JP2009206316A - Polishing liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing liquid which uses solid abrasive grains used for a barrier CMP (Chemical Mechanical Polishing) for polishing a barrier layer made of a barrier metal material, and can independently control polishing speeds of a TEOS layer and an SiOC layer. <P>SOLUTION: The polishing liquid contains (A) di-quaternary ammonium cation, (B) alumina and (C) colloidal silica, and the pH of which is 2.0 to 6.0. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing liquid used in a manufacturing process of a semiconductor device, and more particularly to a polishing liquid suitably used for polishing a barrier layer mainly made of a barrier metal material 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”) is generally performed to remove the barrier metal material (barrier metal) exposed on the surface. 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, polishing scratches, a phenomenon in which the entire polished surface is polished more than necessary (thinning), and the polished metal surface has a dish-like shape. In some cases, a phenomenon in which an insulator between metal wirings is polished more than necessary, and a plurality of metal surfaces of the wiring are recessed in a dish shape (erosion).
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, there has not yet been obtained a technique that can realize a high polishing rate for various films to be polished and can control each polishing rate independently when polishing the barrier layer. There is no current situation.
JP 2003-17446 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 barrier CMP for polishing a barrier layer made of a barrier metal material, which has an excellent polishing rate for the barrier layer, and has various polishing targets. An object of the present invention is to provide a polishing liquid capable of independently controlling the polishing rate for a film.

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.
The polishing liquid of the present invention is a polishing liquid for polishing a barrier layer of a semiconductor integrated circuit, and contains (A) diquaternary ammonium cation, (B) alumina, and (C) colloidal silica, and has a pH of 2. 0.0 to 6.0.

  2. The polishing liquid according to claim 1, wherein the (A) diquaternary ammonium cation is a divalent cation represented by the following general formula (1).

In general formula (1), R ^{1 to} R ⁶ each independently represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and two of R ^{1 to} R ⁶ are bonded to each other to form a ring. May be formed. X represents an alkylene group, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining these.

In the present invention, the mass ratio of (B) alumina to (C) colloidal silica is preferably 1: 9 to 9: 1.
Furthermore, it is a preferable aspect that the sum of the concentrations of (B) alumina and (C) colloidal silica is 0.5 to 15% by mass with respect to the total mass of the polishing liquid.

  In the present invention, (B) the primary average particle diameter of alumina is in the range of 5 to 30 nm, and (C) the primary average particle diameter of colloidal silica is in the range of 10 to 50 nm.

  Furthermore, 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [N, A preferred embodiment is a polishing liquid containing at least one compound selected from the group consisting of N-bis (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole.

  Furthermore, it is a preferred embodiment that contains a compound having a carboxyl group, and that the compound having a carboxyl group is a polishing liquid containing a compound represented by the following general formula (2).

一般式（２）中、Ｒ^７及びＲ^８はそれぞれ独立に炭化水素基を表す。Ｒ^７とＲ^８とは互いに結合して環状構造を形成していてもよい。

In general formula (2), R ⁷ and R ⁸ each independently represent a hydrocarbon group. R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure.

  Furthermore, the polishing liquid of the present invention preferably contains an anionic surfactant or a cationic surfactant.

Although the operation of the present invention is not clear, it is presumed as follows.
It is considered that the polishing characteristics of the two types of abrasive particles can be used by the two different types of abrasive particles contributing to the polishing without interaction. By including a quaternary ammonium cation in the polishing liquid, the electrostatic interaction that causes the agglomeration of the abrasive particles of alumina and colloidal silica can be alleviated, and as a result, the two types of abrasive particles exhibit their respective performances sufficiently. It is thought to be possible. Thus, it is considered that the polishing rate for each film type to be polished could be controlled using the mixing ratio of the abrasive particles.

  According to the present invention, it is possible to provide a polishing liquid capable of obtaining an excellent polishing rate for the barrier layer and independently controlling the polishing rate for various films to be polished.

