JP2015019058A - Aqueous dispersion for chemical mechanical polishing, and chemical mechanical polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous dispersion for chemical mechanical polishing capable of achieving both high-polishing speed and suppression of dishing to an aluminum film and its alloy film in a step of manufacturing a semiconductor device, and provide a chemical mechanical polishing method using the same.SOLUTION: The aqueous dispersion for chemical mechanical polishing is an aqueous dispersion for chemical mechanical polishing used for polishing an aluminum film or an aluminum alloy film in a step of manufacturing a semiconductor device, and contains (A) 0.1 mass% or more and 10 mass% or less of abrasive grains, and (B) 1 mass% or less of a phosphoric ester compound having an organic group with 6 or more carbon atoms.

Description

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

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of LSIs. Chemical mechanical polishing (hereinafter also referred to as “CMP”) is one of them, and is frequently used in the LSI manufacturing process, particularly in the multilayer wiring formation process, in the flattening of the interlayer insulating film, the formation of metal plugs, and the formation of embedded wiring (damascene wiring). This technology is used in This damascene wiring technology can simplify the wiring process, improve yield and reliability, and its application is expected to expand in the future. Currently, copper is mainly used as a wiring metal for damascene wiring because of low resistance in high-speed logic devices. Further, in a memory device typified by a DRAM, aluminum or tungsten is used as a wiring metal for the purpose of cost reduction. Considering both low resistance and cost reduction, aluminum and alloys thereof having the second lowest resistance after copper are considered promising as damascene wiring metals in any device.

  A polishing composition for polishing an aluminum film and an alloy film thereof (hereinafter also simply referred to as “aluminum film”) is required to have various performances such as an appropriate polishing rate, dishing suppression, and scratch resistance. In particular, in polishing an aluminum film, since aluminum is a soft material, there is a problem that dishing is likely to occur particularly in a wide wiring portion. Dishing means that when a wafer having an aluminum film on the surface is polished, the aluminum film surface is polished or etched more excessively than the entire wafer surface due to the polishing, whereby a recess is generated in the wiring portion of the aluminum film. . When dishing occurs in the wiring part of the aluminum film, the electrical resistance is increased in order to reduce the cross-sectional area of the wiring part, and the wiring may be disconnected.

  As a polishing composition for suppressing dishing of such an aluminum film, for example, a polishing composition containing ammonium persulfate, silicon dioxide, and water has been proposed (see, for example, Patent Document 1). Further, a polishing composition containing an abrasive selected from the group consisting of silicon dioxide, aluminum oxide, cerium oxide, silicon nitride, and zirconium oxide, an iron (III) compound, and water has been proposed (for example, Patent Documents). 2).

JP-A-6-313164 Japanese Patent Laid-Open No. 10-158634

  However, since the polishing composition described in Patent Document 1 has a strong etching effect on the aluminum film, dishing tends to occur. Moreover, according to the polishing composition described in Patent Document 2, a fragile modified layer can be created by oxidizing the surface of the aluminum film with the iron (III) compound. Thereby, the polishing rate of the aluminum film can be increased, but the performance is insufficient from the viewpoint of suppressing dishing. Therefore, there has been a demand for the development of a new chemical mechanical polishing aqueous dispersion capable of achieving both a sufficient polishing rate and dishing suppression for an aluminum film required for the next generation LSI.

  Furthermore, micro pitting corrosion occurring on the surface of the aluminum film with the further miniaturization of wiring in recent years has become a big problem. This pitting corrosion refers to a corrosion form in which corrosion holes are concentrated only in a specific place, and most of the others remain passive. The reason for the occurrence of pitting corrosion is considered to be due to partial corrosion of non-uniform portions such as crystal grain boundaries on the surface of the aluminum film, particularly in the acidic region. It has been known. Therefore, it is required to develop a new aqueous dispersion for chemical mechanical polishing that can achieve both a sufficient polishing rate for aluminum films required for next-generation LSIs and suppression of dishing, and can suppress the occurrence of pitting corrosion. It was.

  Accordingly, some aspects of the present invention provide a chemical mechanical polishing aqueous system capable of achieving both a high polishing rate for aluminum film and its alloy film and suppression of dishing in the semiconductor device manufacturing process by solving the above-described problems. Dispersion and chemical mechanical polishing method using the same are provided.

  In addition, some aspects of the present invention can solve the above-described problems, and in the semiconductor device manufacturing process, can achieve both a high polishing rate for an aluminum film and its alloy film and suppression of dishing, and can prevent pitting corrosion. An aqueous dispersion for chemical mechanical polishing capable of suppressing the generation and a chemical mechanical polishing method using the same are provided.

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

[Application Example 1]
One aspect of the chemical mechanical polishing aqueous dispersion according to the present invention is:
A chemical mechanical polishing aqueous dispersion for use in polishing an aluminum film or an aluminum alloy film in a manufacturing process of a semiconductor device,
(A) Abrasive grains; 0.1 mass% or more and 10 mass% or less;
(B) a phosphoric acid ester compound having an organic group having 6 or more carbon atoms;
It is characterized by containing.

[Application Example 2]
In the chemical mechanical polishing aqueous dispersion of Application Example 1,
The (B) phosphate ester compound may be at least one compound selected from the group consisting of phosphate monoesters, phosphate diesters, and salts thereof.

[Application Example 3]
In the chemical mechanical polishing aqueous dispersion of Application Example 1 or Application Example 2,
The component (B) can be a compound represented by the following general formula (1).
(R ¹ O (AO) _m ) (R ² O (AO) _n ) —PO (OH) (1)
In (the above formula (1), R ¹ represents an organic group which may 6 to 15 carbon atoms which may contain a hetero atom, R ² represents a hydrogen atom or contain a heteroatom also may number from 6 to 15 carbon An organic group represents a plurality of AOs each independently represents an alkyleneoxy group, and m and n each represents an integer of 0 to 10.)

