JP2017114966A - Composition for chemical mechanical polishing and chemical mechanical polishing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersant for chemical mechanical polishing capable of being polished at high removal speed in a polishing application of polysilicon or amorphous silicon and a chemical mechanical polishing method using the same.SOLUTION: There is provided a composition for chemical mechanical polishing contains a polymer (A) having a repeating unit having a sulfinyl group in a side chain and the repeating unit having the sulfinyl group in the side chain is represented by the following formula (1). (1), where Rrepresents a direct bond or a bivalent organic group having 1 to 24 carbon atoms, Rrepresents an alkanediyl group having 1 to 20 carbon atoms, which may have a substituent or an arylene group having 6 to 20 carbon atoms, which may have a substituent.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous dispersion for chemical mechanical polishing and a chemical mechanical polishing method using the same.

  In the manufacturing process of a semiconductor device, there is a polishing process for removing at least a part of single silicon such as amorphous silicon and polysilicon. Such polishing is performed using an alkaline polishing composition as described in Patent Documents 1 and 2. In the acidic to neutral region, a polishing composition to which a polysaccharide, polycarboxylic acid or the like is added is also used (Patent Document 3).

Japanese translation of PCT publication No. 2002-525383 Japanese Patent No. 5695708 Japanese Patent No. 5695708

  However, many of the previously known polishing compositions described above are not capable of polishing a silicon material at a high removal rate that sufficiently satisfies user requirements.

  Accordingly, some aspects of the present invention provide a chemical mechanical polishing aqueous dispersion capable of polishing at a high removal rate in polishing applications of polysilicon or amorphous silicon by solving the above-described problems, and A chemical mechanical polishing method using the same is provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the chemical mechanical polishing composition according to the present invention is:
It contains a compound having a sulfinyl group.

[Application Example 2]
In the above application example,
The compound contains a polymer (A) having a repeating unit having a sulfinyl group in the side chain.

[Application Example 3]
In the above application example,
The repeating unit having the sulfinyl group in the side chain can be represented by the following general formula (1).

(1)
(In General Formula (1), R ³ represents a direct bond or a divalent organic group having 1 to 24 carbon atoms, and R ⁴ represents an alkyl group having 1 to 20 carbon atoms which may have a substituent or a substituted group. An aryl group having 6 to 20 carbon atoms which may have a group is shown.)
[Application Example 4]
In the above application example,
The repeating unit having the sulfinyl group in the side chain can be represented by the following general formula (2).

(2)
(In General Formula (2), each R ¹ independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ² represents a direct bond, —O—, * — (C═O) —O—, * ^{- (C = O) -NR 6} -, * - NR 6 - (C = O) - (R 6 is a hydrogen atom or an organic group having 1 to 10 carbon atoms, * the general formula (2) R ¹ represents a position bonded to the carbon atom to which R ¹ is bonded) or a phenylene group, R ⁵ represents a hydrogen atom or —OR ⁷ (R ⁷ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms) R ⁸ represents each independently a direct bond or a C1-C10 alkanediyl group which may have a substituent, and R ³ and R ⁴ are as defined above.
[Application Example 5]
In the above application example,
The polymer (A) may further have a repeating unit derived from one or more monomers selected from conjugated dienes, styrenes, (meth) acrylates, and (meth) acrylamides.

[Application Example 6]
In the above application example,
A silicon material can be included in the surface to be polished.

[Application Example 7]
One aspect of the polishing method according to the present invention is:
It includes a step of polishing a wiring substrate containing a silicon material using the chemical mechanical polishing composition described in any one of Application Examples 1 to 6.

  Among the substrates constituting semiconductor devices, it is known that the surface of silicon nitride is positively charged during chemical mechanical polishing, and the surface of silicon oxide is negatively charged during chemical mechanical polishing. ing. Therefore, according to the chemical mechanical polishing aqueous dispersion according to the present invention, it is possible to selectively polish a positively charged substrate (for example, a silicon nitride film) during chemical mechanical polishing due to the high polarity of the sulfinyl group. it can.

It is sectional drawing which showed typically the to-be-processed object suitable for use of the chemical mechanical polishing method which concerns on this Embodiment. It is sectional drawing which showed typically the to-be-processed object at the time of completion | finish of a 1st grinding | polishing process. It is sectional drawing which showed typically the to-be-processed object at the time of completion | finish of a 2nd grinding | polishing process. It is the perspective view which showed the chemical mechanical polishing apparatus typically. It is sectional drawing which showed typically the to-be-processed object used by the experiment example.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, Various modifications implemented in the range which does not change the summary of this invention are also included.

1. Chemical mechanical polishing composition The chemical mechanical polishing composition according to one embodiment of the invention contains a compound having a sulfinyl group. Examples of the compound having a sulfinyl group include a low molecular compound and a polymer. Among these, a polymer is preferable, and a polymer having a sulfinyl group in the side chain is particularly preferable.

  Hereinafter, each component contained in the chemical mechanical polishing composition according to the present embodiment will be described.

1.1. Polymer having sulfinyl group in side chain (A)
The chemical mechanical polishing composition according to this embodiment contains a polymer (A) having a sulfinyl group in the side chain. Since the polymer (A) has the ability to adsorb on the surface of simple silicon such as amorphous silicon and polysilicon, the addition of the polymer (A) forms a polymer layer on the surface and greatly improves the wettability. This promotes interaction with the abrasive grains.

