TWI413678B - Polishing liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution containing solid abrasive grains to be used in barrier CMP for polishing a barrier layer made of a barrier metal material, which can obtain an excellent polishing speed for the barrier layer and can arbitrarily control the polishing speed of an insulating film. <P>SOLUTION: The polishing solution for polishing a barrier layer of a semiconductor integrated circuit contains a compound having colloidal silica having a surface indicating a positive &zeta; potential and a carboxylic group, a corrosion inhibitor and a surfactant, wherein pH is 2.5-5.0. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

Slurry

The present invention relates to a polishing liquid used in a manufacturing step of a semiconductor device, and more particularly to a polishing liquid suitable for polishing a barrier layer mainly composed of a barrier metal material 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), it is miniaturized. In recent years, high-speedization has been demanded by the miniaturization and stratification of wiring. Highly integrated. Various techniques such as Chemical Mechanical Polishing (hereinafter referred to as CMP) have been used as the technology for use therein. In the case where the surface of the film to be processed such as the interlayer insulating film is flattened, the formation of a plug, and the formation of a buried metal wiring are required, the CMP is performing the smoothing of the substrate or the excess metal at the time of wiring formation. Removal of the film or removal of excess barrier layers on the insulating film.

The general method of CMP is to attach a polishing pad to a circular polishing plate (platen), impregnate the polishing pad with a polishing liquid, and press the substrate surface (wafer) onto the pad to be inside. A state in which a predetermined pressure (grinding pressure) is applied to the surface, both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by mechanical friction generated.

When manufacturing a semiconductor device such as an LSI, a plurality of fine wirings are formed, and in the respective layers, when a metal wiring such as Cu is formed, diffusion of the wiring material into the interlayer insulating film is prevented, or adhesion of the wiring material is improved. For the purpose, a barrier metal in which Ta or TaN, Ti, TiN, or the like is formed in advance is performed.

In order to form the respective wiring layers, first, the metal film CMP (hereinafter referred to as a metal film CMP) for removing the excess wiring material that has been mounted by plating or the like is continuously performed in one or more stages, and then removed. CMP of a barrier metal material (barrier metal) exposed on the surface (hereinafter, referred to as barrier metal CMP). However, the metal film CMP causes a problem that the concave twisting of the so-called wiring portion is excessively polished, or further causing corrosion.

In order to reduce the concave twist grinding, in the barrier metal CMP performed after the metal film CMP, it is seeking to adjust the polishing speed of the metal wiring portion and the polishing speed of the metal portion of the barrier, and finally form a concave twist grinding or corrosion. A wiring layer with a small drop. In other words, 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, the concave portion of the wiring portion is rapidly ground or the like, or the resulting corrosion is caused. Therefore, it is desirable that the polishing rate of the barrier metal or the insulating film layer is moderately large. In addition to the advantages of improving the processing ability of the barrier metal CMP, in practice, concave twisting and polishing are often caused by the metal film CMP. For the above reasons, it is also desired to seek to relatively improve the polishing of the barrier metal or the insulating film layer. The aspect of speed.

A grinding solution for metals for CMP, generally comprising cerium particles (for example, alumina, ceria) and an oxidizing agent (for example, hydrogen peroxide, persulfuric acid). The basic mechanism is believed to be the oxidation of the metal surface by an oxidizing agent and the removal of its oxide film by rubbing.

However, when such a slurry containing solid cerium particles is used for CMP, In addition to the grinding damage (scratch), the phenomenon of polishing the entire polished surface more than necessary (thinning), the phenomenon of bending and polishing the metal surface on the disk (concave twisting) In addition to the insulator between the metal wirings, a phenomenon in which a plurality of wiring metal faces are bent on the disk (erosion) or the like occurs.

Further, by using a polishing liquid containing solid cerium particles, after the polishing, in order to remove the polishing liquid remaining on the semiconductor surface, the usual washing step is complicated, and further, the washed liquid is treated (waste In the liquid), there is a problem that it is necessary to settle and separate the cost surface of the solid ruthenium or the like.

For the polishing liquid containing such solid cerium particles, various studies as follows are being carried out.

For example, CMP abrasives and polishing methods for the purpose of high-speed polishing, which does not cause abrasive damage, are proposed (for example, see JP-A-2003-17446), polishing compositions for improving the cleanability in CMP, and polishing. In the method of the present invention, for example, the polishing composition for preventing the coagulation of the abrasive particles is obtained (for example, see JP-A-2000-84832).

However, even in the above-mentioned polishing liquid, there is a technique of realizing a high polishing rate when the polishing barrier layer is not obtained, and arbitrarily controlling the polishing rate of the interlayer insulating film.

[Patent Document 1] JP-A-2003-17446 [Patent Document 2] JP-A-2003-142435 Gazette [Patent Document 3] JP-A-2000-84832 Bulletin

An object of the present invention is to provide an abrasive which is a polishing liquid using solid cerium used for polishing a barrier CMP of a barrier layer composed of a barrier metal material, and which has an excellent polishing rate for the barrier layer, and The polishing speed of the insulating film is arbitrarily controlled.

As a result of intensive research, the inventors have found that the above problems can be solved by using the following polishing liquid to achieve the problem.

The polishing liquid of the present invention is used for polishing a polishing liquid of a barrier layer of a semiconductor integrated circuit, and is characterized by comprising a colloidal ceria having a positive zeta potential on the surface, a compound having a carboxyl group, a corrosion inhibitor, and a surfactant. A slurry with a pH of 2.5 to 5.0.

