JP5524385B2 - Polishing liquid - Google Patents

Description

  The present invention relates to a polishing liquid used in a semiconductor device manufacturing process, and more particularly to a polishing liquid used for chemical mechanical polishing in planarization in a wiring process of a semiconductor device.

  In the development of a semiconductor device represented by a semiconductor integrated circuit (hereinafter referred to as LSI), in recent years, in order to reduce the size and increase the speed, there has been a demand for higher density and higher integration by miniaturizing and stacking wiring. 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 surface flattening of processed films such as interlayer insulation films, plug formation, formation of embedded metal wiring, etc., and smoothing of the substrate and removal of excess metal thin film during wiring formation In addition, an 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 substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction.
When manufacturing semiconductor devices such as LSI, fine wiring is formed in multiple layers, and when forming metal wiring such as Cu in each layer, diffusion of wiring material to the interlayer insulating film In order to prevent this and to improve the adhesion of the wiring material, a barrier metal such as Ta, TaN, Ti, or TiN is formed in advance.

In order to form each wiring layer, first, CMP of a metal film (hereinafter referred to as metal film CMP) for removing excess wiring material stacked by plating or the like is performed in one or more stages. Next, CMP (hereinafter referred to as barrier metal CMP) for removing the barrier metal material (barrier metal) exposed on the surface by this is generally performed. However, there is a problem that the metal film CMP causes so-called dishing in which the wiring portion is excessively polished and further causes erosion.
To reduce this dishing, the barrier metal CMP performed after the metal film CMP adjusts the polishing speed of the metal wiring portion and the polishing speed of the barrier metal portion, and finally the wiring having few steps such as dishing and erosion. There is a need to form a layer. 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. Therefore, it is desirable that the polishing rate of the barrier metal or the insulating film layer is appropriately high. This has the advantage of increasing the throughput of barrier metal CMP, and in fact, dishing is often caused by metal film CMP, and relative polishing rates of barrier metal and insulating film layers are relatively high for the reasons described above. This is also desirable in that it is required to be higher.

The metal polishing solution used for CMP generally contains abrasive grains (for example, alumina and silica) and an oxidizing agent (for example, hydrogen peroxide and persulfuric acid). It is considered that the basic mechanism is polishing by oxidizing the metal surface with an oxidizing agent and removing the oxide film with abrasive grains.
However, when CMP is performed using a polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and a part of the polished metal surface is overpolished. Phenomenon that the surface is dished (dishing), the insulator between the metal wires is polished more than necessary, and only the central part of the metal surfaces of the wiring is deeply polished, and the surface is dented (erosion) ) May occur.
Moreover, the use of a polishing liquid containing solid abrasive grains complicates the cleaning process normally performed to remove the polishing liquid remaining on the semiconductor surface after polishing, and further, the cleaning liquid (waste liquid) is removed. In order to process, there exists a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.

The following various studies have been made on the polishing liquid containing such solid abrasive grains.
For example, a CMP polishing agent and a polishing method (for example, refer to Patent Document 1) aiming at high-speed polishing with almost no polishing scratches generated, a polishing composition and a polishing method with improved cleaning performance in CMP (for example, , And Patent Document 2) and a polishing composition (see, for example, Patent Document 3) that prevents aggregation of abrasive grains have been proposed.
However, even with the above-described polishing liquid, a technique that can achieve a high polishing rate when polishing a necessary layer and suppress scratches caused by agglomeration of solid abrasive grains has not yet been obtained. The current situation is not.
In particular, in recent years, with the further miniaturization of wiring, a material having a lower dielectric constant, such as TEOS, having a lower dielectric constant than that of a commonly used interlayer insulating film has been used as the insulating film. These insulating films are referred to as low-k films, and for example, there are materials made of organic polymer, SiOC, SiOF, etc., and these are generally used by being laminated with an insulating film. Since the strength is lower than that of the film, the above problems of overpolishing and scratching become more prominent in CMP processing.

JP 2003-17444 A JP 2003-142435 A JP 2000-84832 A

  An object of the present invention is a polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit, wherein a normal TEOS insulating film and a low dielectric constant low-k film are formed. In a substrate having a laminated insulating film, an excellent polishing rate for a TEOS insulating film can be obtained. Even when a low-strength insulating film such as a Low-k film is used, the polishing rate for a Low-k film is effective. It is another object of the present invention to provide a polishing liquid capable of improving the resistance to scratches and suppressing scratches caused by aggregation of solid abrasive grains.