Preferable specific examples of the polymer (A) having a sulfinyl group in the side chain include a repeating unit containing at least one structure represented by the following general formula (1) in the side chain. As the polymer species serving as a repeating unit having a structure represented by) in the side chain, known polymers can be used. More specifically, a repeating unit represented by the following general formula (2) can be exemplified. In the general formula (1) or (2), part of the sulfinyl group may be sulfide (—S—) or sulfone (—SO ₂ —).

(1)
(In General Formula (1), R ³ represents a direct bond or a divalent organic group having 1 to 24 carbon atoms, and R ⁴ represents an alkyl group having 1 to 20 carbon atoms which may have a substituent or a substituted group. An aryl group having 6 to 20 carbon atoms which may have a group is shown.)

(2)
(In General Formula (2), each R ¹ independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ² represents a direct bond, —O—, * — (C═O) —O—, * ^{- (C = O) -NR 6} -, * - NR 6 - (C = O) - (R 6 is a hydrogen atom or an organic group having 1 to 10 carbon atoms, * the general formula (2) R ¹ represents a position bonded to the carbon atom to which R ¹ is bonded) or a phenylene group, R ⁵ represents a hydrogen atom or —OR ⁷ (R ⁷ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms) R ⁸ represents each independently a direct bond or a C1-C10 alkanediyl group which may have a substituent, and R ³ and R ⁴ are as defined above.
R ¹ in the general formula (2) represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom or a methyl group.

^{R 2} is a direct bond in formula (2) in, -O -, * - (C = O) -O -, * - (C = O) -NR 6 -, * - NR 6 - (C = O )-(R ⁶ represents a hydrogen atom or an organic group having 1 to 10 carbon atoms, * represents a position bonded to the carbon atom to which R ¹ in the general formula (2) is bonded) or a phenylene group Indicates. Examples of the phenylene group include a 1,2-phenylene group, a 1,3-phenylene group, and a 1,4-phenylene group. Among these, a direct bond or a phenylene group is preferable.

The number of carbon atoms of the organic group represented by the ^{R 6} is preferably 1 to 10, more preferably from 2 to 8, more preferably from 2 to 6. As said organic group, a hydrocarbon group is mentioned, for example. Such a hydrocarbon group is a concept including an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group.

R ³ in the general formulas (1) and (2) represents a direct bond or a divalent organic group having 1 to 24 carbon atoms, and examples of the divalent organic group include a divalent hydrocarbon group. The divalent hydrocarbon group is preferably a divalent aliphatic hydrocarbon group and may be linear or branched. Specifically, methane-1,1-diyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, Propane-1,3-diyl group, propane-2,2-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,4 -Diyl group, pentane-1,5-diyl group, hexane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, etc. An alkanediyl group may be mentioned.

R ⁴ in the above general formulas (1) and (2) is an optionally substituted alkyl group having 1 to 20 carbon atoms or an optionally substituted aryl group having 6 to 20 carbon atoms. Indicates.

  Examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and an isobutyl group. Carbon number of an alkyl group becomes like this. Preferably it is 1-15, More preferably, it is 1-10. Examples of the aryl group having 6 to 20 carbon atoms include phenyl group, 1-naphthyl group, 2-naphthyl group and the like. Carbon number of an aryl group becomes like this. Preferably it is 6-18, More preferably, it is 6-15.

Examples of the substituent in R ⁴ include a hydroxyl group, a carboxyl group, a sulfonic acid group, an amide group, and an amino group, and among these, a hydroxyl group is particularly preferable.

In particular, R ⁴ preferably contains a monovalent group represented by the following general formula (3).

(3)
In said general formula (3), a is an integer of 0-4, Preferably it is an integer of 0-1.

The repeating unit (1) in the polymer (A) is usually 20 mol% or more, preferably 20 to 90 mol%, more preferably 30 to 80 mol in 100 mol% of all repeating units constituting the polymer (A). %. When the content of the repeating unit (1) is in the above range, a protective layer made of a polymer tends to be easily formed on the metal surface.
R < ⁸ > shows the C1-C10 alkenyl group which may have a direct bond or a substituent each independently. Specifically, methane-1,1-diyl group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,1-diyl group, propane-1,2-diyl group, Propane-1,3-diyl group, propane-2,2-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, pentane-1,4 -Diyl group, pentane-1,5-diyl group, hexane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, etc. Can be mentioned.
Examples of the substituent include a hydroxyl group, a carboxyl group, a sulfonic acid group, an amide group, and an amino group, as in the substituent for R ⁴ .

  The polymer (A) may further have a repeating unit derived from one or more monomers selected from a conjugated diene series, a styrene series, a (meth) acrylate series and a (meth) acrylamide series. These repeating units may be used alone or in combination of two or more.

  Examples of the conjugated diene-based repeating unit include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 2-methyl. Examples include -1,3-pentadiene, 1,3-hexadiene, 1,3-octadiene, 3-butyl-1,3-octadiene, and 4,5-diethyl-1,3-octadiene. Of these, 1,3-butadiene and isoprene are preferred. A conjugated diene compound may be used individually by 1 type, and may use 2 or more types together.

  Specific examples of the repeating unit derived from styrenes include styrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,4,6-trimethylstyrene, 4-ethylstyrene, 4-isopropylstyrene, 4-tert. -Repeating units derived from butylstyrene, α-methylstyrene and the like.

