WO2024181261A1

WO2024181261A1 - Chemical-mechanical polishing composition and polishing method

Info

Publication number: WO2024181261A1
Application number: PCT/JP2024/006201
Authority: WO
Inventors: 康孝亀井
Original assignee: Jsr株式会社
Priority date: 2023-03-01
Filing date: 2024-02-21
Publication date: 2024-09-06

Abstract

The present invention provides a chemical-mechanical polishing composition with which it is possible to increase the polishing rate of a tungsten film and reduce the occurrence of corrosion and defects on the tungsten surface, and also provides a polishing method.　This chemical-mechanical polishing composition contains (A) abrasive grains, (B) a heterocyclic compound, and (C) a liquid medium, and MA/MB=50 to 10,000, where MA (parts by mass) is the (A) component content, and MB (parts by mass) is the (B) component content.

Description

Chemical mechanical polishing composition and polishing method

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

As semiconductor manufacturing technology improves, 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 semiconductors in semiconductor elements is becoming increasingly strict, and chemical mechanical polishing (CMP) has become an essential technology in the manufacturing process of semiconductor elements.

For example, tungsten, which has excellent embedding properties, is used for contact holes that electrically connect wiring in the vertical and vertical directions. Compositions that contain an oxidizing agent such as hydrogen peroxide, an iron catalyst such as iron nitrate, and abrasive grains such as silica have been proposed as chemical mechanical polishing compositions used to polish away excess tungsten film on insulating films (see, for example, Patent Documents 1 to 3).

Special Publication No. 2005-518091 JP 2007-19093 A Special Publication No. 2008-503875

Chemical mechanical polishing compositions used to polish tungsten films require the tungsten surface to be oxidized to create an oxide film, and so are usually acidic, with a pH of about 2 to 5. As a result, corrosion and defects are likely to occur on the tungsten surface after CMP, and there is a demand for chemical mechanical polishing compositions that can reduce corrosion and the occurrence of defects on the tungsten surface as much as possible.

Some aspects of the present invention provide a chemical mechanical polishing composition and a polishing method that can polish tungsten films at a high rate and reduce the occurrence of corrosion and defects on the tungsten surface.

One aspect of the chemical mechanical polishing composition of the present invention is
(A) abrasive grains;
(B) a heterocyclic compound;
(C) a liquid medium;
A chemical mechanical polishing composition comprising:
When the content of the component (A) is MA [parts by mass] and the content of the component (B) is MB [parts by mass], MA/MB=50 to 10,000.

In one embodiment of the chemical mechanical polishing composition,
The component (B) may be a nitrogen-containing heterocyclic compound.

In any one of the embodiments of the chemical mechanical polishing composition,
The nitrogen-containing heterocyclic compound may have an isothiazolinone structure or a thiazole structure.

In any one of the embodiments of the chemical mechanical polishing composition,
The pH may be 2 or more and 7 or less.

In any one of the embodiments of the chemical mechanical polishing composition,
The component (A) may have a functional group represented by the following general formula (1).
-SO ₃ ^- M ⁺ ...(1)
(M ⁺ represents a monovalent cation.)

In any one of the embodiments of the chemical mechanical polishing composition,
The component (A) may have a functional group represented by the following general formula (2).
-COO ^- M ⁺ ...(2)
(M ⁺ represents a monovalent cation.)

In any one of the embodiments of the chemical mechanical polishing composition,
The component (A) may have a functional group represented by the following general formula (3) or the following general formula (4).
-NR ¹ R ² ...(3)
-N ⁺ R ¹ R ² R ³ M ^-... (4)
(In the above formulas (3) and (4), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group. ^{M −} represents an anion.)

In any one of the embodiments of the chemical mechanical polishing composition,
The amount of the component (A) may be 1 part by mass or more and 20 parts by mass or less based on 100 parts by mass of the chemical mechanical polishing composition.

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

The chemical mechanical polishing composition of the present invention can increase the polishing rate of the tungsten film during CMP, which polishes a workpiece provided with a wiring layer containing tungsten, and can reduce corrosion and defects on the tungsten surface.

FIG. 1 is a cross-sectional view that shows a schematic diagram of a target object suitable for use in the polishing method according to the present embodiment. FIG. 2 is a cross-sectional view that illustrates the polishing method according to this embodiment. FIG. 3 is a perspective view showing a schematic diagram of a chemical mechanical polishing apparatus. FIG. 4 is a cross-sectional view that typically shows a patterned wafer used in the examples.

Below, a preferred embodiment of the present invention will be described in detail. Note that the present invention is not limited to the following embodiment, and includes various modifications that are implemented within the scope that does not change the gist of the present invention.

In this specification, "wiring material" refers to conductive metal materials such as aluminum, copper, cobalt, titanium, ruthenium, and tungsten. "Insulating film material" refers to materials such as silicon dioxide, silicon nitride, and amorphous silicon. "Barrier metal material" refers to materials such as tantalum nitride and titanium nitride that are used in layers with wiring materials to improve the reliability of the wiring.

In this specification, a numerical range described using "X to Y" means that the numerical range includes the numerical value X as the lower limit and the numerical value Y as the upper limit.