  As a result of intensive studies, the present inventor has found that the above problem can be solved by using the following polishing liquid, and has achieved the object. That is, the present invention

<1>
A polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit, and used for polishing a substrate having an insulating film in which a TEOS insulating film and a low-k film are stacked. And
A polishing liquid comprising a quaternary ammonium cation, a corrosion inhibitor, a polymer having a sulfone group or a salt structure thereof, inorganic particles, and an organic acid, and having a pH of 1 to 7.

<2>
Polymers having a sulfone group or a salt structure thereof at the terminal are P-1 to P-21 described later (n and m are each independently an integer of 2 to 10, x and y are x + y and an integer of 2 to 10, R Represents an alkyl group having 1 to 12 carbon atoms.) The polishing liquid according to <1>, wherein the polishing liquid is at least one selected from the group consisting of
<3>
The polymer having a sulfone group or a salt structure thereof at the terminal is at least one selected from P-1, P-3 to P-4, and P-6 to P-21. 2>.
<4>
The polishing liquid according to any one of <1> to <3>, wherein the quaternary ammonium cation is a cation represented by the following general formula (1) or general formula (2).
<5>
<4> The polishing liquid according to <4>, wherein the quaternary ammonium cation is a cation represented by the general formula (2).

[In General Formula (1) and General Formula (2), R ^{1 to} R ⁶ each independently represents an alkyl group, alkenyl group, cycloalkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms; Two of ^{1 to} R ⁶ may be bonded to each other to form a cyclic structure. X represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining two or more thereof. ]

<6>
The polishing liquid according to any one of <1> to <5>, wherein the inorganic particles are at least one inorganic particle selected from silica, alumina, ceria, zirconia, and titania.

<7>
The polishing liquid according to any one of <1> to <6>, wherein the concentration of the inorganic particles is 0.5 to 15% by mass with respect to the total mass of the polishing liquid.

<8>
The semiconductor integrated circuit has a barrier layer, and the material constituting the barrier layer is at least one of Ta, TaN, Ti, TiN, Ru, CuMn, MnO ₂ , WN, W, and Co. The polishing liquid according to any one of <1> to <7>, wherein:
<9>
<1> to <8> The polishing liquid according to any one of <8> is supplied to a polishing pad on a polishing surface plate and brought into contact with the surface to be polished of the object to be polished so that the surface to be polished and the polishing pad move relative to each other. And a chemical mechanical polishing method characterized by comprising polishing.

  According to the present invention, a polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit, wherein a normal TEOS insulating film and a low dielectric constant low-k film are formed. In a substrate having a laminated insulating film, an excellent polishing rate for a TEOS insulating film can be obtained. Even when a low-strength insulating film such as a Low-k film is used, the polishing rate for a Low-k film is effective. In addition, it is possible to provide a polishing liquid that can improve the resistance to scratches due to aggregation of solid abrasive grains.

Hereinafter, specific embodiments of the present invention will be described.
The polishing liquid of the present invention comprises a quaternary ammonium cation, a corrosion inhibitor, a polymer having a sulfone group or a salt structure at its terminal, inorganic particles, and an organic acid, and has a pH of 1 to 7, Any component may be included as necessary.
Each component contained in the polishing liquid of the present invention may be used alone or in combination of two or more.

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.
Hereinafter, each component which comprises the polishing liquid of this invention is demonstrated in detail.

[(A) Quaternary ammonium cation]
The polishing liquid of the present invention contains a quaternary ammonium cation (hereinafter sometimes simply referred to as “specific cation”).
The quaternary ammonium cation in the present invention is not particularly limited as long as it has a structure containing one or two quaternary nitrogens in the molecular structure. Especially, it is preferable that it is a cation represented by following General formula (1) or General formula (2) from a viewpoint of achieving the improvement of sufficient polishing rate.

In the general formula (1) and general formula (2), R ^{1 to} R ⁶ each independently represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, Two of R ^{1 to} R ⁶ may be bonded to each other to form a cyclic structure.

Specific examples of the alkyl group having 1 to 20 carbon atoms as R ^{1 to} R ⁶ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Of these, a methyl group, an ethyl group, a propyl group, and a butyl group are preferable.
Moreover, as an alkenyl group as said R < ¹ > -R < ⁶ >, a C2-C10 thing is preferable, and specifically, an ethynyl group, a propyl group, etc. are mentioned.

Specific examples of the cycloalkyl group as R ^{1 to} R ⁶ include a cyclohexyl group and a cyclopentyl group, and among them, a cyclohexyl group is preferable.
Specific examples of the aryl group as R ^{1 to} R ⁶ include a butynyl group, a pentynyl group, a hexynyl group, a phenyl group, and a naphthyl group, and among them, a phenyl group is preferable.
Specific examples of the aralkyl group as R ^{1 to} R ⁶ include a benzyl group, and among them, a benzyl group is preferable.

