TWI480367B - Polishing liquid - Google Patents

Description

Slurry

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

In the development of a semiconductor device typified by a semiconductor integrated circuit (hereinafter referred to as "LSI"), for miniaturization. In recent years, high speed has been demanded by the miniaturization and thickening of wiring. Highly integrated. Various techniques such as chemical mechanical polishing (hereinafter referred to as "CMP") have been used for the technology required for this. This CMP is an indispensable technique for applying a flat surface of a film to be processed such as an interlayer insulation film, forming a plug, or forming a buried metal wiring, and is used for performing planarization or removal of the substrate. An excess metal film at the time of wiring formation or an excess barrier layer on the insulating film.

The general method of CMP is to attach a polishing pad on a circular platen, impregnate the surface of the polishing pad with a polishing liquid, and press the surface of the substrate (wafer) against the pad and apply a predetermined pressure from the back surface thereof ( In the state of the polishing pressure, both the polishing table and the substrate are rotated, and the surface of the substrate is flattened by the mechanical friction generated.

In the case of manufacturing a semiconductor device such as an LSI, a method of forming a fine wiring into a plurality of layers is generally employed. However, when a metal wiring such as Cu is formed in each layer, the wiring material is prevented from diffusing into the interlayer insulating film or wiring is improved. For the purpose of adhesion of materials, measures for forming barrier metals such as Ta or TaN, Ti, TiN, etc., are employed.

In order to form each wiring layer, CMP (hereinafter referred to as "metal film CMP" (hereinafter referred to as "metal film CMP" (hereinafter referred to as "metal film CMP") is generally employed in a one-stage or multi-stage manner for removing excess wiring material plated by plating or the like. Metal film CMP)") Next, the CMP of the barrier metal material (barrier metal) exposed to the surface (hereinafter referred to as "barrier metal CMP") is removed. However, the wiring portion is excessively polished due to the metal film CMP, that is, so-called "dishing" or even "erosion" is a problem.

In order to alleviate the shallow dishing, after the metal film CMP, the barrier metal CMP is secondarily required to adjust the polishing speed of the metal wiring portion and the polishing speed of the barrier metal portion, so as to form a final shallow dish. A wiring layer having a small concavity such as etching or etching. In other words, when the barrier metal or the interlayer insulating film is relatively slower than the metal wiring material in the barrier metal CMP, the wiring portion is already shallowed by polishing or the like, or the result thereof is caused. The etching is so that the polishing speed of the barrier metal or the insulating film layer is preferably appropriately large. It has the advantage of increasing the yield of the barrier metal CMP, and in fact, it is mostly caused by the metal film CMP, and it is required to relatively increase the barrier metal or the insulating film for the reasons described above. It is also preferable from the viewpoint of the polishing rate of the layer.

A grinding solution for metal for CMP, generally containing a polishing particle (for example, alumina, ceria) and an oxidizing agent (oxidizing agent) (eg, hydrogen peroxide, persulfuric acid). The basic mechanism is believed to achieve grinding by oxidizing the metal surface with an oxidizing agent and then removing the oxide film with abrasive particles.

However, when CMP is performed using a polishing liquid containing such solid abrasive grains, there is a possibility that a grinding flaw (scratch) or a polishing surface is required to be polished (thinning). One part of the polished metal surface is excessively ground so that the surface is dished into a dish (shallow disc), and the insulator of the metal wiring is subjected to grinding more than necessary, and only the central portion of the plurality of wiring metal faces is subjected to comparison. Deep grinding and the surface is dished into a dish (etching).

Further, since the polishing liquid containing the solid abrasive grains is used, the washing step which is usually performed to remove the polishing liquid remaining on the semiconductor surface after the grinding tends to be complicated, and the liquid (the waste liquid) is treated for the treatment thereof. However, there is a need for settlement in the separation of solid abrasive grains and the like in terms of cost.

Regarding the polishing liquid containing such solid abrasive grains, various studies as described below have been made.

For example, there has been proposed a CMP abrasive and a polishing method for the purpose of performing high-speed polishing with almost no abrasive damage (see, for example, Japanese Patent Laid-Open No. 2003-17446), an improvement in CMP cleaning. A polishing composition and a polishing method (see, for example, Japanese Laid-Open Patent Publication No. 2003-142435), and a polishing composition for preventing agglomeration of abrasive grains (see, for example, Japanese Patent Laid-Open No. 2000-84832 Bulletin).

However, even if there is a slurry as described above, it is still A technique capable of realizing a high polishing rate at the time of polishing a necessary layer and suppressing scratches due to agglomeration of solid abrasive grains is not obtained.

In particular, in recent years, with the further miniaturization of wiring, the low dielectric constant of a conventional interlayer insulating film such as TEOS (tetraethoxysilane) has been evolved to have a relative dielectric constant lower than that of TEOS (tetraethoxysilane). The material is used as an insulating film. These insulating films are referred to as "Low-k films", and are formed of materials such as organic polymer, SiOC, or SiOF. These are generally used for lamination with an insulating film, but since the strength is lower than that of the prior insulating film, the problem of excessive grinding or scratching as described above is more remarkable in the processing of CMP.

SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing liquid which is a polishing liquid for solid abrasive grains for chemical mechanical polishing in a planarization step of a semiconductor integrated circuit, which can have a TEOS insulating film which is laminated and low in general. The substrate of the insulating film of the dielectric constant Low-k film obtains a superior polishing rate for the TEOS insulating film, and can effectively suppress the use of a low-strength insulating film such as a Low-k film. The polishing rate of the Low-k film can also achieve scratching due to agglomeration of the solid abrasive grains.

As a result of intensive research, the inventors of the present invention have found that the above problems can be solved by using the polishing liquid described below, and finally achieve the object.

The polishing liquid of the present invention is characterized in that it is tied to a semiconductor integrated circuit The chemical casting process for the chemical mechanical polishing, comprising (A) a quaternary ammonium cation, (B) a corrosion inhibitor, (C) a nonionic surfactant, and (D) colloidal silica, And the pH is from 2.5 to 5.0.

