WO2023085008A1

WO2023085008A1 - Chemical-mechanical polishing composition, production method therefor, and polishing method

Info

Publication number: WO2023085008A1
Application number: PCT/JP2022/038748
Authority: WO
Inventors: 昂輝石牧; 弥里山口
Original assignee: Jsr株式会社
Priority date: 2021-11-12
Filing date: 2022-10-18
Publication date: 2023-05-19
Also published as: TW202320159A

Abstract

The present invention provides a chemical-mechanical polishing composition with which it is possible to polish a molybdenum film and a silicon dioxide film at a stable polishing rate, and suppress corrosion of the molybdenum film.　A chemical-mechanical polishing composition according to the present invention contains abrasive grains (A) and an iron(III) compound (B), wherein the iron(III) compound (B) is a chelate compound.

Description

Chemical mechanical polishing composition, production method thereof, and polishing method

The present invention relates to a chemical mechanical polishing composition, a method for producing the same, and a polishing method using the same.

With the improvement of semiconductor integrated circuit manufacturing technology, there is a demand for high integration and high-speed operation of semiconductor elements. Along with this, the flatness of the semiconductor substrate surface required in the manufacturing process of fine circuits in semiconductor devices is becoming more stringent, and chemical mechanical polishing (CMP) is an indispensable technology in the manufacturing process of semiconductor devices. It has become.

　Tungsten, which has excellent embedding properties, is often used in via holes that electrically connect wiring in the vertical direction of semiconductor substrates manufactured through CMP. As a chemical mechanical polishing composition used for polishing a tungsten film, a polishing composition containing an oxidizing agent such as hydrogen peroxide, an iron catalyst such as iron nitrate, and abrasive grains such as silica has been proposed. (See, for example, Patent Document 1). Furthermore, in recent years, molybdenum has been used in place of tungsten because of its lower hardness and easier processing than tungsten, and chemical mechanical polishing compositions used for polishing molybdenum films have been investigated (for example, , see Patent Document 2).

Japanese Patent Publication No. 2008-503875 International Publication No. 2013/188296

In CMP for forming via holes using molybdenum, it is necessary to polish and planarize the embedded molybdenum film and the surrounding silicon oxide film in the same process. In order to achieve this, there is a need for a chemical mechanical polishing composition capable of polishing molybdenum films and silicon oxide films at a stable polishing rate. In addition, since molybdenum has a lower hardness than tungsten, there is a problem that corrosion is more likely to occur in CMP.

Some aspects of the present invention provide a chemical mechanical polishing composition capable of polishing a molybdenum film and a silicon oxide film at a stable polishing rate and suppressing corrosion of the molybdenum film. be.

The present invention has been made to solve at least part of the above-mentioned problems, and can be implemented as any of the following aspects.

One aspect of the chemical mechanical polishing composition according to the present invention is
containing abrasive grains (A) and an iron (III) compound (B),
The iron (III) compound (B) is a chelate compound.

In one aspect of the chemical mechanical polishing composition,
A compound (C ) may be further contained.

In any aspect of the chemical mechanical polishing composition,
The average secondary particle size of the abrasive grains (A) in the chemical mechanical polishing composition may be 5 nm or more and 100 nm or less.

In any aspect of the chemical mechanical polishing composition,
The association degree of the abrasive grains (A) in the chemical mechanical polishing composition may be 1.0 or more and 2.0 or less.

In any aspect of the chemical mechanical polishing composition,
The zeta potential of the abrasive grains (A) in the chemical mechanical polishing composition may be less than 0 mV.

In any aspect of the chemical mechanical polishing composition,
The abrasive grain (A) may have at least one functional group among the functional group represented by the following general formula (1) and the functional group represented by the following general formula (2).
- SO ₃ ^- M ⁺ (1)
- COO ^- M ⁺ (2)
(In formulas (1) and (2) above, M ⁺ represents a monovalent cation.)

In any aspect of the chemical mechanical polishing composition,
The pH may be 1 or more and 6 or less.

One aspect of the polishing method according to the present invention is
A step of polishing a semiconductor substrate using the chemical mechanical polishing composition according to any one of the above aspects.

In one aspect of the polishing method,
The semiconductor substrate may have a portion composed of at least one selected from the group consisting of molybdenum and molybdenum alloys.

One aspect of the chemical mechanical polishing composition according to the present invention is
Dissolving or dispersing abrasive grains (A) and iron (III) compound (B) in a liquid medium,
The iron (III) compound (B) is a chelate compound.

By using the chemical mechanical polishing composition according to the present invention, it is possible to polish a semiconductor substrate including a molybdenum film and a silicon oxide film at a stable polishing rate while suppressing corrosion of the molybdenum film.

FIG. 1 is a cross-sectional view schematically showing an object to be processed suitable for use in the polishing process according to this embodiment. FIG. 2 is a cross-sectional view schematically showing the object to be processed at the end of the first polishing step. FIG. 3 is a cross-sectional view schematically showing the object to be processed at the end of the second polishing step. FIG. 4 is a perspective view schematically showing a chemical mechanical polishing apparatus.

A preferred embodiment of the present invention will be described in detail below. In addition, the present invention is not limited to the following embodiments, and includes various modifications implemented without changing the gist of the present invention.

In this specification, the numerical range described as "X to Y" is interpreted as including the numerical value X as the lower limit and the numerical value Y as the upper limit.

1. Chemical mechanical polishing composition The chemical mechanical polishing composition according to one embodiment of the present invention comprises abrasive grains (A) (also referred to herein as “component (A)”) and an iron (III) compound ( B) (herein also referred to as “component (B)”), wherein the iron (III) compound (B) is a chelate compound.

Each component contained in the chemical mechanical polishing composition according to the present embodiment will be described in detail below.

1.1. Component (A)
The chemical mechanical polishing composition according to this embodiment contains abrasive grains (A). Component (A) may be either inorganic or organic particles, but inorganic particles are preferred. Examples of inorganic particles include inorganic oxide particles such as silica, ceria, alumina, zirconia, and titania. Among these, silica particles are preferred. Examples of silica particles include fumed silica and colloidal silica, with colloidal silica being preferred.

The shape of component (A) is not particularly limited, and may be spherical, cocoon-shaped, chain-spherical, or have a plurality of projections on the surface. Abrasive grains having a plurality of projections on their surfaces can be produced by applying the methods described in, for example, Japanese Patent Application Laid-Open No. 2007-153732 and Japanese Patent Application Laid-Open No. 2013-121631.

The zeta potential of component (A) in the chemical mechanical polishing composition is preferably less than 0 mV, which is a negative zeta potential, more preferably -10 mV or less, and particularly preferably -15 mV or less. When the zeta potential of the component (A) is within the above range, the electrostatic repulsive force between the abrasive grains can effectively prevent the particles from aggregating with each other, thereby improving the storage stability of the chemical mechanical polishing composition. At the same time, a semiconductor substrate including a molybdenum film and a silicon oxide film can be polished at a more stable polishing rate. In addition, as the zeta potential measuring device, "ELSZ-2000ZS" manufactured by Otsuka Electronics Co., Ltd., "Zetasizer Ultra" manufactured by Malvern, Dispersion Technology Inc. and "DT300" manufactured by K.K.