Each group represented by R ^{1 to} R ⁶ may further have a substituent. Examples of the substituent that can be introduced include a hydroxyl group, an amino group, a carboxyl group, a heterocyclic group, a pyridinium group, and an aminoalkyl. Group, phosphoric acid group, imino group, thiol group, sulfo group, nitro group and the like.

X in the general formula (2) represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining two or more of these groups.
In addition to the above organic linking group, the linking group represented by X includes —S—, —S (═O) ₂ —, —O—, —C (═O) — in the chain. May be included.

Specific examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, and an octylene group. Among them, an ethylene group, A pentylene group is preferred.
Specific examples of the alkenylene group include an ethynylene group and a propynylene group, and among them, a propynylene group is preferable.
Specific examples of the cycloalkylene group include a cyclohexylene group and a cyclopentylene group. Among them, a cyclohexylene group is preferable.
Specific examples of the arylene group include a phenylene group and a naphthylene group, and among them, a phenylene group is preferable.

  Each of the above linking groups may further have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, an amino group, a sulfonyl group, a carboxyl group, a heterocyclic group, a pyridinium group, an aminoalkyl group, and a phosphate group. , Imino group, thiol group, sulfo group, nitro group and the like.

  Hereinafter, although the specific example [Exemplary compound (A-1)-(A-46)] of (A) quaternary ammonium cation (specific cation) in this invention is shown, this invention is not limited to these.

Among the quaternary ammonium cations (specific cations) as described above, A8, A10, A11, A12, A36, A37, and A46 are preferable from the viewpoint of dispersion stability in the polishing liquid.

The (A) quaternary ammonium cation (specific cation) in the present invention can be synthesized, for example, by a substitution reaction in which ammonia or various amines serve as a nucleophile.
Moreover, the purchase as a general sale reagent is also possible.

  The amount of addition of (A) quaternary ammonium cation (specific cation) in the present invention is the polishing liquid used for polishing (that is, the diluted polishing liquid when diluted with water or an aqueous solution. "The polishing liquid when doing this" is also in agreement. That is, the addition amount of the specific cation is preferably 0.0001% by mass or more from the viewpoint of sufficiently improving the polishing rate, and is preferably 0.3% by mass or less from the viewpoint of sufficient slurry stability.

[(B) Corrosion inhibitor]
The polishing liquid of the present invention contains a corrosion inhibitor that adsorbs to the surface to be polished to form a film and controls the corrosion of the metal surface. As a corrosion inhibitor in this invention, it is preferable to contain the hetero aromatic ring compound which has a 3 or more nitrogen atom in a molecule | numerator, and has a condensed ring structure. Here, the “three or more nitrogen atoms” are preferably atoms constituting a condensed ring. As such a heteroaromatic ring compound, benzotriazole and various substituents are introduced into the benzotriazole. It is preferable that it is a derivative | guide_body which becomes.

  Corrosion inhibitors that can be used in the present invention include benzotriazole, 1,2,3-benzotriazole, 5,4-dimethyl-1,2,3-benzotriazole, and 1- (1,2-dicarboxyethyl) benzo. Triazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole, 1- (hydroxymethyl) benzotriazole, (B) the corrosion inhibitor is 1,2,3-benzotriazole, 5,4 -Dimethyl-1,2,3-benzotriazole, tolyltriazole, 1- (1,2-dicarboxyethyl) tolyltriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] tolyltriazole, 1- ( 2,3-dihydroxypropyl) benzotriazole, 1- (2,3-dihydroxypropyl) tolyltriazo And a compound selected from the group consisting of 1- (hydroxymethyl) benzotriazole, among others, 1,2,3-benzotriazole, 5,4-dimethyl-1,2,3-benzotriazole, Tolyltriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- (1,2-dicarboxyethyl) tolyltriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole, 1 -[N, N-bis (hydroxyethyl) aminomethyl] tolyltriazole, 1- (2,3-dihydroxypropyl) benzotriazole, 1- (2,3-dihydroxypropyl) tolyltriazole, and 1- (hydroxymethyl) More preferably, it is selected from benzotriazole.

  The amount of the (B) corrosion inhibitor added is preferably 0.01% by mass or more and 0.2% by mass or less, and more preferably 0.05% by mass or more and 0% by mass with respect to the mass of the polishing liquid used for polishing. More preferably, it is 2% by mass or less. That is, the addition amount of such a corrosion inhibitor is preferably 0.01% by mass or more from the viewpoint of not expanding dishing, and is preferably 0.2% by mass or less from the viewpoint of storage stability.