In the present invention, the surfactant is preferably a compound represented by the following general formula (1).

R-SO ₃ ^- General formula (1)

In the general formula (1), R represents a hydrocarbon group.

Further, in the present invention, the surfactant is preferably a compound represented by the following general formula (2).

In the general formula (2), R ¹ to R ^{4 each} independently represent a hydrocarbon group having 1 to 18 carbon atoms. However, R ¹ to R ^{4 are} not completely the same hydrocarbon group.

In the present invention, colloidal ceria having a positive zeta potential on the surface is a colloidal ceria which is a cationic compound adsorbed on the surface, and the cationic compound is represented by the following general formula (3). The compound is preferably a compound having a polyimine structure represented by the following general formula (4).

In the general formula (3), R ⁵ represents the completely identical hydrocarbon group having 1 to 18 carbon atoms. Further, in the general formula (4), R ⁶ and R ^{7 each} independently represent a hydrocarbon group. n represents an arbitrary integer of 1 or more.

In the present invention, the compound having a carboxyl group is preferably a compound represented by the following general formula (5), and it is preferred that the compound represented by the general formula (5) is selected from the group consisting of 2-furancarboxylic acid, 2,5- At least one of the group consisting of furan dicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid.

In the general formula (5), R ⁸ and R ^{9 each} independently represent a hydrocarbon group.

Further, it is preferred that the corrosion inhibitor of the present invention is selected from the group consisting of 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1-(1, Group of 2-dicarboxyethyl)benzotriazole, 1-[N,N-bis(hydroxyethyl)aminemethyl]benzotriazole, and 1-(hydroxymethyl)benzotriazole At least one compound.

The mechanism of the effects in the present invention is considered as follows.

In other words, a film type which is used as an interlayer insulating film (for example, BD (black diamond) or the like) has a low dielectric constant by substituting a hydroxyl group bonded to Si to form a hydrocarbon group. The interlayer insulating film is compared with an insulating film of an unsubstituted monomer (for example, TEOS (tetraethoxysilane or the like: a CAP layer used for the upper portion of the interlayer insulating film, etc.), and has a so-called inclusion amount in the film. The amount of the hydrocarbon group is such that the interlayer insulating film is relatively unsubstituted, and has the characteristics of (1) high hydrophobicity and (2) positive surface charge.

The basis of these conditions, that is, when a surfactant is added, the hydrophilic portion of the active agent is more likely to become a form in which the hydrophilic group of the surfactant concentrates on the surface thereof because the hydrophobic portion of the active agent is adsorbed on the surface of the interlayer insulating film. Therefore, it is considered that when an anionic surfactant is used, the surface of the interlayer insulating film changes to an anionic property, and when a cationic surfactant is used, the surface of the interlayer insulating film changes to a cationic property.

Therefore, according to the present invention, it is considered that an anionic property is used in the case of using colloidal ceria (abrasive particles) having a positive ZETTA (ζ) potential. In the case of the surfactant, the polishing particles and the interlayer insulating film are electrostatically adsorbed, and the polishing rate can be effectively increased. When the cationic surfactant is used, the polishing particles and the interlayer insulating film are electrostatically repelled, and the polishing can be effectively suppressed. speed.

According to the present invention, it is possible to provide an excellent polishing rate for the barrier layer, and to arbitrarily control the polishing rate of the insulating film.

Hereinafter, specific aspects of the 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 is characterized by comprising (A) a colloidal cerium oxide having a positive zeta potential on the surface, (B) a compound having a carboxyl group, and (C) The corrosion inhibitor and (D) surfactant are essential components, and the pH is 2.5 to 5.0, and if necessary, any component may be contained.

Each component contained in the polishing liquid of the present invention may be used singly or in combination of two or more.

The "polishing liquid" in the present invention means not only a polishing liquid used in polishing (that is, a polishing liquid diluted as necessary) but also a concentrated liquid of a polishing liquid. The concentrated liquid or the concentrated polishing liquid means a polishing liquid which is prepared by using a higher solute concentration than the polishing liquid used for polishing, and is used for polishing when it is used for polishing, by dilution with water or an aqueous solution. The dilution ratio is generally 1 to 20 volume multiples. In the present specification, "concentrated" and "concentrated liquid" are used in the conventional expressions indicating the meanings of "high concentration" and "high concentration liquid" in the use state, and are generally used in conjunction with physical concentration operations such as evaporation. Use different meanings to use.

Hereinafter, each component constituting the polishing liquid of the present invention will be described in detail.

[(A) Colloidal cerium oxide showing a positive zeta potential on the surface]

The polishing liquid of the present invention contains (A) colloidal cerium oxide whose surface exhibits a positive zeta potential as at least a part of the cerium particles.

The colloidal cerium oxide is not particularly limited as long as it exhibits a positive zeta potential, and is preferably a colloidal cerium oxide which is adsorbed on the surface by a cationic compound.

Therefore, in terms of colloidal cerium oxide which is modified or modified on the surface, it is preferred to contain colloidal cerium which is decomposed by hydrolysis of alkoxy decane without containing an impurity such as an alkali metal inside the particles. Further, colloidal cerium oxide produced by a method of removing alkali from an aqueous citric acid solution may be used, and in this case, the alkali metal remaining inside the particles is gradually eluted, which may be affected by the polishing performance. From such a viewpoint, it is preferred to use a hydrolyzed alkoxydecane as a raw material.