1. Chemical Mechanical Polishing Composition A chemical mechanical polishing composition according to one embodiment of the present invention contains (A) abrasive grains (also referred to herein as "component (A)"), (B) a heterocyclic compound (also referred to herein as "component (B)"), and (C) a liquid medium (also referred to herein as "component (C)"), in which, when the content of component (A) is MA [parts by mass] and the content of component (B) is MB [parts by mass], MA/MB = 50 to 10,000. Components that may be contained in the chemical mechanical polishing composition according to this embodiment are described in detail below.

1.1. Abrasive grains (A) The chemical mechanical polishing composition according to this embodiment contains abrasive grains (A). Component (A) is preferably an abrasive grain containing silica as a main component, and more preferably colloidal silica. Component (A) can be produced by applying the method described in, for example, JP-A-2007-153732 or JP-A-2013-121631.

When component (A) is an abrasive grain containing silica as the main component, component (A) may further contain other components in addition to silica. Examples of other components include aluminum compounds, silicon compounds, etc. By further containing an aluminum compound or silicon compound in component (A), the surface hardness of component (A) can be reduced, which may further reduce the occurrence of polishing scratches and dishing on the polished surface.

Examples of aluminum compounds include aluminum hydroxide, aluminum oxide (alumina), aluminum chloride, aluminum nitride, aluminum acetate, aluminum phosphate, aluminum sulfate, sodium aluminate, potassium aluminate, etc. On the other hand, examples of silicon compounds include silicon nitride, silicon carbide, silicates, silicone, silicone resins, etc.

It is preferable that the absolute value of the zeta potential of component (A) in the chemical mechanical polishing composition is 10 mV or more. When the absolute value of the zeta potential of component (A) in the chemical mechanical polishing composition is 10 mV or more, the dispersion stability of component (A) is improved due to electrostatic repulsion, and it may be possible to polish the tungsten film at high speed while reducing the occurrence of defects on the tungsten surface. When the absolute value of the zeta potential in the chemical mechanical polishing composition is less than 10 mV, the absolute value of the zeta potential in the chemical mechanical polishing composition can be increased by modifying at least a portion of the surface of the abrasive grain with a functional group.

The average particle size of component (A) is preferably 10 nm or more and 300 nm or less, and more preferably 20 nm or more and 200 nm or less. When the average particle size of component (A) is within the above range, a sufficient polishing rate for the tungsten film can be obtained, and a chemical mechanical polishing composition with excellent stability that does not cause particle settling or separation can be obtained. The average particle size of component (A) can be calculated from the measured value by measuring the specific surface area by the BET method using, for example, an automatic dynamic adsorption surface area measuring device (Micromeritics FlowSorb II 2300, manufactured by Micromeritics).

The (A) component may have multiple protrusions on its surface. The protrusions referred to here have a height and width sufficiently smaller than the particle diameter of the abrasive grain. When the (A) component has multiple protrusions on its surface, the number of protrusions is preferably 3 or more on average per abrasive grain, and more preferably 5 or more. In other words, the (A) component having multiple protrusions on its surface can be said to be an abrasive grain having a unique shape, such as a confetti-like shape. The unique shape of the (A) component increases the surface area, and enhances the reactivity with a compound having a functional group, which will be described later. This increases the absolute value of the zeta potential of the (A) component in the chemical mechanical polishing composition, and improves the dispersion stability. As a result, it may be possible to polish a tungsten film at high speed while reducing the occurrence of defects on the tungsten surface.

The (A) component is preferably an abrasive grain having at least a portion of its surface modified with a functional group. In the pH range of 2 to 7, the abrasive grain having at least a portion of its surface modified with a functional group has a larger absolute value of zeta potential and a stronger electrostatic repulsion between the abrasive grains than abrasive grains that are not surface-modified with a functional group. As a result, the dispersion stability of the abrasive grains in the chemical mechanical polishing composition is improved, and it may be possible to polish the tungsten film at high speed while reducing the occurrence of defects on the tungsten surface.

Specific aspects of component (A) are described in detail below.

1.1.1. First embodiment The first embodiment of the component (A) is an abrasive grain having a functional group represented by the following general formula (1) and having a plurality of protrusions on the surface.
-SO ₃ ^- M ⁺ ...(1)
(M ⁺ represents a monovalent cation.)

In the above formula (1), the monovalent cation represented by M ⁺ includes, but is not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . That is, the functional group represented by the above general formula (1) can be rephrased as "at least one functional group selected from the group consisting of sulfo groups and their salts". Here, "salt of sulfo group" refers to a functional group in which the hydrogen ion contained in the sulfo group (-SO ₃ H) is replaced with a monovalent cation such as Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . The component (A) according to the first embodiment is an abrasive grain having a functional group represented by the above general formula (1) fixed to its surface via a covalent bond, and does not include an abrasive grain having a compound having a functional group represented by the above general formula (1) physically or ionically adsorbed to its surface.

