JP2007227669A - Chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical mechanical polishing method capable of improving polishing processing efficiency by continuously polishing a conductor film and a barrier metal film on the same polishing table. <P>SOLUTION: The chemical mechanical polishing method is used to polish a workpiece having a barrier metal film and a conductor film provided on the barrier metal film in a process of manufacturing a semiconductor device. In this method, a first polishing process in which a polishing solution A is used to polish the conductor film, and a second polishing process in which a polishing solution B is used to polish the barrier metal film are continuously executed on the same polishing table having a polishing pad arranged thereon, and the polishing solutions A and B each contain components such as (1) particles having a primary grain size of 20-50 nm and degree of association of 2-5, (2) an organic acid and (3) an oxidizing agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to a chemical mechanical polishing method in a semiconductor device manufacturing process. More particularly, the present invention relates to a chemical mechanical polishing method capable of efficient processing during polishing processing in a semiconductor device manufacturing process.

Copper is a low resistance material in the formation of semiconductor integrated circuits where miniaturization and high density are accelerated, and in recent years, it has attracted much attention as a very useful electrical connection material.
Currently, formation of wiring using copper and an alloy containing copper as a main component is generally performed as follows.
That is, after forming recesses such as grooves and connection holes in the insulating film and forming a barrier metal film, a copper film is formed by plating so as to fill the recesses, followed by chemical mechanical polishing ( (Hereinafter referred to as CMP), the surface of the insulating film other than the recesses is polished until it is completely exposed to flatten the surface, and copper is embedded in the recesses. Electrical connection portions such as embedded copper wiring, via plugs, contact plugs, etc. Is forming.

Hereinafter, a method of forming the buried copper wiring will be described.
A lower wiring layer made of an insulating film having a lower wiring is formed on a silicon substrate, on which a silicon nitride film is formed by chemical vapor deposition and an insulating film is formed in this order by chemical vapor deposition or coating. To do. Next, a recess having a wiring pattern shape and reaching the silicon nitride film is formed in the insulating film.
Subsequently, a barrier metal film is formed by a sputtering method. Thereafter, a copper film (conductor film) is formed on the entire surface by electrolytic plating so that the recesses are embedded.
Thereafter, the copper film is polished by chemical mechanical polishing (CMP) to planarize the substrate surface. Subsequently, CMP is continued until the barrier metal film on the silicon nitride film is completely removed.

A general method of CMP is to rotate a circular polishing platen (platen) to which a polishing pad is attached while dripping and holding the polishing liquid on the surface of the polishing pad, and further to the surface of the substrate (wafer) on the pad surface. The front surface is pressed, the substrate is rotated with a predetermined pressure (polishing pressure) applied from the back surface, and the surface of the substrate is flattened by mechanical friction generated by the relative movement between the polishing platen and the substrate. .
The polishing liquid used for CMP generally includes 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 that the metal surface is oxidized by an oxidizing agent and the oxide film is polished by removing with an abrasive. This technique is described in Non-Patent Document 1, for example. Yes.

However, when CMP is performed using a polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and a phenomenon in which the polished metal surface bends in a dish shape. (Dishing), an insulator between metal wirings is polished more than necessary, and a plurality of wiring metal surfaces may be bent in a dish shape (erosion).
Further, in order to remove the polishing liquid remaining on the surface of the substrate, which is the surface to be polished, after polishing, a process of continuously dropping and supplying ultrapure water after the polishing liquid and washing it off after the polishing is necessary is required. (Referred to as water polishing).

Further, during polishing, solid abrasive grains and polishing debris (polishing product) accumulate on the polishing pad, reducing the retention of the polishing liquid on the surface of the polishing pad, resulting in a decrease in polishing efficiency. . In addition, this deposit also causes scratches on the surface to be polished, which is a major problem in polishing.
Therefore, it is necessary to remove the accumulated solid abrasive grains and polishing debris before performing the next polishing by a process called dressing or conditioning (hereinafter referred to as conditioning).
Thus, after polishing, water polishing and conditioning of the polishing pad are necessary, and it is desirable to omit these steps when considering the efficiency of the polishing process.

