Chemical mechanical polishing composition and polishing method

Abstract

To provide a composition for chemical mechanical polishing that makes it possible to polish a molybdenum film and a silicon oxide film at a stable polishing rate and to inhibit corrosion of the molybdenum film and generation of defects in the silicon oxide film.SOLUTION: The composition for chemical mechanical polishing contains abrasive grains and an iron (III) compound, where the abrasive grains have at least one of functional groups represented by the general formula (1), -SO3-M+, and the general formula (2), -COO-M+. In the formulas (1) and (2), M+ represents a monovalent cation.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a chemical mechanical polishing composition and a polishing method using the same. [Background technology]

[0002] With the advancement of semiconductor integrated circuit manufacturing technology, there is a demand for higher integration and faster operation of semiconductor elements. Accordingly, the flatness of the semiconductor substrate surface required in the manufacturing process of fine circuits in semiconductor elements is becoming more stringent, and chemical mechanical polishing (CMP) has become an essential technology in the manufacturing process of semiconductor elements.

[0003] Tungsten, which has excellent embedding properties, is often used in via holes that electrically connect wiring in the vertical and horizontal directions on semiconductor substrates manufactured through CMP. 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 as a chemical mechanical polishing composition used to polish tungsten films (see, for example, Patent Document 1). Furthermore, in recent years, molybdenum has been used instead of tungsten because it has lower hardness and is easier to process than tungsten, and chemical mechanical polishing compositions for polishing molybdenum films have been investigated (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2008-503875 [Patent Document 2] International Publication No. 2013 / 188296 Summary of the Invention [Problem to be solved by the invention]

[0005] In CMP for forming a via hole using molybdenum, it is necessary to polish and planarize the embedded molybdenum film and the surrounding silicon oxide film in the same process. To achieve this, there is a demand for a chemical mechanical polishing composition that can polish the molybdenum film and the silicon oxide film at a stable polishing rate while suppressing corrosion of the molybdenum film and the occurrence of defects in the silicon oxide film.

[0006] Some aspects of the present invention provide a chemical mechanical polishing composition that can polish molybdenum films and silicon oxide films at a stable polishing rate and can suppress corrosion of the molybdenum film and the occurrence of defects in the silicon oxide film. [Means for solving the problem]

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized as any of the following aspects.

[0008] One aspect of the chemical mechanical polishing composition of the present invention is Contains abrasive grains (A) and an iron (III) compound (B), The abrasive grains (A) have at least one functional group selected from the functional group represented by the following general formula (1) and the functional group represented by the following general formula (2). -SO3 - M + ·····(1) -COO - M + ·····(2) (In the above formulas (1) and (2), M + represents a monovalent cation.)

[0009] In one embodiment of the chemical mechanical polishing composition, It may further contain a compound (C) having at least one functional group selected from the group consisting of an amino group and a salt thereof, and at least one functional group selected from the group consisting of a carboxy group, a sulfo group, and a salt thereof.

[0010] In any one of the embodiments 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.

[0011] In any one of the embodiments of the chemical mechanical polishing composition, The degree of association of the abrasive grains (A) in the chemical mechanical polishing composition may be 1.0 or more and 2.0 or less.

[0012] In any one of the embodiments of the chemical mechanical polishing composition, The abrasive grains (A) in the chemical mechanical polishing composition may have a zeta potential of less than 0 mV.

[0013] In any one of the embodiments of the chemical mechanical polishing composition, The pH may be 1 or more and 6 or less.

[0014] One aspect of the polishing method according to the present invention is to The method includes polishing a semiconductor substrate using the chemical mechanical polishing composition of any one of the above embodiments.

[0015] In one embodiment of the polishing method, The semiconductor substrate may include a portion made of at least one material selected from the group consisting of molybdenum and molybdenum alloys. [Effects of the Invention]

[0016] By using the chemical mechanical polishing composition of the present invention, it is possible to polish a semiconductor substrate containing a molybdenum film and a silicon oxide film at a stable polishing rate while suppressing corrosion of the molybdenum film and the occurrence of defects in the silicon oxide film. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view schematically showing a target object suitable for use in a polishing process according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically showing the object to be polished at the end of a first polishing step. [Figure 3] FIG. 10 is a cross-sectional view schematically showing the object to be polished at the end of a second polishing step. [Figure 4] FIG. 1 is a perspective view schematically illustrating a chemical mechanical polishing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0018] Preferred embodiments of the present invention will be described in detail below. Note that the present invention is not limited to the following embodiments, and various modifications are also included within the scope of the present invention.

[0019] In this specification, a 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.

[0020] 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) (also referred to herein as "component ( and the abrasive grains (A) have at least one functional group selected from the functional group represented by the following general formula (1) and the functional group represented by the following general formula (2). -SO3 - M + ·····(1) -COO - M + ·····(2) (In the above formulas (1) and (2), M + represents a monovalent cation.)

[0021] Each component contained in the chemical mechanical polishing composition according to this embodiment will be described in detail below.

[0022] 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, with inorganic grains being preferred. Examples of inorganic grains include inorganic oxide grains such as silica, ceria, alumina, zirconia, and titania, with silica grains being preferred. Examples of silica grains include fumed silica and colloidal silica, with colloidal silica being preferred.

[0023] The shape of component (A) is not particularly limited, and it may be spherical, cocoon-shaped, chain-like, or have multiple protrusions on its surface. Abrasive grains having multiple protrusions on their surface can be produced, for example, by applying the methods described in JP-A-2007-153732 and JP-A-2013-121631.

[0024] 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 component (A) is within this range, the electrostatic repulsion between the abrasive grains effectively prevents aggregation of the particles, improving the storage stability of the chemical mechanical polishing composition and enabling the polishing of semiconductor substrates containing molybdenum films and silicon oxide films at a more stable polishing rate. Zeta potential measuring devices include the "ELSZ-2000ZS" manufactured by Otsuka Electronics Co., Ltd. and the "Zetasizer" manufactured by Malvern. Ultra" manufactured by Dispersion Technology Inc., and "DT300" manufactured by Dispersion Technology Inc.

[0025] At least a portion of the surface of component (A) has at least one functional group selected from the functional group represented by the following general formula (1) and the functional group represented by the following general formula (2) (hereinafter also referred to as the "specific functional group"). -SO3 - M + ·····(1) -COO - M + ·····(2) (In the above formulas (1) and (2), M + represents a monovalent cation.)

