JP7624837B2 - Polishing composition - Google Patents

Description

The present invention relates to a polishing composition.

The high integration brought about by the miniaturization of LSI manufacturing processes has led to improved performance in electronic devices, including computers, with smaller size, more functionality, and faster speeds. Chemical mechanical polishing (CMP) is used as a new microfabrication technology for the high integration of LSIs.

CMP has been applied to various steps in semiconductor manufacturing, and in one aspect, it is used to polish materials containing titanium atoms, such as TiN, and materials containing silicon atoms, such as single crystal silicon, polycrystalline silicon, silicon oxide, and silicon nitride, and there is a need to control the polishing rate of each material.

For example, Patent Document 1 discloses an aqueous chemical mechanical polishing composition containing a salt, soluble cerium, a carboxylic acid, and silica (particularly fumed silica) as a CMP slurry for polishing a substrate containing silicon atoms.

Special Publication No. 2001-507739

In a situation where there is a demand to control the polishing rate of each material, the objective of the present invention is to provide a new polishing composition that can polish materials containing silicon atoms at high speed.

In order to solve the above problems, the present inventors have conducted extensive research. As a result, they have found that the above problems can be solved by a polishing composition that contains abrasive grains, a polishing speed enhancer for an object to be polished that contains silicon atoms, and a liquid carrier, in which the surfaces of the abrasive grains are cationically modified, and the polishing speed enhancer contains an alpha-keto acid.

The present invention provides a novel polishing composition capable of polishing silicon-containing materials at high speed.

The present invention is described below. Note that the present invention is not limited to the following embodiments. Furthermore, unless otherwise specified, operations and measurements of physical properties are performed under room temperature (20-25°C) and relative humidity of 40-50% RH. Furthermore, it should be understood that all combinations of lower and upper limit values disclosed in this specification are disclosed. In other words, it should be understood that they can serve as a basis for correction.

<Polishing Composition>
In one embodiment of the present invention, there is provided a polishing composition comprising an abrasive grain, a polishing rate enhancer for a polishing object containing silicon atoms, and a liquid carrier, the abrasive grain having a surface cationically modified, and the polishing rate enhancer containing an alpha-keto acid. According to this embodiment, a novel polishing composition capable of polishing a material containing silicon atoms at high speed can be provided.

Below, we will explain each component that makes up the polishing composition.

[Abrasive grain]
In one embodiment of the present invention, the polishing composition contains abrasive grains, and the surfaces of the abrasive grains are cationically modified. If the abrasive grains having the surfaces cationically modified are not used, there is a risk that the intended effect of the present invention will not be achieved.

In one embodiment of the invention, the modification is by chemical bonding.

In one embodiment of the present invention, specific examples of the abrasive grains may be inorganic particles, organic particles, or organic-inorganic composite particles, but are preferably inorganic particles. Specific examples of inorganic particles include particles made of metal oxides such as silica, alumina, ceria, and titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. In one embodiment of the present invention, the abrasive grains are abrasive grains other than ceria. In one embodiment of the present invention, the abrasive grains are silica. As silica, fumed silica and colloidal silica are preferred, and colloidal silica is particularly preferred. Methods for producing colloidal silica include the sodium silicate method and the sol-gel method.

In one embodiment of the present invention, the surface of the abrasive grains is cationically modified. In one embodiment of the present invention, colloidal silica having a cationically modified surface is preferably colloidal silica having an amino group or a quaternary ammonium group fixed to the surface. Examples of a method for producing colloidal silica having such cationic groups include a method of fixing a silane coupling agent having an amino group such as aminoethyltrimethoxysilane, aminopropyltrimethoxysilane, aminoethyltriethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, or an silane coupling agent having a quaternary ammonium group such as N-trimethoxysilylpropyl-N,N,N-trimethylammonium to the surface of the abrasive grains, as described in JP-A-2005-162533. This makes it possible to obtain colloidal silica having an amino group or a quaternary ammonium group fixed to the surface. In one embodiment of the present invention, the abrasive grains are formed by fixing a silane coupling agent having an amino group or a silane coupling agent having a quaternary ammonium group to the surface of the abrasive grains.

In one embodiment of the present invention, the number of silanol groups per unit surface area of the abrasive grains (silanol group density) is more than 2.0/ ^nm2 . In one embodiment of the present invention, the number of silanol groups is 2.1/nm2 or ^more , 2.3/nm2 ^or more, 2.5/ ^nm2 or more, 2.7/nm2 ^{or more} , 2.9/nm2 or more, 3.1/ ^nm2 or more, 3.3/ ^nm2 or more, or 3.5/ ^nm2 or more. By having such a lower limit, the desired effect of the present invention can be efficiently achieved. In one embodiment of the present invention, the number of silanol groups per unit surface area of the abrasive grains (silanol group density) is less than 10/ ^nm2 , 8/nm2 ^or less, 6/nm2 or ^less , 5/nm2 ^or less, or 4/nm2 or ^less . By having such an upper limit, the technical effect of efficiently achieving the desired effect of the present invention can be achieved.