Hereinafter, specific embodiments of the present invention will be described.
The polishing liquid of the present invention is a polishing liquid for polishing a barrier layer of a semiconductor integrated circuit, and contains (A) diquaternary ammonium cation, (B) alumina, and (C) colloidal silica, and has a pH of 2. It is characterized by being 0.0 to 6.0, and may further contain an optional component as necessary.
Each of the above components 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) Diquaternary ammonium cation]
The polishing liquid of the present invention contains diquaternary ammonium cations (hereinafter sometimes simply referred to as “specific cations”).
The (A) diquaternary ammonium cation in the present invention is not particularly limited as long as it has a structure containing two quaternary nitrogens in the chemical structure. Especially, it is preferable that it is a cation represented by following General formula (1) from a viewpoint of achieving sufficient improvement of a grinding | polishing rate.

In the general formula (1), R ^{1 to} R ⁶ each independently represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group. Two of R ^{1 to} R ⁶ in the general formula (1) may be bonded to each other.
The alkyl group may be an alkyl group having 1 to 20 carbon atoms. Specific examples 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, a butyl group, and a cyclohexyl group are preferable.
The alkenyl group may be an alkenyl group having 2 to 10 carbon atoms, and specific examples thereof include an ethynyl group and a propyl group.

The cycloalkyl group may be an alicyclic alkyl group having 3 to 12 carbon atoms. Specific examples include a cyclohexyl group and a cyclopentyl group, and among them, a cyclohexyl group is preferable.
The aryl group may be an aryl group having 3 to 12 carbon atoms. Specific examples 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 include a benzyl group and a phenethyl group, and among them, a benzyl group is preferable.

  Each of the above groups may further have a substituent, and examples of the substituent that can be introduced include a hydroxyl group, an alkyl group, an amino group, a carboxyl group, a phosphoric acid group, an imino group, a thiol group, a sulfo group, a nitro group. Groups and the like.

X in the general formula (1) 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 alkyl group, an amino group, a carboxyl group, a phosphate group, an imino group, a thiol group, a sulfo group, a nitro group, Groups and the like.

  Hereinafter, although the specific example (exemplary compound A1-A32) of the specific cation in this invention is shown, this invention is not limited to these.

  Among the diquaternary ammonium cations as described above, from the viewpoint of dispersion stability in the slurry, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A12, A14, A15, A18, A19, A23, A24, A29, A30, A31, and A32 are preferable.

The diquaternary ammonium cation in the present invention can be synthesized, for example, by a substitution reaction in which ammonia or various amines act as a nucleophile.
Moreover, a general sale reagent can also be used.

  The counter ion of the specific cation of the present invention may be a monovalent anion or a divalent anion. For example, nitrate ion, sulfate ion, halide ion (for example, bromide ion, chloride ion, fluoride ion and iodine ion) Fluoride ion), citrate ion, phosphate ion, oxalate ion, phthalate ion, maleate ion, gluconate ion, fumarate ion, tartaric acid ion, malate ion, glycolate ion, hydroxide ion, acetate ion , Trifluoroacetate ion, borate ion, lactate ion, thiocyanate ion, cyanate ion, sulfate ion, silicate ion, perhalide ion (eg perbromate ion, perchlorate ion and periodate ion), Chromate ion, p-toluenesulfonate ion, benzenesulfonate ion Methane sulfonate ion, trifluoromethane sulfonate ion, ethane sulfonate ion, diglycolate ion, 2,5-furandicarboxylate ion, 2-tetrahydrofuran carboxylate ion, tetrafluoroborate ion, hexafluorophosphate ion Can be mentioned.

  Among these, nitrate ion, citrate ion, phosphate ion, oxalate ion, phthalate ion, maleate ion, fumarate ion, tartaric acid ion, malate ion, glycol from the viewpoint of suppressing corrosion after polishing Acid ion, hydroxide ion, acetate ion, trifluoroacetate ion, lactate ion, sulfate ion, silicate ion, p-toluenesulfonate ion, benzenesulfonate ion, methanesulfonate ion, trifluoromethanesulfonate ion, ethane Sulfonate ion, diglycolate ion, 2,5-furandicarboxylate ion, 2-tetrahydrofuran carboxylate ion, borate ion, tetrafluoroborate ion and hexafluorophosphate ion are preferred.