[0026] The abrasive grains, at least a portion of whose surface is modified with a specific functional group, have a larger absolute value of zeta potential than the abrasive grains that are not surface-modified with a specific functional group, and the electrostatic repulsion between the abrasive grains is increased. As a result, the dispersibility of the abrasive grains in the chemical mechanical polishing composition is improved, and therefore, semiconductor substrates containing molybdenum films and silicon oxide films can be polished at a stable polishing rate while reducing the occurrence of polishing scratches and dishing.

[0027] In the above general formula (1), M + Examples of monovalent cations represented by the formula include, but are not limited to, H + , Li + , Na + , K. + , NH4 + In other words, the functional group represented by the general formula (1) can be rephrased as "at least one functional group selected from the group consisting of sulfo groups and salts thereof." Here, "salts of sulfo groups" refer to functional groups that convert hydrogen ions contained in sulfo groups (-SO3H) into Li + , Na + , K. + , NH4 + It refers to a functional group substituted with a monovalent cation such as the above. Component (A) is an abrasive grain having a functional group represented by the general formula (1) fixed to its surface via a covalent bond, but does not include abrasive grains having a compound having a functional group represented by the general formula (1) physically or ionically adsorbed to their surface.

[0028] Component (A) having a functional group represented by the general formula (1) can be produced as follows. First, silica prepared by a known method and a mercapto group-containing silane coupling agent are thoroughly 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, an appropriate amount of hydrogen peroxide is added and the mixture is left to stand for a sufficient period of time to obtain component (A) having a functional group represented by the general formula (1).

[0029] The zeta potential of component (A) having a functional group represented by the general formula (1) is negative in the chemical mechanical polishing composition, and this negative potential is preferably less than 0 mV, more preferably -10 mV or less, and particularly preferably -15 mV or less. When the zeta potential of component (A) is within this range, the electrostatic repulsion between the abrasive grains effectively prevents particle aggregation, and semiconductor substrates containing molybdenum films and silicon oxide films can be polished at a more stable polishing rate. The zeta potential measuring device described above can be used. The zeta potential of component (A) having a functional group represented by the 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.

[0030] In the above general formula (2), M + Examples of monovalent cations represented by the formula include, but are not limited to, H + , Li + , Na + , K. + , NH4 + In other words, the functional group represented by the general formula (2) can be rephrased as "at least one functional group selected from the group consisting of a carboxy group and its salts." Here, the "salt of a carboxy group" refers to a functional group in which the hydrogen ion contained in the carboxy group (-COOH) is converted to Li + , Na + , K. + , NH4+ The term "component (A)" refers to a functional group substituted with a monovalent cation such as . Component (A) having a functional group represented by general formula (2) above is an abrasive grain having a functional group represented by general formula (2) fixed to its surface via a covalent bond, but does not include abrasive grains having a compound having a functional group represented by general formula (2) physically or ionically adsorbed to their surface.

[0031] Component (A) having a functional group represented by the general formula (2) can be produced as follows. First, silica prepared by a known method and a carboxylic acid anhydride-containing silane coupling agent are thoroughly stirred in a basic medium, and the carboxylic acid anhydride-containing silane coupling agent is covalently bonded to the surface of the abrasive grains, thereby obtaining abrasive grains having a functional group represented by the general formula (2). Here, examples of the carboxylic acid anhydride-containing silane coupling agent include 3-(triethoxysilyl)propylsuccinic anhydride.

[0032] The zeta potential of component (A) having a functional group represented by the general formula (2) is negative in the chemical mechanical polishing composition, and this negative potential is preferably less than 0 mV, more preferably -10 mV or less, and particularly preferably -15 mV or less. When the zeta potential of component (A) is within this range, the electrostatic repulsion between the abrasive grains effectively prevents particle aggregation, and semiconductor substrates containing molybdenum films and silicon oxide films can be polished at a more stable polishing rate. The zeta potential measuring device described above can be used. The zeta potential of component (A) having a functional group represented by the general formula (2) can be adjusted by appropriately increasing or decreasing the amount of the carboxylic acid anhydride-containing silane coupling agent or the like added.

[0033] The average secondary particle diameter 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 diameter 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 diameter of component (A) is within this range, the small particle size reduces mechanical polishing performance, but the increased surface free energy improves reactivity with molybdenum and silicon oxide, enabling polishing of semiconductor substrates containing molybdenum and silicon oxide films at a more stable polishing rate and resulting in a chemical mechanical polishing composition with excellent stability and free from particle settling and separation. The average secondary particle diameter of component (A) in the chemical mechanical polishing composition is the volume-based average particle diameter measured using a particle size distribution analyzer that uses dynamic light scattering. An example of such a particle size distribution analyzer is the "Zetasizer Ultra" manufactured by Malvern.

[0034] 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 averaging the particle sizes of 50 particles of component (A) by observation with a transmission electron microscope.

[0035] From the average secondary particle size and average primary particle size measured as described above, the degree of association, which is an index showing the degree of aggregation of component (A) in the chemical mechanical polishing composition, can be calculated using the following calculation formula. Degree of association = (average secondary particle diameter (nm)) / (average primary particle diameter (nm))

[0036] The degree of association of component (A) in the chemical mechanical polishing composition is preferably 1.0 or more, more preferably 1.01 or more. The degree of association 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 component (A) is within this range, aggregation of component (A) is suppressed and the component (A) is dispersed in the chemical mechanical polishing composition, and the surface free energy of the particles is increased, improving reactivity with molybdenum and silicon oxide. This may enable semiconductor substrates containing molybdenum films and silicon oxide films to be polished at a more stable polishing rate.

[0037] The content of component (A) in the chemical mechanical polishing composition of this embodiment is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and particularly preferably 0.5 mass% or more, based on 100 mass% of the total mass of the chemical mechanical polishing composition. The content of component (A) in the chemical mechanical polishing composition of this embodiment is preferably 10 mass% or less, more preferably 8 mass% or less, and particularly preferably 6 mass% or less, based on 100 mass% of the total mass of the chemical mechanical polishing composition. When the content of component (A) is within this range, semiconductor substrates containing molybdenum films and silicon oxide films can be polished at a stable polishing rate, and the storage stability of the chemical mechanical polishing composition may be improved.