In the present invention, it is preferred that the (A) quaternary ammonium cation is a cation represented by the general formula (1) or the general formula (2) as follows: [In the general formula (1), the general formula (2), R ¹ to R ⁶ each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group, or a carbon number of 1 to 20; The aralkyl group, two of R ¹ to R ⁶ may also be bonded to each other to form a cyclic structure. X is a group which represents an alkylene group having 1 to 10 carbon atoms, an alkenyl group, an alkynylene group, a cycloalkyl group, an aryl group, or a combination of two or more. ].

The "(C) nonionic surfactant" of the present invention may be selected from the group consisting of an ether type nonionic surfactant, an ether ester type nonionic surfactant, and an ester type nonionic surfactant. One or more of the group; wherein, a compound represented by the formula (3) or the formula (4) as described below is suitably used:

R-O-(CH ₂ CH ₂ O) _n -H of the formula (3) [In the formula (3), R represents an alkyl group having 2 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, and an aromatic group. The base or aralkyl group, n represents the number of bonds of the polyoxyethylene group, and is an integer of 2 to 30. 〕

[In the formula (4), R ¹ to R ⁴ each independently represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms, a, b, c , d, e, and f represent the number of bonds of the polyoxyethylene group, respectively, and a+b+c+d+e+f is 20 to 70. ].

In the polishing liquid of the present invention, the concentration of the (D) colloidal ceria is from 0.5 to 15% by mass based on the total weight of the polishing liquid, and the primary average particle diameter of the (D) colloidal ceria used is A range of 20 to 50 nm is a preferred mode.

Further, "(B) corrosion inhibitor" is preferably selected from 1,2,3-benzobenzene Triazole, 5,6-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-( At least one of a group consisting of 2,3-dihydroxypropyl)benzotriazole, 1-(2,3-dihydroxypropyl)tolyltriazole, and 1-(hydroxymethyl)benzotriazole a compound.

In the polishing liquid of the present invention, it is preferred that each component as described above further contains (E) a compound having a carboxyl group represented by the following formula (5): Formula (5) R ⁷ -O-R ⁸ -COOH [In the formula (5), R ⁷ and R ⁸ each independently represent a hydrocarbon group. The R ⁷ and R ⁸ groups may be bonded to each other to form a cyclic structure. ].

According to the present invention, it is possible to provide a polishing liquid using solid abrasive grains for chemical mechanical polishing in a planarization step of a semiconductor integrated circuit, which can have a laminated TEOS insulating film and a low dielectric constant. The substrate of the insulating film of the Low-k film obtains a superior polishing rate for the TEOS insulating film, and can effectively suppress the Low-k even in the case of using a low-strength insulating film such as a Low-k film. The polishing rate of the film can also be achieved by suppressing scratching due to agglomeration of the solid abrasive grains.

[Best Embodiment of the Invention]

Hereinafter, specific modes of the present invention will be described.

The polishing liquid of the present invention is used for chemical mechanical polishing in a semiconductor integrated circuit planarization step, comprising (A) a quaternary ammonium cation, (B) a corrosion inhibitor, (C) a nonionic surfactant, and D) Colloidal cerium oxide and having a pH of from 2.5 to 5.0. The polishing liquid of the present invention may further contain any component as needed.

The components contained in the polishing liquid of the present invention may be used alone or in combination of two or more.

The term "polishing liquid" as used in the present invention means not only a polishing liquid used in polishing (that is, a polishing liquid which is diluted as needed) but also a concentrated liquid of a polishing liquid. The term "concentrate or concentrated slurry" means a slurry prepared to have a higher solute concentration than the slurry used directly for polishing, and when used for grinding, water or an aqueous solution is required. Dilute it for use in the grinder. The dilution ratio is usually 1 to 20 times by volume. In the present specification, the terms "concentrate" and "concentrate" are used according to the conventional expression to mean "denser" and "denser liquid". Semantic different terms of liquids that have undergone physical concentration operations such as evaporation have been used differently.

Hereinafter, the components used to constitute the polishing liquid of the present invention will be described in detail.

[(A) quaternary ammonium cation]

The slurry of the present invention contains a quaternary ammonium cation (hereinafter, At the time, it is simply called "specific cation". ).

The quaternary ammonium cation of the present invention is not particularly limited as long as it has a structure in which one or two quaternary nitrogens are contained in the molecular structure. In particular, from the viewpoint of achieving a sufficient polishing rate, a cation represented by the following formula (1) or formula (2) is preferred.

In the above formula (1) and formula (2), R ¹ to R ⁶ each independently represent an alkyl group, an alkenyl group, an alkynyl group or a cycloalkyl group having 1 to 20 carbon atoms. 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.

The alkyl group having 1 to 20 carbon atoms as R ¹ to R ⁶ , specifically, includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl and the like. Among them, preferred are methyl, ethyl, propyl and butyl.

Further, as the alkenyl group of R ¹ to R ⁶ as described above, the number of carbon atoms is preferably from 2 to 10, and specifically, it includes a vinyl group, a propenyl group or the like.

As the alkynyl group of R ¹ to R ⁶ as described above, specifically, it includes a butynyl group, a pentynyl group, a hexynyl group and the like.

As the cycloalkyl group of R ¹ to R ⁶ as described above, specifically, it includes a cyclohexyl group, a cyclopentyl group and the like, and among them, a cyclohexyl group is preferred.

As the aryl group of R ¹ to R ⁶ as described above, specifically, it includes a phenyl group, a naphthyl group and the like, and among them, a phenyl group is preferred.

As the aralkyl group of R ¹ to R ⁶ as described above, specifically, it includes a benzyl group or the like, and among them, a benzyl group is preferred.

Each of the groups represented by R ¹ to R ⁶ as described above may further have a substituent, and the substituent which may be introduced includes a hydroxyl group, an amine group, a carboxyl group, a heterocyclic group, a pyridinium group, an amino alkane. A group, a phosphate group, an imido group, a thiol group, a sulfo group, a nitro group or the like.

X in the above formula (2) is an alkylene group having 1 to 10 carbon atoms, an alkenyl group, an alkynylene group, a cycloalkyl group, an aryl group, or a combination of two or more. The basis of the law.

Further, the bonding group represented by X may contain -S-, -S(=O) ₂ -, -O-, one-C (=) in addition to the organic bonding group as described above. O) One.

