WO2016208445A1 - Polishing method, composition for removing impurity, substrate, and method for manufacturing same - Google Patents

Abstract

Provided is a polishing method with which it is possible to sufficiently remove impurities present on an object to be polished. An object to be polished that has an organic film on the surface thereof is polished using a polishing composition that contains abrasive grains, and is subsequently polished using an impurity-removing composition that contains an organic compound to eliminate impurities present on the object to be polished. The organic compound contains a surfactant and/or a water-soluble polymer. The surfactant contains a hydrophilic group and a hydrophobic group that includes a C3 or higher hydrocarbon group, and the main chain of the water-soluble polymer is hydrophobic.

Description

Polishing method, impurity removing composition, substrate and method for producing the same

The present invention relates to a polishing method for polishing a polishing object having an organic film on the surface, and a composition for removing impurities used in the polishing method. Moreover, this invention relates to the board | substrate manufactured using the said grinding | polishing method, and its manufacturing method.

2. Description of the Related Art In recent years, with the formation of multilayer wiring on the surface of a semiconductor substrate, a so-called chemical mechanical polishing (CMP) technique that physically polishes and flattens the semiconductor substrate is used. ing. CMP is a technique for flattening the surface of an object to be polished, such as a semiconductor substrate, using a polishing composition (slurry) containing abrasive grains, anticorrosives, surfactants, and the like. Silicon, polysilicon, silicon An oxide film, silicon nitride, metal wiring, plugs, and an organic film formed on the surface of the semiconductor substrate are polished.

A large amount of impurities (defects) remain on the surface of the semiconductor substrate after the CMP process. As impurities, abrasive grains derived from the polishing composition used in CMP, metals, organic substances (for example, anticorrosives, surfactants), silicon-containing materials and organic films that are objects to be polished, metal wirings, plugs, etc. This includes silicon-containing materials and metals generated by polishing, and organic substances such as pad scraps generated from the polishing pad used for polishing.

If the surface of the semiconductor substrate is contaminated with these impurities, these impurities adversely affect the electrical characteristics of the semiconductor, which may reduce the reliability of the device. Furthermore, when the contamination by organic matter is significant, the device may be destroyed. Therefore, it is necessary to clean the semiconductor substrate after the CMP process to remove these impurities from the surface of the semiconductor substrate.

A cleaning agent is used for cleaning the semiconductor substrate. For example, in the technique disclosed in Patent Document 1, impurities are removed from the surface of the semiconductor substrate by immersing the semiconductor substrate in the cleaning agent.
However, the technique disclosed in Patent Document 1 cannot sufficiently remove impurities from the surface of the semiconductor substrate, and there is a problem that a large amount of impurities may remain on the surface of an object to be polished such as a semiconductor substrate. there were.

International Publication No. 2005/040324 Pamphlet Japan Patent Publication No. 268409, 2005 Japanese Patent Publication No. 2004 No. 335896

Therefore, an object of the present invention is to provide a polishing method capable of solving the above-described problems of the prior art and sufficiently removing impurities present on the polished object to be polished. It is another object of the present invention to provide an impurity removal composition that can sufficiently remove impurities present on a polishing object. Furthermore, it is another object to provide a substrate from which impurities are sufficiently removed from the surface and a method for manufacturing the same.

In order to solve the above problems, a polishing method according to one embodiment of the present invention includes a polishing step of polishing a polishing object having an organic film on a surface using a polishing composition containing abrasive grains, and a polishing step. An impurity removing step of polishing the polished object using an impurity removing composition containing an organic compound to remove impurities present on the object to be polished, the organic compound being a surfactant And the surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms, and the water-soluble polymer has a hydrophobic main chain. It is a summary.

The gist of a method for manufacturing a substrate according to another aspect of the present invention includes a step of polishing a substrate having an organic film on the surface by the polishing method according to the above aspect.
Furthermore, the gist of a substrate according to another aspect of the present invention is manufactured by the method for manufacturing a substrate according to the other aspect.
Furthermore, the impurity removing composition according to another aspect of the present invention is an impurity removing composition used for removing impurities present on a polishing object having an organic film on the surface, wherein the organic compound is an organic compound. The organic compound has at least one of a surfactant and a water-soluble polymer, and the surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms, and is water-soluble. The main point of the functional polymer is that the main chain is hydrophobic.

According to the present invention, impurities present on the object to be polished can be sufficiently removed.

An embodiment of the present invention will be described in detail below. In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. In addition, various changes or improvements can be added to the present embodiment, and forms to which such changes or improvements are added can also be included in the present invention.
The polishing method of this embodiment is a method for polishing a polishing object having an organic film on the surface, and polishing the polishing object having an organic film on the surface using a polishing composition containing abrasive grains. A polishing step, and an impurity removal step of polishing the polishing object polished in the polishing step with an impurity removing composition containing an organic compound to remove impurities present on the polishing object. ing.