In one embodiment of the present invention, the number of silanol groups per unit surface area of the abrasive grains can be made to exceed 2.0/ ^nm2 by, for example, appropriately selecting a method for manufacturing the abrasive grains. If a commercially available product has a number of silanol groups per unit surface area of the abrasive grains that exceeds 2.0/ ^nm2 , that product may be purchased.

In one embodiment of the present invention, the silanol group density can be calculated by the following method after measuring or calculating each parameter by the following measurement method or calculation method.

In the formula below, C is the total mass of the abrasive grains, and S is the BET specific surface area of the abrasive grains. First, 1.50 g of abrasive grains as solids are collected in a 200 ml beaker, and 100 ml of pure water is added to make a slurry, after which 30 g of sodium chloride is added and dissolved. Next, 1 N hydrochloric acid is added to adjust the pH of the slurry to about 3.0 to 3.5, and pure water is added until the slurry becomes 150 ml. Using an automatic titration device (HIRANUMA SANGYO CO., LTD., COM-1700), this slurry is adjusted to pH 4.0 with 0.1 N sodium hydroxide at 25°C, and the volume V [L] of 0.1 N sodium hydroxide solution required to increase the pH from 4.0 to 9.0 by pH titration is measured. The silanol group density can be calculated using the formula below.

In the above formula,
ρ represents the silanol group density (groups/nm ² );
c represents the concentration (mol/L) of the sodium hydroxide solution used in the titration;
V is the volume (L) of sodium hydroxide solution required to raise the pH from 4.0 to 9.0.
represents;
N _A represents the Avogadro constant (mol);
C represents the total mass (solids) of the abrasive grains (g);
S represents the weighted average value (nm ² /g) of the BET specific surface area of the abrasive grains.

In one embodiment of the present invention, the average primary particle diameter of the abrasive grains is 5 nm or more, 10 nm or more, 12 nm or more, 14 nm or more, 16 nm or more, 18 nm or more, 20 nm or more, or 22 nm or more. In one embodiment of the polishing composition, the average primary particle diameter of the abrasive grains is 50 nm or less, 40 nm or less, 38 nm or less, 36 nm or less, less than 35 nm, 34 nm or less, 32 nm or less, 30 nm or less, 28 nm or less, 26 nm or less, or 24 nm or less. By being less than 35 nm, the intended effect of the present invention can be efficiently achieved. In one embodiment of the present invention, the method for measuring the average primary particle diameter of the abrasive grains may be the method described in the examples.

In one embodiment of the present invention, the average secondary particle diameter of the abrasive grains is 10 nm or more, 12 nm or more, 14 nm or more, 16 nm or more, 18 nm or more, 20 nm or more, 20 nm or more, 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, or 45 nm or more. In one embodiment of the polishing composition of the present invention, the average primary particle diameter of the abrasive grains is 100 nm or less, 90 nm or less, 80 nm or less, 75 nm or less, 70 nm or less, 65 nm or less, 60 nm or less, or 55 nm or less. In one embodiment of the present invention, the method for measuring the average secondary particle diameter of the abrasive grains may be the method described in the Examples.

In one embodiment of the present invention, the lower limit of the average degree of association (average secondary particle size/average primary particle size) of the abrasive grains in the polishing composition is 1.3 or more, 1.4 or more, 1.5 or more, more than 1.5, 1.6 or more, 1.7 or more, 1.8 or more, more than 1.8, 1.9 or more, 2.0 or more, or 2.1 or more. In particular, the expected effect of the present invention is efficiently achieved by having the average degree of association (average secondary particle size/average primary particle size) of the abrasive grains in the polishing composition exceed 1.5 or exceed 1.8. In one embodiment of the present invention, the upper limit of the average degree of association of the abrasive grains in the polishing composition is 4.0 or less, 3.5 or less, 3.3 or less, 3.1 or less, 2.9 or less, 2.7 or less, or 2.5 or less.

In one embodiment of the present invention, the content of the abrasive grains in the polishing composition is 0.01% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 0.9% by mass or more, 1.1% by mass or more, 1.3% by mass or more, 1.5% by mass or more, or 1.7% by mass or more, 1.8% by mass or more, more than 1.8% by mass, 2.0% by mass or more, 2.2% by mass or more, or 2.4% by mass or more. In one embodiment of the present invention, the content of the abrasive grains in the polishing composition is 10% by mass or less, 8% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, 3% by mass or less, less than 3% by mass, 2.8% by mass or less, 2.3% by mass or less, 2.1% by mass or less, or 1.9% by mass or less.