The component (A) according to the first embodiment can be manufactured by applying the method described in JP-A-2010-269985, for example. Specifically, first, silica having multiple protrusions on its surface is prepared by applying the method described in JP-A-2007-153732 or JP-A-2013-121631. Next, the silica having multiple protrusions on its surface and the mercapto group-containing silane coupling agent are thoroughly stirred in an acidic medium, so that the mercapto group-containing silane coupling agent is covalently bonded to the surface of the silica having multiple protrusions on its surface. Examples of the mercapto group-containing silane coupling agent include 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. Next, an appropriate amount of hydrogen peroxide is further added and the mixture is left to stand for a sufficient period, whereby an abrasive grain having a functional group represented by the above general formula (1) and having multiple protrusions on its surface can be obtained.

When the chemical mechanical polishing composition according to this embodiment contains the component (A) according to the first aspect, the content of the component (A) according to the first aspect is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 4 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the component (A) according to the first aspect is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and particularly preferably 16 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. When the content of the component (A) according to the first aspect is within the above range, polishing scratches may be suppressed.

1.1.2. Second embodiment A second embodiment of the component (A) is an abrasive grain having a functional group represented by the following general formula (2) and having a plurality of protrusions on the surface.
-COO ^- M ⁺ ...(2)
(M ⁺ represents a monovalent cation.)

In the above formula (2), the monovalent cation represented by M ⁺ includes, but is not limited to, H ⁺ , Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . That is, the functional group represented by the above general formula (2) can be rephrased as "at least one functional group selected from the group consisting of carboxy groups and their salts". Here, "carboxy salt" refers to a functional group in which the hydrogen ion contained in the carboxy group (-COOH) is replaced with a monovalent cation such as Li ⁺ , Na ⁺ , K ⁺ , and NH ₄ ⁺ . The component (A) according to the second embodiment is an abrasive grain having a functional group represented by the above general formula (2) fixed to its surface via a covalent bond, and does not include an abrasive grain having a compound having a functional group represented by the above general formula (2) physically or ionically adsorbed to its surface.

The component (A) according to the second embodiment can be manufactured by applying the method described in JP-A-2010-105896, for example. Specifically, first, silica having multiple protrusions on its surface is prepared by applying the method described in JP-A-2007-153732 or JP-A-2013-121631. Next, the silica having multiple protrusions on its surface and a carboxylic anhydride-containing silane coupling agent are thoroughly stirred in a basic medium to covalently bond the carboxylic anhydride-silane coupling agent to the surface of the abrasive grain having multiple protrusions on its surface, thereby obtaining an abrasive grain having a functional group represented by the above general formula (2) and having multiple protrusions on its surface. Here, an example of the carboxylic anhydride-containing silane coupling agent is 3-(triethoxysilyl)propylsuccinic anhydride.

When the chemical mechanical polishing composition according to this embodiment contains the component (A) according to the second aspect, the content of the component (A) according to the second aspect is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 4 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the component (A) according to the second aspect is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and particularly preferably 16 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. When the content of the component (A) according to the second aspect is within the above range, polishing scratches may be suppressed.

1.1.3. Third Aspect A third aspect of the component (A) is an abrasive grain having a functional group represented by the following general formula (3) or the following general formula (4) and having a plurality of protrusions on the surface.
-NR ¹ R ² ...(3)
-N ⁺ R ¹ R ² R ³ M ^- (4)
(In the above formula (3) and formula (4), R ¹ , R ² and R ³ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group. M ⁻ represents an anion.)

The functional group represented by the general formula (3) above represents an amino group, and the functional group represented by the general formula (4) above represents a salt of an amino group. Therefore, the functional group represented by the general formula (3) above and the functional group represented by the general formula (4) above can be rephrased as "at least one functional group selected from the group consisting of amino groups and their salts." The component (A) according to the third aspect is an abrasive grain having a functional group represented by the general formula (3) or the general formula (4) above fixed to its surface via a covalent bond, and does not include an abrasive grain having a compound having a functional group represented by the general formula (3) or the general formula (4) above physically or ionically adsorbed to its surface.

In the above formula (4), the anion represented by M ⁻ includes, but is not limited to, anions such as OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , and CN ⁻ , as well as anions derived from acidic compounds.

In the above formula (3) and formula (4), R ¹ to R ³ each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group, but two or more of R ¹ to R ³ may be bonded to form a ring structure.

The hydrocarbon groups represented by R ¹ to R ³ may be any of aliphatic hydrocarbon groups, aromatic hydrocarbon groups, araliphatic hydrocarbon groups, and alicyclic hydrocarbon groups. The aliphatic groups in the aliphatic hydrocarbon groups and araliphatic hydrocarbon groups 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.

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

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

As the aralkyl group, those having 7 to 12 carbon atoms are preferred. Examples of such aralkyl groups 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.

Aryl groups having 6 to 14 carbon atoms are preferred. 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, 3,5-xylyl, naphthyl, and anthryl groups.

The aromatic rings of the above aryl and aralkyl groups may have, as substituents, lower alkyl groups such as methyl and ethyl groups, halogen atoms, nitro groups, amino groups, hydroxyl groups, etc.

The component (A) according to the third aspect can be manufactured by applying, for example, the method described in JP-A-2005-162533. Specifically, first, silica having multiple protrusions on its surface is prepared by applying the method described in JP-A-2007-153732 or JP-A-2013-121631. Next, the silica having multiple protrusions on its surface and the amino group-containing silane coupling agent are thoroughly stirred in an acidic medium to covalently bond the amino group-containing silane coupling agent to the surface of the silica having multiple protrusions on its surface, thereby producing abrasive grains having a functional group represented by the above general formula (3) or (4) and having multiple protrusions on its surface. Here, examples of the amino group-containing silane coupling agent include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, etc.