The organic compound contained in the impurity removal composition has at least one of a surfactant and a water-soluble polymer. This surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms. The water-soluble polymer has a hydrophobic main chain.
When a polishing object having an organic film on the surface is polished by such a polishing method, the polishing object can be polished while sufficiently removing impurities. That is, various impurities are present on the object to be polished after being polished in the polishing step, but the impurities present on the object to be polished can be sufficiently removed in the impurity removing step, so that the impurities are sufficiently The removed polishing object can be obtained.

Hereinafter, the polishing method and the impurity removing composition of this embodiment will be described in more detail.
1. About the polishing object The polishing object to which the polishing method of this embodiment is applied is one in which an organic film is formed on the surface of a substrate. The material of the substrate is not particularly limited, and examples thereof include simple silicon, silicon compound, metal, ceramic, and resin.

Examples of the single silicon include single crystal silicon, polycrystalline silicon (polysilicon), and amorphous silicon. Examples of the silicon compound include silicon nitride, silicon dioxide (for example, a silicon dioxide interlayer insulating film formed using tetraethoxysilane (TEOS)), silicon carbide, and the like.
Examples of the metal include tungsten, copper, aluminum, hafnium, cobalt, nickel, titanium, tantalum, gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium and the like. These metals may be contained in the form of an alloy or a metal compound.

On the other hand, the type of the organic film is not particularly limited, and examples thereof include a color filter for a liquid crystal display device, a resist, an antireflection film, and a fluorine-containing silicon insulating film.
Specific examples of the polishing object having an organic film on the surface include a substrate having an organic film on the surface. Examples of the substrate having an organic film on the surface to be polished by the polishing method of the present embodiment include a substrate having a positive or negative photoresist formed on a wafer, a color filter for a liquid crystal display device, and a liquid crystal display. Organic insulation typified by substrates formed with organic films such as transparent resin for devices and black matrix for liquid crystal panels, and CFx (fluorocarbon) films formed by plasma CVD using a CHF organic source as a source gas Examples include a substrate having a film.

2. About a grinding | polishing process and a polishing composition The grinding | polishing process in the grinding | polishing method of this embodiment is a process of grind | polishing the grinding | polishing target object which has an organic film on the surface using the polishing composition containing an abrasive grain. By this step, chemical mechanical polishing of the organic film or the substrate to be polished is performed. The polishing conditions are not particularly limited, and a polishing composition containing abrasive grains is interposed between a polishing object (for example, a substrate) having an organic film on the surface and a polishing pad, for example, a polishing apparatus (one side) A polishing object having an organic film on the surface can be polished by performing polishing under general polishing conditions using a polishing apparatus, a double-side polishing apparatus, or the like.

The kind of the polishing pad is not particularly limited, and may be a foam or a non-foam such as a cloth or a non-woven fabric, and a general non-woven fabric, a polyurethane foam, a porous fluororesin, or the like can be used. Further, the polishing pad may be subjected to groove processing for forming a groove in which the polishing composition is accumulated. Polishing pad materials include polyurethane, acrylic, polyester, acrylic-ester copolymer, polytetrafluoroethylene, polypropylene, polyethylene, poly-4-methylpentene, cellulose, cellulose ester, polyamide (nylon, aramid, etc.), polyimide, polyimide Resins such as amides, polysiloxane copolymers, oxirane compounds, phenol resins, polystyrenes, polycarbonates, and epoxy resins can be used.

The composition for polishing is not particularly limited as long as it contains abrasive grains, but may contain various additives in addition to the abrasive grains. Moreover, it is good also as the slurry which disperse | distributed the abrasive grain in the liquid medium. The polishing composition will be described in detail below.
2-1. Abrasive Grains The abrasive grains contained in the polishing composition 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, and silicon nitride particles, silicon carbide particles, and boron nitride particles. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles. Among these, silica particles are preferable, and colloidal silica is particularly preferable. These abrasive grains may be used alone or in combination of two or more.

砥 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 have been modified so that the zeta potential has a relatively large positive or negative value even under acidic conditions are strongly repelled and dispersed well even under acidic conditions. This will improve the storage stability. Such surface-modified abrasive grains can be obtained, for example, by mixing a metal such as aluminum, titanium, zirconium or the like or an oxide thereof with the abrasive grains and doping the surface of the abrasive grains.

Alternatively, the surface-modified abrasive grains in the polishing composition may be silica with an organic acid immobilized on the surface. Of these, colloidal silica having an organic acid immobilized thereon can be preferably used. The organic acid is immobilized on the colloidal silica 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.

If sulfonic acid, which is a kind of organic acid, is immobilized on colloidal silica, see, for example, “Sulphonic acid-functionalized silica through quantative oxidation 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 oxidized with hydrogen peroxide to fix the sulfonic acid on the surface. The colloidal silica thus obtained can be obtained.

Alternatively, if the carboxylic acid is to be immobilized on colloidal silica, for example, “Novel Silane Coupling Agents Containing A Phototerbile 2-Nitrobenzyl Ester for GasotropyCorpoxyCarbonoxySolfoSepoxyGloSepoxyGlass. 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. .

