TWI531642B - Chemical mechanical grinding water dispersions and chemical mechanical grinding methods - Google Patents

Description

Chemical mechanical polishing water dispersion and chemical mechanical polishing method

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

In recent years, new microfabrication technology has been developed along with the high integration and high performance of LSI. Chemical mechanical polishing (hereinafter also referred to as "CMP") is also an LSI manufacturing step, in particular, planarization of an interlayer insulating film in a multilayer wiring forming step, metal plug formation, and buried wiring (damascene wiring) ) The technology that is often used in formation. This damascene wiring technology can achieve simplification of wiring steps, improvement in yield and reliability, and it is considered that its application will be expanded in the future. At present, as a wiring metal for inlaid wiring, copper is mainly used for high-speed logic devices based on low resistance. Further, in the memory device represented by DRAM, aluminum or tungsten is used as the wiring metal for reasons of cost reduction. When discussing both low resistance and low cost, in any device, as a damascene wiring metal, aluminum and its alloys having a second-lower resistance than copper are preferred.

The polishing composition for polishing an aluminum film and its alloy film (hereinafter also referred to as "aluminum film") is required to have an appropriate polishing speed and concave Various properties such as suppression or scratch resistance. In particular, in the polishing of the aluminum film, since aluminum is a soft material, there is a problem that the wide wiring portion is likely to be dented. When the recess is a wafer having an aluminum film on the polishing surface, the surface of the aluminum film is more excessively polished or etched than the entire surface of the wafer by polishing, and the wiring portion of the aluminum film is lowered. When the wiring portion of the aluminum film is recessed, the cross-sectional area of the wiring portion is reduced, so that the resistance is increased and the wiring may be broken.

For the polishing weight for suppressing the depression of the aluminum film, for example, a polishing composition containing ammonium persulfate, cerium oxide, and water is proposed (see, for example, Patent Document 1). Further, it is proposed to contain a polishing material selected from the group consisting of cerium oxide, aluminum oxide, cerium oxide, cerium nitride, and zirconia, an iron (III) compound, and a water polishing composition (see, for example, Patent Document 2).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 6-313164

[Patent Document 2] Japanese Patent Laid-Open No. Hei 10-158634

However, the polishing composition described in Patent Document 1 tends to be easily dented because it has a strong etching effect on the aluminum film. And According to the polishing composition described in Patent Document 2, the surface of the aluminum film is oxidized by the iron (III) compound to form a weak modified layer. Thereby, the polishing rate of the aluminum film can be increased, but it is insufficient in performance from the viewpoint of suppressing the depression. Therefore, it has been demanded to develop a novel chemical mechanical polishing aqueous dispersion which can achieve a sufficient polishing rate and depression suppression for an aluminum film required for a next-generation LSI.

Further, as wiring has become finer in recent years, minute pitting corrosion occurring on the surface of the aluminum film has become a big problem. The pitting is a corrosion pattern that concentrates only on a specific location to produce corrosion holes, and most of which remain passive. The reason why the pitting occurs is known to be caused by partial corrosion of a different portion of the grain boundary portion of the surface of the aluminum film, particularly in an acidic region. Therefore, development of a novel chemical mechanical polishing aqueous dispersion capable of achieving a sufficient polishing rate and depression suppression for an aluminum film required for a next-generation LSI and suppressing occurrence of pitting corrosion has been demanded.

Therefore, in order to solve the above problems, the present invention provides a chemical mechanical polishing aqueous dispersion which has a high polishing rate for aluminum film and its alloy film and suppresses generation of dents in the semiconductor device manufacturing step. And chemical mechanical polishing methods using the same.

Further, in order to solve the above problems, the present invention provides a chemical device capable of suppressing the occurrence of high polishing rate and depression of an aluminum film and an alloy film thereof and suppressing occurrence of pitting corrosion in the semiconductor device. A polishing aqueous dispersion and a chemical mechanical polishing method using the same.

The present invention has been made to solve at least some of the above problems, and can be realized by the following aspects or application examples.

[Application Example 1]

The chemical mechanical polishing aqueous dispersion according to the present invention is a chemical mechanical polishing aqueous dispersion used for the purpose of polishing an aluminum film or an aluminum alloy film in the production step of a semiconductor device, and is characterized in that it contains (A) abrasive grains: 0.1% by mass or more and 10% by mass or less, and (B) a phosphate compound having an organic group having 6 or more carbon atoms: 1% by mass or less.

[Application Example 2]

The chemical mechanical polishing aqueous dispersion according to Application Example 1, wherein the (B) phosphate compound is at least one compound selected from the group consisting of a phosphoric acid monoester, a phosphoric acid diester, and the like.

[Application Example 3]

The chemical mechanical polishing aqueous dispersion according to Application Example 1 or Application Example 2, wherein the component (B) may be a compound represented by the following 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 having 6 to 15 carbon atoms which may contain a hetero atom, and R ² represents a hydrogen atom or an organic group having 6 to 15 carbon atoms which may contain a hetero atom, and the plural exists. Each of AO independently represents an alkyloxy group, and m and n each represent an integer of 0 to 10).

[Application Example 4]

The chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 3, which further contains (C) a phosphate compound having an organic group having 1 to 5 carbon atoms.

[Application 5]

The chemical mechanical polishing aqueous dispersion according to the application example 4, wherein the content 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.

[Application Example 6]

The chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 5, which further contains (D) an organic acid.

[Application Example 7]

The chemical mechanical polishing aqueous dispersion according to Application Example 6, wherein the (D) organic acid may be an organic acid having an acid dissociation index (pKa) of more than 3.