When the chemical mechanical polishing composition according to this embodiment contains the component (A) according to the third aspect, the content of the component (A) according to the third aspect is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 4 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the component (A) according to the third aspect is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and particularly preferably 16 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. When the content of the component (A) according to the third aspect is within the above range, polishing scratches may be suppressed.

1.2. (B) Heterocyclic Compound The chemical mechanical polishing composition according to this embodiment contains a heterocyclic compound (B). By containing the component (B), the surface of the tungsten film is protected, so that the corrosion of the tungsten surface and the occurrence of defects can be reduced. In addition, by containing the component (B), the surface of the tungsten film is protected, so that residues such as particles can be efficiently removed from the tungsten surface.

The (B) component is preferably a nitrogen-containing heterocyclic compound. Here, the nitrogen-containing heterocyclic compound is an organic compound containing at least one heterocyclic ring selected from a five-membered heterocyclic ring and a six-membered heterocyclic ring having at least one nitrogen atom. Specific examples of the heterocyclic ring include five-membered heterocyclic rings such as pyrrole structure, imidazole structure, triazole structure, thiazole structure, and isothiazolin structure; and six-membered heterocyclic rings such as pyridine structure, pyrimidine structure, pyridazine structure, and pyrazine structure. The heterocyclic ring 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 the nitrogen-containing heterocyclic compounds having such structures, nitrogen-containing heterocyclic compounds having an isothiazolin structure, a thiazole structure, a pyridine structure, a quinoline structure, a benzimidazole structure, or a benzotriazole structure are preferred, and nitrogen-containing heterocyclic compounds having an isothiazolin structure or a thiazole structure are more 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, carboxybenzotriazole, thiazole, benzothiazole, 4-bromothiazole, 2-chlorothiazole, 2-mercaptobenzothiazole, 2-(methylthio)benzothiazole, 2-chlorobenzothiazole, 2-methylbenzothiazole, 5-methoxy-2-methylbenzothiazole, 2-methyl-4,5,7-trifluorobenzothiazole, 2-aminobenzothiazole, 2-amino-6 -methylbenzothiazole, 2-amino-4-methoxybenzothiazole, 4-methyl-2-mercaptobenzothiazole, 3-chloro-1,2-benzisothiazole, 2-(2-hydroxyphenyl)benzothiazole, thiazoline, chlorothiazoline, isothiazolinone, 1,2-benzisothiazolin-3-one, 2-methyl-4,5-trimethylene-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, N-n-butyl-1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-n-octyl-isothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, etc. These nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more.

The content of the (B) component is preferably 0.0001 parts by mass or more, more preferably 0.0005 parts by mass or more, and particularly preferably 0.001 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the (B) component is preferably 0.5 parts by mass or less, more preferably 0.25 parts by mass or less, and particularly preferably 0.15 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. When the content of the (B) component is within the above range, the surface of the tungsten film is protected, so that the corrosion and occurrence of defects on the tungsten surface can be reduced, and residues such as particles can be efficiently removed from the tungsten surface. When the content of the (B) component is less than the above range, it is not possible to prepare a POU (Point of Use) slurry that exhibits good polishing characteristics. If the content of component (B) exceeds the above range, a large amount of component (B) will be adsorbed onto the surface of component (A), the mechanical polishing properties of component (A) will decrease, and it will be difficult to obtain a sufficient polishing rate.

In the chemical mechanical polishing composition according to this embodiment, when the content of the component (A) is MA [parts by mass] and the content of the component (B) is MB [parts by mass], MA/MB = 50 to 10,000. MA/MB is preferably 60 or more, more preferably 75 or more, and particularly preferably 100 or more. MA/MB is preferably 9,000 or less, more preferably 5,000 or less, even more preferably 3,000 or less, and particularly preferably 2,000 or less. When MA/MB is within the above range, the effect of polishing the tungsten film at high speed and the effect of reducing the occurrence of corrosion and defects on the tungsten surface are synergistically improved, and good polishing characteristics are obtained.

1.3. (C) Liquid medium The chemical mechanical polishing composition according to this embodiment contains (C) liquid medium. Examples of (C) liquid medium include 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, a mixed medium of water and alcohol, and it is more preferable to use water. Water is not particularly limited, but pure water is preferable. Water may be blended as the remainder of the constituent materials of the chemical mechanical polishing composition, and there is no particular limit to the content of water.

1.4. Other Components In addition to the components described above, the chemical mechanical polishing composition according to this embodiment may contain, as necessary, an organic acid and a salt thereof (hereinafter, also referred to as an "organic acid (salt)"), a phosphate ester, a water-soluble polymer, a surfactant, an inorganic acid and a salt thereof, a basic compound, or the like.

<Organic acids and their salts>
The chemical mechanical polishing composition according to this embodiment may contain at least one selected from the group consisting of organic acids and their salts. The organic acid (salt) has a synergistic effect with the component (A) to increase the polishing rate of the tungsten film.