At least part of the surface of component (A) is a functional group represented by the following general formula (1) and a functional group represented by the following general formula (2) (hereinafter also referred to as "specific functional group"). At least one of them may have a functional group.
- SO ₃ ^- M ⁺ (1)
- COO ^- M ⁺ (2)
(In formulas (1) and (2) above, M ⁺ represents a monovalent cation.)

Abrasive grains having at least a portion of the surface modified with specific functional groups have a larger absolute value of zeta potential than abrasive grains not surface-modified with specific functional groups, and the electrostatic repulsion between abrasive grains increases. do. As a result, the dispersibility of abrasive grains in the chemical mechanical polishing composition is improved, so that semiconductor substrates containing molybdenum films and silicon oxide films can be polished at a more stable polishing rate while reducing the occurrence of polishing scratches and dishing. sometimes you can.

Examples of monovalent cations represented by M ⁺ in general formula (1) include, but are not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . That is, the functional group represented by the general formula (1) can be rephrased as "at least one functional group selected from the group consisting of a sulfo group and a salt thereof". Here, the "salt of a sulfo group" means that the hydrogen ion contained in the sulfo group (--SO ₃ H) is replaced with a monovalent cation such as Li ⁺ , Na ⁺ , K ⁺ , NH ₄ ⁺ Refers to functional groups. Component (A) having a functional group represented by the general formula (1) is an abrasive grain having a functional group represented by the general formula (1) fixed to its surface via a covalent bond. Abrasive grains to which a compound having a functional group represented by the general formula (1) is physically or ionically adsorbed on the surface are not included.

The component (A) having the functional group represented by the above general formula (1) can be produced as follows. First, silica prepared by a known method and a mercapto group-containing silane coupling agent are sufficiently stirred in an acidic medium to covalently bond the mercapto group-containing silane coupling agent to the surface of the silica. Examples of mercapto group-containing silane coupling agents include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. Next, by further adding an appropriate amount of hydrogen peroxide and allowing to stand sufficiently, the component (A) having the functional group represented by the general formula (1) can be obtained.

The component (A) having a functional group represented by the general formula (1) has a negative zeta potential in the chemical mechanical polishing composition, and the negative potential is preferably less than 0 mV, more preferably. is -10 mV or less, particularly preferably -15 mV or less. When the zeta potential of the component (A) is within the above range, the electrostatic repulsive force between the abrasive grains effectively prevents the particles from aggregating, and the semiconductor substrate including the molybdenum film and the silicon oxide film can be polished at a more stable polishing rate. can be polished with In addition, the apparatus mentioned above can be used for a zeta-potential measuring apparatus. The zeta potential of component (A) having a functional group represented by general formula (1) can be adjusted by appropriately increasing or decreasing the amount of the mercapto group-containing silane coupling agent or the like added.

Examples of monovalent cations represented by M ⁺ in general formula (2) include, but are not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . That is, the functional group represented by the above general formula (2) can also be rephrased as "at least one functional group selected from the group consisting of a carboxy group and a salt thereof". Here, the term "salt of carboxy group" refers to a functional group obtained by substituting a monovalent cation such as Li ⁺ , Na ⁺ , K ⁺ , NH ₄ ⁺ for the hydrogen ion contained in the carboxy group (-COOH). That's what I mean. The component (A) having the functional group represented by the general formula (2) is an abrasive grain having the functional group represented by the general formula (2) fixed to its surface via a covalent bond. Abrasive grains to which a compound having a functional group represented by the general formula (2) is physically or ionically adsorbed on the surface are not included.

The component (A) having the functional group represented by the general formula (2) can be produced as follows. First, silica prepared by a known method and a carboxylic anhydride-containing silane coupling agent are sufficiently stirred in a basic medium to covalently bond the carboxylic anhydride-containing silane coupling agent to the surface of the abrasive grains. Abrasive grains having a functional group represented by the above general formula (2) can be obtained by allowing the Examples of the carboxylic anhydride-containing silane coupling agent include 3-(triethoxysilyl)propylsuccinic anhydride.

The component (A) having a functional group represented by the general formula (2) has a negative zeta potential in the chemical mechanical polishing composition, and the negative potential is preferably less than 0 mV, more preferably. is -10 mV or less, particularly preferably -15 mV or less. When the zeta potential of the component (A) is within the above range, the electrostatic repulsive force between the abrasive grains effectively prevents the particles from aggregating, and the semiconductor substrate including the molybdenum film and the silicon oxide film can be polished at a more stable polishing rate. can be polished with In addition, the apparatus mentioned above can be used for a zeta-potential measuring apparatus. The zeta potential of the component (A) having the functional group represented by the general formula (2) can be adjusted by appropriately increasing or decreasing the amount of the above-described carboxylic anhydride-containing silane coupling agent or the like added.

The average secondary particle size of component (A) in the chemical mechanical polishing composition is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 10 nm or more. The average secondary particle size of component (A) in the chemical mechanical polishing composition is preferably 100 nm or less, more preferably 70 nm or less, and particularly preferably 60 nm or less. When the average secondary particle size of the component (A) is within the above range, the small particle size reduces the mechanical polishing performance, but the surface free energy increases, thereby improving the reactivity with molybdenum and silicon oxide. Therefore, it is possible to polish a semiconductor substrate containing a molybdenum film and a silicon oxide film at a more stable polishing rate, and obtain a highly stable chemical mechanical polishing composition that does not cause sedimentation and separation of particles. The average secondary particle size of the component (A) in the chemical mechanical polishing composition is the volume-based average particle size measured with a particle size distribution analyzer using a dynamic light scattering method. Examples of such a particle size distribution analyzer include model "Zetasizer Ultra" manufactured by Malvern.

The average primary particle size of component (A) in the chemical mechanical polishing composition is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 10 nm or more. The average primary particle size of component (A) in the chemical mechanical polishing composition is preferably 100 nm or less, more preferably 70 nm or less, and particularly preferably 60 nm or less. The average primary particle size of component (A) in the chemical mechanical polishing composition can be calculated by obtaining the average value of 50 particle sizes of component (A) by transmission electron microscope observation.

From the average secondary particle size and average primary particle size measured as described above, the degree of association, which is an indicator of the degree of aggregation of component (A) in the chemical mechanical polishing composition, is calculated using the following formula. can be calculated.
Degree of association = (average secondary particle size (nm)) / (average primary particle size (nm))

The association degree of component (A) in the chemical mechanical polishing composition is preferably 1.0 or more, more preferably 1.01 or more. The association degree of component (A) in the chemical mechanical polishing composition is preferably 2.0 or less, more preferably 1.7 or less, and particularly preferably 1.6 or less. When the degree of association of the component (A) is within the above range, the aggregation of the component (A) is suppressed and dispersed in the chemical mechanical polishing composition, and the surface free energy of the particles increases to molybdenum or silicon oxide. Since the reactivity with is improved, it may be possible to polish a semiconductor substrate including a molybdenum film and a silicon oxide film at a more stable polishing rate.

The content of component (A) in the chemical mechanical polishing composition according to the present embodiment is preferably 0.1% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. , more preferably 0.3% by mass or more, and particularly preferably 0.5% by mass or more. The content of component (A) in the chemical mechanical polishing composition according to the present embodiment is preferably 10% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. It is preferably 8% by mass or less, and particularly preferably 6% by mass or less. When the content of component (A) is within the above range, a semiconductor substrate containing a molybdenum film and a silicon oxide film can be polished at a stable polishing rate, and the storage stability of the chemical mechanical polishing composition may be improved. be.