[0038] 1.2.Component (B) The chemical mechanical polishing composition according to this embodiment contains an iron(III) compound (B). Component (B) oxidizes the surface of the molybdenum film to create a brittle modified layer, thereby accelerating the polishing of the molybdenum film.

[0039] As component (B), any organic acid iron (III) salt or The component (B) may be either an iron (III) salt of an inorganic acid or an iron (III) salt. Component (B) is preferably a chelate compound of iron (III) ions.

[0040] The chelate compound of iron(III) ions can be prepared by reacting iron(III) ions with a chelating agent. When preparing the chemical mechanical polishing composition of this embodiment, a chelate compound of iron(III) ions may be added as component (B). Alternatively, the chelate compound of iron(III) ions may be separately added to the composition and reacted with the chelating agent to produce the chelate compound of iron(III) ions.

[0041] The chelating agent is not particularly limited as long as it is a compound that can coordinate to iron (III) ions as a bidentate or higher ligand. For example, chelating agents such as (polyvalent) carboxylic acids, (polyvalent) aminocarboxylic acids, (polyvalent) oxycarboxylic acids, (polyvalent) phosphonic acids, and salts thereof can be used. Preferred examples of the chelating agent 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.

[0042] For example, the chemical mechanical polishing composition for polishing tungsten described in JP-A-2008-503875 uses an iron (III) compound, specifically iron (III) nitrate. However, iron (III) nitrate cannot be used in the chemical mechanical polishing composition of this embodiment. If iron (III) nitrate is used, the surface of the molybdenum film would be excessively oxidized by the action of nitrate ions, making the molybdenum portion more susceptible to corrosion. Therefore, it is preferable that the chemical mechanical polishing composition of this embodiment contain as little nitrate ions as possible. The nitrate ion concentration in the chemical mechanical polishing composition of this embodiment is preferably 200 ppm or less, more preferably 190 ppm or less, and particularly preferably 180 ppm or less. Even if the chemical mechanical polishing composition of this embodiment contains nitrate ions, a concentration of 0.005 ppm or more is acceptable, and even a concentration of 0.01 ppm or more is practically acceptable.

[0043] The content of component (B) in the chemical mechanical polishing composition according to this embodiment is preferably 0.001% by mass or more, more preferably 0.05% by mass or more, and particularly preferably 0.01% by mass or more, based on 100% by mass of the total mass of the chemical mechanical polishing composition. The content of component (B) in the chemical mechanical polishing composition according to this embodiment is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.5% by mass or less, based on 100% by mass of the total mass of the chemical mechanical polishing composition. When the content of component (B) is within this range, it is possible to oxidize the molybdenum film to promote polishing, and it is also possible to prevent excessive reaction between molybdenum and anion species, thereby reducing the occurrence of corrosion of the molybdenum film.

[0044] 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. When the concentration of iron(III) ions in the chemical mechanical polishing composition of this embodiment is within the above range, the molybdenum film can be oxidized to promote polishing, and excessive reaction between molybdenum and anion species can be prevented, which may reduce the occurrence of corrosion of the molybdenum film.

[0045] 1.3.Component (C) The chemical mechanical polishing composition of this embodiment may contain a compound (C) (also referred to herein as "component (C)") having at least one functional group selected from the group consisting of an amino group and its salts, and at least one functional group selected from the group consisting of a carboxy group, a sulfo group, and their salts. Component (C) adsorbs to the surface of the molybdenum film to form a protective film, thereby reducing corrosion of the molybdenum site.

[0046] The amino group and its salts 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 formula (3) and the above formula (4), R 1 and R 2 Each of X independently represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group. - represents an anion.)

[0047] In the general formula (3) and the general formula (4), R 1 and R 2 Each independently represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group, and R 1 and R 2 may be bonded to form a ring structure.

[0048] R1 ~R 2 The hydrocarbon group represented by the formula (I) may be any of an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an araliphatic hydrocarbon group, or an alicyclic hydrocarbon group. The aliphatic moiety of the aliphatic hydrocarbon group and the araliphatic hydrocarbon group may be saturated or unsaturated, and may be linear or branched. Examples of these hydrocarbon groups include linear, branched, or cyclic alkyl groups, alkenyl groups, aralkyl groups, and aryl groups.

[0049] As the alkyl group, a lower alkyl group having 1 to 6 carbon atoms is usually preferred, and a lower alkyl group having 1 to 4 carbon atoms is more preferred. Examples of such alkyl groups include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a cyclopentyl group, and a cyclohexyl group.

[0050] The alkenyl group is generally preferably a lower alkenyl group having 1 to 6 carbon atoms, and more preferably a lower alkenyl group having 1 to 4 carbon atoms. Examples of such alkenyl groups include vinyl, n-propenyl, iso-propenyl, n-butenyl, iso-butenyl, sec-butenyl, and tert-butenyl groups.

[0051] The aralkyl group preferably has a carbon number of 7 to 12. Examples of such an aralkyl group include a benzyl group, a phenethyl group, a phenylpropyl group, a phenylbutyl group, a phenylhexyl group, a methylbenzyl group, a methylphenethyl group, and an ethylbenzyl group.

[0052] The aryl group preferably has a carbon number of 6 to 14. Examples of such an aryl group include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 2,3-chloro-2-methyl-2-propanol group, and a 2,3-chloro-2-methyl-2-propanol group. Examples thereof include a silyl group, a 2,4-xylyl group, a 2,5-xylyl group, a 2,6-xylyl group, a 3,5-xylyl group, a naphthyl group, and an anthryl group.

[0053] The aromatic rings of the aryl group and the aralkyl group may have, as a substituent, 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.

[0054] The carboxy group and its salts include functional groups represented by the following general formula (5). -COO - M + ·····(5) (M + represents a monovalent cation.)

[0055] In the above general formula (5), M + Examples of monovalent cations represented by the formula include, but are not limited to, H + , Li + , Na + , K. + , NH4 + Examples include:

[0056] The sulfo group and its salts include functional groups represented by the following general formula (6). -SO3 - M + ·····(6) (M + represents a monovalent cation.)

