Polishing composition using highly water-affinity polishing particles containing a basic substance

Abstract

[Problem] To provide a polishing composition that is for use in CMP polishing and that makes it possible to minimize the occurrence of defects. [Solution] A polishing composition containing silica particles, a nitrogen-containing organic compound that is basic, and water as a solvent, in which the Rsp value represented by formula (1) as calculated from a pulse NMR measurement value is greater than 0.7 and equal to or less than 6. Formula (1): Rsp = (Rav - Rb) / (Rb) (in formula (1), Rsp is an index indicating water affinity, Rav is the reciprocal of the relaxation time of the polishing composition, and Rb is the reciprocal of the relaxation time of the water serving as a solvent in the polishing composition).

Description

Technical Field

[0001] The present invention relates to a polishing composition using silica-based abrasive grains and a polishing method.

Background Art

[0002] A polishing composition using silica-based abrasive grains is used for polishing silicon wafers. In recent years, with the multi-layer wiring of the semiconductor substrate surface, when forming a device, a silicon oxide film or a metal wiring is embedded on a stepped substrate and flattened, and then lithography is further performed on the surface to form multi-layer wiring and manufacture an integrated circuit. As the high integration of patterns progresses, the miniaturization of patterns further advances, and the actinic rays used in lithography become near ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays. The exposure wavelength of the resist also becomes shorter, such as 248 nm, 193 nm, 157 nm, 13.6 nm, and furthermore, electron beam lithography is also being used. When lithography is performed several times due to multi-layer wiring, when the exposure wavelength used in lithography is short, if the polished surface is not highly flattened, specular reflection of the exposure light occurs at the interface between the resist and the substrate on the surface, and a rectangular resist pattern cannot be formed, and the resist pattern cannot be transferred to the lower layer. Therefore, it is desired that the polishing composition not only improves the polishing rate but also reduces defects (defects) caused by scratches and residual foreign matter on the polished surface. These polishing compositions contain silica-based abrasive grains, alkaline components, water-soluble compounds, chelating agents, oxidizing agents, metal corrosion inhibitors, etc. in an aqueous medium.

[0003] A polishing composition is disclosed in which silica particles as abrasive grains are defined using a function indicating the affinity with water obtained from the relationship between the reciprocal of the relaxation time of pulsed NMR and the total surface area of the silica particles (see Patent Document 1). A polishing composition is disclosed in which the relationship between the BET specific surface area of silica particles contained in abrasive grains and the specific surface area by the pulsed NMR method is defined (see Patent Document 2). Polishing compositions in which the solvent affinity of abrasive particles is evaluated by NMR relaxation time have been disclosed (see Patent Documents 3 and 4). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International public brochure WO2018 / 116890 [Patent Document 2] International Open Pamphlet WO2015 / 152151 [Patent Document 3] Japanese Patent Publication No. 2017-117894 [Patent Document 4] International Open Pamphlet WO2018 / 012174 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention, as claimed in this application, focuses on the affinity of silica particles used as abrasive grains to the aqueous medium of the polishing composition, and defines a parameter value that serves as an indicator of affinity. It was found that by combining silica particles with a basic nitrogen-containing organic compound and finding the optimal value of affinity, the polishing speed is improved and the polished surface becomes good. In other words, the objective is to suppress the occurrence of defects (residual foreign matter and scratches remaining on the polished surface) when used in CMP polishing of device wafers. [Means for solving the problem]

[0006] The present invention, in first aspect, is a polishing composition comprising silica particles, a basic nitrogen-containing organic compound, and water as a solvent, wherein the Rsp value represented by the following formula (1), calculated from pulsed NMR measurements, is greater than 0.7 and less than or equal to 6. Rsp = (Rav - Rb) / (Rb) ... (1) (In formula (1), Rsp is an index indicating water affinity, Rav is the reciprocal of the relaxation time of the polishing composition, and Rb is the reciprocal of the relaxation time of water, which is the solvent of the polishing composition.) From a second perspective, the polishing composition described in the first perspective, wherein the average primary particle diameter of silica particles measured by nitrogen gas adsorption is 5 to 80 nm, and the average particle diameter of silica particles measured by dynamic light scattering is 12 to 200 nm. A third aspect is the polishing composition according to the first or second aspect, wherein the basic nitrogen-containing organic compound is an aliphatic linear or cyclic amine which may contain a hydroxyl group, a carboxyl group, or a combination thereof, and the amine is a primary amine, a secondary amine, a tertiary amine, or a combination thereof. As a fourth viewpoint, the polishing composition according to any one of the first to third viewpoints, wherein the basic nitrogen-containing organic compound is a molecule having a molecular weight of 60 to 350. The fifth aspect is the polishing composition according to any one of the first to fourth aspects, wherein the basic nitrogen-containing organic compound is a secondary or tertiary linear aliphatic amine. As a sixth aspect, the polishing composition according to the first or second aspect, wherein the basic nitrogen-containing organic compound is N-ethylethylenediamine or triethylamine. As a seventh aspect, an abrasive composition according to any one of the first to sixth aspects, comprising an alkali metal hydroxide consisting of NaOH or KOH or ammonia and a basic nitrogen-containing organic compound, or a salt thereof, wherein (number of moles of the basic nitrogen-containing organic compound or its salt) > (number of moles of the alkali metal hydroxide consisting of NaOH or KOH or ammonia or its salt), and having an electrical conductivity of 100 to 650 μS / cm when the SiO2 concentration is 10% by mass, As the eighth aspect, the polishing composition according to any one of the first to seventh aspects further comprises a pH adjuster consisting of an inorganic acid, an organic acid, an alkali metal hydroxide, an ammonium salt, an ammonia, or a combination thereof. As a ninth point, the polishing composition according to any one of the first to eighth points further includes an aminocarboxylic acid-based chelating agent, a phosphonic acid-based chelating agent, or a chelating agent consisting of a combination thereof. As the tenth aspect, an abrasive composition according to any one of the first to ninth aspects, wherein the pH is 1 to 12. As the eleventh aspect, a polishing composition according to any one of the first to tenth aspects, used for polishing silicon wafers, device wafers, or Si-containing substrates. As the twelfth aspect, a method for producing an abrasive composition according to any one of the first to eleventh aspects, comprising a method of mixing a silica sol obtained by any one of the following steps (a) to (d) with the basic nitrogen-containing organic compound (A), or a method of dispersing the silica sol and the basic nitrogen-containing organic compound in an aqueous medium (B), (a) Step: A process in which an aqueous sodium silicate solution is subjected to ion exchange, and the resulting activated silicate solution is heat-treated to obtain silica sol. (b) Step: Step to obtain silica sol by hydrolysis of alkoxysilane. (c) Step: A step to obtain silica sol by wet grinding of silica powder in an aqueous medium. (d) Step: A step to obtain silica sol by dispersing silica powder obtained by combustion hydrolysis of silicon tetrachloride in a flame in an aqueous medium. The 13th aspect is a method for producing the polishing composition according to the 12th aspect, wherein the aqueous sodium silicate solution and / or activated silicate solution used in step (a) are filtered in advance, The 14th aspect is a method for producing the polishing composition described in the 12th or 13th aspect, wherein the rate of change in the average particle size measured by dynamic light scattering before and after the addition of a basic nitrogen-containing organic compound is less than 20%. As the 15th aspect, a polishing method is provided in which a TEOS film-coated wafer is polished for 60 seconds using a polishing composition described in any one of the 1st to 11th aspects, thereby reducing the number of defects of 180 nm or more per square centimeter to 1.4 or less, and The 16th aspect is the polishing method described in the 15th aspect, wherein the TEOS film-coated wafer is a 300 mm wafer. [Effects of the Invention]