[Application Example 8]

The chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 7, which further contains (E) an oxidizing agent.

[Application Example 9]

The chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 8, which has a pH of from 1 to 7.

[Application Example 10]

The chemical mechanical polishing method of the present invention is characterized in that it comprises using a chemical mechanical polishing aqueous dispersion according to any one of Application Examples 1 to 9 to polish a substrate having an aluminum film or an aluminum alloy film constituting the semiconductor device. step.

According to the chemical mechanical polishing aqueous dispersion of the present invention, in the semiconductor device manufacturing step, the high polishing rate and the depression of the aluminum film and the alloy film thereof can be suppressed.

According to the chemical mechanical polishing aqueous dispersion of the present invention, in the semiconductor device manufacturing step, the high polishing rate and the depression of the aluminum film and the alloy film thereof can be suppressed, and the occurrence of pitting corrosion can be suppressed.

10‧‧‧矽 substrate

12‧‧‧矽Oxide film

14‧‧‧Aluminum film

20‧‧‧Wiring for wiring

42‧‧‧Slurry supply nozzle

44‧‧‧Slurry (chemical mechanical polishing water dispersion)

46‧‧‧ polishing cloth

48‧‧‧ turntable

50‧‧‧Semiconductor substrate

52‧‧‧ Carrying head

54‧‧‧Water supply nozzle

56‧‧‧Finisher

100‧‧‧Processed body

200‧‧‧Chemical mechanical grinding device

Fig. 1 is a cross-sectional view schematically showing a target object to be used in the chemical mechanical polishing method of the present embodiment.

Fig. 2 is a perspective view schematically showing a chemical mechanical polishing apparatus suitable for use in the chemical mechanical polishing method of the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail. The present invention is not limited to the embodiments described below, and various modifications may be made without departing from the scope of the invention.

1. Chemical mechanical polishing water dispersion

The chemical polishing aqueous dispersion according to the embodiment of the present invention contains (A) an abrasive particle: 0.1% by mass or more and 10% by mass or less, and (B) a phosphate 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 of the present embodiment will be described in detail.

1.1. (A) abrasive particles

The chemical mechanical polishing aqueous dispersion of the present embodiment contains (A) abrasive grains (hereinafter also referred to as "(A) component"). The component (A) is exemplified by fuming cerium oxide, colloidal cerium oxide, cerium oxide, aluminum oxide, zirconium oxide, titanium oxide or the like. Among these, colloidal cerium oxide is preferred from the viewpoint of reducing polishing defects such as scratches. The colloidal cerium oxide is produced by a conventional method described in, for example, JP-A-2003-109921. Further, a surface-modified colloid may be used by a conventional method described in JP-A-2010-269985 or J. Ind. Eng. Chem., Vol 12, No. 6, (2006) 911-917, or the like. Ceria.

In particular, the sulfonate group is introduced into the surface of the colloidal ceria. The acid-modified colloidal cerium oxide is preferred in the present invention because it has excellent stability under acidic conditions. The method of introducing a sulfonic acid group on the surface of the colloidal cerium oxide is exemplified by modifying a decane coupling agent having a functional group capable of chemical conversion into a sulfonic acid group on the surface of the colloidal cerium oxide, and converting the functional group into a sulfonic acid group. method. The decane coupling agent is exemplified by a decane coupling agent having a mercapto group such as 3-mercaptopropyltrimethoxydecane, 2-mercaptoethyltrimethoxydecane, 2-mercaptoethyltriethoxydecane; and bis(3-triethyl) A decane coupling agent having a thioether group such as oxyalkylidene propyl)disulfide. The sulfonic acid group can be converted by oxidizing the sulfhydryl or thioether group of the decane coupling agent modified on the surface of the colloidal ceria.

The average particle diameter of the component (A) can be determined by measurement by a particle size distribution measuring apparatus which uses a dynamic light scattering method as a measuring principle. The average particle diameter of the component (A) is preferably 15 nm or more and 100 nm or less, more preferably 30 nm or more and 70 nm or less. When the average particle diameter of the component (A) is within the above range, the practical polishing rate for the aluminum film can be attained, and at the same time, the sedimentation of the component (A) is less likely to occur. Separation of a chemical mechanical polishing aqueous dispersion excellent in storage stability. The particle size distribution measuring device based on the dynamic light scattering method is listed as Beckman. "Delsa Nano S" manufactured by Coulter Co., Ltd.; "Zetasizer nano zs" manufactured by Malvern Co., Ltd.; "LB550" manufactured by Horiba, Ltd. Further, the average particle size measured by the dynamic light scattering method indicates the average particle diameter of the secondary particles formed by the plurality of aggregations of the primary particles.

The content ratio of the component (A) is 0.1% by mass or more and 10% by mass or less based on the total mass of the chemical mechanical polishing aqueous dispersion. It is preferably 0.1% by mass or more and 8% by mass or less, more preferably 0.1% by mass or more and 7% by 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 ratio of the component (A) is less than the above range, the polishing rate of the aluminum film may be remarkably lowered. On the other hand, when the content ratio of the component (A) exceeds the above range, the polishing rate of the aluminum film is almost constant to impair the economy, and the storage stability of the chemical mechanical polishing aqueous dispersion may be deteriorated.