The organic acid (salt) is preferably a compound having a carboxy group or a compound 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, malic acid, malonic acid, glutaric acid, succinic acid, benzoic acid, quinolinic acid, quinaldic acid, amidosulfuric acid, propionic acid, and trifluoroacetic acid; amino acids such as glycine, alanine, aspartic acid, glutamic acid, lysine, arginine, tryptophan, dodecylaminoethylaminoethylglycine, aromatic amino acids, and heterocyclic amino acids; imino acids such as alkyliminodicarboxylic acids; 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; and α-olefinsulfonic acids such as tetradecenesulfonic acid. These compounds may be used alone or in combination of two or more.

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

<Phosphate ester>
The chemical mechanical polishing composition according to this embodiment may contain a phosphate ester, which may enhance the effect of reducing the occurrence of dishing by being adsorbed to the surface of the tungsten film.

"Phosphate ester" is a general term for compounds having a structure in which all or some of the three hydrogen atoms in phosphoric acid (O=P(OH) ₃ ) are substituted with organic groups. Among phosphate esters, polyoxyethylene alkyl ether phosphate esters can be preferably used because they are particularly effective in reducing the occurrence of dishing.

Specific examples of polyoxyethylene alkyl ether phosphate esters include polyoxyethylene decyl ether phosphate monoester, polyoxyethylene decyl ether phosphate diester, polyoxyethylene isodecyl ether phosphate monoester, polyoxyethylene isodecyl ether phosphate diester, polyoxyethylene lauryl ether phosphate monoester, polyoxyethylene lauryl ether phosphate diester, polyoxyethylene tridecyl ether phosphate monoester, polyoxyethylene tridecyl ether phosphate diester, polyoxyethylene allyl phenyl ether phosphate monoester, polyoxyethylene allyl phenyl ether phosphate diester, etc. These can be used alone or in combination of two or more. In addition, these polyoxyethylene alkyl ether phosphate esters include monoesters and diesters, and in the present invention, the monoesters and diesters may be used alone or as a mixture.

When the chemical mechanical polishing composition according to this embodiment contains a phosphate ester, the content of the phosphate ester is preferably 0.001 parts by mass or more, and more preferably 0.002 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the phosphate ester is preferably 0.1 parts by mass or less, and more preferably 0.01 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass.

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

Specific examples of water-soluble polymers include polycarboxylic acids, polystyrene sulfonic acids, polyacrylic acids, polymethacrylic acids, polyethers, polyacrylamides, polyvinyl alcohols, polyvinylpyrrolidones, polyethyleneimines, polyallylamines, hydroxyethyl celluloses, etc. These can be used alone 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, and more preferably 40,000 or more and 1,200,000 or less. Here, "weight average molecular weight" refers to the weight average molecular weight in terms of polyethylene glycol measured by GPC (gel permeation chromatography).

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 parts by mass or more, and more preferably 0.002 parts by mass or more, when the total mass of the chemical mechanical polishing composition is 100 parts by mass. The content of the water-soluble polymer is preferably 0.1 parts by mass or less, and more preferably 0.01 parts by mass or less, when the total mass of the chemical mechanical polishing composition is 100 parts by mass.

<Surfactant>
The chemical mechanical polishing composition according to this embodiment may contain a surfactant. The surfactant is not particularly limited, and anionic surfactants, cationic surfactants, nonionic surfactants, etc. may be used. Examples of anionic surfactants include sulfates such as alkyl ether sulfates and polyoxyethylene alkylphenyl ether sulfates; fluorine-containing surfactants such as perfluoroalkyl compounds; and the like. Examples of cationic surfactants include aliphatic amine salts and aliphatic ammonium salts. Examples of nonionic surfactants include nonionic surfactants having triple bonds 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.

<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, and phosphoric acid. The inorganic acid may form a salt with a base added separately to the chemical mechanical polishing composition.

<Basic Compound>
Examples of the basic compound include organic bases and inorganic bases. Examples of the organic base include amines, such as triethylamine, monoethanolamine, tetramethylammonium hydroxide, tetrabutylammonium hydroxide, benzylamine, methylamine, ethylenediamine, diglycolamine, and isopropylamine. Examples of the inorganic base 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.

1.5. pH
The pH of the chemical mechanical polishing composition according to this embodiment is preferably from 2 to 7, more preferably from 2 to 6, and particularly preferably from 2.5 to 5.5. When the pH is within this range, the absolute value of the zeta potential of component (A) in the chemical mechanical polishing composition increases, improving dispersibility, and enabling high-speed polishing of a semiconductor substrate containing a tungsten film while reducing the occurrence of polishing scratches and dishing.

The pH of the chemical mechanical polishing composition according to this embodiment can be adjusted as necessary by appropriately increasing or decreasing the content of the organic acid and its salt, the inorganic acid and its salt, and the basic compound.

In the present invention, pH refers to the hydrogen ion exponent, and its value can be measured using a commercially available pH meter (e.g., a tabletop pH meter manufactured by Horiba, Ltd.) under conditions of 25°C and 1 atmospheric pressure.