[0007] This invention focuses on the affinity (water affinity) of silica particles used as abrasive grains in an aqueous medium of an abrasive composition, and defines a parameter value that serves as an indicator of affinity. It was found that by combining silica particles with a basic nitrogen-containing organic compound and finding the optimal affinity value, the polishing speed can be improved and defects occurring on the polished surface can be reduced. Defects occur on stepped substrates due to scratching or the adhesion of foreign matter. While the exact cause of scratching is not clearly understood, it is thought to originate from both the abrasive grains and the workpiece, and these coexist. If defects exist on the polished surface, they can cause diffuse reflection and defocusing of the resist exposure light during lithography, preventing the formation of rectangular patterns. This can then act as a mask during substrate processing, generating etching resistance and causing substrate processing defects, resulting in defects in semiconductor device manufacturing. Therefore, reducing defects is necessary. Improving polishing speed and flattening the polished surface are conflicting effects and difficult to achieve simultaneously. However, by adjusting the silica particles to a specific range of water affinity, we were able to maintain polishing speed while reducing defects.

[0008] The polishing composition contains silica particles as abrasive grains. Depending on the surface condition, the silica particles interact with the aqueous medium in the polishing composition, which affects the polishing speed and the flattening of the polished surface. In abrasive compositions, the water present on the surface of silica particles can be divided into free water and bound water. Free water exists around the silica particles but is not bound to them and remains in a free state. Bound water is attached to the silica particles by hydrogen bonds through silanol groups on the silica particle surface. Bound water plays an important role in ensuring good contact between the silica particles and water.

[0009] The state of water can be understood from the measurement of the relaxation time of protons in water molecules. Relaxation includes the process of releasing the absorbed energy and the process of the phase of the precession motion of nuclear spins becoming disordered from the state where they are aligned. The former is called spin-lattice relaxation (longitudinal relaxation), and its relaxation time is T1, and the latter is called spin-spin relaxation (transverse relaxation), and its relaxation time is T2. In T1 relaxation, relaxation is most likely to occur when the speed of molecular motion is about the same as the resonance frequency. The response time, that is, the relaxation time, of free water molecules not in contact with silica particles and water molecules in contact with silica particles to magnetic field changes is different. A short relaxation time is considered to mean that the surface of the particles in contact with water is large and the dispersibility of the particles is high.

[0010] Also, T2 relaxation occurs due to magnetic interaction. The measurement of the relaxation time by pulsed NMR can be said to be a measurement method that utilizes the difference in T2 relaxation. The existence of this bound water and additives within a specific range effectively functions in polishing to reduce the polishing rate, reduce scratches on the polished surface, and reduce defects. As described above, the pulsed NMR method is an analytical method that utilizes the fact that the relaxation times are different because the responses of the solvent molecules adsorbed on the particle surface (in this case, water) and the free solvent molecules not adsorbed on the silica particle surface to changes in the magnetic field are different. The movement of the solvent molecules adsorbed on the silica particle surface is restricted, but the solvent molecules not adsorbed on the silica particle surface can move freely. Therefore, the relaxation time of the solvent molecules adsorbed on the silica particle surface is shorter than that of the solvent molecules not adsorbed on the silica particle surface. Therefore, in a state where many water molecules are adsorbed on the silica particle surface, the Rsp value of pulsed NMR becomes high.

[0011] In the present invention, it is considered that the basic nitrogen-containing organic compound promotes the polarization of the silanol group and adsorbs more water molecules on the silica particle surface. Silica particles having an Rsp value within the scope of the present invention have a certain amount of silanol groups showing hydrophilicity on the surface of the silica particles. Since these silanol groups adsorb water molecules and amine molecules through hydrogen bonding to coat the silica particles, it is considered that the silica particles coated with water molecules and amine molecules do not cause scratches or defects on the polishing surface regardless of the particle size, thus suppressing the generation of defects. Even in that case, since water molecules and amine molecules separate from the silica particles due to a certain change in electrical conductivity, a certain level of electrical conductivity is more preferable.

[0012] The present invention provides a polishing composition containing silica particles having a specific Rsp value and amine molecules, in which water molecules and amine molecules coat the surface of the silica particles, suppressing the generation of scratches and defects on the polishing surface. In addition, the addition of a basic nitrogen-containing organic compound contributes to improving the dispersibility of the silica particles with less aggregation. Since the silica particles exist in a state close to monodispersion, the number of silanol groups on the surface of the silica particles increases, which also leads to an increase in the Rsp value. In the present invention, the change rate of the average particle diameter by the dynamic light scattering method before and after the addition of the basic nitrogen-containing organic compound is within 20%, or within 15%. It is considered that these factors suppress the generation of scratches and residual foreign matters on the polishing surface.

[0013] In the present invention, the number of defects of 180 nm or more on the wafer with a TEOS film after polishing can be 1000 or less per 300 mm wafer. That is, the number of defects of 180 nm or more per polishing surface (1 square centimeter) can be 1.4 or less, or 1.2 or less, or 0.7 or less. The above TEOS film can be coated by plasma CVD method, reduced-pressure CVD method, sputtering method, or EB evaporation method.

Embodiments for Carrying out the Invention

[0014] The present invention contains silica particles, a basic nitrogen-containing organic compound, and water as a solvent, and the Rsp value represented by the following formula (1) calculated from the measurement value of pulsed NMR This is an abrasive composition in which the ratio exceeds 0.7 and is 6 or less. Rsp = (Rav - Rb) / (Rb) ... (1) However, Rsp is an indicator of water affinity, Rav is the reciprocal of the relaxation time of the polishing composition, and Rb is the reciprocal of the relaxation time of water, which is the solvent of the polishing composition. The above-mentioned silica particles are colloidal silica particles, with an average particle diameter of 12-200 nm or 20-150 nm as measured by dynamic light scattering, and the silica particles in the dispersion have an average primary particle diameter of 5-80 nm, 10-80 nm, or 15-70 nm as measured by nitrogen gas adsorption.