[Application Example 4]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 3,
Further, (C) a phosphate ester compound having an organic group having 1 to 5 carbon atoms can be contained.

[Application Example 5]
In the chemical mechanical polishing aqueous dispersion of Application Example 4,
The content rate of the said (C) component can be 0.01 to 2 mass% with respect to the total mass of the chemical mechanical polishing aqueous dispersion.

[Application Example 6]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 5,
Furthermore, (D) an organic acid can be contained.

[Application Example 7]
In the chemical mechanical polishing aqueous dispersion of Application Example 6,
The (D) organic acid may be an organic acid having an acid dissociation index (pKa) larger than 3.

[Application Example 8]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 7,
Furthermore, (E) an oxidizing agent can be contained.

[Application Example 9]
In the chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 8,
The pH can be 1-7.

[Application Example 10]
One aspect of the chemical mechanical polishing method according to the present invention is:
A step of polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device using the chemical mechanical polishing aqueous dispersion according to any one of Application Example 1 to Application Example 9 is characterized.

  According to the chemical mechanical polishing aqueous dispersion according to the present invention, it is possible to achieve both high polishing rate for aluminum film and its alloy film and suppression of dishing in the semiconductor device manufacturing process.

  According to the chemical mechanical polishing aqueous dispersion according to the present invention, in the semiconductor device manufacturing process, it is possible to achieve both high polishing rate for aluminum film and its alloy film and suppression of dishing, and to suppress the occurrence of pitting corrosion. Can do.

It is sectional drawing which showed typically the to-be-processed object suitable for use of the chemical mechanical polishing method which concerns on this Embodiment. It is the perspective view which showed typically the chemical mechanical polishing apparatus suitable for use of the chemical mechanical polishing method which concerns on this Embodiment.

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

1. Chemical mechanical polishing aqueous dispersion The chemical mechanical polishing aqueous dispersion according to one embodiment of the present invention comprises: (A) abrasive grains;
It contains at least 10% by mass and (B) a phosphate ester compound having an organic group having 6 or more carbon atoms; 1% by mass or less. Hereinafter, each component contained in the chemical mechanical polishing aqueous dispersion according to the present embodiment will be described in detail.

1.1. (A) Abrasive Grain The chemical mechanical polishing aqueous dispersion according to the present embodiment contains (A) abrasive grains (hereinafter also referred to as “component (A)”). Examples of the component (A) include fumed silica, colloidal silica, ceria, alumina, zirconia, and titanium oxide. Among these, colloidal silica is preferable from the viewpoint of reducing polishing defects such as scratches. As the colloidal silica, for example, those produced by the method described in JP-A-2003-109921 can be used. Also, JP 2010-269985A, J. Org. Ind. Eng. Chem. , Vol. 12, no. 6, (2006) 911-917 or the like, surface-modified colloidal silica may be used.

  In particular, sulfonic acid-modified colloidal silica in which a sulfonic acid group is introduced on the surface of colloidal silica is excellent in stability under acidic conditions, and thus is preferably used in the present invention. As a method for introducing a sulfonic acid group to the surface of colloidal silica, a silane coupling agent having a functional group that can be chemically converted to a sulfonic acid group is modified on the surface of colloidal silica, and then the functional group is converted to a sulfonic acid group. The method of converting into is mentioned. Examples of such silane coupling agents include silane coupling agents having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; bis (3-triethoxy And silane coupling agents having a sulfide group such as (silylpropyl) disulfide. It can be converted into a sulfonic acid group by oxidizing the mercapto group or sulfide group of the silane coupling agent modified on the surface of the colloidal silica.

  (A) The average particle diameter of a component can be calculated | required by measuring with the particle size distribution measuring apparatus which makes a dynamic light scattering method a measurement principle. The average particle size of the component (A) is preferably 15 nm or more and 100 nm or less, and more preferably 30 nm or more and 70 nm or less. When the average particle size of the component (A) is in the above range, a practical polishing rate for the aluminum film can be achieved, and the water for chemical mechanical polishing excellent in storage stability in which the precipitation and separation of the component (A) are difficult to occur. A system dispersion can be obtained. As a particle size distribution measuring apparatus based on the dynamic light scattering method, a nanoparticle analyzer “Delsa Nano S” manufactured by Beckman Coulter; “Zetasizer nano zs” manufactured by Malvern; “LB550” manufactured by Horiba, Ltd. Etc. In addition, the average particle diameter measured using the dynamic light scattering method represents the average particle diameter of secondary particles formed by aggregating a plurality of primary particles.

  The content ratio of the component (A) is 0.1% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 8% by mass or less, more preferably based on the total mass of the chemical mechanical polishing aqueous dispersion. It is 0.1 mass% or more and 7 mass% or less. When the content ratio of the component (A) is in the above range, a practical polishing rate for the aluminum film can be obtained. When the content rate of (A) component is less than the said range, the grinding | polishing rate with respect to an aluminum film may fall remarkably. On the other hand, when the content ratio of the component (A) exceeds the above range, the polishing rate for the aluminum film is almost constant and the economic efficiency is impaired, and the storage stability of the chemical mechanical polishing aqueous dispersion may deteriorate.