In one embodiment of the present invention, the zeta potential of the abrasive grains in the polishing composition is positive, specifically, more than 2 mV, 4 mV or more, 6 mV or more, 8 mV or more, 10 mV or more, 12 mV or more, 13 mV or more, 14 mV or more, 16 mV or more, 18 mV or more, 20 mV or more, or 22 mV or more. If the surface of the abrasive grains is not cationically modified, the zeta potential may be insufficient, and the intended effect of the present invention may not be achieved. In one embodiment of the present invention, the zeta potential of the abrasive grains in the polishing composition is 40 mV or less, 38 mV or less, 36 mV or less, 34 mV or less, 32 mV or less, less than 32 mV, 30 mV or less, 28 mV or less, 26 mV or less, 24 mV or less, 22 mV or less, 20 mV or less, 18 mV or less, 16 mV or less, or 14 mV or less. In particular, when it is less than 32 mV, the desired effect of the present invention is efficiently achieved.

[Polishing rate enhancer for polishing object containing silicon atoms]
In one embodiment of the present invention, the polishing composition contains an agent for improving the polishing rate of a silicon-containing object to be polished, and the agent for improving the polishing rate contains an α-keto acid. Thus, the present invention provides an agent for improving the polishing rate of a silicon-containing object to be polished, which contains an α-keto acid. In one embodiment of the present invention, the α-keto acid is one of the following:

wherein R ¹ is an alkyl group, a carboxylalkyl group or an alkoxycarbonylalkyl group.

In one embodiment of the present invention, the number of carbon atoms in the alkyl group is 1 to 5, 1 to 4, 1 to 3, or 1 or 2. Of these, from the viewpoint of efficiently achieving the intended effects of the present invention, it is preferable that the number of carbon atoms in the alkyl group is 1 or 2. In one embodiment of the present invention, the alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a t-butyl group, an n-pentyl group, or the like. Of these, from the viewpoint of efficiently achieving the intended effects of the present invention, it is preferable that the alkyl group is a methyl group or an ethyl group.

In one embodiment of the present invention, the number of carbon atoms in the alkyl group in the carboxylalkyl group is 1 to 5, 1 to 4, 1 to 3, or 1 or 2. In particular, from the viewpoint of efficiently achieving the intended effects of the present invention, the number of carbon atoms in the alkyl group in the carboxylalkyl group is preferably 1 or 2 or more, and more preferably 2 or more. In one embodiment of the present invention, the carboxylalkyl group is preferably a carboxylmethyl group, a carboxylethyl group, a carboxylpropyl group, a carboxylbutyl group, a carboxylpentyl group, or the like. In particular, from the viewpoint of efficiently achieving the intended effects of the present invention, a carboxylmethyl group or a carboxylethyl group is preferred, and a carboxylethyl group is more preferred.

In one embodiment of the present invention, the number of carbon atoms in the alkyl group in the alkoxycarbonylalkyl group is 1 to 5, 1 to 4, 1 to 3, or 1 or 2. In one embodiment of the present invention, the number of carbon atoms in the alkoxy group in the alkoxycarbonylalkyl group is 1 to 5, 1 to 4, 1 to 3, or 1 or 2. In one embodiment of the present invention, preferred alkoxycarbonylalkyl groups include methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylethyl, isopropoxycarbonylethyl, butoxycarbonylmethyl, isobutoxycarbonylethyl, tertiary butoxycarbonylmethyl, and pentyloxycarbonylmethyl groups.

In one embodiment of the present invention, the alpha-keto acid is at least one selected from the group consisting of pyruvic acid, 2-oxoglutaric acid, and oxalacetic acid.

In one embodiment of the present invention, the content of the polishing speed enhancer for the polishing object containing silicon atoms in the polishing composition is 0.01 mM or more, 0.05 mM or more, 0.1 mM or more, 0.5 mM or more, 1 mM or more, 2 mM or more, 4 mM or more, 5 mM or more, more than 5 mM, 5.5 mM or more, 6 mM or more, 8 mM or more, 10 mM or more, 10.5 mM or more, 12 mM or more, 14 mM or more, 16 mM or more, or 18 mM or more. In particular, when the content of the polishing speed enhancer for the polishing object containing silicon atoms in the polishing composition is more than 5 mM, the intended effect of the present invention is efficiently achieved. In one embodiment of the present invention, the content of the polishing speed enhancer for the polishing object containing silicon atoms in the polishing composition is 200 mM or less, 150 mM or less, 100 mM or less, 80 mM or less, 60 mM or less, 40 mM or less, 30 mM or less, 25 mM or less, 20 mM or less, less than 20 mM, 19.5 mM or less, 18 mM or less, 16 mM or less, 14 mM or less, 12 mM or less, 10 mM or less, 9.5 mM or less, 8 mM or less, or 7 mM or less. In particular, the content of the polishing speed enhancer for the polishing object containing silicon atoms in the polishing composition is less than 20 mM, thereby efficiently achieving the desired effect of the present invention.

The polishing speed enhancer of the present invention for a silicon-atom-containing object to be polished can also contribute to improving the polishing speed of a titanium-atom-containing object to be polished. In that sense, the present invention provides a polishing speed enhancer that contains an alpha-keto acid and that enhances the polishing speed of at least one of a silicon-atom-containing object to be polished and a titanium-atom-containing object to be polished.