The particle size of the colloidal cerium oxide to be used as a raw material is appropriately selected depending on the purpose of use of the cerium particles, but is generally about 10 to 200 nm.

First, it is explained that (A) one of the colloidal ceria having a positive zeta potential on the surface, and the cationic compound adsorbed on the surface of the colloidal ceria.

The cationic compound used therein is preferably a compound represented by the following general formula (3) or a general formula (4), from the viewpoint of not impeding the polishing performance of other film species. A compound of the polyimine structure.

Hereinafter, a compound represented by the following general formula (3) and a compound having a polyimine structure represented by the following general formula (4) will be described.

In the above general formula (3), R ⁵ represents the completely identical hydrocarbon group having 1 to 18 carbon atoms.

Examples of the hydrocarbon group represented by R ⁵ include an alkyl group, an aryl group, a phenyl group and the like, and particularly preferably a linear alkyl group having 1 to 5 carbon atoms.

Specific examples of the compound represented by the general formula (3) include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetraammonium, and the like.

In the above general formula (4), R ⁶ and R ^{7 each} independently represent a hydrocarbon group, and preferably represent a hydrocarbon group having 1 to 10 carbon atoms.

R ^{6 is} preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, for example, an alkylene group having 1 to 10 carbon atoms.

R ⁷ represents a monovalent hydrocarbon group having 1 to 10 carbon atoms, for example, an alkyl group having 1 to 10 carbon atoms, an aryl group or an alkylphenyl group.

The hydrocarbon group represented by R ⁶ and R ⁷ may further have a substituent, and examples of the substituent which may be introduced include an alkyl group, a hydroxyl group, a carboxyl group and the like.

In the above general formula (4), n is an arbitrary integer of 1 or more.

That is, the compound having the polyimine structure represented by the general formula (4) is a polymer in which the above structural unit is n-bonded, and the weight average molecular weight is about 100 to 20,000, because it is from colloidal cerium oxide ( The viewpoint of the stability of the abrasive particles is preferred. Therefore, n which shows the number of repetitions of the structural unit in the general formula (4) is suitably determined from the substituent which the structural unit has, its molecular weight, and the above-mentioned preferable weight average molecular weight as a compound.

Specific examples of the compound having a polyimine structure represented by the general formula (4) include, for example, a polyethylenimine, a polyallylamine, and the like.

In order to adsorb the cationic compound as described above to the surface of the colloidal ceria, only the above compound and colloidal ceria may be mixed.

Thereby, the cationic compound having the above configuration is adsorbed on the surface of the colloidal ceria having a slight negative charge to obtain (A) colloidal ceria having a positive zeta potential on the surface.

In the present invention, (A) the zeta potential of the surface of the colloidal ceria can be measured by means of, for example, an electrophoresis method or an ultrasonic vibration method. For the specific measurement machine, DT-1200 (Luft Corporation, Japan) or the like can be used.

The surface of (A) in the polishing liquid of the present invention exhibits a content of colloidal cerium oxide having a positive zeta potential, and is a polishing liquid which is diluted with respect to the polishing liquid used at the time of polishing (that is, diluted with water or an aqueous solution). The following "the same applies to the polishing liquid used for polishing". The mass of the polishing liquid is preferably 1% by mass or more and 15% by mass or less, more preferably 3% by mass or more and 12% by mass or less, and particularly preferably 5% by mass or more. 12% by mass or less. That is, the (A) colloidal cerium oxide content is preferably from the viewpoint of polishing the barrier layer at a sufficient polishing rate. 1% by mass or more is preferably 15% by mass or less from the viewpoint of preserving stability.

In the polishing liquid of the present invention, it is possible to use (A) a ruthenium particle other than the colloidal cerium oxide having a positive zeta potential on the surface (A), even in this case, in the entire granule, (A) The content of the colloidal cerium oxide having a positive zeta potential on the surface is preferably 50% by mass or more, and particularly preferably 80% by mass or more. The cerium particles contained may also be all colloidal cerium oxide having a positive zeta potential on the surface of (A).

The polishing liquid of the present invention is exemplified by molten vermiculite, cerium oxide, aluminum oxide, titanium oxide, or the like, in combination with (A) a colloidal cerium which exhibits a positive zeta potential on the surface. The size of the combined ruthenium particles is equal to or higher than the colloidal cerium oxide having a positive zeta potential on the surface of (A), and is preferably 2 times or less.

[(B) Compound having a carboxyl group]

In the polishing liquid of the present invention, it is required to contain (B) a compound having a carboxyl group.

The compound having a carboxyl group is not particularly limited as long as it has at least one carboxyl group in the molecule. From the viewpoint of the polishing rate structure, it is preferred to select a compound represented by the following general formula (5).

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.

In the above general formula (5), R ⁸ and R ^{9 each} independently represent a hydrocarbon group, and preferably represent a hydrocarbon group having 1 to 10 carbon atoms. Further, the hydrocarbon group represented by R ⁸ and R ⁹ may further contain an oxygen atom in the chain.

R ⁸ is a monovalent hydrocarbon group, and is 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, or an aryloxy group. Wait.

R ⁹ is a divalent hydrocarbon group, and for example, an alkylene group having 1 to 10 carbon atoms (for example, a methylene group or a cycloalkylene group), an extended aryl group (for example, a phenylene group, etc.), an alkylene oxide group, or the like is preferable. .