[(C)] Polymer having a sulfone group at the terminal The polishing liquid of the present invention contains a polymer having a sulfone group at the terminal.
In the polishing liquid of the present invention, the polishing rate can be improved and the polishing rate of the insulating layer can be controlled by adjusting the type and amount of the polymer having a sulfone group at the terminal to be used.

  Examples of the structure of the polymer having a sulfone group at the terminal include polyoxyethylene lauryl ether sulfate, polyoxyethylene phenyl ether sulfate, polyoxyethylene lauryl ether sulfate, polyoxyethylene tridecyl phenyl ether sulfate, Examples thereof include oxypropylene lauryl ether sulfate, polyoxyethylene capryl ether sulfate, polyoxyethylene capryl phenyl ether sulfate, polyoxyethylene pentadecyl phenyl ether sulfate, and butyl naphthalene sulfonate. Among these, a polymer having a benzene ring is preferable.

  Examples of the polymer having a benzene ring include polyoxyethylene phenyl ether sulfate, polyoxyethylene tridecyl phenyl ether sulfate, polyoxyethylene capryl phenyl ether sulfate, polyoxyethylene pentadecyl phenyl ether sulfate, and butyl naphthalene. Examples include sulfonates.

  In the polymer having a sulfone group at the terminal, the sulfone group may have a salt structure such as a sodium salt, a potassium salt, or an ammonium salt.

  The weight average molecular weight of the polymer having a sulfone group at the terminal is preferably 500 or more and 5000 or less, more preferably 600 or more and 4000 or less, and particularly preferably 600 or more and 3000 or less. That is, the weight average molecular weight of the polymer having a sulfone group at the terminal is preferably 500 or more from the viewpoint of SiOC polishing performance, and preferably 3000 or less from the viewpoint of scratch performance after polishing.

  Hereinafter, although the specific example [Exemplary compound (P-1)-(P-21)] of the polymer which has a sulfone group in the (C) terminal in this invention is shown, this invention is not limited to these. However, in specific examples, n and m are integers of 2 to 10, and x and y are x + y and represent an integer of 2 to 10. R represents an alkyl group having 1 to 12 carbon atoms.

  (C) The addition amount of the polymer having a sulfone group at the terminal is preferably 0.001 to 10 g, and preferably 0.01 to 5 g in 1 L of polishing liquid when used for polishing as a total amount. Is more preferable, and 0.01 to 1 g is particularly preferable. That is, such a polymer having a sulfone group at the terminal (C) is preferably 0.0001 g or more in 1 L of polishing liquid in terms of SiOC polishing performance, and 1 g or less in 1 L of polishing liquid from the viewpoint of foamability. Is preferred.

[(D) inorganic particles]
The polishing liquid of the present invention contains inorganic particles.
In the polishing liquid of the present invention, the inorganic particles to be used are those used as abrasive particles (solid abrasive grains), for example, silica (precipitated silica, fumed silica, colloidal silica, synthetic silica), alumina, ceria, zirconia, titania. , Germania, manganese oxide, silicon carbide, and the like. Among these, silica, alumina, ceria, zirconia, and titania are preferable. In particular, silica is preferable, and colloidal silica is more preferable.

  The colloidal silica is preferably colloidal silica that does not contain impurities such as alkali metals inside the particles and is obtained by hydrolysis of alkoxysilane. On the other hand, although colloidal silica produced by a method of removing alkali from an alkali silicate aqueous solution can also be used, in this case, there is a concern that the alkali metal remaining in the particles gradually elutes and affects the polishing performance. . From such a viewpoint, a material obtained by hydrolysis of alkoxysilane is more preferable as a raw material.

  The size of the inorganic particles is preferably 5 nm to 200 nm, more preferably 10 nm to 100 nm, and particularly preferably 20 nm to 70 nm.

  The content (concentration) of (D) inorganic particles in the polishing liquid of the present invention is preferably 0.5% by mass or more and 15% by mass or less with respect to the mass of the polishing liquid used for polishing. Preferably they are 3 mass% or more and 12 mass% or less, Especially preferably, they are 5 mass% or more and 12 mass% or less. That is, the content of (D) inorganic particles is preferably 0.5% by mass or more in terms of polishing the barrier layer at a sufficient polishing rate, and is preferably 15% by mass or less in terms of storage stability.

  Here, in the polishing liquid of the present invention, other inorganic particles can be used together with the colloidal silica among the (D) inorganic particles, but even in that case, the content ratio of the colloidal silica in the inorganic particles Is preferably 50% by mass or more, and particularly preferably 80% by mass or more. All of the contained abrasive grains may be colloidal silica. Examples of abrasive grains that can be used in combination with colloidal silica for the polishing liquid of the present invention include fumed silica, ceria, alumina, and titania. The size of these combination abrasive grains is preferably equal to or more than that of colloidal silica, and is preferably twice or less.