1.2. (B) Phosphate compound having an organic group having 6 or more carbon atoms

The chemical mechanical polishing aqueous dispersion of the present embodiment contains (B) a phosphate compound having an organic group having 6 or more carbon atoms (hereinafter also referred to as "(B) component"). Generally, a phosphate compound refers to a general term of a compound having a structure in which all or a part of three hydrogens of phosphoric acid (O=P(OH) ₃ ) are substituted with an organic group, but the component (B) must be an organic group substituted therewith. The carbon number is 6 or more, and preferably 6 or more and 35 or less, more preferably 7 or more and 25 or less, and most preferably 8 or more and 20 or less. When the carbon number of the organic group is in the above range, the effect of suppressing the occurrence of the depression is obtained by forming an appropriate protective film on the surface of the aluminum film, and the practical polishing rate for the aluminum film can be ensured. When the carbon number of the organic group is less than the above range, a protective film is formed on the surface of the aluminum film, but the protective effect is insufficient, and the effect of suppressing the occurrence of the depression is extremely small.

The mechanism by which the chemical mechanical polishing aqueous dispersion of the present embodiment contains the component (B) and exhibits the effect of suppressing the occurrence of depression is considered to be as follows. That is, by bonding the phosphate group of the (B) component to the presence A hydroxyl group (Al-OH) on the surface of the aluminum film forms a protective film of the component (B) on the surface of the aluminum film. In this case, the organic group in the component (B) appears on the surface, but when the carbon number of the organic group is 6 or more, since the steric hindrance effect is exhibited, it is considered that the etching action can be alleviated. Thereby, it is considered that the surface of the aluminum film can be polished flat.

The organic group is specifically an aliphatic hydrocarbon group having 6 or more carbon atoms (for example, an alkyl group, an alkenyl group or an alkynyl group), an alicyclic hydrocarbon group having 6 or more carbon atoms (for example, a cycloalkyl group or a cycloalkenyl group), and a carbon number. The aromatic hydrocarbon group of 6 or more (for example, a phenyl group, a naphthyl group, etc.), and the polyalkoxy alkane addition product may contain a hetero atom such as oxygen, sulfur or halogen, or a part thereof may be substituted with another substituent.

Further, the component (B) is preferably at least one compound selected from the group consisting of a phosphoric acid monoester, a phosphoric acid diester, and a salt thereof, and the component (B) contains a phosphoric acid monoester (salt) and a phosphoric acid diester (salt). In the case of both, the content ratio is not particularly limited.

The component (B) is preferably a compound represented by the following formula (1).

(R ¹ O(AO) _m )(R ² O(AO) _n )-PO(OH). . . . . (1)

In the above (1), R ¹ represents an organic group having 6 to 15 carbon atoms which may contain a hetero atom, and may have a carbon-carbon double bond. R ² represents hydrogen or an organic group having 6 to 15 carbon atoms which may contain a hetero atom, and may have a carbon-carbon double bond. Further, the organic groups of R ¹ and R ^{2 are} preferably from 7 to 14 carbon atoms, more preferably from 8 to 13 carbon atoms. The hetero atom is exemplified by oxygen, sulfur, halogen, etc., and when the hetero atom is oxygen or sulfur, an ether or a thioether may be formed. The AOs present in the plural are each independently represented by an alkyloxy group. The alkyleneoxy group is exemplified by, for example, an ethyloxy group and a propyloxy group. m and n each represent an integer of 0 to 10.

Specific examples of the component (B) are monohexyl phosphate, monoheptyl phosphate, monooctyl phosphate, mono(2-ethylhexyl phosphate), monodecyl phosphate, monoundecyl phosphate, and phosphoric acid. Phosphate monoesters such as lauryl ester, monotridecyl phosphate, tetradecyl phosphate, monocyclohexyl phosphate, monophenyl phosphate; dihexyl phosphate, diheptyl phosphate, dioctyl phosphate, and phosphoric acid di(2) -ethylhexyl ester), dinonyl phosphate, di-undecyl phosphate, dilauryl phosphate, di-tridecyl phosphate, di-tetradecyl phosphate, dicyclohexyl phosphate, diphenyl phosphate a phosphodiester such as an ester; and an amine salt or an alkylene oxide adduct or the like. The component (B) exemplified above may be used singly or in combination of two or more kinds in any ratio.

The content of the component (B) is 1% by mass or less, preferably 0.003% by mass or more and 0.5% by mass or less, more preferably 0.004% by mass or more and 0.1% by mass or less based on the total mass of the chemical mechanical polishing aqueous dispersion. It is preferably 0.005 mass% or more and 0.05 mass% or less. When the content ratio of the component (B) is in the above range, the effect of suppressing the depression of the aluminum film can be obtained, and at the same time, the practical polishing rate for the aluminum film can be ensured. When the content ratio of the component (B) exceeds the above range, the effect of suppressing the depression can be obtained by forming a protective film on the surface of the aluminum film. However, since the surface of the aluminum film is excessively protected, the polishing rate cannot be obtained. Further, there is a case where the storage stability of the chemical mechanical polishing aqueous dispersion is deteriorated.

1.3. Dispersing media

The chemical mechanical polishing aqueous dispersion of the present embodiment contains a dispersion medium. The dispersion medium is exemplified by water, a mixed medium of water and alcohol, a mixed medium of water and an organic solvent compatible with water, and the like. Among these, a mixed medium of water, water and alcohol is preferably used, and water is preferably used.

1.4. Other additives

The chemical mechanical polishing aqueous dispersion of the present embodiment may further contain (C) a phosphate compound having an organic group having 1 to 5 carbon atoms, (D) an organic acid, (E) an oxidizing agent, and a water-soluble polymer, if necessary. Additives such as anti-corrosion agents, pH adjusters, and surfactants. Hereinafter, each additive will be described.