The hydrocarbon group represented by R ⁸ and R ⁹ may further have a substituent, and examples of the substituent which may be introduced include, for example, an alkyl group having 1 to 3 carbon atoms, an aryl group, an alkoxy group, a carboxyl group and the like, and having a carboxyl group as a substituent. In the case of a substituent, the compound is composed of a plurality of carboxyl groups.

Further, R ⁸ and R ⁹ may be bonded to each other to form a ring structure.

Examples of the compound represented by the above general formula (5) include 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, Methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid, etc., preferably 2,5-furandicarboxylic acid, 2-tetrahydrofurancarboxylic acid, diglycolic acid, methoxyacetic acid, phenoxy The acetic acid, in particular, from the viewpoint of an increase in the polishing rate, is preferably 2-furancarboxylic acid, 2,5-furandicarboxylic acid or diglycolic acid.

In the polishing liquid of the present invention, the amount of the compound (B) having a carboxyl group (preferably, the compound represented by the general formula (5)) is preferably 0.1% by mass based on the mass of the polishing liquid used in the polishing. The above 5 mass% or less, more preferably 0.5 mass% or more and 2 mass% or less. That is, the content of such a compound having a carboxyl group is preferably from the viewpoint of achieving a sufficient polishing rate. From the viewpoint of not causing excessive concave twist grinding, it is preferably 5% by mass or less.

[(C) corrosion inhibitor]

In the polishing liquid of the present invention, a corrosion inhibitor which adsorbs on the surface to be polished to form a film to suppress corrosion of the metal surface is contained. In the case of the corrosion inhibitor of the present invention, it is preferred to have three or more nitrogen atoms in the molecule and an aromatic heterocyclic compound having a condensed ring structure. Among them, "three or more nitrogen atoms" are preferably atoms constituting a condensed ring, and among these aromatic heterocyclic compounds, benzotriazole and a derivative in which various substituents are introduced into the benzotriazole are preferred. Things.

As the corrosion inhibitor of the present invention, there are benzotriazole, 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1- (1,2-dicarboxyethyl)benzotriazole, 1-[N,N-bis(hydroxyethyl)aminemethyl]benzotriazole, 1-(hydroxymethyl)benzotriazole, etc. Of these, it is preferably selected from the group consisting of 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, and 1-(1,2-dicarboxyethyl)benzene. Triazole, 1-[N,N-bis(hydroxyethyl)aminemethyl]benzene triazole, and 1-(hydroxymethyl)benzotriazole.

The amount of the (C) 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 corrosion inhibitor added is preferably 0.01% by mass or more from the viewpoint of not expanding the concave twist grinding, and is preferably 0.2% by mass or less from the viewpoint of storage stability.

[(D) surfactant]

The polishing liquid of the present invention contains (D) a surfactant.

In the polishing liquid of the present invention, by adjusting the type and amount of the (D) surfactant, the polishing rate of the insulating layer can be controlled or the polishing rate of the insulating layer can be increased.

In particular, from the viewpoint of improving the polishing rate of the insulating layer, the compound represented by the following general formula (1) is preferably a general formula (2) from the viewpoint of controlling the polishing rate of the insulating layer. ) the compound represented.

R-SO ₃ ^- General formula (1)

In the above general formula (1), R represents a hydrocarbon group, and preferably represents a hydrocarbon group having 6 to 20 carbon atoms.

Specifically, for example, an alkyl group having 6 to 20 carbon atoms, an aryl group (for example, a phenyl group or a naphthyl group), and the like are preferable, and the alkyl group or the aryl group may further have a substituent such as an alkyl group.

Specific examples of the compound represented by the general formula (1) include, for example, undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid, hexadecylbenzenesulfonic acid, and dodecylnaphthalenesulfonic acid. a compound such as tetradecylnaphthalenesulfonic acid.

In the above general formula (2), R ¹ to R ^{4 each} independently represent a hydrocarbon group having 1 to 18 carbon atoms. However, R ¹ to R ⁴ are hydrocarbon groups which are not completely the same.

Examples of the hydrocarbon group represented by R ¹ to R ⁴ include an alkyl group, an aryl group, a phenyl group and the like, and particularly preferred are straight-chain and branched alkyl groups having 1 to 20 carbon atoms.

Further, two of R ¹ to R ⁴ may be bonded to each other to form a cyclic structure such as a pyridine structure, a pyrrolidine structure, a hexahydropyridine structure or a pyrrole structure.

Specific examples of the compound represented by the general formula (2) include, for example, lauryl trimethylammonium, lauryl triethylammonium, octadecyltrimethylammonium, hexadecyltrimethylammonium, octyltrimethylammonium, and dodecylpyridinium cation. a compound such as eleven pyridyl cation or octylpyridine cation.

Examples of the anionic surfactant other than the compound represented by the above general formula (1) include a carboxylate, a sulfate salt, and a phosphate salt.

More specifically, in terms of a carboxylate, a soap, an N-guanidine salt, a polyepoxyethyl or polyglycidyl alkyl ether carboxylate, or a deuterated peptide can be preferably used;

As the sulfate salt, a sulfated oil, an alkyl sulfate salt, an alkyl ether sulfate, a polyepoxyethyl or polyepoxypropyl alkyl decyl ether sulfate, an alkyl decylamine sulfate can be preferably used. As the phosphate salt, an alkyl phosphate salt, a polyepoxyethyl group or a polyepoxypropyl alkyl decyl ether phosphate can be preferably used.