[(E)] Organic acid The polishing liquid of the present invention contains an organic acid.
Examples of organic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n -Heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, Examples thereof include maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, and salts such as ammonium salt and alkali metal salt thereof, sulfuric acid, nitric acid, ammonia, ammonium salts, and mixtures thereof. Of these, compounds having a carboxyl group are preferred.

The compound having a carboxyl group is not particularly limited as long as it is a compound having at least one carboxyl group in the molecule, but a compound represented by the following general formula (3) is selected from the viewpoint of the polishing rate structure. Is preferred.
In addition, it is preferable that the number of the carboxyl groups which exist in a molecule | numerator is 1-4, and it is more preferable that it is 1-2 from a viewpoint which can be used cheaply.

In the general formula (3), R ⁷ and R ⁸ each independently represent a hydrocarbon group, preferably a C 1-10 hydrocarbon group.
R ⁷ is a monovalent hydrocarbon group, for example, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, a cycloalkyl group, etc.), an aryl group (for example, a phenyl group), an alkoxy group, an aryloxy group Groups and the like are preferred.
R ⁸ is a divalent hydrocarbon group, for example, an alkylene group having 1 to 10 carbon atoms (for example, a methylene group or a cycloalkylene group), an arylene group (for example, a phenylene group), an alkyleneoxy group, or the like. preferable.
The hydrocarbon group represented by R ⁷ and R ⁸ may further have a substituent. Examples of the substituent that can be introduced include an alkyl group having 1 to 3 carbon atoms, an aryl group, an alkoxy group, and a carboxyl group. Group, etc., and when it has a carboxyl group as a substituent, this compound has a plurality of carboxyl groups.
R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure.

  Examples of the compound represented by the general formula (3) include 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid, and methoxyphenyl. Acetic acid, phenoxyacetic acid and the like can be mentioned. Among them, 2,5-furandicarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid and methoxyacetic acid are preferable from the viewpoint of polishing the surface to be polished at high speed.

  In the polishing liquid of the present invention, the addition amount of (E) an organic acid (preferably a compound having a carboxyl group: a compound represented by the general formula (3)) is based on the mass of the polishing liquid used for polishing. 0.1 mass% or more and 5 mass% or less are preferable, and 0.5 mass% or more and 2 mass% or less are still more preferable. That is, the content of such an organic acid is preferably 0.1% by mass or more from the viewpoint of achieving a sufficient polishing rate, and is preferably 5% by mass or less from the point of not causing excessive dishing.

[Other ingredients]
In the polishing liquid of the present invention, in addition to the essential components (A) to (E), other known components can be used in combination as long as the effects of the present invention are not impaired.

[Surfactant]
In the polishing liquid of the present invention, a surfactant other than the nonionic surfactant can be used in combination. Examples of the surfactant that can be used in combination include an anionic surfactant and a cationic surfactant.

  Specific examples of the anionic surfactant include compounds such as decylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, dodecylnaphthalenesulfonic acid, and tetradecylnaphthalenesulfonic acid. Can be mentioned.

  Specific examples of the cationic surfactant include compounds such as lauryltrimethylammonium, lauryltriethylammonium, stearyltrimethylammonium, palmityltrimethylammonium, octyltrimethylammonium, dodecylpyridinium, decylpyridinium, octylpyridinium, and the like.

Preferred examples of the anionic surfactant that can be used in the present invention include carboxylic acid salts, sulfuric acid ester salts, and phosphoric acid ester salts in addition to the sulfonic acid salts.
More specifically, as the carboxylate, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxylate, acylated peptide;
As sulfate salts, sulfated oils, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates;
As the phosphate ester salt, an alkyl phosphate, polyoxyethylene or polyoxypropylene alkylallyl ether phosphate can be preferably used.

  The total amount of other surfactants that can be used in combination is preferably 0.001 to 10 g and more preferably 0.01 to 5 g in 1 L of a polishing liquid used for polishing. It is especially preferable to set it as 0.01-1g. That is, the addition amount of the surfactant is preferably 0.01 g or more for obtaining a sufficient effect, and preferably 1 g or less from the viewpoint of preventing the CMP rate from being lowered.

(Oxidant)
The polishing liquid of the present invention can contain a compound (oxidant) capable of oxidizing the 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. Among them, hydrogen peroxide is preferably used.
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 CMP. When the amount of dishing at the beginning of barrier CMP is large, that is, when it is not desired to polish the wiring material very much in barrier CMP, it is desirable to add a small amount of oxidizer, the dishing amount is sufficiently small, and the wiring material can be removed at high speed. When polishing is desired, it is desirable to increase the addition amount of the oxidizing agent. Thus, since it is desirable to change the addition amount of the oxidizing agent depending on the dishing situation at the initial stage of the barrier CMP, it is preferable that the amount is 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. It is especially preferable to set it as 05 mol-0.4 mol.