Examples of the (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. (Meth) acrylic acid C _1-15 alkyl; (meth) acrylic acid cyclohexyl C _6-10 cycloalkyl; (meth) acrylic acid 1-methoxyethyl, (meth) acrylic acid 2-methoxy (Meth) acrylic acid C _1-10 alkoxy C _1-10 alkyl such as ethyl; (meth) acrylic acid 1-adamantyl, (meth) acrylic acid 1-methyl- (1-adamantylethyl), (meth) acrylic acid tricyclo [5.2.1.0 ^{2, 6]} having a bridged ring hydrocarbon group having 8 to 16 carbon atoms such as decane-8-yl ( Data), and acrylic acid esters. In these (meth) acrylates, the C _1-10 alkyl group is preferably a C _1-8 alkyl group, the C _6-10 cycloalkyl group is preferably a C _6-8 cycloalkyl group, and the C _{As the 1-10} alkoxy group, a C _1-6 alkoxy group is preferable, and as the bridged ring hydrocarbon group having 8 to 16 carbon atoms, a bridged ring hydrocarbon group having 8 to 12 carbon atoms is preferable.

Examples of the (meth) acrylamides include N, N-diC _1-10 alkyl (meth) acrylamide; N—C _1-10 alkyl (meth) acrylamide such as N-isopropyl (meth) acrylamide; N In addition to N-C _1-10 alkanoyl C _1-10 alkyl (meth) acrylamide such as-(1,1-dimethyl-2-acetylethyl) (meth) acrylamide, (meth) acryloylpiperidine and the like can be mentioned. In these (meth) acrylamides, the C _1-10 alkyl group is preferably a C _3-10 alkyl group, and the C _1-10 alkanoyl group is preferably a C _1-6 alkanoyl group.

  The weight average molecular weight (Mw) of the polymer (A) is preferably from 1,000 to 1,500,000, more preferably from 3,000 to 1,000,000, and even more preferably from 5,000 to 500,000. Moreover, the molecular weight distribution represented by the weight average molecular weight (Mw) / number average molecular weight (Mn) of the polymer (A) used in the present embodiment is usually 1 to 5, preferably 1.1 to 3, more preferably. Is 1.2-2. In the present specification, “weight average molecular weight” refers to a weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

  The repeating unit derived from one or more monomers selected from conjugated diene-based, styrene-based, (meth) acrylate-based, and (meth) acrylamide-based polymers in the polymer (A) constitutes the polymer (A). In 100 mol% of all repeating units, it is usually 5 mol% or more, preferably 10 mol% or more, more preferably 15 mol% or more. When the content of the repeating unit is in the above range, excessive etching tends to be easily prevented.

  In the chemical mechanical polishing composition according to this embodiment, the content ratio of the polymer (A) is preferably 0.0001% by mass or more and 1% by mass with respect to the total mass (100% by mass) of the cleaning composition. Hereinafter, it is more preferably 0.0005 mass% or more and 0.5 mass% or less, and particularly preferably 0.001 mass% or more and 0.1 mass% or less. When the content ratio of the polymer (A) is within the above range, the polymer can be prevented from remaining on the surface of the wiring material while being sufficiently adsorbed on the surface of a single silicon such as amorphous silicon or polysilicon. In addition, a good wiring material surface can be obtained without excessive etching.

1.2. Other Components Abrasive grains, oxidizing agents, surfactants, water-soluble polymers, anticorrosives, and the like can be added to the cleaning composition according to the present embodiment as necessary.

1.2.1. (C) Abrasive Grain The chemical mechanical polishing composition according to the present embodiment further contains (C) an abrasive grain. (C) As an abrasive grain, inorganic particles, such as a silica, a ceria, an alumina, a zirconia, a titania, are mentioned, for example.

  Examples of the silica particles include colloidal silica and fumed silica. Among these, colloidal silica is preferably used. Colloidal silica is preferably used from the viewpoint of reducing polishing defects such as scratches, and for example, those produced by the method described in JP-A-2003-109921 can be used. Also, JP 2010-269985A, J. Org. Ind. Eng. Chem. , Vol. 12, no. 6, (2006) 911-917 or the like, surface-modified colloidal silica may be used.

  In particular, cationically modified colloidal silica having a cationic group introduced on the surface of colloidal silica is excellent in stability under acidic conditions, and thus is preferably used in the present invention. Examples of the method for introducing a cationic group on the surface of colloidal silica include a method for modifying a silane coupling agent having a functional group that can be chemically converted into a cationic group on the surface of colloidal silica. As such silane coupling agents, aminopropyltrimethoxysilane, (aminoethyl) aminopropyltrimethoxysilane, aminopropyltriethoxysilane, aminopropyldimethylethoxysilane, aminopropylmethyldiethoxysilane, aminobutyltriethoxysilane Etc.

  Moreover, you may use the sulfonic acid modification colloidal silica by which the sulfonic acid group was introduce | transduced into the surface of colloidal silica. As a method for introducing a sulfonic acid group to the surface of colloidal silica, a silane coupling agent having a functional group that can be chemically converted to a sulfonic acid group is modified on the surface of colloidal silica, and then the functional group is converted to a sulfonic acid group. The method of converting into is mentioned. Examples of such silane coupling agents include silane coupling agents having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; bis (3-triethoxy And silane coupling agents having a sulfide group such as (silylpropyl) disulfide. It can be converted into a sulfonic acid group by oxidizing the mercapto group or sulfide group of the silane coupling agent modified on the surface of the colloidal silica.

  (C) The content ratio of the abrasive grains is 0.1% by mass or more and 10% by mass or less, preferably 0.3% by mass or more and 8% by mass or less, more preferably based on the total mass of the chemical mechanical polishing composition. It is 0.5 mass% or more and 5 mass% or less. (C) When the content ratio of the abrasive grains is within the above range, a practical polishing rate can be obtained while reducing the corrosion of the surface to be processed having a tungsten film or the like.

