JP2009081199A - Polishing solution and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution which is used in a method of manufacturing a semiconductor integrated circuit, achieved in the high polish rate of an insulating layer, and suppresses the generation of erosion. <P>SOLUTION: The polishing solution is used for chemical mechanical polishing in a step of planarizing a semiconductor integrated circuit having an insulating layer. The polishing solution contains (A) a cerium oxide particle, (B) a benzotriazol dielectric having at least one alkyl group, and (C) an acid. The (B) benzotriazol dielectric desirably has only an alkyl group as a substituent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter referred to as LSIs), higher density and higher integration are being promoted in order to achieve miniaturization and higher speed. Accordingly, in recent years, there has been an increasing demand for miniaturization and lamination of wiring.
When manufacturing semiconductor integrated circuits such as LSI, fine wiring is formed in multiple layers, and when forming metal wiring such as Cu in each layer, barrier metals such as Ta, TaN, Ti, TiN are formed in advance. It is common. The barrier layer is provided for the purpose of preventing the diffusion of the wiring material into the interlayer insulating film (hereinafter sometimes referred to as “insulating layer”) and improving the adhesion of the wiring material.

In this metal wiring formation, various techniques such as chemical mechanical polishing (hereinafter sometimes referred to as “CMP”) have been used.
This CMP is an indispensable technique when performing surface planarization of an insulating layer or the like, plug formation, formation of embedded metal wiring, and the like. CMP is used to smooth the substrate, remove excess metal thin films during wiring formation, and remove excess barrier layers.

  The metal polishing solution used for CMP generally contains abrasive grains (for example, alumina and silica) and an oxidizing agent (for example, hydrogen peroxide and persulfuric acid). It is considered that the basic mechanism is polishing by oxidizing the metal surface with an oxidizing agent and removing the oxide film with abrasive grains.

  A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the surface of the polishing pad with a polishing liquid, press the surface of the substrate (wafer) against the pad, In a state where pressure (polishing pressure) is applied, both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction.

In order to form each wiring layer, two steps of polishing are generally performed.
In the first stage polishing, the excess metal wiring material deposited by plating or the like is removed by CMP. The process of removing the excess metal wiring material from the metal film is hereinafter referred to as “metal film CMP”. The metal film CMP is performed in one or more stages.

In the second stage polishing, the barrier metal exposed on the surface by the first stage polishing is removed by CMP, and further, the surface of the insulating layer or the like is planarized. This polishing step is hereinafter referred to as “barrier metal CMP”. Barrier metal CMP is performed in one or more stages.
That is, in the barrier metal CMP, the metal wiring material and the barrier metal are simultaneously polished, and further, the metal wiring material and the insulating layer are simultaneously polished to flatten the surface.
At this time, if barrier metal CMP is performed using the polishing liquid containing solid abrasive grains, the wiring portion may be quickly polished, resulting in erosion.

Therefore, in the barrier metal CMP, it is required to adjust the polishing rate of the metal wiring part and the polishing rate of the barrier metal part or the insulating layer to finally form a wiring layer with few steps such as dishing and erosion. ing.
That is, it is desirable to increase the polishing rate of the insulating layer to the same level as the polishing rate of the metal wiring material so as not to cause dishing or erosion.

  In addition, as another problem, the use of a polishing liquid containing solid abrasive grains complicates the cleaning process normally performed to remove the polishing liquid remaining on the semiconductor surface after polishing. In order to treat the liquid (waste liquid), there is a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.

The following various studies have been made on the polishing liquid containing such solid abrasive grains.
For example, a CMP polishing agent and a polishing method (for example, refer to Patent Document 1) aiming at high-speed polishing with almost no polishing scratches generated, a polishing composition and a polishing method with improved cleaning performance in CMP (for example, , And Patent Document 2) and a polishing composition (see, for example, Patent Document 3) that prevents aggregation of abrasive grains have been proposed.
Further, as the chemical mechanical abrasive for planarizing the insulating film layer, a cerium oxide abrasive containing cerium oxide particles, a copolymer of ammonium acrylate and methyl acrylate, and water is disclosed (for example, (See Patent Document 4)

However, even with the above-described polishing liquid, the present situation is that a technique for realizing a high polishing rate and sufficiently suppressing the occurrence of erosion when polishing the insulating layer has not yet been obtained.
JP 2003-17446 A JP 2003-142435 A JP 2000-84832 A JP 2000-17195 A

  An object of the present invention is a polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit having an insulating layer, realizing a high polishing rate of the insulating layer, and An object of the present invention is to provide a polishing liquid and a polishing method that suppress the occurrence of erosion.

As a result of intensive studies, the present inventor has found that the above problem can be solved by using the following polishing liquid, and has achieved the object.
The polishing liquid of the present invention is a polishing liquid used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit having an insulating layer, and includes (A) cerium oxide particles and (B) a benzoic acid having at least one alkyl group. A polishing liquid containing a triazole derivative and (C) an acid.