On the other hand, in the conventional main method, the CMP is divided into two stages, Cu-CMP for polishing the copper film and barrier CMP for polishing the barrier metal film. Usually, polishing is performed with different polishing liquids and polishing pads. Done.
The main reason is that the optimum polishing pad type and pad conditioning conditions differ depending on the polishing liquid. The term “optimal” as used herein refers to a state in which polishing characteristics such as polishing speed, flattening characteristics, and the presence or absence of scratches are comprehensively adjusted.
Thus, performing Cu-CMP and barrier CMP separately requires extra transport time between each polishing pad, each water polishing time, each conditioning time, etc., and improves the efficiency of the CMP process. It is not preferable.

Therefore, in a chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film such as a copper film provided on the barrier metal film, it is desired to increase the efficiency of the polishing process. is the current situation.
(Journal of Electrochemical Society, 1991, 138, 11, 3460-3464)

This invention is made | formed in view of the said problem, and makes it a subject to achieve the following objectives.
That is, the present invention relates to a chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film provided on the barrier metal film in a semiconductor device manufacturing process, An object of the present invention is to provide a chemical mechanical polishing method in which the barrier metal film and the barrier metal film can be continuously polished on the same polishing surface plate and the efficiency of the polishing process can be improved.

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

<1> A chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film provided on the barrier metal film,
A first polishing step of polishing the conductor film using the polishing liquid A and a second polishing step of polishing the barrier metal film using the polishing liquid B are the same polishing step in which the polishing pad is disposed. A chemical mechanical polishing method, which is carried out continuously on a board, and wherein the polishing liquid A and the polishing liquid B contain the following components (1) to (3).
(1) Particles having a primary particle diameter of 20 to 50 nm and an association degree of 2 to 5 (2) Organic acid (3) Oxidizing agent

  <2> The chemical mechanical polishing method according to <1>, wherein the polishing pads used in the first polishing step and the second polishing step are the same.

  <3> The chemical mechanical polishing method according to <1> or <2>, wherein the polishing liquid A and the polishing liquid B each have a pH of 2 to 9.

  <4> The chemical mechanical polishing method according to any one of <1> to <3>, wherein the particles of (1) are colloidal silica.

<5> The chemical mechanical polishing method according to any one of <1> to <4>, wherein the content of the particles (1) is within the following range.
Polishing liquid A: 0.01-2.0 mass% with respect to the mass of the polishing liquid A
Polishing liquid B: 1.0-10 mass% with respect to the mass of the polishing liquid B

  <6> The oxidizing agent of (3) is hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate <1> characterized by being at least one selected from the group consisting of persulfate, dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt Or the chemical mechanical polishing method according to any one of <5>.

  <7> The chemical mechanical polishing method according to <6>, wherein the oxidizing agent of (3) is hydrogen peroxide.

According to the present invention, there is provided a chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film provided on the barrier metal film in a semiconductor device manufacturing process, the conductor film And the barrier metal film can be continuously polished on the same polishing surface plate, and a chemical mechanical polishing method capable of improving the efficiency of the polishing process can be provided.
According to this polishing method, it is possible to obtain a polished surface having a good surface shape and a reduced residue.

The chemical mechanical polishing method of the present invention is a chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film provided on the barrier metal film,
A first polishing step for polishing the conductor film using the polishing liquid A (hereinafter sometimes simply referred to as “first polishing step”), and the barrier metal film is polished using the polishing liquid B. A second polishing step (hereinafter sometimes simply referred to as a “second polishing step”) is continuously performed on the same polishing platen on which the polishing pad is disposed, and the polishing liquid A And the polishing liquid B contains the following components (1) to (3).
(1) Particles having a primary particle diameter of 20 to 50 nm and an association degree of 2 to 5 (2) Organic acid (3) Oxidizing agent

    Here, in the present invention, the polishing pad arranges “a first polishing step for polishing the conductor film using the polishing liquid A and a second polishing step for polishing the barrier metal film using the polishing liquid B”. "Continuously performed on the same polishing surface plate" means that after polishing the conductor film using the polishing liquid A on the polishing surface plate, the transfer to another polishing surface plate, conditioning, etc. It means that the barrier metal film is polished using the polishing liquid B on the same polishing surface plate as that used for polishing the conductor film without performing the treatment.