(D) The amount of the surfactant to be added is preferably 0.001 to 10 g, preferably 0.01 to 5 g, particularly preferably 0.01 to 1 g, based on 1 L of the polishing liquid at the time of polishing. In other words, the amount of the surfactant to be added is preferably 0.01 g or more in terms of obtaining a sufficient effect, and is preferably 1 g or less from the viewpoint of preventing a decrease in the CMP rate.

In the polishing liquid of the present invention, in addition to the components (A) to (D) described above, other components may be appropriately added for the purpose. Explain these added ingredients.

[oxidant]

The polishing liquid of the present invention is preferably a compound (oxidizing agent) containing a metal which can oxidize the object to be polished.

Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, and heavy chromium. Acid salts, permanganates, ozone water, and silver (II) salts, iron (III) salts, among which hydrogen peroxide is particularly preferred.

In terms of iron (III) salt, iron is preferably used in addition to inorganic iron (III) salts such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate, and iron (III) bromide. The organic complex salt of (III).

The amount of the oxidizing agent added can be adjusted in accordance with the amount of concave twisting and polishing in the initial stage of the barrier CMP. When the amount of concave twisting and polishing in the initial stage of the barrier CMP is large, that is, when the wiring material is not much polished in the barrier CMP, it is desirable that the amount of the oxidizing agent is small, and the amount of grinding in the concave shape is small enough. When the wiring material is polished at a high speed, it is desirable to add a large amount of the oxidizing agent. Therefore, it is desirable to change the amount of the oxidizing agent to be changed in accordance with the concave state in the initial stage of the barrier CMP. Therefore, in the case of 1 L of the polishing liquid used for polishing, it is preferably 0.01 mol to 1 mol, particularly preferably 0.05 mol. 0.6 mol.

[pH adjuster]

The polishing liquid of the present invention requires a pH of 2.5 to 5.0, preferably a pH of 3.0 to 4.5. By controlling the pH of the polishing liquid in this range, the polishing rate adjustment of the interlayer insulating film can be performed more remarkably.

In order to adjust the pH to the above preferred range, a base/acid or a buffer is used. The polishing liquid of the present invention has a pH in this range and exhibits an excellent effect.

The alkali/acid or buffer may preferably be an organic ammonium hydroxide such as ammonia, ammonium hydroxide or tetramethylammonium hydroxide; or an alkanolamine such as diethanolamine, triethanolamine or triisopropanolamine. Non-metal alkaline agents such as 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; phosphoric acid such as trisodium phosphate Salt; borate, tetraborate, hydroxybenzoate, and the like. Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

When the amount of the alkali/acid or the buffer is less than or equal to the above-mentioned electrical conductivity value, it is preferably 0.0001 mol in 1 L of the polishing liquid used for polishing in order to maintain the pH in a preferred range. ~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 (i.e., a hard water softening agent) in order to reduce the adverse effects of the polyvalent metal ions to be mixed.

The chelating agent is a general hard water softening agent which is a calcium or magnesium precipitation preventing agent or a compound thereof, and examples thereof include nitrogen triacetic acid, diethylene triamine pentaacetic acid, ethylenediaminetetraacetic acid, N, N, N- Trimethylene phosphonic acid, ethylenediamine-N, N, N', N'-tetramethylene phosphonic acid, trans cyclohexanediaminetetraacetic acid, 1,2-diamine propane tetraacetic acid, glycol ether Amine tetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid (SS body), N-(2-carboxyaliphatic)-L-aspartic acid, β-alanine diacetic acid, 2-phospholidine-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 necessary.

The amount of the chelating agent to be added may be a sufficient amount for blocking the metal ions such as the polyvalent metal ions to be mixed, and for example, it may be added in an amount of 0.0003 mol to 0.07 mol in 1 L of the polishing liquid used for polishing.

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

[Bound Metal Materials]

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

[Interlayer insulating film]

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

Specifically, in terms of materials for forming a low dielectric interlayer insulating film, HSG-R7 (Hitachi Chemical Industry Co., Ltd.) and Obsidian (BLACK DIAMOND (Applied Materials, Inc.) are used in the SiOC system. ))Wait.

[Wiring metal raw materials]

In the present invention, the polishing system to be polished is preferably a semiconductor device such as an LSI (large scale integration), and preferably has a wiring made of copper metal and/or a copper alloy. particular Preferably, the raw material of the wiring is a copper alloy. Further, it is preferable to use a copper alloy containing silver in the copper alloy.

In addition, the content of silver contained in the copper alloy is preferably 40% by mass or less, particularly preferably 10% by mass or less, more preferably 1% by mass or less, and is exhibited in a copper alloy in a range of 0.00001 to 0.1% by mass. The best results.

[The thickness of the wiring]

In the present invention, in the case where the object to be polished is applied to, for example, a DRAM (dynamic random access memory) device series, wiring having a half pitch of 0.15 μm or less is preferable. Preferably, it is 0.10 μm or less, more preferably 0.08 μm or less.

Further, when the object to be polished is applied to, for example, an MPU (micro processing unit) device series, it is preferable to have a wiring of 0.12 μm or less, preferably 0.09 μm or less, and more preferably 0.07 μm or less.

The polishing liquid of the present invention exerts particularly excellent effects on the object to be polished having such wiring.