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

In general formula (1), R < ¹ > -R < ⁵ > represents a hydrogen atom or an alkyl group each independently. However, at least one of R ^{1 to} R ⁵ is an alkyl group.
It is preferable that

  The polishing liquid of the present invention preferably further contains a quaternary ammonium cation having one or more quaternary nitrogen atoms in the molecule.

  The concentration of the (A) cerium oxide particles is preferably in the range of 0.05% by mass or more and 15% by mass or less with respect to the total mass of the polishing liquid, and the primary average particle of the (A) cerium oxide particles The diameter is preferably in the range of 10 nm to 1000 nm.

  In the present invention, the (C) acid is selected from the group consisting of oxalic acid, glycolic acid, lactic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, and derivatives thereof. It is preferable that it is at least one compound.

The polishing liquid of the present invention preferably further contains a water-soluble polymer, and in particular, a polymer containing a monomer having a carboxyl group as a basic structural unit or a salt thereof, or a copolymer containing these. .
The pH of the polishing liquid of the present invention is preferably 2 or more and 10 or less.

  Further, in the polishing method of the present invention, (A) a cerium oxide particle, (B) a benzotriazole derivative having at least one alkyl group, and (C) a polishing liquid containing an acid is used to mainly insulate a semiconductor integrated circuit. Polish the layer chemically and mechanically. At this time, it is preferable that the density | concentration of (A) cerium oxide particle is the range of 0.05 mass% or more and 15 mass% or less with respect to the total mass of polishing liquid.

  The polishing method of the present invention can be applied to the removal of the barrier metal in addition to being applicable to the planarization of the surface of the insulating layer. Here, the polishing method of the present invention can also be applied to general barrier metal polishing, but even when the barrier layer formed of Mn, Ti, Ru or derivatives thereof is polished, There is an effect.

  According to the present invention, a polishing liquid using solid abrasive grains used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit, realizing a high polishing rate of an insulating layer and generating erosion. A polishing liquid and a polishing method can be provided.

Hereinafter, specific embodiments of the present invention will be described.
The polishing liquid of the present invention is a polishing liquid used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit having an insulating layer, and includes (A) cerium oxide particles and (B) a benzoic acid having at least one alkyl group. It is characterized by containing a triazole derivative (hereinafter sometimes referred to as “benzotriazole derivative of the present invention”) and (C) an acid, and may further contain optional components as necessary.
Each component contained in the polishing liquid of the present invention may be used alone or in combination of two or more.

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

(A) Cerium oxide particles The polishing liquid of the present invention contains cerium oxide particles as abrasive grains. In general, cerium oxide particles are obtained by oxidizing a cerium compound of carbonate, nitrate, sulfate, or oxalate.

The primary average particle diameter of the cerium oxide particles is preferably 10 nm to 1000 nm, more preferably 10 nm to 80 nm, and still more preferably 20 nm to 60 nm.
In the present invention, the primary average particle diameter of the cerium oxide particles is obtained by observing cerium oxide dispersed in the slurry with an electron microscope (SEM), measuring the minimum particle diameter of 50 particles, and averaging these values. To do.
Since the polishing liquid of the present invention is used for substrate polishing related to semiconductor production, the content of alkali metals and halogens in the cerium oxide particles is preferably suppressed to 1 ppm or less.

  The method for producing the cerium oxide particles is not limited, but examples of the method for producing the cerium oxide powder from the cerium compound include firing or oxidation using hydrogen peroxide or the like. The firing temperature is preferably 350 ° C. or higher and 900 ° C. or lower, and is preferably used after being mechanically pulverized. As the pulverization method, a dry pulverization method such as a jet mill or a wet pulverization method such as a planetary bead mill is preferable.

  The addition amount of the abrasive is preferably 0.05% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, with respect to the total mass of the polishing liquid. The range of 1% by mass or more and 10% by mass or less is more preferable.

  The abrasive grains may contain particles other than cerium oxide particles. Examples of abrasive grains that can be used in combination include colloidal silica, fumed silica, ceria, alumina, and titania. However, even in that case, the content ratio of (A) cerium oxide particles in all abrasive grains is 50% by mass or more, and more preferably 80% by mass or more. All of the contained abrasive grains may be (A) cerium oxide particles.

(B) Benzotriazole derivative of the present invention The benzotriazole derivative of the present invention is a benzotriazole derivative having one or more alkyl groups as a substituent. The benzotriazole derivative of the present invention is a so-called corrosion inhibitor and adsorbs on the surface to be polished to form a film, thereby controlling the corrosion of the metal surface.

