JP2008124220A - Polishing liquid - Google Patents

Abstract

【選択図】なしProvided is a polishing liquid suitable for polishing a barrier metal material of a semiconductor device in which polishing proceeds at a sufficient polishing speed in a process of planarizing a surface to be polished by chemical mechanical polishing, and erosion can be effectively suppressed. To do.
(A) A carboxylic acid compound represented by the following general formula (I), (b) colloidal silica particles, and (c) a heterocyclic compound, and having a pH of 2.5 to 4.5. The polishing liquid is in the range. In the following general formula (I), R ^{1 to} R ³ each independently represents a hydrogen atom, a hydroxyl group, a hydroxyalkyl group or an alkyl group, R ⁴ represents a single bond or an alkylene group, and at least ^one of R ^{1 to} R ⁴ One is a hydroxyl group or a hydroxyalkyl group, or has a hydroxyl group or a hydroxyalkyl group as a substituent.

[Selection figure] None

Description

  The present invention relates to a polishing liquid used for manufacturing a semiconductor device, and more particularly to a polishing liquid mainly used for polishing a barrier metal material in planarization in a wiring process of a semiconductor device.

In the development of a semiconductor device typified by a semiconductor integrated circuit (hereinafter referred to as LSI), high density and high integration by miniaturization and lamination of wiring are required for high integration and high speed. For this purpose, various techniques such as chemical mechanical polishing (hereinafter referred to as CMP) have been used.
This CMP is an indispensable technique for performing surface planarization of a film to be processed such as an interlayer insulating film, plug formation, formation of embedded metal wiring, etc., and smoothing the substrate, specifically, extra wiring formation For example, the metal thin film is removed and the excess barrier layer on the insulating film is removed.

A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the surface of the polishing pad with a polishing liquid, press the surface of the substrate (wafer) against the pad, In a state where pressure (polishing pressure) is applied, both the polishing platen and the base are rotated, and the surface of the base is flattened by the generated mechanical friction.
When manufacturing semiconductor devices such as LSI, fine wiring is formed in multiple layers, and before forming metal wiring such as Cu in each layer, diffusion of wiring material into the interlayer insulating film In order to prevent or improve the adhesion of the wiring material to the substrate, a barrier metal layer of Ta, TaN, Ti, TiN or the like is formed.

The planarization of the device is usually performed in two or three steps. In the first step, in the wiring formed by the plating method or the like, an excess wiring forming metal material stacked on the substrate is removed. Metal film CMP (hereinafter referred to as metal film CMP) is performed. This process is performed in one stage or in multiple stages. Thereafter, as a next step, the barrier metal material (barrier metal) exposed on the surface by the metal film CMP is mainly removed, and planarization (hereinafter referred to as barrier metal CMP) with the substrate or the interlayer insulating film as the surface is performed. Is common.
Since the barrier metal material is usually a material harder than the metal material for wiring such as copper wiring, the soft wiring metal film is overpolished and the polished metal surface is not flat but only the center is polished deeper. Concerns that cause dish-like dents (dishing), and that the insulation between metal wires is unnecessarily polished and the surface of multiple metal surfaces forms dish-shaped recesses (erosion) There is a problem.

For this reason, in barrier metal CMP performed next to metal film CMP, the polishing speed of the metal wiring portion and the polishing speed of the barrier metal portion are adjusted to finally form a wiring layer with few steps such as dishing and erosion. It is demanded.
That is, in the barrier metal CMP, when the polishing rate of the barrier metal or the interlayer insulating film is relatively small compared to the metal wiring material, dishing such as polishing of the wiring portion is caused and erosion as a result is generated. Since it is easy, it is desirable that the polishing rate of the barrier metal or the insulating film layer is appropriately high. It is desirable to increase the polishing rate of the barrier metal or the insulating film layer relative to the polishing rate of the metal film CMP because there is a merit of increasing the throughput of the barrier metal CMP in addition to the above-described advantages.

Conventionally, various methods for polishing a barrier layer or a metal film while suppressing dishing have been disclosed. As such a technique, for example, a barrier film polishing composition obtained by adding an imidazole derivative to a polishing liquid for barrier CMP (see Patent Document 1), or a barrier film polishing composition using a benzene ring compound (patent) Reference 2). However, in recent years, it has been strongly desired to achieve further high planarization characteristics, and it has been difficult to say that these conventional polishing liquids have obtained practically sufficient effects.
JP 2004-123930 A JP 2005-285944 A

The objects of the present invention made in view of the above problems are as follows.
That is, the object of the present invention is that, in the manufacture of semiconductor devices, in the polishing of the barrier metal material that follows the bulk polishing of the metal wiring material, the polishing progresses at a sufficient polishing rate, and the generation of erosion is suppressed. An object of the present invention is to provide a polishing liquid suitable for polishing a barrier metal material of a semiconductor device.

As a result of intensive studies, the present inventor has found that the above problem can be solved by using an organic acid having a specific cyclic structure in the polishing liquid for a barrier metal material, and has completed the present invention.
The configuration of the present invention is as follows.
<1> In a chemical mechanical planarization method of a semiconductor device in which a polishing liquid is supplied to a polishing pad on a polishing surface plate and the polishing pad is brought into contact with a surface to be polished and moved relative to the polishing pad. A polishing liquid used for polishing a material,
(A) A polishing liquid containing a compound having a hydroxyl group and a carboxyl group in the molecule, (b) colloidal silica particles, and (c) a heterocyclic compound, and having a pH in the range of 2.5 to 4.5. .
<2> The polishing liquid according to <1>, wherein the compound (a) having a hydroxyl group and a carboxyl group in the molecule is a compound represented by the following general formula (I).