1.2. Component (B)
The chemical mechanical polishing composition according to this embodiment contains an iron (III) compound (B). In the present invention, the iron (III) compound (B) is a chelate compound, specifically a chelate compound of iron (III) ions. Component (B) has the action of oxidizing the surface of the molybdenum film to create a fragile modified layer and promoting polishing of the molybdenum film.

A chelate compound of iron (III) ions can be created by reacting iron (III) ions with a chelating agent. When preparing the chemical mechanical polishing composition according to the present embodiment, it is necessary to add a chelate compound of iron (III) ions as component (B). By using a chelate compound of iron (III) ions as a raw material, iron (III) ions and the chelating agent can be present in the composition in substantially chemical equivalents, so that stable polishing properties can be exhibited. can be done. Alternatively, the iron (III) ion and chelating agent can be added separately and allowed to react in the composition to form an iron (III) ion chelate compound in situ, in which case Even if iron (III) ions and chelating agents are added in approximately equal amounts, they cannot be weighed with stoichiometric precision. As a result, excessive iron (III) ions or excessive chelating agents are liberated in the composition, compared to the case where a chelate compound of iron (III) ions is used as a raw material. Since iron (III) ions are a strong oxidizing agent, even if iron (III) ions are slightly excessively contained in the composition, molybdenum is excessively oxidized and corroded, resulting in stable development of polishing properties. becomes difficult. On the other hand, the chelating agent has a high coordinating ability to metals, and even if the composition contains a slight excess of the chelating agent, it excessively coordinates to the molybdenum surface and suppresses oxidation, which greatly increases the polishing rate. It becomes difficult to exhibit stable polishing characteristics such as lowering to

The chelating agent is not particularly limited as long as it is a compound capable of coordinating to iron (III) ion as a bidentate or higher ligand. Chelating agents such as acids, (polyhydric) oxycarboxylic acids, (polyhydric) phosphonic acids, and salts thereof can be used. Preferred examples of chelating agents include glycine, citric acid, tartaric acid, acetylacetone, dihydroxyethylglycine, glycoletherdiaminetetraacetic acid, dicarboxymethylglutamic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid. , 1,3-propanediaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, hydroxyethyliminodiacetic acid; pyrophosphoric acid, 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilotris (methylenephosphonic acid), 2-phosphonobutane-1,2,4-tricarboxylic acid, ethylenediaminetetra(methylenephosphonic acid); and salts thereof. Among these, ethylenediaminetetraacetic acid is particularly preferred. These chelating agents may be used alone or in combination of two or more.

For example, the chemical mechanical polishing composition for polishing tungsten described in JP-T-2008-503875 uses an iron (III) compound, specifically iron (III) nitrate. It is However, iron (III) nitrate cannot be used in the chemical mechanical polishing composition according to this embodiment. This is because when iron (III) nitrate is used, the action of nitrate ions excessively oxidizes the surface of the molybdenum film, and corrosion of the molybdenum film is likely to occur. Therefore, it is preferable that the chemical mechanical polishing composition according to the present embodiment contain as little nitrate ions as possible. The nitrate ion concentration in the chemical mechanical polishing composition according to this embodiment is preferably 200 ppm or less, more preferably 190 ppm or less, and particularly preferably 180 ppm or less. Even when the chemical mechanical polishing composition according to the present embodiment contains nitrate ions, a concentration of 0.005 ppm or more is permissible, and a concentration of 0.01 ppm or more is practically permissible. can do.

The content of component (B) in the chemical mechanical polishing composition according to the present embodiment is preferably 0.001% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. , more preferably 0.05% by mass or more, and particularly preferably 0.01% by mass or more. The content of component (B) in the chemical mechanical polishing composition according to the present embodiment is preferably 10% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. It is preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less. When the content of component (B) is within the above range, the molybdenum film can be oxidized to facilitate polishing, and excessive reaction between molybdenum and anionic species can be prevented, thereby reducing corrosion of the molybdenum film. Sometimes.

The concentration of iron (III) ions in the chemical mechanical polishing composition according to this embodiment is preferably 1 ppm or more, more preferably 3 ppm or more, and particularly preferably 5 ppm or more. The concentration of iron (III) ions in the chemical mechanical polishing composition according to this embodiment is preferably 1000 ppm or less, more preferably 900 ppm or less, and particularly preferably 800 ppm or less. When the concentration of iron (III) ions in the chemical mechanical polishing composition according to the present embodiment is within the above range, the molybdenum film can be oxidized to promote polishing, and excessive molybdenum and anionic species It may be possible to prevent the reaction and reduce the occurrence of corrosion of the molybdenum film.

1.3. Component (C)
The chemical mechanical polishing composition according to the present embodiment has at least one functional group selected from the group consisting of amino groups and salts thereof, and is selected from the group consisting of carboxy groups, sulfo groups, and salts thereof. It may contain a compound (C) having at least one functional group (also referred to herein as "component (C)"). Component (C) has the effect of reducing corrosion of the molybdenum film by adsorbing on the surface of the molybdenum film to form a protective film.

Amino groups and salts thereof include functional groups represented by the following general formula (3) or (4).
-NR ¹ R ² (3)
−N ⁺ R ¹ R ² X ⁽ 4)
(In the above formulas (3) and (4), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group. ^{X -} represents an anion.)

In general formulas (3) and (4) above, R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, and R ¹ and R ² are bonded may form a ring structure.

The hydrocarbon groups represented by R ¹ and R ² may be aliphatic hydrocarbon groups, aromatic hydrocarbon groups, araliphatic hydrocarbon groups or alicyclic hydrocarbon groups. Moreover, the aliphatic of the aliphatic hydrocarbon group and the araliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. These hydrocarbon groups include, for example, linear, branched or cyclic alkyl groups, alkenyl groups, aralkyl groups, and aryl groups.

The alkyl group is preferably a lower alkyl group having 1 to 6 carbon atoms, more preferably a lower alkyl group having 1 to 4 carbon atoms. Examples of such alkyl groups include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, sec-butyl group, tert-butyl group and n-pentyl group. , iso-pentyl group, sec-pentyl group, tert-pentyl group, neopentyl group, n-hexyl group, iso-hexyl group, sec-hexyl group, tert-hexyl group, cyclopentyl group, cyclohexyl group and the like.

The alkenyl group is preferably a lower alkenyl group having 1 to 6 carbon atoms, more preferably a lower alkenyl group having 1 to 4 carbon atoms. Examples of such alkenyl groups include vinyl groups, n-propenyl groups, iso-propenyl groups, n-butenyl groups, iso-butenyl groups, sec-butenyl groups, tert-butenyl groups and the like.

The aralkyl group preferably has 7 to 12 carbon atoms. Examples of such aralkyl groups include benzyl, phenethyl, phenylpropyl, phenylbutyl, phenylhexyl, methylbenzyl, methylphenethyl and ethylbenzyl groups.

The aryl group preferably has 6 to 14 carbon atoms. Examples of such aryl groups include phenyl, o-tolyl, m-tolyl, p-tolyl, 2,3-xylyl, 2,4-xylyl, 2,5-xylyl, 2 ,6-xylyl group, 3,5-xylyl group, naphthyl group, anthryl group and the like.

The aromatic ring of the aryl group and the aralkyl group may have, for example, a lower alkyl group such as a methyl group or an ethyl group, a halogen atom, a nitro group, an amino group, a hydroxy group, or the like, as a substituent.