The alkyl group having 1 to 10 carbon atoms as described above, specifically, includes methylene, ethyl, propyl, butyl, pentyl, hexyl, and hexylene. The base, the octyl group and the like are preferred, and among them, an ethyl group and a pentyl group are preferred.

The alkenyl group as described above, specifically, includes a vinyl group, a propylene group and the like, and among them, a propenyl group is preferred.

As described above, an alkynyl group, in particular, includes: an ethynyl group And a propynyl group or the like, wherein a propynylene group is preferred.

The cycloalkyl group as described above, specifically, includes a cyclohexylene group, a cyclopentylene group and the like, and among them, a cyclohexyl group is preferred.

The aryl group as described above, specifically, includes a phenyl group and a naphthyl group, and among them, a phenyl group is preferred.

Each of the bonding groups as described above may further have a substituent, and the substituents which may be introduced include: a hydroxyl group, an amine group, a sulfonyl group, a carboxyl group, a heterocyclic group, a pyridinium group, an aminoalkyl group, a phosphoric acid group. Base, imine group, thiol group, sulfo group, nitro group and the like.

Hereinafter, specific examples of the (A) quaternary ammonium cation (specific cation) of the present invention [exemplified compounds (A-1) to (A-46)] will be exemplified, but the present invention is not limited to the examples. By.

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

The (A) quaternary ammonium cation (specific cation) of the present invention can be synthesized by, for example, a substitution reaction using ammonia or various amines as a nucleating agent.

In addition, commercially available reagents are also commercially available.

In the (A) quaternary ammonium cation (specific cation) of the present invention, the amount of the quaternary ammonium cation (specific cation) added is relative to the polishing liquid used for polishing (that is, when diluted with water or an aqueous solution, the diluted polishing liquid is used. The "grinding liquid used for polishing" is also synonymous.), it is preferably 0.0001% by mass or more and 1% by mass or less, more preferably 0.001% by mass or more and 0.3% by mass or less. In other words, the amount of the specific cation added is preferably 0.0001% by mass or more from the viewpoint of sufficiently increasing the polishing rate, and is preferably from the viewpoint of stability of a sufficient slurry. It is 03% by mass or less.

[(B) Corrosion Inhibitor]

The polishing liquid of the present invention contains a corrosion inhibitor for adsorbing a film formed on the surface to be polished to control corrosion of the metal surface. The corrosion inhibitor of the present invention preferably has three or more nitrogen atoms in the molecule and contains a heteroaromatic ring compound having a condensed ring structure. The "three or more nitrogen atoms" are preferably used to form atoms of the condensed ring, and the heteroaromatic ring compounds are preferably benzotriazole, and various substituents are introduced into the benzotriazole. a derivative.

The "corrosion inhibitor" which can be used in the present invention includes: benzotriazole, 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1 -(1,2-dicarboxyethyl)benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole, 1-(hydroxymethyl)benzotriazole Etc. "(B) Corrosion inhibitor" as described above includes: selected from 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, Tolyltriazole, 1-(1,2-dicarboxyethyl)tolyltriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]tolyltriazole, 1-(2, a compound in a group consisting of 3-dihydroxypropyl)benzotriazole, 1-(2,3-dihydroxypropyl)tolyltriazole, and 1-(hydroxymethyl)benzotriazole; More preferably, it is selected from the group consisting of 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, tolyltriazole, 1-(1,2-di Carboxyethyl)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)benzotriazole.

The amount of the (B) corrosion inhibitor added is preferably 0.01% by mass or more and 0.2% by mass or less, more preferably 0.05% by mass or more and 0.2% by mass or less based on the mass of the polishing liquid used for polishing. In other words, the amount of the addition of the corrosion inhibitor is preferably 0.01% by mass or more from the viewpoint of not expanding the shallow dish, and is preferably 0.2% by mass or less from the viewpoint of storage stability. .

[(C) Nonionic surfactant]

The polishing liquid of the present invention contains at least one nonionic surfactant .

In the polishing liquid of the present invention, by adjusting the type and amount of the nonionic surfactant to be used, the polishing rate can be increased or the polishing rate of the insulating layer can be controlled.

The type of "nonionic surfactant" is not particularly limited and may be selected from ether type nonionic surfactants, ether ester type nonionic surfactants, and ester type nonionic surfactants depending on the purpose. Among the ethnic groups that are formed.

The "ether type" includes polyoxyalkylene alkyl ether, polyoxyalkylene alkylphenyl ether, polyoxyethylene-polyoxypropylene block copolymer, and the like. The "ether ester type" includes glycerin of polyoxyethylene ether, sorbitan ester of polyoxyethylene ether, and sorbitol ester of polyoxyethylene ether. The "ester type" includes sorbitan ester, glycerin ester, propylene glycol ester, polyethylene glycol fatty acid ester, and the like.

Among these, from the viewpoint of efficacy, an ether type surfactant such as a polyoxyalkylene alkyl ether or an ester type such as sorbitan ester or polyethylene glycol fatty acid ester is preferred. Ionic surfactant.

Here, the "ether type nonionic surfactant" includes a compound represented by the following formula (3).

General formula (3) R-O-(CH ₂ CH ₂ O) _n -H

In the formula (3), R represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms.

The n series represents the number of bonds of the polyoxyethylene structure and represents an integer of 2 to 30, preferably in the range of 2 to 20.

In the general formula (3), the balance of hydrophilicity and hydrophobicity depends on the number of carbon atoms or the structure of the alkyl group or the like in R, and the number of bonds with the polyoxyethylene chain, and R and n are preferred. The combination includes the following.

That is, R is preferably an alkyl group having 8, 10, 12, 16 carbon atoms, and n is a compound of 2 to 20.

Specific examples of the nonionic surfactant represented by the general formula (3) include, for example, polyoxyethylene lauryl ether, polyethylene oxide cetyl ether, polyoxyethylene lauryl ether, polyoxidation Vinyl oleyl ether, polyoxyethylene myristyl ether, polyoxyethylene octyl lauryl ether, polyethylene oxide behenyl ether, and the like.

The nonionic surfactant represented by the general formula (3) can be obtained from a commercially available commercial grade product such as the EMULGEN series available from EMULGEN 210P, 404, etc. manufactured by Kao Corp.

Further, other preferred examples of the "ester type nonionic surfactant" include compounds represented by the following formula (4).

