TW201412962A - Polishing composition, method for producing the polishing composition, and method for producing semiconductor substrate using the polishing composition - Google Patents

Abstract

A polishing composition comprises a water-soluble polymer that is a solid raw material, a dissolution inhibitor that serves to reduce the solubility of the water-soluble polymer in water, and water. In the polishing composition, a C/(AB) value is 70 10-3 or less, wherein A represents the weight average molecular weight of the water-soluble polymer, B represents the content [% by mass] of the water-soluble polymer in the polishing composition, and C represents the content [ppm by mass] of the dissolution inhibitor in the polishing composition.

Description

Polishing composition, method for producing the polishing composition, and method for producing a semiconductor substrate using the polishing composition

The present invention relates to a polishing composition, a method for producing the polishing composition, and a method for producing a semiconductor substrate using the polishing composition. The semiconductor substrate in the present specification includes a polished single crystal germanium substrate (hereinafter also referred to simply as "germanium substrate"), or a substrate obtained by forming an integrated circuit on the germanium substrate.

A method of polishing a tantalum substrate is generally known in which a polishing composition is supplied to a surface of a tantalum substrate for polishing. When the polishing method using such a polishing composition is used, the particles on the surface of the substrate after polishing may remain on the surface of the substrate, and the particles may adhere thereto. In the increase in the demand for low defects and high smoothness of the tantalum substrate, it is extremely important to suppress the adhesion of particles due to the polishing composition. For example, the polishing composition disclosed in Patent Document 1 contains a specific molecular weight and a specific HLB. A component such as a nonionic active agent, whereby the adhesion of the particles to the surface of the substrate after polishing is suppressed.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] JP-A-2011-181765

As a result of active research, the present inventors have found that the polishing composition contains a water-soluble polymer of a solid raw material, a dissolution inhibitor which reduces the water dissolution rate of the water-soluble polymer, and the weight of the water-soluble polymer by water. The average molecular weight, the content of the water-soluble polymer, and the content of the dissolution inhibitor satisfy a specific relationship, and the adhesion of the particles to the surface of the substrate after polishing can be suppressed. The present invention has been made in view of the above findings, and an object thereof is to provide a polishing composition capable of suppressing adhesion of particles to a surface after polishing of an object to be polished, a method for producing the polishing composition, and a composition for polishing the same. A method of manufacturing a semiconductor substrate.

In order to achieve the above object, the present invention provides a polishing composition which is a water-soluble polymer containing a solid raw material, a dissolution inhibitor which functions to reduce the water solubility of the water-soluble polymer, and water, and The weight average molecular weight of the water-soluble polymer is A, the content of the water-soluble polymer in the polishing composition [% by mass] is B, and the content of the dissolution inhibitor in the polishing composition [ppm by mass] When C is set, the value of C/(A × B) is 70 × 10 ^-3 or less.

The content of the dissolution inhibitor in the polishing composition is preferably 80 ppm by mass or less.

The weight average molecular weight of the water-soluble polymer is preferably 1,000,000 or less.

The polishing composition is preferably used for polishing a ruthenium substrate.

The polishing composition is preferably used for the final polishing of the ruthenium substrate.

Further, another aspect of the present invention provides a method for producing a polishing composition comprising a surface-treated water-soluble polymer having an addition of the dissolution inhibitor on a surface of the water-soluble polymer, mixed in water, and dissolved The steps.

Still another aspect of the present invention provides a method of producing a semiconductor substrate comprising the step of polishing a germanium substrate using the polishing composition of the above-described state.

According to the polishing composition of the present invention, the adhesion of the particles to the polished surface of the object to be polished can be suppressed. Further, according to the method for producing a polishing composition of the present invention, it is possible to produce a polishing composition which can suppress adhesion of particles to the surface after polishing of the object to be polished. Further, according to the method for producing a semiconductor substrate of the present invention, a high-quality semiconductor substrate can be obtained.

Hereinafter, an embodiment of the present invention will be described.

The polishing composition of the present embodiment contains a water-soluble polymer of a solid raw material, a dissolution inhibitor which exhibits water solubility which reduces water-soluble high score, and water. The polishing composition preferably further contains abrasive grains, a basic compound, a chelating agent, and a surfactant. The polishing composition is prepared by mixing various components such as a water-soluble polymer in water.

The polishing composition is used for polishing the surface of the crucible substrate. The polishing of the ruthenium substrate includes, for example, a pre-polishing step (primary polishing and secondary polishing) for flattening the surface of the disk-shaped ruthenium substrate sliced from the ruthenium single crystal ingot, and removing the pre-polished ruthenium substrate surface The final grinding step of fine concavo-convex and mirroring. The polishing composition is preferably used in the final grinding step. The tantalum substrate on which the surface is polished using the polishing composition can be preferably used for the production of a semiconductor substrate.

(water)

The water system is a dispersion medium or a solvent of other components in the polishing composition. The water preferably does not hinder the action of other components contained in the polishing composition. Examples of such water are, for example, water having a total content of transition metal ions of 100 ppb or less. The purity of water can be improved by, for example, removal of impurity ions using an ion exchange resin, removal of particles by a filter, and operation by distillation or the like. Specifically, ion-exchanged water, pure water, ultrapure water, distilled water or the like is preferably used.

(water soluble polymer)

The water-soluble polymer functions to improve the wettability of the surface of the ruthenium substrate when it is subjected to surface treatment of the substrate such as polishing or washing. When the water-soluble polymer is prepared in the polishing composition, it is mixed in water in a solid state. The water-soluble polymer of the solid raw material means a water-soluble polymer which is regarded as a solid state in an environment of a temperature of 23 ° C, a relative humidity of 50%, and a pressure of 1 atm before being dissolved in water. In addition, the "water-soluble polymer of a solid raw material" is only described as "water-soluble polymer".

