JP2015189965A - Composition for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for polishing suitable for the polishing of the object to be polished having a layer including metal and capable of making the surface roughness of the layer including metal satisfactory.SOLUTION: Provided is a composition for polishing comprising abrasives and an oxidizer, and in which the value of the average association degree of the abrasives is below 5.0. Preferably, the abrasives is colloidal silica. Preferably, the value of the aspect ratio of the abrasives is below 2.0. Preferably, the value of the D90/D10 of the abrasives is 2.04 or lower. Preferably, the composition for polishing is used for the application of polishing the object to be polished having a layer including metal.

Description

  The present invention relates to a polishing composition.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of LSIs. Chemical mechanical polishing (hereinafter also simply referred to as CMP) is one of them, and is frequently used in LSI manufacturing processes, particularly in the formation of interlayer insulating films, metal plugs, and embedded wiring (damascene wiring) in the multilayer wiring forming process. The technology used.

A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the polishing pad surface with an abrasive, press the surface on which the metal film of the substrate is formed, A polishing platen is turned in a state where pressure (hereinafter also simply referred to as polishing pressure) is applied, and the metal film is removed by mechanical friction between the abrasive and the metal film.
As these metal films, tungsten or an alloy thereof is frequently used.

  In general, a tungsten plug and a tungsten wiring in a semiconductor device are formed by forming a conductor layer made of tungsten or a tungsten alloy on an insulator layer made of silicon oxide in which a recess is formed, and then forming a conductor layer on the insulator layer. This is done by removing a portion by polishing until the insulator layer is exposed. This polishing process is roughly divided into a main polishing process for performing polishing for removing most of the conductor layer to be removed, and a buff polishing process for final polishing of the conductor layer and the insulator layer.

  A polishing composition used in a semiconductor device manufacturing process generally includes a polishing accelerator such as an acid, an oxidizing agent, and abrasive grains. For example, Patent Document 1 uses a polishing slurry that is used in chemical mechanical polishing in a semiconductor device manufacturing process and includes fumed silica and a solvent, and the solvent is an oxidizing water of ultrapure water. There is a disclosure of a technique for polishing tungsten.

JP 2000-340532 A

  However, when the polishing composition of Patent Document 1 is used in a process for forming a tungsten plug or a tungsten wiring, particularly in a buff polishing step in the same process, it has been confirmed that the polished surface of tungsten is roughened.

  Then, this invention is suitable for grinding | polishing the grinding | polishing target object which has a layer containing a metal, and it aims at providing the polishing composition which can make the surface roughness of the layer containing a metal favorable.

  In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, it was found that the degree of association of the abrasive grains is related to the surface roughness of the layer containing the metal, and the above problem can be solved by reducing the average degree of association of the abrasive grains, that is, approaching a perfect circle. I found it. And based on the said knowledge, it came to complete this invention.

  That is, the present invention is a polishing composition containing abrasive grains and an oxidizing agent, and having an average degree of association of the abrasive grains of less than 5.0.

  ADVANTAGE OF THE INVENTION According to this invention, it is suitable for grinding | polishing of the grinding | polishing target object which has a layer containing a metal, and the polishing composition which can make the surface roughness of the layer containing a metal favorable can be provided.

  The present invention is a polishing composition comprising abrasive grains and an oxidizing agent, wherein the average degree of association of the abrasive grains is less than 5.0. By setting it as such a structure, it is suitable for grinding | polishing of the grinding | polishing target object which has a layer containing a metal, and the surface roughness of the layer containing a metal can be made favorable.

The detailed reason why the above-described effects can be obtained by using the polishing composition of the present invention is not clear, but is considered to be due to the following mechanism.
The layer containing a metal is oxidized by an oxidizing agent to form an oxide film. This film is polished by being scraped by abrasive grains. In this scraping, if the average degree of association of the abrasive grains is low, that is, if the shape is close to a perfect circle, the abrasive traces due to scraping are small, and after polishing the oxide film, the polished surface is not roughened. . In addition, the said mechanism is based on estimation and this invention is not limited to the said mechanism at all.

[Polishing object]
The polishing object according to the present invention has a layer containing a metal.