In the formula (4), R ¹ to R ⁴ each independently represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms; a, b, c, d, e, and f represent the number of bonds of the polyoxyethylene group, respectively, and a+b+c+d+e+f is 20 to 70.

R ¹ to R ⁴ in the formula (4) are synonymous with R in the formula (3), and the preferred mode is also the same.

the following. Specific examples of the nonionic surfactant represented by the general formula (4) are exemplified, but the present invention is not limited thereto.

The nonionic surfactant represented by the formula (4) can be obtained from a commercially available commercial grade product such as RHEODOL 430V, 440V, 460V manufactured by Kao Corporation.

In the polishing liquid of the present invention, these (C) nonionic surfactants may be used singly or in combination of two or more kinds thereof.

(C) The amount of the nonionic surfactant added is preferably from 0.001 to 10 g, more preferably from 0.01 to 5 g, particularly preferably from 0.01 to 1 liter of the polishing liquid used in the polishing. 1 g. In other words, the amount of the surfactant added is preferably 0.01 g or more in order to obtain sufficient efficacy, and is preferably 1 g or less from the viewpoint of preventing a decrease in the CMP rate.

[(D) colloidal cerium oxide]

The slurry of the present invention contains at least a portion of the abrasive particles containing colloidal cerium oxide.

The colloidal cerium oxide is preferably a colloidal cerium oxide obtained by hydrolysis of an alkoxy decane in the absence of an alkali metal or the like inside the particles. On the other hand, although colloidal cerium oxide produced by a method of removing alkali by an aqueous citric acid solution can also be used, in this case, alkali metal remaining inside the particles is slowly eluted. The impact of impact and grinding performance. From such viewpoints, it is more preferred to use a solvent obtained by hydrolysis of alkoxydecane as a starting material.

The particle size of the colloidal cerium oxide can be appropriately selected depending on the purpose of use of the abrasive granules, and is usually about 10 to 200 nm. From the viewpoint of not causing abrasion damage, it is preferred that the primary average particle diameter is In the range of 20 to 50 nm.

The content (concentration) of the (D) colloidal cerium oxide in the polishing liquid of the present invention is preferably 0.5% by mass or more and 15% by mass or less, more preferably 3%, based on the mass of the polishing liquid used for polishing. The mass% or more and 12 mass% or less are particularly preferably 5% by mass or more and 12% by mass or less. That is, (D) the content of colloidal cerium oxide, from polishing the barrier layer at a sufficient polishing rate In view of the viewpoint, it is preferably 0.5% by mass or more, and is preferably 15% by mass or less from the viewpoint of storage stability.

In the polishing liquid of the present invention, (D) abrasive particles other than colloidal cerium oxide may be used in combination as long as the effect of the present invention is not impaired, but in this case, (D) colloidal state in all the abrasive grains The content of cerium oxide is preferably 50% by mass or more, and particularly preferably 80% by mass or more. All of the abrasive grains contained may also be (D) colloidal cerium oxide.

For the polishing liquid of the present invention, the abrasive granules which can be used together with (D) colloidal cerium oxide include: fumed silica, cerium oxide, aluminum oxide, titanium oxide, etc. . The size of the abrasive grains used in combination is preferably the same as or higher than (D) colloidal cerium oxide, and more preferably 2 times or less.

In the polishing liquid of the present invention, components other than the essential components (A) to (D) as described above may be appropriately added as needed. The description of these additional ingredients is as follows.

[(E) a compound having a carboxyl group]

The polishing liquid of the present invention preferably contains (E) a compound having a carboxyl group (hereinafter referred to as "organic acid" as appropriate). 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, it is preferred to select a formula (5) as described below. ) the compound represented.

Further, the number of carboxyl groups present in the molecule is preferably from 1 to 4, and more preferably from 1 to 2 from the viewpoint of being inexpensive to use.

General formula (5) R ⁷ -O-R ⁸ -COOH

In the above formula (5), R ⁷ and R ⁸ each independently represent a hydrocarbon group, and preferably represent a hydrocarbon group having 1 to 10 carbon atoms.

R ⁷ is a monovalent hydrocarbon group, preferably, for example, an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, a cycloalkyl group, etc.), an aryl group (e.g., a phenyl group, etc.), an alkoxy group, an aryloxy group, or the like. .

R ⁸ is a divalent hydrocarbon group, preferably, for example, an alkylene group having 1 to 10 carbon atoms (e.g., a methylene group, a cycloalkyl group, etc.), an aryl group (e.g., a phenyl group, etc.), an alkoxy group. Base.

The hydrocarbon group represented by R ⁷ and R ⁸ may further have a substituent, and the substituent which may be used for introduction includes, for example, an alkyl group having 1 to 3 carbon atoms, an aryl group, an alkoxy group, a carboxyl group, etc., if substituted Where the group is a carboxy group, then the compound will have a complex number of substituents.

Further, R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure.

The compound represented by the above formula (5) includes, for example, 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid (3- A diglycolic acid, a methoxyacetic acid, a methoxyphenylacetic acid, a phenoxyacetic acid or the like; wherein, from the viewpoint of polishing the surface to be polished at a high speed, it is preferably 2,5- Furan dicarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid.

In the polishing liquid of the present invention, (E) a compound having a carboxyl group (preferably a compound represented by the formula (5)) is added in an amount relative to the use thereof. The weight of the polishing liquid at the time of polishing is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 2% by mass or less. In other words, the content of the compound having a carboxyl group (organic acid) is preferably 0.1% by mass or more from the viewpoint of achieving a sufficient polishing rate, and is not considered to be excessively shallow. It is preferably 5% by mass or less.

[other ingredients]

The polishing liquid of the present invention may not detract from the present invention except for the components (A) to (D) which are essential components as described above, and the preferred component (E) as described above. The range of effects, and then use other known ingredients.

[surfactant]

The polishing liquid of the present invention may be used in combination with a surfactant other than the nonionic surfactant. The surfactant which can be used in combination includes an anionic surfactant and a cationic surfactant.

Specific examples of the "anionic surfactant" include, for example, mercaptobenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, cetylbenzenesulfonic acid, dodecylnaphthalene A compound such as sulfonic acid or tetradecylnaphthalenesulfonic acid.