  The specific cation addition amount 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 following “polishing liquid used for polishing” is also agreed) Is preferably 0.0001% by mass or more and 1% by mass or less, and more preferably 0.001% by mass or more and 0.3% by mass or less. That is, the amount of the specific cation added is preferably 0.00001% by mass or more from the viewpoint of sufficiently improving the polishing rate, and is preferably 1% by mass or less from the viewpoint of sufficient slurry stability.

[(B) Alumina]
The polishing liquid of the present invention contains (B) alumina as at least a part of the abrasive grains. This alumina refers to a material having Al ₂ O ₃ as a crystal phase, such as fumed alumina or fused alumina, and may be any of α phase, γ phase, δ phase, and κ phase.

  The primary particle diameter of alumina is appropriately selected according to the purpose of use of the abrasive grains, but is preferably in the range of 5 to 100 nm, more preferably 5 to 30 nm, from the viewpoint of preventing polishing flaws. If the primary particle size is too small, the polishing ability is extremely lowered, and if the primary particle size is too large, the abrasive particles may settle.

  The secondary particle size is preferably 5 nm to 1 μm, more preferably 30 nm to 500 nm. As the secondary particle size of the abrasive particles increases, the polishing ability increases, but on the other hand, polishing flaws easily occur and the polishing surface becomes rough. By using particles having a secondary particle size of 1 μm or less, a high polishing rate can be exhibited while the polishing surface remains in good condition.

  The content (concentration) of (B) alumina in the polishing liquid of the present invention is preferably 0.1% by mass to 30% by mass with respect to the total mass including the solvent of the polishing liquid when used for polishing. More preferably, it is 0.5 mass% or more and 15 mass% or less. That is, the content of (B) alumina is preferably 0.5% by mass or more in terms of polishing the barrier layer at a sufficient polishing rate, and particularly preferably 15% by mass or less in terms of storage stability.

[(C) colloidal silica]
The polishing liquid of the present invention contains colloidal silica as at least a part of the abrasive grains.
(C) The colloidal silica is preferably colloidal silica obtained by hydrolysis of alkoxysilane, which does not contain impurities such as alkali metals inside the particles. 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.

  (C) The primary particle size of colloidal silica is appropriately selected according to the purpose of use of the abrasive grains, but is generally about 10 to 200 nm, but in the range of 10 to 100 nm from the viewpoint of not generating polishing flaws. It is preferable that the thickness is in the range of 10 to 50 nm.

  In the present invention in which (B) alumina and (C) colloidal silica are used in combination, the primary particle diameter of alumina is in the range of 5 to 30 nm, and the primary particle diameter of colloidal silica is in the range of 10 to 50 nm. Good product selectivity and high polishing rate.

  The content (concentration) of (C) colloidal silica in the polishing liquid of the present invention is preferably 0.1% by mass to 30% by mass with respect to the total mass including the solvent of the polishing liquid when used for polishing. More preferably, it is 0.5 mass% or more and 15 mass% or less. That is, the content of (C) colloidal silica is preferably 0.5% by mass or more in terms of polishing the barrier layer at a sufficient polishing rate, and particularly preferably 15% by mass or less in terms of storage stability.

The polishing liquid of the present invention contains two types of abrasive particles of (B) alumina and (C) colloidal silica. The content ratio of the abrasive particles is preferably 1: 9 to 9: 1 in terms of mass ratio. More preferably, it is 3: 7-7: 3.
The polishing rate of the TEOS film and the SiOC film can be adjusted by the content ratio of the abrasive particles.