1.4.1. (C) Phosphate compound having an organic group having 1 to 5 carbon atoms

In the chemical mechanical polishing aqueous dispersion of the present embodiment, (C) a phosphate compound having an organic group having 1 to 5 carbon atoms (hereinafter also referred to as "(C) component") is preferably added. Generally, a phosphate compound refers to a compound having a structure in which all or a part of three hydrogens of phosphoric acid (O=P(OH) ₃ ) are substituted with an organic group, but the component (C) must be an organic compound thereof. The carbon number of the group is 1 or more and 5 or less, preferably 1 or more and 4 or less, more preferably 2 or more and 3 or less. When the carbon number of the organic group is in the above range, an appropriate protective film can be formed on the surface of the aluminum film to exhibit a pitting corrosion inhibitory effect.

In the chemical mechanical polishing aqueous dispersion of the present embodiment, by using the components (B) and (C) in combination, pitting corrosion which may occur on the surface of the aluminum film is effectively suppressed.

Specific examples of the organic group include an aliphatic hydrocarbon group having 1 to 5 carbon atoms (for example, an alkyl group, an alkenyl group, an alkynyl group, etc.) and an alicyclic hydrocarbon group having 3 to 5 carbon atoms (for example, a cycloalkyl group, a cycloalkenyl group, etc.) It may contain a hetero atom such as oxygen, sulfur or halogen, or a part thereof may be substituted with another substituent.

Further, the component (C) is preferably at least one compound selected from the group consisting of a phosphoric acid monoester, a phosphoric acid diester, and a salt thereof, and the component (C) contains a phosphoric acid monoester (salt) and a phosphoric acid diester (salt). In the case of both, the content ratio is not particularly limited.

The component (C) is preferably a compound represented by the following formula (2).

(R ³ O)(R ⁴ O)-PO(OH). . . . . (2)

In the above (1), R ³ represents an organic group having 1 to 5 carbon atoms which may contain a hetero atom, and may have a carbon-carbon double bond. R ⁴ represents a hydrogen atom or hetero atoms of the organic group having a carbon number of 1 to 5, the can having a carbon - carbon double bond. Further, the organic groups of R ³ and R ^{4 are} preferably from 1 to 4 carbon atoms, more preferably from 2 to 3 carbon atoms. The hetero atom is exemplified by oxygen, sulfur, halogen, etc., and when the hetero atom is oxygen or sulfur, an ether or a thioether may be formed. Further, when (C) is a polyvalent ester, the total number of carbon atoms contained in the plurality of organic groups is preferably not more than 5.

Specific examples of the component (C) include monomethyl phosphate, monoethyl phosphate, mono-n-propyl phosphate, monoisopropyl phosphate, mono-n-butyl phosphate, monoisobutyl phosphate, and mono-n-pentyl phosphate. Phosphate monoester such as monoisoamyl phosphate; phosphodiester such as diethyl phosphate, dipropyl phosphate, dibutyl phosphate or diamyl phosphate; and amine salts thereof. The component (C) exemplified above may be used singly or in combination of two or more kinds in any ratio.

The content 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 based on the total mass of the chemical mechanical polishing aqueous dispersion. When the content ratio of the component (C) is in the above range, the pitting corrosion suppressing effect of the aluminum film can be obtained, and the practical polishing rate for the aluminum film can be ensured.

1.4.2. (D) Organic acids

In the chemical mechanical polishing aqueous dispersion of the present embodiment, (D) an organic acid is preferably added. By adding (D) an organic acid, the pitting corrosion inhibitory effect of the aluminum film can be obtained, and at the same time, the practical polishing speed for the aluminum film can be ensured.

In the chemical mechanical polishing aqueous dispersion of the present embodiment, by using the components (B) and (D) in combination, pitting corrosion which may occur on the surface of the aluminum film is effectively suppressed.

(D) The organic acid is preferably an organic acid having an acid dissociation constant (pKa) of more than 3 at 25 °C. By containing an organic acid having a pKa of more than 3, it is easy to form a protective film on the surface of the aluminum film by (D) an organic acid, thereby effectively suppressing pitting corrosion of the aluminum film. Further, when the pKa of the present invention 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 constant (pKa) can be, for example, the method described in (a) The Journal of Physical Chemistry vol. 68, number 6, page 1560 (1964), and (b) the potentiometric automatic titration device manufactured by Hiranuma Sangyo Co., Ltd. (COM) -980Win, etc.), etc., and (c) Chemical Handbook edited by the Chemical Society of Japan (Revision 3) In the version, the acid dissociation constant described in Maruzen Co., Ltd., issued by Maruzen Co., Ltd., and (d) the database of pKaBASF manufactured by Compudrug Co., Ltd., etc.

Specific examples of the (D) organic acid are, for example, 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. Further, the pKa values of the above-exemplified organic acids are shown together 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, and most preferably 0.05% by mass based on the total mass of the chemical mechanical polishing aqueous dispersion. Above 0.75 mass% or less. When the content ratio of the component (D) is within the above range, the pitting corrosion suppressing effect of the aluminum film can be obtained, and the practical polishing rate for the aluminum film can be ensured.

1.4.4. (E) oxidant

In the chemical mechanical polishing aqueous dispersion of the present embodiment, (E) an oxidizing agent is preferably added. (E) The oxidizing agent has a function of facilitating the misalignment reaction with the polishing liquid component by oxidizing the surface of the aluminum film, and making a weak modified layer on the surface of the aluminum film to facilitate the polishing.