First, the following description will be made on the polishing liquid A and the polishing liquid B used in the chemical mechanical polishing method of the present invention.
Hereinafter, the polishing liquid A and the polishing liquid B may be collectively referred to as “polishing liquid”.
The polishing liquid A and the polishing liquid B in the present invention are required to contain the components (1) to (3). By adjusting the amount of each of these components (1) to (3), the polishing liquid A can have a composition suitable for polishing the conductor film, and the polishing liquid B polishes the barrier metal film. It can be set as a suitable composition. As a result, even if the first polishing step and the second polishing step are performed on the same polishing surface plate, the conductor film and the barrier metal film of the object to be polished can be polished.
In addition, the content (addition amount) of various components with respect to the polishing liquid shown below is “the polishing liquid used for polishing (that is, the diluted polishing liquid when diluted with water or an aqueous solution”). It is content (addition amount) with respect to.
The components (1) to (3) will be described in detail.

[(1) Particles having a primary particle size of 20 to 50 nm and an association degree of 2 to 5]
(1) Particles having a primary particle diameter of 20 to 50 nm and an association degree of 2 to 5 (hereinafter referred to as specific particles as appropriate) function as abrasive grains. Particles.
Specific examples of the specific particles include fumed silica, colloidal silica, fumed alumina, and fumed titania. Among them, colloidal silica is preferable in terms of polishing rate and scratches generated during polishing. It is done.

Colloidal silica preferable as the specific particle is, for example, silicon alkoxide such as Si (OC ₂ H ₅ ) ₄ , Si (sec-OC ₄ H ₉ ) ₄ , Si (OCH ₃ ) ₄ , Si (OC ₄ H ₉ ) _4. The compound can be obtained by hydrolysis by a sol-gel method. The colloidal silica thus obtained has a very sharp particle size distribution.

    The primary particle diameter of the specific particles in the present invention is required to be 20 to 50 nm, and more preferably 25 to 40 nm. That is, the primary particle diameter of the specific particles is preferably 20 nm or more for the purpose of suppressing clogging of the polishing pad and preventing scratches on the polishing surface, and 50 nm for the purpose of suppressing dishing. The following is preferred.

Here, the primary particle size of the specific particle in the present invention is a particle size cumulative curve showing the relationship between the particle size of the specific particle and the cumulative frequency obtained by integrating the number of particles having the particle size. This means the particle diameter at the point where the frequency is 50%.
In addition, the particle diameter of this specific particle represents the average particle diameter calculated | required in the particle size distribution obtained from the dynamic light scattering method. For example, LB-500 manufactured by HORIBA, Ltd. is used as a measuring device for obtaining the particle size distribution.

Moreover, the specific particle in this invention requires that the degree of association is 2-5, and 2-3 are more preferable. That is, the degree of association of the specific particles is preferably 2 or more for the purpose of suppressing clogging of the polishing pad and preventing scratches on the polishing surface, and 5 or less for the purpose of suppressing dishing. Is preferred.
Here, the degree of association means a value obtained by dividing the diameter of secondary particles formed by aggregation of primary particles by the diameter of primary particles (secondary particle diameter / primary particle diameter). Here, the degree of association of 1 means only monodispersed primary particles.

As described above, some of the specific particles in the present invention may be associated with each other.
In addition, it is preferable that the secondary particle formed by associating among the specific particles has a particle size in the range of 30 to 80 nm, and more preferably in the range of 40 to 70 nm.
The secondary particle diameter can be measured with an electron microscope or the like.

    Such specific particles can be synthesized, for example, according to the methods described in JP-B-1-59975, JP-A-2-232254, JP-A-2005-60217, JP-A-2005-60219, Commercial products may be used.

(1) The specific particles in the present invention are preferably contained in a proportion of 0.01 to 2.0% by mass with respect to the mass of the polishing liquid A for polishing the conductor film, It is more preferable to contain it in the ratio of the mass%. That is, the content of the specific particles with respect to the polishing liquid A is preferably 0.1% by mass or more in terms of polishing rate, and is preferably 2.0% by mass or less from the dishing point.
On the other hand, the (1) specific particles in the present invention are preferably contained in a proportion of 1.0 to 10% by mass with respect to the mass of the polishing liquid B for polishing the barrier metal film conductor film. It is more preferable to contain it in the ratio of%. That is, the content of the specific particles with respect to the polishing liquid B is preferably 1.0% by mass or more in terms of polishing rate, and is preferably 10% by mass or less in terms of the conductive film (copper) / barrier metal film polishing selection ratio.