1.2.2. Acidic compound The chemical mechanical polishing composition according to the present embodiment may contain an acidic compound. Examples of acidic compounds include organic acids and inorganic acids. Therefore, the chemical mechanical polishing composition according to the present embodiment can use at least one selected from organic acids and inorganic acids. The acidic compound has an effect of increasing the polishing rate of the silicon nitride film, in particular, due to a synergistic effect with (A) silica particles.

  The organic acid is not particularly limited, and examples thereof include malonic acid, maleic acid, citric acid, malic acid, tartaric acid, oxalic acid, lactic acid, and the like, and salts thereof. Of these, tartaric acid, malic acid and citric acid are more preferred, and tartaric acid is particularly preferred. The tartaric acid, malic acid and citric acid exemplified above have two or more carboxyl groups and one or more hydroxyl groups in the molecule. Since this hydroxyl group can form a hydrogen bond with a nitrogen atom existing in the silicon nitride film, a large amount of the organic acids exemplified above are present on the surface of the silicon nitride film. Thereby, the polishing rate of the silicon nitride film can be increased by the etching action of the carboxyl group in the organic acid exemplified above.

  As described above, by using the tartaric acid, malic acid, and citric acid exemplified above as the acidic compound, the polishing rate for the silicon nitride film can be further increased.

Although it does not restrict | limit especially as an inorganic acid, For example, these salts and derivatives, such as phosphoric acid, a sulfuric acid, hydrochloric acid, nitric acid, are mentioned. For example, when phosphoric acid or a derivative thereof is added, the polishing rate for the silicon nitride film can be increased. This is presumed to be achieved by the synergistic effect of the chemical polishing action of phosphoric acid on the silicon nitride film and the mechanical polishing action of colloidal silica. Thereby, the polishing rate for the silicon nitride film and the silicon oxide film can be adjusted.

1.2.3. Amine Compound The chemical mechanical polishing composition according to this embodiment preferably contains an amine compound. In this embodiment, the amine compound has a function as a so-called etching agent. By adding an amine compound in the chemical mechanical polishing composition according to the present embodiment, a metal oxide film (for example, CuO, Cu ₂ O and Cu (OH) ₂ layer) or an organic residue on the wiring substrate in the CMP process. (Eg BTA layer) can be removed by etching.

  Examples of amine compounds include alkanolamines, primary amines, secondary amines, and tertiary amines.

  As alkanolamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N, N-diethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N -Dibutylethanolamine, N- (β-aminoethyl) ethanolamine, N-ethylethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine and the like. Examples of the primary amine include methylamine, ethylamine, propylamine, butylamine, pentylamine, 1,3-propanediamine and the like. Secondary amines include piperidine, piperazine and the like. Examples of the tertiary amine include trimethylamine and triethylamine. These amine compounds may be used alone or in combination of two or more.

  Among these amine compounds, monoethanolamine and monoisopropanolamine are preferable because they have a high effect of etching a metal oxide film and an organic residue on a wiring board.

  The content ratio of the amine compound is preferably 0.0001% by mass or more and 1% by mass or less, more preferably 0.0005% by mass or more and 0.5% by mass or less, particularly with respect to the total mass of the chemical mechanical polishing composition. Preferably they are 0.001 mass% or more and 0.1 mass% or less. When the content ratio of the amine compound is within the above range, the metal oxide film or organic residue on the wiring board is removed while suppressing the corrosion of the surface to be cleaned and obtaining a good surface to be polished in the cleaning step after the CMP. It can be effectively removed by etching.

1.2.4. Water-soluble polymer The chemical mechanical polishing composition according to this embodiment preferably contains a water-soluble polymer. The water-soluble polymer is a water-soluble polymer having at least one functional group selected from the group consisting of a carboxyl group, a sulfo group, and an amino group. The water-soluble polymer has a function of reducing corrosion by adsorbing to the surface of the surface to be polished. Therefore, when a water-soluble polymer is added to the chemical mechanical polishing composition, the effect of reducing the corrosion of the surface to be polished is improved. However, the water-soluble polymer does not contain the polymer (A).

  In the present invention, “water-soluble” means that the mass dissolved in 100 g of water at 20 ° C. is 0.1 g or more.

  The water-soluble polymer is not particularly limited as long as it is a water-soluble polymer having at least one functional group selected from the group consisting of a carboxyl group, a sulfo group, and an amino group. Examples of the polymer used in the water-soluble polymer component include a copolymer containing acrylic acid, methacrylic acid, maleic acid, itaconic acid, styrene sulfonic acid, or a derivative thereof as a repeating unit. These repeating units can be used alone or in combination of two or more.

  The weight average molecular weight (Mw) of the water-soluble polymer is preferably from 2,000 to 1,500,000, more preferably from 3,000 to 1,200,000. In the present specification, “weight average molecular weight” refers to a weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

  The content of the water-soluble polymer is preferably adjusted so that the viscosity at room temperature is 2 mPa · s or less so that the chemical mechanical polishing composition can be stably supplied to the surface to be polished. Since the viscosity of the chemical mechanical polishing composition is almost determined by the average molecular weight and content of the water-soluble polymer, it may be adjusted in consideration of the balance between them.