[grinding method]

The polishing liquid of the present invention is 1. It is a concentrated liquid, and when it is used, water or an aqueous solution is added to be diluted to become a use liquid; 2. The components are prepared in the form of an aqueous solution described in the following items, and they are mixed, and water is added as needed. The case where it is diluted to become a use liquid; 3. The case where it is used as a use liquid.

A polishing liquid according to the case of the polishing method using the polishing liquid of the present invention can also be applied.

The polishing method is a method in which a polishing pad for supplying a polishing liquid onto a polishing plate is brought into contact with a surface to be polished of the object to be polished to move the surface to be polished and the polishing pad. law.

For the apparatus for polishing, a fixing clip having a workpiece to be polished (for example, a wafer on which a film of a conductive material is formed), an adhesive polishing pad (a motor having a variable number of revolutions, etc.) can be used. A general grinding device for grinding a plate. As the polishing pad, a general nonwoven fabric, a foamed polyurethane, a porous fluororesin or the like can be used, and it is not particularly limited. Further, although the polishing conditions are not limited, the rotation speed of the polishing platen is preferably a low rotation of 200 rpm or less when the object to be polished does not fly out. It is preferable that the pressing pressure of the polishing pad having the object to be polished (the film to be polished) is 0.68 to 34.5 KPa, and it is more preferable to satisfy the uniformity in the surface of the object to be polished and the flatness of the pattern in order to satisfy the polishing rate. 3.40~20.7KPa.

While the material is being ground, the polishing liquid is continuously supplied to the polishing pad by a pump or the like.

After the polishing system after the polishing is sufficiently washed in the running water, it is dried by dropping a water droplet adhering to the object to be polished using a spin dryer or the like.

In the present invention, as in the method of the above 1, when the concentrate is diluted, an aqueous solution shown below can be used. The aqueous solution is a component containing at least one or more of an oxidizing agent, an organic acid, an additive, and a surfactant, and a component contained in the aqueous solution and a component contained in the diluted concentrated liquid are added as a component. The composition of the polishing liquid (use liquid) used.

Therefore, in the case where the concentrate is diluted with an aqueous solution, since the component which is difficult to dissolve can be blended in the form of an aqueous solution, a concentrated concentrate can be prepared.

Further, as a method of adding water or an aqueous solution to the concentrate to be diluted, there is a pipe for supplying the concentrated polishing liquid and a supply water or an aqueous solution on the way. The pipes are combined to be mixed, and a method of supplying the used liquid of the diluted slurry to the polishing pad is supplied. The method of mixing the concentrated liquid with water or an aqueous solution may be a method of colliding the mixed liquids through the narrow passage in a state where pressure is applied, and repeating the liquid flow recombination of the filler which blocks the gas pipe or the like in the piping. A method generally performed such as a method of providing a blade for power rotation in a pipe.

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

Further, as a method of diluting the concentrated liquid by water or an aqueous solution or the like, and separately polishing the piping for supplying the polishing liquid with the supply water or the aqueous solution, the predetermined amount of liquid is supplied to the polishing pad, and the polishing pad and the polishing pad are separately supplied. A method of mixing and grinding the relative motion of the abrasive surface. Further, a method in which the mixed polishing liquid is supplied to a polishing pad and is ground by adding and mixing a predetermined amount of the concentrated liquid with water or an aqueous solution in one container may be used.

In addition, in the other polishing method, it is possible to distinguish at least two kinds of components from all the components contained in the polishing liquid, and when they are used, they are diluted with water or an aqueous solution to be supplied to the polishing pad on the polishing plate, and are in contact with the surface to be polished. A grinding method for moving the surface to be polished relative to the polishing pad.

For example, an oxidizing agent is used as a component (A), and an organic acid, an additive, a surfactant, and water are used as a component (B), and when it is used, the component (A) and a component can be diluted by water or an aqueous solution. (B) to use.

Further, the additive having low solubility is composed of two kinds of constituent components (A) and (B), and for example, an oxidizing agent, an additive, and a surfactant are constituent components. (A) The organic acid, the additive, the surfactant, and water are used as the component (B), and when they are used, water or an aqueous solution is added, and the component (A) and the component (B) are diluted and used.

In the case of the above-described example, it is necessary to supply three kinds of pipes, which are the component (A), the component (B), and the water or the aqueous solution, and to mix and mix the three types of pipes to be one type of pipe to be supplied to the polishing pad. In this case, the method of mixing in the piping may be combined with the other piping from the combination of the two types of piping. Specifically, it is a method of mixing a pipe containing water or an aqueous solution from a mixture of a constituent component containing a hardly soluble additive and other constituent components, and extending the mixing route to ensure a dissolution time.

In the other mixing method, the three types of pipes are directly guided to the polishing pad as described above, and the three types of components are mixed by a relative movement of the polishing pad and the surface to be polished, or a mixture of three components is used in one container. The method of diluting the slurry on the polishing pad.

In the above polishing method, one type of constituent component containing an oxidizing agent is 40° C. or lower, and other constituent components are heated from room temperature to a range of 100° C., and when one type of constituent component and other constituent components are mixed, or water is added When the aqueous solution is diluted, the liquid temperature can be made 40 ° C or lower. This method is a preferred method for increasing the solubility of a raw material having a low solubility in a polishing liquid by utilizing a phenomenon in which the temperature is high and the solubility is high.