Content of the abrasive grain in polishing composition can be 0.1 mass% or more, Preferably it is 0.5 mass% or more. As the content of abrasive grains increases, there is an advantage that the removal rate (polishing rate) of the object to be polished by the polishing composition is improved.
The content of abrasive grains in the polishing composition can also be 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less. As the content of the abrasive grains decreases, the material cost of the polishing composition can be suppressed, and the aggregation of the abrasive grains hardly occurs. Further, by polishing the object to be polished using the polishing composition, it is easy to obtain a surface to be polished with few surface defects.

The average primary particle diameter of the abrasive grains can be 5 nm or more, preferably 7 nm or more, more preferably 10 nm or more. As the average primary particle diameter of the abrasive grains increases, the polishing rate of the object to be polished by the polishing composition increases. In addition, the value of the average primary particle diameter of an abrasive grain can be calculated based on the specific surface area of the abrasive grain measured by BET method, for example.
The average primary particle diameter of the abrasive grains can also be 100 nm or less, preferably 90 nm or less, more preferably 80 nm or less. As the average primary particle diameter of the abrasive grains decreases, a surface to be polished with few surface defects is easily obtained by polishing the object to be polished using the polishing composition.

The average secondary particle diameter of the abrasive grains can be 300 nm or less, preferably 250 nm or less, more preferably 200 nm or less. The value of the average secondary particle diameter of the abrasive grains can be measured by, for example, a laser light scattering method.
The average degree of association of the abrasive grains obtained by dividing the value of the average secondary particle diameter of the abrasive grains by the value of the average primary particle diameter can be 1.2 or more, preferably 1.5 or more. As the average degree of association of the abrasive grains increases, the polishing rate of the object to be polished by the polishing composition increases.
The average degree of association of the abrasive grains can also be 5 or less, preferably 4 or less, more preferably 3 or less. As the average degree of association of the abrasive grains decreases, a surface to be polished with few surface defects is easily obtained by polishing the object to be polished using the polishing composition.

2-2 About pH The pH of the polishing composition may be less than 10 and is preferably 5 or less. When the pH is 5 or less, the operability of the polishing composition is improved, more preferably 3 or less, and particularly preferably 2.5 or less. When the pH exceeds 5, the operability tends to decrease. The lower limit of the pH of the polishing composition is not particularly limited. However, since the dispersibility of the abrasive grains in the polishing composition improves as the pH increases, it is preferably 1 or more.

2-3 Additives In order to improve the performance of the polishing composition, a pH adjuster, an oxidizing agent, a complexing agent, an anticorrosive, a surfactant, a water-soluble polymer, an antiseptic, Various additives such as an antifungal agent may be added. As an additive, a compound having three or more oxygen atoms O and a standard potential of 0.50 V or more may be added.

[About pH adjuster]
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 any of inorganic and organic compounds. Good. As the pH adjuster, for example, nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid, citric acid and the like can be used.

[Compounds having three or more oxygen atoms O and a standard potential of 0.50 V or more]
Examples of the compound having three or more oxygen atoms O and a standard potential of 0.50 V or more include cerium ammonium nitrate ((NH ₄ ) ₂ [Ce (NO ₃ ) ₆ ]), metaperiodic acid (HIO ₄ ), Orthoperiodic acid (H ₅ IO ₆ ), perchloric acid (HClO ₄ ), perbromic acid (HBrO ₄ ), potassium bromate (KBrO ₃ ), sulfuric acid (H ₂ SO ₄ ), potassium permanganate ( KMnO ₄ ), persulfuric acid (H ₂ SO ₅ ), oxone (registered trademark), vanadium pentoxide (V ₂ O ₅ ), potassium dichromate (K ₂ Cr ₂ O ₇ ), manganese oxide (III) (Mn ₂ O _3), potassium perruthenate (KRuO _4), ruthenium tetroxide _(RuO 4), nickel oxide _{(Ni 2 O} 3), palladium hydroxide (Pd _{(OH) 4),} metastannic acid _(H 2 S O _3), nitric acid _(HNO 3), ammonium peroxydisulfate _{((NH 4) 2 S 2} O 8), selenate _(H 2 _SeO 4), peroxydisulfate _{(H 2 S 2 O 8)} , aluminum nitrate (Al (NO ₃ ) ₃ ), ammonium persulfate ((NH ₄ ) ₂ SO ₅ ), ammonium perchlorate (NH ₄ ClO ₄ ), ammonium permanganate (NH ₄ MnO ₄ ), and the like. It is not something.

Oxone is a double salt composed of potassium ion, hydrogen persulfate ion, sulfate ion, and hydrogen sulfate ion, and is a compound represented by the chemical formula 2KHSO ₅ · KHSO ₄ · K ₂ SO ₄ .
Without being bound by theory, a compound having three or more oxygen atoms O and a standard potential of 0.50 V or more has a specific structure in which it has strong oxidizing properties and has three or more oxygen atoms O. By providing, the terminal structure in the organic film can be changed from an insoluble one to a water-soluble one, and the affinity between the organic film and the abrasive grains can be increased and the mechanical action can be enhanced. .