1.2. (B) Phosphate ester compound having an organic group having 6 or more carbon atoms The chemical mechanical polishing aqueous dispersion according to the present embodiment comprises (B) a phosphate ester compound having an organic group having 6 or more carbon atoms (hereinafter, (Also referred to as “component (B)”). In general, a phosphoric acid ester compound is a general term for compounds having a structure in which all or part of the three hydrogen atoms of phosphoric acid (O═P (OH) ₃ ) are substituted with organic groups. The component B) requires that the substituted organic group has 6 or more carbon atoms, preferably 6 or more and 35 or less, more preferably 7 or more and 25 or less, and more preferably 8 or more and 20 or less. It is particularly preferred. When the carbon number of the organic group is within the above range, an appropriate protective film is formed on the surface of the aluminum film, so that an effect of suppressing dishing is obtained and a practical polishing rate for the aluminum film is ensured. be able to. When the number of carbon atoms in the organic group is less than the above range, a protective film is formed on the surface of the aluminum film, but its protective action is not sufficient and the effect of suppressing the occurrence of dishing is very small.

  The mechanism by which the chemical mechanical polishing aqueous dispersion according to the present embodiment contains the component (B) to exhibit the effect of suppressing dishing is considered as follows. That is, the phosphoric acid group of (B) component couple | bonds with the hydroxyl group (Al-OH) which exists on the surface of an aluminum film, and the protective film of (B) component is formed on the surface of an aluminum film. Then, the organic group in the component (B) appears on the surface, but if the organic group has 6 or more carbon atoms, a steric hindrance effect appears, and it is considered that the etching action can be relaxed. Thereby, it is considered that the surface of the aluminum film can be polished flat.

  Specific examples of the organic group include aliphatic hydrocarbon groups having 6 or more carbon atoms (for example, alkyl groups, alkenyl groups, and alkynyl groups), and alicyclic hydrocarbon groups having 6 or more carbon atoms (for example, cycloalkyl). Groups, cycloalkenyl groups, etc.), aromatic hydrocarbon groups having 6 or more carbon atoms (eg, phenyl groups, naphthyl groups, etc.), and polyalkylene oxide adducts thereof, and heteroatoms such as oxygen, sulfur, and halogen And a part thereof may be substituted with another substituent.

  The component (B) is preferably at least one compound selected from the group consisting of phosphoric acid monoesters, phosphoric acid diesters, and salts thereof, and the component (B) is a phosphoric acid monoester (salt). ) And phosphoric acid diester (salt), the content ratio is not particularly limited.

The component (B) is preferably a compound represented by the following general formula (1).
(R ¹ O (AO) _m ) (R ² O (AO) _n ) —PO (OH) (1)
The formula (1), R ¹ represents an organic group which may 6 to 15 carbon atoms which may contain a hetero atom, a carbon - may have a carbon-carbon double bond. R ² represents a hydrogen atom or an organic group having 6 to 15 carbon atoms which may contain a hetero atom, and may have a carbon-carbon double bond. In addition, it is preferable that each of the organic groups of R ¹ and R ² has 7 to 14 carbon atoms, and more preferably 8 to 13 carbon atoms. Examples of the hetero atom include oxygen, sulfur, halogen and the like. When the hetero atom is oxygen or sulfur, ether or thioether may be formed. A plurality of AOs each independently represents an alkyleneoxy group. Examples of the alkyleneoxy group include an ethyleneoxy group and a propyleneoxy group. m and n each represents an integer of 0 to 10.

  Specific examples of such component (B) include monohexyl phosphate, monoheptyl phosphate, monooctyl phosphate, mono (2-ethylhexyl) phosphate, monodecyl phosphate, monoundecyl phosphate, monolauryl phosphate, phosphate Phosphoric monoesters such as monotridecyl, tetradecyl phosphate, monocyclohexyl phosphate, monophenyl phosphate; dihexyl phosphate, diheptyl phosphate, dioctyl phosphate, di (2-ethylhexyl) phosphate, didecyl phosphate, diundecyl phosphate And phosphoric acid diesters such as dilauryl phosphate, ditridecyl phosphate, ditetradecyl phosphate, dicyclohexyl phosphate and diphenyl phosphate; and amine salts and alkylene oxide adducts thereof. The component (B) exemplified above may be used alone or in combination of two or more at any ratio.

  The content ratio of the component (B) is 1% by mass or less, more preferably 0.003% by mass or more and 0.5% by mass or less, and further preferably 0.004% with respect to the total mass of the chemical mechanical polishing aqueous dispersion. The content is in the range of mass% to 0.1 mass%, particularly preferably 0.005 mass% to 0.05 mass%. When the content ratio of the component (B) is within the above range, the effect of suppressing dishing of the aluminum film can be obtained, and a practical polishing rate for the aluminum film can be ensured. When the content ratio of the component (B) exceeds the above range, although the effect of suppressing dishing due to the formation of a protective film on the surface of the aluminum film is obtained, the surface of the aluminum film is excessively protected, thereby realizing high-speed polishing. It becomes difficult. In addition, the storage stability of the chemical mechanical polishing aqueous dispersion may deteriorate.

1.3. Dispersion medium The chemical mechanical polishing aqueous dispersion according to the present embodiment contains a dispersion medium. Examples of the dispersion medium include water, a mixed medium of water and alcohol, a mixed medium containing water and an organic solvent having compatibility with water, and the like. Among these, water, a mixed medium of water and alcohol are preferably used, and water is more preferably used.

1.4. Other Additives The chemical mechanical polishing aqueous dispersion according to the present embodiment may further include (C) a phosphate ester compound having an organic group having 1 to 5 carbon atoms, (D) an organic acid, ( E) You may add additives, such as an oxidizing agent, water-soluble polymer, anticorrosive, a pH adjuster, and surfactant. Hereinafter, each additive will be described.