In the case where the raw material dissolved by heating the above-mentioned other constituent components from room temperature to 100 ° C is used, the temperature is lowered and precipitated in the solution. Therefore, when other components in a low temperature state are used, it is necessary to preheat the solution to dissolve the solution. Precipitated raw materials. Among them, other materials that have been heated and dissolved A means for constituting the liquid of the component; and means for transferring the liquid, heating the tube, and dissolving the liquid after stirring the liquid containing the precipitate. When there is a concern that the temperature of the other constituent component which has been heated or one of the constituent components including the oxidizing agent is 40° C. or higher and the oxidizing agent is decomposed, and the other constituent components which are heated and one constituent component containing the oxidizing agent are mixed. Preferably, it is carried out at 40 ° C or lower.

Therefore, in the present invention, the polishing liquid component may be divided into two or more components to be 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. Further, the polishing liquid may be a concentrated liquid and may be supplied to the surface to be polished in addition to the dilution water.

In the present invention, when the method of dividing the polishing liquid component into two or more components to be supplied to the surface to be polished is applied, the supply amount indicates the total amount of supply from each pipe.

[pad]

The polishing pad for polishing which is suitable for the polishing method of the present invention may be a non-foaming structural mat or a foamed structural mat. The former is a hard synthetic resin block such as a plastic plate. Further, the latter is a further independent foam (dry foaming system), a continuous foam (wet foaming system), and a two-layer composite (layered system), and particularly preferably a two-layer composite (layered system). . The foaming can be uniform or non-uniform.

Further, it may be one containing cerium particles generally used for grinding (for example, cerium oxide, cerium oxide, aluminum oxide, resin, etc.). Further, the individual hardness may be either soft or hard, and in the laminated system, it is preferred to use a different hardness in each layer. In terms of material, it is preferably non-woven fabric, artificial leather, polyamide, Polyurethane, polyester, polycarbonate, and the like. Further, processing such as lattice grooves/holes/concentric grooves/spiral grooves may be performed on the surface in contact with the surface to be polished.

[wafer]

The wafer to be polished by the polishing liquid in the present invention is preferably 200 mm or more in diameter, and particularly preferably 300 mm or more. When it is 300 mm or more, the effect of the present invention is remarkably exhibited.

[grinding device]

The apparatus for performing the polishing using the polishing liquid of the present invention is not particularly limited, and examples thereof include Mirra Mesa CMP, Reflexion CMP (Applied Material Company), FREX 200, FREX 300 (荏原株式会社), NPS3301, NPS2301 (Nippon), and A. - FP-310A, A-FP-210A (Tokyo Precision), 2300 TERES (Lam Research), Momentum (Speedfam IPEC), and the like.

[Examples]

In the following, the 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 shown below was prepared to carry out a polishing experiment.

<Composition (1)>

<ζ(ZETTA) potential measurement> The zeta potential of the surface of the colloidal ceria which exhibits a positive zeta potential on the surface of (A) of the obtained polishing liquid was measured under the following conditions. This result confirmed that the zeta (ZETTA) potential was 12 mV and showed a positive value. Among them, the zeta (ZETTA) potential was measured by the LT-1200 manufactured by Luft Corporation of Japan, and the polishing liquid of Example 1 was measured in a non-concentrated form.

(evaluation method) The apparatus "LGP-612" manufactured by Lapmaster Co., Ltd. was used as a polishing apparatus, and the slurry was supplied under the following conditions, and the various wafer films shown below were polished.

. Number of chuck revolutions: 64rpm . Grinding pad rotation: 65rpm . Grinding pressure: 13.79kPa . Grinding pad: IC1400 XY-K-Pad manufactured by Rodel Nitta Co., Ltd. . Grinding fluid supply speed: 200ml/min

(Grinding speed evaluation: grinding object) An 8-inch wafer on which a polishing target (Ta, TEOS, BD) is formed on a Si substrate is used as an object to be polished.

(Corrosion evaluation: grinding object) The TEOS (tetraethoxydecane) substrate is patterned by a lithography step and a reactive ion etching step to form a width of 0.09 to 100 μm. 600 nm wiring trench and connection hole, further, a Ta film having a thickness of 20 nm is formed by a sputtering method, and then a copper film having a thickness of 50 nm is formed by sputtering, and then a copper film having a total thickness of 1000 nm is formed by electroplating. The 8 吋 wafer is used as an object of polishing.

<grinding speed> The polishing rate was determined by measuring the film thicknesses of Ta (barrier layer), TEOS (insulating film), and BD (low dielectric constant insulating film) before and after CMP, and converted by the following formula.

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

The results obtained are shown in Table 1.

<Corrosion evaluation> For the pattern wafer which was completely exposed to Ta of the barrier metal material, the polishing liquid of Example 1 was used for the polishing for 60 seconds, and the line and the interval portion (line 9 μm, interval) were measured using a stylus type differential meter Dektak V320Si (manufactured by Veeco). Corrosion of 1 μm).

[Examples 2 to 45, and Comparative Examples 1 to 10]

The polishing liquid prepared in the composition shown in the following Tables 1 to 6 was used in the composition (1) of the first modification, and the polishing test was carried out under the same polishing conditions as in the first example. The results are shown in Tables 1 to 6.

Detailed information of the compounds referred to in Tables 1 to 6 above will be described below.