The water-soluble polymer may be one having at least one functional group selected from the group consisting of a cationic group, an anionic group and a nonionic group in the molecule, and specifically, a hydroxyl group, a carboxyl group, a decyloxy group, a sulfo group or a quaternary nitrogen structure in the molecule may be used. Any one of a heterocyclic structure, a vinyl structure, and a polyoxyalkylene structure. Specific examples thereof include an imine derivative such as a cellulose derivative or a poly(N-fluorenylalkyleneimine), a polyvinyl alcohol derivative in which one of the hydroxyl groups of the polyvinyl alcohol is partially substituted with a 4-stage nitrogen structure, and polyethylene. Alcohol, polyvinylpyrrolidone, a polymer containing polyvinylpyrrolidone in one part of the structure, polyethylene caprolactam, a copolymer containing polyethylene caprolactam in one part of the structure, polyoxyethylene, having a polyoxyalkylene structure A polymer, a polymer having such a diblock type or a triblock type, a random type, an interactive type, and the like.

In the above water-soluble polymer, a cellulose derivative, polyvinylpyrrolidone, or a polymerization having a polyoxyalkylene group structure is used from the viewpoint of improving the wettability of the surface of the tantalum substrate, suppressing adhesion of particles, and lowering surface roughness. The material is preferred. Specific examples of the cellulose derivative are hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, ethylhydroxyl Ethyl cellulose, Carboxymethyl cellulose and the like. Among the cellulose derivatives, hydroxyethyl cellulose is preferred in terms of improving the ability to impart moisture repellency to the surface of the ruthenium substrate and having good washability. Further, the water-soluble polymer may be used singly or in combination of two or more.

The weight average molecular weight of the water-soluble polymer is preferably 1,000 or more, more preferably 10,000 or more, still more preferably 100,000 or more, and most preferably 200,000 or more in terms of polyethylene oxide. As the weight average molecular weight of the water-soluble polymer increases, the wettability of the surface of the ruthenium substrate increases. The weight average molecular weight of the water-soluble polymer is preferably 2,000,000 or less, more preferably 1,000,000 or less, still more preferably 800,000 or less, still more preferably 500,000 or less, and most preferably 300,000 or less. As the weight average molecular weight of the water-soluble polymer decreases, the stability of the polishing composition is improved. Further, when the weight average molecular weight of the water-soluble polymer is 1,000,000 or less, the degree of haze of the polished surface of the substrate after polishing can be reduced.

The content of the water-soluble polymer in the polishing composition is preferably 0.002% by mass or more, more preferably 0.004% by mass or more, still more preferably 0.006% by mass or more, still more preferably 0.008% by mass or more, and most preferably 0.01% by weight. More than % by mass. As the content of the water-soluble polymer in the polishing composition increases, the wettability of the surface of the ruthenium substrate is further improved. The content of the water-soluble polymer in the polishing composition is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, still more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and most preferably 0.03% by mass. Below mass%. As the content of the water-soluble polymer in the polishing composition is reduced, the stability of the polishing composition is improved.

(dissolution inhibitor)

The dissolution inhibitor is added to the surface of the water-soluble polymer, specifically by binding to a functional group of the water-soluble polymer, for example, a water-soluble portion (hydrophilic portion) such as a hydroxyl group, thereby temporarily reducing water solubility. The hydrophilicity of the polymer, and the water dissolution rate of the water-soluble polymer is reduced. The dissolution inhibitor is mixed in water in a state of being added to the surface of the water-soluble polymer in the preparation of the polishing composition. Hereinafter, a water-soluble polymer having a dissolution inhibitor added to the surface is referred to as a surface-treated water-soluble polymer. The surface-treated water-soluble polymer is separated into a water-soluble polymer and a dissolution inhibitor in the process of being dissolved in water. As a result, the polishing composition contains a water-soluble polymer and a dissolution inhibitor.

When the surface-treated water-soluble polymer is mixed in water, it is uniformly dispersed in water before being dissolved in water to form an aqueous dispersion. Subsequently, the water-soluble polymer and the dissolution inhibitor are produced by hydrolysis of the surface-treated water-soluble polymer to be dissolved in water. Therefore, when the water-soluble polymer is surface-treated, the solubility of the water-soluble polymer can be more significantly inhibited than in the case of using the water-soluble polymer which is not added to the surface of the dissolution inhibitor, for example, the granularity is remarkably suppressed. The block is equal to the block. As a result, adhesion of the particles to the surface of the ruthenium substrate after polishing can be suppressed.

Examples of the dissolution inhibitor are exemplified by, for example, aldehydes, and specific examples thereof include monoaldehydes such as formaldehyde, butyraldehyde, and glyceraldehyde, or oxalic acid dialdehyde (glyoxal), malonic acid dialdehyde (malondialdehyde), and succinic acid II. Dialdehyde such as aldehyde (succinaldehyde). Among them, oxalic acid dialdehyde is most preferable from the viewpoint of more preferably suppressing the adhesion of particles. The dissolution inhibitor may be used singly or in combination of two or more. use. Further, the surface treatment for adding the dissolution inhibitor to the surface of the water-soluble polymer can be carried out by a method disclosed in, for example, JP-A-49-71077 or JP-A-2000-63565.