1.4.1. (C) Phosphate ester compound having an organic group having 1 to 5 carbon atoms The chemical mechanical polishing aqueous dispersion according to the present embodiment includes (C) a phosphate ester compound having an organic group having 1 to 5 carbon atoms. (Hereinafter also referred to as “component (C)”) is preferably added. In general, a phosphoric acid ester compound is a general term for compounds having a structure in which all or part of the three hydrogen atoms of phosphoric acid (O═P (OH) ₃ ) are substituted with organic groups. Component C) requires that the carbon number of the substituted organic group be 1 or more and 5 or less, preferably 1 or more and 4 or less, and more preferably 2 or more and 3 or less. When the carbon number of the organic group is in the above range, a pitting corrosion suppressing effect is exhibited by forming an appropriate protective film on the surface of the aluminum film.

  In the chemical mechanical polishing aqueous dispersion according to the present embodiment, pitting corrosion that can occur on the surface of the aluminum film is effectively suppressed by using the component (B) and the component (C) in combination.

  Specifically as said organic group, a C1-C5 aliphatic hydrocarbon group (for example, an alkyl group, an alkenyl group, an alkynyl group, etc.), a C3-C5 alicyclic hydrocarbon group (for example, A cycloalkyl group, a cycloalkenyl group, etc.), which may contain heteroatoms such as oxygen, sulfur, halogen and the like, and a part thereof may be substituted with other substituents.

  The component (C) is preferably at least one compound selected from the group consisting of phosphoric acid monoesters, phosphoric acid diesters, and salts thereof, and the component (C) is a phosphoric acid monoester (salt). ) And phosphoric acid diester (salt), the content ratio is not particularly limited.

The component (C) is preferably a compound represented by the following general formula (2).
^{(R 3 O) (R 4} O) -PO (OH) ····· (2)
The formula (1), R ³ represents an organic group of 1 to 5 carbon atoms which may contain a hetero atom, a carbon - may have a carbon-carbon double bond. R ⁴ represents a C 1-5 organic group which may contain a hydrogen atom or a hetero atom, and may have a carbon-carbon double bond. In addition, it is preferable that each of the organic groups of R ³ and R ⁴ has 1 to 4 carbon atoms, and more preferably 2 to 3 carbon atoms. Examples of the hetero atom include oxygen, sulfur, halogen and the like. When the hetero atom is oxygen or sulfur, ether or thioether may be formed. Moreover, when (C) component is a polyvalent ester, it is preferable that the total number of carbon atoms contained in a plurality of organic groups does not exceed 5.

  Specific examples of such component (C) include monomethyl phosphate, monoethyl phosphate, mono-n-propyl phosphate, monoisopropyl phosphate, mono-n-butyl phosphate, monoisobutyl phosphate, monophosphate. -Phosphoric acid monoesters such as n-pentyl and monoisopentyl phosphate; phosphoric acid diesters such as diethyl phosphate, dipropyl phosphate, dibutyl phosphate and dipentyl phosphate; and amine salts thereof. The component (C) exemplified above may be used alone or in combination of two or more at any ratio.

  The content ratio of the component (C) is preferably 0.01% by mass or more and 2% by mass or less, more preferably 0.1% by mass or more and 1% by mass or less, with respect to the total mass of the chemical mechanical polishing aqueous dispersion. is there. When the content ratio of the component (C) is in the above range, an effect of suppressing pitting corrosion of the aluminum film can be obtained, and a practical polishing rate for the aluminum film can be ensured.

1.4.2. (D) Organic acid It is preferable to add (D) an organic acid to the chemical mechanical polishing aqueous dispersion according to this embodiment. (D) By adding an organic acid, the effect of suppressing pitting corrosion of the aluminum film can be obtained, and a practical polishing rate for the aluminum film can be secured.

  In the chemical mechanical polishing aqueous dispersion according to the present embodiment, pitting corrosion that can occur on the surface of the aluminum film is effectively suppressed by using the component (B) and the component (D) in combination.

  (D) As the organic acid, an organic acid having an acid dissociation index (pKa) at 25 ° C. of greater than 3 is preferably used. By containing an organic acid having a pKa greater than 3, a protective film made of (D) an organic acid is easily formed on the surface of the aluminum film, and pitting corrosion of the aluminum film is effectively suppressed. In the present invention, when the pKa is an organic acid having two or more carboxyl groups, the pKa of the first carboxyl group, that is, pKa1 is used as an index.

  The acid dissociation index (pKa) is calculated by, for example, (a) The Journal of Physical Chemistry vol. 68, number 6, page 1560 (1964), (b) a method using an automatic potentiometric titrator (COM-980Win, etc.) manufactured by Hiranuma Sangyo Co., Ltd., and (c) Chemical Society of Japan It is possible to use the acid dissociation index described in the chemical manual of the edition (revised edition 3, June 25, 1984, published by Maruzen Co., Ltd.), (d) a database such as pKaBASE manufactured by Comprugrug, etc. it can.

  Specific examples of (D) organic acids include fumaric acid (3.07), 3-hydroxybenzoic acid (4.07), 4-hydroxybenzoic acid (4.47), terephthalic acid (3.51). Citric acid (3.09), succinic acid (4.21), isophthalic acid (3.50) and the like. The pKa values of the organic acids exemplified above are also shown in parentheses.

The content ratio of the component (D) is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less, with respect to the total mass of the chemical mechanical polishing aqueous dispersion. Especially preferably, it is 0.05 mass% or more and 0.75 mass% or less. If the content rate of (D) component is the said range, while being able to acquire the pitting corrosion inhibitory effect of an aluminum film, the practical grinding | polishing speed | rate with respect to an aluminum film can be ensured.