1.5. Uses The chemical mechanical polishing composition according to this embodiment can be used as an abrasive for polishing a workpiece provided with a wiring layer containing tungsten, among a plurality of substrates constituting a semiconductor device. For example, in a workpiece having an insulating film having a contact hole and a tungsten film provided in the contact hole and on the insulating film, the composition can be used in a process of polishing the tungsten film on the insulating film to form a tungsten plug (W-plug) embedded in the contact hole in the insulating film.

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

1.7. POU Slurry The chemical mechanical polishing composition according to this embodiment can be used as a POU slurry. The POU slurry may be prepared by using the chemical mechanical polishing composition according to this embodiment as it is, or by adding a liquid medium such as water, the above-mentioned components, and an oxidizing agent such as hydrogen peroxide or a metal ion such as iron to the chemical mechanical polishing composition according to this embodiment and diluting the composition. The method of addition is not particularly limited, and any method may be applied as long as a uniform POU slurry can be prepared. In addition, the mixing order and mixing method of the above-mentioned components are not particularly limited.

2. Polishing Method The polishing method according to one embodiment of the present invention includes a step of polishing a processing object provided with a wiring layer containing tungsten using the above-mentioned POU slurry. Such a POU slurry has a high polishing rate for the tungsten film and can reduce the occurrence of corrosion and defects on the tungsten surface, so that a tungsten plug of good quality can be formed. The polishing method according to this embodiment will be described in detail below with reference to FIGS. 1 to 3.

1 shows an example of a workpiece 100 to which the polishing method according to this embodiment is applied.

(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.

(2) Next, a silicon oxide film 12, which is an insulating film, is formed on the substrate 10 by a CVD method using silane gas and oxygen gas. After that, the silicon oxide film 12 is partially polished by CMP to flatten the surface.

(3) Next, a resist pattern is formed on the silicon oxide film 12. Using this as a mask, the silicon oxide film 12 is etched to form contact holes 14. After the contact holes 14 are formed, the resist pattern is removed.

(4) Next, a tungsten film 16 is deposited on the surface of the silicon oxide film 12 and in the contact holes 14 using the CVD method.

The above steps result in the processed object 100.

2, in the chemical mechanical polishing process, the tungsten film 16 is polished using the above-mentioned POU slurry until the silicon oxide film 12 is exposed. The above-mentioned POU slurry has a high polishing rate for the tungsten film and can reduce corrosion and defects on the tungsten surface, so that a good quality tungsten plug can be formed.

After the chemical mechanical polishing process, it is preferable to remove the abrasive grains remaining on the polished surface. This removal of the abrasive grains can be performed by a normal cleaning method. For example, after brush scrubbing, the abrasive grains adhering to the polished surface can be removed by cleaning with an alkaline cleaning solution of ammonia: hydrogen peroxide: water in a ratio of about 1:1:5 (by mass). Furthermore, as a cleaning solution for impurity metal species adsorbed on the polished surface, for example, an aqueous solution of citric acid, an aqueous mixture of hydrofluoric acid and citric acid, and an aqueous mixture of hydrofluoric acid and ethylenediaminetetraacetic acid (EDTA) can be used.

2.3. Chemical Mechanical Polishing Apparatus In the chemical mechanical polishing step, for example, a chemical mechanical polishing apparatus 200 as shown in Fig. 3 can be used. Fig. 3 is a perspective view showing a schematic diagram of the chemical mechanical polishing apparatus 200. The chemical mechanical polishing is performed by supplying a POU slurry 44 from a slurry supply nozzle 42, and contacting a carrier head 52 holding a semiconductor substrate 50 with a turntable 48 to which a polishing pad 46 is attached while rotating the turntable 48. Note that a water supply nozzle 54 and a dresser 56 are also shown in Fig. 3.

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

Commercially available chemical mechanical polishing devices include, for example, models "EPO-112", "EPO-222", and "F-REX300SII" manufactured by Ebara Corporation; models "LGP-510" and "LGP-552" manufactured by Lapmaster SFT; models "Mirra" and "Reflexion" manufactured by Applied Materials; and model "POLI-762" manufactured by G&P Technology.

3. Examples 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.

3.1. Preparation of abrasive grains <Abrasive grain A>
Colloidal silica (product name: PL-3) manufactured by Fuso Chemical Co., Ltd., spherical colloidal silica having a silica concentration of 20 mass%, pH 7.8, and an average particle size of 70 nm, was purchased and used as is as abrasive grain A. The average particle size of abrasive grain A was calculated from the specific surface area measured by the BET method using an automatic dynamic adsorption surface area measuring device (Micromeritics FlowSorb II 2300 manufactured by Micromeritics).

<Abrasive grain B>
Colloidal silica (product name: TS60C20β) manufactured by Tama Chemicals Co., Ltd., having a silica concentration of 20 mass%, pH 8.1, and an average particle size of 55 nm and having multiple protrusions on the surface, was purchased and used as is as abrasive B. The average particle size of abrasive B was determined in the same manner as for abrasive A.

<Abrasive Grain C>
Colloidal silica (product name: PL-3-C) manufactured by Fuso Chemical Co., Ltd., spherical colloidal silica having a silica concentration of 20 mass%, pH 9.1, and an average particle size of 68 nm and surface-modified with amino groups, was purchased and used as is as abrasive grain C. The average particle size of abrasive grain C was determined in the same manner as abrasive grain A.