In the general formula (I), R ^{1 to} R ³ each independently represent a hydrogen atom, a hydroxyl group, a hydroxyalkyl group or an alkyl group, R ⁴ represents a single bond or an alkylene group, and at least ^one of R ^{1 to} R ⁴ One is a hydroxyl group or a hydroxyalkyl group, or has a hydroxyl group or a hydroxyalkyl group as a substituent.
<3> The compound represented by the general formula (I) is 2-hydroxypropanoic acid, 2-hydroxymethylpropanoic acid, 2-hydroxybutanoic acid, 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2. -Methylbutanoic acid, 2-hydroxymethyl-2-methylbutanoic acid, 3-hydroxy-2-methylpropanoic acid, 3-hydroxy-2,2-dimethylpropanoic acid, 2-hydroxymethyl-2-methylbutanoic acid, and 2-ethyl The polishing liquid according to <2>, which is a compound selected from the group consisting of 2-hydroxymethylbutanoic acid.
<4> The polishing liquid according to any one of <1> to <3>, comprising (b) 0.5% by mass to 15% by mass of the colloidal silica particles.
<5> The polishing liquid according to any one of <1> to <3>, wherein the (b) colloidal silica particles contain two or more types of colloidal particles having different particle sizes or shapes.
<6> The polishing liquid according to any one of <1> to <3>, wherein an average particle diameter of the (b) colloidal silica particles is in a range of 20 to 50 nm.

<7> The heterocyclic compound is 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [ <1> to <6>, which is one or more compounds selected from N, N-bis (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole. The polishing liquid as described.
<8> The polishing liquid according to any one of <1> to <7>, further comprising (d) a quaternary alkyl ammonium compound.
<9> The polishing liquid according to any one of <1> to <8>, further comprising (e) an anionic surfactant.

  According to the present invention, in the manufacture of a semiconductor device, in the polishing of the barrier metal material that is performed following the bulk polishing of the metal wiring material, the semiconductor progresses at a sufficient polishing rate and suppresses the occurrence of erosion. A polishing liquid suitable for polishing a barrier metal material of a device can be provided.

Hereinafter, specific embodiments of the present invention will be described.
[Polishing liquid]
The polishing liquid of the present invention is a polishing liquid mainly used for polishing a barrier metal material, and (a) a compound having a hydroxyl group and a carboxyl group in the molecule (hereinafter, appropriately referred to as (a) a specific organic acid), It contains (b) colloidal silica particles and (c) a heterocyclic compound, and has a pH in the range of 2.5 to 4.5.

  In the present invention, the “polishing liquid” means not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the polishing liquid. The concentrated liquid or the concentrated polishing liquid means a polishing liquid prepared with a higher solute concentration than the polishing liquid used for polishing, and is diluted with water or an aqueous solution when used for polishing. And used for polishing. The dilution factor is generally 1 to 20 volume times. In this specification, “concentration” and “concentrated liquid” are used in accordance with conventional expressions meaning “thick” and “thick liquid” rather than the state of use, and generally involve physical concentration operations such as evaporation. The term is used in a different way from the meaning of common terms.

That is, the concentrated liquid or the concentrated polishing liquid means a polishing liquid prepared with a higher solute concentration than the polishing liquid used for polishing, and when used for polishing, It is diluted and used for polishing. The dilution factor is generally 1 to 20 volume times.
In the present invention, the “polishing liquid” means not only a polishing liquid used for polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of the polishing liquid.

Hereinafter, each component which comprises the polishing liquid of this invention is demonstrated sequentially.
[(A) Compound having a hydroxyl group and a carboxyl group in the molecule (specific organic acid)]
The specific organic acid (a), which is a characteristic component of the present invention, has a hydroxyl group and a carboxy group in the molecule, and is specifically represented by the following general formula (I). A compound.

In the general formula (I), R ^{1 to} R ³ each independently represent a hydrogen atom, a hydroxyl group, a hydroxyalkyl group or an alkyl group, R ⁴ represents a single bond or an alkylene group, and at least ^one of R ^{1 to} R ⁴ One is a hydroxyl group or a hydroxyalkyl group, or has a hydroxyl group or a hydroxyalkyl group as a substituent.
Especially, as R < ¹ > -R < ³ >, alkyl groups, such as a hydrogen atom, a methyl group, and an ethyl group, a hydroxyl group, a hydroxymethyl group, a hydroxyethyl group, etc. are preferable.
When R ⁴ represents an alkylene group, a methylene group or an ethylene group is preferable, and a methylene group is more preferable.

Here, at least one of R ^{1 to} R ⁴ must be a hydroxyl group or a hydroxyalkyl group, or have a hydroxyl group or a hydroxyalkyl group as a substituent, and the hydroxyl group present in the molecule has a polishing performance. From the viewpoint, it is preferably 1 to 3, more preferably 1 or 2.
As the hydroxyl position, at least one of R ^{1 to} R ³ is a hydroxyl group or a hydroxyalkyl group, R ⁴ is a methylene group or an ethylene group, and a hydroxyl group is added to one of the carbons constituting the alkylene group. Aspects, etc. are preferred.

  Specific examples of the specific organic acid (a) represented by the general formula (I) include 2-hydroxypropanoic acid, 2-hydroxymethylpropanoic acid, 2-hydroxybutanoic acid, and 2-hydroxy-2-methyl. Propanoic acid, 2-hydroxy-2-methylbutanoic acid, 2-hydroxymethyl-2-methylbutanoic acid, 3-hydroxy-2-methylpropanoic acid, 3-hydroxy-2,2-dimethylpropanoic acid, 3-hydroxymethyl-2 -Methylbutanoic acid, 2-ethyl-2-hydroxymethylbutanoic acid and the like. Of these, 2-hydroxymethylpropanoic acid and 2-hydroxy-2-methylpropanoic acid are preferred from the viewpoint of polishing performance.

The (a) specific organic acid used in the polishing liquid of the present invention may be used alone or in combination of two or more.
The content of the specific organic acid (a) in the polishing liquid is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass.

[(A-2) Other organic acids]
In the polishing liquid of the present invention, in addition to the specific organic acid (a), a general organic acid usually used for the polishing liquid can be used in combination as long as the effects of the present invention are not impaired.
As general organic acids that can be used in combination, lactic acid, glycolic acid, malic acid, tartaric acid, citric acid, maleic acid, and derivatives thereof are particularly preferably used. These organic acids can be used alone or in combination of two or more.

The amount of (a-2) other organic acid that can be used in combination is preferably 0 to 5% by mass, and preferably 0 to 3% by mass, relative to the (a) specific organic acid.
Moreover, it can be 0.01-20 mass% as a total amount of (a) specific organic acid and (a-2) organic acid which can be used together with respect to the polishing liquid at the time of use, and 0.1-20 mass % Is preferable, 0.1 to 10% by mass is more preferable, and 0.1 to 5% by mass is particularly preferable.