This is simply by selecting a compound having a high standard potential (strong oxidizing power) as an oxidizing agent and changing the surface of the object to be polished into a brittle oxide, and scraping the oxide by the mechanical action of the abrasive grains, Unlike the technique of improving the polishing rate by dissolving with an agent, the additive can have the above-mentioned specific structure with a standard potential of a certain level or more, and the polishing rate can be improved. Conceivable.

If the number of oxygen atoms O is less than 3 or the standard potential is less than 0.50 V, the terminal structure in the organic film changes from insoluble to water-soluble without having strong oxidizing properties. It tends to be difficult to do. Therefore, the affinity between the organic film and the abrasive grains is weak, and it tends to be difficult to increase the mechanical action.
The content of the compound having three or more oxygen atoms O and a standard potential of 0.50 V or more can be 0.005% by mass or more, and preferably 0.01% by mass or more. As the content of the compound having three or more oxygen atoms O and a standard potential of 0.50 V or more increases, the terminal structure in the organic film can be changed to water-soluble, so that the mechanical action is improved. There is.

The content of the compound having three or more oxygen atoms O and a standard potential of 0.50 V or more can be 5.0% by mass or less, preferably 3.0% by mass or less, more preferably 1.0% by mass or less. If it is this range, the material cost of polishing composition can be held down.
The standard potential means an electrode potential when the activity of all chemical species involved in the reaction is 1 (standard state) and is in an equilibrium state for a certain electrochemical reaction. The standard potential can be measured by cyclic voltammetry or the like as a potential difference from the reference electrode.
A compound having three or more oxygen atoms O and a standard potential of 0.50 V or more can act as a pH adjuster having a pH adjusting function.

[About oxidizing agents]
The oxidizing agent has an action of oxidizing the surface of the object to be polished, and when an oxidizing agent is added to the polishing composition, there is an effect of improving the polishing rate by the polishing composition. Content of the oxidizing agent in polishing composition can be 0.1 mass% or more of polishing composition, Preferably it is 0.5 mass% or more. Moreover, content of an oxidizing agent can be 4 mass% or less of polishing composition, Preferably it is 3 mass% or less. When the content of the oxidizing agent is less than 0.1% by mass or more than 4% by mass, it tends to be difficult to obtain a practical level of organic film polishing rate.

Usable oxidizing agent is, for example, peroxide. Specific examples of the peroxide include persulfates such as hydrogen peroxide, peracetic acid, percarbonate, urea peroxide, perchloric acid, sodium persulfate, potassium persulfate, and ammonium persulfate. Among these, persulfate and hydrogen peroxide are preferable from the viewpoint of polishing rate, and hydrogen peroxide is particularly preferable from the viewpoint of stability in an aqueous solution and environmental load.

[About complexing agents]
The complexing agent optionally contained in the polishing composition has a function of chemically etching the surface of the substrate having the organic film, and functions to improve the polishing rate by the polishing composition.
The upper limit of the content of the complexing agent optionally contained in the polishing composition can be 10% by mass, preferably 1% by mass. As the content of the complexing agent decreases, excessive etching on the surface of the substrate on which the organic film is formed is less likely to occur. As a result, excessive polishing can be suppressed.

The lower limit of the content of the complexing agent optionally contained in the polishing composition can be 0.01% by mass, preferably 0.1% by mass. As the content of the complexing agent increases, the etching effect on the surface of the substrate on which the organic film is formed increases. As a result, improvement of the polishing rate by the polishing composition is promoted.
Complexing agents that can be used are, for example, inorganic acids, organic acids, and amino acids. Specific examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid. Specific examples of organic acids include 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, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, malein Examples include acid, phthalic acid, malic acid, tartaric acid, citric acid and lactic acid. Organic sulfuric acid such as methanesulfonic acid, ethanesulfonic acid, and isethionic acid can also be used. A salt such as an alkali metal salt of an inorganic acid or an organic acid may be used instead of the inorganic acid or the organic acid or in combination with the inorganic acid or the organic acid.

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, cystein Berlin, .delta.-hydroxy - lysine, creatine, histidine, 1-methyl - histidine, 3-methyl - histidine and tryptophan and the like. Among these, as the complexing agent, glycine, alanine, malic acid, tartaric acid, citric acid, glycolic acid, isethionic acid, or a salt thereof is preferable from the viewpoint of improving polishing properties.

[Anti-corrosive]
The content of the anticorrosive agent optionally contained in the polishing composition can be 0.1% by mass or more, preferably 0.2% by mass or more of the polishing composition. Moreover, content of anticorrosive agent can be 0.4 mass% or less of polishing composition, Preferably it is 0.3 mass% or less. When the content of the anticorrosive agent is less than 0.2% by mass or exceeds 0.4% by mass, it tends to be difficult to obtain a practical level of anticorrosive effect.