The (E) oxidizing agent is exemplified by, for example, ammonium persulfate, potassium persulfate, hydrogen peroxide, iron nitrate, diammonium nitrate, iron sulfate, hypochlorous acid, ozone, potassium periodate, peracetic acid, and the like. These oxidizing agents may be used alone or in combination of two or more. also, Among these oxidizing agents, ammonium persulfate, potassium persulfate, and hydrogen peroxide are preferred, and hydrogen peroxide is more preferred in view of oxidizing power, mutual compatibility with a protective film, and ease of handling.

The content of the (E) 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, and most preferably 0.2% by mass based on the total mass of the chemical mechanical polishing aqueous dispersion. The above 1.5% by mass or less.

1.4.4. Water soluble polymer

In the chemical mechanical polishing aqueous dispersion of the present embodiment, a water-soluble polymer may be further added as needed. The water-soluble polymer has an effect of imparting a moderate viscosity to the chemical mechanical polishing aqueous dispersion. Further, by forming an adsorption film on the surface of the surface to be polished, the occurrence of depressions or the like is suppressed, and the flatness of the surface to be polished is further improved.

The water-soluble polymer is exemplified by an anionic polymer, a cationic polymer, a nonionic polymer, and the like. The anionic polymer is exemplified by, for example, polyacrylic acid, polymethacrylic acid, polystyrenesulfonic acid, and the like. The cationic polymer is exemplified by, for example, a polyethylenimine, a polyvinylpyrrolidone, a polyvinylimidazole or the like. The nonionic polymer is exemplified by, for example, polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polypropylene decylamine or the like. 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 1.2 million, more preferably from 5,000 to 800,000. The term "weight average molecular weight" as used in the present invention means a polymerization measured by a gel permeation chromatography. Weight average molecular weight in terms of styrene.

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

1.4.5. Corrosion inhibitor

Further, in the chemical mechanical polishing aqueous dispersion of the present embodiment, an anticorrosive agent may be further added as needed. The anticorrosive agent mitigates the oxidation of the surface of the aluminum film caused by the (E) oxidizing agent, and simultaneously reacts with the aluminum ion generated by the oxidation of the surface of the aluminum film by the (E) oxidizing agent to form an insoluble complex. Thereby, the flatness of the surface of the aluminum film after the completion of the polishing can be improved.

The anticorrosive agent is not particularly limited, and is preferably a heterocyclic compound. The number of heterocyclic members in the heterocyclic compound is not particularly limited. Further, the heterocyclic compound may be a monocyclic compound or a polycyclic compound having a condensed ring. Specific examples of the heterocyclic compound are pyrrole, pyrazole, imidazole, triazole, tetrazole, pyridine, pyrazine, pyridazine, pyridine, acridine, hydrazine, isoindole, carbazole, anthracene, quinoline. A nitrogen-containing heterocyclic compound such as a azine, a quinoline, an isoquinoline, a naphthyridine, a pyridazine, a quinoxaline, a quinazoline, a porphyrin, an acridine, a thiazole, an isothiazole, an oxazole, an isoxazole or a furazan.

Among these, imidazole is the best. Specific examples of the imidazole are imidazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1,2-dimethylpyrazole, 2-ethyl-4-methylimidazole, 2-iso Propyl imidazole, benzimidazole, 5,6-dimethylbenzimidazole, 2-aminobenzimidazole, 2-chlorobenzimidazole, 2-methylbenzimidazole, 2-(1-hydroxyethyl Benzimidazole, 2-hydroxybenzene Imidazole, 2-phenylbenzimidazole, 2,5-dimethylbenzimidazole, 5-methylbenzimidazole, 5-nitrobenzimidazole, 1H-indole, and the like.

The content ratio of the anticorrosive agent is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 2% by mass or less based on the total mass of the chemical mechanical polishing aqueous dispersion.

1.4.6. pH adjuster

Further, a pH adjuster may be further added to the chemical mechanical polishing aqueous dispersion of the present embodiment as needed. The pH of the chemical mechanical polishing aqueous dispersion can be adjusted to 1 or more and 7 or less by appropriately adding a pH adjuster. The above pH adjusting agent is exemplified by an acidic compound and/or a basic compound.

The acidic compounds are exemplified by organic acids and inorganic acids. The organic acid is exemplified by, for example, malonic acid, maleic acid, malic acid, tartaric acid, oxalic acid, lactic acid, and the like. The inorganic acid is exemplified by phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid or the like. The above-exemplified acidic compounds may be used alone or in combination of two or more.

The basic compound is exemplified by potassium hydroxide, ethylenediamine, TMAH (tetramethylammonium hydroxide), ammonia, or the like.

1.4.7. Surfactant

In the aqueous dispersion for chemical mechanical polishing of the present embodiment, a surfactant may be further added as needed. The surfactant has an effect of imparting a moderate viscosity to the chemical mechanical polishing aqueous dispersion. Chemical mechanical grinding water system The viscosity of the dispersion is preferably adjusted to 0.5 mPa at 25 °C. Less than 10mPa above s. s.

The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. The anionic surfactant is exemplified by a carboxylate such as a fatty acid soap or an alkyl ether carboxylate; a sulfonate such as an alkylbenzenesulfonate, an alkylnaphthalenesulfonate or an α-olefinsulfonate; a sulfate such as an ester salt, an alkyl ether sulfate or a polyoxyethylene ethyl phenyl ether sulfate; a fluorine-containing surfactant such as a perfluoroalkyl compound. The cationic surfactant is exemplified by, for example, an aliphatic amine salt and an aliphatic ammonium salt. Examples of the nonionic surfactant include nonionic surfactants having a triple bond such as acetylene glycol, acetylene glycol ethylene oxide adduct, and acetylene alcohol; and polyethylene glycol type surfactants. Further, polyvinyl alcohol, cyclodextrin, polyvinyl methyl ether, hydroxyethyl cellulose or the like can also be used. These surfactants may be used alone or in combination of two or more.