Specific examples of the "cationic surfactant" include, for example, lauryl trimethylammonium, lauryl triethylammonium, stearyltrimethylammonium, palmityl trimethylammonium, octyltrimethylammonium. , a compound such as dodecylpyridinium, decylpyridinium, octylpyridinium or the like.

The anionic surfactant which can be used in the present invention includes a carboxylate, a sulfate salt, and a phosphate salt in addition to the sulfonate as described above.

More specifically, the "carboxylate" includes: soap, N-decylamino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxylate, deuterated peptide; "sulfate salt" system Including: sulfated oil, alkyl sulfate, alkyl ether sulfate, polyoxyethylene or polyoxypropylene alkyl aryl ether sulfate, alkyl decylamine sulfate; "phosphate salt" system includes: alkyl phosphate Salt, polyoxyethylene or polyoxypropylene alkyl aryl ether phosphate.

The amount of other surfactants which can be used in combination is preferably from 0.001 to 10 g, more preferably from 0.01 to 5 g, particularly preferably from 0.01 to 1 in 1 liter of the polishing liquid used for grinding. Gram. In other words, the amount of the surfactant to be added is preferably 0.01 g or more in order to obtain sufficient effect, and is preferably 1 g or less from the viewpoint of preventing a decrease in the CMP rate.

(oxidant) The polishing liquid of the present invention may contain a compound (oxidizing agent) capable of oxidizing a metal to be polished.

"Oxidant" includes, for example, hydrogen peroxide, peroxides, nitrates, iodates, periodates, hypochlorites, chlorites, chlorates, perchlorates, persulphates And dichromate, permanganate, ozone water, and silver (II) salt, iron (III) salt; among them, hydrogen peroxide is preferably used.

The "iron (III) salt" includes, for example, an inorganic iron (III) salt such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate or iron (III). An organic complex salt of iron (III) is used.

The amount of the oxidizing agent added can be adjusted according to the amount of shallow dishing in the initial stage of the barrier metal CMP. When the amount of shallowing of the barrier metal CMP is large, that is, in the barrier metal CMP, if it is not desired to excessively polish the wiring material, it is preferable to set the amount of the oxidizing agent to be small. If the amount of shallowing is very small and the wiring material is to be polished at a high speed, it is preferable to increase the amount of the oxidizing agent. As described above, since it is preferable to change the amount of the oxidizing agent which is desired according to the state of the shallow dish in the initial stage of the barrier metal CMP, it is preferably 0.01 in the polishing liquid used for polishing at 1 liter. Ears to 1 m, especially 005 to 0.6 m.

(pH adjuster) The pH of the slurry of the present invention must be from 2.5 to 5.0, preferably in the range of from 3.0 to 4.5. By controlling the pH of the polishing liquid within these ranges, the polishing rate of the interlayer insulating film can be remarkably adjusted.

To adjust the pH to a preferred range as described above, a base/acid or buffer is used. The pH of the polishing liquid of the present invention can exert superior effects in these ranges.

The "alkali/acid or buffer" includes organic ammonium hydroxide such as ammonia, ammonium hydroxide, and tetramethylammonium hydroxide, and an alkanolamine such as diethanolamine, triethanolamine or triisopropanolamine. "Non-metal alkaline agent"; "alkali metal hydroxide" such as sodium hydroxide, potassium hydroxide or lithium hydroxide; "mineral acid" such as nitric acid, sulfuric acid or phosphoric acid; "carbonate" such as sodium carbonate; "Phosphate" such as trisodium phosphate; borate, tetraborate, hydroxybenzoate, and the like. Particularly preferred alkaline agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

The amount of the alkali/acid or buffer added is as long as it is below the value of the conductivity as described above, and is used for grinding at 1 liter as long as it can maintain the pH in a preferred range. In the case of the slurry, it is preferably 0.0001 mol to 1.0 mol, more preferably 0.003 mol to 0.5 mol.

(chelating agent) The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening agent) as needed to reduce the adverse effects of the polyvalent metal ions to be mixed.

The "chelating agent" is a hard water softening agent or the like which is a general use of a calcium or magnesium precipitation preventing agent, and includes, for example, nitrogen triacetic acid, diethylene glycol triacetic acid, ethylenediamine tetraacetic acid, Nitrogen-N,N,N-trimethylenephosphonic acid, ethylenediamine-N,N,N',N'-tetramethylenesulfonic acid, trans-cyclohexanediaminetetraacetic acid, 1, 2-Diaminopropane tetraacetic acid, glycol ether diamine tetraacetic acid, ethylenediamine o-hydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS isomer), N-(2-carboxylate Ethyl)-L-aspartic acid, β-alanine diacetic acid, 2-phosphonic acid butane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N , N'-bis(2-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid, 1,2-dihydroxybenzene-4,6-disulfonic acid and the like.

The chelating agent may be used in combination of two or more kinds as needed.

The chelating agent is added in an amount as long as it is sufficient to block metal ions such as polyvalent metal ions, for example, in a slurry of 1 liter used for polishing, 0.0003 to 0.07 mol is added.

The polishing liquid of the present invention is suitable for polishing generally disposed between a wiring composed of a copper metal and/or a copper alloy and an interlayer insulating film, and is used for preventing copper. A diffusion barrier formed of a barrier metal material.

[blocking metal material]

The material of the barrier layer constituting the object to be polished of the polishing liquid of the present invention is usually a low-resistance metal material, and particularly preferably TiN, TiW, Ta, TaN, W, WN, Ru, and particularly preferably Ta and TaN.

[Interlayer insulating film]

The interlayer insulating film (insulating layer) to be polished by the polishing liquid of the present invention includes, for example, a material having a low dielectric constant of a relative dielectric constant of about 3.5 to 2.0 in addition to an interlayer insulating film which is generally used for TEOS or the like (for example, organic An interlayer insulating film of a polymer system, an SiOC system, an SiOF system or the like, which is generally simply referred to as a "Low-k film".

Specifically, materials for forming an interlayer insulating film having a low dielectric constant include HSG-R7 (Hitachi Chemical Co., Ltd.) and BLACK DIAMOND (US) for the SiOC system. Applied Materials, Inc.) and the like.

These Low-k films are usually located under the TEOS insulating film, and a barrier layer and metal wiring are formed on the TEOS insulating film.