[Oxidizing agent]
In one embodiment of the present invention, the polishing composition may contain an oxidizing agent.

In one embodiment of the present invention, the oxidizing agent is preferably a peroxide. Specific examples of such peroxides include, but are not limited to, hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, and potassium monopersulfate. The above oxidizing agents may be used alone or in combination of two or more.

In one embodiment of the present invention, the lower limit of the content (active ingredient concentration) of the oxidizing agent in the polishing composition (total if two or more types) is 0.001 mass% or more, 0.005 mass% or more, 0.01 mass% or more, or 0.05 mass% or more. In one embodiment of the present invention, the upper limit of the content (active ingredient concentration) of the oxidizing agent in the polishing composition (total if two or more types) is 10 mass% or less, 5 mass% or less, 3 mass% or less, 2 mass% or less, or 1 mass% or less.

[Liquid Carrier]
In one embodiment of the present invention, the polishing composition includes a liquid carrier. The liquid carrier has a function of dispersing or dissolving each component. In one embodiment of the present invention, when the liquid carrier includes an organic solvent, the content of the organic solvent is less than 7% by mass, 6% by mass or less, 4% by mass or less, 2% by mass or less, or 1% by mass or less. The organic solvent may be, for example, at least one selected from the group consisting of monoalcohols, dialcohols, and cellosolves. In one embodiment of the present invention, the liquid carrier is only water. In one embodiment of the present invention, the water is preferably water that contains as few impurities as possible from the viewpoint of preventing contamination of the polishing object and the action of other components. Here, the purity of the water can be increased by, for example, removing impurity ions using an ion exchange resin, removing foreign matter with a filter, distillation, or other operations. Specifically, it is preferable to use, for example, deionized water (ion-exchanged water), pure water, ultrapure water, distilled water, etc. as the water.

[pH of polishing composition]
In one embodiment of the present invention, the pH of the polishing composition is more than 2.5, 2.6 or more, 2.7 or more, 2.8 or more, 2.9 or more, 3.0 or more, 3.2 or more, 3.5 or more, 3.8 or more, 4.0 or more, 4.5 or more, 5.0 or more, 5.5 or more, or 5.8 or more. If the pH of the polishing composition is 2.5 or less, the expected effect of the present invention may not be achieved. In one embodiment of the present invention, the pH of the polishing composition is 11 or less, 9 or less, 7 or less, less than 7, 6.8 or less, 6.6 or less, 6.4 or less, 6.2 or less, 6 or less, less than 6, 5.8 or less, 5.6 or less, 5.4 or less, 5.2 or less, 5 or less, 4.8 or less, 4.6 or less, 4.4 or less, 4.2 or less, 4 or less, less than 4, 3.8 or less, 3.6 or less, 3.4 or less, or 3.2 or less. In this specification, the pH of the polishing composition can be measured according to the method described in the Examples.

In one embodiment of the present invention, the polishing composition contains a pH adjuster. The pH adjuster may be an acid, a base, or a salt thereof.

In one embodiment of the present invention, the acid may be an inorganic acid such as periodic acid, hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, or phosphoric acid, or an organic acid such as citric acid, lactic acid, diglycolic acid, furoic acid, methoxyacetic acid, methoxyphenylacetic acid, or phenoxyacetic acid.

In one embodiment of the present invention, examples of the base include amines such as aliphatic amines and aromatic amines, ammonium solutions, organic bases such as quaternary ammonium hydroxides, hydroxides of alkali metals such as potassium hydroxide, hydroxides of Group 2 elements, amino acids such as histidine, and ammonia.

According to one embodiment of the present invention, the content of the pH adjuster in the polishing composition can be appropriately adjusted to obtain the desired pH.

[Polished object]
In one embodiment of the present invention, the object to be polished includes silicon atoms. Examples of objects to be polished that include silicon atoms include single crystal silicon, polycrystalline silicon, silicon oxide, silicon nitride, and the like. In one embodiment of the present invention, the object to be polished that includes silicon atoms is doped with at least one trivalent element (e.g., boron, gallium, indium, and the like). In one embodiment of the present invention, the object to be polished includes titanium atoms. Examples of objects to be polished that include titanium atoms include titanium nitride, titanium, titanium alloys, and the like.

In the present invention, the polishing composition contains an alpha-keto acid, thereby improving the polishing rate of an object to be polished that contains silicon atoms. In one embodiment of the present invention, the polishing composition contains an alpha-keto acid, thereby improving the polishing rate of an object to be polished that contains titanium atoms. Thus, in the present invention, an agent for improving the polishing rate of an object to be polished that contains silicon atoms, which agent contains an alpha-keto acid, is provided. In addition, in the present invention, an agent for improving the polishing rate of an object to be polished that contains titanium atoms, which agent contains an alpha-keto acid, is provided.