In particular, since the benzotriazole derivative of the present invention has at least one alkyl group, sufficient corrosion suppression of the metal wiring is performed, and this metal wiring suppresses excessive polishing of the insulating layer, thereby suppressing the occurrence of erosion. It is presumed that
Further, by combining the benzotriazole derivative of the present invention with cerium oxide as an abrasive grain, a sufficient polishing rate in the field part can be achieved, and the field part and the space part are polished by a synergistic effect with the above result. As a result of the speed approaching constant speed, it is presumed that the effect of the present invention has been achieved.
However, the present invention is not limited by the above estimation.

  The addition amount of the benzotriazole derivative of the present invention is 0.001% by mass or more and 0.3% with respect to the mass of the polishing liquid used for polishing, from the viewpoint of sufficiently suppressing the corrosion of the metal wiring. % By mass or less is preferable, and 0.01% by mass or more and 0.3% by mass or less is more preferable.

  The benzotriazole derivative of the present invention may have other substituents as long as it has one or more alkyl groups as substituents. Among them, a benzotriazole derivative represented by the following general formula (1) having only an alkyl group as a substituent is preferable.

In general formula (1), R < ¹ > -R < ⁵ > represents a hydrogen atom or an alkyl group each independently. However, at least one of R ^{1 to} R ⁵ is an alkyl group.

The alkyl group represented by R ^{1 to} R ⁵ may be linear, branched or cyclic, but is preferably a linear alkyl group.
The alkyl group represented by R ^{1 to} R ⁵ is preferably an alkyl group having 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 5 carbon atoms, and still more preferably an alkyl group having 1 to 3 carbon atoms.

Alkyl group represented by R ¹ to R ⁵ may further have a substituent, and examples of such substituents include a halogen atom (fluorine atom, chlorine atom, bromine atom, or iodine atom), an alkyl group (It is a linear, branched or cyclic alkyl group, and may be a polycyclic alkyl group such as a bicycloalkyl group or an active methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group ( Any position may be substituted), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group (the carbamoyl group having a substituent includes, for example, N-hydroxycarbamoyl group, N-acylcarbamoyl group) Group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfa Ylcarbamoyl group), carbazoyl group, carboxy group or salt thereof, oxalyl group, oxamoyl group, cyano group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (a group repeatedly containing ethyleneoxy group or propyleneoxy group unit) Including), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group , Sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydride Dino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, quaternized nitrogen atom A heterocyclic group (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic ring) thio group, (alkyl, aryl, or heterocyclic ring) ) Dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group, sulfamoyl group (the sulfamoyl group having a substituent includes, for example, N-acylsulfamoyl group, N-sulfonylsulfa Moyl group), phosphino group, phosphinyl group Phosphinyloxy group, phosphinylamino group, silyl group and the like. From the viewpoint of effectively suppressing corrosion of metal wiring, an alkyl group having no substituent is preferable.

Therefore, the alkyl group represented by R ^{1 to} R ⁵ is particularly preferably a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a cyclohexyl group, and the like. , A propyl group and a butyl group are preferable.

The number of alkyl groups contained in the benzotriazole derivative of the present invention is not particularly limited as long as it is 1 or more, but is preferably 1 to 3, more preferably 1 to 2.
In the benzotriazole derivative of the present invention, the position substituted with an alkyl group is not particularly limited, but when the number of alkyl groups is 3, R ¹ , R ³ and R ⁴ are preferably alkyl groups, R ¹ and R ³ , or R ³ and R ⁴ are preferably alkyl groups when the number of is 2, and when the number of alkyl groups is 1, R ¹ or R ³ is an alkyl group Is preferred.

  Specific examples of the (B) benzotriazole derivative of the present invention are shown below, but the present invention is not limited thereto.

The polishing liquid of the present invention can contain other azole derivatives in combination with the benzotriazole derivative of the present invention.
The content of the benzotriazole of the present invention relative to the total azole in the polishing liquid when used for polishing is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, More preferably, it is 80 mass%-100 mass%.

  Examples of the other azole derivatives include benzotriazole, aminobenzotriazole, alkoxybenzotriazole, tolyltriazole, 1- (1,2-dicarboxyethyl) tolyltriazole, 1- [N, N-bis having no substituent. In addition to benzotriazole derivatives such as (hydroxyethyl) aminomethyl] tolyltriazole, the nuclei such as imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole and the like are generally known as well-known. Corrosion inhibitors and derivatives thereof may be used, and among them, benzotriazole, aminobenzotriazole, alkoxybenzotriazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, which have no substituent, may be used. More preferred.

(C) Acid The polishing liquid of the present invention contains an acid. The acid has an action of promoting oxidation, adjusting pH, and buffering agent. It may be an organic acid or an inorganic acid, and preferably contains at least an organic acid.