The polishing liquid of the present invention is characterized in that it is suitable for polishing the barrier layer, and is suitable for a substrate having a laminated structure of a Low-k film and a TEOS insulating film, whereby the TEOS insulating film can be polished at a high speed and in the Low-k film. At the time of exposure, the polishing rate is suppressed, and polishing with excellent surface flatness and suppression of scratching can be achieved.

[wiring metal raw materials]

In the present invention, the object to be polished is preferably a wiring composed of a copper metal and/or a copper alloy, which is preferably used in a semiconductor device such as an LSI. In particular, the raw material of the wiring is preferably a copper alloy. Further, among the copper alloys, a copper alloy containing silver is preferable.

Further, the silver content of the copper alloy is preferably 40% by mass or less, more preferably 10% by mass or less, still more preferably 1% by mass or less, and the most excellent effect can be obtained from the content of 0.00001 to 0.1. Copper alloy in the range of %.

[The thickness of the wiring]

In the present invention, the object to be polished is preferably 0.15 in a half pitch (half pitch) if it is applied to, for example, a DRAM (Dynamic Random Access Memory) device system. The wiring of μm or less is more preferably 0.10 μm or less, further preferably 0.08 μm or less.

On the other hand, when the object to be polished is, for example, applied to an MPU (Micro Processing Unit) device system, it is preferable to have a wiring of 0.12 μm or less, more preferably 0.09 μm or less, still more preferably 0.07. Below μm.

The polishing liquid of the present invention as described above can exert an excellent effect on the object to be polished having such wiring.

[grinding method]

The polishing liquid of the present invention comprises: 1. a concentrated liquid, when used, diluted with water or an aqueous solution as a use liquid; 2. each component is prepared in the form of an aqueous solution as described in the following paragraph and Mixing, if necessary, add water to dilute as a use liquid; and 3. Modulate the use of liquid Three ways to wait.

In the polishing method using the polishing liquid of the present invention, the polishing liquid in any case is applicable.

This polishing method is a method in which a polishing liquid is supplied to a polishing pad on a polishing table to be in contact with a surface to be polished of the object to be polished, and the surface to be polished and the polishing pad are relatively moved.

Regarding the apparatus used for polishing, a holder having an object to be polished (for example, a wafer on which a film of a conductive material is formed, etc.) and a polishing pad (with changeable rotation) can be used. A number of motors, etc.) A general grinding device for a grinding platform. The polishing pad is not particularly limited, and a general nonwoven fabric, a foamed polyurethane, a porous fluororesin, or the like can be used. Further, the polishing conditions are not particularly limited, and the rotation speed of the polishing table is preferably a low-speed rotation in which the object is not blown out of 200 rpm or less. The pressing force of the object to be polished (the film to be polished) to the polishing pad is preferably 0.68 to 34.5 kPa, and if the polishing speed is to be uniform in the in-plane of the object to be polished and the flatness of the pattern, Good is 3.40 to 20.7 kPa.

During the grinding, the polishing liquid is continuously supplied to the polishing pad by a pump or the like.

After the object to be polished after the completion of the polishing is sufficiently washed in the running water, the water droplet adhering to the object to be polished is spun and dried using a rotary dryer or the like.

In the present invention, when the concentrate is diluted according to the method described above, the aqueous solution shown below can be used. The aqueous solution contains an oxidizing agent in advance At least one or more of an organic acid, an additive, and a surfactant, and therefore, the total amount of the component contained in the aqueous solution and the component contained in the concentrated solution for dilution should be the same as that used in the grinding. The components of the liquid (use liquid) are identical to each other.

As described above, when the concentrate is diluted with an aqueous solution, since the component which is not easily dissolved can be added as an aqueous solution and then mixed, a more concentrated concentrate can be prepared.

Further, when the concentrate is added to water or an aqueous solution to be diluted, the piping for supplying the concentrated polishing liquid and the piping for supplying the water or the aqueous solution are combined to be mixed on the way to mix the liquids, and the mixture is mixed. And the method of supplying the diluted slurry liquid to the polishing pad. When the concentrated liquid is mixed with water or an aqueous solution, the liquid can be passed through a narrow flow path to cause the liquids to collide with each other, and the glass tube or the like is filled in the pipe to repeatedly separate the flow and the flow of the liquid. The method and the method generally used for the method of providing a power rotary fin in a piping.

The supply rate of the polishing liquid is preferably from 10 to 1,000 ml/min, and more preferably from 170 to 800 ml/min, if the polishing speed is to be uniform in the in-plane of the polishing and the flatness of the pattern.

Further, when the concentrate is diluted with water or an aqueous solution or the like, the piping for supplying the polishing liquid and the piping for supplying the water or the aqueous solution are separately provided, and a specific amount is separately supplied to the polishing pad. The liquid is mixed while being polished by the relative movement of the polishing pad and the surface to be polished. In addition, it is also possible to use a certain amount of concentrated liquid and water or an aqueous solution in a container and mix it to supply the polishing pad. The method of grinding should be carried out by mixing the slurry.

In addition, in other grinding methods, there is a method in which the component to be contained in the polishing liquid is divided into at least two constituent components, and when it is used, it is diluted with water or an aqueous solution and supplied to the polishing pad on the polishing table to make it A method of performing polishing by contacting the surface to be polished and moving the surface to be polished relative to the polishing pad.

For example, the oxidizing agent may be the constituent component (A), the organic acid, the additive, the surfactant, and the water may be the constituent component (B), and when it is used, the constituent component (A) and the aqueous component or the aqueous solution may be used. The constituent (B) is diluted and used later.

In addition, the low solubility additive can be divided into two components (A) and (B), for example, an oxidizing agent, an additive, and a surfactant are used as a constituent (A), and an organic acid, an additive, a surfactant, and water are used. In order to constitute the component (B), when it is used, water or an aqueous solution is added to dilute the component (A) and the component (B) and use it.

In the case of the above examples, three kinds of pipes for separately supplying the component (A), the component (B), and the water or the aqueous solution are required, and the dilution mixing method is to connect the three pipes to one of the polishing pads. A method in which a pipe is mixed in a pipe. In this case, a method of connecting two types of pipes and then connecting one of the other pipes may be employed. Specifically, it is a mixture of a component containing a non-dissolvable additive and other constituent components, and a pipe of water or an aqueous solution is connected by lengthening the mixing channel to secure the dissolution time.