[(B) Colloidal silica particles]
The polishing liquid used in the present invention contains colloidal silica particles as a constituent component. Colloidal silica particles are contained as abrasive particles.
Examples of the method for producing the colloidal silica particles include silicon alkoxides such as Si (OC ₂ H ₅ ) ₄ , Si (sec-OC ₄ H ₉ ) ₄ , Si (OCH ₃ ) ₄ , and Si (OC ₄ H ₉ ) _4. It can be obtained by hydrolyzing the compound by a sol-gel method. Such first and second colloidal particles (for example, first and second colloidal silica particles) have a very sharp particle size distribution.

  The primary particle size of the colloidal silica particles is a particle size cumulative curve showing the relationship between the particle size of the colloidal silica particles and the cumulative frequency obtained by integrating the number of particles having the particle size, and the cumulative frequency of this curve is the point where the cumulative frequency is 50%. This means the particle diameter at. The particle size of the colloidal particles represents an average particle size determined in the particle size distribution obtained from the dynamic light scattering method. For example, LB-500 manufactured by HORIBA, Ltd. is used as a measuring device for obtaining the particle size distribution.

The average particle size of the colloidal silica particles contained is preferably 5 to 60 nm, more preferably 5 to 30 nm, and particularly preferably 20 to 50 nm. Particles of 5 nm or more are preferable for the purpose of achieving a sufficient polishing speed. The particle diameter is preferably 60 nm or less for the purpose of preventing excessive frictional heat during polishing.
Here, the average particle size refers to the average particle size of particles before being used for polishing, in a state of being mixed in a slurry form in the polishing liquid. In addition, because of the physical properties of the colloidal silica particles, the average particle size of the colloidal silica particles before blending and the average particle size of the particles present in the polishing liquid are almost the same. Thus, the average particle diameter of the particles in the polishing liquid can be obtained.

Only one type of colloidal silica particles may be used, or two or more types may be used in combination. When used in combination, two or more types of colloidal particles having different particle sizes or shapes may be used in combination.
It is preferable from the viewpoint of achieving a high polishing rate.
For example, as a combination having different particle sizes, a large particle size silica having an average particle size of 30 to 100 nm and a small particle size silica having an average particle size of 20 to 60 nm are mixed at a mass ratio of 1:10 to 10: 1. By using in combination, the polishing rate for each film type can be improved.
In addition, particles having different shapes, for example, spherical silica close to a true sphere, non-spherical particles having a ratio of major axis to minor axis (major axis / minor axis) of 1.2 to 5.0, and bowl-shaped silica For example, a spherical silica fine particle having an average particle diameter of about 10 to 50 nm and a non-spherical silica fine particle having a long diameter / single diameter ratio of 1 to 5 and a mass ratio of By using together at a ratio of 1:10 to 10: 1, it is possible to improve the polishing rate especially for the insulating film.
Such non-spherical colloidal silica particles are described in detail in Japanese Patent Application No. 2005-366712, and the description can also be applied to the present application.

  It is preferable that the concentration of the abrasive particles composed of the composite contained is contained in the polishing liquid at the time of use in a ratio of 0.5 to 15% by mass in total. More preferably, it is the range of 1-10 mass%. In this range, it is preferable because a sufficient polishing speed can be achieved and generation of excessive frictional heat during polishing can be suppressed.

[(C) heterocyclic compound]
The polishing liquid of the present invention comprises at least one (c) heterocyclic compound as a compound that forms a passive film on a metal surface to be polished, suppresses a chemical reaction on the substrate, and adjusts the polishing rate and the like. contains.
Here, the “heterocyclic compound” is a compound having a heterocyclic ring containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom or a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. A heteroatom means only those atoms that form part of a heterocyclic ring system, either external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of are not meant.
The heteroatom is preferably a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, more preferably a nitrogen atom, a sulfur atom, an oxygen atom, and a selenium atom. And particularly preferably a nitrogen atom, a sulfur atom and an oxygen atom, and most preferably a nitrogen atom and a sulfur atom.

  In addition, as for the heterocyclic ring serving as the mother nucleus, the number of members of the heterocyclic ring of the heterocyclic compound is not particularly limited, and may be a monocyclic compound or a polycyclic compound having a condensed ring. The number of members in the case of a single ring is preferably 5 to 7, particularly preferably 5. When it has a condensed ring, the number of rings is preferably 2 or 3.

Specific examples of these heterocyclic rings include the following. However, it is not limited to these.
Pyrrole ring, thiophene ring, furan ring, pyran ring, thiopyran ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, pyrrolidine ring, Pyrazolidine ring, imidazolidine ring, isoxazolidine ring, isothiazolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, chroman ring, thiochroman ring, isochroman ring, isothiochroman ring, indoline ring, isoindoline ring, pyringin Ring, indolizine ring, indole ring, indazole ring, purine ring, quinolidine ring, isoquinoline ring, quinoline ring, naphthyridine ring, phthalazine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine Perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, anti-lysine ring, thiadiazole ring, oxadiazole ring, triazine ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzthiazole ring, benz A thiadiazole ring, a benzfuroxan ring, a naphthimidazole ring, a benztriazole ring, a tetraazaindene ring and the like are mentioned, and a triazole ring and a tetrazole ring are more preferred.

Next, substituents that the heterocyclic ring may have will be described.
Examples of the substituent that can be introduced into the heterocyclic ring include the following. However, it is not limited to these.
That is, for example, a halogen atom, an alkyl group (a linear, branched or cyclic alkyl group, which may be a polycyclic alkyl group such as a bicycloalkyl group or an active methine group), an alkenyl group, an alkynyl group Group, aryl group, amino group and heterocyclic group.
Further, two or more of the plurality of substituents may be bonded to each other to form a ring. For example, an aromatic ring, an aliphatic hydrocarbon ring, a heterocyclic ring, or the like may be formed, or these may be further combined. Thus, a polycyclic fused ring may be formed. Specific examples of the ring formed include a benzene ring, naphthalene ring, anthracene ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, and thiazole ring.