As an organic acid in this invention, what was chosen from the following groups is preferable.
That is, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methyl Hexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, apple Examples thereof include acids, tartaric acid, citric acid, lactic acid, and salts thereof such as ammonium salts and alkali metal salts, sulfuric acid, nitric acid, ammonia, ammonium salts, and mixtures thereof.

  Among these, oxalic acid, glycolic acid, lactic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, apples can be effectively suppressed while maintaining a practical CMP rate. Preference is given to at least one compound selected from the group consisting of acids, tartaric acid, citric acid and the like and derivatives thereof.

Preferred examples of the organic acid in the present invention include amino acids.
As this amino acid and the like, water-soluble ones are preferable, and those selected from the following groups are more suitable.
That is, for example, glycine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L-proline, sarcosine, L-ornithine, L-lysine, taurine, L-serine, L-threonine, L-allothreonine, L-homoserine, L-tyrosine, 3,5-diiodo-L-tyrosine, β- ( 3,4-dihydroxyphenyl) -L-alanine, L-thyroxine, 4-hydroxy-L-proline, L-cystine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L-cystine, L- Cysteic acid, L-aspartic acid, L-glutamic acid, S- (carboxymethyl) -L-cysteine, 4- Aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L-histidine, 1-methyl-L-histidine It is desirable to contain at least one of amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine.

  The amount of the organic acid added is preferably 0.0005 mol to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the addition amount of the organic acid is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

  Preferred examples of the inorganic acid include inorganic acids such as nitric acid, sulfuric acid and phosphoric acid, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, borates, tetraborate and hydroxybenzoates. be able to. A particularly preferred inorganic acid is nitric acid.

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

(D) Quaternary ammonium cation In the polishing liquid of the present invention, as a preferred combination component, (D) a quaternary ammonium cation having one or more quaternary nitrogen atoms in the molecule (hereinafter simply referred to as “specific cation” or “fourth”). May be referred to as “ammonium cation”).

Although the action of the quaternary ammonium cation is not clear, it is presumed as follows.
That is, it is considered that the interaction between the abrasive particles and the surface to be polished is strengthened by the adsorption of the quaternary ammonium cations in the polishing liquid to the surface of the abrasive particles. More specifically, it is considered that the quaternary ammonium cation relaxes the repulsive force between the abrasive particles whose surface is negatively charged and the surface to be polished whose surface is negatively charged. As a result, it is considered that the physical action (physical scratch removing action) between the abrasive particles and the surface to be polished becomes strong, and the polishing rate for each film type is improved.

  The quaternary ammonium cation in the present invention is not particularly limited as long as it has a structure containing one or more quaternary nitrogens in the molecular structure. Especially, it is preferable that it is a cation represented by following General formula (2) or General formula (3) from a viewpoint of achieving the improvement of sufficient polishing rate.

In the general formula (2) and general formula (3), R ^{1 to} R ⁶ each independently represents an alkyl group having 1 to 20 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, Two of R ^{1 to} R ⁶ may be bonded to each other to form a cyclic structure.

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

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

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

X in the general formula (3) represents an alkylene group having 1 to 10 carbon atoms, an alkenylene group, a cycloalkylene group, an arylene group, or a group obtained by combining two or more of these groups.
In addition to the above organic linking group, the linking group represented by X includes —S—, —S (═O) ₂ —, —O—, —C (═O) — in the chain. May be included.

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

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

  Hereinafter, although the specific example [Exemplary compound (A1)-(A46)] of the quaternary ammonium cation (specific cation) in this invention is shown, this invention is not limited to these.

  Among the above-mentioned (D) quaternary ammonium cations (specific cations), A2, A8, A12, A16, A21, A22, A36, A37, and A46 are preferable from the viewpoint of dispersion stability in the polishing liquid.

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

  The amount of (D) quaternary ammonium cation (specific cation) added in the present invention is the polishing liquid used for polishing (that is, the diluted polishing liquid when diluted with water or an aqueous solution. "The polishing liquid when doing this" is also in agreement.) Is preferably 0.0001% by mass or more and 1% by mass or less, and more preferably 0.0001% by mass or more and 0.3% by mass or less. That is, the amount of the specific cation added is preferably 0.0001% by mass or more from the viewpoint of sufficiently improving the polishing rate, and is preferably 1% by mass or less from the viewpoint of sufficient slurry stability.

  The (D) quaternary ammonium cation (specific cation) according to the present invention may be only one type, or two or more different types may be used in combination.

(E) Water-soluble polymer The polishing liquid of the present invention can contain a water-soluble polymer as a preferred combination component.
The water-soluble polymer is preferably a polymer having a carboxyl group-containing monomer as a basic structural unit or a salt thereof, or a copolymer containing them. Specifically, polyacrylic acid and salts thereof and copolymers containing them, polymethacrylic acid and salts thereof and copolymers containing them, polyamic acid and salts thereof and copolymers containing them, polymaleic acid and polyitacon Examples thereof include polycarboxylic acids such as acid, polyfumaric acid, poly (p-styrenecarboxylic acid), and polyglyoxylic acid and salts thereof, and copolymers containing them. Furthermore, vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein can be mentioned.