[0015] The measurement principle of this method (pulsed NMR) is based on the fact that solvent molecules in contact with or adsorbed on the particle surface and solvent molecules in the bulk solvent (solvent molecules in a free state not in contact with the particle surface) respond differently to changes in the magnetic field. Generally, the motion of liquid molecules adsorbed on the particle surface is restricted, while those in the bulk liquid can move freely. As a result, the NMR relaxation time of liquid molecules adsorbed on the particle surface is shorter than the relaxation time of molecules in the bulk liquid. Furthermore, the relaxation time measured in a particle dispersion is the average of two relaxation times: the liquid volume concentration on the particle surface and the liquid volume concentration in the free state (the liquid in the bulk liquid, but not adsorbed on the particle surface). Here, the relaxation time constant R is the reciprocal of the relaxation time. Rav=PsRs+PbRb It is determined by [method]. Rav: Mean relaxation time constant, i.e., the reciprocal of the relaxation time of a colloidal silica dispersion. Ps: This refers to the volume concentration of the liquid on the particle surface, i.e., the volume concentration of the colloidal silica dispersion. Rs: The relaxation time constant of the adsorbed phase liquid molecules on the particle surface, i.e., the reciprocal of the relaxation time of the colloidal silica dispersion. Pb: Volume concentration of the bulk liquid, i.e., the volume concentration of the blank aqueous solution from which silica particles have been removed in a colloidal silica dispersion. Rb: Relaxation time constant of bulk liquid molecules, i.e., the reciprocal of the relaxation time of a blank aqueous solution from which silica particles have been removed in a colloidal silica dispersion.

[0016] The Rsp value can be determined from the pulsed NMR measurement of the dispersion using the formula Rsp = (Rav - Rb) / (Rb). Rav and Rb are the reciprocals of the relaxation times (transverse relaxation time T2, specifically the NMR relaxation time after dispersion of silica abrasive particles and the NMR relaxation time before dispersion of silica abrasive particles (dispersion medium only)) measured using the Acorn area pulsed NMR spectrometer manufactured by Xigo nanotools (USA). The measurement conditions were: magnetic field: 0.3T, measurement frequency: 13MHz, measured nucleus: 1 ¹H NMR can be measured using the CPMG pulse sequencing method, with a sample volume of 0.4 mL and a temperature of 30°C. Rsp is an indicator of the water affinity of a particle surface. For the same specific surface area, a higher Rsp value indicates higher water affinity.

[0017] The basic nitrogen-containing organic compound used in the present invention is an aliphatic linear or cyclic amine which may contain a hydroxyl group, a carboxyl group, or a combination thereof, and the amine is a primary amine, a secondary amine, a tertiary amine, or a compound which is a combination thereof. The above amines may contain a hydroxyl group, a carboxyl group, or a combination thereof. They may also contain an aliphatic linear structure or an aliphatic cyclic structure. Furthermore, the structure may contain a primary amine, a secondary amine, a tertiary amine, or a combination thereof. The above amine preferably contains a secondary or tertiary linear aliphatic amine. The secondary structure and the tertiary structure may be contained individually in a single molecule, or both may be contained simultaneously. The above amine molecule contains a secondary or tertiary linear aliphatic amine, but may also contain a primary amine.

[0018] Examples of the basic nitrogen-containing organic compounds mentioned above include N-ethylethylenediamine, N-(2-hydroxyethyl)piperazine, triethylamine, and 2-aminoethanol, with N-ethylethylenediamine and triethylamine being particularly representative examples, but the compound is not limited to these. The basic nitrogen-containing organic compound described above preferably uses a low molecular weight amine with a molecular weight of 60 to 350, 60 to 150, or 80 to 110. These amines can be used individually or in combination. When using a mixture of multiple compounds, if they share the same solubility in water and basicity as the above-mentioned compounds, the following similar compounds or their salts (e.g., sulfates, hydrochlorides, nitrates) can be used in amounts of 50% by mass or less.

[0019] Examples of primary aliphatic amines include, but are not limited to, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert-butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, and tetraethylenepentamine. Examples of secondary aliphatic amines include, but are not limited to, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, N,N-dimethyltetraethylenepentamine, N-ethylethylenediamine, and N-(2-hydroxyethyl)piperazine. Examples of tertiary aliphatic amines include, but are not limited to, trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec-butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N,N,N',N'-tetramethylmethylenediamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'-tetramethyltetraethylenepentamine. Furthermore, examples of mixed amines include dimethylethylamine and methylethylpropylamine. Examples include, but are not limited to, benzylamine, phenethylamine, and benzyldimethylamine.

[0020] Examples of nitrogen-containing compounds having a carboxyl group include, but are not limited to, aminobenzoic acid, indolecarboxylic acid, and amino acid derivatives (e.g., nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, methoxyalanine).

[0021] Examples of nitrogen-containing compounds having a hydroxyl group, nitrogen-containing compounds having a hydroxyphenyl group, and alcoholic nitrogen-containing compounds include 2-aminoethanol, 2-hydroxypyridine, aminocresol, 2,4-quinoline diol, 3-indolemethanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N,N-diethylethanolamine, triisopropanolamine, 2,2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine, and 2-(2-hydroxyethyl) Examples include, but are not limited to, 1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidineethanol, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2-propanediol, 8-hydroxyeuroridine, 3-quinoclidinol, 3-tropanol, 1-methyl-2-pyrrolidineethanol, 1-aziridineethanol, N-(2-hydroxyethyl)phthalimide, and N-(2-hydroxyethyl)isonicotinamide.

[0022] The present invention contains an alkali metal hydroxide consisting of NaOH or KOH, or ammonia, and a basic nitrogen-containing organic compound, or a salt thereof, and can achieve an electrical conductivity of 100 to 650 μS / cm when the SiO2 concentration is 10% by mass.

[0023] In this invention, an acidic aqueous silica sol (with trace amounts of alkali metal ions remaining) is obtained by removing alkali ions from an alkaline aqueous silica sol stabilized with an alkali metal hydroxide, and the above-mentioned basic nitrogen-containing organic compound is added to it until the pH reaches 8 to 11. Therefore, the relationship (number of moles of basic nitrogen-containing organic compound or its salt) > (number of moles of alkali metal hydroxide consisting of NaOH or KOH, ammonia, or its salt) is obtained. Furthermore, an acid (hydrochloric acid, sulfuric acid, nitric acid, or phosphoric acid) is added to these alkaline silica sols, or an acidic silica sol with a pH of 1 to 6 is obtained by a combination of cation exchange and anion exchange. Therefore, it is preferable that the relationship (number of moles of basic nitrogen-containing organic compound or its salt) > (number of moles of alkali metal hydroxide consisting of NaOH or KOH, or ammonia or its salt), and that the electrical conductivity is 100 to 650 μS / cm when the SiO2 concentration is 10% by mass.

[0024] In the present invention, the polishing composition may further contain silica particles as abrasive grains and an aqueous medium, along with at least one additive selected from the group consisting of pH adjusters (alkaline components and water-soluble compounds), chelating agents, oxidizing agents, and metal corrosion inhibitors. The component (S) obtained by removing the aqueous medium from the abrasive composition is 0.01 to 20% by mass, or 0.1 to 10% by mass, the silica content in component (S) is 80 to 99.9% by mass, or 90 to 99.9% by mass, and the content of basic nitrogen-containing organic compounds in component (S) is 0.01 to 20% by mass, or 0.01 to 10% by mass.

[0025] Alkaline components include alkali metal hydroxides (sodium hydroxide, potassium hydroxide), ammonia, and amines. Amines exist in aqueous media in the form of their corresponding ammonium salts. The pH of the polishing composition of the present invention can be set to 1 to 12. By adding these alkaline components, the pH can be adjusted to a range of 7-12 or 8-11. Furthermore, the pH can be adjusted to a range of 1-7 or 1-6 by cation exchange or the addition of acids (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid).