  For example, the content of the water-soluble polymer is preferably 0.0001% by mass or more and 1% by mass or less, more preferably 0.0005% by mass or more and 0.5% by mass with respect to the total mass of the chemical mechanical polishing composition. % Or less, particularly preferably 0.001% by mass or more and 0.1% by mass or less. When the content ratio of the water-soluble polymer is in the previous range, it is possible to achieve both the suppression of corrosion and the effect of removing particles and metal impurities contained in the CMP slurry from the wiring board.

1.2.5. pH adjuster The chemical mechanical polishing composition according to this embodiment preferably has a pH of 1 or more, more preferably 2 or more and 14 or less, and even more preferably 2 or more and 11 or less.

  As described above, the cleaning composition according to this embodiment preferably has a pH of 1 or more. Examples of the pH adjuster include acidic compounds such as phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide and cesium hydroxide, tetramethylammonium hydroxide. It is preferable to use an organic ammonium salt such as ammonia or a basic compound such as ammonia. These pH adjusting agents may be used alone or in combination of two or more.

  Among these pH adjusters, organic ammonium salts used in general alkaline cleaners are feared for health damage to the human body, so sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide Alkali metal hydroxides are preferred, and potassium hydroxide is more preferred.

1.2.6. Surfactant A surfactant may be further added to the chemical mechanical polishing composition according to this embodiment, and among these, a nonionic surfactant is preferable. The surfactant has an effect of imparting an appropriate viscosity to the chemical mechanical polishing aqueous dispersion. The viscosity of the chemical mechanical polishing aqueous dispersion is preferably adjusted to be 0.5 mPa · s or more and less than 10 mPa · s at 25 ° C.

  Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, polyoxy Polyoxyethylene aryl ethers such as ethylene nonylphenyl ether; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxy And polyoxyethylene sorbitan fatty acid esters such as ethylene sorbitan monostearate. The nonionic surfactants exemplified above may be used singly or in combination of two or more.

  The content ratio of the nonionic surfactant is preferably 0.001% by mass or more and 1.0% by mass or less, more preferably 0.002% by mass or more and 0.5% by mass with respect to the total mass of the chemical mechanical polishing composition. It is not more than mass%, particularly preferably not less than 0.003 mass% and not more than 0.1 mass%.

1.2.7. Corrosion-proofing agent You may add a corrosion-proofing agent to the chemical mechanical polishing composition which concerns on this Embodiment further as needed. Examples of the corrosion inhibitor include benzotriazole and derivatives thereof. Here, the benzotriazole derivative means one obtained by substituting one or more hydrogen atoms of benzotriazole with, for example, a carboxyl group, a methyl group, an amino group, a hydroxyl group or the like. Examples of the benzotriazole derivative include 4-carboxylbenzotriazole and its salt, 7-carboxybenzotriazole and its salt, benzotriazole butyl ester, 1-hydroxymethylbenzotriazole, 1-hydroxybenzotriazole and the like.

1.2.8. Oxidizing agent The chemical mechanical polishing composition according to the present embodiment may further contain an oxidizing agent as necessary. Examples of the oxidizing agent include persulfates such as ammonium persulfate and potassium persulfate, hydrogen peroxide, the following various heteropolyacids and permanganate compounds such as potassium permanganate, and dichromic acids such as potassium dichromate. Examples thereof include polyvalent metal salts such as compounds.

  A heteropolyacid is a polyacid having two or more metals formed by condensation of an inorganic acid, and its central atom is Cu, Be, B, Al, C, Si, Ge, Sn, Ti, Zr, Ce , Th, N, P, As, Sb, V, Nb, Ta, Cr, Mo, W, U, S, Se, Te, Mn, I, Fe, Co, Ni, Rh, Os, Ir, Pt, etc. is there. The heteroatoms combined with these central atoms are Cu, Be, B, Al, C, Si, Ge, Sn, Ti, Zr, Ce, Th, N, P, As, Sb, V, Nb, Ta. , Cr, Mo, W, U, S, Se, Te, Mn, I, Fe, Co, Ni, Rh, Os, Ir, and Pt are atoms different from the central atom. As the heteropolyacid, those in which the central atom is V, Mo or W and the heteroatom is Si or P are preferable.

  Specific examples of the heteropolyacid include silicomolybdic acid, phosphomolybdic acid, silicotungstic acid, and phosphotungstic acid. Of these oxidizing agents, preferred are ammonium persulfate, potassium persulfate and hydrogen peroxide, with ammonium persulfate being particularly preferred.

  The content of the oxidizing agent can be 0.01 to 10% by mass when the aqueous dispersion is 100% by mass, particularly 0.05 to 5% by mass, and further 0.1 to 3% by mass. It is preferable to do. If the oxidizing agent is contained in an amount of 10% by mass, the polishing rate can be sufficiently improved, and it is not necessary to contain it in a large amount exceeding 10% by mass.

1.2.9. Aqueous medium The chemical mechanical polishing composition according to this embodiment preferably dissolves or disperses the above components in an aqueous medium, and the aqueous medium used may serve as a solvent mainly composed of water. There is no particular limitation as long as it is possible. Examples of such an aqueous medium include water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent having compatibility with water. Among these, water, a mixed medium of water and alcohol are preferably used, and water is more preferably used.

  Examples of such water include ultrapure water, pure water, ion exchange water, and distilled water. Ultrapure water, pure water, and ion exchange water are preferable, and ultrapure water is more preferable. Ultrapure water and pure water can be obtained by passing tap water through activated carbon, subjecting it to ion exchange treatment, and further distilling it, irradiating it with a predetermined ultraviolet germicidal lamp or passing through a filter as necessary.