<Abrasive grain D>
Colloidal alumina manufactured by Saint-Gobain (product name: Alumina Polishing Slurry 7992 0.20MICS), spherical colloidal alumina with an alumina concentration of 20 mass%, pH 4.2, and average particle size of 187 nm was purchased and used as is as abrasive grain D. The average particle size of abrasive grain D was determined in the same manner as abrasive grain A.

<Abrasive Grain E>
Spherical water glass silica (product name: CATALOID PPS-45PKH) manufactured by JGC Catalysts and Chemicals, having a silica concentration of 40 mass%, pH of 10.1, and an average particle size of 63 nm, was purchased and used as is as abrasive grain E. The average particle size of abrasive grain E was determined in the same manner as abrasive grain A.

3.2. Preparation of chemical mechanical polishing composition The abrasive grains shown in Tables 1 and 2 below were added to a 1 L polyethylene bottle to give a predetermined concentration, and the remaining components were then added to give the composition shown in Tables 1 and 2 below. The pH was then adjusted by adding various acids in the amounts shown in Tables 1 and 2 below. Pure water was then added as a liquid medium to give a total amount of all components of 100 parts by mass to prepare chemical mechanical polishing compositions for each of the Examples and Comparative Examples.

3.3. Evaluation method 3.3.1. Polishing rate evaluation First, a tungsten film blanket wafer "W 6000 Å" with a diameter of 12 inches manufactured by Advanced Materials Technology Co., Ltd. and a silicon oxide film blanket wafer "p-TEOS 10000 Å" manufactured by D&X Co., Ltd. were prepared. Chemical mechanical polishing was carried out using these blanket wafers as the processing objects under the following conditions.

<Polishing conditions>
Polishing equipment: Applied Materials, model "REFLEXION LK"
Polishing pad: Fujibo Co., Ltd., "Multi-hard polyurethane pad; H800-type1 (3-1S) 775"
POU slurry supply rate: 300 mL/min Plate rotation speed: 100 rpm
Head rotation speed: 90 rpm
Head pressing pressure: 2 psi
Polishing rate (Å/min)=(film thickness before polishing−film thickness after polishing)/polishing time

The thickness of the silicon oxide film was calculated by measuring the refractive index using a non-contact optical film thickness measuring device (KLA Tencor, model "F5x"). The thickness of the tungsten film was calculated by measuring the sheet resistance using a sheet resistance measuring device (KLA Tencor, model "RS-100").

　Among the polishing rates obtained above, when the polishing rate of the tungsten film is 150 Å/min or more, it is possible to polish sufficiently for practical use in actual semiconductor polishing, so it is judged to be good and recorded as "A" in the table. When the polishing rate of the tungsten film is less than 150 Å/min, it is judged to be poor because the polishing rate is too slow for practical use and recorded as "B" in the table. Similarly, for the silicon oxide film, when the polishing rate of the silicon oxide film is 1000 Å/min or more, it is possible to polish sufficiently for practical use in actual semiconductor polishing, so it is judged to be good and recorded as "A" in the table. When the polishing rate of the silicon oxide film is less than 1000 Å/min, it is judged to be poor because the polishing rate is too slow for practical use and recorded as "B" in the table.

3.3.2. Corrosion evaluation As shown in Fig. 4, a patterned wafer "MASK754 W PTW" with a diameter of 12 inches manufactured by Advanced Materials Technology Co., Ltd. was prepared. In the patterned wafer 300 shown in Fig. 4, 62 represents "300 mm Si", 64 represents "100 nm PE-TEOS (SiO ₂ )", 66 represents "10 nm Ti", 68 represents "6 nm TiN", and 70 represents "200 nm W". This patterned wafer 300 was used as the processing object and a first stage chemical mechanical polishing was carried out under the following conditions.

<First stage polishing conditions>
Chemical mechanical polishing composition: Cabot Corporation's "W2000" (slurry containing iron ions and hydrogen peroxide)
Polishing pad: Rodel Nitta "IC1000/SUBA400"
・Surface plate rotation speed: 70 rpm
Head rotation speed: 71 rpm
Head load: 50g/ ^cm2
・Chemical mechanical polishing composition supply rate: 200 mL/min ・Polishing time: 150 seconds

Next, the parts by weight of the chemical mechanical polishing composition shown in Tables 1 and 2 below were added to a 10 L polyethylene bottle, and pure water was added to make a POU slurry with a total amount of 100 parts by weight. Using the POU slurry thus prepared, a second stage chemical mechanical polishing was carried out on the polished surface obtained by the first stage chemical mechanical polishing described above under the following polishing conditions.

<Second stage polishing conditions>
Polishing equipment: Applied Materials, model "REFLEXION LK"
Polishing pad: Fujibo Co., Ltd., "Multi-hard polyurethane pad; H800-type1 (3-1S) 775"
POU slurry supply rate: 300 mL/min Plate rotation speed: 100 rpm
Head rotation speed: 90 rpm
Head pressing pressure: 2 psi

The patterned wafer after the second-stage chemical mechanical polishing was observed with an SEM. If there were three or fewer corrosion spots in a 100k field of view, it was determined that sufficient corrosion suppression was possible in actual semiconductor polishing, and was marked as "A" in the table. If there were four or more corrosion spots in a 100k field of view, it was determined that corrosion suppression was poor, and was marked as "B" in the table.