The content ratio of the surfactant is preferably 0.001% by mass or more and 5% by mass or more, more preferably 0.001% by mass or more and 3% by mass or less, and more preferably 0.01% by mass or more, based on the total mass of the chemical mechanical polishing aqueous dispersion. Below mass%.

1.5. pH

The pH of the chemical mechanical polishing aqueous dispersion of the present embodiment is preferably 1 or more and 7 or less, more preferably 1.5 or more and 4 or less, still more preferably 2 or more and 3 or less. When the pH is in the above range, the practical use of the aluminum film can be achieved. Grinding speed. When the pH exceeds the above range, the polishing rate of the aluminum film may be remarkably lowered.

1.6. Use

The chemical mechanical polishing aqueous dispersion of the present embodiment can achieve a practical polishing rate for the aluminum film and the aluminum alloy film as described above, and has a depression suppressing effect on the surface of the aluminum film and the aluminum alloy film. Therefore, the chemical mechanical polishing aqueous dispersion of the present embodiment is suitable as a polishing material for chemically mechanically polishing a substrate having a wiring formed aluminum film and/or an aluminum alloy film in a semiconductor device manufacturing step. In the present invention, the term "aluminum alloy" means an alloy containing 90% by mass or more of aluminum and other metal elements. Other metal elements are exemplified by Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti, and the like.

1.7. Modification method of chemical mechanical polishing water dispersion

The chemical mechanical polishing aqueous dispersion of the present embodiment can be prepared by dissolving or dispersing the above components in a dispersion medium such as water. The method of dissolving or dispersing is not particularly limited as long as it can be uniformly dissolved or dispersed. Further, the mixing order or mixing method of the above respective components is not particularly limited.

Further, the chemical mechanical polishing aqueous dispersion of the present embodiment can be prepared into a concentrated form of a stock solution, and used in a dispersion medium such as water at the time of use.

2. Chemical mechanical polishing method

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

2.1 treated body

Fig. 1 is a cross-sectional view schematically showing a target object to be used in a chemical mechanical polishing method of the present embodiment. The object to be processed 100 is formed by undergoing the following steps (1) to (4).

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

(2) Next, the hafnium oxide film 12 is formed on the tantalum substrate 10 by a CVD method or a thermal oxidation method.

(3) Next, the tantalum oxide film 12 is patterned. Using this as a mask, the wiring recess 20 is formed on the ruthenium oxide film 12 by, for example, an etching method.

(4) Next, the aluminum film 14 is deposited by a sputtering method so as to fill the wiring recess 20, and the object to be processed 100 is obtained.

2.2. Grinding step

The above-described chemical mechanical polishing aqueous dispersion is used to polish and remove the aluminum film 14 deposited on the tantalum oxide film 12 of the target object 100, and the entire surface is flattened to form an aluminum wiring portion. Chemical mechanical polishing method according to the embodiment In the method, by using the chemical mechanical polishing aqueous dispersion described above, the polishing rate of the aluminum film 14 can be sufficiently increased, and the occurrence of depression of the surface of the aluminum film 14 can be suppressed.

2.3. Chemical mechanical polishing device

For example, the chemical mechanical polishing apparatus 200 shown in Fig. 2 can be used in the aforementioned grinding step. 2 is a perspective view showing the chemical mechanical polishing apparatus 200 in a schematic manner. In the polishing step described above, the slurry (chemical mechanical polishing aqueous dispersion) 44 is supplied from the slurry supply nozzle 42 while the turret 48 to which the polishing cloth 46 is attached is rotated, and is abutted on the carrier for holding the semiconductor substrate 50. The head 52 is performed. Furthermore, FIG. 2 also shows the water supply nozzle 54 and the trimmer 56.

The pressure at which the carrier head 52 is pressed may be selected within the range of 10 to 1,000 hPa, preferably 30 to 500 hPa. Further, the number of revolutions of the turntable 48 and the carrier head 52 can be appropriately selected within the range of 10 to 400 rpm, preferably 30 to 150 rpm. The flow rate of the slurry (chemical mechanical polishing aqueous dispersion) 44 supplied from the slurry supply nozzle 42 can be selected from the range of 10 to 1,000 mL/min, preferably 50 to 400 mL/min.

The commercially available polishing apparatus is exemplified by models "EPO-112" and "EPO-222" manufactured by Ebara Seisakusho Co., Ltd.; "LGP-510" and "LGP-552" manufactured by Larmaster SFT Co., Ltd.; Models "Mirra", "Reflexion", etc.

3. Embodiment

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited by the examples. Moreover, "parts" and "%" in the present embodiment are quality standards unless otherwise specified.

3.1. Modulation of aqueous dispersion of sulfonic acid modified abrasive particles

A mixed liquid of 1522.2 g of tetramethoxy decane and 413.0 g of methanol was added dropwise to a mixed liquid of 787.9 g of pure water, 786.0 g of 26% aqueous ammonia, and 12924 g of methanol while maintaining the liquid temperature at 35 ° C for 55 minutes. A cerium oxide sol using water and methanol as a dispersion medium. The cerium oxide sol was concentrated by heating under normal pressure until it became 5000 mL. 6.0 g of 3-mercaptopropyltrimethoxydecane was added to the concentrate as a decane coupling agent, and the mixture was refluxed at a boiling point to carry out hot aging. Subsequently, pure water was added to keep the capacity constant while replacing methanol and ammonia with water, and the liquid temperature of the cerium oxide sol was temporarily lowered to room temperature when the pH became 8 or less. Next, 53.5 g of a 35% aqueous hydrogen peroxide solution was added and heated again, the reaction was continued for 8 hours, and after cooling to room temperature, an aqueous dispersion of a sulfonic acid-modified abrasive particle (colloidal cerium oxide) was obtained. After the dynamic light scattering particle size measuring apparatus (manufactured by Horiba, Ltd., model "LB550"), a sample obtained by taking out a part of the aqueous dispersion and diluted with ion-exchanged water, and measuring the arithmetic mean diameter as an average particle diameter, It is 30 nm.