The carboxy group and its salt include functional groups represented by the following general formula (5).
- COO ^- M ⁺ (5)
(M ⁺ represents a monovalent cation.)

Examples of monovalent cations represented by M ⁺ in general formula (5) include, but are not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ .

Examples of sulfo groups and salts thereof include functional groups represented by the following general formula (6).
−SO ₃ ⁻ M ⁺ (6)
(M ⁺ represents a monovalent cation.)

Examples of monovalent cations represented by M ⁺ in general formula (6) include, but are not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ .

Component (C) contains at least one functional group selected from the group consisting of amino groups and salts thereof, and at least one functional group selected from the group consisting of carboxy groups, sulfo groups, and salts thereof. Although it is not particularly limited as long as it has a structure having, it is preferable to have a structure represented by the following general formula (7) or the following general formula (8).
−N(R ³ COO ⁻ M ⁺ ) _n (R ⁴ ) _2-n (7)
-N(R ³ SO ₃ ^- M ⁺ ) _n (R ⁴ ) _2-n (8)
(In formulas (7) and (8) above, R ³ represents a substituted or unsubstituted divalent hydrocarbon group. R ⁴ represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group. , M ⁺ represents a monovalent cation, and n represents an integer of 1 to 2.)

In general formulas (7) and (8) above, the divalent hydrocarbon group represented by R ³ includes an alkanediyl group having 1 to 3 carbon atoms. In general formulas (7) and (8) above, the hydrocarbon group represented by R ⁴ includes the hydrocarbon groups exemplified for R ¹ and R ² in general formulas (3) and (4) above. Hydrocarbon groups similar to hydrogen groups are included. In the general formulas (7) and (8), the monovalent cation represented by M ⁺ is not limited to these, but examples include H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , NH ₄₊ ^are included.

Since the component (C) has the structure represented by the above general formula (7) or the above general formula (8), the component (C) is effectively coordinated to the surface of the molybdenum film. Corrosion can be reduced more effectively.

Component (C) includes, for example, N-(phosphonomethyl)iminodiacetic acid, hydroxyethyliminodiacetic acid, nitrilotriacetic acid, N-(2-carboxyethyl)iminodiacetic acid, ethylenediaminetetraacetic acid, L-glutamic acid diacetic acid tetraacetic acid sodium, glycine-N,N-bis(methylenephosphonic acid), 3,3′,3″-nitrilotripropionic acid, octyliminodipropionate, lauryliminodipropionate, myristyliminodipropionate, stearyl Iminodipropionate, Palmityliminodipropionate, Glycoletherdiaminetetraacetic acid, Hydroxyethylethylenediaminetriacetic acid, 1,3-propanediamine-N,N,N',N'-tetraacetic acid, Triethylenetetramine Hexaacetic acid, dihydroxyethylglycine, dodecylaminoethylaminoethylglycine, (S,S)-ethylenediaminedisuccinic acid trihydrate, iminodiacetic acid, trans-1,2-diaminocyclohexane-N,N,N',N '-tetraacetic acid hydrate, lauramidopropylhydroxysultaine, laurylhydroxysulfobetaine and the like. These components (C) may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of component (C) in the chemical mechanical polishing composition according to the present embodiment is preferably 0.0005% by mass or more when the total mass of the chemical mechanical polishing composition is 100% by mass. , more preferably 0.0008% by mass or more, and particularly preferably 0.001% by mass or more. The content of component (C) in the chemical mechanical polishing composition according to the present embodiment is preferably 5% by mass or less when the total mass of the chemical mechanical polishing composition is 100% by mass. It is preferably 1% by mass or less, and particularly preferably 0.1% by mass or less. When the content of component (C) is within the above range, corrosion of the molybdenum film may be effectively reduced.

1.4. Other Components The chemical mechanical polishing composition according to the present embodiment contains, in addition to the components described above, a liquid medium, a water-soluble polymer, a nitrogen-containing heterocyclic compound, a surfactant, an organic acid and the like, if necessary. Salts, inorganic acids and their salts, basic compounds and the like may be contained.

<Liquid medium>
The chemical mechanical polishing composition according to this embodiment contains a liquid medium. The liquid medium includes water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent compatible with water, and the like. Among these, it is preferable to use water or a mixed medium of water and alcohol, and it is more preferable to use water. Pure water can be preferably used as a raw material of water. The liquid medium may be blended as the balance of each component described above.

<Water-soluble polymer>
The chemical mechanical polishing composition according to this embodiment may contain a water-soluble polymer. The water-soluble polymer may adsorb to the surface of the surface to be polished, reduce polishing friction, and reduce the occurrence of dishing on the surface to be polished.

Specific examples of water-soluble polymers include polycarboxylic acid, polystyrenesulfonic acid, polyacrylic acid, polymethacrylic acid, polyether, polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyethyleneimine, polyallylamine, and hydroxyethylcellulose. . These can be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the water-soluble polymer is preferably 10,000 or more and 1,500,000 or less, more preferably 40,000 or more and 1,200,000 or less. Here, "weight average molecular weight" refers to weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

When the chemical mechanical polishing composition according to the present embodiment contains a water-soluble polymer, the content of the water-soluble polymer is preferably It is 0.001% by mass or more, more preferably 0.002% by mass or more. The content of the water-soluble polymer is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, when the total mass of the chemical mechanical polishing composition is 100% by mass.

<Nitrogen-containing heterocyclic compound>
A nitrogen-containing heterocyclic compound is an organic compound containing at least one heterocyclic ring selected from five- and six-membered heterocyclic rings having at least one nitrogen atom. Specific examples of the heterocyclic ring include five-membered heterocyclic rings such as pyrrole structure, imidazole structure and triazole structure; six-membered heterocyclic rings such as pyridine structure, pyrimidine structure, pyridazine structure and pyrazine structure. The heterocycle may form a condensed ring. Specific examples include an indole structure, an isoindole structure, a benzimidazole structure, a benzotriazole structure, a quinoline structure, an isoquinoline structure, a quinazoline structure, a cinnoline structure, a phthalazine structure, a quinoxaline structure, and an acridine structure. Among heterocyclic compounds having such structures, heterocyclic compounds having a pyridine structure, a quinoline structure, a benzimidazole structure, and a benzotriazole structure are preferred.

Specific examples of nitrogen-containing heterocyclic compounds include aziridine, pyridine, pyrimidine, pyrrolidine, piperidine, pyrazine, triazine, pyrrole, imidazole, indole, quinoline, isoquinoline, benzoisoquinoline, purine, pteridine, triazole, triazolidine, benzotriazole, carboxy Benzotriazoles and derivatives having these skeletons are included. Among these, at least one selected from the group consisting of benzotriazole and triazole is preferred. These nitrogen-containing heterocyclic compounds may be used singly or in combination of two or more.

<Surfactant>
The surfactant is not particularly limited, and anionic surfactants, cationic surfactants, nonionic surfactants and the like can be used. Examples of anionic surfactants include sulfates such as alkyl ether sulfates and polyoxyethylene alkylphenyl ether sulfates; and fluorine-containing surfactants such as perfluoroalkyl compounds. Examples of cationic surfactants include aliphatic amine salts and aliphatic ammonium salts. Nonionic surfactants include, for example, nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adducts, and acetylene alcohol; polyethylene glycol type surfactants and the like. These surfactants may be used singly or in combination of two or more.