[Other Additives]
In one embodiment of the present invention, the polishing composition may or may not contain other additives.Specific examples of other additives include complexing agents, metal anticorrosives, preservatives, antifungal agents, reducing agents, water-soluble polymers, organic solvents for dissolving poorly soluble organic matter, etc.The term "not containing" used in this specification also includes the case where the corresponding component is not contained at all in the polishing composition, and the case where the corresponding component is contained in an amount of 0.5 mass ppm or less.

Among the other additives mentioned above, we will explain the complexing agents, metal corrosion inhibitors, preservatives, and fungicides.

(Complexing Agent)
The complexing agent has the effect of chemically etching the surface of the object to be polished, and can more effectively increase the polishing rate of the object to be polished with the polishing composition.

Examples of complexing agents include inorganic acids or their salts, organic acids or their salts, nitrile compounds, amino acids, and chelating agents. These complexing agents may be used alone or in combination of two or more. The complexing agents may be commercially available products or synthetic products.

As the complexing agent, a salt of the inorganic acid or the organic acid may be used. In particular, when a salt of a weak acid and a strong base, a salt of a strong acid and a weak base, or a salt of a weak acid and a weak base is used, a pH buffering effect can be expected.

Examples of such salts include potassium chloride, sodium sulfate, potassium nitrate, potassium carbonate, potassium tetrafluoroborate, potassium pyrophosphate, potassium oxalate, trisodium citrate, (+)-potassium tartrate, potassium hexafluorophosphate, etc.

Specific examples of nitrile compounds include acetonitrile, aminoacetonitrile, propionitrile, butyronitrile, isobutyronitrile, benzonitrile, glutaronitrile, and methoxyacetonitrile.

Specific examples of amino acids include glycine, α-alanine, β-alanine, N-methylglycine, N,N-dimethylglycine, 2-aminobutyric acid, norvaline, valine, leucine, norleucine, isoleucine, phenylalanine, proline, sarcosine, ornithine, lysine, taurine, serine, threonine, homoserine, tyrosine, bicine, tricine, 3,5-diiodo-tyrosine, β-(3,4-dihydroxyphenyl)-alanine, thyroxine, These include 4-hydroxy-proline, cysteine, methionine, ethionine, lanthionine, cystathionine, cystine, cysteic acid, aspartic acid, glutamic acid, S-(carboxymethyl)-cysteine, 4-aminobutyric acid, asparagine, glutamine, azaserine, arginine, canavanine, citrulline, delta-hydroxy-lysine, creatine, histidine, 1-methyl-histidine, 3-methyl-histidine, and tryptophan.

Specific examples of chelating agents include nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), N-(2-carboxylate ethyl)-L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid, and 1,2-dihydroxybenzene-4,6-disulfonic acid.

When the polishing composition contains a complexing agent, the content (active ingredient concentration) of the complexing agent is not particularly limited. For example, the lower limit of the content (active ingredient concentration) of the complexing agent is not particularly limited because even a small amount is effective, but it is preferably 0.001 g/L or more, more preferably 0.01 g/L or more, and even more preferably 1 g/L or more. The upper limit of the content (active ingredient concentration) of the complexing agent is preferably 20 g/L or less, more preferably 15 g/L or less, and even more preferably 10 g/L or less. If it is in such a range, the polishing speed of the object to be polished is improved, and it is advantageous in improving the smoothness of the surface of the object to be polished after polishing with the polishing composition.

(Metal corrosion inhibitor)
Metal corrosion inhibitors act to prevent the dissolution of metals, thereby suppressing deterioration of the surface condition, such as roughening of the polished surface.

The metal corrosion inhibitor is a heterocyclic compound or a surfactant. The number of members of the heterocyclic ring in the heterocyclic compound is not particularly limited. The heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. The metal corrosion inhibitor may be used alone or in combination of two or more kinds. The metal corrosion inhibitor may be a commercially available product or a synthetic product.

Specific examples of heterocyclic compounds include nitrogen-containing heterocyclic compounds such as pyrrole compounds, pyrazole compounds, imidazole compounds, triazole compounds, tetrazole compounds, pyridine compounds, pyrazine compounds, pyridazine compounds, pyrindine compounds, indolizine compounds, indole compounds, isoindole compounds, indazole compounds, purine compounds, quinolizine compounds, quinoline compounds, isoquinoline compounds, naphthyridine compounds, phthalazine compounds, quinoxaline compounds, quinazoline compounds, cinnoline compounds, buteridine compounds, thiazole compounds, isothiazole compounds, oxazole compounds, isoxazole compounds, and furazan compounds.

More specifically, examples of pyrazole compounds include 1H-pyrazole, 4-nitro-3-pyrazole carboxylic acid, 3,5-pyrazole carboxylic acid, 3-amino-5-phenylpyrazole, 5-amino-3-phenylpyrazole, 3,4,5-tribromopyrazole, 3-aminopyrazole, 3,5-dimethylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3-methylpyrazole, 1-methylpyrazole, 3-amino-5-methylpyrazole, 4-amino-pyrazolo[3,4-d]pyrimidine, allopurinol, 4-chloro-1H-pyrazolo[3,4-D]pyrimidine, 3,4-dihydroxy-6-methylpyrazolo(3,4-B)-pyridine, and 6-methyl-1H-pyrazolo[3,4-b]pyridin-3-amine.