(Corrosion inhibitor)
It is preferable to add a corrosion inhibitor to the polishing liquid of the present invention. It is considered that the corrosion inhibitor adsorbs on 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, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzo Triazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole, 1- (hydroxymethyl) benzotriazole, 1,2,3,4-tetrazole, 5-amino-1,2,3,4 -Tetrazole, 5-methyl-1,2,3,4-tetrazole, 1H-tetrazole-5-acetic acid, 1H-tetrazole-5-succinic acid, 1,2,3,4-tetrazole, 5-amino-1, 2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1H-tetrazole-5-acetic acid, 1H-tetrazole-5-succinic acid, 2,3-triazole, 4-amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 4-carboxy-1H-1,2,3-triazole, 4,5- Dicarboxy-1H-1,2,3-triazole, 1H-1,2,3-triazole-4-acetic acid, 4-carboxy-5-carboxymethyl-1H-1,2,3-triazole, 1,2, 4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-carboxy-1,2,4-triazole, 3,5-dicarboxy-1 2,4-triazole, 1,2,4-triazole-3-acetic acid, 1H benzotriazole, 1H-benzotriazole-5-carboxylic acid, and the like.

  Among these, 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [N, N-bis More preferably, it is selected from (hydroxyethyl) aminomethyl] benzotriazole and 1- (hydroxymethyl) benzotriazole.

  The addition amount of such a corrosion inhibitor is preferably 0.01% by mass or more and 0.2% by mass or less, and 0.05% by mass or more and 0.2% by mass with respect to the mass of the polishing liquid used for polishing. % Or less is more preferable. 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.

[Compound having a carboxyl group]
The polishing liquid of the present invention preferably contains a compound having a carboxyl group (hereinafter appropriately referred to as “organic acid”). 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 from the viewpoint of the polishing rate structure, a compound represented by the following general formula (2) should be selected. 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 (2) represents R ⁷ and R ⁸ each independently a hydrocarbon group, preferably represents a hydrocarbon group having 1 to 10 carbon atoms.
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, a C1-C10 alkylene group (for example, a methylene group, a cycloalkylene group, etc.), an arylene group (for example, a phenylene group), an alkyleneoxy group, etc. are 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 (2) include 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid, methoxy Phenylacetic acid, phenoxyacetic acid and the like can be mentioned. Among them, 2,5-furandicarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid and phenoxyacetic 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 amount of the carboxyl group-containing compound (preferably, the compound represented by the general formula (2)) is 0.1 mass relative to the mass of the polishing liquid used for polishing. % To 5% by mass is preferable, and 0.5% to 2% by mass is more preferable. That is, the content of such a compound having a carboxyl group (organic acid) is preferably 0.1% by mass or more in terms of achieving a sufficient polishing rate, and 5% by mass from the point of not causing excessive dishing. The following is preferred.

(Compound represented by the general formula (3))
Furthermore, the polishing liquid of the present invention preferably contains at least one of a compound represented by the following general formula (3) or a polymer containing a structural unit represented by the following general formula (3).

In the general formula (3), R ⁹ is an ethylene oxide unit or a propylene oxide unit, and R ^{10 to} R ¹⁵ are each independently a hydrogen atom, a hydroxyl group, an alkyl group, a sulfo group, a carboxyl group, and a hydrocarbon containing them. Represents any of the groups.

  By incorporating such a compound represented by the general formula (3) or a polymer compound containing the structural unit represented by the general formula (3) in the polishing liquid, the interaction between the SiOC film and the abrasive grains is increased. It is possible to improve the polishability of a Low-k film such as a SiOC film.

R ⁹ in the general formula (3) is an ethylene oxide unit or a propylene oxide unit. That is, these ethylene oxide units may be one unit or a plurality of units (n is 2 or more in (CH ₂ CH ₂ O) _n ). In the case of a plurality of units, n is preferably in the range of 2 or more and 10 or less.

The “polymer containing the structural unit represented by the general formula (3)” is not particularly limited as long as the phenyl group in the general formula (3) is configured to be a part of the main chain. For example, as shown in the following general formula (4), a polymer polymerized via R ¹⁰ and R ¹⁴ is desirable. In this case, m is preferably 2 or more and 10 or less, and more preferably 2 or more and 5 or less.