  The metal is not particularly limited, and examples thereof include tungsten, copper, aluminum, hafnium, cobalt, nickel, titanium, tantalum, titanium, cobalt, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, and osmium. . These metals may be contained in the form of an alloy or a metal compound. Tungsten is preferable. These metals may be used alone or in combination of two or more.

  Next, the structure of the polishing composition of the present invention will be described in detail.

[Abrasive grain]
The polishing composition of the present invention essentially contains abrasive grains as a characteristic component. The abrasive grains contained in the polishing composition have an action of mechanically polishing the object to be polished, and improve the polishing rate of the object to be polished by the polishing composition.

  The abrasive used may be any of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include particles made of metal oxides such as silica, alumina, ceria, titania, silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. These abrasive grains may be used alone or in combination of two or more. The abrasive grains may be commercially available products or synthetic products.

  Among these abrasive grains, silica is preferable, and colloidal silica is particularly preferable.

  The abrasive grains may be surface-modified. Since ordinary colloidal silica has a zeta potential value close to zero under acidic conditions, silica particles are not electrically repelled with each other under acidic conditions and are likely to agglomerate. On the other hand, abrasive grains whose surfaces are modified so that the zeta potential has a relatively large negative value even under acidic conditions are strongly repelled from each other and dispersed well even under acidic conditions, resulting in storage of the polishing composition. Stability will be improved. Such surface-modified abrasive grains can be obtained, for example, by mixing a metal such as aluminum, titanium or zirconium or an oxide thereof with the abrasive grains and doping the surface of the abrasive grains.

  Of these, colloidal silica having an organic acid immobilized thereon is particularly preferable. The organic acid is immobilized on the surface of the colloidal silica contained in the polishing composition, for example, by chemically bonding a functional group of the organic acid to the surface of the colloidal silica. If the colloidal silica and the organic acid are simply allowed to coexist, the organic acid is not fixed to the colloidal silica. For immobilizing sulfonic acid, which is a kind of organic acid, on colloidal silica, see, for example, “Sulphonic acid-functionalized silica through quantitative oxides of thiol groups”, Chem. Commun. 246-247 (2003). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica, and then the sulfonic acid is immobilized on the surface by oxidizing the thiol group with hydrogen peroxide. The colloidal silica thus obtained can be obtained. Alternatively, if the carboxylic acid is immobilized on colloidal silica, for example, “Novel Silene Coupling Agents Containing a Photolabile 2-Nitrobenzoyl Ether for the Introducing the Carboxy Group” 229 (2000). Specifically, colloidal silica having a carboxylic acid immobilized on the surface can be obtained by irradiating light after coupling a silane coupling agent containing a photoreactive 2-nitrobenzyl ester to colloidal silica. .

  The average degree of association of the abrasive grains is also less than 5.0, more preferably 3.0 or less, and even more preferably 2.5 or less. As the average degree of association of the abrasive grains becomes smaller, the surface roughness due to the shape of the abrasive grains can be improved within such a range.

  The average degree of association of the abrasive grains is also preferably 1.0 or more, and more preferably 1.05 or more. This average degree of association is obtained by dividing the value of the average secondary particle diameter of the abrasive grains by the value of the average primary particle diameter. As the average degree of association of the abrasive grains increases, there is an advantageous effect that the polishing rate of the object to be polished by the polishing composition is improved.

  The lower limit of the average primary particle diameter of the abrasive grains is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more. Further, the upper limit of the average primary particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less. Within such a range, the polishing rate of the object to be polished by the polishing composition is improved, and the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition is further suppressed. be able to. In addition, the average primary particle diameter of an abrasive grain is calculated based on the specific surface area of the abrasive grain measured by BET method, for example.

  The lower limit of the average secondary particle diameter of the abrasive grains is preferably 15 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. Further, the upper limit of the average secondary particle diameter of the abrasive grains is preferably 300 nm or less, more preferably 260 nm or less, and further preferably 220 nm or less. Within such a range, the polishing rate of the object to be polished by the polishing composition is improved, and the occurrence of surface defects on the surface of the object to be polished after polishing with the polishing composition is further suppressed. be able to. The secondary particles referred to here are particles formed by association of abrasive grains in the polishing composition, and the average secondary particle diameter of the secondary particles is measured by, for example, a dynamic light scattering method. be able to.