1.3. Use The chemical mechanical polishing composition according to the present embodiment can be used as an abrasive for polishing a positively charged substrate during chemical mechanical polishing among a plurality of substrates mainly constituting a semiconductor device. . As a typical substrate that is positively charged during chemical mechanical polishing, a silicon material can be given. Examples of the silicon material include single silicon such as silicon single crystal, amorphous silicon, polysilicon, and doped polysilicon, and silicon nitride and silicon oxide. The chemical mechanical polishing composition according to the present embodiment is particularly suitable for a polishing composition mainly used in applications for polishing these silicon materials and a polishing method using the same.

1.4. Method for Preparing Chemical Mechanical Polishing Composition The method for preparing the chemical mechanical polishing composition according to this embodiment is not particularly limited. For example, by adding the above-described components to an aqueous medium and stirring and mixing the components. There is a method in which each component is dissolved in an aqueous medium, and then a pH adjusting agent is added to adjust to a predetermined pH. There is no particular limitation on the mixing order and mixing method of each component other than the pH adjuster, and any method may be applied as long as it can be uniformly dissolved or dispersed.

  Moreover, the chemical mechanical polishing composition according to this embodiment can be prepared as a concentrated stock solution and diluted with an aqueous medium when used.

2. Chemical mechanical polishing method The chemical mechanical polishing method according to the present embodiment uses the chemical mechanical polishing composition according to the present invention described above, and among the plurality of substrates constituting the semiconductor device, a positive charge is obtained during chemical mechanical polishing. It is characterized by polishing a substrate (for example, a silicon nitride film) bearing the above. Hereinafter, a specific example of the chemical mechanical polishing method according to the present embodiment will be described in detail with reference to the drawings.

2.1. FIG. 1 is a cross-sectional view schematically showing a target object suitable for use in the chemical mechanical polishing method according to the present embodiment. The target object 100 is formed through the following steps (1) to (4).

  (1) First, the silicon substrate 10 is prepared. A functional device such as a transistor (not shown) may be formed on the silicon substrate 10.

  (2) Next, a first silicon oxide film 12 is formed on the silicon substrate 10 using a CVD method or a thermal oxidation method. Further, a silicon nitride film 14 is formed on the first silicon oxide film 12 by using the CVD method.

  (3) Next, the silicon nitride film 14 is patterned. Using this as a mask, the trench 20 is formed by applying a lithography method or an etching method.

  (4) Next, when the second silicon oxide film 16 is deposited by the high-density plasma CVD method so as to fill the trench 20, the object 100 is obtained.

2.2. Chemical mechanical polishing method 2.2.1. First Polishing Step First, in order to remove the second silicon oxide film 16 deposited on the silicon nitride film 14 of the workpiece 100 as shown in FIG. 1, a chemical mechanical polishing composition having a high silicon oxide film selection ratio. A 1st grinding | polishing process is performed using a thing. FIG. 2 is a cross-sectional view schematically showing the object to be processed at the end of the first polishing process. In the first polishing step, the silicon nitride film 14 serves as a stopper, and polishing can be stopped on the surface of the silicon nitride film 14. At this time, dishing occurs in the trench 20 filled with silicon oxide. As a result, as shown in FIG. 2, the silicon nitride film 14 remains, but a polishing residue of the second silicon oxide film 16 often remains on the silicon nitride film 14. This polishing residue may affect the subsequent polishing of the silicon nitride film 14.

2.2.2. Second polishing process
Next, in order to remove the silicon nitride film 14 shown in FIG. 2, a second polishing process is performed using the chemical mechanical polishing composition according to the present embodiment described above. FIG. 3 is a cross-sectional view schematically showing the object to be processed at the end of the second polishing step. The chemical mechanical polishing composition according to the present embodiment has a sufficiently high polishing rate ratio of the silicon nitride film to the silicon oxide film, and the polishing rate of the silicon oxide film is not extremely low. The silicon nitride film 14 can be smoothly polished and removed without being affected by the above. In this way, a semiconductor device in which silicon oxide is embedded in the trench 20 as shown in FIG. 3 can be obtained. The chemical mechanical polishing method according to the present embodiment can be applied to, for example, trench isolation (STI).

2.3. Chemical Mechanical Polishing Device For example, a chemical mechanical polishing device 200 as shown in FIG. 4 can be used in the first polishing step and the second polishing step described above. FIG. 4 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. In each polishing step, a carrier (a chemical mechanical polishing composition) 44 is supplied from a slurry supply nozzle 42 and a carrier head 52 holding a semiconductor substrate 50 while rotating a turntable 48 to which a polishing cloth 46 is attached. This is done by bringing them into contact. In FIG. 4, the water supply nozzle 54 and the dresser 56 are also shown.

  The pressing pressure of the carrier head 52 can be selected within a range of 10 to 1,000 hPa, and preferably 30 to 500 hPa. Moreover, the rotation speed of the turntable 48 and the carrier head 52 can be suitably selected within the range of 10 to 400 rpm, and preferably 30 to 150 rpm. The flow rate of the slurry (chemical mechanical polishing composition) 44 supplied from the slurry supply nozzle 42 can be selected within the range of 10 to 1,000 mL / min, and preferably 50 to 400 mL / min.

  As a commercially available polishing apparatus, for example, “EPO-112”, “EPO-222” manufactured by Ebara Manufacturing Co., Ltd .; “LGP-510”, “LGP-552” manufactured by Lappmaster SFT, manufactured by Applied Materials , “Mirra”, “Reflexion” and the like.