一般式（４）のＲ^９、Ｒ^１１〜Ｒ^１３、Ｒ^１５は一般式（３）のそれと同義である。

R < ⁹ >, R < ¹¹ > -R < ¹³ >, R < ¹⁵ > of General formula (4) is synonymous with that of General formula (3).

Hereinafter, specific examples [Exemplary compounds (P-1) to (P-28)] of the polymer containing the compound represented by the general formula (3) and the structural unit represented by the general formula (4) in the present invention are shown. However, the present invention is not limited to these.
In the following exemplified compounds, n and m are 1 to 5, and x and y in the exemplified compound P-15 are x + y = 10, and x is 1 to 5. The notation of —SO ₃ H · Na and —SO ₃ H · K means both a compound of —SO ₃ H or —SO ₃ Na and a compound of both —SO ₃ H or —SO ₃ K, respectively.

  In the polishing liquid of the present invention, the addition amount of the compound represented by the general formula (3) and the polymer containing the structural unit represented by the general formula (3) is based on the mass of the polishing liquid used for polishing. 0.0001% by mass or more and 10% by mass or less is preferable, and 0.001% by mass or more and 1% by mass or less is more preferable. That is, the SiOC polishing rate can be improved by setting the addition amount of the compound in the above range.

Furthermore, it is preferable to add an oxidizing agent, a pH adjuster, a chelating agent and the like to the polishing liquid of the present invention. This will be described below.
(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 iron (III) in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III) and iron bromide (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 state in 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-0.6 mol.

(PH adjuster)
The polishing liquid of the present invention needs to have a pH of 2.0 to 6.0 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 buffering agent can be 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 ammonia, organic ammonium hydroxides such as 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.

  The addition amount of the alkali / acid or the buffer 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 the polishing liquid when used for polishing. , 0.003 mol to 0.5 mol is more preferable.

(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-dihydroxy-4,6-disulfonic acid.

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]
As a material constituting the barrier layer to be polished by the polishing liquid of the present invention, generally a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, WN are particularly preferable, and Ta, TaN are particularly preferable. preferable.

[Interlayer insulation film]
As an interlayer insulating film 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 material having a relative dielectric constant of about 3.5 to 2.0 (for example, Examples thereof include organic polymer-based, SiOC-based, SiOF-based, etc., and an interlayer insulating film including abbreviated as a Low-k film).
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.

[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, brought into contact with the surface to be polished of the object to be polished, and the surface to be polished and the polishing pad are moved 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 having the surface to be polished (film to be polished) against the polishing pad is preferably 0.68 to 34.5 KPa, the in-plane uniformity of the object to be polished at the polishing rate and the flatness of the pattern 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 be one containing abrasive grains generally used for polishing (for example, ceria, silica, alumina, resin, 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 was prepared with the composition shown below.
<Composition (1)>
Diquaternary ammonium cation: hexamethonium chloride 0.2 g / L
Corrosion inhibitor: benzotriazole (BTA) 1.0 g / L
・ Colloidal silica 25g / L
・ Alumina 25g / L
-Compound having a carboxyl group: Diglycolic acid 1 g / L
・ Pure water is added and the total volume is 1000mL
pH (adjusted with ammonia water and nitric acid) 3.5
Hydrogen peroxide 10ml

The following polishing evaluation was performed using the prepared polishing liquid.
(Evaluation methods)
Using a device “MA-300D” manufactured by Musashino Electronics Co., Ltd. as a polishing apparatus, the wafer shown below was polished under the following conditions while supplying slurry.
Table rotation speed: 112 rpm
Head rotation speed: 113 rpm
Polishing pressure: 9.19 kPa
Polishing pad: Rodel Nitta Co., Ltd. IC1400 XY-K-Pad
Polishing liquid supply speed: 50 ml / min

<Polishing rate evaluation>
As a wafer for polishing rate evaluation, a wafer obtained by cutting an 8-inch wafer in which a TEOS film (tetraethoxysilane film) and a SiOC film (BLACKDIAMMOND Applied Materials, Inc) to be polished on a Si substrate are cut into 6 cm × 6 cm is used. used.