<Organic acid and its salt>
The chemical mechanical polishing composition according to the present embodiment includes an organic acid and a salt thereof (excluding the component (C) and the water-soluble polymer having a carboxy group or a sulfo group). )”.) may contain at least one selected from the group consisting of The organic acid and its salt may improve the polishing rate of the molybdenum film due to the synergistic effect with the component (A).

The organic acid and its salt are preferably compounds having a carboxy group and compounds having a sulfo group. Examples of compounds having a carboxy group include stearic acid, lauric acid, oleic acid, myristic acid, alkenylsuccinic acid, lactic acid, tartaric acid, fumaric acid, glycolic acid, phthalic acid, maleic acid, formic acid, acetic acid, oxalic acid, citric acid, acids, malic acid, malonic acid, glutaric acid, succinic acid, benzoic acid, quinolinic acid, quinaldic acid, amidosulfuric acid, propionic acid, trifluoroacetic acid; and salts thereof. Examples of compounds having a sulfo group include alkylbenzenesulfonic acids such as dodecylbenzenesulfonic acid and p-toluenesulfonic acid; alkylnaphthalenesulfonic acids such as butylnaphthalenesulfonic acid; α-olefinsulfonic acids such as tetradecenesulfonic acid; These salts are mentioned. These compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

When the chemical mechanical polishing composition according to the present embodiment contains an organic acid (salt), the content of the organic acid (salt) is It is preferably 0.001% by mass or more, more preferably 0.01% by mass or more. The content of the organic acid (salt) is preferably 5% by mass or less, more preferably 1% by mass or less, when the total mass of the chemical mechanical polishing composition is 100% by mass.

<Inorganic acid and its salt>
The chemical mechanical polishing composition according to the present embodiment may contain at least one selected from the group consisting of inorganic acids and salts thereof (hereinafter also referred to as “inorganic acids (salts)”). The inorganic acid is preferably at least one selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and salts thereof. The inorganic acid may form a salt with a separately added base in the chemical mechanical polishing composition.

<Basic compound>
Basic compounds include organic bases and inorganic bases. Preferred organic bases are amines such as triethylamine, monoethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzylamine, methylamine, ethylenediamine, diglycolamine and isopropylamine. be done. Examples of inorganic bases include ammonia, potassium hydroxide, sodium hydroxide and the like. Among these basic compounds, ammonia and potassium hydroxide are preferred. These basic compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

<Hydrogen peroxide>
The chemical mechanical polishing composition according to the present embodiment may contain hydrogen peroxide, but preferably does not contain hydrogen peroxide. Hydrogen peroxide excessively oxidizes molybdenum and promotes excessive corrosion (etching) of the molybdenum film, so that a good surface to be polished cannot be obtained in many cases.

1.5. pH
The pH of the chemical mechanical polishing composition according to this embodiment is preferably 1 or higher, more preferably 1.5 or higher, and particularly preferably 2 or higher. The pH of the chemical mechanical polishing composition according to this embodiment is preferably 6 or less, more preferably 5 or less, and particularly preferably 4 or less. When the pH of the chemical mechanical polishing composition according to the present embodiment is within the above range, the surface of the molybdenum film is effectively oxidized to facilitate formation of a fragile modified layer, thereby improving the polishing rate of the molybdenum film. There is a tendency.

The pH of the chemical mechanical polishing composition can be adjusted, for example, by adding the aforementioned component (C), organic acid (salt), inorganic acid (salt), basic compound, or the like. One or more can be used.

In the present invention, pH refers to hydrogen ion exponent, and its value can be measured using a commercially available pH meter (for example, desktop pH meter manufactured by Horiba, Ltd.).

1.6. Method for Producing Chemical Mechanical Polishing Composition The method for producing the chemical mechanical polishing composition according to the present embodiment comprises the following components: Component (A), a chelate compound of iron (III) ions as component (B), and, if necessary, It includes a step of dissolving or dispersing component (C) and/or other components in a liquid medium such as water. The method of dissolving or dispersing is not particularly limited, and any method may be applied as long as it can dissolve or disperse uniformly. Also, the mixing order and mixing method of the components described above are not particularly limited.

In the method for producing a chemical mechanical polishing composition according to the present embodiment, it is necessary to add a chelate compound of iron (III) ions as component (B). That is, it is not preferred to add iron(III) ions and a chelating agent separately and allow them to react in the composition to form an iron(III) ion chelate compound in situ. As described above, by using a chelate compound of iron (III) ions as a raw material, the iron (III) ions and the chelating agent can be present in the composition in approximately stoichiometric amounts, resulting in stable polishing. Can express characteristics.

The chemical mechanical polishing composition can also be prepared as a concentrated type stock solution and diluted with a liquid medium such as water at the time of use.

2. Polishing Method A polishing method according to an embodiment of the present invention includes a step of polishing a semiconductor substrate using the chemical mechanical polishing composition described above. The chemical mechanical polishing composition can polish a semiconductor substrate including a molybdenum film and a silicon oxide film at a stable polishing rate while suppressing corrosion of the molybdenum film. Therefore, the semiconductor substrate, which is the object to be processed, preferably has a portion composed of at least one selected from the group consisting of molybdenum and molybdenum alloys. Hereinafter, the polishing method according to this embodiment will be described in detail with reference to FIGS. 1 to 4. FIG.

2.1. Object to be Processed FIG. 1 shows an example of an object to be processed 100 applied to the chemical mechanical polishing method according to the present embodiment.

(1) First, as shown in FIG. 1, a substrate 10 is prepared. The substrate 10 may be composed of, for example, a silicon substrate and a silicon oxide film formed thereon. Furthermore, functional devices such as transistors may be formed on the substrate 10 . Next, a silicon oxide film 12, which is an insulating film, is formed on the substrate 10 by CVD or thermal oxidation.

(2) Next, the silicon oxide film 12 is patterned. Using this as a mask, photolithography is applied to the silicon oxide film 12 to form a via hole 14 .

(3) Next, sputtering is applied to form a barrier metal film 16 on the surface of the silicon oxide film 12 and the inner wall surface of the via hole 14 . Since the electrical contact between molybdenum and silicon is not very good, good electrical contact is achieved by interposing a barrier metal film. Barrier metal film 16 includes titanium and/or titanium nitride.

(4) Next, the molybdenum film 18 is formed by applying the CVD method.

The object to be processed 100 is formed through the above steps.

2.2. Chemical mechanical polishing method 2.2.1. First polishing step In the first polishing step, as shown in FIG. 2, the barrier metal film 16 and the molybdenum film 18 are polished using the aforementioned chemical mechanical polishing composition until the silicon oxide film 12 is exposed. is. Since the chemical mechanical polishing composition described above has an excellent polishing effect not only on the molybdenum film but also on the barrier metal film, the barrier metal film 16 and the molybdenum film 18 can be polished and removed in the same processing step. .

2.2.2. Second polishing step The second polishing step, as shown in FIG. 3, is a step of simultaneously polishing the barrier metal film 16, the molybdenum film 18 and the silicon oxide film 12 using the chemical mechanical polishing composition described above. be. Since the chemical mechanical polishing composition described above has non-selective polishing properties for molybdenum films and silicon oxide films, it is possible to obtain a finished surface with extremely excellent flatness in the second polishing treatment step.