Specific examples of the heterocyclic compound that can be particularly preferably used in the present invention include, but are not limited to, the following.
That is, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4- Amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino- 1,2,4-triazole, benzotriazole and the like.

  The heterocyclic compound is more preferably benzotriazole and its derivatives. Examples of the derivative include 5,6-dimethyl-1,2,3-benzotriazole (DBTA), 1- (1,2-dicarboxyethyl) benzotriazole (DCEBTA), 1- [N, N-bis ( Hydroxyethyl) aminomethyl] benzotriazole (HEABTA) and 1- (hydroxymethyl) benzotriazole (HMBTA) are preferred.

The heterocyclic compound in this invention may be used independently and may be used together 2 or more types.
In addition, the heterocyclic compound in the present invention can be synthesized according to a conventional method, or a commercially available product may be used.

  The addition amount of the heterocyclic compound in the present invention is preferably in the range of 0.01 to 2% by mass, more preferably 0.05 to 1% with respect to the polishing liquid used for polishing as a total amount. It is the range of mass%, More preferably, it is the range of 0.05-0.5 mass%.

[(D) Quaternary alkyl ammonium compound]
The polishing liquid of the present invention preferably contains (d) a quaternary alkyl ammonium compound.
Preferred quaternary alkylammonium compounds that can be used in the present invention include, for example, monoethanolamine, diethanolamine, triethanolamine, methylethanolamine, monopropanol obtained by adding ethylene oxide, propylene oxide, etc. to ammonia, alkylamine, or polyalkylpolyamine. Amino alcohols such as amine, dipropanolamine, tripropanolamine, methylpropanolamine, monobutanolamine, aminoethylethanolamine; tetramethylammonium hydroxide, choline salt and the like.
(D) The content of the quaternary alkyl ammonium compound is preferably in the range of 0.001 to 1% by mass, more preferably 0.01 to 0.5% by mass in the polishing liquid during use. It is a range.

[(E) Anionic surfactant]
The polishing liquid of the present invention preferably contains (e) an anionic surfactant.
The surfactant has an action of reducing the contact angle of the surface to be polished and promoting uniform polishing. As the anionic surfactant to be used, those selected from the following group are suitable.

  For example, carboxylate, sulfonate, sulfate ester salt, phosphate ester salt can be mentioned. As carboxylate, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxylate, acylation Peptides; alkyl sulfonates, sulfosuccinates, α-olefin sulfonates, N-acyl sulfonates; sulfate esters such as sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxy Ethylene or polyoxypropylene alkyl allyl ether sulfate, alkyl amide sulfate; As phosphate ester salts, mention may be made of alkyl phosphates, polyoxyethylene or polyoxypropylene alkyl allyl ether phosphates.

Preferable specific examples of the anionic surfactant include dodecylbenzene sulfonate.
The addition amount of the anionic surfactant is preferably 0.01 g to 5 g, more preferably 0.01 g to 3 g in 1 L of a polishing liquid used for polishing as a total amount. It is especially preferable to set it as -1.5g. Moreover, when using dodecylbenzenesulfonate, the addition amount is preferably 0.001 to 1% by mass, more preferably 0.01 to 1% by mass in the polishing liquid when used for polishing. .

(Other surfactants)
In the present invention, in addition to an anionic surfactant, other surfactants can be used in combination. Other surfactants that can be used in combination include the following.
As cationic surfactants, for example, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium chloride salts, benzethonium chloride, pyridinium salts, imidazolinium salts; as amphoteric surfactants, carboxybetaine type, aminocarboxylic Examples thereof include acid salts, imidazolinium betaines, lecithins, and alkylamine oxides.

  Nonionic surfactants include, for example, ether type, ether ester type, ester type, and nitrogen-containing type, and ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxy Examples include ethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, and ether ester types such as glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, ester type As polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol Esters, sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like. Moreover, a fluorine-type surfactant etc. are mentioned.

  In addition, when the object to be polished is a silicon substrate for a large scale integrated circuit or the like, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable. Therefore, these surfactants are acids or ammonium salts thereof. Is preferred. This is not the case when the substrate is a glass substrate or the like.

  The total amount of other surfactants added is preferably 0.001 g to 10 g, more preferably 0.01 g to 5 g in 1 liter of polishing liquid used for polishing. It is particularly preferable to set it to ˜3 g.

(Hydrophilic polymer)
Moreover, the polishing liquid of the present invention may further contain other components, and a preferable component includes a hydrophilic polymer. The above components contained in the polishing liquid may be used alone or in combination of two or more.
Similar to the surfactant, the hydrophilic polymer has an action of reducing the contact angle of the surface to be polished and has an action of promoting uniform polishing. As the hydrophilic polymer to be used, those selected from the following group are suitable.

  Examples of the hydrophilic polymer include esters such as glycerin ester, sorbitan ester, methoxyacetic acid, ethoxyacetic acid, 3-ethoxypropionic acid and alanine ethyl ester; polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene Glycol alkenyl ether, alkyl polyethylene glycol, alkyl polyethylene glycol alkyl ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, polypropylene glycol alkyl ether, polypropylene glycol alkeni Ether, alkyl polypropylene glycol, alkyl polypropylene glycol alkyl ether, alkyl polypropylene glycol alkenyl ether, alkenyl polypropylene glycol, alkenyl polypropylene glycol alkyl ether, alkenyl polypropylene glycol alkenyl ether, and other ethers; alginic acid, pectic acid, carboxymethylcellulose, curdlan, pullulan, etc. Amino acid salts such as glycine ammonium salt and glycine sodium salt; polyaspartic acid, polyglutamic acid, polylysine, polymalic acid,

Polymethacrylic acid, polyammonium methacrylate, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, polyacrylic Ammonium salt, polyacrylic acid sodium salt, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt and polyglyoxylic acid and other polycarboxylic acids and salts thereof; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein; methyl Tauric acid ammonium salt, methyl tauric acid sodium salt, methyl sodium sulfate salt, ethylammonium sulfate salt, butylammonium sulfate salt, vinylsulfonic acid sodium salt, 1- Rylsulfonic acid sodium salt, 2-allylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, 3-ethoxypropylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, Examples include sulfonic acids such as 3-ethoxypropylsulfonic acid sodium salt and sulfosuccinic acid sodium salt; and amides such as propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide, and sulfanilamide.
Among the above exemplified compounds, cyclohexanol, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.
The weight average molecular weight of these hydrophilic polymers is preferably 500 to 100,000, particularly 2,000 to 50,000.