Other mixing methods include including the three types of piping as described above. Directly guided to the polishing pad, by mixing the polishing pad with the relative movement of the surface to be polished, or by mixing the three constituent components in one container and supplying the diluted polishing liquid to the polishing pad.

In the polishing method as described above, if one of the components containing the oxidizing agent is kept below 40 ° C, and the other constituent components are heated from room temperature to 100 ° C, such that a constituent component is mixed with other constituent components, or When water or an aqueous solution is diluted, the liquid temperature can be changed to 40 ° C or lower. Since it is a phenomenon in which the solubility is increased by using a higher temperature, whereby the solubility of the raw material having a low solubility of the polishing liquid can be improved, and therefore the method is a satisfactory method.

When the other constituent components are heated and dissolved in a range from room temperature to 100 ° C as described above, they are precipitated in the solution when the temperature is low, and therefore, when other components are used in a low temperature state, , the liquid must be pre-dissolved to dissolve the precipitated material. For this purpose, a means for supplying liquid by dissolving other constituent components of the raw material by heating, and a liquid for preliminarily stirring the liquid containing the precipitate, and then feeding the liquid and heating the piping to dissolve it may be employed. When the temperature of a constituent component containing the oxidizing agent is increased above 40 ° C, there is a concern that the oxidizing agent is decomposed, and therefore, the other constituents which are heated and the one containing the oxidizing agent are mixed. In the case of a component, it is preferably controlled to be 40 ° C or less.

As described above, in the present invention, the components of the polishing liquid can be supplied in two or more parts to the surface to be polished. In this case, it is preferably supplied as a component containing an oxide and a component containing an organic acid. In addition, it can also The slurry is supplied as a concentrate to separate the dilution water to the surface to be polished.

In the present invention, when a method of supplying the components of the polishing liquid into two or more parts to the surface to be polished is applied, the supply amount thereof indicates the total amount of supply from each of the pipes.

〔pad〕

The polishing pad for polishing which can be applied to the polishing method of the present invention may be a non-foamed structural pad or a foamed structural pad. In the former case, a hard synthetic resin block material such as a plastic plate is used as a mat. In the latter case, three types of independent foam (dry foaming), continuous foam (wet foaming), and two-layer composite (layered) may be used, and among them, particularly preferably Two-layer composite (layered system). Foaming can be in a homogeneous or heterogeneous form.

Further, it may be one containing abrasive grains (for example, ceria, cerium oxide, aluminum oxide, resin, etc.) generally used for polishing. Further, the hardness may be obtained from each having a soft or a hard one, but may be either one, and in the laminated layer, it is preferred to use a layer having a different hardness. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate, or the like. Further, processing on a surface in contact with the surface to be polished can be applied to a groove/hole/concentric groove/spiral groove.

[wafer]

The wafer on which the object to be polished of the CMP object is applied using the polishing liquid of the present invention preferably has a diameter of 200 mm or more, particularly preferably 300 mm or more. The present invention can significantly exert its effects on wafers having a diameter of 300 mm or more.

[grinding device]

The apparatus for performing the polishing using the polishing liquid of the present invention is not particularly limited and may be used, for example, by Mirra Mesa CMP, Reflexion CMP (American Applied Materials Co., Ltd.), FREX 200, FREX300 (manufactured by Ebara Seisakusho Co., Ltd.). NPS3301, NPS2301 (manufactured by Nikon Corp.); A-FP-310A, A-FP-210A (manufactured by Tokyo Precision Co., Ltd.); 2300 TERES (manufactured by Lam Research Co., Ltd.); Momentum (Speedfam IPEC, Manufacturing by Inc.).

"Embodiment"

Hereinafter, the present invention will be described in more detail by way of examples, but the invention is not limited thereto.

[Example 1]

A polishing liquid having the composition described below was prepared to carry out a grinding experiment.

<Composition (1)>

(evaluation method) In the polishing apparatus, a device "LGP-612" manufactured by Lapmaster SFF Corp. was used, and each wafer film shown below was polished while supplying a polishing liquid under the following conditions.

. Turntable revolutions: 90 rpm . Head rotation: 85 rpm . Grinding pressure: 13.79 kPa . Abrasive pad: Polotexpad manufactured by Rodel-Nitta Co. . Slurry supply speed: 200 ml / min

(Grinding speed evaluation: grinding object A) The object to be polished A was an 8-inch wafer on which a SiOC film (BLACK DIAMOND), a TEOS film, a Ta film, and a copper film were formed in this order on a tantalum substrate.

(Scratch evaluation: grinding object B) The polishing target B is patterned by using a Low-k film and a TEOS film which are produced by a CVD method by a photolithography step and a reactive ion etching step to form a width of 009 to 100 μm and a depth of 600. A trench and a connection hole are formed in the wiring of nm, and a Ta film having a thickness of 20 nm is formed by sputtering, and then a copper film having a thickness of 50 nm is formed by sputtering, and a total thickness of 1,000 nm is formed by electroplating. Obtained by copper film 8-inch wafer.

<grinding speed> The polishing rate is obtained by measuring the film thicknesses of the TEOS film (insulating film) and the SiOC film (Low-k film) before and after the CMP of the polishing target A for polishing rate evaluation, and calculating the following formula. The results are shown in Table 1:

Grinding speed /min) = (film thickness before grinding - film thickness after grinding) / grinding time.

<Scratch evaluation> The polishing object B for scratch evaluation as described above was polished by using the wafer as described above, and then polished to a SiOC film (the SiOC film was polished to 20 nm), and then the polished surface was washed with pure water. And dry it. The dried abrasive surface was observed with an optical microscope, and scratch evaluation was performed according to the following evaluation criteria. The first and second items are judged to be practically no problem. The results obtained are shown in Table 1.

- Evaluation benchmark - 1: At the end, it is observed that it will be a problematic scratch; 2: 1 to 2 observations in the wafer surface will cause a problem of scratching; 3: Many scratches will be observed in the wafer surface.

[Examples 2 to 44, and Comparative Examples 1 to 3]

The polishing liquid was prepared by changing the composition (1) of Example 1 to the composition shown in Tables 1 to 4 below, and the polishing test was carried out under the same polishing conditions as in Example 1. The results obtained are shown in Tables 1 to 4.