Examples of imidazole compounds include imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, benzimidazole, 5,6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole, 2-methylbenzimidazole, 2-(1-hydroxyethyl)benzimidazole, 2-hydroxybenzimidazole, 2-phenylbenzimidazole, 2,5-dimethylbenzimidazole, 5-methylbenzimidazole, and 5-nitrobenzimidazole.

Examples of triazole compounds include 1,2,3-triazole (1H-BTA), 1,2,4-triazole, 1-methyl-1,2,4-triazole, methyl-1H-1,2,4-triazole-3-carboxylate, 1,2,4-triazole-3-carboxylic acid, methyl 1,2,4-triazole-3-carboxylate, 1H-1,2,4-triazole-3-thiol, 3,5-diamino-1H-1,2,4-triazole, 3-amino-1,2,4 -triazole-5-thiol, 3-amino-1H-1,2,4-triazole, 3-amino-5-benzyl-4H-1,2,4-triazole, 3-amino-5-methyl-4H-1,2,4-triazole, 3-nitro-1,2,4-triazole, 3-bromo-5-nitro-1,2,4-triazole, 4-(1,2,4-triazol-1-yl)phenol, 4-amino-1,2,4-triazole, 4-amino-3,5-dipropyl-4H-1,2,4- triazole, 4-amino-3,5-dimethyl-4H-1,2,4-triazole, 4-amino-3,5-dipeptyl-4H-1,2,4-triazole, 5-methyl-1,2,4-triazole-3,4-diamine, 1H-benzotriazole, 1-hydroxybenzotriazole, 1-aminobenzotriazole, 1-carboxybenzotriazole, 5-chloro-1H-benzotriazole, 5-nitro-1H-benzotriazole, 5-carboxy-1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, 1-(1',2'-dicarboxyethyl)benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]-5-methylbenzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]-4-methylbenzotriazole, etc.

Examples of tetrazole compounds include 1H-tetrazole, 5-methyltetrazole, 5-aminotetrazole, and 5-phenyltetrazole.

Examples of indazole compounds include 1H-indazole, 5-amino-1H-indazole, 5-nitro-1H-indazole, 5-hydroxy-1H-indazole, 6-amino-1H-indazole, 6-nitro-1H-indazole, 6-hydroxy-1H-indazole, and 3-carboxy-5-methyl-1H-indazole.

Examples of indole compounds include 1H-indole, 1-methyl-1H-indole, 2-methyl-1H-indole, 3-methyl-1H-indole, 4-methyl-1H-indole, 5-methyl-1H-indole, 6-methyl-1H-indole, 7-methyl-1H-indole, 4-amino-1H-indole, 5-amino-1H-indole, 6-amino-1H-indole, 7-amino-1H-indole, 4-hydro ... 1H-indole, 5-hydroxy-1H-indole, 6-hydroxy-1H-indole, 7-hydroxy-1H-indole, 4-methoxy-1H-indole, 5-methoxy-1H-indole, 6-methoxy-1H-indole, 7-methoxy-1H-indole, 4-chloro-1H-indole, 5-chloro-1H-indole, 6-chloro-1H-indole, 7-chloro-1H-indole, 4-carboxy-1H- Indole, 5-carboxy-1H-indole, 6-carboxy-1H-indole, 7-carboxy-1H-indole, 4-nitro-1H-indole, 5-nitro-1H-indole, 6-nitro-1H-indole, 7-nitro-1H-indole, 4-nitrile-1H-indole, 5-nitrile-1H-indole, 6-nitrile-1H-indole, 7-nitrile-1H-indole, 2,5-dimethyl-1H-indole , 1,2-dimethyl-1H-indole, 1,3-dimethyl-1H-indole, 2,3-dimethyl-1H-indole, 5-amino-2,3-dimethyl-1H-indole, 7-ethyl-1H-indole, 5-(aminomethyl)indole, 2-methyl-5-amino-1H-indole, 3-hydroxymethyl-1H-indole, 6-isopropyl-1H-indole, 5-chloro-2-methyl-1H-indole, etc.

Surfactants used as metal corrosion inhibitors include anionic surfactants, cationic surfactants, and amphoteric surfactants.

Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, alkyl ether sulfates, alkyl benzene sulfonates, alkyl phosphates, polyoxyethylene alkyl phosphates, polyoxyethylene sulfosuccinic acids, alkyl sulfosuccinic acids, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonic acids, and salts thereof.

Examples of cationic surfactants include alkyl dimethyl ammonium salts, alkyl benzyl dimethyl ammonium salts, and alkyl amine salts.

Examples of amphoteric surfactants include alkyl betaines and alkyl amine oxides.

Specific examples of nonionic surfactants include polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkyl amines, and alkyl alkanolamides.