[0026] Any water-soluble compound can be used as the water-soluble compound. For example, monomers having carboxylic acid groups such as acrylic acid, methacrylic acid, and maleic acid, and polymers thereof such as polyacrylic acid and polymethacrylic acid, and their salts such as ammonium polyacrylate, potassium polyacrylate, polyammonium polymethacrylate, and polypotassium polymethacrylate. In addition, alginic acid, pectic acid, carboxymethylcellulose, polyaspartic acid, polyglutamic acid, polyamic acid, ammonium polyamic acid, polyvinylpyrrolidone, hydroxyethylcellulose, glycerin, polyglycerin, polyvinyl alcohol, or polyvinyl alcohol modified with carboxyl or sulfonic acid groups can be used, but are not limited to these. Water-soluble compounds can be contained in a proportion of 0.01 to 10% by mass relative to the silica particles.

[0027] The chelating agent can be an aminocarboxylic acid-based chelating agent or a phosphonic acid-based chelating agent. The chelating resin can be contained in a ratio of 0.01 to 10% by mass relative to the silica particles. Examples of oxidizing agents include hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, and ozonated water. The oxidizing agent can be contained in a ratio of 0.01 to 10% by mass relative to the silica particles, but is not limited to these.

[0028] Examples of metal corrosion inhibitors include, but are not limited to, triazole compounds, pyridine compounds, pyrazole compounds, pyrimidine compounds, imidazole compounds, guanidine compounds, thiazole compounds, tetrazole compounds, triazine compounds, and hexamethylenetetramine. Triazole compounds include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole (BTA), 1-hydroxybenzotriazole, 1-hydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxy-1H-benzotriazole, 4-carboxy-1H-benzotriazole methyl ester (1H-benzotriazole-4-carboxylate methyl), 4-carboxy-1H-benzotriazole butyl ester (1H-benzotriazole-4-carboxylate butyl), 4-carboxy-1H-benzotriazole octyl ester (1H-benzotriazole-4-carboxylate octyl), 5-hexylbenzotriazole, (1,2,3-benzotriazolyl-1-methyl)(1,2,4-triazolyl-1- Methyl)(2-ethylhexyl)amine, tolyltriazol, naphthotriazol, bis[(1-benzotriazolyl)methyl]phosphonic acid, 3H-1,2,3-triazolo[4,5-b]pyridine-3-ol, 1H-1,2,3-triazolo[4,5-b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5-b]pyridine, 3-hydroxypyridine, 1,2,4-triazolo[1,5-a]pyrimidine, 1,3,4 Examples include, but are not limited to, 6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 2-methyl-5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, and 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine.

[0029] Examples of pyridine compounds include, but are not limited to, pyridine, 8-hydroxyquinoline, prothionamide, 2-nitropyridine-3-ol, pyridoxamine, nicotinamide, iproniazid, isonicotinic acid, benzo[f]quinoline, 2,5-pyridinedicarboxylic acid, 4-styrylpyridine, anabasine, 4-nitropyridine-1-oxide, pyridine-3-ethyl acetate, quinoline, 2-ethylpyridine, quinolinic acid, arecoline, citradilic acid, pyridine-3-methanol, 2-methyl-5-ethylpyridine, 2-fluoropyridine, pentafluoropyridine, 6-methylpyridine-3-ol, and pyridine-2-ethyl acetate.

[0030] Examples of pyrazole compounds include, but are not limited to, pyrazole, 1-allyl-3,5-dimethylpyrazole, 3,5-di(2-pyridyl)pyrazole, 3,5-diisopropylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3,5-dimethyl-1-phenylpyrazole, 3,5-dimethylpyrazole, 3-amino-5-hydroxypyrazole, 4-methylpyrazole, N-methylpyrazole, 3-aminopyrazole, and 3-aminopyrazole.

[0031] Examples of pyrimidine compounds include, but are not limited to, pyrimidines, 1,3-diphenylpyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxypyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, and 4-aminopyrazolo[3,4-d]pyrimidine.

[0032] Examples of imidazole compounds include, but are not limited to, imidazole, 1,1'-carbonylbis-1H-imidazole, 1,1'-oxalyldiimidazole, 1,2,4,5-tetramethylimidazole, 1,2-dimethyl-5-nitroimidazole, 1,2-dimethylimidazole, 1-(3-aminopropyl)imidazole, 1-butylimidazole, 1-ethylimidazole, 1-methylimidazole, and benzimidazole.

[0033] Examples of guanidine compounds include, but are not limited to, guanidine, 1,1,3,3-tetramethylguanidine, 1,2,3-triphenylguanidine, 1,3-di-o-tolylguanidine, and 1,3-diphenylguanidine.

[0034] Examples of thiazole compounds include, but are not limited to, thiazole, 2-mercaptobenzothiazole, and 2,4-dimethylthiazole. Examples of tetrazole compounds include, but are not limited to, tetrazole, 5-methyltetrazole, 5-amino-1H-tetrazole, and 1-(2-dimethylaminoethyl)-5-mercaptotetrazole.

[0035] Examples of triazine compounds include, but are not limited to, triazine and 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine. The metal corrosion inhibitor can be added in a ratio of 0.0001 to 10% by mass relative to the silica particles.

[0036] The silica used in the present invention can be used to produce an abrasive composition by a method comprising (A) mixing a silica sol obtained by any one of the following methods (a) to (d) with the above-mentioned basic nitrogen-containing organic compound, or by a method comprising dispersing the silica sol and the above-mentioned basic nitrogen-containing organic compound in an aqueous medium (B). Method (A) involves mixing a silica source (silica sol, or an abrasive composition containing silica sol) with a basic nitrogen-containing organic compound. Method (B) involves dispersing the silica source and the basic nitrogen-containing organic compound in an aqueous medium. In this case, there are two methods: adding the silica source as silica sol (B1), or converting the silica sol into silica powder and then dispersing it in the aqueous medium (B2). The silica source can be produced using any one of the following methods: (a) to (d). (a) Step: A process to obtain silica sol by heat-treating an activated silica aqueous solution obtained by ion-exchange of sodium silicate aqueous solution. (b) Step: Step to obtain silica sol by hydrolysis of alkoxysilane. (c) Step: A step to obtain silica sol by wet grinding of silica powder in an aqueous medium. (d) Step: A step to obtain silica sol by dispersing silica powder obtained by combustion hydrolysis of silicon tetrachloride in a flame in an aqueous medium. (a) The process can be broadly divided into three steps: (aI) obtaining activated silicic acid, (a-II) heating and sizing the activated silicic acid, and (a-III) adjusting the concentration of the obtained silica sol.

[0037] The process of obtaining activated silicic acid (aI) is divided into the process of obtaining activated silicic acid (aI), the process of purifying it to a high degree (aII), and the process of recovering the purified activated silicic acid (a-I-II). (a-1) is mandatory, while (aII) and (a-I-II) are optional processes. For example, step (aI): This step involves contacting an aqueous solution of an alkali metal silicate containing a metal oxide other than silica in a ratio of 300 to 500,000 ppm relative to silica, with a hydrogen-type strongly acidic cation exchange resin to produce an aqueous solution of activated silica with an SiO2 concentration of 1 to 6% by mass, where the alkali metal silicate is dissolved at a concentration of 0.5 to 10.0% by mass or 1 to 6% by weight as the SiO2 content derived from this silicate. The resulting solution is then collected.