  However, if the object to be polished is a silicon substrate for a semiconductor integrated circuit or the like, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable, so if the water-soluble polymer is an acid, use it as an acid. Or the ammonium salt is preferably used.

(E) Among water-soluble polymers, among them, polyacrylic acid, polymethacrylic acid, polymaleic acid, polyacrylamide, polyacrylic acid ammonium salt, polyvinyl alcohol, polo vinyl pyrrolidone, polyethylene glycol, and co-polymer containing these Polymers and polyoxyethylene polyoxypropylene block polymers are more preferred, and polyacrylic acid, polymethacrylic acid, polymaleic acid, polyacrylamide, and copolymers containing these are even more preferred.
Suitable copolymers include polyacrylic acid-polymethacrylic acid copolymers, polyacrylic acid-polyacrylamide copolymers, and the like.

  (E) The total amount of the water-soluble polymer added is preferably 0.001 g to 10 g, more preferably 0.01 g to 5 g, in 1 L of a polishing liquid used for polishing. It is especially preferable to set it as 1g-3g. That is, the amount of the water-soluble polymer added is preferably 0.001 g or more for obtaining a sufficient effect, and preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered.

  (E) As a weight average molecular weight of water-soluble polymer, 500-100000 are preferable, and 2000-50000 are especially preferable.

  The (E) water-soluble polymer according to the present invention may be only one type, or two or more different types may be used in combination.

  Further, the content ratio of (E) the water-soluble polymer and (A) cerium oxide is preferably 0.0001: 1 to 1: 0.001 in terms of mass ratio, and 0.001: 1-1. : 0.01 is more preferable, and 0.005: 1 to 1: 0.1 is particularly preferable.

(F) Surfactant In the polishing liquid of the present invention, a surfactant can be used in combination. Examples of the surfactant that can be used in combination include an anionic surfactant and a cationic surfactant.

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

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

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

The total amount of the surfactant added is preferably 0.001 to 10 g, more preferably 0.01 to 5 g in 1 liter of polishing liquid when used for polishing. It is particularly preferable that That is, the addition amount of the surfactant is preferably 0.01 g or more for obtaining a sufficient effect, and preferably 1 g or less from the viewpoint of preventing the CMP rate from being lowered.
One type of surfactant may be used alone, or two or more types may be used in combination.

[Other ingredients]
In the polishing liquid of the present invention, in addition to the above-mentioned essential components (A) to (C) and the preferred combined components (D) to (F), the scope of the present invention is not impaired. In addition, other known components can be used in combination.

(PH adjuster)
The polishing liquid of the present invention is preferably in the range of pH 2 to 10, more preferably in the range of pH 2 to 7, and still more preferably in the range of pH 2 to 5. By controlling the pH of the polishing liquid within this range, it is possible to adjust the polishing rate of the insulating layer more precisely.
In order to adjust the pH to the above preferable range, an alkali or a buffering agent can be used in addition to the above-mentioned acid.

Examples of the alkali or buffer include non-metallic alkaline agents such as organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, alkanolamines such as diethanolamine, triethanolamine and triisopropanolamine, water Preferable examples include alkali metal hydroxides such as sodium oxide, potassium hydroxide and lithium hydroxide.
Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

  The addition amount of the alkali or the buffer may be an amount that can maintain the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the polishing liquid used for polishing. It is more preferable to set it as 003 mol-0.5 mol.

(Chelating agent)
The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening agent) as necessary in order to reduce adverse effects such as mixed polyvalent metal ions.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as nitrilotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, N, N, N-trimethylenephosphonic acid. , Ethylenediamine-N, N, N ′, N′-tetramethylenesulfonic acid, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, ethylenediamine disuccinic acid ( SS form), N- (2-carboxylateethyl) -L-aspartic acid, β-alanine diacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, N , N′-bis (2-hydroxyben Le) ethylenediamine -N, N'-diacetic acid, 1,2-dihydroxy-4,6-disulfonic acid.

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

(Oxidant)
The polishing liquid of the present invention may contain a compound (oxidant) capable of oxidizing the metal to be polished.
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt.

  Examples of the iron (III) salt include iron (III) in addition to inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III) and iron bromide (III). Organic complex salts are preferably used.

  When an organic complex salt of iron (III) is used, examples of the complex-forming compound constituting the iron (III) complex salt include acetic acid, citric acid, oxalic acid, salicylic acid, diethyldithiocarbamic acid, succinic acid, tartaric acid, glycolic acid, glycine , Alanine, aspartic acid, thioglycolic acid, ethylenediamine, trimethylenediamine, diethylene glycol, triethylene glycol, 1,2-ethanedithiol, malonic acid, glutaric acid, 3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid, 3 Aminopolycarboxylic acid and its salt are mentioned other than -hydroxy salicylic acid, 3,5-dihydroxy salicylic acid, gallic acid, benzoic acid, maleic acid, etc. and these salts.