1.4.3. (E) Oxidizing agent It is preferable to add (E) an oxidizing agent to the chemical mechanical polishing aqueous dispersion according to this embodiment. (E) The oxidizing agent has an effect of facilitating polishing by creating a fragile modified layer on the surface of the aluminum film by oxidizing the surface of the aluminum film and promoting a complexing reaction with the polishing liquid component.

  (E) Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, hydrogen peroxide, ferric nitrate, diammonium cerium nitrate, iron sulfate, hypochlorous acid, ozone, potassium periodate, and peracetic acid. Can be mentioned. These oxidizing agents may be used individually by 1 type, and may be used in combination of 2 or more type. Of these oxidizers, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferable, and hydrogen peroxide is more preferable in consideration of oxidizing power, compatibility with the protective film, ease of handling, and the like.

  (E) The content of the oxidizing agent is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, with respect to the total mass of the chemical mechanical polishing aqueous dispersion. Especially preferably, it is 0.2 mass% or more and 1.5 mass% or less.

1.4.4. Water-soluble polymer If necessary, a water-soluble polymer may be added to the chemical mechanical polishing aqueous dispersion according to the present embodiment. This water-soluble polymer has an effect of imparting an appropriate viscosity to the chemical mechanical polishing aqueous dispersion. Further, by forming a film by adsorbing to the surface of the surface to be polished, there is an effect of suppressing the occurrence of dishing and the like and further improving the flatness of the surface to be polished.

  Examples of the water-soluble polymer include an anionic polymer, a cationic polymer, and a nonionic polymer. Examples of the anionic polymer include polyacrylic acid, polymethacrylic acid, polystyrene sulfonic acid, and salts thereof. Examples of the cationic polymer include polyethyleneimine, polyvinyl pyrrolidone, and polyvinyl imidazole. Examples of nonionic polymers include polyethylene glycol, polypropylene glycol, polyvinyl alcohol, and polyacrylamide. These water-soluble polymers may be used alone or in combination of two or more.

  The weight average molecular weight of the water-soluble polymer is preferably from 2,000 to 1,200,000, more preferably from 5,000 to 800,000. In the present invention, the “weight average molecular weight” means a polystyrene-reduced weight average molecular weight measured by gel permeation chromatography.

  The content ratio of the water-soluble polymer is preferably 0.002% by mass to 5% by mass, more preferably 0.05% by mass to 1% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion. is there.

1.4.5. Anticorrosive Agent An anticorrosive agent may be further added to the chemical mechanical polishing aqueous dispersion according to this embodiment as necessary. The anticorrosive agent relaxes (E) oxidation of the aluminum film surface by the oxidizing agent and reacts with aluminum ions generated by (E) oxidation of the aluminum film surface by the oxidizing agent to form an insoluble complex. Thereby, the flatness of the surface of the aluminum film after completion of polishing can be improved.

  Although it does not specifically limit as an anticorrosive agent, It is preferable that it is a heterocyclic compound. The number of heterocyclic rings in the heterocyclic compound is not particularly limited. The heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. Specific examples of the heterocyclic compound include pyrrole, pyrazole, imidazole, triazole, tetrazole, pyridine, pyrazine, pyridazine, pyridine, indolizine, indole, isoindole, indazole, purine, quinolidine, quinoline, isoquinoline, naphthyridine, phthalazine, Examples thereof include nitrogen-containing heterocyclic compounds such as quinoxaline, quinazoline, cinnoline, buteridine, thiazole, isothiazole, oxazole, isoxazole and furazane.

  Among these, imidazole is particularly preferable. Specific examples of imidazole include imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, benzimidazole, 5, 6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole, 2-methylbenzimidazole, 2- (1-hydroxyethyl) benzimidazole, 2-hydroxybenzimidazole, 2-phenylbenzimidazole, 2,5 -Dimethylbenzimidazole, 5-methylbenzimidazole, 5-nitrobenzimidazole, 1H-purine and the like.

  The content of the anticorrosive is preferably 0.001% by mass to 5% by mass, more preferably 0.1% by mass to 2% by mass with respect to the total mass of the chemical mechanical polishing aqueous dispersion.

1.4.6. pH adjuster To the chemical mechanical polishing aqueous dispersion according to the present embodiment, a pH adjuster may be further added as necessary. By appropriately adding a pH adjuster, the pH of the chemical mechanical polishing aqueous dispersion can be adjusted to 1 or more and 7 or less. Examples of the pH adjuster include acidic compounds and / or basic compounds.

  Examples of acidic compounds include organic acids and inorganic acids. Examples of the organic acid include malonic acid, maleic acid, malic acid, tartaric acid, oxalic acid, lactic acid, and salts thereof. Examples of the inorganic acid include phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid and the like. The acidic compounds exemplified above may be used singly or in combination of two or more.

  Examples of the basic compound include potassium hydroxide, ethylenediamine, TMAH (tetramethylammonium hydroxide), ammonia and the like.

1.4.7. Surfactant A surfactant may be further added to the chemical mechanical polishing aqueous dispersion according to the present embodiment, if necessary. The surfactant has an effect of imparting an appropriate viscosity to the chemical mechanical polishing aqueous dispersion. The viscosity of the chemical mechanical polishing aqueous dispersion is preferably adjusted to be 0.5 mPa · s or more and less than 10 mPa · s at 25 ° C.

The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Examples of the anionic surfactant include carboxylates such as fatty acid soaps and alkyl ether carboxylates; sulfonates such as alkylbenzene sulfonates, alkylnaphthalene sulfonates, and α-olefin sulfonates; higher alcohol sulfates Examples thereof include sulfates such as ester salts, alkyl ether sulfates and polyoxyethylene alkylphenyl ether sulfates; and fluorine-containing surfactants such as perfluoroalkyl compounds. Examples of the cationic surfactant include aliphatic amine salts and aliphatic ammonium salts. Examples of the nonionic surfactant include nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol; polyethylene glycol type surfactants. Polyvinyl alcohol, cyclodextrin, polyvinyl methyl ether, hydroxyethyl cellulose and the like can also be used. These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.