[(2) Organic acid]
The polishing liquid in the present invention needs to contain an organic acid. The organic acid here is a compound having a structure different from that of (3) the oxidizing agent used for oxidizing the metal, and does not include an acid that functions as the oxidizing agent.
The organic acid here has an action of promoting oxidation, adjusting pH, and buffering agent.

Specifically, an organic acid selected from the following group is more suitable.
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.

Amino acids are also preferably used as the organic acid in the present invention. The amino acid is preferably water-soluble, and those selected from the following group are more suitable.
That is, for example, glycine, dihydroxyethyl 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-cysteine, L-methionine, L-ethionine, L-lanthionine, L-cystathionine, L- Cystine, L-cysteic acid, L-aspartic acid, L-glutamic acid, S- (carboxyme Chill) -L-cystine, 4-aminobutyric acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L- Examples include amino acids such as histidine, 1-methyl-L-histidine, 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II, and antipine.

Among these organic acids, glycine, dihydroxyethyl glycine, oxalic acid, malonic acid, and succinic acid are preferable for the polishing liquid A for polishing the conductive film, and glycine and dihydroxyethyl glycine are particularly preferable.
Moreover, lactic acid, glycolic acid, and glutaric acid are suitable for the polishing liquid B for polishing the barrier metal film, and glycolic acid is particularly preferred.

In the present invention, (2) the organic acid is preferably added in a proportion of 0.01 to 0.5 mol, and a proportion of 0.05 to 0.3 mol, based on 1 L of the polishing liquid A for polishing the conductor film. More preferably, it is contained. That is, the amount of the organic acid added to the polishing liquid A is preferably 0.01 mol or more in terms of polishing rate, and preferably 0.5 mol or less in terms of planarization characteristics.
On the other hand, (2) the organic acid in the present invention is preferably added at a ratio of 0.05 to 0.7 mol with respect to 1 L of polishing liquid B for polishing the barrier metal film conductor film, More preferably, it is contained at a ratio of 0.5 mol. That is, the amount of the organic acid added to the polishing liquid B is preferably 0.05 mol or more in terms of polishing rate, and is preferably 0.7 mol or less in terms of planarization characteristics.

[(3) Oxidizing agent]
The polishing liquid A and the polishing liquid B in the present invention need to contain an oxidizing agent as a compound capable of oxidizing the metal to be polished.
Specific examples of oxidizing agents include hydrogen peroxide, peroxides, nitrates, iodates, periodates, hypochlorites, chlorites, chlorates, perchlorates, and persulfates. Salts, dichromates, permanganates, ozone water, silver (II) salts, and iron (III) salts are preferable, but hydrogen peroxide is more preferably used in terms of impurity concentration and cost. It is done.

Examples of the iron (III) salt include iron (III) in addition to inorganic iron (III) salts such as iron (III) nitrate, iron (III) chloride, iron (III) sulfate, and iron (III) bromide. ) Organic complex salts are preferably used.
In addition, when an organic complex salt of iron (III) is used, examples of complex-forming compounds constituting the iron (III) complex salt include acetic acid, citric acid, oxalic acid, salicylic acid, diethyldithiocarbamic acid, succinic acid, tartaric acid, and 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 In addition to 3-hydroxysalicylic acid, 3,5-dihydroxysalicylic acid, gallic acid, benzoic acid, maleic acid, and the like, and aminopolycarboxylic acids and salts thereof.

    Specific examples of the aminopolycarboxylic acid and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-diaminopropane-N, N, N ′, N′— Tetraacetic acid, 1,2-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-hydride) Kishibenjiru) 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 the oxidizing agents described above, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and organic complex salts of iron (III) are preferable. In particular, when an organic complex salt of iron (III) is used, preferred complex-forming compounds are 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), ethylenediaminedisuccinic acid (SS), N- ( 2-carboxylate ethyl) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).

    Further, among the oxidizing agents, hydrogen peroxide, persulfate, and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′ , N′-tetraacetic acid, and ethylenediamine disuccinic acid (SS form) are most preferable.