<Polishing speed>
The polishing rate was determined by measuring the film thicknesses of the TEOS film and SiOC film before and after CMP and converting from the following formula.
Polishing rate (nm / min.) = (Various film thicknesses before polishing−various film thicknesses after polishing) / polishing time Table 1 shows the results obtained.

<Dispersion evaluation of polishing liquid>
The dispersibility of the abrasive particles contained in the polishing liquid was evaluated based on the following evaluation criteria. After preparing the polishing liquid, it was allowed to stand at room temperature for 1 hour, and it was judged by visual observation whether the abrasive particles had settled or gelled. In addition, it is judged that ○ is a level with no practical problem.
-Evaluation criteria-
○: Settling of abrasive particles or gelation cannot be visually confirmed.
X: It can visually confirm that the abrasive particles are settled or gelled.

[Examples 2-32 and Comparative Examples 1-5]
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 3 below. The results are shown in Tables 1 to 3.

Specific cations A1 to A32 described in Tables 1 to 3 above refer to the exemplified compounds described above.
Furthermore, Table 4 shows the average primary particle diameter and average secondary particle diameter of alumina B1 and B2 and colloidal silica C1 to C5 described in Tables 1 to 3 above. The average particle size was determined by the photon correlation method. Table 4 also shows the average primary particle sizes of ceria and titania used in the comparative examples.

Moreover, the corrosion inhibitor used in the said Table 1-Table 3 is as follows.
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

  Furthermore, Table 5 shows compounds having a carboxyl group used in Tables 1 to 3 (indicated as “organic acids” in Tables 1 to 3).

According to Tables 1 to 3, when the polishing liquids of Examples 1 to 32 were used, no settling or gelation of the abrasive particles observed in Comparative Examples 1 to 3 was observed. From this, it can be seen that in a polishing liquid containing two kinds of abrasive particles, a combination of silica and alumina is suitable, and it is necessary to contain a diquaternary ammonium cation.
In the polishing liquids of Examples 1 to 32, it can be seen that the ratio of the TEOS film polishing rate to the SiOC film polishing rate can be adjusted by the composition ratio and concentration of the two types of polishing particles. Both the TEOS film and the SiOC film It can be seen that the polishing rate of the film is high at the same time. Further, it can be seen that Comparative Examples 4 and 5 can polish one of the films, but are not suitable for polishing both the TEOS film and the SiOC film.

Claims (7)

  A polishing liquid for polishing a barrier layer of a semiconductor integrated circuit, comprising (A) a diquaternary ammonium cation, (B) alumina, and (C) colloidal silica, and having a pH of 2.0 to 6.0 A polishing liquid characterized by being. The polishing liquid according to claim 1, wherein the (A) diquaternary ammonium cation is a divalent cation represented by the following general formula (1).

[In General Formula (1), R ^{1 to} R ⁶ each independently represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and two of R ^{1 to} R ⁶ are bonded to each other. To form a ring. X represents an alkylene group, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining these. ]   The polishing liquid according to claim 1 or 2, wherein a mass ratio of (B) alumina to (C) colloidal silica is 1: 9 to 9: 1.   4. The sum of the concentrations of (B) alumina and (C) colloidal silica is 0.5 to 15% by mass with respect to the total mass of the polishing liquid. The polishing liquid according to item 1.   The primary average particle diameter of (B) alumina is in the range of 5 to 30 nm, and the primary average particle diameter of (C) colloidal silica is in the range of 10 to 50 nm. The polishing liquid according to any one of the above.   Furthermore, 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl) benzotriazole, 1- [N, N-bis (hydroxyethyl) aminomethyl] benzotriazole and at least one compound selected from the group consisting of 1- (hydroxymethyl) benzotriazole is included. The polishing liquid according to item 1. Furthermore, it contains the compound which has a carboxyl group, and the compound which has this carboxyl group is a compound represented by following General formula (2), Any one of Claims 1-6 characterized by the above-mentioned. The polishing liquid as described.

[In General Formula (2), R ⁷ and R ⁸ each independently represent a hydrocarbon group. R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure. ]