3. Examples Hereinafter, the present invention will be described by way of examples. However, the present invention is not limited to these examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Each analysis condition in the examples is as follows.
<Molecular weight measurement>
The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the polymer were measured by gel permeation chromatography under the following conditions.
Column: “TSKgel αM” and “TSKgel α2500” from Tosoh Corporation are connected in series. All column sizes are 7.8 x 300 mm.
Solvent: N-methyl-2-pyrrolidone added with lithium bromide (30 mmol / L in terms of lithium bromide monohydrate) and phosphoric acid (10 mmol / L) Flow rate: 1 ml / min
・ Temperature: 40 ℃
・ Detection method: Refractive index method ・ Standard material: Polystyrene ・ GPC apparatus: manufactured by Tosoh Corporation, apparatus name “HLC-8020-GPC”
<NMR spectrum>
The content of the structural unit contained in the polymer was measured by ¹ H-NMR and ¹³ C-NMR analysis. Using a nuclear magnetic resonance apparatus “ECP400” (manufactured by JEOL Ltd.), a heavy solvent having the highest polymer solubility was selected from deuterated chloroform, deuterated methanol and deuterated water.

3.1. Synthesis of Polymer (A3) Polymer (A3) was synthesized based on the following scheme.

3.1.1. Synthesis of Polymer (A1) In a 500 ml flask equipped with a stirrer, polybutadiene (Cis-1,4 bond content = 20 mol%, Trans-1,4 bond content = 55 mol%, 1,2 bond content = 25 mol%) 23.6 g, formic acid 5.9 g and toluene 240 ml were added. The mixture was heated to 60 ° C., and 55.9 g of 31 mass% hydrogen peroxide was added over 15 minutes while stirring. The reaction was allowed to proceed for 150 minutes, followed by cooling to 23 ° C. This reaction solution was washed with an aqueous sodium hydrogen carbonate solution and water, and the solvent was distilled off to obtain a polymer (A1). ^{From 1} H-NMR, the polymer (A1) is a polymer in which a part of unsaturated groups of polybutadiene is epoxidized, and the epoxidation rate [(number of epoxidized unsaturated groups / polybutadiene before epoxidation) Number of unsaturated groups contained) × 100 (%)] was 60%. Moreover, Mn was 5400, Mw was 9500, and Mw / Mn was 1.76.

3.1.2. Synthesis of polymer (A2) In a 100 ml flask, 5.2 g of the above polymer (A1), 4.4 g of α-thioglycerol, 0.85 g of lithium hydroxide monohydrate, 6.6 ml of methanol (MeOH), tetrahydrofuran (THF) (5.8 ml) was added, and the mixture was heated with stirring at 60 ° C. for 2 hours. Then, it cooled to 23 degreeC and reprecipitated with water. The precipitate was vacuum dried at 60 ° C. to obtain a polymer (A2). ^{From 1} H-NMR, it was found that the polymer (A2) had a thioether structure.

3.1.3. Synthesis of polymer (A3) To the 100 ml flask, 5.0 g of the above polymer (A2), 4.6 g of 31% by mass hydrogen peroxide, and 25.3 ml of methanol (MeOH) were added and heated at 40 ° C. for 2 hours. Stir. Then, it cooled to 23 degreeC and reprecipitated with isopropanol. The precipitate was vacuum dried at 60 ° C. to obtain a white solid polymer (A3). ^{From 1} H-NMR, it was found that the polymer (A3) had a sulfinyl group.

3.2. Synthesis of Polymer (A6) Polymer (A6) was synthesized based on the following scheme.

3.2.1. Synthesis of Polymer (A4) 6.79 g of glycidyl methacrylate and 2.27 g of styrene, 0.272 g of 2,2′-azobis (isobutyronitrile) as a polymerization initiator, 18.9 g of N, N-dimethylformamide Were mixed and placed in a flask. Nitrogen was blown into this, the temperature was raised to 70 ° C., polymerized for 6 hours, and then cooled to room temperature. This solution was purified by reprecipitation with methanol and dried under reduced pressure to obtain a polymer (A4). In the obtained polymer (A4), the content of repeating units derived from glycidyl methacrylate was 67 mol%, and the content of repeating units derived from styrene was 33 mol%.

3.2.2. Synthesis of Polymer (A5) 1 g of the above polymer (A4) and 4.47 g of thioglycerol and 9.45 g of N, N-dimethylformamide were mixed and placed in a flask. The temperature was raised to 60 ° C. while blowing nitrogen, and 16.7 g of triethylamine was added as a catalyst, followed by reaction for 4 hours, and then cooled to room temperature. This solution was purified by reprecipitation with water and freeze-dried to obtain a polymer (A5).

3.2.3. Synthesis of Polymer (A6) 0.1 g of the above-mentioned polymer (A5) was dispersed in 0.844 g of water and put into a flask. To this, 0.056 g of 30% aqueous hydrogen peroxide solution was added and reacted at room temperature for 18 hours. The aqueous solution obtained was dialyzed to obtain a copolymer (A6) (yield: 27%). When the polymer (A6) and water were mixed and the concentration was adjusted to 1% by mass, the copolymer (A6) was dissolved in water. Moreover, the weight average molecular weight of the obtained copolymer (A6) was 50000, and molecular weight distribution was 2.17. The structure of the polymer (A6) was confirmed by ¹³ C-NMR.