[0057] In the above general formula (6), M + Examples of monovalent cations represented by the formula include, but are not limited to, H + , Li + , Na + , K. + , NH4 + Examples include:

[0058] Component (C) is not particularly limited as long as it has a structure having 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, but it preferably has a structure represented by the following general formula (7) or (8): -N(R 3 COO - M + ) n (R 4 ) 2-n ·····(7) -N(R 3 SO3 - M + ) n (R 4 ) 2-n ·····(8) (In the above formula (7) and the above formula (8), R 3 represents a substituted or unsubstituted divalent hydrocarbon group. 4 represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group. + represents a monovalent cation. n represents an integer of 1 or 2.

[0059] In the general formula (7) and the general formula (8), R 3 Examples of the divalent hydrocarbon group represented by the formula (7) and the formula (8) include an alkanediyl group having 1 to 3 carbon atoms. 4 The hydrocarbon group represented by the formula (3) and the formula (4) includes R 1 ~R 2 In the above general formula (7) and the above general formula (8), M + Examples of monovalent cations represented by the formula include, but are not limited to, H + , Li + , Na + , K. + , NH4 + Examples include:

[0060] When component (C) has a structure represented by the above general formula (7) or (8), component (C) is effectively coordinated to the surface of the molybdenum film, thereby more effectively reducing corrosion of the molybdenum site.

[0061] Examples of component (C) include N-(phosphonomethyl)iminodiacetic acid, hydroxyethyliminodiacetic acid, nitrilotriacetic acid, N-(2-carboxyethyl)iminodiacetic acid, ethylenediaminetetraacetic acid, tetrasodium L-glutamate diacetate, glycine-N,N-bis(methylenephosphonic acid), 3,3',3''-nitrilotripropionic acid, octyliminodipropionate, lauryliminodipropionate, myristyliminodipropionate, stearyliminodipropionate, palmityliminodipropionate, glycol ether diaminetetraacetic acid, hydroxyethylethylenediaminetriacetic acid, 1,3-propane Examples of the component (C) include diamine-N,N,N',N'-tetraacetic acid, triethylenetetraaminehexaacetic acid, dihydroxyethylglycine, dodecylaminoethylaminoethylglycine, (S,S)-ethylenediaminedisuccinic acid trihydrate, iminodiacetic acid, trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid hydrate, lauramidopropyl hydroxysultaine, lauryl hydroxysulfobetaine, etc. These components (C) may be used singly or in combination of two or more.

[0062] The content of component (C) in the chemical mechanical polishing composition according to this embodiment is preferably 0.0005% by mass or more, more preferably 0.0008% by mass or more, and particularly preferably 0.001% by mass or more, when the total mass of the chemical mechanical polishing composition is taken as 100% by mass. The content of component (C) in the chemical mechanical polishing composition according to this embodiment is preferably 5% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, when the total mass of the chemical mechanical polishing composition is taken as 100% by mass. When the content of component (C) is within this range, corrosion of the molybdenum site may be effectively reduced.

[0063] 1.4.Other Ingredients In addition to the components described above, the chemical mechanical polishing composition of this embodiment may contain, as necessary, a liquid medium, a water-soluble polymer, a nitrogen-containing heterocyclic compound, a surfactant, an organic acid and its salt, an inorganic acid and its salt, a basic compound, etc.

[0064] <Liquid medium> The chemical mechanical polishing composition according to this embodiment contains a liquid medium. Examples of the liquid medium include water, a mixture of water and alcohol, and a mixture containing water and an organic solvent compatible with water. Among these, water, a mixture of water and alcohol is preferred, and water is more preferred. Pure water is preferably used as the water source. The liquid medium may be blended as the remainder of the aforementioned components.

[0065] <Water-soluble polymer> The chemical mechanical polishing composition according to this embodiment may contain a water-soluble polymer, which may adsorb to the surface of the polishing target surface to reduce polishing friction and reduce the occurrence of dishing on the polishing target surface.

[0066] Specific examples of water-soluble polymers include polycarboxylic acids, polystyrene sulfonic acids, polyacrylic acids, polymethacrylic acids, polyethers, polyacrylamides, polyvinyl alcohols, polyvinylpyrrolidone, polyethyleneimines, polyallylamine, hydroxyethyl cellulose, etc. These may be used alone or in combination of two or more.

[0067] The weight-average molecular weight (Mw) of the water-soluble polymer is preferably from 10,000 to 1.5 million, more preferably from 40,000 to 1.2 million. Here, the "weight-average molecular weight" refers to the weight-average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

[0068] When the chemical mechanical polishing composition according to this embodiment contains a water-soluble polymer, the content of the water-soluble polymer is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, based on the total mass of the chemical mechanical polishing composition being 100% by mass. The content of the water-soluble polymer is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, based on the total mass of the chemical mechanical polishing composition being 100% by mass.

[0069] <Nitrogen-containing heterocyclic compounds> Nitrogen-containing heterocyclic compounds are organic compounds containing at least one heterocyclic ring selected from five-membered heterocyclic rings and six-membered heterocyclic rings, each having at least one nitrogen atom. Specific examples of the heterocyclic ring include five-membered heterocyclic rings such as pyrrole, imidazole, and triazole structures; and six-membered heterocyclic rings such as pyridine, pyrimidine, pyridazine, and pyrazine structures. The heterocyclic ring may form a condensed ring. Specific examples include indole, isoindole, benzimidazole, benzotriazole, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, and acridine structures. Among heterocyclic compounds having such structures, heterocyclic compounds having a pyridine, quinoline, benzimidazole, or benzotriazole structure are preferred.

[0070] 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, carboxybenzotriazole, and derivatives having these skeletons. Among these, at least one selected from the group consisting of benzotriazole and triazole is preferred. These nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more.

[0071] <Surfactant> The surfactant is not particularly limited, and anionic surfactants, cationic surfactants, nonionic surfactants, etc. 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. Examples of nonionic surfactants include nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adducts, and acetylene alcohol; polyethylene glycol surfactants, etc. These surfactants may be used alone or in combination of two or more.

[0072] <Organic acids and their salts> The chemical mechanical polishing composition of this embodiment may contain at least one selected from the group consisting of organic acids and salts thereof (excluding component (C) and the water-soluble polymers having a carboxyl group or a sulfo group). The organic acids and salts thereof may have a synergistic effect with component (A) to improve the polishing rate for semiconductor substrates containing molybdenum films and silicon oxide films.