[0038] The process of heating and granulating the activated silicic acid (a-II) includes the following steps (a-II-I) and (a-II-II). (a-II-I) Step: Add an aqueous solution of alkali metal hydroxide or ammonia to the aqueous solution of activated silicic acid recovered in step (aI) to produce a stabilized aqueous solution of activated silicic acid having an SiO2 concentration of 0.5 to 10.0% by mass, or 1 to 6% by mass, and a pH of 7 to 9. (a-II-II) Step: An alkali metal silicate aqueous solution, ammonia silicate aqueous solution obtained by adding an alkali metal hydroxide or ammonia hydroxide aqueous solution to the aqueous solution of activated silicic acid recovered in Step (a-II-I), or an alkali metal silicate aqueous solution or ammonia silicate aqueous solution having a pH of 10-12.5 and an SiO2 concentration of 0.1-8% by mass, obtained by concentrating or diluting this aqueous solution, or an aqueous solution of activated silicic acid obtained in the same manner as in Step (a-II-I), is supplied over a period of 1-30 hours under sufficient stirring while maintaining the temperature of the resulting mixture at 110-150°C, or 110-145°C, or 110-140°C, or 110-135°C, until the pH of the mixture reaches 9-12.

[0039] The step (a-III) for adjusting the concentration of the obtained silica sol involves concentrating the silica sol to 10-50% by mass, and impurities can be removed before and after concentration. This step (a-III) is not mandatory but can be performed if desired. Then, step (a-IV): After contacting the stable aqueous silica sol obtained in step (a-III) with a hydrogen-type strongly acidic cation exchange resin, the aqueous silica sol produced by this contact is contacted with a hydroxyl-group type strongly basic anion exchange resin to produce an acidic aqueous silica sol that is substantially free of polyvalent metal oxides other than silica. (aV) Step: This step involves adding alkali to the acidic aqueous sol produced in Step (a-IV) so that the pH of the sol becomes 8-11, thereby producing a stable aqueous silica sol having an SiO2 concentration of 10-50% by mass or 30-50% by mass, substantially free of polyvalent metal oxides other than silica, and having an average particle size of colloidal silica of 10-30 nm.

[0040] In step (aI) above, it is preferable to use sodium aqueous glass, an inexpensive industrial product with an SiO2 / Na2O molar ratio of about 2 to 4. The main impurities that are relatively high in polyvalent metals are aluminum, iron, calcium, magnesium, etc. The alkali metal silicate aqueous solution is brought into contact with the hydrogen-type strong acid cation exchange resin. This contact can preferably be carried out by passing the solution through a column packed with this ion exchange resin, and the liquid that passes through the column is recovered as an aqueous solution of activated silicic acid with an SiO2 concentration of 1 to 6% by mass, preferably 2 to 6% by mass. The amount of hydrogen-type cation exchange resin used should be sufficient to exchange all of the alkali metal ions in the alkali metal silicate aqueous solution with hydrogen ions. The rate at which the solution passes through the column is preferably a space velocity of about 1 to 10 per hour.

[0041] (aII) Examples of strong acids used in step (aII) include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid, but nitric acid is most preferred for increasing the removal rate of aluminum and iron. In step (aI-II), the aqueous solution obtained in step (aII) is first brought into contact with the hydrogen-type strongly acidic cation exchange resin. This contact can preferably be carried out by passing the aqueous solution through a column packed with the hydrogen-type strongly acidic cation exchange resin at a space velocity of 2 to 20 per hour at 0 to 60°C, preferably 5 to 50°C. Next, the aqueous solution obtained by this contact is preferably brought into contact with the hydroxyl-type strongly basic anion exchange resin immediately after it is obtained at 0 to 60°C, preferably 5 to 50°C.

[0042] (a-II) The aqueous solution of alkali hydroxide used in step (a-II) is preferably obtained by dissolving commercially available industrial alkali hydroxide with a component concentration of 95% or more in ion-exchanged water to a concentration of preferably 2 to 20% by mass. (a-III) The apparatus used in the process may be a standard container that is resistant to acids, alkalis, and pressure, and is equipped with a stirrer, a temperature control device, a liquid level sensor, a depressurization device, a liquid supply device, the above-mentioned cooling device, etc. (a-III) In step (a-III), the liquid temperature inside the container is maintained at less than 110-150°C.

[0043] The contact between the stable aqueous sol and the ion exchange resin in step (a-IV) can be carried out in the same manner as the contact in step (aI). The alkali used in step (aV) may be a commercially available industrial product, but a high-purity one is preferred, and in the case of ammonia, it is preferable to use it as aqueous ammonia at a concentration of 5 to 28% by mass. Instead of ammonia, quaternary ammonium hydroxide, guanidine hydroxide, water-soluble amines, etc., can also be used. Potassium hydroxide can be suitably used in the present invention.

[0044] As a silica source for step (b) of the present invention, silica sol obtained by hydrolysis of alkoxysilane can be used. Hydrolysis is carried out by adding alkoxysilane to an organic solvent (methanol) containing a catalyst and water. Tetramethoxysilane and tetraethoxysilane can be used as alkoxysilanes. Ammonia and alkali metal hydroxides can be used as catalysts, but ammonia is used as a volatile catalyst to achieve high purity. As a method for step (c) of the present invention, silica powder can be produced by wet grinding in an aqueous medium. To distinguish it from the raw materials of step (d) below, silica powder made by grinding natural silica sand or the like can be used as the silica powder. Acids or alkalis can be added during wet grinding. For wet grinding, it is preferable to grind the material using a ball mill, colloid mill, sand mill, or disperser until the primary particle size reaches the colloidal region suitable for use as a silica source in the present invention, and then disperse it in an aqueous medium.

[0045] As a method for step (d) of the present invention, silica is obtained by wet grinding of silica obtained by combustion hydrolysis of silicon tetrachloride in a flame. Acids or alkalis can be added during wet grinding. For wet grinding, it is preferable to grind the silica using a ball mill, colloid mill, sand mill, or disperser, etc., until the primary particle size reaches the colloid region suitable for use as a silica source in the present invention, and then disperse it in an aqueous medium. According to the present invention, when a basic nitrogen-containing organic compound is added to a silica source (silica sol, or a polishing composition containing silica sol), it is preferable that the rate of change in the average particle size of the silica source measured by dynamic light scattering is within 20% or 15% of the value before the addition.

[0046] In step (a) above, the aqueous sodium silicate solution and / or activated silicic acid solution used may be one that has been filtered in advance. A filter is provided in which the silica concentration of an aqueous sodium silicate solution is adjusted to 0.5-10.0% by mass, and the removal rate of particles with a primary particle diameter of 1.0 μm is 50% or more, or 60% or more, or 80% or more, with a filtration area of ​​1 m². 2 It can be filtered with a filter having a filtration rate of 13 liters / minute to 400 liters / minute.