Here, in the chemical mechanical polishing composition used in the second polishing process, the concentration of the component (B) contained in the chemical mechanical polishing composition used in the first polishing process is within the composition range described above. may be changed as appropriate and used. By adjusting the concentration of the component (B) so that the ratio of the polishing rate of the silicon oxide film to the polishing rate of the molybdenum film is 1 or more, excessive polishing of the molybdenum film relative to the silicon oxide film can be sufficiently suppressed. , a semiconductor substrate including a molybdenum film and a silicon oxide film can be polished at a stable polishing rate. Also, by adjusting the zeta potential or degree of association in the component (A) in the chemical mechanical polishing composition, the ratio of the polishing rate of the silicon oxide film to the polishing rate of the molybdenum film can be adjusted to be 1 or more. .

2.2.3. Chemical Mechanical Polishing Apparatus In the first polishing process and the second polishing process, for example, a chemical mechanical polishing apparatus 200 as shown in FIG. 4 can be used. FIG. 4 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. FIG. Slurry 44 is supplied from slurry supply nozzle 42, and carrier head 52 holding semiconductor substrate 50 is brought into contact while rotating turntable 48 on which polishing cloth 46 is adhered. 4 also shows the water supply nozzle 54 and the dresser 56. As shown in FIG.

The polishing load of the carrier head 52 can be selected within the range of 10-980 hPa, preferably 30-490 hPa. Also, the rotation speed of the turntable 48 and the carrier head 52 can be appropriately selected within the range of 10 to 400 rpm, preferably 30 to 150 rpm. The flow rate of the slurry 44 supplied from the slurry supply nozzle 42 can be selected within the range of 10-1,000 mL/min, preferably 50-400 mL/min.

Examples of commercially available chemical mechanical polishing apparatuses include models "EPO-112" and "EPO-222" manufactured by Ebara Corporation; models "LGP-510" and "LGP-552" manufactured by Lapmaster SFT; Models "Mirra" and "Reflexion" manufactured by Material Co., Ltd. may be mentioned.

3. Examples Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. "Parts" and "%" in the examples are based on mass unless otherwise specified.

3.1. Preparation of silica particle aqueous dispersion 3.1.1. Preparation of Aqueous Dispersion A An aqueous dispersion A containing 15.5% by mass of silica particles and pH 7.6 was obtained according to Example 3 described in WO 2008/123373.
As a result of measuring the water dispersion A by a dynamic light scattering method (manufactured by Malvern, model "Zetasizer Ultra"), the average secondary particle diameter in terms of volume of the silica particles contained in the water dispersion A was 17.3 nm. there were.
Further, the water dispersion A was photographed at a magnification of 30,000 times using a transmission electron microscope (TEM) (manufactured by Hitachi High-Tech Co., Ltd., model "H-7650"). The distance of the longest straight line among the straight lines connecting the ends of the particle images was measured, and the average value of the values was calculated as the average primary particle size. The average primary particle size of the silica particles contained in the aqueous dispersion A calculated in this manner was 15.8 nm.
Using the average primary particle size and average secondary particle size calculated by the above method, the degree of association was calculated by the following formula, and the degree of association of the silica particles contained in the aqueous dispersion A was 1.1. there were.
Degree of association = (average secondary particle size) / (average primary particle size)
Hereinafter, the average primary particle size, average secondary particle size and degree of association of silica particles contained in each aqueous dispersion were measured and calculated in the same manner.

3.1.2. Preparation of Aqueous Dispersion B 2520 g of Aqueous Dispersion A (15.5% colloidal silica dispersion) was heated to 60°C. After that, 15.5 g of (3-triethoxysilyl) propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 60°C for 4 hours. An aqueous dispersion B containing modified silica particles was obtained.

3.1.3. Preparation of Water Dispersion C To 2520 g of water dispersion A (15.5% colloidal silica dispersion), 25% aqueous ammonia (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9. After that, 3.9 g of a (3-triethoxysilyl)mercapto group-containing silane coupling agent (trade name “KBM-803” manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise, and the mixture was stirred at 60° C. for 2 hours. After that, 50 g of hydrogen peroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added, refluxed for 8 hours under normal pressure, and a water dispersion containing silica particles surface-modified with a sulfo group having an average secondary particle diameter of 17.3 nm. Got a body C.

3.1.4. Preparation of Aqueous Dispersion D PL-1 (manufactured by Fuso Chemical Industry Co., Ltd., 12% colloidal silica dispersion) was used as aqueous dispersion D as it was. When measured by the above method, the average secondary particle size of the silica particles contained in the aqueous dispersion D was 30.1 nm.

3.1.5. Preparation of Water Dispersion E To 3250 g of PL-1 (12% colloidal silica dispersion manufactured by Fuso Chemical Industry Co., Ltd.), 25% aqueous ammonia (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9. After that, 3.9 g of a (3-triethoxysilyl)mercapto group-containing silane coupling agent (trade name “KBM-803” manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise, and the mixture was stirred at 60° C. for 2 hours. After that, 50 g of hydrogen peroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added, refluxed for 8 hours under normal pressure, and a water dispersion containing silica particles surface-modified with a sulfo group having an average secondary particle diameter of 30.1 nm. Got body E.

3.1.6. Preparation of Water Dispersion F 1950 g of PL-3 (19.5% colloidal silica dispersion manufactured by Fuso Chemical Industry Co., Ltd.) was heated to 60°C. After that, 15.5 g of (3-triethoxysilyl) propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 60°C for 4 hours. An aqueous dispersion F containing modified silica particles was obtained.

3.1.7. Preparation of Water Dispersion G PL-3 (19.5% colloidal silica dispersion manufactured by Fuso Chemical Industry Co., Ltd.) was added with 25% aqueous ammonia (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to adjust the pH to 9. . After that, 3.9 g of a (3-triethoxysilyl)mercapto group-containing silane coupling agent (trade name “KBM-803” manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise, and the mixture was stirred at 60° C. for 2 hours. After that, 50 g of hydrogen peroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added, refluxed for 8 hours under normal pressure, and a water dispersion containing silica particles surface-modified with a sulfo group having an average secondary particle diameter of 58.2 nm. Got body G.

3.1.8. Preparation of Water Dispersion H To 1950 g of PL-2L (manufactured by Fuso Chemical Industries, Ltd., 20% colloidal silica dispersion), 25% aqueous ammonia (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9. After that, 3.9 g of a (3-triethoxysilyl)mercapto group-containing silane coupling agent (trade name “KBM-803” manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise, and the mixture was stirred at 60° C. for 2 hours. After that, 50 g of hydrogen peroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added, refluxed for 8 hours under normal pressure, and a water dispersion containing silica particles surface-modified with a sulfo group having an average secondary particle diameter of 22.5 nm. Got body H.

3.1.9. Preparation of Water Dispersion I 1950 g of PL-2L (20% colloidal silica dispersion manufactured by Fuso Chemical Industry Co., Ltd.) was heated to 60°C. After that, 15.5 g of (3-triethoxysilyl) propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 60°C for 4 hours. An aqueous dispersion I containing modified silica particles was obtained.