  The total amount of the hydrophilic polymer added is preferably 0.001 g to 10 g, more preferably 0.01 g to 5 g, and more preferably 0.1 g to 3 g in 1 liter of polishing liquid when used for polishing. It is particularly preferable that In this range, a sufficient effect of addition can be obtained, and the CMP rate is properly maintained.

(Oxidant)
The polishing liquid of the present invention can further use an oxidizing agent in combination. An oxidizing agent is a compound that can oxidize a metal to be polished.
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt.
Examples of the iron (III) salt include, in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III), iron bromide (III), and iron (III) Organic complex salts are preferably used.

The addition amount of the oxidizing agent can be adjusted by the dishing amount at the initial stage of the barrier metal CMP. When the amount of dishing at the initial stage of the barrier metal CMP is large, that is, when it is not desired to polish the metal wiring material so much in the barrier metal CMP, it is desirable to add a small amount of oxidizing agent, and the amount of dishing is sufficiently small. When it is desired to polish the metal wiring material at a high speed, it is desirable to increase the amount of the oxidizing agent added.
As described above, it is desirable to change the addition amount of the oxidizing agent depending on the dishing state in the initial stage of the barrier metal CMP, but it is usually preferable to set the amount to 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. 0.05 mol to 0.6 mol is particularly preferable.

(PH of polishing liquid)
The polishing liquid used for polishing needs to have a pH in the range of 2.5 to 4.5. The pH is more preferably in the range of 2.5 to 4.0, and more preferably in the range of 3.0 to 4.0. Within this range, the polishing liquid of the present invention exhibits an excellent effect in terms of improving the polishing rate of the insulating film.
In order to adjust the pH of the polishing liquid of the present invention to a preferable range, an alkali agent or a buffering agent described later is used, and as the pH adjusting agent, an inorganic acid such as nitric acid, sulfuric acid, phosphoric acid, or the like is used. it can.

(Alkaline agent and buffer)
The polishing liquid of the present invention can contain an alkaline agent for adjusting the pH within the above-defined range of the present invention, and further a buffering agent from the viewpoint of suppressing fluctuations in pH, if necessary.
Alkaline agents (or buffering agents) include organic ammonium hydroxides such as ammonium hydroxide and tetramethylammonium hydroxide, non-metallic alkaline agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, carbonate, phosphate, borate, tetraborate, glycyl salt, N, N-dimethylglycine salt, leucine salt, norleucine Salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt, lysine salt Etc. can be used.

Specific examples of the alkali agent (or buffer) include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, phosphorus Examples thereof include disodium acid, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, ammonium hydroxide, and tetramethylammonium hydroxide.
Particularly preferred alkali agents include ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkaline agent or inorganic acid may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of a polishing liquid used for polishing. More preferably, it is 0.003 mol to 0.5 mol.

(Chelating agent)
The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening agent) as necessary in order to reduce adverse effects such as mixed polyvalent metal ions.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid. , Ethylenediamine-N, N, N ′, N′-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid ( SS form), N- (2-carboxylateethyl) -L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N , N′-bis (2-hydroxyben Le) ethylenediamine -N, N'-diacetic acid, and the like.

  Two or more chelating agents may be used in combination as required. The addition amount of the chelating agent may be an amount sufficient to sequester metal ions such as mixed polyvalent metal ions, for example, 0.0003 mol to 0.07 mol in 1 L of a polishing liquid used for polishing. Add to be.

(Other additives)
Further, the following additives can be used in the polishing liquid of the present invention.
Ammonia; alkylamines such as dimethylamine, trimethylamine, triethylamine and propylenediamine; amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan; dithizone, cuproin (2,2'-biquinoline), neocuproin (2, Imines such as 9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazone (biscyclohexanone oxalyl hydrazone); benzimidazole-2-thiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyric acid, 2-mercaptobenzothiazole, 1,2,3-triazole, 1,2,4- Azoles such as triazole and 3-amino-1H-1,2,4-triazole; mercaptans such as nonyl mercaptan, dodecyl mercaptan, triazine thiol, triazine dithiol, triazine trithiol, others, anthranilic acid, aminotoluic acid, quinaldic acid, L-tryptophan etc. are mentioned. Among these, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, and triazinedithiol are particularly preferable for achieving both a high CMP rate and a low etching rate.

  The additive amount of these additives is preferably 0.0001 mol to 0.5 mol, more preferably 0.001 mol to 0.2 mol, and more preferably 0.005 mol to 0.2 mol in 1 L of a polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the addition amount of the additive is preferably 0.0001 mol or more from the viewpoint of suppressing etching, and preferably 0.5 mol or less from the viewpoint of preventing a decrease in CMP rate.

(Dispersion medium)
As a dispersion medium for polishing liquid that can be used in the present invention, water alone or water as a main component (in the dispersion medium, 50 to 99% by mass), and a water-soluble organic solvent such as alcohol or glycol as a subcomponent (1 (About 30% by mass) can be used.
The water is preferably pure water or ion-exchanged water that does not contain macro particles as much as possible.
Examples of the alcohol include methyl alcohol, ethyl alcohol, and isopropyl alcohol, and examples of the glycol include ethylene glycol, tetramethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol.
The content of the dispersion medium in the polishing liquid is preferably 75 to 95% by mass, and more preferably 85 to 90% by mass. 75 mass% or more is preferable from a viewpoint of the supply property to the board | substrate of polishing liquid.

  The polishing liquid according to the present invention has, due to the adsorptivity and reactivity to the polishing surface, the solubility of the polishing metal, the electrochemical properties of the surface to be polished, the dissociation state of the compound functional group, the stability as the liquid, etc. It is preferable to set the compound species, addition amount, pH, and dispersion medium in a timely manner.