The upper limit of the aspect ratio of the abrasive grains in the polishing composition is less than 2.0, preferably 1.8 or less, and more preferably 1.5 or less. Within such a range, the surface roughness caused by the shape of the abrasive grains can be made favorable. The aspect ratio is a value obtained by taking the smallest rectangle circumscribing the image of the abrasive grains with a scanning electron microscope and dividing the length of the long side of the rectangle by the length of the short side of the same rectangle. And can be obtained using general image analysis software.
The lower limit of the aspect ratio of the abrasive grains in the polishing composition is 1.0 or more. The closer to this value, the better the surface roughness due to the shape of the abrasive grains.

  In the particle size distribution obtained by the laser diffraction scattering method in the abrasive grains in the polishing composition, the particle diameter D90 when the cumulative particle weight reaches 90% of the total particle weight from the fine particle side and 10 of the total particle weight of all the particles. %, The lower limit of D90 / D10, which is the ratio of the particle diameter D10 when reaching%, is 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. Further, in the particle size distribution obtained by the laser diffraction scattering method in the abrasive grains in the polishing composition, the particle diameter D90 and the total particle weight of all particles when the cumulative particle weight reaches 90% of the total particle weight from the fine particle side. The upper limit of the ratio D90 / D10 of the particle diameter D10 when reaching 10% is not particularly limited, but is preferably 2.04 or less. Within such a range, the surface roughness caused by the shape of the abrasive grains can be made favorable.

  The lower limit of the content of abrasive grains in the polishing composition is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and most preferably 1% by weight or more. . Further, the upper limit of the content of the abrasive grains in the polishing composition is preferably 50% by weight or less, more preferably 30% by weight or less, and further preferably 20% by weight or less. Within such a range, the polishing rate of the polishing object can be improved, and the cost of the polishing composition can be reduced, and the surface on the surface of the polishing object after polishing with the polishing composition can be reduced. It is possible to further suppress the occurrence of defects.

[Oxidant]
The polishing composition of the present invention essentially contains an oxidizing agent as a characteristic constituent. Specific examples of the oxidizing agent according to the present invention include hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid; persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate. . These oxidizing agents may be used alone or in combination of two or more.

  Among them, persulfate and hydrogen peroxide are preferable, and hydrogen peroxide is particularly preferable.

  The lower limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, and 0.01% by weight or more. More preferably it is. There is an advantage that the polishing rate by the polishing composition is improved as the content of the oxidizing agent is increased.

  Further, the upper limit of the content (concentration) of the oxidizing agent in the polishing composition is preferably 10% by weight or less, more preferably 5% by weight or less, and further preferably 1% by weight or less. preferable. As the content of the oxidizing agent decreases, the material cost of the polishing composition can be reduced, and the processing of the polishing composition after polishing, that is, the advantage of reducing the load of waste liquid treatment can be achieved. Have. Further, excessive oxidation of the surface of the object to be polished is less likely to occur, and there is an advantage of reducing the roughness of the metal surface after polishing.

[water]
The polishing composition of the present invention preferably contains water as a dispersion medium or solvent for dispersing or dissolving each component. From the viewpoint of suppressing the inhibition of the action of other components, water containing as little impurities as possible is preferable. Specifically, after removing impurity ions with an ion exchange resin, pure water from which foreign matters are removed through a filter is used. Water, ultrapure water, or distilled water is preferred.

[Other ingredients]
The polishing composition of the present invention is used to dissolve pH adjusters, complexing agents, metal anticorrosives, antiseptics, antifungal agents, reducing agents, water-soluble polymers, and poorly soluble organic substances as necessary. Other components such as an organic solvent may be further included. Hereinafter, preferable other components, which are a pH adjuster, a complexing agent, a metal anticorrosive, an antiseptic, and an antifungal agent, will be described.

[PH adjuster]
The pH can be adjusted by adding an appropriate amount of a pH adjusting agent. The pH adjuster used as necessary to adjust the pH of the polishing composition to a desired value may be either acid or alkali, and may be either an inorganic compound or an organic compound. Good. Specific examples of the acid include inorganic acids such as sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid and phosphoric acid; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid , N-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycol Acids, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid and lactic acid and other carboxylic acids, and methanesulfonic acid, And organic acids such as organic sulfuric acid such as ethanesulfonic acid and isethionic acid. Specific examples of the alkali include ammonia, amines such as ethylenediamine and piperazine, and quaternary ammonium salts such as tetramethylammonium and tetraethylammonium. These pH regulators can be used alone or in combination of two or more.