  Examples of aminopolycarboxylic acids and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, , 2-Diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylate ethyl) ) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, cyclohexanediaminetetraacetic acid, iminodiacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine 1-N, N′-diacetic acid, ethylenediamine orthohydroxyphenylacetic acid, N, N-bis (2-hydroxybenzidine ) Ethylenediamine -N, it includes and salts thereof such as N- diacetic acid. The kind of the counter salt is preferably an alkali metal salt or an ammonium salt, and particularly preferably an ammonium salt.

  Among these oxidizing agents, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and iron (III) organic complex salts are preferred, and iron (III) organic complex salts are preferred. Complex forming compounds include citric acid, tartaric acid, aminopolycarboxylic acid (specifically, ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N′-disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- ( Carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).

  Further, as an oxidizing agent, hydrogen peroxide, persulfate, and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, A complex of N′-tetraacetic acid and ethylenediamine disuccinic acid (SS form) is most preferred.

  The oxidizing agent is preferably used by mixing with a composition containing other components other than the oxidizing agent when polishing using a polishing liquid. The timing of mixing the oxidizing agent is preferably within 1 hour immediately before using the polishing liquid, more preferably within 5 minutes, and particularly preferably, a mixer is provided immediately before the polishing liquid is supplied by the polishing apparatus. Mixing within 5 seconds immediately before feeding to the polishing surface.

In the above-described barrier CMP, if the wiring material is not to be polished much, it is desirable to add a small amount of oxidizing agent. If the amount of dishing is sufficiently small and the wiring material is to be polished at high speed, the addition of an oxidizing agent is desirable. It is desirable to increase the amount.
Thus, since it is desirable to change the addition amount of the oxidizing agent depending on the dishing situation at the initial stage of the barrier CMP, it is preferable that the amount is 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. It is especially preferable to set it as 05 mol-0.6 mol.

[Use of polishing liquid]
The polishing liquid of the present invention is suitable for polishing an insulating layer because it can polish an insulating layer of a semiconductor integrated circuit at high speed. However, the present invention can also be applied to polishing a barrier layer existing between the metal wiring and the insulating layer. Therefore, the present invention can also be suitably applied to the case where the barrier layer polishing and the insulating layer polishing are performed in a single step by barrier CMP.
In the polishing of the insulating layer, the insulating layer is mainly polished. At the same time, the metal wiring is also polished, or the barrier layer is also polished to flatten the surface. Therefore, the present invention does not exclude polishing of metal wiring and barrier layers.

[Barrier metal material]
As a material constituting the barrier layer, a low-resistance metal material is generally preferable, and TiN, TiW, Ta, TaN, W, WN, Ru, and the like are preferably used, and among these, Ta and TaN are preferably used. In addition to these Ta-based metal materials, the polishing liquid of the present invention can also be applied to barrier layers formed of Mn, Ti, Ru, or derivatives thereof.

[Insulation layer]
As an insulating layer to be polished by the polishing liquid of the present invention, in addition to a commonly used insulating layer such as TEOS, for example, a low dielectric constant material having a relative dielectric constant of about 3.5 to 2.0 (for example, an organic polymer) And an insulating layer including a normal system, abbreviated as a Low-k film).
Specifically, HSG-R7 (Hitachi Chemical Industry), BLACKDIAMOND (Applied Materials, Inc), SilK (The Dow Chemical Co), Aurora (Japan M.) and Coral (Novellus Systems, Inc.).
Such a Low-k film is usually located under the TEOS insulating film, and a barrier layer and a metal wiring are formed on the TEOS insulating film.

[Raw metal materials]
In the present invention, it is preferable that the object to be polished has a wiring made of copper metal and / or copper alloy as applied to a semiconductor integrated circuit such as LSI. In particular, a copper alloy is preferable as a raw material for the wiring. Furthermore, the copper alloy containing silver is preferable among copper alloys.
In addition, the silver content contained in the copper alloy is preferably 40% by mass or less, particularly 10% by mass or less, more preferably 1% by mass or less, and a copper alloy in the range of 0.00001 to 0.1% by mass. The most excellent effect is exhibited.

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

[Polishing method]
The polishing liquid of the present invention is (1) a concentrated liquid, and when used to dilute by adding water or an aqueous solution, (2) each component is prepared in the form of an aqueous solution described in the next section. When these are mixed and diluted with water as necessary to obtain a use solution, (3) the use solution may be prepared.
The polishing liquid in any case can be applied to the polishing method using the polishing liquid of the present invention.
This polishing method is a method in which a polishing liquid is supplied to a polishing pad on a polishing surface plate, brought into contact with the surface to be polished of the object to be polished, and the surface to be polished and the polishing pad are moved relative to each other.