(3) The oxidizing agent in the present invention is preferably added in a proportion of 0.001 to 5 mol, and contained in a proportion of 0.1 to 4 mol, with respect to 1 L of the polishing liquid A for polishing the conductor film. It is more preferable. That is, the amount of the oxidizing agent added to the polishing liquid A is preferably 0.001 mol or more from the viewpoint of polishing rate, and is preferably 5 mol or less from the viewpoint of cost.
On the other hand, (2) the oxidizing agent in the present invention is preferably added in a proportion of 0.001 to 0.5 mol with respect to 1 L of polishing liquid B for polishing the barrier metal film conductor film, More preferably, it is contained in a proportion of 0.2 mol. That is, the amount of the oxidizing agent added to the polishing liquid B is preferably 0.001 mol or more from the viewpoint of the polishing rate of the conductor film, and preferably 0.2 mol or less from the viewpoint of planarization characteristics.

In addition to the components (1) to (3) above, various components as shown below can be added to the polishing liquid in the present invention.
Hereinafter, other components will be described.

[Passive film forming agent]
In the polishing liquid of the present invention, a passive film forming agent can be added as a compound that forms a passive film on the metal surface to be polished and suppresses a chemical reaction on the object to be polished. A heterocyclic compound is used as the passive film forming agent.
Here, the “heterocyclic compound” is a compound having a heterocyclic ring containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom or a hydrogen atom. Moreover, the heterocyclic ring means a cyclic compound having at least one hetero atom. Furthermore, a heteroatom means only those atoms that form part of a heterocyclic ring system, located external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of the ring system are not meant.

    The hetero atom is preferably a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, and a boron atom, and more preferably a nitrogen atom, a sulfur atom, an oxygen atom, and a selenium atom. And particularly preferably a nitrogen atom, a sulfur atom and an oxygen atom, and most preferably a nitrogen atom and a sulfur atom.

First, in the present invention, a heterocyclic ring serving as a mother nucleus of a heterocyclic compound used as a passive film forming agent will be described.
The number of ring members of the heterocyclic ring constituting the heterocyclic compound used in the present invention is not particularly limited, and may be a monocyclic compound or a polycyclic compound having a condensed ring. The number of members in the case of a single ring is preferably 3 to 8, more preferably 5 to 7, and particularly preferably 5 and 6. The number of ring members in the case of having a condensed ring is preferably 2 to 4, more preferably 2 or 3.

Specific examples of these heterocyclic rings include the following. However, it is not limited to these.
That is, pyrrole ring, thiophene ring, furan ring, pyran ring, thiopyran ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, pyrrolidine Ring, pyrazolidine ring, imidazolidine ring, isoxazolidine ring, isothiazolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, chroman ring, thiochroman ring, isochroman ring, isothiochroman ring, indoline ring, isoindoline ring , Pyridine, indolizine, indole, indazole, purine, quinolidine, isoquinoline, quinoline, naphthyridine, phthalazine, quinoxaline, quinazoline, cinnoline, pteridine, Gin ring, perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, anti-lysine ring, thiadiazole ring, oxadiazole ring, triazine ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzothiazole ring Benzothiadiazole ring, benzofuroxan ring, naphthimidazole ring, benzotriazole ring, tetraazaindene ring and the like, more preferably benzotriazole ring, triazole ring and tetrazole ring.

Next, substituents that can be introduced into the heterocyclic ring will be described.
In the present invention, as described below, when a specific part is referred to as a “group”, the part may be one or more (up to the maximum possible number) even if the part itself is not substituted. It means that it may be substituted with a substituent. For example, “alkyl group” means a substituted or unsubstituted alkyl group.