  In the present invention, among the components added at the time of preparing the concentrate of the polishing liquid, the blending amount of water having a solubility in water at room temperature of less than 5% prevents precipitation when the concentrate is cooled to 5 ° C. Thus, it is preferably within 2 times the solubility in water at room temperature, and more preferably within 1.5 times.

[Polished object]
The polishing liquid of the present invention generally exists between a metal wiring made of copper and / or a copper alloy and an interlayer insulating film, and forms a barrier metal layer for preventing diffusion of copper and / or a copper alloy. Suitable for polishing metal materials.
Hereinafter, an object to be polished which performs CMP by applying the polishing liquid of the present invention will be described.

[Barrier metal material]
In the present invention, the barrier metal material constituting the barrier metal layer of the object to be polished (target to be polished) is generally preferably a low-resistance metal material, and in particular, tantalum (Ta), tantalum nitride (TaN), titanium (Ti). , Titanium nitride (TiN), tungsten (W), tungsten nitride (WN), nickel (Ni), nickel nitride (NiN), ruthenium (Ru), ruthenium nitride (RuN), and titanium-tungsten alloy (Ti-W) It is preferable that at least one selected from the group consisting of:
Among these, TiN, Ti-W, Ta, TaN, W, and WN are preferable, and Ta and TaN are particularly preferable.

  The polishing liquid of the present invention can be suitably used for polishing a barrier metal layer in a semiconductor such as LSI. However, when polishing the barrier layer, the metal wiring can also be suitably polished at the same time. According to the polishing liquid of the invention, the metal wiring can also be suitably polished. In addition to the polishing of barrier metal materials and metal wiring, the substrate material such as silicon substrate, silicon oxide, silicon nitride, resin, or insulating film material is partially polished by the effect of acid, abrasive grains, etc. In some cases, a part of the carbon wiring formed incidentally is polished.

[Wiring metal materials]
With the polishing liquid of the present invention, the metal material constituting the metal wiring of the object to be polished (target to be polished) can also be suitably polished. The metal wiring is preferably a wiring made of copper metal and / or a copper alloy in a semiconductor such as LSI, for example, and particularly preferably a copper alloy. Furthermore, it is preferable that it is a copper alloy containing silver among copper alloys. The silver content contained in the copper alloy is preferably 40% by mass or less, particularly 10% by mass or less, more preferably 1% by mass or less, and most preferably in the range of 0.00001 to 0.1% by mass. Exhibits excellent effects.

(Wiring thickness)
The semiconductor to which the polishing method of the present invention can be applied is, for example, an LSI having a wiring of 0.15 μm or less at a half pitch in a DRAM device system, more preferably 0.10 μm or less, and 0.08 μm. More preferably, it is as follows. On the other hand, in the MPU device system, an LSI having a wiring of 0.12 μm or less is preferable, 0.09 μm or less is more preferable, and 0.07 μm or less is more preferable. The polishing liquid of the present invention exhibits an excellent effect on these DRAMs or LSIs.

(Wafer)
The polishing liquid of the present invention is suitably used even for large-area wafers because erosion during polishing is suitably suppressed. From such a viewpoint, a wafer as an object to be polished has a diameter of 200 mm. It is preferable that it is above, and 300 mm or more is particularly preferable. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

[Polishing method]
A polishing method to which the polishing liquid of the present invention can be applied will be described.
While supplying the polishing liquid mainly for polishing the barrier metal material of the present invention to the polishing pad on the polishing surface plate, the polishing pad is brought into contact with the polishing surface of the object to be polished, for example, to be polished. As a body, a wafer (semiconductor substrate) on which a conductive material film (for example, a metal layer) is formed is chemically and mechanically planarized.
The polishing liquid of the present invention is 1. 1. A concentrated liquid which is diluted by adding water or an aqueous solution when used. 2. When each component is prepared in the form of an aqueous solution described in the next section, these are mixed, and if necessary diluted with water to make a working solution. It may be prepared as a working solution.
In the case of polishing using the polishing liquid of the present invention, any of the above cases can be applied by appropriately selecting the mode depending on the purpose or depending on the composition and stability of the polishing liquid.

As an apparatus used for polishing, a holder for holding a semiconductor substrate (wafer) having a surface to be polished, a polishing surface plate to which a polishing pad is attached (a motor or the like whose rotation speed can be changed is attached), A general polishing apparatus having the following can be used.
As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation.
The polishing conditions are not limited, but the rotation speed of the polishing platen is preferably a low rotation of 200 rpm or less so that the substrate does not jump out. The pressure applied to the polishing pad of the substrate for a semiconductor integrated circuit having a surface to be polished (film to be polished) is preferably 5 to 500 g / cm ² (0.68 to 34.5 kPa). In order to satisfy body (wafer) in-plane uniformity and pattern flatness, it is more preferably 12 to 240 g / cm ² (3.40 to 20.7 kPa).

During polishing, a polishing liquid is continuously supplied to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid.
In the polishing method using the polishing liquid of the present invention, the flow rate of the polishing liquid (polishing liquid flow rate) per minute supplied to the object to be polished is the flow rate relative to the area of the object to be polished (substrate wafer area). However, it is preferable that the polishing liquid flow rate per minute supplied to the object to be polished during the polishing process is 0.2 to 1.2 ml / (min · cm ² ). From the viewpoint of not raising the processing temperature too much, it is more preferably 0.4 to 1.0 ml / (min · cm ² ). When the polishing liquid flow rate is in this range, it is preferable because the processing temperature is appropriately maintained, a sufficient polishing rate is achieved, and erosion can be suppressed.

In the present invention, the 1. When diluting the concentrate as in the above method, the aqueous solution used for diluting is water containing at least one of an oxidizing agent, an organic acid, an additive, and a surfactant in advance. It is preferable to use what was adjusted so that the component which contained the component contained and the component of the polishing liquid diluted could become the component of the polishing liquid (use liquid) used when grind | polishing using a polishing liquid.
Thus, when the concentrate is diluted with an aqueous solution and used, components that are difficult to dissolve can be added later in the form of an aqueous solution, so that a more concentrated concentrate can be prepared.