(PH adjuster)
The polishing liquid of the present invention needs to have a pH of 2.5 to 5.0 and is preferably in the range of pH 3.0 to 4.5. By controlling the pH of the polishing liquid within this range, the polishing rate of the interlayer insulating film can be adjusted more significantly.
In order to adjust the pH to the above preferred range, an alkali / acid or a buffer is used. The polishing liquid of the present invention exhibits an excellent effect when the pH is within this range.
Examples of alkali / acid or buffering agents include non-metallic alkaline agents such as organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, alkanolamines such as diethanolamine, triethanolamine and triisopropanolamine. Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, inorganic acids such as nitric acid, sulfuric acid and phosphoric acid, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, boric acid Preferable examples include salts, tetraborate and hydroxybenzoate. Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  As the addition amount of the alkali / acid or the buffer, it is sufficient that the pH is maintained in a preferable range as long as it is equal to or less than the above-described electric conductivity value. In 1 L of the polishing liquid used for polishing, It is preferable to set it as 0.0001 mol-1.0 mol, and it is more preferable to set it as 0.003 mol-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, 1,2-dihydroxybenzene-4,4-disulfonic acid and the like.

Two or more chelating agents may be used in combination as necessary.
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.

  The polishing liquid of the present invention is generally suitable for polishing a barrier layer made of a barrier metal material for preventing diffusion of copper, which exists between a wiring made of copper metal and / or a copper alloy and an interlayer insulating film.

[Barrier metal material]
The material constituting the barrier layer to be polished by the polishing liquid of the present invention is generally a low-resistance metal material, and in particular, Ta, TaN, Ti, TiN, Ru, CuMn, MnO ₂ , WN, W, and Co Of these, at least one is preferable, and Ta and TaN are particularly preferable.

[Interlayer insulation film]
As an interlayer insulating film (insulating layer) to be polished by the polishing liquid of the present invention, in addition to a commonly used interlayer insulating film such as TEOS, for example, a low dielectric constant having a relative dielectric constant of about 3.5 to 2.0 An interlayer insulating film including a material (for example, an organic polymer system, a SiOC system, a SiOF system, etc., and is generally abbreviated as a Low-k film) can be used.
Specifically, as a material used for forming a low dielectric constant interlayer insulating film, there are HSG-R7 (Hitachi Chemical Industries), BLACKDIAMOND (Applied Materials, Inc.) and the like in the SiOC system.
Such a Low-k film is usually located under the TEOS insulating film, and a barrier layer and a metal wiring are formed on the TEOS insulating film.
The polishing liquid of the present invention can polish the barrier layer suitably, and is applied to a substrate having a laminated structure of a low-k film and a TEOS insulating film, whereby the TEOS insulating film is polished at a high speed, and the low-k film is obtained. This is characterized in that the polishing rate is improved at the time when the surface is exposed, polishing having excellent surface smoothness and generation of scratches can be achieved.

[Raw metal materials]
In the present invention, it is preferable that the object to be polished has a wiring made of copper metal and / or copper alloy as applied to a semiconductor device such as LSI. In particular, a copper alloy is preferable as a raw material for the wiring. Furthermore, the copper alloy containing silver is preferable among copper alloys.
In addition, 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 a copper alloy in the range of 0.00001 to 0.1% by mass. The most excellent effect is exhibited.

[Wiring thickness]
In the present invention, when the object to be polished is applied to, for example, a DRAM device system, it preferably has a wiring with a half pitch of 0.15 μm or less, more preferably 0.10 μm or less, and further Preferably it is 0.08 micrometer or less.
On the other hand, when the object to be polished is applied to, for example, an MPU device system, it is preferable to have a wiring of 0.12 μm or less, more preferably 0.09 μm or less, and still more preferably 0.07 μm or less.
The polishing liquid in the present invention described above exhibits a particularly excellent effect on the object to be polished having such wiring.

[Polishing method]
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.
The polishing liquid in any case can be applied to the polishing method using the polishing liquid of the present invention.
This polishing method is a method in which a polishing liquid is supplied to a polishing pad on a polishing surface plate and brought into contact with a surface to be polished of an object to be polished so that the surface to be polished and the polishing pad move relative to each other.