[0073] Organic acids and their salts are preferably compounds having a carboxy group or 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, 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; and salts thereof. These compounds may be used alone or in combination of two or more.

[0074] When the chemical mechanical polishing composition according to this embodiment contains an organic acid (salt), the organic acid (salt) The content of the organic acid (salt) is preferably 5% by mass or less, more preferably 1% by mass or less, based on 100% by mass of the total mass of the chemical mechanical polishing composition.

[0075] <Inorganic acids and their 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 base added separately to the chemical mechanical polishing composition.

[0076] <Basic compounds> Examples of basic compounds include organic bases and inorganic bases. Preferred organic bases include amines, such as triethylamine, monoethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzylamine, methylamine, ethylenediamine, diglycolamine, and isopropylamine. Examples of inorganic bases include ammonia, potassium hydroxide, and sodium hydroxide. Among these basic compounds, ammonia and potassium hydroxide are preferred. These basic compounds may be used alone or in combination of two or more.

[0077] <Hydrogen peroxide> The chemical mechanical polishing composition according to this embodiment may contain hydrogen peroxide, but preferably does not contain hydrogen peroxide, because hydrogen peroxide excessively oxidizes molybdenum and promotes excessive corrosion (etching) of the molybdenum moiety, often resulting in an unsatisfactory polished surface.

[0078] 1.5.pH The pH of the chemical mechanical polishing composition of 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 of this embodiment is preferably 6 or lower, more preferably 5 or lower, and particularly preferably 4 or lower. When the pH of the chemical mechanical polishing composition of this embodiment is within the above range, the surface of the molybdenum film is effectively oxidized to easily create a brittle modified layer, which tends to improve the removal rate of the molybdenum film.

[0079] The pH of the chemical mechanical polishing composition can be adjusted by adding, for example, the aforementioned component (C), organic acids (salts), inorganic acids (salts), basic compounds, etc., and one or more of these can be used.

[0080] In the present invention, pH refers to hydrogen ion exponent, and its value can be measured using a commercially available pH meter (for example, a tabletop pH meter manufactured by Horiba, Ltd.).

[0081] 1.6. Method for preparing chemical mechanical polishing composition The chemical mechanical polishing composition according to this embodiment can be prepared by dissolving or dispersing the aforementioned components in a liquid medium such as water. The dissolving or dispersing method is not particularly limited, and any method may be used as long as it can dissolve or disperse the components uniformly. Furthermore, the mixing order and mixing method of the aforementioned components are not particularly limited.

[0082] The chemical mechanical polishing composition can also be prepared as a concentrated stock solution, which can be diluted with a liquid medium such as water before use.

[0083] 2. Polishing method A polishing method according to one embodiment of the present invention includes polishing a semiconductor substrate using the aforementioned chemical mechanical polishing composition. The chemical mechanical polishing composition can chemically polish a semiconductor substrate containing a molybdenum film at a stable polishing rate while suppressing corrosion of the molybdenum film. Therefore, the semiconductor substrate to be processed preferably has a portion composed of at least one material selected from the group consisting of molybdenum and molybdenum alloys. The polishing method according to this embodiment is described in detail below with reference to FIGS. 1 to 4.

[0084] 2.1. Object to be treated FIG. 1 shows an example of a workpiece 100 to which the chemical mechanical polishing method according to this embodiment is applied.

[0085] (1) First, a base substrate 10 is prepared as shown in FIG. 1. The base 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 base substrate 10. Next, a silicon oxide film 12, which is an insulating film, is formed on the base substrate 10 using a CVD method or a thermal oxidation method.

[0086] (2) Next, the silicon oxide film 12 is patterned. Using this as a mask, the silicon oxide film 12 is subjected to photolithography to form via holes 14.

[0087] (3) Next, a barrier metal film 16 is formed by sputtering on the surface of the silicon oxide film 12 and the inner wall surface of the via hole 14. Because the electrical contact between molybdenum and silicon is not very good, the barrier metal film ensures good electrical contact. Examples of the barrier metal film 16 include titanium and / or titanium nitride.

[0088] (4) Next, a molybdenum film 18 is formed by applying the CVD method.

[0089] Through the above steps, the object to be processed 100 is formed.

[0090] 2.2.Chemical mechanical polishing method 2.2.1. First polishing process 2, the first polishing step is a step in which the barrier metal film 16 and the molybdenum film 18 are polished using the chemical mechanical polishing composition described above until the silicon oxide film 12 is exposed. The chemical mechanical polishing composition described above has an excellent polishing effect on not only the molybdenum film but also the barrier metal film, so the barrier metal film 16 and the molybdenum film 18 can be polished and removed in the same processing step.

[0091] 2.2.2. Second polishing process 3, the second polishing step is a step in which the barrier metal film 16, the molybdenum film 18, and the silicon oxide film 12 are simultaneously polished using the aforementioned chemical mechanical polishing composition. Because the aforementioned chemical mechanical polishing composition has non-selective polishing properties for the molybdenum film and the silicon oxide film, the second polishing step can provide a finished surface with extremely excellent flatness.

[0092] The chemical mechanical polishing composition used in the second polishing step may be prepared by appropriately changing the concentration of component (B) contained in the chemical mechanical polishing composition used in the first polishing step within the aforementioned composition range. By adjusting the concentration of 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. The polishing rate of a silicon oxide film relative to the polishing rate of a molybdenum film can be adjusted to 1 or more by adjusting the zeta potential or degree of association of component (A) in the chemical mechanical polishing composition.

[0093] 2.2.3.Chemical mechanical polishing equipment 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. The polishing is performed by supplying a slurry 44 from a slurry supply nozzle 42 and bringing a carrier head 52 holding a semiconductor substrate 50 into contact with a turntable 48 to which a polishing cloth 46 is attached while the turntable 48 is rotating. Note that FIG. 4 also shows a water supply nozzle 54 and a dresser 56.

[0094] The polishing pressure of the carrier head 52 can be selected within a range of 10 to 980 hPa, and preferably 30 to 490 hPa. The rotation speed of the turntable 48 and the carrier head 52 can be appropriately selected within a range of 10 to 400 rpm, and preferably 30 to 150 rpm. The flow rate of the slurry 44 supplied from the slurry supply nozzle 42 can be selected within a range of 10 to 1,000 mL / min, and preferably 50 to 400 mL / min.