  The lower limit of the pH of the polishing composition of the present invention is preferably 1.0 or more, more preferably 1.05 or more. As the pH of the polishing composition increases, the handling of the polishing composition becomes easier.

  Moreover, it is preferable that the upper limit of pH of polishing composition is 7 or less, More preferably, it is 5 or less. As the pH of the polishing composition decreases, the polishing rate of the metal that is the polishing object is improved.

[Complexing agent]
The complexing agent contained in the polishing composition has an action of chemically etching the surface of the polishing object, and improves the polishing rate of the polishing object by the polishing composition.

  Examples of complexing agents that can be used include inorganic acids or salts thereof, organic acids or salts thereof, nitrile compounds, amino acids, and chelating agents. These complexing agents may be used alone or in admixture of two or more. The complexing agent may be a commercially available product or a synthetic product.

  As a complexing agent, the inorganic acid or the salt of 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 action can be expected. Examples of such salts include, for example, potassium chloride, sodium sulfate, potassium nitrate, potassium carbonate, potassium tetrafluoroborate, potassium pyrophosphate, potassium oxalate, trisodium citrate, (+)-potassium tartrate, hexafluoro A potassium phosphate etc. are mentioned.

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

  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, 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, cytosine Phosphorus, .delta.-hydroxy - lysine, creatine, histidine, 1-methyl - histidine, 3-methyl - include 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, transcyclohexane Diamine tetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol ether diamine tetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS form), N- (2-carboxylateethyl) -L-aspartic acid, β -Alanine diacetate, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N, N'-bis (2-hydroxybenzyl) ethylenediamine-N, N'-diacetic acid 1,2-dihydroxybenzene-4,6 Such as disulfonic acid and the like.

  Among these, at least one selected from the group consisting of an inorganic acid or a salt thereof, a carboxylic acid or a salt thereof, and a nitrile compound is preferable, from the viewpoint of stability of a complex structure with a metal compound contained in a polishing object. An inorganic acid or a salt thereof is more preferable. Moreover, when using what has pH adjustment function (for example, various acids etc.) as various complexing agents mentioned above, you may utilize the said complexing agent as at least one part of a pH adjusting agent.

  The lower limit of the content (concentration) of the complexing agent in the polishing composition is not particularly limited because the effect is exhibited even in a small amount, but is preferably 0.001 g / L or more, 0.01 g / L or more is more preferable, and 1 g / L or more is more preferable. In addition, the upper limit of the content (concentration) of the complexing agent in the polishing composition of the present invention is preferably 20 g / L or less, more preferably 15 g / L or less, and 10 g / L or less. More preferably it is. If it is such a range, the grinding | polishing speed | rate of a grinding | polishing target object will improve, and it is advantageous when improving the smoothness of the surface of a grinding | polishing target object after grind | polishing using a polishing composition.

[Metal anticorrosive]
By adding a metal anticorrosive to the polishing composition, it is possible to prevent deterioration of the surface condition such as surface roughness of the polished surface by preventing dissolution of the metal.

  The metal anticorrosive that can be used is not particularly limited, but is preferably a heterocyclic compound or a surfactant. The number of heterocyclic rings in the heterocyclic compound is not particularly limited. The heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. These metal anticorrosives may be used alone or in combination of two or more. In addition, as the metal anticorrosive, a commercially available product or a synthetic product may be used.

  Specific examples of heterocyclic compounds that can be used as metal anticorrosives include, for example, pyrrole compounds, pyrazole compounds, imidazole compounds, triazole compounds, tetrazole compounds, pyridine compounds, pyrazine compounds, pyridazine compounds, pyridine compounds, indolizine compounds, indoles. Compound, isoindole compound, indazole compound, purine compound, quinolidine compound, quinoline compound, isoquinoline compound, naphthyridine compound, phthalazine compound, quinoxaline compound, quinazoline compound, cinnoline compound, buteridine compound, thiazole compound, isothiazole compound, oxazole compound, iso Examples thereof include nitrogen-containing heterocyclic compounds such as oxazole compounds and furazane compounds.