  The content of the surfactant is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.001% by mass or more and 3% by mass or less, particularly with respect to the total mass of the chemical mechanical polishing aqueous dispersion. Preferably they are 0.01 mass% or more and 1 mass% or less.

1.5. pH
The pH of the chemical mechanical polishing aqueous dispersion according to the present embodiment is preferably 1 or more and 7 or less, more preferably 1.5 or more and 4 or less, and more preferably 2 or more and 3 or less. When the pH is in the above range, a practical polishing rate for the aluminum film can be reliably achieved. When pH exceeds the said range, the polishing rate with respect to an aluminum film may fall remarkably.

1.6. Applications The chemical mechanical polishing aqueous dispersion according to the present embodiment can achieve a practical polishing rate for an aluminum film and an aluminum alloy film as described above, and has a dishing suppression effect on the surface of the aluminum film and the aluminum alloy film. . Therefore, the chemical mechanical polishing aqueous dispersion according to the present embodiment is a polishing for chemical mechanical polishing of a substrate having an aluminum film and / or an aluminum alloy film that forms wiring of a semiconductor device in a manufacturing process of the semiconductor device. Suitable as a material. In the present invention, “aluminum alloy” refers to an alloy containing 90% by mass or more of aluminum and another metal element. Examples of other metal elements include Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti.

1.7. Method for Preparing Chemical Mechanical Polishing Aqueous Dispersion The chemical mechanical polishing aqueous dispersion according to the present embodiment can be prepared by dissolving or dispersing each component described above in a dispersion medium such as water. The method for dissolving or dispersing is not particularly limited, and any method may be applied as long as it can be uniformly dissolved or dispersed. Further, the mixing order and mixing method of the components described above are not particularly limited.

  In addition, the chemical mechanical polishing aqueous dispersion according to the present embodiment can be prepared as a concentrated stock solution and diluted with a dispersion medium such as water when used.

2. Chemical mechanical polishing method A chemical mechanical polishing method according to an embodiment of the present invention includes a step of polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device using the chemical mechanical polishing aqueous dispersion described above. Including. Hereinafter, a specific example of the chemical mechanical polishing aqueous dispersion mechanical polishing method according to the present embodiment will be described in detail with reference to the drawings.

2.1. FIG. 1 is a cross-sectional view schematically showing a target object suitable for use in the chemical mechanical polishing method according to the present embodiment. The target object 100 is formed through the following steps (1) to (4).
(1) First, the silicon substrate 10 is prepared. A functional device such as a transistor (not shown) may be formed on the silicon substrate 10.
(2) Next, a silicon oxide film 12 is formed on the silicon substrate 10 by using a CVD method or a thermal oxidation method.
(3) Next, the silicon oxide film 12 is patterned. Using this as a mask, for example, an etching method is applied to form the recess 20 for wiring in the silicon oxide film 12.
(4) Next, when the aluminum film 14 is deposited by sputtering so as to fill the wiring recess 20, the workpiece 100 is obtained.

2.2. Polishing Step Using the chemical mechanical polishing aqueous dispersion described above, the aluminum film 14 deposited on the silicon oxide film 12 of the object 100 is polished and removed, and the entire surface is flattened to form an aluminum wiring portion. . According to the chemical mechanical polishing method according to the present embodiment, by using the chemical mechanical polishing aqueous dispersion described above, the polishing rate for the aluminum film 14 is sufficiently high and the occurrence of dishing on the surface of the aluminum film 14 is suppressed. can do.

2.3. Chemical Mechanical Polishing Device For the above polishing process, for example, a chemical mechanical polishing device 200 as shown in FIG. 2 can be used. FIG. 2 is a perspective view schematically showing the chemical mechanical polishing apparatus 200. In the above-described polishing step, the carrier holding the semiconductor substrate 50 while supplying the slurry (chemical mechanical polishing aqueous dispersion) 44 from the slurry supply nozzle 42 and rotating the turntable 48 to which the polishing cloth 46 is attached. This is done by bringing the head 52 into contact. In FIG. 2, the water supply nozzle 54 and the dresser 56 are also shown.

  The pressing pressure of the carrier head 52 can be selected within a range of 10 to 1,000 hPa, and preferably 30 to 500 hPa. Moreover, the rotation speed of the turntable 48 and the carrier head 52 can be suitably selected within the range of 10 to 400 rpm, and preferably 30 to 150 rpm. The flow rate of the slurry (chemical mechanical polishing aqueous dispersion) 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.

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

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

3.1. Preparation of Aqueous Dispersion of Sulfonic Acid-Modified Abrasive Grains A mixture of tetramethoxysilane 1522.2 g and methanol 413.0 g was added to a mixture of pure 787.9 g, 26% ammonia water 786.0 g, and methanol 12924 g. While maintaining the temperature at 35 ° C., it was added dropwise over 55 minutes to obtain a silica sol having water and methanol as dispersion media. The silica sol was heated and concentrated under atmospheric pressure to 5000 mL. To this concentrated liquid, 6.0 g of 3-mercaptopropyltrimethoxysilane was added as a silane coupling agent, and the mixture was refluxed at the boiling point and thermally aged. Thereafter, methanol and ammonia were replaced with water while adding pure water to keep the volume constant, and when the pH became 8 or less, the temperature of the silica sol was once lowered to room temperature. Next, 53.5 g of 35% hydrogen peroxide was added and heated again, and the reaction was continued for 8 hours. After cooling to room temperature, an aqueous dispersion of sulfonic acid-modified abrasive grains (colloidal silica) was obtained. Using a dynamic light scattering particle size distribution measuring device (manufactured by Horiba, Ltd., model “LB550”), a sample obtained by extracting a part of this water dispersion and diluting with ion-exchanged water was used to calculate the arithmetic average diameter as the average particle diameter. As a result, it was 30 nm.