3.2. Modification of chemical mechanical grinding water dispersion

The ion exchange water calculated by setting the above-mentioned aqueous dispersion to a specific abrasive particle concentration is placed in a polyethylene bottle having a capacity of 1000 cm ³ , and the acidity is added to each of the amounts shown in the table. The compound (malic acid) or the basic compound (potassium hydroxide) is stirred well. Subsequently, the above-prepared aqueous dispersion, the phosphate ester, the organic acid, the oxidizing agent, and the polyethylene glycol (weight average molecular weight: 7,000) 0.05% by mass, polyvinylpyrrolidone (weight average) were added while stirring. The molecular weight was 6,000 mass%, and the benzimidazole was 0.03 mass%, and the total amount was 100% by mass. Subsequently, the mixture was filtered through a filter having a pore diameter of 5 μm to obtain chemical mechanical polishing aqueous dispersions of Examples 1 to 22 and Comparative Examples 1 to 7. Also, the value in the table indicates the actual amount of blending, and "-" indicates that it is not blended.

3.3. Evaluation method 3.3.1. Chemical mechanical grinding test

The chemical mechanical polishing aqueous dispersion prepared as described above was subjected to chemical mechanical polishing under the following polishing conditions using an aluminum film having a diameter of 8 Å as the object to be polished.

<grinding conditions>

. Grinding device: manufactured by Ebara Seisakusho Co., Ltd., type "EPO-112"

. Polishing pad: RODEL NITTA Co., Ltd., "IC1000/K-Groove"

. Chemical mechanical polishing water dispersion supply rate: 200mL / min

. Platen speed: 90rpm

. Grinding head revolutions: 91rpm

. Grinding head pressing pressure: 140hPa

(1) Calculation of grinding speed of aluminum film

For the aluminum film having a diameter of 8 Å of the object to be polished, the film thickness before polishing was measured in advance using a metal film thickness meter "Omnimap A-RS75tc" manufactured by KLA-Tencor Co., Ltd., and polishing was performed for 1 minute under the above conditions. The film thickness of the object to be polished after the polishing was measured using the same metal film thickness meter, and the difference in film thickness between the polishing and the polishing, that is, the film thickness which was reduced by chemical mechanical polishing, was determined. Next, the polishing rate was calculated from the film thickness and the polishing time which were reduced by chemical mechanical polishing. The evaluation criteria are as follows. The polishing rate and evaluation results of the aluminum film are shown in Tables 1 to 3.

"○": The grinding speed exceeds 100 Å/min.

"X": The grinding speed is 100 Å/min or less.

(2) Evaluation of pitting corrosion

The aluminum film having a diameter of 8 Å of the object to be polished was polished under the above conditions for 1 minute, and then the substrate was sequentially washed and dried. After drying, the surface of the substrate was observed with an optical microscope to determine the presence or absence of fine pitting corrosion. The evaluation criteria are as follows. The evaluation results are shown in Table 1.

"○": No microscopic pitting was observed on the surface of the aluminum film.

"△": Microporous corrosion was observed in one part of the surface of the aluminum film.

"X": Micro-pitting was observed on the entire surface of the aluminum film.

(3) Flatness evaluation

In chemical mechanical polishing in which a pattern wafer having a groove as a wiring pattern is formed, a portion where local over-polishing occurs is known. This is because the unevenness of the groove on the surface of the pattern wafer before the chemical mechanical polishing is formed on the surface of the aluminum film, and the high pressure is locally applied according to the pattern density during the chemical mechanical polishing. Part of the grinding speed is faster. Therefore, the polishing characteristics of the chemical mechanical polishing aqueous dispersion of the present embodiment in the actual use state can be confirmed by polishing and evaluating the patterned wafer of the semiconductor substrate.

For the wafer having the pattern described below, the polishing treatment was performed in the same manner as the above-described polishing conditions except that the polishing time was set to 1 minute, and the flatness (the amount of depression) was evaluated by the following method. The results are shown together in Tables 1 to 3.

<Substrate with pattern>

A test substrate (SEMATECH INTERNATIONAL) made by laminating an aluminum film of 600 nm in a groove pattern of 400 nm in depth after forming a 400-inch PETEOS film into a "SEMATECH 854" pattern. ).

<flatness (sag amount) evaluation>

The height of the aluminum wiring was measured using a high-resolution profiler (KLA-Tencor Co., Ltd., model "HRP240ETCH") for the surface to be polished of the wafer after the polishing process. The amount of depression (Å) in the isolated wiring portion of 5 μm aluminum. The judgment is better when the amount of depression is 0~100Å, and it is better when it is 0~80Å, preferably 0~60Å. When the amount of depression is 0 to 100 Å, it is indicated by "○" in the evaluation column of the table. When the amount of depression exceeds 100 Å, it cannot be applied to the actual device. The evaluation column in the table is indicated by "x".

Here, the compositions and evaluation results of the chemical mechanical polishing aqueous dispersions used in Examples 1 to 22 and Comparative Examples 1 to 7 were summarized in the following Tables 1 to 3.