[0047] Furthermore, an activated silica aqueous solution is prepared by removing alkaline components from a sodium silicate aqueous solution adjusted to a silica concentration of 0.5% to 10.0% by mass through cation exchange, and this activated silica aqueous solution is used in a filter with a filtration area of ​​1 m², having a removal rate of 50% or more, or 60% or more, or 80% or more of particles with a primary particle diameter of 1.0 μm. 2 It can be filtered with a filter having a filtration rate of 13 liters / minute to 400 liters / minute. In the semiconductor device planarization process, a polishing step using an abrasive containing colloidal silica is followed by the removal of colloidal silica abrasive grains and fine particles by washing. Spherical particles are easily removed by washing after polishing, but plate-shaped particles are difficult to remove even with washing after polishing. The particles to be removed by the above filter are mainly plate-shaped fine silica particles present in the sodium silicate aqueous solution and the activated silicic acid aqueous solution used as raw materials in the silica sol manufacturing process.

[0048] A silica sol is manufactured and then prepared into an abrasive composition. It is preferable to remove coarse particles (mainly silica) that may cause defects during polishing in advance during the silica sol manufacturing process. Examples of the filters mentioned above include membrane filters, pleated filters, depth filters, wound filters, surface filters, roll filters, depth-pleated filters, and diatomaceous earth-containing filters. Preferably, the filter is a membrane filter with an absolute pore size of 0.3 to 3.0 μm.

[0049] The above removal rate was measured by, for example, using 30 mL of a sodium silicate aqueous solution or activated silicic acid aqueous solution adjusted to a silica concentration of 4% by mass at 25°C, and filtering it through a membrane-type filter with an absolute pore size of 0.4 μm (filtration area 4.90 cm²). 2After filtering with ), the membrane-type filter is observed under a scanning electron microscope at 5000x magnification. A rectangular observation area of ​​15 μm vertically and 20 μm horizontally is defined as one field of view. If one or more flat, plate-shaped microparticles are present in this field of view, one count is determined. The presence or absence of counts is determined for all 100 non-overlapping fields of view, and the total number of counts obtained is taken as the percentage of flat, plate-shaped microparticles present. The polishing composition of the present invention can be used for polishing semiconductor wafers, semiconductor devices (device wafers), and Si-containing substrates such as quartz substrates.

[0050] The polishing method used for semiconductor devices is CMP (Chemical Mechanical Polishing), which can be applied to the formation of wiring on semiconductor substrates. Examples of materials that can be polished include conductive material layers (wiring layers), barrier layers (layers composed of barrier metals, such as titanium nitride and tantalum nitride to prevent copper from diffusing into the insulating layer), and insulating layers (layers composed of interlayer insulating materials, such as low-k materials, such as SiO2, SiOC, and porous silica). More specifically, the materials constituting the conductive material layer include, but are not limited to, copper-based metals such as copper, copper alloys, copper oxides, and oxides of copper alloys; tungsten-based metals such as tungsten, tungsten nitride, and tungsten alloys; cobalt-based metals such as cobalt, cobalt alloys, cobalt oxides, and oxides of cobalt alloys; silver; and gold. Among these, at least one copper-based metal selected from the group consisting of copper, copper alloys, copper oxides, and oxides of copper alloys is preferred, with copper being more preferred. The conductive material can be formed by known sputtering methods, plating methods, etc.

[0051] The barrier metal constituting the barrier layer is formed to prevent the diffusion of conductive material into the insulating material and to improve the adhesion between the insulating material and the conductive material. The barrier metal material constituting the barrier metal is preferably at least one selected from the group consisting of tantalum-based metals, titanium-based metals, tungsten-based metals, ruthenium-based metals, cobalt-based metals, and manganese-based metals. Specifically, examples include, but are not limited to, tantalum-based metals such as tantalum, tantalum nitride, and tantalum alloys; titanium-based metals such as titanium, titanium nitride, and titanium alloys; tungsten-based metals such as tungsten and tungsten alloys; ruthenium-based metals such as ruthenium and ruthenium alloys; cobalt-based metals such as cobalt and cobalt alloys; and manganese-based metals such as manganese and manganese alloys. Examples of constituent materials for insulating materials include, but are not limited to, silicon-based materials and organic polymers. The insulating material may also be in the form of a film (insulating film, e.g., interlayer insulating film). Examples of insulating films include, but are not limited to, silicon-based coatings and organic polymer films. The insulating film can be formed by methods such as CVD, spin coating, dip coating, and spray coating. Examples of silicon-based materials include silica-based materials and low-k materials (low dielectric constant materials). Examples of silica-based materials include silicon dioxide; fluorosilicate glass; organosilicate glass obtained from trimethylsilane or dimethoxydimethylsilane as starting materials; porous organosilicate glass; silicon oxynitride; and hydrogenated silsesquioxane. Examples of low-k materials include silicon carbide and silicon nitride, but are not limited to these.

[0052] The polishing method according to the present invention involves, for example, forming a conductive thin film made of a conductive material on a silicon substrate, forming a resist film on top of it, and exposing and developing the resist layer using a circuit pattern as a mask by lithography to transfer the pattern to the resist layer. Using the transferred pattern as a mask, the conductive film is dry-etched with a highly anisotropic ionic gas. Examples of gases that can be used include, but are not limited to, tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride and chlorine trifluoride, chlorine, trichloroborane and dichloroborane. Furthermore, the resist film is ashing with oxygen gas to remove the resist layer. This removal of the resist layer can also be done using chemical solutions (for example, a mixture of sulfuric acid and hydrogen peroxide, or a mixture of ammonia and hydrogen peroxide) to protect the substrate.

[0053] Subsequently, an insulating film is deposited to prevent short circuits with the upper layer wiring. The wafer surface on which this interlayer insulating film is deposited reflects the pattern of the lower layer wiring, resulting in various sizes of irregularities in the insulating film. When a resist film is applied to the upper layer and wiring is processed by lithography in this state, diffuse reflection occurs at the interface between the resist and the insulating film during exposure of the resist, preventing the formation of a rectangular resist pattern and making it difficult to process the lower layer surface. Therefore, the wafer surface is planarized. This planarization of the interlayer insulating film is performed by CMP (Chemical Polishing). Furthermore, while aluminum has traditionally been used as the wiring material, its low melting point has led to reliability issues such as disconnection when high currents flow, and there has been a shift from aluminum wiring to copper wiring. However, the diffusion of copper into the insulating layer is a problem. Therefore, in the damascene process, grooves called damascene are formed before embedding the copper, but a barrier layer is also formed between the copper and the insulating layer to prevent the diffusion of copper into the insulating layer. The unevenness of the copper resulting from the embedding of copper for the formation of the copper wiring layer requires flattening of the copper wiring layer surface for lithography of the upper layer, and flattening of copper is difficult with gas dry etching due to its hardness, so polishing by CMP is performed. [Examples]

[0054] ( reference Example 1) Silica sol 1 (manufactured by Nissan Chemical Corporation, average primary particle size 20 nm by BET (nitrogen gas adsorption method), average particle size 32.2 nm by DLS (dynamic light scattering method), SiO2 concentration 25.5% by mass, Na2O / SiO2 = 3000 ppm, pH 10), which was adjusted to alkalinity with potassium hydroxide, was filtered through a 0.3 μm cartridge filter and converted to acidic silica sol by ion exchange. Then, pure water and a basic nitrogen-containing organic compound (N-ethylethylenediamine) were added to obtain a polishing composition with an SiO2 concentration of 10% by mass and a pH of 10. reference The SiO2 content in component (S) of the polishing composition of Example 1, excluding the aqueous medium, was 98.2% by mass, and the content of the basic nitrogen-containing organic compound was 1.8% by mass. reference In Example 1, the average primary particle size measured by the BET method in the polishing composition was 20 nm, and the average particle size measured by the DLS method was 31.9 nm.