  More specific examples include pyrazole compounds such as 1H-pyrazole, 4-nitro-3-pyrazolecarboxylic acid, 3,5-pyrazolecarboxylic 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-methyl Pyrazole, 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, 6-methyl-1H-pyrazolo [3,4-b] pyridine - amine.

  Examples of imidazole compounds include, for example, 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, 5-nitrobenzimidazole and the like.

  Examples of the triazole compound include, for example, 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 , 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) amino Methyl] -5-methylbenzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] -4-methylbenzotriazole, and the like.

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

  Examples of indazole compounds include, for example, 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, 3-carboxy-5-methyl-1H-indazole and the like.

  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-hydroxy-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- Ndole, 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- Ndole, 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 and the like.

  Among these, preferred heterocyclic compounds are triazole compounds, and in particular, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 5,6-dimethyl-1H-benzotriazole, 1- [N, N-bis (hydroxy Ethyl) aminomethyl] -5-methylbenzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] -4-methylbenzotriazole, 1,2,3-triazole, and 1,2,4-triazole Is preferred. Since these heterocyclic compounds have high chemical or physical adsorptive power to the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in improving the smoothness of the surface of the object to be polished after polishing with the polishing composition of the present invention.

  Examples of the surfactant used as the metal anticorrosive include an anionic surfactant, a cationic surfactant, and an amphoteric surfactant.

  Examples of anionic surfactants include, for example, polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfuric acid ester, alkyl sulfuric acid ester, polyoxyethylene alkyl ether sulfuric acid, alkyl ether sulfuric acid, alkylbenzene sulfonic acid, alkyl phosphoric acid ester , Polyoxyethylene alkyl phosphate ester, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof.

  Examples of the cationic surfactant include alkyl trimethyl ammonium salt, alkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt, alkyl amine salt and the like.

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

  Specific examples of nonionic surfactants include, for example, polyoxyalkylene alkyl ethers such as polyoxyethylene alkyl ether, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkyl amines, and alkyl alkanols. Amides are mentioned. Of these, polyoxyalkylene alkyl ether is preferred.

  Among these, preferred surfactants are polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, and alkylbenzene sulfonate. Since these surfactants have a high chemical or physical adsorption force to the surface of the object to be polished, a stronger protective film can be formed on the surface of the object to be polished. This is advantageous in improving the flatness of the surface of the object to be polished after polishing using the polishing composition of the present invention.

  The lower limit of the content of the metal anticorrosive in the polishing composition is preferably 0.001 g / L or more, more preferably 0.005 g / L or more, and 0.01 g / L or more. Is more preferable. Further, the upper limit of the content of the metal anticorrosive in the polishing composition is preferably 10 g / L or less, more preferably 5 g / L or less, and further preferably 2 g / L or less. If it is such a range, melt | dissolution of a metal can be prevented and deterioration of surface conditions, such as surface roughness of a grinding | polishing surface, can be suppressed.

[Preservatives and fungicides]
Examples of the antiseptic and fungicide used in the present invention include isothiazoline-based antiseptics such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, Paraoxybenzoates, phenoxyethanol and the like can be mentioned. These antiseptics and fungicides may be used alone or in combination of two or more.

[Method for producing polishing composition]
The manufacturing method in particular of the polishing composition of this invention is not restrict | limited, For example, it can obtain by stirring and mixing an abrasive grain, an oxidizing agent, and another component as needed.

  Although the temperature at the time of mixing each component is not specifically limited, 10-40 degreeC is preferable and you may heat in order to raise a dissolution rate. Further, the mixing time is not particularly limited.

[Polishing method and substrate manufacturing method]
As described above, the polishing composition of the present invention is suitably used for polishing a polishing object having a metal-containing layer. Therefore, this invention provides the grinding | polishing method which grind | polishes the grinding | polishing target object which has a layer containing a metal with the polishing composition of this invention. Moreover, this invention provides the manufacturing method of the board | substrate including the process of grind | polishing the grinding | polishing target object which has a layer containing a metal with the said grinding | polishing method.