3.2. Preparation of Chemical Mechanical Polishing Aqueous Dispersion Ion-exchanged water calculated so that the aqueous dispersion prepared above has a predetermined abrasive concentration is charged into a polyethylene bottle having a capacity of 1000 cm ³ , and an acidic compound ( Malic acid) or a basic compound (potassium hydroxide) was added in such an amount that the pH shown in the table was reached, and the mixture was sufficiently stirred. Thereafter, the aqueous dispersion prepared above with stirring, the phosphate ester described in the table, the organic acid, the oxidizing agent, and 0.05% by mass of polyethylene glycol (weight average molecular weight 7,000), polyvinylpyrrolidone (weight average molecular weight 6) 1,000) 0.05% by mass and 0.03% by mass of benzimidazole were added to make a total of 100% by mass. Then, the chemical mechanical polishing aqueous dispersions of Examples 1 to 24 and Comparative Examples 1 to 9 were obtained by filtering with a filter having a pore diameter of 5 μm. In addition, the value in a table | surface represents the net compounding quantity, "-" represents not mix | blending.

3.3. Evaluation method 3.3.1. Chemical Mechanical Polishing Test Using the chemical mechanical polishing aqueous dispersion prepared above, chemical mechanical polishing was performed under the following polishing conditions using an aluminum film having a diameter of 8 inches as an object to be polished.
<Polishing conditions>
・ Polishing device: Model “EPO-112” manufactured by Ebara Corporation
Polishing pad: Rodel Nitta Co., Ltd. “IC1000 / K-Groove”
・ Chemical mechanical polishing aqueous dispersion supply speed: 200 mL / min ・ Surface plate rotation speed: 90 rpm
-Polishing head rotation speed: 91 rpm
・ Polishing head pressing pressure: 140 hPa

(1) Calculation of polishing rate of aluminum film For an aluminum film having a diameter of 8 inches, which is an object to be polished, the film thickness before polishing is previously measured using a metal film thickness meter “Omnimap A-RS75tc” manufactured by KLA-Tencor. It was measured and polished for 1 minute under the above conditions. The film thickness of the polished object after polishing was similarly measured using a metal film thickness meter, and the difference between the film thickness before and after polishing, that is, the film thickness reduced by chemical mechanical polishing was determined. Then, the polishing rate was calculated from the film thickness decreased by chemical mechanical polishing and the polishing time. The evaluation criteria are as follows. The polishing rate and evaluation results of the aluminum film are also shown in Tables 1 to 3.
“◯”: The polishing rate exceeds 100 Å / min.
“×”: The polishing rate is 100 Å / min or less.

(2) Evaluation of pitting corrosion An aluminum film having a diameter of 8 inches, which is an object to be polished, was polished for 1 minute under the above conditions, and then the substrate was sequentially washed and dried. After drying, the substrate surface was observed using an optical microscope to determine the presence or absence of fine pitting corrosion. The evaluation criteria are as follows. The evaluation results are also shown in Table 1.
“◯”: No fine pitting corrosion is observed on the surface of the aluminum film.
“Δ”: Fine pitting corrosion is observed on a part of the surface of the aluminum film.
“X”: Fine pitting corrosion is observed on the entire surface of the aluminum film.

(3) Evaluation of flatness It is known that in a chemical mechanical polishing of a pattern wafer on which a groove serving as a wiring pattern is formed, a portion that is excessively polished locally occurs. This is because the surface of the pattern wafer before chemical mechanical polishing has irregularities reflecting the grooves that become wiring patterns formed on the surface of the aluminum film, and when chemical mechanical polishing is performed, a locally high pressure is applied according to the pattern density. This is because the polishing speed of the portion increases. For this reason, by polishing and evaluating a patterned wafer imitating a semiconductor substrate, the polishing characteristics of the chemical mechanical polishing aqueous dispersion according to this example in the state of actual use were confirmed.

  A wafer with a pattern described below was subjected to polishing treatment in the same manner as the above polishing conditions except that the polishing time was 1 minute, and the flatness (dishing amount) was evaluated by the following method. The results are also shown in Tables 1 to 3.

<Pattern with pattern>
An 8-inch wafer with a 400 nm PETEOS film formed is processed into a “SEMATECH 854” pattern to form a 400 nm deep groove pattern, and then a test substrate in which a 600 nm aluminum film is laminated (manufactured by SEMATECH INTERNATIONAL) is used. It was.

<Evaluation of flatness (dishing amount)>
Using a high-resolution profiler (model “HRP240ETCH” manufactured by KLA-Tencor Co., Ltd.) on the surface to be polished of the patterned wafer after the polishing process step, the dishing amount (Å) in the aluminum isolated wiring portion having an aluminum wiring width of 5 μm It was measured. It can be judged that the dishing amount is preferably 0 to 100 Å, more preferably 0 to 80 特 に, and particularly preferably 0 to 60 Å. When the dishing amount was 0 to 100 mm, “○” was written in the evaluation column in the table. In addition, when the dishing amount exceeds 100 mm, “x” is shown in the evaluation column in the table, indicating that adaptation to an actual device is impossible.

  Here, the compositions and evaluation results of the chemical mechanical polishing aqueous dispersions used in Examples 1 to 24 and Comparative Examples 1 to 9 are summarized in Tables 1 to 3 below.