  As an apparatus used for polishing, a holder for holding an object to be polished (for example, a wafer on which a conductive material film is formed) having a surface to be polished and a polishing pad are attached (a motor capable of changing the number of rotations). Etc.) and a general polishing apparatus having a polishing surface plate. 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 surface plate is preferably a low rotation of 200 rpm or less so that the object to be polished does not pop out. The pressing pressure of the object to be polished having the surface to be polished (film to be polished) against the polishing pad is preferably 0.48 to 34.5 KPa, and the in-plane uniformity of the object to be polished and the flatness of the pattern at the polishing rate are preferable. In order to satisfy the properties, it is more preferably 3.40 to 20.7 KPa.

During polishing, the polishing liquid is continuously supplied to the polishing pad with a pump or the like.
After the polishing is finished, the object to be polished is thoroughly washed in running water, and then dried after removing water droplets adhering to the object to be polished using a spin dryer or the like.

In the present invention, the 1. When diluting the concentrated solution as in the above method, the following aqueous solutions can be used. The aqueous solution is water containing at least one of an oxidizing agent, an organic acid, an additive, and a surfactant in advance, and the components contained in the aqueous solution and the concentrated solution to be diluted are contained. A component obtained by summing up the component and the component is used as a component of a polishing liquid (use liquid) used for polishing.
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.

  The supply rate of the polishing liquid is preferably 10 to 1000 ml / min, and more preferably 170 to 800 ml / min in order to satisfy the in-surface uniformity of the polishing rate and the flatness of the pattern.

  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.

In addition, as another polishing method, the component to be contained in the polishing liquid is divided into at least two components, and when these are used, water or an aqueous solution is added and diluted and supplied to the polishing pad on the polishing platen Then, there is a method in which the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished for polishing.
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 surface to be polished. 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 supplied to the surface to be polished separately from the dilution water.
In the present invention, in the present invention, when applying a method of dividing the polishing liquid components into two or more parts and supplying them to the surface to be polished, the supply amount represents the total supply amount from each pipe. It is.

〔pad〕
The polishing pad for polishing applicable to the polishing method of the present invention 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 inorganic particles generally used for polishing (abrasive grains: for example, ceria, silica, alumina, etc.). 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. As the material, non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate and the like are preferable. Further, the surface contacting the surface to be polished may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

[Wafer]
In the present invention, a wafer as an object to be subjected to CMP with the polishing liquid preferably has a diameter of 200 mm or more, particularly preferably 300 mm or more. The effect of the present invention is remarkably exhibited when the thickness is 300 mm or more.

[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.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to them.

[Example 1]
A polishing liquid having the composition shown below was prepared and a polishing experiment was conducted.
<Composition (1)>
(A) Quaternary ammonium cation: A1 0.2 g / L
(B) Corrosion inhibitor: benzotriazole (BTA) 0.5 g / L
(C) Polymer having a sulfone group at the terminal: P-1 0.1 g / L
(D) Inorganic particles: Colloidal silica: C-1 200 g / L
(Secondary particle size: 45 nm, PL3 slurry, manufactured by Fuso Chemical Industries)
(E) Organic acid: Compound having a carboxyl group: B-1 1 g / L
(Wako Pure Chemical Industries, Ltd.)
・ Oxidizing agent: Hydrogen peroxide 10ml
・ Pure water is added and the total volume is 1000mL
pH (adjusted with ammonia water and nitric acid) 3.5

(Evaluation method)
The apparatus “LGP-412” manufactured by Lapmaster Co., Ltd. was used as a polishing apparatus, and each wafer film shown below was polished while supplying slurry under the following conditions.
・ Table rotation speed: 90rpm
-Head rotation speed: 85rpm
Polishing pressure: 13.79 kPa
Polishing pad: Rotex Nitta Co., Ltd. Polotepad
Polishing liquid supply rate: 200 ml / min

(Polishing rate evaluation: polishing object)
As an object to be polished, an 8-inch wafer in which an SiOC film (BLACKDIAMMOND (Applied Materials, Inc), TEOS film, Ta film, and copper film) was sequentially formed on a Si substrate was used.

(Scratch evaluation: object to be polished)
As a polishing object, a low-k film and a TEOS film manufactured by a CVD method are 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 400 nm. After forming a Ta film having a thickness of 20 nm by a sputtering method and subsequently forming a copper film having a thickness of 50 nm by a sputtering method, an 8-inch wafer having a copper film having a total thickness of 1000 nm formed by a plating method is formed. used.