  In addition, as a method of diluting by adding water or an aqueous solution to the concentrated liquid, the pipe for supplying the concentrated polishing liquid and the pipe for supplying the water or the aqueous solution are joined together and mixed, and mixed and diluted. There is a method of supplying the used liquid to the polishing pad. Mixing of concentrated liquid with water or aqueous solution is a method in which liquids collide with each other through a narrow passage under pressure, filling the pipe with a filler such as a glass tube, and separating and separating the liquid flow. Ordinary methods such as a method of repeatedly performing and a method of providing a blade rotating with power in the pipe can be employed.

  Further, as a method of polishing while diluting the concentrated liquid with water or an aqueous solution, a pipe for supplying the polishing liquid and a pipe for supplying the water or the aqueous solution are provided independently, and a predetermined amount of liquid is respectively applied to the polishing pad. There is a method of supplying and polishing while mixing by the relative motion of the polishing pad and the surface to be polished. It is also possible to use a method in which a predetermined amount of concentrated liquid and water or an aqueous solution are mixed in one container and then the mixed polishing liquid is supplied to the polishing pad for polishing.

As another polishing method using the polishing liquid of the present invention, the components to be contained in the polishing liquid are divided into at least two components, and when these are used, they are diluted by adding water or an aqueous solution. There is a method of polishing by supplying the upper polishing pad and bringing the surface to be polished into contact with the surface to be polished and moving the surface to be polished and the polishing pad relatively.
For example, an oxidant is used as the component (A), an organic acid, an additive, a surfactant, and water are used as the component (B). A component (B) can be diluted and used.
Further, an additive having low solubility is divided into two constituent components (A) and (B). For example, an oxidizing agent, an additive, and a surfactant are used as the constituent component (A), and an organic acid, an additive, and a surface active agent are used. An agent and water are used as the component (B), and when they are used, water or an aqueous solution is added to dilute the component (A) and the component (B).

In the case of the above example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing supplies the three pipes to the polishing pad. There is a method of connecting to one pipe and mixing in the pipe. In this case, it is possible to connect two pipes and then connect another pipe. Specifically, this is a method in which a constituent component containing an additive that is difficult to dissolve is mixed with another constituent component, a mixing path is lengthened to ensure a dissolution time, and then a water or aqueous solution pipe is further coupled. .
As described above, the other mixing methods are as follows. The three pipes are directly guided to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, or the three components are mixed in one container. There is a method of supplying diluted polishing liquid to the polishing pad from there.

  In the above polishing method, when one constituent component containing an oxidizing agent is made 40 ° C. or lower and the other constituent components are heated in the range of room temperature to 100 ° C., one constituent component and another constituent component are mixed. Alternatively, when diluting by adding water or an aqueous solution, the liquid temperature can be set to 40 ° C. or lower. This method is a preferable method for increasing the solubility of the raw material having a low solubility of the polishing liquid by utilizing the phenomenon that the solubility becomes high when the temperature is high.

  The raw materials in which the above other components are dissolved by heating in the range of room temperature to 100 ° C. are precipitated in the solution when the temperature is lowered. It is necessary to dissolve the raw material deposited by heating. For this purpose, there are provided means for heating and feeding the other constituents in which the raw material is dissolved, and means for stirring and feeding the liquid containing the precipitate, and heating and dissolving the piping. Can be adopted. When the temperature of one constituent component containing an oxidizing agent is increased to 40 ° C. or higher, the other constituent components that have been heated may be decomposed. When two components are mixed, it is preferable that the temperature be 40 ° C. or lower.

  Thus, in the present invention, the components of the polishing liquid may be divided into two or more parts and supplied to the polishing surface. In this case, it is preferable to divide and supply the component containing an oxide and the component containing an organic acid. Alternatively, the polishing liquid may be a concentrated liquid, and diluted water may be separately supplied to the polishing surface.

(Polishing pad)
The polishing pad for polishing may be a non-foamed structure pad or a foamed structure pad. The former uses a hard synthetic resin bulk material like a plastic plate for a pad. Further, the latter further includes three types of a closed foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminated system), and a two-layer composite (laminated system) is particularly preferable. Foaming may be uniform or non-uniform.
Further, it may contain abrasive grains (for example, ceria, silica, alumina, resin, etc.) used for polishing. In addition, the hardness may be either soft or hard, and either may be used. In the laminated system, it is preferable to use a different hardness for each layer. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate or the like. In addition, the surface contacting the polishing surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

(Polishing equipment)
An apparatus capable of performing polishing using the polishing liquid of the present invention is not particularly limited, but is mira mesa CMP, reflexion CMP (Applied Materials), FREX200, FREX300 (Ebara Seisakusho), NPS3301, NPS2301 (Nikon), A-FP -310A, A-FP-210A (Tokyo Seimitsu), 2300 TERES (Ram Research), Momentum (Speedfam IPEC), etc. can be mentioned.

Post-processing after polishing and planarization under such conditions will be described.
It is preferable that the semiconductor substrate (object to be polished) after the polishing is cleaned to remove polishing debris and remaining abrasive grains. Examples of the washing method include a method of washing well in running water, and washing with a washing solution containing a surfactant or the like is also possible in order to effectively remove the remaining components.
As a drying method after washing, a method of drying after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like can be used.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
<Example 1>
The polishing liquid shown below was prepared and evaluated for polishing.
[Preparation of polishing liquid]
The composition of the following polishing liquid 1 was mixed to prepare the polishing liquid of Example 1.
[Polishing liquid 1]
Colloidal silica particles (B-1, particle size: 25 nm: PL2 slurry) 10% by mass
Colloidal silica particles (B-2, particle size: 20 nm: PL2L slurry) 10% by mass
Specific organic acid: A-1 (2-ethyl-2-hydroxymethylbutanoic acid) 10 g / L
Heterocyclic compound: BTA (benzotriazole) 1 g / L
・ Quaternary ammonium compound: Tetrabutylammonium nitrate (TBA additive) 1 g / L
・ 30% hydrogen peroxide 10ml / L
(Pure water is added and the total volume is 1000 mL)
pH (adjusted with aqueous ammonia and sulfuric acid) 3.5