Examples of usable anticorrosives include heterocyclic compounds or heteroaryl compounds having at least a 5 to 6 membered ring, two or more double bonds, and one or more nitrogen atoms. . Examples thereof include compounds having a pyridine ring, a pyrazole ring, a pyrimidine ring, an imidazole ring, a triazole ring, and a benotriazole ring. Moreover, benzotriazole (BTA) can be used as an anticorrosive. When an anticorrosive agent is added, there is an effect of improving the polishing rate by the polishing composition.

[Surfactant]
The content of the surfactant optionally contained in the polishing composition can be 0.01% by mass or more, preferably 0.02% by mass or more of the polishing composition. Moreover, content of surfactant can be 2 mass% or less of polishing composition, Preferably it is 1 mass% or less. The surfactant can include one or more selected from an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant.

Examples of anionic surfactants include polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, alkyl benzene sulfonic acid, alkyl phosphate ester, Examples thereof include oxyethylene 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 alkyltrimethylammonium salt, alkyldimethylammonium salt, alkylbenzyldimethylammonium salt, alkylamine salt and the like.
Examples of amphoteric surfactants include alkylbetaines and alkylamine oxides.
Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, and alkyl alkanolamide. It is done.

Among these, preferable surfactants are polyoxyethylene alkyl ether acetate, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, alkylbenzene sulfonate, and polyoxyethylene alkyl ether.
Since these surfactants have high chemical or physical adsorption force to the surface of the object to be polished, it is possible to form a stronger film 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 with the polishing composition.

[About water-soluble polymers]
The polishing composition can contain a water-soluble polymer. The water-soluble polymer may be referred to as a surfactant. The content of the water-soluble polymer can be 0.01% by mass or more of the polishing composition, and preferably 0.02% by mass or more. Moreover, content of a water-soluble polymer can be 2 mass% or less of polishing composition, Preferably it is 1 mass% or less. Examples of water-soluble polymers that can be used include sodium polyacrylate, polyacrylamide, polyvinyl alcohol, polyethyleneimine, polyethylene oxide, and polyvinylpyrrolidone.

[About preservatives and fungicides]
The polishing composition can contain a preservative and a fungicide. Examples of antiseptics and fungicides include isothiazoline-based antiseptics such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, and paraoxybenzoic acid esters. And phenoxyethanol. These preservatives and fungicides may be used alone or in combination of two or more.

2-4 Liquid medium The polishing composition may contain a liquid medium such as water or an organic solvent. The liquid medium functions as a dispersion medium or solvent for dispersing or dissolving each component (abrasive grains, additives, etc.) of the polishing composition. Examples of the liquid medium include water and organic solvents. One kind can be used alone, or two or more kinds can be mixed and used, but it is preferable to contain water. However, it is preferable to use water containing as little impurities as possible from the viewpoint of suppressing the inhibition of the action of each component. Specifically, pure water, ultrapure water, or distilled water from which foreign substances are removed through a filter after removing impurity ions with an ion exchange resin is preferable.
The polishing composition may be a one-component type or a multi-component type such as a two-component type. Further, the polishing composition may be prepared by diluting a stock solution of the polishing composition with a liquid medium such as water.

3. About the impurity removal step and the impurity removal composition The impurity removal step in the polishing method of the present embodiment is performed by polishing the polishing object polished in the polishing step using an impurity removal composition containing an organic compound, This is a step of removing impurities present on the object to be polished. The impurity-removing composition used in the impurity removing step does not contain abrasive grains, or even if it contains a small amount, chemical mechanical polishing is not substantially performed in the impurity removing step. A process for removing impurities is performed.

A large amount of impurities (defects) may be present on the object to be polished after the polishing process. As impurities, abrasive grains derived from the polishing composition used in the polishing step, metal, additives, and base material of the object to be polished (if the object to be polished is a substrate having an organic film on its surface, metal Examples include silicon-containing materials and metals generated by polishing wiring, plugs, and the like) and organic films, and pad scraps generated from polishing pads used for polishing. By polishing a polishing object having such impurities on the surface using the impurity removing composition, a polishing object from which impurities are sufficiently removed can be obtained.

The impurity removal composition of the present embodiment can be used for a polishing object polished using a polishing composition containing abrasive grains, but is not limited to a polishing object immediately after polishing. Further, it can be used for a polishing object before polishing, or can be used for a polishing object washed after polishing. That is, regardless of the situation of the object to be polished, the impurities existing on the surface can be sufficiently removed by performing the treatment for removing the impurities using the impurity removing composition of the present embodiment. Can do.

The impurity removal step is intended to remove impurities from the object to be polished and does not require polishing. Therefore, the polishing rate of the organic film in the impurity removal step may be 0.5 nm / min or less, preferably 0.3 nm / min or less, more preferably 0.1 nm / min or less, still more preferably 0.05 nm / min or less. That is, the polishing rate of the organic film in the impurity removal step is substantially zero.

The treatment conditions for removing impurities are not particularly limited, and an impurity removing composition is interposed between a polishing object (for example, a substrate) having an organic film on the surface and a polishing pad, for example, a polishing apparatus (one side) By performing polishing under general polishing conditions using a polishing apparatus, a double-side polishing apparatus, or the like, impurities existing on an object to be polished having an organic film on the surface can be removed.