The content of the dissolution inhibitor in the polishing composition (the content of the addition amount of the dissolution inhibitor added to the surface of the water-soluble polymer at the time of preparation of the polishing composition) is preferably 1 ppm by mass or more, more preferably 5 Above mass ppm. As the content of the dissolution inhibitor in the polishing composition increases, that is, the degree of decrease in the hydrophilicity of the water-soluble polymer when the polishing composition is prepared increases, the adhesion of the particles due to the water-soluble polymer decreases. The content of the dissolution inhibitor in the polishing composition is preferably 80 ppm by mass or less, more preferably 50 ppm by mass or less, still more preferably 30 ppm by mass or less, and most preferably 15 ppm by mass or less. As the content of the dissolution inhibitor in the polishing composition is decreased, the particle adhesion due to the dissolution inhibitor is reduced.

The content of the dissolution inhibitor in the polishing composition is set to satisfy a specific relationship with respect to the weight average molecular weight of the water-soluble polymer and the water-soluble polymer content in the polishing composition. In other words, the weight average molecular weight of the water-soluble polymer is A, the content of the water-soluble polymer in the polishing composition [% by mass] is B, and the content of the dissolution inhibitor in the polishing composition [ppm by mass] When C is set to C, the value of C/(A × B) is within a specific range.

The weight average molecular weight A of the water-soluble polymer, the content B of the water-soluble polymer, and the content C of the dissolution inhibitor are respectively related to the ease with which the water-soluble polymer is uniformly dissolved in water.

As the weight average molecular weight A becomes larger, the number of hydration points of the hydroxyl group or the like contained in one molecule of the water-soluble polymer increases. As a result, to dissolve water solubility The amount of water required for the polymer is increased, and it is difficult to uniformly dissolve the water-soluble polymer in water. Therefore, the weight average molecular weight A of the water-soluble polymer can be said to be a parameter indicating difficulty in uniformly dissolving each molecule of the water-soluble polymer in water.

When the content B of the water-soluble polymer is large, the number of molecules of the water-soluble polymer in the polishing composition increases. Therefore, the larger the content B, the more the frequency of contact of the molecules of the water-soluble polymer in the polishing composition with each other. As a result, the molecules of the water-soluble polymer are easily complexed with each other, and it is difficult to uniformly dissolve the water-soluble polymer in water. Therefore, the content B of the water-soluble polymer can be said to be a parameter indicating the difficulty in uniformly dissolving the entire water-soluble polymer in the polishing composition in water.

Therefore, the product of the weight average molecular weight A of the water-soluble polymer and the content B of the water-soluble polymer (that is, A × B) is a comprehensive parameter indicating the difficulty in uniformly dissolving the water-soluble polymer in the polishing composition in water. The larger the value, the more difficult it is to dissolve the water-soluble polymer uniformly in water.

On the other hand, when the content C of the dissolution inhibitor is large, the number of molecules of the dissolution inhibitor in the polishing composition increases. Therefore, the larger the content C, the more the dissolution inhibitor acts on the more hydration points in the water-soluble polymer. As a result, the action of the hydration point of the water-soluble polymer is suppressed, and it becomes easy to uniformly dissolve the water-soluble polymer in water. Therefore, C/(A × B) can be said to be a parameter indicating the ratio between the difficulty in uniformly dissolving the water-soluble polymer in the polishing composition in water and the magnitude of the effect of the dissolution inhibitor on reducing the difficulty. The larger the value, the easier the water-soluble polymer is uniformly dissolved in water.

The value of C/(A × B) is preferably 2.5 × 10 ^-3 or more, more preferably 3.0 × 10 ^-3 or more, still more preferably 3.5 × 10 ^-3 or more, and most preferably 4.0 × 10 ^-3 or more. As the value of C/(A×B) increases, it becomes easy to dissolve the water-soluble polymer uniformly in water, and as a result, the number of particles adhering to the surface of the polished ruthenium substrate is reduced.

On the other hand, however, when the value of C/(A × B) is too large, the problem of an increase in the number of particles adhering to the surface of the ruthenium substrate after polishing also occurs. This is considered to be because the dissolution inhibitor present in excess with respect to the water-soluble polymer adheres to the surface of the ruthenium substrate. Therefore, the value of C/(A × B) is preferably 70 × 10 ^-3 or less, more preferably 30 × 10 ^-3 or less, still more preferably 20 × 10 ^-3 or less, and even more preferably 10 × 10 ^{- 3} or less, preferably 6.0 × 10 ^-3 or less. As the value of C/(A×B) decreases, the number of particles due to adhesion of the dissolution inhibitor to the surface of the polished ruthenium substrate decreases.

Further, the content of the dissolution inhibitor C and the value of C/(A × B) can be adjusted by changing the amount of the dissolution inhibitor added to the surface-treated water-soluble polymer used for preparation of the polishing composition. The content C of the dissolution inhibitor in the polishing composition can be measured as the amount of the dissolution inhibitor of the hydrolyzate of the surface-treated water-soluble polymer contained in the polishing composition and the like. When the dissolution inhibitor added to the surface of the water-soluble polymer has a different chemical structure from the hydrolyzate, the content C of the dissolution inhibitor can be calculated by converting the measured value of the amount of the hydrolyzate into a dissolution inhibitor. The amount of the above hydrolyzate contained in the polishing composition can be determined, for example, by using a high speed liquid chromatograph or a siphon electrophoresis apparatus.

(abrasive grain)

The polishing composition may contain abrasive grains. The abrasive grain system functions to physically polish the surface of the substrate.

Examples of the abrasive grains include inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include, for example, particles made of a metal oxide such as cerium oxide, aluminum oxide, cerium oxide, or titanium oxide, and cerium nitride particles, cerium carbide particles, and boron nitride particles. Specific examples of the organic particles are, for example, polymethyl methacrylate (PMMA) particles.