[Evaluation of polishing liquid]
Using a device "LGP-612" manufactured by Lapmaster as a polishing device, polishing the film provided on each patterned wafer while supplying the polishing liquid adjusted as described above under the following conditions: The level difference at that time was measured.
(Polished object (base))
A TEOS (tetraethoxysilane) substrate is patterned by a photolithography process and a reactive ion etching process to form wiring grooves and connection holes having a width of 0.09 to 100 μm and a depth of 600 nm. Further, the thickness is measured by a sputtering method. After forming a 20 nm Ta film, and subsequently forming a 50 nm thick copper film by the sputtering method, an 8-inch wafer was used in which a total 1000 nm thick copper film was formed by the plating method.
(Polishing conditions)
Table rotation speed: 64 rpm
Head rotation speed: 65 rpm
Polishing pressure: 13.79 kPa
Polishing pad: Rodel Nitta Co., Ltd.
Politex Prima Polishing Pad
Polishing liquid supply rate: 200 ml / min (0.63 ml / (min · cm ² ))

1. Polishing Rate Evaluation The polishing rate was determined by measuring the film thickness of the insulating film before and after CMP using a film measuring device F-20 manufactured by Filmetrics and converting from the following formula.
TEOS (tetraethoxysilane) was used as the insulating film.
The polishing rate is converted from the film thickness before and after polishing and is derived from the following equation.
formula:
Polishing rate (Å / min)
= (Thickness of insulating film before polishing-Thickness of insulating film after polishing) / Polishing time Thus, the polishing rate of the insulating film was measured.

2. Erosion Evaluation A patterned wafer with Ta exposed as a barrier metal material exposed on the entire surface is polished for 60 seconds using the polishing liquid of the present invention, and the erosion of the line and space portion (line 9 μm, space 1 μm) Measurement was performed using a step gauge Dektak V320Si (Veeco).

<Examples 2-24, Comparative Examples 1-2>
The polishing liquids of Examples 2 to 24 and Comparative Examples 1 and 2 were similarly prepared except that the composition of the polishing liquid 1 was changed to the components shown in Tables 1 and 2.
These polishing liquids were subjected to a polishing test under the same polishing conditions as in Example 1 and evaluated in the same manner as in Example 1.
The results are shown in Tables 1 and 2.

  The details of the specific organic acid (a) used in the examples are shown in Table 3 below.

  Details of (b) colloidal silica particles used in Examples and Comparative Examples are shown in Table 4 below.

The heterocyclic compounds (c) used in Examples and Comparative Examples are as shown below.
BTA = 1,2,3-benzotriazole DBTA = 5,6-dimethyl-1,2,3-benzotriazole DCEBTA = 1- (1,2-dicarboxyethyl) benzotriazole HEABTA = 1- [N, N- Bis (hydroxyethyl) aminomethyl] benzotriazole HMBTA = 1- (hydroxymethyl) benzotriazole

The (d) quaternary ammonium compound used as an additive is as follows.
TBA additive = tetrabutylammonium nitrate TMA additive = tetramethylammonium nitrate TEA additive = tetraethylammonium nitrate TPA additive = tetrapropylammonium nitrate TPNA additive = tetrapentylammonium nitrate LTM additive = lauryltrimethylammonium nitrate LTE additive = Lauryltriethylammonium nitrate DBS represents (e) dodecylbenzenesulfonate which is an anionic surfactant.

From the results of Tables 1 and 2, it can be seen that when the polishing liquid of the present invention is used, erosion is suitably suppressed while maintaining a sufficient polishing rate when the barrier metal material is polished.
On the other hand, it can be seen that the polishing liquids of Comparative Examples 1 and 2 that do not contain the specific organic acid of the present invention and have a high pH are inferior in erosion compared to the Examples.

Claims (9)

In a chemical mechanical planarization method of a semiconductor device in which a polishing liquid is supplied to a polishing pad on a polishing surface plate, and the polishing pad is brought into contact with a surface to be polished and moved relative to the polishing pad. A polishing liquid used for
(A) A polishing liquid containing a compound having a hydroxyl group and a carboxyl group in the molecule, (b) colloidal silica particles, and (c) a heterocyclic compound, and having a pH in the range of 2.5 to 4.5. . The polishing liquid according to claim 1, wherein the compound (a) having a hydroxyl group and a carboxyl group in the molecule is a compound represented by the following general formula (I).

In the general formula (I), R ^{1 to} R ³ each independently represent a hydrogen atom, a hydroxyl group, a hydroxyalkyl group or an alkyl group, R ⁴ represents a single bond or an alkylene group, and at least ^one of R ^{1 to} R ⁴ One is a hydroxyl group or a hydroxyalkyl group, or has a hydroxyl group or a hydroxyalkyl group as a substituent.   The compound represented by (a) general formula (I) is 2-hydroxypropanoic acid, 2-hydroxymethylpropanoic acid, 2-hydroxybutanoic acid, 2-hydroxy-2-methylpropanoic acid, 2-hydroxy-2. -Methylbutanoic acid, 2-hydroxymethyl-2-methylbutanoic acid, 3-hydroxy-2-methylpropanoic acid, 3-hydroxy-2,2-dimethylpropanoic acid, 2-hydroxymethyl-2-methylbutanoic acid, and 2-ethyl The polishing liquid according to claim 2, which is a compound selected from the group consisting of 2-hydroxymethylbutanoic acid.   The polishing liquid according to any one of claims 1 to 3, wherein the colloidal silica particles (b) are contained in an amount of 0.5% by mass to 15% by mass.   The polishing liquid according to any one of claims 1 to 3, wherein the (b) colloidal silica particles contain two or more kinds of colloidal particles having different particle sizes or shapes.   The polishing liquid according to any one of claims 1 to 3, wherein the average particle diameter of the (b) colloidal silica particles is in a range of 20 to 50 nm.   The (c) heterocyclic compound is a 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [ The compound according to any one of claims 1 to 6, which is one or more compounds selected from N, N-bis (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole. The polishing liquid as described.   Furthermore, (d) Quaternary alkyl ammonium compound is contained, The polishing liquid of any one of Claim 1 thru | or 7 characterized by the above-mentioned.   The polishing liquid according to any one of claims 1 to 8, further comprising (e) an anionic surfactant.