The type of polishing pad used in the impurity removal step is not particularly limited, and the polishing pad described above in item 2 can be used. However, it is preferable to use a soft polishing pad (soft pad). Specifically, the pad hardness is preferably 60 or less, and more preferably 50 or less. By using such a soft pad, scratches (scratches) generated in the organic film in the impurity removal step can be reduced. In the present specification, the pad hardness means the Shore D hardness of the polishing pad.

The impurities on the object to be polished are sufficiently removed by the impurity removing step, but a step of removing impurities remaining on the object to be polished may be further provided after the impurity removing step. For example, at least one of a water polishing step of polishing using water instead of a polishing composition or an impurity removal composition and a cleaning step of cleaning an object to be polished may be provided. The processing content of the cleaning process is not particularly limited. For example, it may be a process of applying pressure with a brush such as a sponge made of polyvinyl alcohol while pouring water or a cleaning liquid onto the object to be polished. The object to be polished after washing may be dried by removing droplets adhering to the surface with a spin dryer or the like.

The composition for removing impurities of the present embodiment is not particularly limited as long as it contains a specific organic compound to be described later, but various additives in addition to the specific organic compound can be used if desired. May be contained or abrasive grains may be contained. Alternatively, a solution in which an organic compound is dissolved in a solvent may be used. The impurity removal composition of this embodiment will be described in detail below.

3-1 Organic Compound The organic compound contained in the impurity removal composition of the present embodiment has at least one of a surfactant and a water-soluble polymer. This surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms. Further, this water-soluble polymer has a hydrophobic main chain of the polymer. These organic compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

In the impurity removal step, impurities on the object to be polished are removed by the action of the organic compound. As a mechanism by which the impurities on the object to be polished are removed by the organic compound, an impurity adhesion preventing action and an impurity detaching action are considered.
The effect of preventing the adhesion of impurities occurs when the organic compound hydrophilizes the surface of the organic film. In addition, the impurity detachment action occurs when an organic compound is emulsified and hydrated with impurities (especially organic matter) adhering to the surface of the organic film.

As for the effect of preventing the adhesion of impurities, since the organic compound itself may remain as a residue after polishing if the adsorption force of the organic compound on the organic film is strong, the adsorption force of the organic compound on the organic film may be too strong. Not suitable. Specifically, although a sulfonic acid type surfactant described later has a hydrophilizing action, it may remain as a residue itself, so the amount of impurities (number of defects) on the surface of the organic film. ) Is less effective than sulfuric acid type, phosphoric acid type and carboxylic acid type surfactants. On the other hand, even if the adsorptive power of the organic compound to the organic film is too weak, a hydrophilic film cannot be formed on the surface of the organic film, which may cause a problem that the anti-reattachment function cannot be provided. It is preferable to use an organic compound that has a suitable adsorbing power that is easily adsorbed on the organic film (the adsorbing speed is fast) and is easily desorbed.

Since the surfactant has a hydrophilic group and a hydrophobic group, the surface of the organic film can be hydrophilized, and impurities can be emulsified and hydrated. Further, since the main chain of the water-soluble polymer is hydrophobic, the surface of the organic film can be made hydrophilic, and impurities can be emulsified and hydrated.
The type of the hydrophilic group of the surfactant is not particularly limited. For example, carboxy group (—COOH), sulfo group (—SO ₃ H), ether group (—O—), hydroxy group (—OH) , At least one selected from a formyl group (—CHO) and an amino group (—NH ₂ ).

These hydrophilic groups are bonded to a hydrophobic group, but this hydrophobic group has a hydrocarbon group having 3 or more carbon atoms, and this hydrocarbon group may be an aromatic hydrocarbon group or an aliphatic hydrocarbon group. . If the number of carbon atoms of the hydrocarbon group is 3 or more, the surfactant is easily adsorbed on the surface of the organic film by hydrophobic interaction.
As the surfactant, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be used.

Specific examples of the nonionic surfactant include polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, and alkyl alkanolamides.
Specific examples of the anionic surfactant include coconut oil fatty acid sarcosine, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl ether sulfate, polyoxyethylene alkyl ether acetic acid, alkylbenzene sulfone. Examples thereof include acids, alkyl phosphate esters, polyoxyethylene alkyl phosphate esters, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, and salts thereof.

On the other hand, since the main chain of the water-soluble polymer is hydrophobic, the main chain does not have an atom having a local charge such as an oxygen atom, a nitrogen atom, or a sulfur atom, and preferably includes only a carbon atom and a hydrogen atom. Become. Therefore, specific examples of the water-soluble polymer include polyvinyl alcohol, polyglycerin, and polyoxyethylene polyglyceryl ether, and polyethylene glycol and polypropylene glycol do not correspond to organic compounds contained in the impurity removal composition.