Among these specific examples, cerium oxide is preferred. Specific examples of the cerium oxide are colloidal cerium oxide, fumed cerium oxide, and sol-gel cerium oxide. Among these, colloidal cerium oxide and fumed cerium oxide are preferred, and colloidal cerium oxide is preferred from the viewpoint of reducing scratches on the surface of the substrate after polishing. These cerium oxides may be used alone or in combination of two or more.

The true specific gravity of the cerium oxide used is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more. As the true specific gravity of the cerium oxide increases, a high polishing rate when the ruthenium substrate is polished is obtained. The true specific gravity of cerium oxide is preferably 2.2 or less, more preferably 2.0 or less, and still more preferably 1.9 or less. As the true specific gravity of the cerium oxide is reduced, the surface quality of the ruthenium substrate after polishing is improved, and the degree of haze is specifically improved. The true specific gravity of cerium oxide is calculated from the weight of the dried cerium oxide particles and the total weight of the cerium oxide particles immersed in a known volume of ethanol.

The average primary particle diameter of the abrasive grains is preferably 5 nm or more, more preferably 10 nm or more, and still more preferably 20 nm or more. As the average primary particle size of the abrasive particles increases, a high polishing rate when the ruthenium substrate is polished is obtained. Abrasive grain The primary primary particle diameter is preferably 100 nm or less, more preferably 70 nm or less, and still more preferably 50 nm or less. As the average primary particle size of the abrasive particles decreases, the stability of the polishing composition is improved.

The value of the average primary particle diameter of the abrasive grains is calculated, for example, from the specific surface area measured by the BET method. The specific surface area measurement of the abrasive grains can be carried out using, for example, "Flow Sorb II 2300" manufactured by Micromeritics.

The average secondary particle diameter of the abrasive grains is preferably 10 nm or more, more preferably 20 nm or more, and still more preferably 30 nm or more. As the average secondary particle diameter of the abrasive grains increases, a high polishing speed at the time of polishing the ruthenium substrate is obtained. The average secondary particle diameter of the abrasive grains is preferably 200 nm or less, more preferably 150 nm or less, still more preferably 100 nm or less. As the average secondary particle size of the abrasive particles decreases, the stability of the polishing composition is improved. The average secondary particle diameter of the abrasive grains can be measured by a dynamic light scattering method using, for example, FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.

The average value of the long diameter/short diameter ratio of the abrasive grains is preferably 1.0 or more, more preferably 1.05 or more, still more preferably 1.1 or more. As the average value of the above-described long diameter/short diameter ratio increases, a high polishing rate at the time of polishing the ruthenium substrate is obtained. The average value of the long diameter/short diameter ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, still more preferably 1.5 or less. As the average value of the long diameter/short diameter ratio decreases, the scratch generated on the surface of the substrate after polishing is reduced.

The value of the long diameter/short diameter ratio and the shape of the abrasive grains can be determined by, for example, an electron microscope image of the abrasive grains. Specifically, a minimum rectangle of the tangential line of each abrasive grain in a scanning electron microscope image of a specific number (for example, 200) of abrasive grains is drawn. Next, calculate each rectangle The length of the long side (the value of the long diameter) is divided by the value of the short side length (the value of the short diameter) of the same rectangle, and the average value of the long diameter/short diameter ratio can be obtained by calculating the average value of the same.

The content of the abrasive grains in the polishing composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and still more preferably 0.3% by mass or more. As the abrasive grain content increases, a high polishing speed at the time of polishing the ruthenium substrate is obtained. The content of the abrasive grains in the polishing composition is preferably 10% by mass or less, more preferably 5% by mass or less, still more preferably 3% by mass or less, and most preferably 1% by mass or less. As the content of the abrasive particles is reduced, the stability of the polishing composition is improved.

(alkaline compound)

The polishing composition may contain a basic compound. The basic compound functions to chemically polish the surface of the substrate (chemical etching). Thereby, it is easy to improve the polishing rate of the substrate by the polishing composition.

Specific examples of the basic compound are exemplified by hydroxides or salts of alkali metals, quaternary ammonium hydroxide or salts thereof, ammonia, amines and the like. Specific examples of the alkali metal are exemplified by potassium, sodium, and the like. Specific examples of the salt are exemplified by carbonate, hydrogencarbonate, sulfate, acetate, and the like. Specific examples of the quaternary ammonium are exemplified by tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like. Specific examples of the hydroxide or salt of the alkali metal include potassium hydroxide, potassium carbonate, potassium hydrogencarbonate, potassium sulfate, potassium acetate, potassium chloride and the like. Specific examples of the quaternary ammonium hydroxide or a salt thereof are tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide and the like. Specific examples of the amine are exemplified by methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, and B. Diamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, di-ethyltriamine, tri-ethyltetramine, anhydrous piperidine, piperidine hexahydrate, 1 -(2-Aminoethyl)piperidine, N-methylpiperidine, hydrazine, and the like. These basic compounds may be used alone or in combination of two or more.

Among the basic compounds, at least one selected from the group consisting of ammonia, an ammonium salt, an alkali metal hydroxide, an alkali metal salt, and a quaternary ammonium hydroxide is preferred. More preferably, the basic compound is selected from the group consisting of ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, sodium hydrogencarbonate, ammonium carbonate, potassium hydrogencarbonate, potassium carbonate, and hydrogencarbonate. At least one of sodium and sodium carbonate is more preferably at least one selected from the group consisting of ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide, more preferably ammonia and tetramethylammonium hydroxide. One of the less ammonium, preferably ammonia.

The content of the basic compound in the polishing composition is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, and still more preferably 0.003% by mass or more. As the content of the basic compound in the polishing composition is increased, a high polishing rate at the time of polishing the ruthenium substrate is obtained. The content of the basic compound in the polishing composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less, and most preferably 0.1% by mass or less. As the content of the basic compound in the polishing composition is reduced, the shape of the ruthenium substrate is easily maintained.