<Polishing speed>
The polishing rate was determined by measuring the film thicknesses of the TEOS film (insulating film) and the SiOC film (Low-k film) before and after CMP and converting from the following formula. The obtained results are shown in Table 1.
Polishing rate (Å / min) = (film thickness before polishing−film thickness after polishing) / polishing time

<Scratch evaluation>
The polishing object for scratch evaluation was polished to the SiOC film after polishing the TEOS layer with the wafer (the SiOC film was polished to 20 nm), and then the polished surface was washed with pure water and dried. The dried polished surface was observed with an optical microscope, and scratches were evaluated based on the following evaluation criteria. In addition, (circle) and (triangle | delta) are judged to be a level which does not have a problem practically. The obtained results are shown in Table 1.
-Evaluation criteria-
○: No problem scratch is observed Δ: One or two problem scratches are observed in the wafer surface ×: Many problem scratches are observed in the wafer surface

[Examples 2-44 and Comparative Examples 1-3]
Polishing experiments were conducted under the same polishing conditions as in Example 1 using a polishing liquid prepared by changing the composition (1) in Example 1 to the compositions shown in Tables 1 to 5 below. The results are shown in Tables 1-5.

  The (A) quaternary ammonium cation described in the above table (labeled “quaternary salt” in the table) and the polymer having a sulfone group at the terminal (simply labeled “polymer” in the table) are Refers to an exemplary compound.

The details of the compounds abbreviated in the above examples are shown below.
-Corrosion inhibitor-
BTA: 1,2,3-benzotriazole DBTA: 5,4-dimethyl-1,2,3-benzotriazole DCEBTA: 1- (1,2-dicarboxyethyl) benzotriazole HEABTA: 1- [N, N- Bis (hydroxyethyl) aminomethyl] benzotriazole HMBTA: 1- (hydroxymethyl) benzotriazole

-Organic acid-
The compound names of the compounds B-1 to B-5 having a carboxyl group used as the organic acid are shown in the following table.

-Inorganic particles-
The shape and primary average particle diameter of colloidal silica C-1 to C-5 used as inorganic particles are shown in the following table. In addition, all the colloidal silica described in the following table is manufactured by Fuso Chemical Industries.

According to the above results, when the polishing liquid of this example is used, the polishing rate of TEOS is higher than that of the comparative example, the polishing rate of the SiOC insulating film which is a low-k film is improved, and scratches are also obtained. It turns out that it is excellent also in performance.
On the other hand, it can be seen that the polishing liquid of the comparative example is inferior to the polishing liquid of the example in terms of TEOS polishing rate, SiOC insulating film polishing rate, and scratch performance.

  From the above, it can be seen that the polishing liquid of this example is excellent in the TEOS polishing rate, effectively improves the polishing rate of the SiOC insulating film which is a low-k film, and is also excellent in scratch performance.

Claims (9)

A polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit, and used for polishing a substrate having an insulating film in which a TEOS insulating film and a low-k film are stacked. And
A polishing liquid comprising a quaternary ammonium cation, a corrosion inhibitor, a polymer having a sulfone group or a salt structure thereof, inorganic particles, and an organic acid, and having a pH of 1 to 7. The polymer having a sulfone group or a salt structure thereof at the terminal is represented by the following P-1 to P-21 (n and m are each independently an integer of 2 to 10, x and y are x + y and an integer of 2 to 10, R is The polishing liquid according to claim 1, wherein the polishing liquid is at least one selected from alkyl groups having 1 to 12 carbon atoms.






  The polymer having a sulfone group or a salt structure thereof at the terminal is at least one selected from P-1, P-3 to P-4, and P-6 to P-21. 2. The polishing liquid according to 2. The polishing liquid according to any one of claims 1 to 3, wherein the quaternary ammonium cation is a cation represented by the following general formula (1) or general formula (2).

[In General Formula (1) and General Formula (2), R ^{1 to} R ⁶ each independently represents an alkyl group, alkenyl group, cycloalkyl group, aryl group, or aralkyl group having 1 to 20 carbon atoms; Two of ^{1 to} R ⁶ may be bonded to each other to form a cyclic structure. X represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining two or more thereof. ]   The polishing liquid according to claim 4, wherein the quaternary ammonium cation is a cation represented by the general formula (2).   The polishing liquid according to claim 1, wherein the inorganic particles are at least one kind of inorganic particles selected from silica, alumina, ceria, zirconia, and titania.   7. The polishing liquid according to claim 1, wherein the concentration of the inorganic particles is 0.5 to 15% by mass with respect to the total mass of the polishing liquid. The semiconductor integrated circuit has a barrier layer, and the material constituting the barrier layer is at least one of Ta, TaN, Ti, TiN, Ru, CuMn, MnO ₂ , WN, W, and Co. The polishing liquid according to any one of claims 1 to 7, wherein:   The polishing liquid according to any one of claims 1 to 8 is supplied to a polishing pad on a polishing surface plate and brought into contact with a surface to be polished of a body to be polished so that the surface to be polished and the polishing pad move relative to each other. And a chemical mechanical polishing method characterized by comprising polishing.