The content of the organic compound in the impurity removal composition of the present embodiment is not particularly limited, but may be 0.001% by mass or more and 10% by mass or less. If it is 0.001% by mass or more, the hydrophilic part of the organic compound will sufficiently hydrophilize the surface of the organic film, preventing the impurities from reattaching to the surface of the organic film, and the organic matter on the surface of the organic film. The effect of emulsifying and discharging out of the system is further exhibited. On the other hand, if it is 10 mass% or less, the possibility that the organic compound itself remains as a residue on the surface of the organic film is reduced, and the storage stability of the impurity removing composition is hardly deteriorated.

3-2 Additives In order to improve the performance of the impurity removal composition of the present embodiment, a pH adjuster, an oxidizing agent, a complexing agent, an anticorrosive, an antiseptic, and an antifungal agent are added as necessary. You may add various additives, such as. Since these additives that can be blended in the impurity removal composition of the present embodiment are the same as the additives described in Section 2-3, description thereof will be omitted.

3-3 Solvent As described above, the impurity removal composition of the present embodiment may be a solution in which an organic compound is dissolved in a solvent. The kind of solvent is not particularly limited, and examples thereof include water and organic solvents. These solvents can be used alone or as a mixture of two or more, but preferably contain water. However, it is preferable to use water containing as little impurities as possible from the viewpoint of suppressing the inhibition of the action of the organic compound or additive. Specifically, pure water, ultrapure water, or distilled water from which foreign substances are removed through a filter after removing impurity ions with an ion exchange resin is preferable.

3-4 Abrasive Grains The impurity removing composition may or may not contain abrasive grains. When it contains abrasive grains, a small amount is preferred. When the composition for removing impurities does not contain abrasive grains, the composition for removing impurities may be in the form of a solution instead of a slurry without blending other solid materials. Moreover, when the composition for impurity removal contains an abrasive grain, the content is preferably 0% by mass to 0.01% by mass or less. The type of abrasive grains is not particularly limited, and the abrasive grains described above in Section 2-1 can be used, but colloidal silica is preferred. The particle size of the abrasive grains is not particularly limited, and the abrasive grains having the average primary particle diameter and the average secondary particle diameter described in Section 2-1 can be used.

〔Example〕
Hereinafter, the present invention will be described more specifically with reference to Table 1 by showing Examples and Comparative Examples.
(Example 1)
A polishing object having an organic film on the surface is polished with a polishing machine (chemical mechanical polishing) using a polishing composition containing abrasive grains, and then an impurity removing composition containing an organic compound is used. Polishing was performed with a polishing machine (treatment for removing impurities) to remove impurities present on the object to be polished. Then, the polishing object was water-polished with a polishing machine and further washed, and then the amount of impurities present on the polishing object was measured.

The object to be polished is a silicon wafer, and a resist film using an ArF excimer laser (wavelength 193 nm) as an exposure light source is formed as an organic film on the surface.
The polishing composition is a slurry composed of colloidal silica (abrasive grains), polyvinylpyrrolidone (additive), and water (liquid medium). The content of colloidal silica in the polishing composition is 2% by mass, and polyvinylpyrrolidone. The content of is 0.1% by mass. Moreover, the average primary particle diameter of colloidal silica is 30 nm, and an average secondary particle diameter is 60 nm.

The impurity removal composition is a pH 7.0 aqueous solution composed of a surfactant (organic compound) and water, and the content of the surfactant in the impurity removal composition is 0.1% by mass. As the surfactant, coconut oil fatty acid sarcosine triethanolamine was used as shown in Table 1. Coconut oil fatty acid sarcosine triethanolamine is an anionic surfactant having a carboxy group as a hydrophilic group and a hydrocarbon group constituting coconut oil fatty acid as a hydrophobic group.

As a polishing apparatus, a CMP apparatus F-REX300E (product name) manufactured by Ebara Manufacturing Co., Ltd. was used for any of chemical mechanical polishing, treatment for removing impurities, and water polishing. As the polishing pad, a foamed polyurethane resin laminated polishing pad (trade name IC-1010) manufactured by Rohm and Haas is used for any of chemical mechanical polishing, treatment for removing impurities, and water polishing. It was.

The polishing conditions for chemical mechanical polishing are a polishing pressure of 3.4 kPa (0.5 psi), a platen and carrier rotation speed of 10 rpm, a polishing time of 5 seconds, and a polishing composition supply rate of 300 ml / min. In the treatment for removing impurities, the polishing pressure is 3.4 kPa (0.5 psi), the rotation speed of the surface plate and the carrier is 30 rpm, the polishing time is 60 seconds, and the supply speed of the impurity removing composition is 300 ml / min.
The amount of impurities present on the object to be polished was measured using a wafer surface inspection device Surfscan SP1 manufactured by KLA-Tencor. Impurities detected by this apparatus have a diameter of 0.5 μm or more. The results are shown in Table 1.

(Examples 2 to 11 and 13)
In the same manner as in Example 1 except that the type of the organic compound used in the impurity removal composition was changed to the surfactant shown in Table 1, the chemical compound for the polishing object having an organic film on the surface was used. After performing mechanical mechanical polishing, treatment for removing impurities, water polishing, and cleaning, the amount of impurities present on the object to be polished was measured. The results are shown in Table 1.
In addition, “POE” such as “POE dodecyl ether ammonium sulfate” described in Table 1 means “polyoxyethylene”, and “POA” of “POA allyl phenyl ether ammonium sulfate” means “polyoxyalkylene”. .