The pH of the polishing composition is preferably 8.0 or more, more preferably 8.5 or more, still more preferably 9.0 or more. As the pH of the polishing composition increases, a high polishing rate at the time of polishing the ruthenium substrate is obtained. The pH of the polishing composition is preferably 12.5 or less, more preferably 12.0 or less, still more preferably 11.5 or less. With research The pH of the grinding composition is reduced, and the shape of the crucible substrate is easily maintained.

(chelating agent)

The polishing composition may contain a chelating agent. The chelating agent functions to suppress metal contamination of the ruthenium substrate by capturing metal impurities in the polishing system and forming a complex.

Specific examples of the chelating agent include, for example, an aminocarboxylic acid-based chelating agent and an organic phosphonic acid-based chelating agent. Specific examples of the aminocarboxylic acid-based chelating agent include ethylenediaminetetraacetic acid, sodium edetate, nitrilo triacetic acid, sodium nitrotriacetate, ammonium oxytriacetate, and hydroxyethyl acetonitrile. Amine triacetic acid, sodium hydroxyethyl ethylenediamine triacetate, diethylidene triamine pentaacetic acid, sodium diethylammonium pentaacetate, triethylammonium hexaacetate, triethylammonium hexaacetate Sodium and so on. Specific examples of the organic phosphonic acid-based chelating agent are 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotris(ethylphosphonic acid), and ethylenediamine.肆 (methylene phosphonic acid), di-ethyltriamine penta (methylene phosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane 1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methane hydroxyl Phosphonic acid, 2-phosphonium butane-1,2-dicarboxylic acid, 1-phosphonium butane-2,3,4-tricarboxylic acid, α-methylphosphonium succinic acid and the like. Among these, an organic phosphonic acid-based chelating agent is preferred, and ethylenediamine oxime (methylene phosphonic acid) is preferred. These chelating agents may be used alone or in combination of two or more.

(surfactant)

The polishing composition may contain a surfactant. The surfactant acts to suppress the roughness of the polished surface of the ruthenium substrate. Thereby, the degree of haze of the substrate surface after polishing can be easily reduced. In particular, when the polishing composition contains a basic compound, it is likely to be roughened on the surface of the substrate after polishing by chemical etching by the alkaline compound. Therefore, the use of a basic compound in combination with a surfactant is particularly effective.

The weight average molecular weight of the surfactant is preferably less than 1,000. The surfactant can be anionic or nonionic. Among them, a nonionic surfactant is preferred. Since the non-separating surfactant has low foaming property, workability at the time of preparation of the polishing composition or at the time of use becomes easy. Further, when a nonionic surfactant is used, pH adjustment of the polishing composition is facilitated.

Specific examples of the nonionic surfactant are exemplified by a homopolymer of an oxyalkylene group, a copolymer of a plurality of kinds of oxyalkylene groups, and a polyoxyalkylene alkyl adduct. Specific examples of the homopolymer of the oxyalkylene group are polyoxyethylene ethyl, polyethylene glycol, polyoxypropylidene and polyoxybutylene. Specific examples of the copolymer of a plurality of oxyalkylene groups are polyoxyethylene ethyl oxypropylene glycol and polyoxyethylene polyoxybutylene glycol.

Specific examples of the polyoxyalkylene alkyl adduct are polyoxyethylene ethyl ether, polyoxyethylidene ether, polyoxyethylene alkylamine, polyoxyethyl alcohol ester , polyoxyethylene glycol ether fatty acid ester, polyoxyethylene ethyl sorbitan fatty acid ester and the like. More specifically, polyoxyethylene ethyl polyoxypropyl propylene copolymer, polyoxyethylene glycol, polyoxyethylene ethyl propyl ether, polyoxyethylene ethyl butyl ether, polyoxyethylene ethyl pentyl ether, Polyoxyethylene ethylhexyl ether, polyoxyethylene ethyl octyl ether, polyoxyethylene ethyl-2-ethylhexyl ether, polyoxyethyl ether Ether, polyoxyethylene ethyl decyl ether, polyoxyethylene ethyl isodecyl ether, polyoxyethylene ethyl tridecyl ether, polyoxyethylene ethyl lauryl ether, polyoxyethyl ether cetyl ether , polyoxyethylene ethyl stearyl ether, polyoxyethylene ethyl isostearyl ether, polyoxyethylene ethyl oleyl ether, polyoxyethyl phenyl ether, polyoxyethyl octyl phenyl ether , polyoxyethylidene phenyl ether, polyoxyethylene ethyl dodecyl phenyl ether, polyoxyethyl styrene ether, polyoxyethylene ethyl laurylamine, polyoxyethylene Stearylamine, polyoxyethylene ethyl oleylamine, polyoxyethylidene stearylamine, polyoxyethylene ethyl decylamine, polyoxyethylene ethyl laurate, polyoxyethylene Monostearate, polyoxyethylene ethyl distearate, polyoxyethylidene monooleate, polyoxyethylene ethyl oleate, polylaurate monoethyl sorbitan , monopalmitic acid polyoxyethylene ethyl sorbitan, monostearic acid polyoxyethylene ethyl sorbitan, monooleic acid polyoxyethylene ethyl sorbitan, trioleic acid polyoxyethylene ethyl sorbitol Sugar alcohol anhydride, tetraoleic acid polyoxyethylene ethyl sorbitol, polyoxyethylene Sesame oil, polyoxyethylene castor oil extending ethyl hard.