The (A) quaternary ammonium cation (specific cation) A-1 to A-46 as recited in Tables 1 to 4 above is intended to represent an exemplified compound as described above.

The details of the compounds referred to in Tables 1 to 4 above are as follows: (B) Corrosion inhibitors BTA: 1,2,3-benzotriazole DBTA: 5,6-dimethyl-1,2,3-benzotriazole DCEBTA: 1-(1,2-dicarboxyethyl)benzotriazole HEABTA: 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole HMBTA: 1-(hydroxymethyl)benzotriazole

The names of the (C) nonionic surfactant surfactants S-1 to S-7 compounds described in Tables 1 to 4 as described above are shown in Table 5 below. Further, the structures of S-10 to S-31 are as follows.

The shape of the (D) colloidal ceria C-1 to C-5 shown in Tables 1 to 4 above, the primary average particle diameter shown in the following Table 6, (E) the compound E having a carboxyl group will be described. The compound names of 1 to E-5 are shown in Table 7 below, respectively. Further, the colloidal cerium oxides shown in Table 6 below were all manufactured by Fuso Chemical Industry Co., Ltd.

As is apparent from Tables 1 to 4, when the polishing liquids of Examples 1 to 37 were used, the polishing rate of TEOS was higher than that of Comparative Examples 1 to 3, and the polishing speed of the SiOC insulating film belonging to the Low-k film was suppressed. And also has superior scratch performance.

On the other hand, in the polishing liquids of Comparative Examples 1 to 3, the polishing rate of TEOS, the polishing rate suppressing ability of the SiOC insulating film, and the scratching property were all inferior to those of the polishing liquid of the example.

Therefore, it is understood that the polishing liquid of the present invention has a superior TEOS polishing rate, and can effectively suppress the SiOC insulating film belonging to the Low-k film. Grinding speed, and also has superior scratch performance.

Claims (9)

A polishing liquid for chemical mechanical polishing in a planarization step of a semiconductor integrated circuit, and comprising a quaternary ammonium cation, a corrosion inhibitor, a nonionic surfactant, and a colloidal cerium oxide, and a pH It is from 2.5 to 5.0; the quaternary ammonium cation is a cation represented by the general formula (1) or the general formula (2) as follows: [In the formula (1), R ¹ to R ⁴ represent a methyl group, and R ⁵ to R ⁶ each independently represent an alkyl group having 1 to 20 carbon atoms, an alkenyl group, an alkynyl 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, and X represents an alkylene group having an alkyl group of 1 to 10, an alkenyl group, and an alkynyl group. , a cycloalkyl group, an aryl group, or a combination of two or more of these groups]; [In the formula (2), R ¹ to R ⁶ each independently represent an alkyl group having 1 to 20 carbon atoms Or alkenyl, alkynyl, cycloalkyl, aryl or aralkyl, two of R ¹ to R ⁶ may be bonded to each other to form a cyclic structure, and X represents a carbon number of from 1 to 10. An alkyl group, an alkenyl group, an alkynylene group, a cycloalkyl group, an aryl group, or a combination of two or more of these groups. The polishing liquid according to claim 1, wherein the nonionic surfactant is selected from the group consisting of an ether type nonionic surfactant, an ether ester type nonionic surfactant, and an ester type nonionic surfactant. One or more of the constituent ethnic groups. The polishing liquid according to claim 2, wherein the nonionic surfactant is a compound represented by the general formula (3) or the general formula (4) as described below: general formula (3) RO-(CH ₂ CH ₂ O) _n -H [In the formula (3), R represents an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms, and n represents a polyoxidation The number of vinyl bonds, and is an integer from 2 to 30]; [In the formula (4), R ¹ to R ⁴ each independently represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms, a, b, c , d, e, and f represent the number of bonds of the polyoxyethylene group, respectively, and a+b+c+d+e+f is 20 to 70]. A polishing liquid for chemical mechanical polishing in a planarization step of a semiconductor integrated circuit, and comprising a quaternary ammonium cation, a corrosion inhibitor, a nonionic surfactant, and a colloidal cerium oxide, and a pH It is from 2.5 to 5.0; the quaternary ammonium cation is a cation represented by the general formula (1) or the general formula (2) as follows: [In the general formula (1), the general formula (2), R ¹ to R ⁶ each independently represent an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aryl group having 1 to 20 carbon atoms, or An aralkyl group, two of R ¹ to R ⁶ may also be bonded to each other to form a cyclic structure, and X represents an alkylene group having 1 to 10 carbon atoms, an alkenyl group, an alkynylene group, and an anthracene group. a base, an aryl group, or a combination of two or more of these groups; the nonionic surfactant is selected from the group consisting of an ether type nonionic surfactant, an ether ester type nonionic surfactant, and an ester type nonionic One or more of the groups consisting of a surfactant; the nonionic surfactant is a compound represented by the following formula (4): [In the formula (4), R ¹ to R ⁴ each independently represent an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group or an aralkyl group having 2 to 30 carbon atoms, a, b, c , d, e, and f represent the number of bonds of the polyoxyethylene group, respectively, and a+b+c+d+e+f is 20 to 70]. The polishing liquid according to any one of claims 1 to 4, wherein the concentration of the colloidal cerium oxide is from 0.5 to 15% by mass based on the total mass of the polishing liquid. The slurry according to any one of claims 1 to 4, wherein the colloidal ceria has a primary average particle diameter in the range of 20 to 50 nm. The polishing liquid according to any one of claims 1 to 4, wherein the The corrosion inhibitor is selected from the group consisting of 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, tolyltriazole, 1-(1,2-dicarboxyl Ethyl)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) At least one compound of the group consisting of tolyltriazole and 1-(hydroxymethyl)benzotriazole. The polishing liquid according to any one of claims 1 to 4, which comprises a compound having a carboxyl group represented by the formula (5): a formula (5) R ⁷ -OR ⁸ -COOH [in the formula In (5), R ⁷ and R ⁸ each independently represent a hydrocarbon group, and R ⁷ and R ⁸ may be bonded to each other to form a cyclic structure]. A polishing method using the polishing liquid according to any one of claims 1 to 8.