  As a polishing apparatus, a general holder having a polishing surface plate on which a holder for holding a substrate having a polishing object and a motor capable of changing the number of rotations are attached and a polishing pad (polishing cloth) can be attached. A polishing apparatus can be used.

  As the polishing pad, a general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used without particular limitation. It is preferable that the polishing pad is grooved so that the polishing liquid accumulates.

  Regarding the polishing conditions, for example, the rotational speed of the polishing platen is preferably 10 to 500 rpm, and the pressure (polishing pressure) applied to the substrate having the object to be polished is preferably 0.5 to 10 psi. The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying with a pump or the like is employed. Although the supply amount is not limited, it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

  After the polishing is completed, the substrate is washed in running water, and water droplets adhering to the substrate are removed by a spin dryer or the like, and dried to obtain a substrate having a metal-containing layer.

  The polishing composition of the present invention may be a one-component type or a multi-component type including a two-component type. The polishing composition of the present invention may be prepared by diluting the stock solution of the polishing composition, for example, 10 times or more using a diluent such as water.

  The polishing composition of the present invention is preferably used in a metal polishing step, particularly a tungsten polishing step. Further, the polishing composition of the present invention comprises a tungsten polishing step, a main polishing step performed to remove most of the tungsten-containing layer, and a buff polishing step for final polishing the tungsten-containing layer and the insulator layer. It is preferably used in the buffing process when roughly classified into

  The present invention will be described in further detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

(Examples 1-7, Comparative Example 1)
Colloidal silica having the conditions shown in Table 2 below as abrasive grains and hydrogen peroxide as an oxidizing agent were mixed, and citric acid was mixed as a pH adjusting agent while adjusting with a pH meter to adjust to pH 2.1. (Mixing temperature: about 25 ° C., mixing time: about 10 minutes)

Measuring the aspect ratio of the abrasive grains;
The aspect ratio of the colloidal silica as the abrasive used to prepare the polishing composition is the length of the long side of the rectangle when the smallest rectangle circumscribing the image of the colloidal silica particles by a scanning electron microscope is taken. Was divided by the length of the short side of the same rectangle, and the average of the values obtained was measured. In addition, the measurement was calculated | required using the image analysis software about the image acquired with the scanning electron microscope.

Measurement of surface roughness of metal surfaces;
Using each polishing composition of Examples 1 to 7 and Comparative Example 1, a 200 mm wafer on which a tungsten film was formed on a silicon substrate was polished for 60 seconds, and then the substrate surface with ultrapure water on the same platen The surface roughness “Rms” of the tungsten surface on the substrate surface was measured, and the evaluation results are shown in the “Rms” column of Table 2. The polishing conditions are as shown in Table 1, and the Rms measurement conditions are as shown in Table 3.
If the value of the measured surface roughness “Rms” is 1.5 nm or less, it is a practical level.

  As shown in Table 2 above, when the polishing compositions of Examples 1 to 7 were used, the surface roughness value was compared with the polishing composition of Comparative Example 1 that did not satisfy the conditions of the present invention. It was confirmed that the surface state could be reduced by reducing the size.

Claims (9)

  A polishing composition comprising abrasive grains and an oxidizing agent, wherein the average degree of association of the abrasive grains is less than 5.0.   The polishing composition according to claim 1, wherein the abrasive grains are colloidal silica.   The polishing composition according to claim 1, wherein the value of the aspect ratio of the abrasive grains is less than 2.0.   The polishing composition according to any one of claims 1 to 3, wherein a value of D90 / D10 of the abrasive grains is 2.04 or less.   The polishing composition according to any one of claims 1 to 4, which is used for polishing a polishing object having a layer containing a metal.   The polishing composition according to claim 5, wherein the metal is tungsten or an alloy thereof.   The polishing composition according to claim 6, wherein the polishing composition is used in a buff polishing step of finishing polishing a surface of an object to be polished having a layer containing tungsten and an insulator layer.   The grinding | polishing method which grind | polishes the grinding | polishing target object which has a layer containing a metal using the polishing composition of any one of Claims 1-7.   The manufacturing method of a board | substrate including the process of grind | polishing the grinding | polishing target object which has a layer containing a metal with the grinding | polishing method of Claim 8.