (II) in the cyclic skeleton. 【Chemical 1】 In formula (I), Y is OM 1 or SM 2 wherein M 1 and M 2 are the same or different and represent an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ), or a hydrogen atom. In formula (II), M 3 represents an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH 4 + ), or a hydrogen atom. 【Chemical 2】 In formula (V), R5 and R6 are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or -OM11; X2 represents -SO3M12 or -PO3M13M14; M10, M11, M12, M13, and M14 are the same or different and each represents an alkali metal ion, an alkaline earth metal ion, an organic cation, ammonium (NH4+), or a hydrogen atom; m and n are mole fractions when m + n = 1, and m exceeds 0.

3.

2. The polishing liquid composition according to Claim 1, wherein Component C is an N-oxide compound containing a nitrogen-containing heteroaromatic ring skeleton having a hydroxyl group at the ortho position of the N-oxide group and a salt thereof.

3. The polishing liquid composition according to Claim 1, wherein the mass ratio B / C of the content of Component B to the content of Component C is 3 or more.

4. A method for manufacturing a semiconductor substrate, comprising a step of polishing a film to be polished using the polishing liquid composition according to any one of Claims 1 to 3.

5. A polishing method, comprising a step of polishing a film to be polished using the polishing liquid composition according to any one of Claims 1 to 3, wherein the film to be polished is a silicon oxide film formed in the process of manufacturing a semiconductor substrate.

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