When the polishing composition contains a metal corrosion inhibitor, the content (active ingredient concentration) of the metal corrosion inhibitor is not particularly limited. For example, the lower limit of the content (active ingredient concentration) of the metal corrosion inhibitor is preferably 0.001 g/L or more, more preferably 0.005 g/L or more, and even more preferably 0.01 g/L or more. The upper limit of the content (active ingredient concentration) of the metal corrosion inhibitor is preferably 10 g/L or less, more preferably 5 g/L or less, and even more preferably 2 g/L or less. Within such a range, dissolution of the metal can be prevented and deterioration of the surface condition, such as roughness of the polished surface, can be suppressed.

(Preservatives and fungicides)
Furthermore, examples of preservatives and antifungal agents that may be contained in the polishing composition if necessary include isothiazoline preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, paraoxybenzoic acid esters, phenoxyethanol, etc. These preservatives and antifungal agents may be used alone or in combination of two or more kinds.

[Electrical Conductivity (EC) of Polishing Composition]
According to one embodiment of the present invention, the lower limit of the electrical conductivity (EC) of the polishing composition is 0.01 mS/cm or more, 0.1 mS/cm or more, 0.2 mS/cm or more, 0.3 mS/cm or more, 0.4 mS/cm or more, 0.5 mS/cm or more, 0.6 mS/cm or more, 0.8 mS/cm or more, or 1.0 mS/cm or more. According to one embodiment of the present invention, the upper limit of the electrical conductivity (EC) of the polishing composition is 10 mS/cm or less, 5 mS/cm or less, 3 mS/cm or less, 2 mS/cm or less, 1.8 mS/cm or less, 1.5 mS/cm or less, 1.2 mS/cm or less, 1 mS/cm or less, 0.8 mS/cm or less, or 0.6 mS/cm or less. The electrical conductivity of the polishing composition can be adjusted by appropriately changing the content of a pH adjuster, a polishing rate enhancer, etc. The electrical conductivity of the polishing composition is a value measured by a tabletop electrical conductivity meter (manufactured by Horiba, Ltd., model number: DS-71).

[Particularly preferred combinations of embodiments of the polishing composition]
As described above, it must be understood that all combinations of the embodiments are disclosed in the present application, but particularly preferred combinations of the embodiments of the polishing composition will be described below.

That is, according to one embodiment of the present invention, the content of the abrasive grains is more than 1.8 mass%. In the polishing composition of one embodiment of the present invention, the average primary particle size of the abrasive grains is less than 35 nm, and the number of silanol groups per unit surface area of the abrasive grains (silanol group density) is less than 5.7/ ^nm2 . According to one embodiment of the present invention, the pH of the polishing composition is more than 2.5. In one embodiment of the present invention, the content of the polishing rate enhancer for a polishing object containing silicon atoms in the polishing composition is more than 5 mM. In one embodiment of the present invention, the content of the polishing rate enhancer for a polishing object containing silicon atoms in the polishing composition is less than 20 mM.

<Method of producing polishing composition>
According to one embodiment of the present invention, the method for producing the polishing composition is not particularly limited. The method for producing the polishing composition includes, for example, mixing an abrasive grain, a polishing rate enhancer for an object to be polished that contains silicon atoms, and a liquid carrier, the abrasive grain having a cation-modified surface, and the polishing rate enhancer containing an alpha-keto acid. The temperature at which each component is mixed is not particularly limited, but is preferably 10 to 40°C, and may be heated to increase the dissolution rate. The mixing time is also not particularly limited.

<Polishing method and substrate manufacturing method>
In the present invention, a method for polishing an object to be polished is provided, which comprises polishing the object to be polished using the above-mentioned polishing composition.In addition, in the present invention, a method for manufacturing a substrate is provided, which comprises polishing a substrate before polishing using the above-mentioned polishing method.In one embodiment of the present invention, the substrate is preferably one of the objects listed in the above [object to be polished].

In one embodiment of the present invention, the polishing method can be carried out using a polishing device.

As a polishing device, a general polishing device can be used that is equipped with a holder for holding a substrate or the like having an object to be polished, a motor whose rotation speed can be changed, and a polishing platen onto which a polishing pad (polishing cloth) can be attached.

The polishing pad can be made of any material, including general nonwoven fabric, polyurethane, and porous fluororesin, without any particular restrictions. It is preferable that the polishing pad has grooves that allow the polishing liquid to accumulate.

There are no particular limitations on the polishing conditions. For example, the rotation speed of the polishing platen is preferably 10 to 500 rpm, and the pressure applied to the substrate carrying the object to be polished (polishing pressure) is preferably 0.5 to 10 psi.

There are no particular limitations on the method of supplying the polishing composition to the polishing pad, and for example, a method of continuously supplying it using a pump or the like is used. There is no limit to the amount of supply, but it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

After polishing is complete, the substrate is washed with running water, and the water droplets adhering to the substrate are removed using a spin dryer or the like, followed by drying to obtain the substrate.