As an apparatus used for polishing, a holder for holding an object to be polished (for example, a wafer on which a conductive material film is formed) having a surface to be polished and a polishing pad are attached (a motor capable of changing the number of rotations). Etc.) and a general polishing apparatus having a polishing surface plate. As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation.
The polishing conditions are not limited, but the rotation speed of the polishing surface plate is preferably a low rotation of 200 rpm or less so that the object to be polished does not pop out. The pressing pressure of the object having the surface to be polished (film to be polished) against the polishing pad is preferably 0.68 to 34.5 KPa, the in-plane uniformity of the object to be polished at the polishing rate and the flatness of the pattern In order to satisfy the properties, it is more preferably 3.40 to 20.7 KPa.

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

In the present invention, when diluting the concentrate as in the method (1), the following aqueous solutions can be used. The aqueous solution is water containing at least one of (A) cerium oxide particles, (B) a benzotriazole derivative having at least one alkyl group, and (C) an acid in advance. The component obtained by adding up the components contained in the diluted concentrate and the components contained in the concentrated liquid to be diluted becomes a component of the polishing liquid (use liquid) used for polishing.
Thus, when the concentrate is diluted with an aqueous solution and used, components that are difficult to dissolve can be added later in the form of an aqueous solution, so that a more concentrated concentrate can be prepared.

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

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

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

In addition, as another polishing method, the component to be contained in the polishing liquid is divided into at least two components, and when these are used, water or an aqueous solution is added and diluted and supplied to the polishing pad on the polishing platen Then, there is a method in which the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished for polishing.
For example, the oxidizing agent is the component (A), the acid, other additives and water are the component (B), and the component (A) and the component (B) are diluted with water or an aqueous solution when used. Can be used.
In addition, the additive with low solubility is divided into two components (A) and (B), and when they are used, water or an aqueous solution is added to dilute the components (A) and (B). To do.

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

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

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

Thus, in the present invention, the components of the polishing liquid may be divided into two or more parts and supplied to the surface to be polished. In this case, it is preferable to divide and supply the component containing an oxide and the component containing an organic acid. Alternatively, the polishing liquid may be a concentrated liquid and supplied to the surface to be polished separately from the dilution water.
In the present invention, in the present invention, when applying a method of dividing the polishing liquid components into two or more parts and supplying them to the surface to be polished, the supply amount represents the total supply amount from each pipe. It is.

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

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

[Polishing equipment]
An apparatus capable of performing polishing using the polishing liquid of the present invention is not particularly limited, but Mirra Mesa CMP, Reflexion CMP (Applied Materials), FREX200, FREX300 (Ebara Manufacturing), NPS3301, NPS2301 (Nikon), A-FP -310A, A-FP-210A (Tokyo Seimitsu), 2300 TERES (Ram Research), Momentum (Speedfam IPEC), etc.

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

[Example 1]
A polishing liquid having the composition shown below was prepared and a polishing experiment was conducted.
<Composition (1)>
(A) Abrasive particles: Cerium oxide particles A-1 100 g / L
(B) Benzotriazole derivative: specific example compound B1 1.0 g / L
(C) Acid: Glycolic acid (Wako Pure Chemical Industries, Ltd.) 5 g / L
(E) Water-soluble polymer: polyacrylic acid-polymethacrylic acid copolymer with a weight average molecular weight of 20,000 1.0 g / L
・ Pure water is added and the total volume is 1000mL
・ PH (adjusted with ammonia water and nitric acid) 3.0

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

(Polishing object in polishing rate evaluation)
An 8-inch wafer in which an object to be polished (TEOS insulating layer) was formed on a Si substrate was produced, and a cut wafer cut into 6 cm × 6 cm was used for polishing rate evaluation.

(Polishing object for erosion evaluation)
The silicon oxide film on the Si substrate was patterned by a photolithography process and a reactive ion etching process to form wiring grooves and connection holes having a width of 0.09 to 100 μm and a depth of 600 nm.
Further, a Ta film having a thickness of 20 nm is formed by a sputtering method, a copper film having a thickness of 50 nm is subsequently formed by a sputtering method, and then a copper film having a total thickness of 1000 nm is formed by a plating method (commonly called 854PTN wafer). ) Was cut into 6 × 6 cm.
In this cut wafer, the copper film was separately polished with slurry until the Ta surface appeared, and this wafer was used as a wafer for erosion evaluation. The initial steps of the used wafers were all 10 nm or less.