3.3.3. Defect evaluation The patterned wafer after the polishing rate evaluation was observed with a defect inspection device (KLA2351, manufactured by KLA Tencor Corporation). The number of defects was calculated by measuring the pixel size of the defect inspection device at 0.16 μm in array mode, and detecting and evaluating defects extracted from the difference caused by superimposing the comparison image and pixel unit. When there were less than 10 defects of 0.16 μm or more per wafer, the result was judged to be good and was recorded as "A" in the table. When there were 10 defects of 0.16 μm or more per wafer, there was a concern that abnormalities would occur in the electrical characteristics of the wafer, so the result was judged to be bad and was recorded as "B" in the table.

3.4. Evaluation Results Tables 1 and 2 below show the compositions of the chemical mechanical polishing compositions of the Examples and Comparative Examples, as well as the evaluation results.

The following products or reagents were used for each component in Tables 1 and 2 above.
<Heterocyclic compounds>
-Thiazole: Fujifilm Wako Pure Chemical Industries, product name "Thiazole"
・Isothiazolinone: Manufactured by Fujifilm Wako Pure Chemical Industries, trade name "Isothiazolinone"
5-Chloro-2-methyl-4-isothiazolin-3-one: Manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "5-chloro-2-methyl-4-isothiazolin-3-one"
2-n-octyl-4-isothiazolin-3-one: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., trade name "2-n-octyl-4-isothiazolin-3-one"
Pyridine: Fujifilm Wako Pure Chemical Industries, trade name "Pyridine"
Pyrrole: Fujifilm Wako Pure Chemical Industries, product name "Pyrrole"
<Organic Acid>
Citric acid: Fuso Chemical Co., Ltd., product name "Purified Citric Acid (Crystal) L"
Tartaric acid: Fujifilm Wako Pure Chemical Industries, product name "Tartaric acid"
Maleic acid: Fuso Chemical Co., Ltd., product name "refined maleic acid"

The POU slurries of Examples 1 to 13 showed that if the MA/MB ratio was between 50 and 10,000, the tungsten film on the patterned wafer could be polished at high speed, while reducing the corrosion and defects of the tungsten wiring.

The POU slurries of Comparative Examples 1, 4, and 6 are examples in which the MA/MB ratio is less than 50. In these cases, it was found that corrosion and/or defects are likely to occur in the tungsten wiring on the patterned wafer.

The POU slurries of Comparative Examples 2, 3, and 5 are examples in which the MA/MB ratio is 10,000 or more. In these cases, it was found that corrosion of the tungsten wiring on the patterned wafer is likely to occur.

These results show that the chemical mechanical polishing composition of the present invention can polish tungsten films at a high rate and reduce corrosion and defects on the tungsten surface.

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 functions, methods, and results, 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 as the configurations described in the embodiments, or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

10...substrate, 12...silicon oxide film, 14...contact hole, 16...tungsten film, 42...slurry supply nozzle, 44...POU slurry, 46...polishing pad, 48...turntable, 50...semiconductor substrate, 52...carrier head, 54...water supply nozzle, 56...dresser, 62...300 mm Si, 64...100 nm PE-TEOS (SiO ₂ ), 66...10 nm Ti, 68...6 nm TiN, 70...200 nm W, 100...processing object, 200...chemical mechanical polishing apparatus, 300...patterned wafer

Claims

(A) abrasive grains;
(B) a heterocyclic compound;
(C) a liquid medium;
A chemical mechanical polishing composition comprising:
A chemical mechanical polishing composition, in which MA/MB=50 to 10,000, where MA is the content of the component (A) [parts by mass] and MB is the content of the component (B) [parts by mass].
The chemical mechanical polishing composition according to claim 1, wherein the component (B) is a nitrogen-containing heterocyclic compound.
The chemical mechanical polishing composition according to claim 2, wherein the nitrogen-containing heterocyclic compound has an isothiazolinone structure or a thiazole structure.
The chemical mechanical polishing composition according to claim 1 or 2, having a pH of 2 or more and 7 or less.
The chemical mechanical polishing composition according to claim 1 or 2, wherein the component (A) has a functional group represented by the following general formula (1):
-SO 3 - M + ...(1)
(M + represents a monovalent cation.)
The chemical mechanical polishing composition according to claim 1 , wherein the component (A) has a functional group represented by the following general formula (2):
-COO - M + ...(2)
(M + represents a monovalent cation.)
3. The chemical mechanical polishing composition according to claim 1, wherein the component (A) has a functional group represented by the following general formula (3) or the following general formula (4):
-NR 1 R 2 ...(3)
-N + R 1 R 2 R 3 M - (4)
(In the above formulas (3) and (4), R 1 , R 2 and R 3 each independently represent a hydrogen atom or a substituted or unsubstituted hydrocarbon group. M − represents an anion.)
The chemical mechanical polishing composition according to claim 1 or 2, wherein the content of component (A) is 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the chemical mechanical polishing composition.
A polishing method comprising the step of polishing a semiconductor substrate with the chemical mechanical polishing composition of claim 1 or 2.