Among these nonionic surfactants, a copolymer of an alkyloxy group or a plurality of alkyloxy groups is preferred. In this case, it is easy to reduce the haze on the surface of the substrate after polishing to a level that is particularly suitable for practical use. The reason for this is considered to be that the slightly hydrophilic ether bond and the slightly hydrophobic alkyl group interact in the molecular chain of the polymers.

The ratio of the oxy-ethyl group in the homopolymer of the oxyalkylene group or the oxyalkylene group of the plurality of alkylene groups is preferably 85% by mass or more, more preferably 90% by mass or more. As the ratio of the oxygen-extended ethyl units in the polymer increases, the adhesion of the particles to the surface of the substrate after grinding is inhibited.

Non-ionic surfactant HLB (hydrophile-lipophile The balance, lipophilic-lipophilic balance value is preferably 17 or more, more preferably 18 or more. As the HLB value of the nonionic surfactant increases, the adhesion of the particles to the surface of the substrate after grinding is inhibited.

The surfactants may be used alone or in combination of two or more.

The content of the surfactant in the polishing composition is preferably 0.0001% by mass or more, more preferably 0.001% by mass or more. As the surfactant content increases, the degree of haze on the surface of the substrate after grinding is further reduced. The content of the surfactant in the polishing composition is preferably 0.05% by mass or less, more preferably 0.02% by mass or less. As the amount of surfactant is reduced, the adhesion of the particles to the surface of the substrate after grinding is inhibited.

(other ingredients)

The polishing composition may further contain a conventional additive generally contained in the polishing composition, such as an organic acid, an organic acid salt, an inorganic acid, a mineral acid salt, a preservative, an antifungal agent, or the like. For example, when any of an organic acid, an organic acid salt, an inorganic acid, and a mineral acid salt is added, the hydrophilicity of the surface of the ruthenium substrate after polishing can be improved by interaction with the water-soluble polymer.

Specific examples of the organic acid include fatty acids such as formic acid, acetic acid, and propionic acid, aromatic carboxylic acids such as benzoic acid and phthalic acid, citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, and organic compounds. Sulfonic acid, organic phosphonic acid, and the like. Specific examples of the organic acid salt are exemplified by alkali metal salts such as sodium salts and potassium salts of the organic acids, or ammonium salts.

Specific examples of the inorganic acid are sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, and the like. Specific examples of the inorganic acid salt are exemplified by an alkali metal salt such as a sodium salt or a potassium salt of the inorganic acid or an ammonium salt.

Among the organic acid salts and inorganic acid salts, an ammonium salt is preferred from the viewpoint of suppressing metal contamination of the tantalum substrate.

The organic acid and the salt thereof, and the inorganic acid and the salt thereof may be used alone or in combination of two or more.

Specific examples of the preservative and the antifungal agent include an isothiazoline compound, a paraben, a phenoxyethanol, and the like.

Next, a method of producing the polishing composition of the present embodiment will be described.

The polishing composition is prepared by a step of mixing a surface-treated water-soluble polymer (a water-soluble polymer having a surface-added dissolution inhibitor) in water to dissolve it. Further, other components such as abrasive grains may be further mixed in the polishing composition as needed.

The surface-treated water-soluble polymer mixed in water is first dispersed in water. Subsequently, the dispersed surface-treated water-soluble polymer is hydrolyzed by a stirring operation to produce a water-soluble polymer and a dissolution inhibitor, and these are dissolved in water. As a result, a polishing composition in which a water-soluble polymer and a dissolution inhibitor are dissolved in water is obtained. The amount of the water-soluble polymer to be surface-treated and the weight average molecular weight of the water-soluble polymer in the surface-treated water-soluble polymer and the addition amount of the dissolution inhibitor are such that the finally obtained polishing composition has the above specific range C The value of /(A×B) is selected.

The surface-treated water-soluble polymer is preferably finely divided from the viewpoint of uniform dispersion in water. Specifically, the surface treatment of the water-soluble polymer The particle size is preferably 1000 μm or less, more preferably 500 μm or less, and most preferably 200 μm or less. When the water-soluble polymer is surface-treated with a particle size within the above range, the surface-treated water-soluble polymer is easily and uniformly dispersed in water, so that a fine dispersion is obtained.

On the other hand, the particle size of the surface-treated water-soluble polymer is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 50 μm or more, still more preferably 90 μm or more, and most preferably 120 μm or more. When the water-soluble polymer is treated with the surface of the above particle size range, the adhesion of the particles to the surface of the substrate after polishing is further suppressed.

It is preferred to add a basic compound to a dispersion in which a surface-treated water-soluble polymer is dispersed in water, and to make the dispersion alkaline (for example, pH 8 or more and 12 or less). Afterwards. In this case, hydrolysis of the water-soluble polymer from the surface treatment into a water-soluble polymer and a dissolution inhibitor can be promoted, and the water-soluble polymer can be more appropriately dissolved.

Further, in order to uniformly disperse the surface-treated water-soluble polymer in water and uniformly dissolve the water-soluble polymer in water, it is preferred to contact the surface-treated water-soluble polymer solid particles with water as much as possible. It is possible to appropriately set the mixing speed or the dissolution time (that is, the stirring time) of the surface-treated water-soluble polymer.

The mixing speed of the surface-treated water-soluble polymer is preferably 0.01 g or more in 1 minute, more preferably 0.1 g or more, more preferably 1 g or more, and still more preferably 5 g or more. It is 10g or more. Moreover, the mixing speed of the surface-treated water-soluble polymer is better in 1 minute in terms of water 1L. It is 100 g or less, more preferably 70 g or less, still more preferably 50 g or less, and most preferably 30 g or less.