The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively. In the following examples, unless otherwise specified, the operations were carried out under the conditions of room temperature (25°C) and relative humidity of 40 to 50% RH.

<Preparation of Polishing Composition>
The polishing composition was prepared by stirring and mixing in water (mixing temperature: about 25° C., mixing time: about 10 minutes) the abrasive grains having amino groups fixed on the surface thereof, the polishing rate enhancer (the comparative example is a similar substance), the pH adjuster, and 3.0 g/kg of an oxidizing agent (31% H ₂ O ₂ ) of the composition shown in Table 1. Note that "-" in Table 1 means that the component was not added.

<Average primary particle size of abrasive grains>
The average primary particle size of the abrasive grains was calculated from the specific surface area of the abrasive grains measured by the BET method using "Flow SorbII 2300" manufactured by Micromeritics, and the density of the abrasive grains.

<Average secondary particle size of abrasive grains>
The average secondary particle size of the abrasive grains was calculated by dynamic light scattering method measured using "UPA-UT151" manufactured by Microtrac.

<pH of Polishing Composition>
The pH of the polishing composition was determined by using a glass electrode type hydrogen ion concentration indicator (Model No.: F-23, manufactured by Horiba, Ltd.) and performing three-point calibration using standard buffer solutions (phthalate pH buffer solution, pH: 4.01 (25°C), neutral phosphate pH buffer solution, pH: 6.86 (25°C), carbonate pH buffer solution, pH: 10.01 (25°C)), then placing the glass electrode in the polishing composition and measuring the value after stabilization for at least 2 minutes.

<Zeta potential of abrasive grains>
The polishing composition was subjected to ELS-Z2 manufactured by Otsuka Electronics Co., Ltd., and measurement was performed by a laser Doppler method (electrophoretic light scattering measurement method) using a flow cell at a measurement temperature of 25° C. The obtained data was analyzed by the Smoluchowski formula to calculate the zeta potential of the abrasive grains in the polishing composition.

<Polishing speed>
The object to be polished is
・200 mm wafer (TEOS (silicon oxide film)),
・200 mm wafer (SiN (silicon nitride film)),
・200 mm wafer (TiN (titanium nitride) film),
was prepared.

Polishing was performed using the polishing composition under the following polishing conditions. The polishing rate of TEOS was determined by measuring the thickness (film thickness) of the object to be polished before and after polishing using a manual sheet resistance meter (VR-120, manufactured by Hitachi Kokusai Electric Inc.) and dividing the difference in the thickness (film thickness) of the object to be polished before and after polishing by the polishing time (min). The polishing rate of TiN film was determined by dividing the difference in the thickness (Å) of TiN blanket wafer before and after polishing measured using a sheet resistance meter based on the DC four-point probe method by the polishing time (min). The polishing rate of SiN film was determined by dividing the difference in the thickness (Å) of SiN blanket wafer before and after polishing measured using an optical interference film thickness meter (manufactured by Filmetrics Inc.: model number Filmetrics F50) by the polishing time (min).

(Polishing conditions)
Polishing machine: Single-sided CMP polishing machine (ENGIS)
Polishing pad: Polyurethane pad (IC1010: manufactured by Rohm and Haas Company)
Pressure: 3.4 psi
Platen (surface plate) rotation speed: 100 rpm
Head (carrier) rotation speed: 100 rpm
Flow rate of polishing composition: 100 ml/min
Dress: Diamond Disk (in-situ condition).

Claims (11)

Abrasive grains and
an agent for increasing the polishing speed of an object to be polished, the agent including silicon atoms;
A liquid carrier;
Including,
the abrasive grains have surfaces that are cationically modified;
A polishing composition for polishing an object containing silicon atoms , wherein the polishing rate enhancer comprises an α-keto acid. The polishing composition according to claim 1, wherein the pH is greater than 2.5. The polishing composition according to claim 1 or 2 , for polishing an object to be polished which further contains titanium atoms. The polishing composition according to any one of claims 1 to 3 , wherein the number of silanol groups per unit surface area of the abrasive grains is more than 2.0/ ^nm2 . 5. The polishing composition according to claim 1, wherein when the liquid carrier contains an organic solvent, the content of the organic solvent is less than 7 mass %. The polishing composition according to any one of claims 1 to 5 , wherein the degree of association of the abrasive grains is more than 1.8. The polishing composition according to any one of claims 1 to 6 , wherein the abrasive grains have a positive zeta potential. The polishing composition according to any one of claims 1 to 7 , wherein the abrasive grains are abrasive grains other than ceria. The polishing composition according to claim 8 , wherein the abrasive is silica. The alpha keto acid is selected from the group consisting of:

10. The polishing composition according to claim 1, wherein R ¹ is an alkyl group, a carboxylalkyl group, or an alkoxycarbonylalkyl group. 11. The polishing composition according to claim 10 , wherein the α-keto acid is at least one selected from the group consisting of pyruvic acid, 2-oxoglutaric acid, and oxalacetic acid.