[0095] 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; and models "Mirra" and "Reflexion" manufactured by Applied Materials, Inc.

[0096] 3. Working Example The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are by mass unless otherwise specified.

[0097] 3.1. Preparation of silica particle aqueous dispersion 3.1.1. Preparation of Aqueous Dispersion A According to Example 3 described in WO 2008 / 123373, an aqueous dispersion A containing 15.5% by mass of silica particles and having a pH of 7.6 was obtained. Aqueous Dispersion A was measured by dynamic light scattering (manufactured by Malvern, model "Zetasizer Ultra"), and the average secondary particle diameter of the silica particles contained in Aqueous Dispersion A was found to be 17.3 nm in terms of volume. In addition, aqueous dispersion A was photographed at a magnification of 30,000 times using a transmission electron microscope (TEM) (Hitachi High-Technologies Corporation, model "H-7650"), and for 50 images of observed silica particles, the longest distance between the ends of the particle images was measured, and the average of these values ​​was calculated as the average primary particle size. The average primary particle size of the silica particles contained in aqueous dispersion A calculated in this way was 15.8 nm. The degree of association was calculated using the average primary particle size and average secondary particle size calculated by the above-mentioned method according to the following calculation formula, and the degree of association of the silica particles contained in aqueous dispersion A was found to be 1.1. Degree of association = (average secondary particle diameter) / (average primary particle diameter) Hereinafter, the average primary particle size, average secondary particle size and degree of association of the silica particles contained in each aqueous dispersion were measured and calculated in the same manner.

[0098] 3.1.2. Preparation of Aqueous Dispersion B 2520 g of aqueous dispersion A (15.5% colloidal silica dispersion) was heated to 60°C. Then, 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 to obtain aqueous dispersion B containing silica particles surface-modified with carboxy groups and having an average secondary particle diameter of 17.3 nm.

[0099] 3.1.3. Preparation of Aqueous Dispersion C 25% aqueous ammonia (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 2520 g of aqueous dispersion A (15.5% colloidal silica dispersion) and the pH was adjusted to 9. 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 then added dropwise, and the mixture was stirred at 60°C for 2 hours. 50 g of hydrogen peroxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was then added, and the mixture was refluxed under normal pressure for 8 hours to obtain aqueous dispersion C containing sulfo-modified silica particles with an average secondary particle diameter of 17.3 nm.

[0100] 3.1.4. Preparation of Aqueous Dispersion D PL-1 (12% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) was used as it was as aqueous dispersion D. When measured by the above method, the average secondary particle diameter of the silica particles contained in aqueous dispersion D was 30.1 nm.

[0101] 3.1.5. Preparation of Aqueous Dispersion E 25% aqueous ammonia (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 3250 g of PL-1 (12% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) and the pH was adjusted to 9. 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 then added dropwise and stirred at 60°C for 2 hours. 50 g of hydrogen peroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added and the mixture was refluxed under normal pressure for 8 hours to obtain aqueous dispersion E containing sulfo-modified silica particles with an average secondary particle diameter of 30.1 nm.

[0102] 3.1.6. Preparation of Water Dispersion F 1950 g of PL-3 (19.5% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) was heated to 60° C. Then, 15.5 g of (3-triethoxysilyl)propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60° C. for an additional 4 hours to obtain aqueous dispersion F containing silica particles surface-modified with carboxy groups and having an average secondary particle diameter of 58.2 nm.

[0103] 3.1.7. Preparation of Aqueous Dispersion G 25% aqueous ammonia (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 2000 g of PL-3 (19.5% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) and the pH was adjusted to 9. 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 then added dropwise and stirred at 60°C for 2 hours. 50 g of hydrogen peroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added and the mixture was refluxed under normal pressure for 8 hours to obtain aqueous dispersion G containing sulfo-modified silica particles with an average secondary particle diameter of 58.2 nm.

[0104] 3.1.8. Preparation of Aqueous Dispersion H 25% aqueous ammonia (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 1950 g of PL-2L (20% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) and the pH was adjusted to 9. 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 then added dropwise, and the mixture was stirred at 60°C for 2 hours. 50 g of hydrogen peroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added, and the mixture was refluxed under normal pressure for 8 hours to obtain aqueous dispersion H containing sulfo-modified silica particles with an average secondary particle diameter of 22.5 nm.

[0105] 3.1.9. Preparation of Aqueous Dispersion I 1950 g of PL-2L (20% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) was heated to 60°C. Then, 15.5 g of (3-triethoxysilyl)propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60°C for an additional 4 hours to obtain aqueous dispersion I containing silica particles surface-modified with carboxy groups and having an average secondary particle diameter of 22.5 nm.

[0106] 3.1.10. Preparation of Water Dispersion J 25% aqueous ammonia (Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 6510 g of PL-06L (6% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) and the pH was adjusted to 9. 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 then added dropwise, and the mixture was stirred at 60°C for 2 hours. 50 g of hydrogen peroxide (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added, and the mixture was refluxed under normal pressure for 8 hours to obtain aqueous dispersion J containing sulfo-modified silica particles with an average secondary particle diameter of 7.4 nm.

[0107] 3.1.11. Preparation of aqueous dispersion K 6510 g of PL-06L (6% colloidal silica dispersion, manufactured by Fuso Chemical Co., Ltd.) was heated to 60°C. Then, 15.5 g of (3-triethoxysilyl)propylsuccinic anhydride (manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 60°C for an additional 4 hours to obtain aqueous dispersion K containing silica particles surface-modified with carboxy groups and having an average secondary particle diameter of 7.4 nm.

[0108] 3.1.12. Preparation of Water Dispersion L A mixture of 70 g of methanol and 11.3 g of 3-aminopropyltriethoxysilane (Tokyo Chemical Industry Co., Ltd.) was added dropwise to 2520 g of aqueous dispersion A (15.5% colloidal silica dispersion), and the mixture was refluxed under normal pressure for 2 hours. Subsequently, pure water was added dropwise while maintaining the volume constant. The addition of pure water was stopped when the column top temperature reached 100°C, yielding aqueous dispersion L containing silica particles surface-modified with amino groups and having an average secondary particle diameter of 17.3 nm.