The dissolution time is preferably 1 hour or longer, more preferably 3 hours or longer, and most preferably 6 hours or longer. Further, the dissolution time is preferably 48 hours or shorter, more preferably 36 hours or shorter, and most preferably 24 hours or shorter.

As the agitator for mixing the surface-treated water-soluble polymer and water, for example, a vane type agitator, a homomixer, and a homogenizer can be used. When a vane type agitator is used, the rotation speed is preferably 100 rpm or more and 2000 rpm or less. When a homomixer or a homogenizer is used, the rotation speed is preferably from 1000 rpm to 10,000 rpm.

Next, a method of manufacturing a semiconductor substrate will be described.

The method for producing a semiconductor substrate has a step of polishing the surface of the ruthenium substrate using the polishing composition of the present embodiment. The polishing of the ruthenium substrate is performed by applying the polishing composition to the surface of the ruthenium substrate while pressing the polishing pad against the same surface to rotate the ruthenium substrate and the polishing pad. At this time, the surface of the crucible substrate is polished by the physical action generated by the friction between the polishing pad and the surface of the crucible substrate. When the polishing composition contains abrasive grains, the surface of the ruthenium substrate is polished by the physical action of friction between the abrasive grains and the surface of the ruthenium substrate. When the polishing composition contains a basic compound, in addition to the above physical effects, the surface of the ruthenium substrate is also polished by the chemical action of the basic compound.

According to the embodiment described above in detail, the following effects can be exhibited.

(1) A water-soluble polymer containing a solid raw material and a dissolution inhibitor and water which function to reduce the water dissolution rate of the water-soluble polymer. The weight average molecular weight of the water-soluble polymer is A, the content of the water-soluble polymer in the polishing composition [% by mass] is B, and the content of the dissolution inhibitor in the polishing composition [ppm] is set to In the case of C, the value of C/(A × B) is 70 × 10 ^-3 or less. Thereby, adhesion of the particles to the surface of the substrate after polishing can be suppressed.

(2) When the content of the dissolution inhibitor in the polishing composition is 80 ppm or less, the adhesion of particles due to the dissolution inhibitor is suppressed. Therefore, the adhesion of the particles to the surface of the substrate after polishing can be further suppressed.

(3) When the weight average molecular weight of the water-soluble polymer is 1,000,000 or less, the degree of haze on the surface of the substrate after polishing can be reduced.

(4) A substrate having a stable quality can be easily obtained by using the polishing composition in the use of polishing the ruthenium substrate, particularly in the final use of the ruthenium substrate.

(5) A method of manufacturing a semiconductor substrate, comprising the step of polishing a germanium substrate using the polishing composition described above. Thereby, a substrate of stable quality is formed, and a high-quality semiconductor substrate can be manufactured from the same substrate.

Further, the above embodiment may be modified as follows.

. The polishing composition of the above embodiment may be in one dosage form or in a multi-dosage form represented by two dosage forms.

. The polishing composition of the above embodiment may be in a concentrated state at the time of production and at the time of sale. That is, the polishing composition of the above embodiment can be produced and sold in the form of a stock solution of the polishing composition.

. The polishing composition of the above embodiment can also be prepared by diluting a stock solution of the polishing composition with water. The dilution ratio in this case is preferably 2 times or more, more preferably 5 times or more, and still more preferably 10 times or more. With the above thin The release ratio is increased, the raw liquid transportation cost of the polishing composition becomes cheaper, and the storage place can be saved. The above dilution ratio is preferably 100 times or less, more preferably 50 times or less, and still more preferably 40 times or less. As the above dilution ratio decreases, the stability of the polishing composition stock solution can be improved.

. Each component contained in the polishing composition of the above embodiment can be filtered by a filter before the polishing composition is manufactured. The polishing composition of the above embodiment may be filtered by a filter just before use. By applying a filtration treatment, coarse foreign matter in the polishing composition is removed, and the quality of the polishing composition is improved.

The material and structure of the filter used in the above filtration treatment are not particularly limited. The material of the filter is exemplified by, for example, cellulose, nylon, polyfluorene, polyether oxime, polypropylene, polytetrafluoroethylene (PTFE), polycarbonate, glass, and the like. The configuration of the filter is exemplified by, for example, depth filters, pleats filters, membrane filters, and the like.

. The polishing pad used in polishing the ruthenium substrate using the polishing composition of the above embodiment is not particularly limited. Any of the types of polishing pads, such as non-woven fabrics, suede, abrasive-containing types, and abrasive-free particles, can be used.

. When the ruthenium substrate is polished by using the polishing composition of the above embodiment, the used polishing composition can be recovered and used for polishing the ruthenium substrate. Further, the method of using the polishing composition is, for example, a method in which the used polishing composition discharged from the polishing apparatus is collected in a tank and recycled from the tank to the polishing apparatus. By using the polishing composition again, the amount of the polishing composition treated as the waste liquid can be reduced and reduced The amount of the composition used for grinding is small. This makes it possible to reduce the environmental load and to suppress the polishing cost of the substrate.

When the polishing composition is used again, each component such as a water-soluble polymer is consumed and lost by polishing. Therefore, it is preferred to supplement the amount of reduction of each component such as a water-soluble polymer to the polishing composition. The components to be added may be separately added to the polishing composition, or may be added to the polishing composition at a concentration of a mixture containing two or more components depending on the size of the tank or the polishing conditions. By supplementing the amount of reduction of each component with the polishing composition to be used, the composition of the polishing composition can be maintained, and the function of the polishing composition can be continuously exhibited.

. The polishing composition of the above embodiment can also be used for applications other than polishing a ruthenium substrate. For example, it is also possible to obtain an abrasive article made of metal such as stainless steel, plastic, glass, and sapphire.

Next, the technical idea that can be grasped by the above embodiment will be described.