3.3. Synthesis of Polymer (A7) 100 g of a random copolymer of styrene / isoprene (20/80 molar ratio) was charged into a container having an internal volume of 3 liters and dissolved in 1 liter of dioxane. After dissolution, anhydrous sulfuric acid / dioxane complex (85 g / 500 g) was dropped into the container while maintaining the internal temperature at 25 ° C., and then stirred at 25 ° C. for 1 hour. Thereafter, the solvent was removed to obtain a sulfonated product (A7) of a styrene / isoprene (20/80 molar ratio) random copolymer. The weight average molecular weight of the polymer was 5,000.

3.4. Preparation of Chemical Mechanical Polishing Composition Each component was added to a polyethylene container so as to have the concentration shown in Table 1 as a chemical mechanical polishing composition, and an appropriate amount of ion-exchanged water was added and stirred for 15 minutes. To this mixture, ion-exchanged water is added so that the total amount of all the constituent components becomes 100 parts by mass, and the pH is adjusted to the pH shown in Table 1 using a pH adjuster. Thus, each chemical mechanical polishing composition shown in Table 1 was obtained. The pH was measured using a pH meter “F52” manufactured by Horiba, Ltd.

3.5. Chemical Mechanical Polishing Test Using the chemical mechanical polishing composition prepared in “3.4. Preparation of Chemical Mechanical Polishing Composition”, a silicon substrate with a silicon nitride film, silicon oxide film or polysilicon film having a diameter of 8 inches was used. As the object to be polished, chemical mechanical polishing was performed on each film under the following polishing condition 1.
<Polishing condition 1>
・ Polisher: G & P TECHNOLOGY, “POLI-400L”
・ Polishing pad: Rodel Nitta Co., Ltd. “IC1000”
・ Chemical mechanical polishing aqueous dispersion supply speed: 100 mL / min ・ Surface plate rotation speed: 100 rpm
・ Rotation speed of polishing head: 90 rpm
Polishing head pressing pressure: 2 psihPa
3.5.1. Calculation of polishing rate The film thickness before polishing for each of the 4 × 4 cm cut wafer polysilicon film (Poly-Si) or amorphous silicon (A-Si) substrate to be polished is a light made by Filmetrics Co., Ltd. It measured beforehand using the interference type film thickness meter "F20 film thickness measurement system", and it grind | polished for 1 minute on said conditions. The film thickness of the polished object after polishing was similarly measured using an optical interference film thickness meter, and the difference between the film thickness before and after polishing, that is, the film thickness decreased by chemical mechanical polishing was determined. Then, the polishing rate was calculated from the film thickness decreased by chemical mechanical polishing and the polishing time. The results are also shown in Table 1.

3.6. Evaluation Results Table 1 shows the composition and evaluation results of the chemical mechanical polishing composition.

The following components in Table 1 will be supplemented.
・ Jurimer AC-10H (manufactured by Toa Gosei Co., Ltd., polyacrylic acid, Mw = 700,000)
・ Alastar 703S (Arakawa Chemical Co., Ltd., styrene maleic acid resin)
・ PL-3 (manufactured by Fuso Chemical Industries, colloidal silica aqueous dispersion)
As apparent from Table 1 above, when the chemical mechanical polishing composition according to Examples 1 to 7 was used, a high polishing rate could be obtained for any silicon material.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

10 · 110: silicon substrate (bare silicon), 12 · 112 ... first silicon oxide film, 1
4 · 114: silicon nitride film, 16 · 116: second silicon oxide film, 20 ... trench, 4
2 ... Slurry supply nozzle, 44 ... Slurry, 46 ... Polishing cloth, 48 ... Turntable, 50
... Semiconductor substrate, 52 ... Carrier head, 54 ... Water supply nozzle, 56 ... Dresser, 10
0.300 ... object to be processed, 200 ... chemical mechanical polishing equipment

Claims (7)

  A chemical mechanical polishing composition comprising a compound containing a sulfinyl group.   The chemical mechanical polishing composition according to claim 1, wherein the compound contains a polymer (A) having a repeating unit having a sulfinyl group in the side chain. The chemical mechanical polishing composition according to claim 2, wherein the repeating unit having the sulfinyl group in the side chain is represented by the following general formula (1).
(1)
(In General Formula (1), R ³ represents a direct bond or a divalent organic group having 1 to 24 carbon atoms, and R ⁴ represents an alkyl group having 1 to 20 carbon atoms which may have a substituent or a substituted group. An aryl group having 6 to 20 carbon atoms which may have a group is shown.) The chemical mechanical polishing composition according to claim 3, wherein the repeating unit having the sulfinyl group in the side chain is represented by the following general formula (2).
(2)
(In General Formula (2), each R ¹ independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and R ² represents a direct bond, —O—, * — (C═O) —O—, * ^{- (C = O) -NR 6} -, * - NR 6 - (C = O) - (R 6 is a hydrogen atom or an organic group having 1 to 10 carbon atoms, * the general formula (2) R ¹ represents a position bonded to the carbon atom to which R ¹ is bonded) or a phenylene group, R ⁵ represents a hydrogen atom or —OR ⁷ (R ⁷ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms) R ⁸ represents each independently a direct bond or a C1-C10 alkanediyl group which may have a substituent, and R ³ and R ⁴ are as defined above.   The polymer (A) further has a repeating unit derived from one or more monomers selected from conjugated dienes, styrenes, (meth) acrylates and (meth) acrylamides. The chemical mechanical polishing composition according to claim 4.   The chemical mechanical polishing composition according to claim 1 or 5, wherein the polishing surface contains a silicon material. A polishing purification method comprising a step of polishing a wiring substrate containing a silicon material using the chemical mechanical polishing composition according to any one of claims 1 to 6.