Example 12
In the same manner as in Example 1 except that the type of the organic compound used in the impurity removal composition was changed to the water-soluble polymer shown in Table 1, the chemical compound for the polishing object having an organic film on the surface was used. After performing mechanical mechanical polishing, treatment for removing impurities, water polishing, and cleaning, the amount of impurities present on the object to be polished was measured. The results are shown in Table 1. Polyvinyl alcohol which is a water-soluble polymer has a hydroxyl group as a hydrophilic group and a hydrocarbon group constituting the main chain of polyvinyl alcohol as a hydrophobic group.

(Examples 14 to 19)
Except for the point that the types of organic compounds used in the impurity removal composition were changed to the surfactants shown in Table 1, respectively, and the pH was adjusted to 2.7 by adding nitric acid to the impurity removal composition. In the same manner as in Example 1, the object to be polished having an organic film on the surface is subjected to chemical mechanical polishing, treatment for removing impurities, water polishing, and cleaning, and then present on the object to be polished. The amount of impurities was measured. The results are shown in Table 1.

(Examples 20 to 22)
Implemented except that the type of organic compound used in the impurity removal composition was changed to the surfactant shown in Table 1 and that the pH was adjusted to 10 by adding ammonia to the impurity removal composition. In the same manner as in Example 1, after performing chemical mechanical polishing, treatment for removing impurities, water polishing, and cleaning on a polishing object having an organic film on the surface, impurities existing on the polishing object are removed. The amount was measured. The results are shown in Table 1.

(Comparative Example 1)
In the treatment for removing impurities, except for using water instead of the composition for removing impurities, in the same manner as in Example 1, chemical mechanical polishing, impurities on a polishing object having an organic film on the surface The amount of impurities present on the object to be polished was measured after carrying out the treatment for removing water, water polishing, and cleaning. The results are shown in Table 1.

(Comparative Examples 2 and 3)
Except that the type of organic compound used in the impurity removal composition was changed to the polymer compound shown in Table 1, the same manner as in Example 1 was applied to the polishing object having an organic film on the surface. After performing mechanical mechanical polishing, treatment for removing impurities, water polishing, and cleaning, the amount of impurities present on the object to be polished was measured. The results are shown in Table 1.

From the results shown in Table 1, in Examples 1 to 22, the amount of impurities present on the object to be polished was smaller than that in Comparative Examples 1 to 3, and polishing was performed using an impurity removing composition containing an organic compound. It can be seen that the impurities are sufficiently removed by polishing with a machine. In Comparative Examples 2 and 3, since the main chain of the polymer compound, which is an organic compound blended in the impurity removal composition, is hydrophilic rather than hydrophobic, the impurities are sufficiently removed by the treatment for removing the impurities. There wasn't.

Claims (12)

1. A polishing step of polishing an object to be polished having an organic film on the surface using a polishing composition containing abrasive grains;
   Polishing the polishing object polished in the polishing step using an impurity-removing composition containing an organic compound to remove impurities present on the polishing object; and
   With
   The organic compound has at least one of a surfactant and a water-soluble polymer,
   The polishing method wherein the surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms, and the water-soluble polymer has a hydrophobic main chain.
2. The polishing method according to claim 1, wherein the impurity removing composition does not contain abrasive grains.
3. The polishing method according to claim 1 or 2, wherein a polishing rate of the organic film in the impurity removing step is 0.5 nm / min or less.
4. The polishing method according to any one of claims 1 to 3, wherein the content of the organic compound in the impurity removing composition is 0.001 mass% or more and 10 mass% or less.
5. The polishing method according to any one of claims 1 to 4, wherein the hydrophilic group is at least one selected from a carboxy group, a sulfo group, an ether group, and a hydroxy group.
6. A method for producing a substrate comprising a step of polishing a substrate having an organic film on the surface by the polishing method according to any one of claims 1 to 5.
7. A substrate manufactured by the method for manufacturing a substrate according to claim 6.
8. An impurity removing composition used for removing impurities present on an object to be polished having an organic film on its surface,
   Contains organic compounds,
   The organic compound has at least one of a surfactant and a water-soluble polymer,
   The surfactant has a hydrophilic group and a hydrophobic group having a hydrocarbon group having 3 or more carbon atoms, and the water-soluble polymer has a hydrophobic main chain.
9. The composition for removing impurities according to claim 8, which contains no abrasive grains.
10. The impurity removing composition according to claim 8 or 9, which is used for the polishing object polished using a polishing composition containing abrasive grains.
11. The impurity removal composition according to any one of claims 8 to 10, wherein the content of the organic compound is 0.001% by mass or more and 10% by mass or less.
12. 12. The impurity removing composition according to claim 8, wherein the hydrophilic group is at least one selected from a carboxy group, a sulfo group, an ether group, and a hydroxy group.