3.1.10. Preparation of Water Dispersion J To 6510 g of PL-06L (manufactured by Fuso Chemical Industries, Ltd., 6% colloidal silica dispersion), 25% aqueous ammonia (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was added to adjust the pH to 9. After that, 3.9 g of a (3-triethoxysilyl)mercapto group-containing silane coupling agent (trade name “KBM-803” manufactured by Shin-Etsu Chemical Co., Ltd.) was added dropwise, and the mixture was stirred at 60° C. for 2 hours. After that, 50 g of hydrogen peroxide (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) was added, refluxed for 8 hours under normal pressure, and a water dispersion containing silica particles surface-modified with a sulfo group having an average secondary particle diameter of 7.4 nm. I got a body J.

3.1.11. Preparation of Water Dispersion K 6510 g of PL-06L (manufactured by Fuso Chemical Industries, Ltd., 6% colloidal silica dispersion) was heated to 60.degree. After that, 15.5 g of (3-triethoxysilyl) propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was further stirred at 60°C for 4 hours. An aqueous dispersion K containing modified silica particles was obtained.

3.1.12. Preparation of Water Dispersion L A mixture of 70 g of methanol and 11.3 g of 3-aminopropyltriethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added dropwise to 2520 g of water dispersion A (15.5% colloidal silica dispersion). , and refluxed for 2 hours under normal pressure. After that, pure water was added dropwise while keeping the volume constant, and when the temperature at the top of the column reached 100°C, the dropwise addition of pure water was terminated. An aqueous dispersion L containing particles was obtained.

3.2. Preparation of Component (C) 3.2.1. Preparation of octyliminodipropionate As alkylamine, octylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) 2.5 g (19.5 mmol), 3-chloropropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) 5.7 g (52.9 mmol) ) was added to a mixed solution of 5.0 mL of water and 32 mL of ethanol (manufactured by Kanto Kagaku Co., Ltd.) and stirred under reflux for 6 hours. During this reflux stirring, 7.8 mL of potassium hydroxide aqueous solution (5.0 mol/L) prepared from potassium hydroxide (manufactured by Kanto Kagaku Co., Ltd.) was added to adjust the pH. The solution was then cooled to 4° C. to form a precipitate. After washing the generated precipitate with ethanol, it was filtered and dried under reduced pressure to collect a solid to obtain octyliminodipropionate.

3.2.2. Preparation of lauryliminodipropionate 3.6 g (19.5 mmol) of laurylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used as the alkylamine, but the above “3.2.1. Preparation” to obtain lauryl imino dipropionate.

3.2.3. Preparation of myristyliminodipropionate As the alkylamine, 4.2 g (19.5 mmol) of myristylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used, but the above "3.2.1. Octyliminodipropionate Preparation” to obtain myristyliminodipropionate.

3.2.4. Preparation of Palmityliminodipropionate Salt Other than using 4.7 g (19.5 mmol) of palmitylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) as the alkylamine, the above "3.2.1. Octyliminodipropionic acid Preparation of salt” to obtain palmityliminodipropionate.

3.2.5. Preparation of stearyliminodipropionate As the alkylamine, 5.3 g (19.5 mmol) of stearylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used. Preparation” to obtain stearyliminodipropionate.

3.3. Preparation of chemical mechanical polishing composition Each component was mixed so as to have the composition shown in Tables 1 to 3, and an aqueous potassium hydroxide solution (Kanto Chemical Co., Ltd., product name “48% potassium hydroxide aqueous solution”), ammonia water (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., product name “ammonia water”, maleic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., product name “maleic acid”), acetic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “acetic acid”), and fumaric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “fumaric acid”) are added as necessary. Pure water was added so that the total amount of all components was 100% by mass to prepare the chemical mechanical polishing compositions of each example and each comparative example. Tables 1 to 3 also show the results of measuring the zeta potential of the abrasive grains of the chemical mechanical polishing composition using a zeta potential measuring device (manufactured by Dispersion Technology Inc., model "DT300").

3.4. Evaluation method 3.4.1. Polishing rate evaluation of molybdenum film and silicon oxide film Using the chemical mechanical polishing composition prepared above, a 12-inch diameter wafer with a 200 nm molybdenum film and a 12-inch diameter wafer with a 1000 nm silicon oxide film (p-TEOS film) were used as objects to be treated, chemical mechanical polishing tests were performed under the following conditions, and then brush scrub cleaning was performed under the following conditions.
(polishing conditions)
・Polishing device: Model “Reflexion-LK” manufactured by Applied Materials
・ Polishing pad: Fuji Spinning Co., Ltd., “Porous polyurethane pad; H800-type1 (3-1S) 775”
・Chemical mechanical polishing composition supply rate: 300 mL/min ・Surface plate rotation speed: 100 rpm
・Head rotation speed: 90 rpm
・Head pressing pressure: 2 psi
・Polishing time: 60 seconds ・Polishing speed (nm/min) = (thickness of film before polishing - thickness of film after polishing) / polishing time (brush scrub cleaning conditions)
・Processing agent: pure water ・Upper brush rotation speed: 400 rpm
・Lower brush rotation speed: 400 rpm
・Substrate rotation speed: 50 rpm
・Treatment agent supply rate: 1200 mL/min

The thickness of the molybdenum film is determined by measuring the resistance by the DC 4-probe method using a resistivity measuring device (manufactured by KLA-Tencor, model "RS-100"), and from the sheet resistance value and the volume resistivity of molybdenum. It was calculated by the following formula.
Molybdenum film thickness (nm)=[volume resistivity of molybdenum film (Ω·m)÷sheet resistance value (Ω/sq)]×10 ⁹
In addition, the thickness of the silicon oxide film was measured by an optical film thickness measuring device (manufactured by KLA-Tencor, model "ASET F5x").

The evaluation criteria for the molybdenum film polishing rate are as follows. Tables 1 to 3 also show the evaluation results of the molybdenum film polishing rate.
(Evaluation criteria)
AA: When the polishing rate was 2.5 nm/min or more and less than 30 nm/min, the polishing rate was appropriate and judged to be very good.
A: When the polishing rate is 30 nm/min or more and less than 40 nm/min, the polishing rate is high and careful control is required in mass production, but it is judged to be good because it can be put to practical use.
B: When the polishing rate was less than 2.5 nm/min, the polishing rate was so low that it was difficult to put into practical use, so it was judged to be unsatisfactory. Alternatively, when the polishing rate was 40 nm/min or more, the polishing rate was so high that it could not be controlled during mass production, making it difficult to practically use.

Using the molybdenum film polishing speed and the silicon oxide film polishing speed calculated above, the polishing speed ratio was calculated according to the following equation.
Polishing speed ratio=Polishing speed of silicon oxide film (nm/min)/Polishing speed of molybdenum film (nm/min)
(Evaluation criteria)
AA: When the polishing rate ratio was 1 or more, excessive polishing of the molybdenum film with respect to the silicon oxide film was sufficiently suppressed, so it was judged to be very good.
A: When the polishing speed ratio is 0.5 or more and less than 1, the polishing speed of the molybdenum film with respect to the silicon oxide film is large, and care must be taken in controlling it in mass production. .
B: When the polishing rate ratio was less than 0.5, the molybdenum film was excessively polished with respect to the silicon oxide film, and it was judged to be defective because it was difficult to put into practical use.