[0109] 3.2. Preparation of component (C) 3.2.1. Preparation of Octyliminodipropionate 2.5 g (19.5 mmol) of octylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) as an alkylamine and 5.7 g (52.9 mmol) of 3-chloropropionic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) were added to a mixed solution of 5.0 mL of water and 32 mL of ethanol (manufactured by Kanto Chemical Co., Ltd.), and the mixture was refluxed and stirred for 6 hours. During this reflux and stirring, 7.8 mL of a potassium hydroxide aqueous solution (5.0 mol / L) prepared from potassium hydroxide (manufactured by Kanto Chemical Co., Ltd.) was added to adjust the pH. The solution was then cooled to 4°C, and a precipitate was formed. The formed precipitate was washed with ethanol, filtered, and dried under reduced pressure to recover the solid, yielding octyliminodipropionate.

[0110] 3.2.2. Preparation of Lauryl Imino Dipropionate Lauryliminodipropionate was obtained in the same manner as in "3.2.1. Preparation of octyliminodipropionate" above, except that 3.6 g (19.5 mmol) of laurylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the alkylamine.

[0111] 3.2.3. Preparation of myristyl iminodipropionate Myristyliminodipropionate was obtained in the same manner as in "3.2.1. Preparation of octyliminodipropionate" above, except that 4.2 g (19.5 mmol) of myristylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the alkylamine.

[0112] 3.2.4. Preparation of Palmityliminodipropionate Palmityliminodipropionate was obtained in the same manner as in "3.2.1. Preparation of octyliminodipropionate" above, except that 4.7 g (19.5 mmol) of palmitylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the alkylamine.

[0113] 3.2.5. Preparation of stearyl iminodipropionate Stearyliminodipropionate was obtained in the same manner as in "3.2.1. Preparation of octyliminodipropionate" above, except that 5.3 g (19.5 mmol) of stearylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the alkylamine.

[0114] 3.3. Preparation of Chemical Mechanical Polishing Composition The components were mixed to obtain the compositions shown in Tables 1 to 3, and pH adjusters such as potassium hydroxide aqueous solution (manufactured by Kanto Chemical Co., Inc., trade name "48% potassium hydroxide aqueous solution"), ammonia water (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "ammonia water"), and maleic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "maleic acid") were added as needed to obtain the pHs shown in Tables 1 to 3. Pure water was then added so that the total amount of all components was 100% by mass, thereby preparing chemical mechanical polishing compositions for each Example and Comparative Example. Each chemical mechanical polishing composition obtained in this manner was measured using a zeta potential measurement device (Dispersion The zeta potential of the abrasive grains was measured using a DT300 (manufactured by TECHNOLOGY, Inc.) and the results are shown in Tables 1 to 3.

[0115] 3.4.Evaluation Method 3.4.1. Evaluation of Molybdenum and Silicon Oxide Film Removal Rates 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 subjected to a chemical mechanical polishing test under the conditions below, followed by brush scrubbing under the conditions below. (polishing conditions) Polishing equipment: Applied Materials, model "Reflexion-LK" Polishing pad: Fujibo Co., Ltd., "Porous polyurethane pad; H800-type1(3-1S)775" ·Chemical mechanical polishing composition supply rate: 300mL / min Platen rotation speed: 100 rpm Head rotation speed: 90 rpm Head pressure: 2 psi ·Polishing time: 60 seconds Polishing rate (nm / min) = (film thickness before polishing - film thickness after polishing) / polishing time (Brush scrub cleaning conditions) Treatment 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

[0116] The thickness of the molybdenum film was calculated by measuring the resistance using a DC four-probe method with a resistivity measuring device (KLA-Tencor, model RS-100) and using the sheet resistance value and the volume resistivity of molybdenum according to the following formula. Molybdenum film thickness (nm) = [volume resistivity of molybdenum film (Ω·m) ÷ sheet resistance value (Ω / sq)] × 10 9 The thickness of the silicon oxide film was measured using an optical film thickness measuring device (KLA Tencor Corporation, model "ASET F5x").

[0117] The evaluation criteria for the polishing rate of the molybdenum film are as follows: The evaluation results of the polishing rate of the molybdenum film are shown in Tables 1 to 3. (Evaluation criteria) · AA: When the polishing rate was 2.5 nm / min or more and less than 30 nm / min, it was judged to be very good since it was an appropriate polishing rate. A: When the polishing rate is 30 nm / min or more and less than 40 nm / min, the polishing rate is high and requires careful control during mass production, but it is practical and therefore judged to be good. B: When the removal rate was less than 2.5 nm / min, the removal rate was judged to be poor because it was too slow and difficult to use. Alternatively, when the removal rate was 40 nm / min or more, the removal rate was judged to be poor because it was too high and could not be controlled in mass production and therefore difficult to use.

[0118] Further, the polishing rate ratio was calculated according to the following formula using the polishing rate for the molybdenum film and the polishing rate for the silicon oxide film calculated above. Polishing rate ratio = Polishing rate of silicon oxide film (nm / min) / Polishing rate of molybdenum film (nm / min) (Evaluation criteria) · AA: When the polishing rate ratio is 1 or more, it is judged to be very good because excessive polishing of the molybdenum film relative to the silicon oxide film can be sufficiently suppressed. A: When the polishing rate ratio is 0.5 or more but less than 1, the polishing rate of the molybdenum film relative to the silicon oxide film is large and requires careful control during mass production, but it is practical and therefore judged to be good. B: When the polishing rate ratio is less than 0.5, the molybdenum film is excessively polished relative to the silicon oxide film, making it difficult to use, and therefore it is judged to be defective.

[0119] 3.4.2. Evaluation of the etching rate of molybdenum films The chemical mechanical polishing composition prepared above was heated to 60°C, and a wafer piece with a 200nm molybdenum film cut to 30mm x 10mm was immersed for 5 minutes. The wafer piece was then removed and washed with running water, and the thickness of the molybdenum film was measured using the same method as in "3.4.1. Evaluation of the polishing rate of molybdenum film and silicon oxide film" above. The etching rate was calculated from the change in the thickness of the molybdenum film before and after immersion using the following formula. Etching rate of molybdenum film (nm / min) = (thickness of molybdenum film before etching (nm) - thickness of molybdenum film after etching (nm)) / etching time (min)

[0120] The evaluation criteria for the etching rate of the molybdenum film are as follows: The evaluation results for the etching rate of the molybdenum film are shown in Tables 1 to 3. (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 is 0.1 nm / min or more, the etching rate is too high to be practically used, and the result is judged to be poor.