(A) a polishing composition obtained by adding a dissolution inhibitor to a surface of a water-soluble polymer of a solid raw material, and preparing a surface-treated water-soluble polymer and water having a reduced water dissolution rate, and containing the foregoing A water soluble polymer and the aforementioned dissolution inhibitor.

[Examples]

The surface-treated water-soluble polymer obtained by adding oxalic acid dialdehyde (dissolution inhibitor) to the surface of hydroxyethyl cellulose (water-soluble polymer) was mixed in ion-exchanged water under the conditions shown in Table 1, Modulation of hydroxyl groups A mixture of Examples 1 to 45 and Comparative Example 1 of ethyl cellulose and oxalic acid dialdehyde. The weight average molecular weight of the hydroxyethyl cellulose of the surface-treated water-soluble polymer and the amount of addition of oxalic acid dialdehyde are various. Further, a mixture of Comparative Example 2 containing hydroxyethylcellulose was prepared by directly mixing hydroxyethylcellulose in ion-exchanged water under the conditions shown in Table 1.

Next, colloidal cerium oxide (abrasive grains) having an average primary particle diameter of 35 nm and ammonia (basic compound) and ion-exchanged water were mixed in each of the above mixed liquids to prepare polishing of Examples 1 to 45 and Comparative Examples 1 and 2. Use the composition. The common composition of each polishing composition is shown in Table 2. The content of hydroxyethylcellulose and oxalic acid dialdehyde in each polishing composition and the weight average molecular weight of hydroxyethylcellulose in each polishing composition are shown in Table 4. The content of oxalic acid dialdehyde in the polishing composition was measured using a high speed liquid chromatograph. The content of the hydroxyethylcellulose in the polishing composition was calculated based on the amount of the surface-treated water-soluble polymer used and the content of oxalic acid dialdehyde in the polishing composition.

Next, using the respective polishing compositions, the surface of the pre-polished ruthenium substrate was finally polished under the conditions described in Table 3. After use, the substrate diameter is 300mm, the conductivity type is P type, the crystal orientation is <100>, and the resistivity is 0.1Ω. Above cm and 100Ω. The pre-grinding was carried out using a polishing slurry (trade name: GLANZOX 1103) manufactured by FUJIMI Incorperated Co., Ltd.. Next, the ruthenium substrate after final polishing using each polishing composition was evaluated for the degree of granules and haze.

(evaluation of particles)

The wafer inspection apparatus "Surfscan SP2" manufactured by KLA Tencor Co., Ltd. was used to measure the number of particles having a size of 37 nm or more present on the surface of the substrate after polishing. The results are shown in the "Particles" column of Table 4. The "A" shown in the "Particles" column of Table 4 indicates that the number of particles is less than 100, "B" indicates 100 or more and less than 120, and "C" indicates 120 or more and less than 140, " D" indicates 140 or more and less than 160, "E" indicates 160 or more and less than 200, "F" indicates 200 or more and less than 300, and "G" indicates 300 or more.

(Evaluation of fogging degree)

The wafer inspection apparatus "Surfscan SP2" manufactured by KLA Tencor Co., Ltd. was used to evaluate the degree of haze on the same surface based on the measured value obtained by measuring the surface of the polished tantalum substrate in the DWO mode of the same apparatus. The results are shown in the column of "degree of haze" in Table 4. "A" shown in the column of "degree of haze" in Table 4 indicates that the measured value is less than 0.11 ppm, "B" indicates 0.11 ppm or more and less than 0.12 ppm, and "C" indicates 0.12 ppm or more and less than 0.13 ppm.

As shown in Table 4, when the polishing compositions of Examples 1 to 45 and Comparative Example 1 containing a water-soluble polymer and a dissolution inhibitor were used, the polishing composition of Comparative Example 2 containing no dissolution inhibitor was used. At the time, the number of particles measured was small. Further, when the polishing composition of Examples 1 to 45 having a C/(A × B) value of 70 × 10 ^-3 or less was used, the value exceeding C × (A × B) was more than 70 × 10 ^{- In} the case of the polishing composition of Comparative Example 1, the number of particles measured was smaller. The results show that the polishing composition is prepared such that the weight average molecular weight (A) of the water-soluble polymer, the content (B) of the water-soluble polymer, and the content (C) of the dissolution inhibitor satisfy a specific relationship. It can effectively inhibit the adhesion of the particles to the surface of the substrate after grinding.

Claims (7)

A polishing composition characterized by comprising a water-soluble polymer of a solid raw material, a dissolution inhibitor which functions to reduce water solubility of the water-soluble polymer, and water, and setting a weight average molecular weight of the water-soluble polymer In the case where A, the content of the water-soluble polymer in the polishing composition is [% by mass], B, and the content of the dissolution inhibitor in the polishing composition [mass ppm] is C, C/(A × The value of B) is 70 × 10 ^-3 or less. The polishing composition according to claim 1, wherein the content of the dissolution inhibitor in the polishing composition is 80 ppm by mass or less. The polishing composition according to claim 1 or 2, wherein the water-soluble polymer has a weight average molecular weight of 1,000,000 or less. The polishing composition of claim 1 or 2, which is used for polishing a ruthenium substrate. The polishing composition of claim 4, which is used for the final polishing of the ruthenium substrate. A method for producing a polishing composition according to claim 1, wherein the method for producing a polishing composition according to claim 1 or 2 is characterized in that: surface treatment for adding the dissolution inhibitor to the surface of the water-soluble polymer is provided The step of mixing the water-soluble polymer in water and dissolving. A method of producing a semiconductor substrate, comprising the step of polishing a ruthenium substrate using the polishing composition of claim 1 or 2.