In addition, the following were used for each component in Tables 1 to 3.
・ Colloidal silica (sulfonic acid-modified abrasive grains produced above (colloidal silica))
・ Octyl phosphate (product name “Pionin A-70” manufactured by Takemoto Yushi Co., Ltd.)
・ Isopropyl phosphate (Takemoto Yushi Co., Ltd., product name “Pionin A76”)
・ Butoxyethylene phosphate (manufactured by Johoku Chemical Co., Ltd., product name JP506H)
・ Polyoxyethylene lauryl ether phosphate (product name “Electro Stripper F” manufactured by Kao Corporation)
・ Polyoxyethylene tridecyl ether phosphate ester (Daiichi Kogyo Seiyaku Co., Ltd., product name “Plisurf A215C”)
・ Polyoxyethylene styrenated phenyl ether phosphate ester (Daiichi Kogyo Seiyaku Co., Ltd., product name “Plisurf AL”)

3.4. Evaluation Results According to the chemical mechanical polishing aqueous dispersions according to Examples 1 to 24, it was found that the occurrence of dishing amount on the surface of the aluminum film, which is the object to be polished, was reduced, and a good polishing rate for the aluminum film was obtained. did. In the chemical mechanical polishing aqueous dispersions according to Examples 12 to 18, by using the combination of the component (B) and the component (C), in addition to the dishing suppression effect and the high polishing rate, the pitting corrosion suppression effect Was recognized. In the chemical mechanical polishing aqueous dispersions according to Examples 19 to 24, the combination of component (B) and component (D) is used to suppress pitting corrosion in addition to the above dishing suppression effect and high polishing rate. Was recognized.

  Comparative Example 1 and Comparative Example 2 are examples in which a chemical mechanical polishing aqueous dispersion containing no component (B) was used. In such a case, although a good polishing rate for the aluminum film can be obtained, the dishing amount on the surface of the aluminum film is remarkably increased. In addition, pitting corrosion was observed on the entire surface of the aluminum film.

  Comparative Example 3 is an example in which a chemical mechanical polishing aqueous dispersion containing 1% by mass or more of the component (B) is used. In such a case, since the protective action of the protective film formed on the surface of the aluminum film is too strong, the polishing rate is significantly reduced.

  Comparative Example 4 and Comparative Example 5 are examples using the chemical mechanical polishing aqueous dispersion containing no component (B) and only the component (C). In such a case, the occurrence of pitting corrosion can be suppressed by the protective film formed on the surface of the aluminum film, but dishing cannot be suppressed.

  Comparative Example 6 and Comparative Example 7 are examples using the chemical mechanical polishing aqueous dispersion containing no component (B) and only the component (D). In such a case, the occurrence of pitting corrosion can be suppressed by the protective film formed on the surface of the aluminum film, but dishing cannot be suppressed.

  From the above results, it was revealed that the chemical mechanical polishing aqueous dispersion according to the present invention can achieve both a high polishing rate for an aluminum film and suppression of dishing. Thus, it has been found that good polishing performance can be obtained in a semiconductor device including an aluminum film.

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

DESCRIPTION OF SYMBOLS 10 ... Silicon substrate, 12 ... Silicon oxide film, 14 ... Aluminum film, 20 ... Recess for wiring, 42 ... Slurry supply nozzle, 44 ... Slurry (chemical-system polishing aqueous dispersion), 46 ... Polishing cloth, 48 ... Turntable DESCRIPTION OF SYMBOLS 50 ... Semiconductor substrate 52 ... Carrier head 54 ... Water supply nozzle 56 ... Dresser 100 ... Object to be processed 200 ... Chemical mechanical polishing apparatus

Claims (10)

A chemical mechanical polishing aqueous dispersion for use in polishing an aluminum film or an aluminum alloy film in a manufacturing process of a semiconductor device,
(A) Abrasive grains; 0.1 mass% or more and 10 mass% or less;
(B) a phosphoric acid ester compound having an organic group having 6 or more carbon atoms;
An aqueous dispersion for chemical mechanical polishing, comprising   2. The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the (B) phosphate ester compound is at least one compound selected from the group consisting of phosphate monoesters, phosphate diesters, and salts thereof. body. The chemical mechanical polishing aqueous dispersion according to claim 1 or 2, wherein the component (B) is a compound represented by the following general formula (1).
(R ¹ O (AO) _m ) (R ² O (AO) _n ) —PO (OH) (1)
In (the above formula (1), R ¹ represents an organic group which may 6 to 15 carbon atoms which may contain a hetero atom, R ² represents a hydrogen atom or contain a heteroatom also may number from 6 to 15 carbon An organic group represents a plurality of AOs each independently represents an alkyleneoxy group, and m and n each represents an integer of 0 to 10.)   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 3, further comprising (C) a phosphate ester compound having an organic group having 1 to 5 carbon atoms.   The chemical mechanical polishing aqueous dispersion according to claim 4, wherein the content ratio of the component (C) is 0.01% by mass or more and 2% by mass or less based on the total mass of the chemical mechanical polishing aqueous dispersion. .   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 5, further comprising (D) an organic acid.   The aqueous dispersion for chemical mechanical polishing according to claim 6, wherein the organic acid (D) is an organic acid having an acid dissociation index (pKa) larger than 3.   The chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 7, further comprising (E) an oxidizing agent.   The aqueous dispersion for chemical mechanical polishing according to any one of claims 1 to 8, wherein the pH is 1 to 7.   A chemical mechanical polishing comprising a step of polishing a substrate having an aluminum film or an aluminum alloy film constituting a semiconductor device, using the chemical mechanical polishing aqueous dispersion according to any one of claims 1 to 9. Method.

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