[0121] 3.4.3. Evaluation of defects in silicon oxide films The number of defects on the entire surface of the polished silicon oxide film wafer obtained in the above "3.4.1. Evaluation of the polishing rate of molybdenum film and silicon oxide film" was counted using a defect inspection device (KLA Tencor, model "Surfscan SP2").

[0122] The evaluation criteria for the number of defects are as follows: The evaluation results for the number of defects in the silicon oxide film are shown in Tables 1 to 3. (Evaluation criteria) A: If the number of defects in the silicon oxide film is less than 100, it can be used for practical purposes. Therefore, it was judged to be good. B: When the number of defects in the silicon oxide film was 100 or more, the film was judged to be defective because it could not be used in practice.

[0123] 3.5.Evaluation Results Tables 1 to 3 show the compositions of the chemical mechanical polishing compositions used in each of the Examples and Comparative Examples, as well as the evaluation results.

[0124] [Table 1]

[0125] [Table 2]

[0126] [Table 3]

[0127] 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" <Ingredient (B)> Ethylenediaminetetraacetic acid ferric ammonium dihydrate: Chelest Co., Ltd., product name "Chilest FN" Iron citrate trihydrate: Manufactured by Fuso Chemical Co., Ltd., product name "Fuji Iron Citrate" Iron acetylacetonate: Kishida Chemical Co., Ltd., product name "iron acetylacetonate (III)" Diethylenetriaminepentaacetic acid iron diammonium salt: Chelest Co., Ltd., product name "Chilest FNZ-50" 1,3-Diaminopropanetetraacetate ferric ammonium monohydrate: Cherest Co., Ltd., trade name "Chirest PD-FN" <Ingredient (C)> Octyliminodipropionate: Octyliminodipropionate prepared in the above section "3.2. Preparation of component (C)" Lauryliminodipropionate: Lauryliminodipropionate prepared in the above section "3.2. Preparation of component (C)" Myristyl imino dipropionate: Myristyl imino dipropionate prepared in the above section "3.2. Preparation of component (C)" Palmityliminodipropionate: Palmityliminodipropionate prepared in the above section "3.2. Preparation of component (C)" Stearyl iminodipropionate: Stearyl iminodipropionate prepared in the above section "3.2. Preparation of component (C)" Dodecylaminoethylaminoethylglycine: Sanyo Chemical Industries, Ltd., product name "Revon S" Lauramidopropyl hydroxysultaine: Kawaken Fine Chemicals Co., Ltd., product name "Softazoline LSB-R" Lauryl hydroxysulfobetaine: Kao Corporation, product name "Amphitol 20HD" <Other additives> Hydrogen peroxide: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product 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., product name "Ammonium peroxodisulfate" Iron(II) sulfate heptahydrate: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "Iron(II) sulfate heptahydrate" Ethylenediaminetetraacetic acid diammonium salt: Chelest Corporation, trade name "Chilest 2N-40"

[0128] The chemical mechanical polishing compositions of Examples 1 to 24, which contain a combination of component (A) and component (B) having specific functional groups, can oxidize the molybdenum film to promote polishing, while preventing excessive reactions between molybdenum and anionic species and reducing the occurrence of corrosion of the molybdenum film. Furthermore, the use of component (A) having specific functional groups increases the repulsive force between abrasive particles in the chemical mechanical polishing composition, suppressing agglomeration of the abrasive particles. This allows both molybdenum and silicon oxide films to be polished at a stable polishing rate while reducing the occurrence of defects in the silicon oxide film.

[0129] In contrast, the chemical mechanical polishing compositions of Comparative Examples 1 to 2 and 7, which contain abrasive grains without specific functional groups, are prone to defects in the silicon oxide film, making them difficult to put to practical use.Furthermore, the chemical mechanical polishing compositions of Comparative Examples 3 to 6, which do not contain component (B), exhibit excessively low removal rates of the molybdenum film, making them difficult to put to practical use.

[0130] 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 those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0131] 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

1. The abrasive grains (A) and a chelate compound (B) of iron (III) ions (excluding those derived from iron (III) nitrate) are contained, A chemical mechanical polishing composition for a substrate containing a molybdenum film and a silicon oxide film, wherein the abrasive grains (A) have at least one functional group selected from the group consisting of a functional group represented by the following general formula (1) and a functional group represented by the following general formula (2): -SO ３ － M ＋ ・・・・・(1) -COO － M ＋ ・・・・・(2) (In the above formulas (1) and (2), M ＋ represents a monovalent cation.)

2. A chemical mechanical polishing composition for substrates containing a molybdenum film and a silicon oxide film as described in claim 1, further containing a compound (C) having at least one functional group selected from the group consisting of an amino group and its salts, and at least one functional group selected from the group consisting of a carboxy group, a sulfo group, and their salts.

3. A chemical mechanical polishing composition for substrates containing a molybdenum film and a silicon oxide film as described in claim 1 or claim 2, wherein the average secondary particle diameter of the abrasive grains (A) in the chemical mechanical polishing composition is 5 nm or more and 100 nm or less.

4. A chemical mechanical polishing composition for substrates comprising a molybdenum film and a silicon oxide film as described in any one of claims 1 to 3, 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.

5. A chemical mechanical polishing composition for substrates comprising a molybdenum film and a silicon oxide film as described in any one of claims 1 to 4, wherein the zeta potential of the abrasive grains (A) in the chemical mechanical polishing composition is less than 0 mV.

6. 6. A chemical mechanical polishing composition for substrates, comprising the molybdenum film and silicon oxide film according to claim 1, having a pH of 1 or more and 6 or less.

7. A polishing method comprising the step of polishing a semiconductor substrate including a molybdenum film and a silicon oxide film using the chemical mechanical polishing composition of claim 1 .

8. 8. The polishing method according to claim 7, wherein the semiconductor substrate comprises a portion made of at least one material selected from the group consisting of molybdenum and molybdenum alloys.

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