Further, the following components are used for each of the components in Tables 1 to 3.

. Colloidal cerium oxide (sulfonic acid modified abrasive particles prepared above (colloidal cerium oxide))

. Octyl Phosphate (made by Takemoto Oil Co., Ltd., product name "BIONINE A-70")

. Isopropyl phosphate (manufactured by Takemoto Oil Co., Ltd., product name "BIONINE A-76")

. Butyl phosphate ethyl ester (made by Chengbei Chemical Co., Ltd., product name JP506H)

. Polyoxyethylene ethyl lauryl ether phosphate (made by Kao Co., Ltd., product name "ELECTROSTRIPPER F")

. Polyoxyethylene ethyltridecyl ether phosphate (manufactured by Daiichi Kogyo Co., Ltd., product name "PLYSURF A215C")

. Polyoxyethylene ethyl styrene phenyl ether phosphate (manufactured by Daiichi Kogyo Co., Ltd., product name "PLYSURF AL")

3.4. Evaluation results

According to the chemical mechanical polishing aqueous dispersions of Examples 1 to 22, it was found that the amount of depression of the surface of the aluminum film to be polished was reduced, and a good polishing rate for the aluminum film was obtained. In the chemical mechanical polishing aqueous dispersions of Examples 12 to 16, by using the components (B) and (C) in combination, in addition to the above-described depression suppression effect and high polishing rate, the pitting corrosion inhibitory effect was also confirmed. In the chemical mechanical polishing aqueous dispersions of Examples 17 to 22, the components (B) and (D) were used in combination, in addition to the above-described depression suppression. In addition to the effect and high polishing rate, the pitting corrosion inhibition effect was also confirmed.

In Comparative Example 1 and Comparative Example 2, an example of a chemical mechanical polishing aqueous dispersion which does not contain the component (B) was used. In this case, although a good polishing rate was obtained for the aluminum film, the amount of depression of the surface of the aluminum film was remarkably increased. Moreover, pitting corrosion occurred on the surface of the aluminum film.

In Comparative Example 3, an example of a chemical mechanical polishing aqueous dispersion containing 1% by mass or more of the component (B) was used. In this case, since the protective effect of the protective film formed on the surface of the aluminum film is too strong, the polishing speed is remarkably lowered.

In Comparative Example 4 and Comparative Example 5, an example of a chemical mechanical polishing aqueous dispersion containing no component (B) and containing no component (B) was used. In this case, the pitting corrosion can be suppressed by the protective film formed on the surface of the aluminum film, but the depression cannot be suppressed.

In Comparative Example 6 and Comparative Example 7, an example of a chemical mechanical polishing aqueous dispersion containing no (D) component (B) was used. In this case, the pitting corrosion can be suppressed by the protective film formed on the surface of the aluminum film, but the depression cannot be suppressed.

From the above results, it is understood that the chemical mechanical polishing aqueous dispersion according to the present invention can simultaneously suppress the high polishing rate of the aluminum film and the generation of the depression. Thereby, it was found that good polishing performance can be obtained in a semiconductor device containing an aluminum film.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, the present invention includes substantially the same configuration as that described in the embodiment (for example, a configuration having the same function, method, and result, or And the same effect of the composition). Further, the present invention includes a configuration in which the non-essential portion of the configuration described in the embodiment is replaced. Further, the present invention includes a configuration that can exhibit the same operational effects as those described in the embodiment or a configuration that can achieve the same object. Further, the present invention includes the configuration of the additional conventional technology described in the embodiment.

Claims (9)

A chemical mechanical polishing aqueous dispersion which is a chemical mechanical polishing aqueous dispersion used for the purpose of polishing an aluminum film or an aluminum alloy film in a manufacturing step of a semiconductor device, characterized in that it contains (A) abrasive grains: 0.1% by mass And (B) a phosphate compound having an organic group having 6 or more carbon atoms: 1% by mass or less, and (C) a phosphate compound having an organic group having 1 to 5 carbon atoms. A chemical mechanical polishing aqueous dispersion which is a chemical mechanical polishing aqueous dispersion used for the purpose of polishing an aluminum film or an aluminum alloy film in a manufacturing step of a semiconductor device, characterized in that it contains (A) abrasive grains: 0.1% by mass The above and 10% by mass or less, and (B) a phosphate compound having an organic group having 6 or more carbon atoms: 1% by mass or less, and (D) an organic acid. The chemical mechanical polishing aqueous dispersion according to claim 1 or claim 2, wherein the (B) phosphate compound is at least one compound selected from the group consisting of a phosphoric acid monoester, a phosphoric acid diester, and the salt thereof. . The chemical mechanical polishing aqueous dispersion according to claim 1 or claim 2, wherein the component (B) is a compound represented by the following 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 having 6 to 15 carbon atoms which may contain a hetero atom, and R ² represents a hydrogen atom or may be miscellaneous The organic group of 6 to 15 carbon atoms of the atom, the AO of the plural number each independently represents an alkyleneoxy group, and m and n each represent an integer of 0 to 10). The chemical mechanical polishing aqueous dispersion according to claim 1, wherein the content 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 claim 2, wherein the (D) organic acid is an organic acid having an acid dissociation index (pKa) of more than 3. The chemical mechanical polishing aqueous dispersion according to claim 1 or claim 2, which further contains (E) an oxidizing agent. The chemical mechanical polishing aqueous dispersion according to claim 1 or claim 2 has a pH of 1 to 7. A chemical mechanical polishing method comprising the 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 claim 1 or claim 2.