TBA: tetrabutylammonium nitrate [(2) cationic compound] TMA: tetramethylammonium nitrate [(2) cationic compound] TEA: tetraethylammonium nitrate [(2) cationic compound] PEI: polyethylenimine (weight average molecular weight 2000) [cationic compound] PPI: polyethylenimine (weight average molecular weight 3000) [(2) cationic Compound] BTA: 1,2,3-benzotriazole [(C) component] BS: undecylbenzenesulfonic acid [(D) component] DBS: Dodecylbenzenesulfonic acid [(D) component] TBS: tetradecylbenzenesulfonic acid [(D) component] HBS: Hexylbenzenesulfonic acid [(D) component] DNS: Dodecylnaphthalenesulfonic acid [(D) component] TNS: tetradecylnaphthalenesulfonic acid [(D) component] LTM: lauryl nitrate trimethylammonium [(D) component] LTE: Lauryl nitrate triethylammonium [(D) component] DP: Dodecyl pyridine cation [(D) component]

Further, the colloidal ceria PL3 and PL3H described in Tables 1 to 6 are both manufactured by Fuso Chemical Industry Co., Ltd., and the primary particle diameter and shape are as follows.

PL3: 35 nm (primary particle size), cocoon-shaped (shape) PL3H: 35 nm (primary particle size), aggregate (shape)

According to Tables 1 to 3, in the case of using the polishing liquids of Examples 1 to 30 Next, it was found that the Ta polishing rate was high, and compared with Comparative Examples 1 to 5, the polishing rate of the low dielectric constant insulating film (BD) was high. Therefore, in the polishing liquids of Examples 1 to 30, since the polishing rate of the insulating film having a low dielectric constant is extremely rapid, it is known that a film having a specific dielectric constant is formed, and it is desired to grind a low dielectric constant in a large amount. The case of an insulating film is very useful.

Further, the properties of the corrosion after polishing were not in any of Examples 1 to 30 and Comparative Examples 1 to 5.

According to Tables 4 to 6, in the case of using the polishing liquids of Examples 31 to 45, it was found that the Ta polishing rate was high, and compared with Comparative Examples 6 to 10, the low dielectric constant insulating film (BD) had a low polishing rate. . Therefore, in the polishing liquids of Examples 31 to 45, since the polishing rate of the insulating film having a low dielectric constant is very slow, it is known that the film is composed of a film containing a specific dielectric constant, and the low dielectric constant insulating is not polished. The case of the film (for example, the case where the end of the polishing is to be terminated on the surface of the insulating film having a low dielectric constant) is very useful.

Further, the corrosion performance after polishing, any of Examples 31 to 45 and Comparative Examples 6 to 10 was a value having no problem.

As described above, according to the present invention, by adjusting the composition of the polishing liquid, the Ta polishing rate is increased, and the polishing rate of the insulating film having a low dielectric constant can be arbitrarily controlled.

Claims (10)

A polishing liquid for polishing a barrier layer of a semiconductor integrated circuit, comprising: a colloidal ceria having a positive zeta potential on a surface, a compound having a carboxyl group, a corrosion inhibitor, and a surfactant; The pH is 2.5 to 5.0. The slurry according to claim 1, wherein the surfactant is a compound represented by the following general formula (1); R-SO ₃ ^- general formula (1) [In the general formula (1), R represents a hydrocarbon group ]. The slurry according to claim 1, wherein the surfactant is a compound represented by the following general formula (2); [In the general formula (2), R ¹ to R ^{4 each} independently represent a hydrocarbon group having 1 to 18 carbon atoms; however, R ¹ to R ^{4 are} not completely the same hydrocarbon group]. The slurry according to claim 1, wherein the colloidal ceria having a positive zeta potential is a compound represented by the following general formula (3), or a polyimine represented by the following general formula (4); a structured cationic compound adsorbed on the surface of colloidal cerium oxide; [In the general formula (3), R ⁵ represents a completely identical hydrocarbon group having 1 to 18 carbon atoms; and in the general formula (4), R ⁶ and R ^{7 each} independently represent a hydrocarbon group, and n represents an arbitrary integer of 1 or more] . The slurry according to claim 4, wherein the colloidal ceria having a positive zeta potential is a colloidal ceria adsorbed on the surface of the compound represented by the general formula (3). The polishing liquid according to claim 1, wherein the compound having a carboxyl group is a compound represented by the following general formula (5); R ⁸ -OR ⁹ -COOH General formula (5) [In general formula (5), R ⁸ and R ^{9 each} independently represent a hydrocarbon group]. The polishing liquid according to claim 6, wherein the compound represented by the general formula (5) is selected from the group consisting of 2-furancarboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, and 2-tetrahydrofurancarboxylate. Acid, oxidized diacetic acid At least one of the group consisting of acid), methoxyacetic acid, methoxyphenylacetic acid, and phenoxyacetic acid. The slurry of claim 1, wherein the corrosion inhibitor is selected from the group consisting of 1,2,3-benzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1 -(1,2-dicarboxyethyl)benzotriazole, 1-[N,N-bis(hydroxyethyl)aminemethyl]benzotriazole, and 1-(hydroxymethyl)benzotriazole At least one compound in the group. For example, the slurry of the first application of the patent scope, wherein the pH is 3.0 to 4.5. A polishing method comprising: supplying a polishing liquid according to any one of claims 1 to 9 to a polishing pad on a polishing plate; contacting the polishing pad with a surface to be polished of the object to be polished; The surface moves relative to the polishing pad.