[0055] ( Reference example 2, Examples 3 ~4) Except for the change in the basic nitrogen-containing organic compound to that listed in Table 1, reference The polishing composition was obtained by following the same procedure as in Example 1. referenceIn Example 2, the SiO2 content in component (S) after removing the aqueous medium was 93.7% by mass, and the content of the basic nitrogen-containing organic compound was 6.3% by mass. In Example 3, the SiO2 content in component (S) after removing the aqueous medium was 97.7% by mass, and the content of the basic nitrogen-containing organic compound was 2.3% by mass. In Example 4, the SiO2 content in component (S) after removing the aqueous medium was 97.9% by mass, and the content of the basic nitrogen-containing organic compound was 2.1% by mass. After adding a basic nitrogen-containing organic compound reference In Example 2, the average primary particle size measured by BET was 20 nm, and the average particle size measured by DLS was 31.7 nm. In Example 3, after the addition of a basic nitrogen-containing organic compound, the average primary particle size measured by BET was 20 nm, and the average particle size measured by DLS was 31.5 nm. In Example 4, after the addition of a basic nitrogen-containing organic compound, the average primary particle size measured by BET was 20 nm, and the average particle size measured by DLS was 31.8 nm.

[0056] ( reference Example 5) Silica sol 2 (manufactured by Nissan Chemical Corporation, with an average primary particle diameter of 20 nm by BET (nitrogen gas adsorption method) and an average particle diameter of 29.2 nm by DLS (dynamic light scattering method), an SiO2 concentration of 41% by mass, Na2O / SiO2 = 50 ppm, and pH 10) was filtered through a 0.3 μm cartridge filter, acidified by ion exchange, and then pure water and a basic nitrogen-containing organic compound were added to obtain a polishing composition with an SiO2 concentration of 10% by mass and pH 10. reference In the polishing composition of Example 5, the SiO2 content in component (S), excluding the aqueous medium, was 96.4% by mass, and the content of basic nitrogen-containing organic compounds was 3.6% by mass. After adding a basic nitrogen-containing organic compound reference In Example 5, the average primary particle size measured by the BET method in the polishing composition was 20 nm, and the average particle size measured by the DLS method was 32.5 nm.

[0057] ( Reference example 6, Examples 7 ~8) Except for the change in the basic nitrogen-containing organic compound to that listed in Table 1, reference The polishing composition was obtained by following the same procedure as in Example 5. reference In Example 6, the SiO2 content in component (S) after removing the aqueous medium was 91.5% by mass, and the content of the basic nitrogen-containing organic compound was 8.5% by mass. In Example 7, the SiO2 content in component (S) after removing the aqueous medium was 97.8% by mass, and the content of the basic nitrogen-containing organic compound was 2.2% by mass. In Example 8, the SiO2 content in component (S) after removing the aqueous medium was 97.7% by mass, and the content of the basic nitrogen-containing organic compound was 2.3% by mass. After adding a basic nitrogen-containing organic compound reference Mean first order of the BET method in the polishing composition of Example 6 The particle size was 20 nm, and the average particle size by the DLS method was 30.0 nm. In the polishing composition of Example 7 after the addition of a basic nitrogen-containing organic compound, the average primary particle size by the BET method was 20 nm, and the average particle size by the DLS method was 29.8 nm. In the polishing composition of Example 8 after the addition of a basic nitrogen-containing organic compound, the average primary particle size by the BET method was 20 nm, and the average particle size by the DLS method was 29.2 nm.

[0058] ( reference Example 9) Silica sol 3 (manufactured by Fuso Chemical Industries, Ltd., average primary particle size 17 nm by BET (nitrogen gas adsorption method), average particle size 26.8 nm by DLS (dynamic light scattering method), SiO2 concentration 19.5% by mass, Na2O / SiO2 = 350 ppb), filtered through a cartridge filter with a pore size of 3 μm, was mixed with pure water and a basic nitrogen-containing organic compound to prepare a polishing composition with an SiO2 concentration of 10% by mass and a pH of 10. reference In the polishing composition of Example 9, the SiO2 content in component (S), excluding the aqueous medium, was 97.9% by mass, and the content of basic nitrogen-containing organic compounds was 2.1% by mass. After adding a basic nitrogen-containing organic compound reference In Example 9, the average primary particle size measured by the BET method in the polishing composition was 17 nm, and the average particle size measured by the DLS method was 27.4 nm.

[0059] ( reference Example 10) Except for the change in the basic nitrogen-containing organic compound to that listed in Table 1, reference The polishing composition was obtained by following the same procedure as in Example 9. reference In the polishing composition of Example 10, the SiO2 content in component (S), excluding the aqueous medium, was 97.6% by mass, and the content of basic nitrogen-containing organic compounds was 2.4% by mass. After adding a basic nitrogen-containing organic compound reference In the polishing composition of Example 10, the average primary particle size measured by BET was 17 nm, and the average particle size measured by DLS was 27.1 nm.

[0060] (Comparative Example 1) Silica sol 1 (manufactured by Nissan Chemical Corporation, average primary particle size 20 nm by BET (nitrogen gas adsorption method), average particle size 32.2 nm by DLS (dynamic light scattering method), SiO2 concentration 25.5% by mass, Na2O / SiO2 = 3000 ppm, pH 10), which was adjusted to alkalinity with potassium hydroxide, was filtered through a 0.3 μm cartridge filter to obtain a polishing composition.

[0061] (Comparative Example 2) A polishing composition was obtained by filtering silica sol 2 (manufactured by Nissan Chemical Corporation, with an average primary particle size of 20 nm by the BET (nitrogen gas adsorption) method, an average particle size of 29.2 nm by the DLS (dynamic light scattering) method, an SiO2 concentration of 41% by mass, Na2O / SiO2 = 50 ppm, and pH 10) through a 0.3 μm cartridge filter.

[0062] (Comparative Example 3) Silica sol 3 (manufactured by Fuso Chemical Industries, Ltd., average primary particle size 17 nm by BET (nitrogen gas adsorption method), average particle size 26.8 nm by DLS (dynamic light scattering method), SiO2 concentration 19.5% by mass, Na2O / SiO2 = 350 ppb), filtered through a cartridge filter with a pore size of 3 μm, was used as the polishing composition.

[0063] [Table 1]

[0064] (Pulsed NMR measurement) Examples , reference example The transverse relaxation times of each polishing composition in the comparative examples were measured using a pulsed NMR spectrometer, Acorn area, manufactured by Xigo nanotools. The measurement conditions were: magnetic field: 0.3T, measurement frequency: 13MHz, measurement nucleus: 1 ¹H NMR was performed using the CPMG pulse sequencing method, with a sample volume of 0.4 ml and a temperature of 30°C. The lateral relaxation time of the blank solution was measured using pure water. Rav was defined as the reciprocal of the relaxation time for each polishing composition, and Rb as the reciprocal of the relaxation time for the blank solution. Rsp was then calculated using the formula Rsp = (Rav - Rb) / Rb.