3.4.2. Evaluation of Etching Rate of Molybdenum Film The chemical mechanical polishing composition prepared above was heated to 60° C., and a wafer piece with a molybdenum film of 200 nm cut to 30 mm×10 mm was immersed for 5 minutes. After that, the wafer piece was taken out and washed with running water, and the thickness of the molybdenum film was measured in the same manner as in "3.4.1. Polishing rate evaluation of molybdenum film and silicon oxide film" above. Then, the etching rate was calculated from the change in the thickness of the molybdenum film before and after the immersion using the following formula.
Molybdenum film etching rate (nm/min)=(thickness of molybdenum film before etching (nm)−thickness of molybdenum film after etching (nm))/etching time (min)

The evaluation criteria for the etching rate of the molybdenum film are as follows. Tables 1 to 3 also show the evaluation results of the etching rate of the molybdenum film.
(Evaluation criteria)
· A: When the etching rate was less than 0.1 nm/min, it was judged to be good.
B: When the etching rate was 0.1 nm/min or more, the etching rate was too high to be practical, so it was judged to be unsatisfactory.

3.5. Evaluation Results Tables 1 to 3 show the composition of the chemical mechanical polishing composition used in each example and each comparative example and each evaluation result.

The following products or reagents were used for each component in Tables 1 to 3 above.
<Component (A)>
Aqueous dispersions A to L: Aqueous dispersions A to L prepared in the above section "3.1. Preparation of silica particle aqueous dispersion"
<Component (B)>
・ Ethylenediaminetetraacetic acid iron ammonium dihydrate: manufactured by Cherest Co., Ltd., trade name “Cherest FN”
・ Iron citrate trihydrate: manufactured by Fuso Chemical Industry Co., Ltd., trade name “Fuji iron citrate”
Acetylacetone iron: manufactured by Kishida Chemical Co., Ltd., trade name "acetylacetonate iron (III)"
・ Diethylenetriamine pentaacetic acid iron diammonium salt: manufactured by Cherest Co., Ltd., trade name “Cherest FNZ-50”
・ 1,3-Diaminopropanetetraacetic acid ferric ammonium monohydrate: manufactured by Cherest Co., Ltd., trade name “Cherest PD-FN”
・ Iron (III) nitrate nonahydrate: manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name “Iron (III) nitrate nonahydrate”
<Component (C)>
- Octyliminodipropionate: Octyliminodipropionate prepared in the above section "3.2. Preparation of component (C)" - Lauryliminodipropionate: Above "3.2. Component (C)" Lauryliminodipropionate/myristyliminodipropionate prepared in the section "Preparation of": Myristyliminodipropionate/palmitylimino prepared in the above section "3.2. Preparation of component (C)" Dipropionate: Palmityliminodipropionate and stearyliminodipropionate prepared in the section "3.2. Preparation of component (C)" above: Preparation of component (C) above Stearyliminodipropionate and dodecylaminoethylaminoethylglycine prepared in the section ": manufactured by Sanyo Chemical Industries, Ltd., trade name "Lebon S"
・ Lauramidopropyl hydroxysultaine: Kawaken Fine Chemicals Co., Ltd., trade name “Softazolin LSB-R”
- Lauryl hydroxysulfobetaine: manufactured by Kao Corporation, trade name "Amphitol 20HD"
<Other additives>
・ Dodecylbenzenesulfonate ammonium salt: manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name “ammonium dodecylbenzenesulfonate”
・Hydrogen peroxide: manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name “hydrogen peroxide”
・ Orthoperiodic acid: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name “orthoperiodic acid”
・ Ammonium peroxodisulfate: manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name “ammonium peroxodisulfate”
・ Iron sulfate (II) heptahydrate: manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd., trade name “Iron (II) sulfate heptahydrate”
・ Ethylenediaminetetraacetic acid diammonium salt: manufactured by Cherest Co., Ltd., trade name “Cherest 2N-40”
・ Diethylenetriaminepentaacetic acid triammonium salt: manufactured by Cherest Co., Ltd., trade name “Cherest HP-3NZ50”

According to the chemical mechanical polishing compositions of Examples 1 to 26 in which the component (A) and the component (B) were used in combination, the molybdenum film was oxidized to polish both the molybdenum film and the silicon oxide film at a stable polishing rate. It can be seen that polishing can be performed, excessive reaction between molybdenum and anion species can be prevented, and corrosion of the molybdenum film can be reduced.

On the other hand, according to the chemical mechanical polishing compositions of Comparative Examples 1 and 2 containing iron (III) nitrate nonahydrate, which is not a chelate compound, the surface of the molybdenum film is likely to be corroded, so that it can be put to practical use. I know it's difficult. It can be seen that the chemical mechanical polishing compositions of Comparative Examples 3 to 7, which do not contain the component (B), are difficult to put to practical use because the molybdenum film polishing rate is too low or too high. Chemical-mechanical polishing of Comparative Examples 8-9 in which iron (III) compounds and chelating agents were added separately and reacted in the composition to form iron (III) ion chelates in situ It can be seen that the excessive presence of iron (III) ions in the composition makes the surface of the molybdenum film susceptible to corrosion, making it difficult to put it to practical use.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same function, method, and result, or configurations that have the same purpose and effect). Moreover, the present invention includes configurations in which non-essential portions of the configurations described in the embodiments are replaced. Moreover, the present invention includes a configuration that achieves the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the present invention includes configurations obtained by adding known techniques to the configurations described in the embodiments.

DESCRIPTION OF SYMBOLS 10... Substrate, 12... Silicon oxide film, 14... Wiring groove, 16... Barrier metal film, 18... Molybdenum film, 42... Slurry supply nozzle, 44... Slurry (chemical mechanical polishing composition), 46... Polishing pad , 48... Turntable, 50... Semiconductor substrate, 52... Carrier head, 54... Water supply nozzle, 56... Dresser, 100... Object to be processed, 200... Polishing apparatus

Claims

containing abrasive grains (A) and an iron (III) compound (B),
A chemical mechanical polishing composition, wherein the iron (III) compound (B) is a chelate compound.
A compound (C ), the chemical mechanical polishing composition according to claim 1 .
The chemical mechanical polishing composition according to claim 1 or 2, wherein the abrasive grains (A) in the chemical mechanical polishing composition have an average secondary particle size of 5 nm or more and 100 nm or less.
4. The chemical mechanical polishing composition according to claim 1, wherein the degree of association of the abrasive grains (A) in the chemical mechanical polishing composition is 1.0 or more and 2.0 or less. .
The chemical mechanical polishing composition according to any one of claims 1 to 4, wherein the abrasive grains (A) in the chemical mechanical polishing composition have a zeta potential of less than 0 mV.
Claims 1 to 3, wherein the abrasive grains (A) have at least one functional group selected from the functional groups represented by the following general formula (1) and the following general formula (2): 6. The chemical mechanical polishing composition according to any one of 5.
- SO 3 - M + (1)
- COO - M + (2)
(In formulas (1) and (2) above, M + represents a monovalent cation.)
The chemical mechanical polishing composition according to any one of claims 1 to 6, which has a pH of 1 or more and 6 or less.
A polishing method comprising the step of polishing a semiconductor substrate using the chemical mechanical polishing composition according to any one of claims 1 to 7.
The polishing method according to claim 8, wherein the semiconductor substrate has a portion composed of at least one selected from the group consisting of molybdenum and molybdenum alloys.
Dissolving or dispersing abrasive grains (A) and iron (III) compound (B) in a liquid medium,
A method for producing a chemical mechanical polishing composition, wherein the iron (III) compound (B) is a chelate compound.