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

<Erosion evaluation>
A wafer obtained by polishing an object to be polished using the same Cu-CMP slurry for a time corresponding to OP + 30% was used for the step characteristics. The wafer was polished for 45 seconds, and the processed wafer was measured using a stylus-type level difference meter Dektak V320Si (manufactured by Veeco) as the erosion of the 9 μm / 1 μm line / space step. The erosion after Cu-CMP was 15 nm. The obtained results are shown in Table 1.

[Examples 2 to 30 and Comparative Examples 1 to 4]
A polishing experiment was performed under the same polishing conditions as in Example 1 using a polishing liquid prepared by changing the composition in Example 1 to the compositions shown in Tables 1 to 3 below. The results are shown in Tables 1 to 3.

  The (B) benzotriazole derivatives (BTA derivatives) B1 to B24 described in Tables 1 to 3 above refer to the aforementioned exemplary compounds. Moreover, benzotriazole BB1-BB3 used together is the following compounds.

Details of the abbreviated compounds in Tables 1 to 3 are shown below.
TBAN: Tetrabutylammonium nitrate [cationic quaternary ammonium salt compound]
TMAN: Tetramethylammonium nitrate [cationic quaternary ammonium salt compound]
HMC: Hexamethonium chloride [cationic quaternary ammonium salt compound]
DPC: dodecylpyridinium chloride [surfactant]
DBSA: dodecylbenzenesulfonic acid [surfactant]
LTM: Lauryltrimethylammonium nitrate [surfactant]
BTA: 1,2,3-benzotriazole [corrosion inhibitor]

  “-” In Tables 1 to 3 means that a compound corresponding to the item is not added.

  The primary average particle diameters of the abrasive particles described in Tables 1 to 3 are shown in Table 4 below. The primary average particle diameter of the abrasive particles is a value obtained by observing the abrasive particles with an SEM (scanning electron microscope) and measuring the minimum constituent particle diameter constituting one particle.

According to Tables 1 to 3, when the polishing liquids of Examples 1 to 30 were used, the polishing rate of TEOS (insulating layer) was higher than that of Comparative Examples 1 to 4, and the effect of suppressing the occurrence of erosion was achieved. I understand that it is expensive.
On the other hand, it can be seen that the polishing liquids of Comparative Examples 1 to 4 are inferior to the polishing liquids of the examples in terms of both the polishing rate suppressing ability of the TEOS polishing rate and the erosion suppressing effect.

  From the above, it can be seen that the polishing liquid of the present invention is excellent in the TEOS polishing rate, can suppress the occurrence of erosion, and can achieve good flatness.

Claims (12)

A polishing liquid used for chemical mechanical polishing in a planarization process of a semiconductor integrated circuit having an insulating layer,
A polishing liquid comprising (A) cerium oxide particles, (B) a benzotriazole derivative having at least one alkyl group, and (C) an acid. The polishing liquid according to claim 1, wherein the (B) benzotriazole derivative is a compound represented by the following general formula (1).

[In General Formula (1), R < ¹ > -R < ⁵ > represents a hydrogen atom or an alkyl group each independently. However, at least one of R ^{1 to} R ⁵ is an alkyl group. ]   The polishing liquid according to claim 1 or 2, further comprising a quaternary ammonium cation having one or more quaternary nitrogen atoms in the molecule.   The density | concentration of the said (A) cerium oxide particle is the range of 0.05 mass% or more and 15 mass% or less with respect to the total mass of polishing liquid, The any one of Claims 1-3 characterized by the above-mentioned. The polishing liquid described in 1.   The polishing liquid according to any one of claims 1 to 4, wherein the (A) primary average particle diameter of the cerium oxide particles is in the range of 10 nm to 1000 nm.   The (C) acid is at least one selected from the group consisting of oxalic acid, glycolic acid, lactic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, malic acid, tartaric acid, citric acid, and derivatives thereof. The polishing liquid according to claim 1, wherein the polishing liquid is any one of the following compounds.   The polishing liquid according to any one of claims 1 to 6, further comprising a water-soluble polymer.   The polishing liquid according to claim 7, wherein the water-soluble polymer is a polymer or a salt thereof having a carboxyl group-containing monomer as a basic structural unit, or a copolymer containing these.   The polishing liquid according to any one of claims 1 to 8, wherein the pH is 2 or more and 10 or less.   Using a polishing liquid containing (A) cerium oxide particles, (B) a benzotriazole derivative having at least one alkyl group, and (C) an acid, the insulating layer of the semiconductor integrated circuit is mainly chemically and mechanically polished. Polishing method.     11. The polishing method according to claim 10, wherein the concentration of the (A) cerium oxide particles is in the range of 0.05% by mass to 15% by mass with respect to the total mass of the polishing liquid.   12. The polishing method according to claim 10, wherein the semiconductor integrated circuit includes a barrier layer, and the barrier layer formed of Mn, Ti, Ru, or a derivative thereof is polished.