[0065] (LPC measurement) Examples , reference example The number of particles larger than 0.16 μm contained in each of the comparative abrasive compositions was measured using Accusizer® FXnano (manufactured by Particle Sizing Systems, Inc., USA). The polishing conditions and cleaning methods were as follows.

[0066] (Measuring pH) Measurements were taken using a multi-purpose water quality meter (manufactured by Toa DKK Corporation, model number: MM-60R) and a pH composite electrode (manufactured by Toa DKK Corporation, model number: GST-5741C).

[0067] (Electrical conductivity) The measurements were taken using an electrical conductivity meter (Toa DKK Corporation, model number: CM-30R) and an electrical conductivity cell (Toa DKK Corporation, model number: CT57101B). (Measurement of average particle diameter using dynamic light scattering method) The measurements were performed using a particle size, zeta potential, and molecular weight analyzer (Malvern Zetasizer Nano ZS).

[0068] (polishing conditions) Polishing machine: ChaMP332 (for 12-inch) manufactured by Tokyo Seimitsu Co., Ltd. Processing pressure: 1.7 psi Plate rotation speed: 90 rpm Head rotation speed: 90 rpm Polishing pad: Nitta & Haas IC1400XY + Perforate Dresser: 3M A2865 (#80 diamond) Polishing diluent supply rate: 300 mL / min Polishing time: 60sec Substrate: TEOS film-coated wafer

[0069] (Washing conditions) The cleaning was performed using a chemical brush, starting with an acidic chemical solution, followed by a rinse with pure water, and then drying. (Measurement of defects) The number of defects was measured using a Hitachi LS6700, focusing on the number of defects with a wavelength of 180 nm or larger.

[0070] [Table 2] In Table 2, Rsp represents the Rsp value calculated from pulsed NMR measurements, LPC represents the count number of coarse particles 0.16 μm or larger (particles / mL) contained in the polishing composition, the defect count represents the number of defects 180 nm or larger per unit polished surface, pH represents the adjusted pH value of the polishing composition, electrical conductivity represents the electrical conductivity (μS / cm) when the SiO2 concentration of the polishing composition is 10 mass%, and the DLS change rate represents the percentage change (%) in the average particle size (nm) by dynamic light scattering method compared to before the addition of a basic nitrogen-containing organic compound. Examples of the present invention 3, 4, 7 and 8 In a polishing composition containing silica particles and a basic nitrogen-containing organic compound, the Rsp value of the pulsed NMR has a specific numerical range, which suppresses the occurrence of defects when used as a polishing composition for CMP polishing of device wafers. Furthermore, examples... 7 In the ~8 range, despite an increase in LPC values, an unexpected effect was observed: a reduction in defects. Furthermore, despite high Rsp values ​​indicating affinity in Comparative Examples 1 and 3, the occurrence of defects was not suppressed. [Industrial applicability]

[0071] The polishing composition of the present invention can be used not only for polishing device wafers for CMP (Chemical Polishing), but also as a polishing agent for silicon wafers and for quartz substrates for photomasks. Regardless of the above-mentioned applications, the present invention can be used to polish metals or metalloids such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, and stainless steel, or their alloys; glassy materials such as quartz glass, aluminosilicate glass, and glassy carbon; ceramic materials such as alumina, silica, sapphire, silicon nitride, tantalum nitride, and titanium carbide; compound semiconductor substrate materials such as silicon carbide, gallium nitride, and gallium arsenide; and resin materials such as polyimide resin. Furthermore, it is also applicable to polishing objects composed of multiple of these materials.

Claims

1. An abrasive composition comprising silica particles, a basic nitrogen-containing organic compound, and water as a solvent, wherein the Rsp value, calculated from pulse NMR measurements using the following formula (1), is greater than 0.7 and less than or equal to 1.4, The basic nitrogen-containing organic compound is an aliphatic linear amine. The aliphatic linear amine is 2-aminoethanol or triethylamine. SiO ２ An abrasive composition having an electrical conductivity of 270 μS / cm or more and 650 μS / cm or less at a concentration of 10% by mass. Rsp=(Rav-Rb) / (Rb)...(1) (In formula (1), Rsp is an index indicating water affinity, Rav is the reciprocal of the relaxation time of the polishing composition, and Rb is the reciprocal of the relaxation time of water, which is the solvent of the polishing composition.)

2. The polishing composition according to claim 1, wherein the average primary particle diameter of silica particles measured by nitrogen gas adsorption is 5 to 80 nm, and the average particle diameter of silica particles measured by dynamic light scattering is 12 to 200 nm.

3. The polishing composition according to claim 1 or claim 2, comprising an alkali metal hydroxide consisting of NaOH or KOH or ammonia, and a basic nitrogen-containing organic compound, or a salt thereof, wherein (number of moles of basic nitrogen-containing organic compound or salt thereof) > (number of moles of alkali metal hydroxide consisting of NaOH or KOH or ammonia or salt thereof).

4. The polishing composition according to any one of claims 1 to 3, further comprising a pH adjuster consisting of an inorganic acid, an organic acid, an alkali metal hydroxide, an ammonium salt, ammonia, or a combination thereof.

5. The polishing composition according to any one of claims 1 to 4 further comprises an aminocarboxylic acid-based chelating agent, a phosphonic acid-based chelating agent, or a chelating agent consisting of a combination thereof. 。

6. The polishing composition according to any one of claims 1 to 5, wherein the pH is 1 to 12.

7. A polishing composition according to any one of claims 1 to 6, for use in polishing silicon wafers, device wafers, or Si-containing substrates.

8. A method for producing an abrasive composition according to any one of claims 1 to 7, comprising: (A) a method of mixing a silica sol obtained by any one of the following steps (a) to (d) with the basic nitrogen-containing organic compound; or (B) a method of dispersing the silica sol and the basic nitrogen-containing organic compound in an aqueous medium. (a) Step: A process in which an aqueous sodium silicate solution is subjected to ion exchange, and the resulting activated silica solution is heat-treated to obtain silica sol. (b) Step: Step to obtain silica sol by hydrolysis of alkoxysilane. (c) Step: A step to obtain silica sol by wet grinding of silica powder in an aqueous medium. (d) Step: A step to obtain silica sol by dispersing silica powder obtained by combustion hydrolysis of silicon tetrachloride in a flame in an aqueous medium.

9. (a) The method for producing the polishing composition according to claim 8, wherein the aqueous sodium silicate solution and / or activated silicate solution used in step (a) have been filtered in advance.

10. A method for producing an abrasive composition according to claim 8 or claim 9, wherein the rate of change in the average particle size measured by dynamic light scattering before and after the addition of a basic nitrogen-containing organic compound is less than 20%.

11. A polishing method for polishing a TEOS film-coated wafer for 60 seconds using the polishing composition described in any one of claims 1 to 7, thereby reducing the number of defects of 180 nm or more per square centimeter to 1.4 or less.

12. The polishing method according to claim 11, wherein the TEOS film-coated wafer is a 300 mm wafer.

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