Examples of the substituent that can be introduced into the heterocyclic ring include the following. However, it is not limited to these.
That is, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched, or cyclic alkyl group, even if a polycyclic alkyl group such as a bicycloalkyl group is active) A methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regardless of the position of substitution), an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a heterocyclic oxycarbonyl group, a carbamoyl group ( Examples of the carbamoyl group having a substituent include an N-hydroxycarbamoyl group, an N-acylcarbamoyl group, an N-sulfonylcarbamoyl group, an N-carbamoylcarbamoyl group, a thiocarbamoyl group, and an N-sulfamoylcarbamoyl group), a carbazoyl group. Carboxy group or a salt thereof, oxalyl group, oxamo Group, cyano group, carbonimidoyl group, formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit repeatedly), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy group) Or aryloxy) carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl group, aryl group, or heterocyclic group) amino group, acylamino group, sulfonamido group, ureido group, thioureido group, N-hydroxy Ureido group, imide group, (alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) s A sulfonylurea group, an N-acylureido group, an N-acylsulfamoylamino group, a hydroxyamino group, a nitro group, a heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group) ), Isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group , A sulfo group or a salt thereof, a sulfamoyl group (the sulfamoyl group having a substituent is, for example, an N-acylsulfamoyl group or an N-sulfonylsulfamoyl group) or a salt thereof, a phosphino group, a phosphinyl group, a phosphinyl group Examples include oxy, phosphinylamino, and silyl groups. I can get lost.

The active methine group means a methine group substituted with two electron-withdrawing groups. Examples of the electron-withdrawing group include an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, and an alkyl group. A sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group are meant. Two electron-withdrawing groups may be bonded to each other to form a cyclic structure.
The salt in the above-mentioned substituent means a salt formed by a cation such as alkali metal, alkaline earth metal or heavy metal, or an organic cation such as ammonium ion or phosphonium ion.

    Among these, preferable substituents include, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched, or cyclic alkyl group, and many like a bicycloalkyl group). A cyclic alkyl group or an active methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regarding the position of substitution), an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, Heterocyclic oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, oxalyl group , Oxamoyl group, cyano group, carboximide Ruyl group, formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, Carbamoloxy group, sulfonyloxy group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryloxy) carbonyl Amino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acyl Sulfamoylamino group, hydroxyamino group, nitro group, heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, mercapto group, (Alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, N -Acylsulfamoyl group, N-sulfonylsulfamoyl group or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like.

    More preferably, for example, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an alkyl group (a linear, branched or cyclic alkyl group, and a polycyclic alkyl group such as a bicycloalkyl group). Or an active methine group may be included), an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group (regarding the position of substitution).

Two of the above substituents may be bonded to each other to form a ring structure. Examples of the ring structure formed include an aromatic or non-aromatic hydrocarbon ring or a heterocyclic ring, and these can be further combined to form a polycyclic fused ring.
Specific examples of the ring structure formed by the substituent include, for example, a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, Imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring Quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring It is below.

Specific examples of the heterocyclic compound that can be particularly preferably used in the present invention include, but are not limited to, the following.
That is, 1-H benzotriazole, 1-H tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1,2,3-triazole, 4 -Amino-1,2,3 triazole, 4,5-diamino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino- 1,2,4-triazole.

The heterocyclic compound in this invention may be used independently and may be used together 2 or more types.
Moreover, such a heterocyclic compound can be synthesized according to a conventional method, or a commercially available product may be used.

The heterocyclic compound (passive film forming agent) in the present invention is preferably added at a ratio of 0.01 to 100 mmol with respect to 1 L of polishing liquid A for polishing the conductor film, More preferably, it is contained in a proportion. That is, the amount of the heterocyclic compound added to the polishing liquid A is preferably 0.01 mmol or more in terms of planarization characteristics, and is preferably 100 mmol or less in terms of polishing rate.
On the other hand, the heterocyclic compound (passive film forming agent) in the present invention is preferably added in a ratio of 1 to 100 mmol with respect to 1 L of polishing liquid B for polishing the barrier metal film conductor film, and 5 to 50 mmol. More preferably, it is contained in a proportion of That is, the amount of the heterocyclic compound added to the polishing liquid B is preferably 1 mmol or more in terms of planarization characteristics, and is preferably 100 mmol or less in terms of polishing rate.

[PH adjuster]
The polishing liquid in the present invention can contain an acid agent and an alkali agent for pH adjustment, and further a buffering agent from the viewpoint of pH fluctuation suppression, if necessary.
An inorganic acid is used as the acid agent. Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, and carbonic acid. Among these, nitric acid, phosphoric acid, and carbonic acid are preferable.

    Alkaline agents and buffering agents include organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, non-metallic alkaline agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, Alkali metal hydroxide such as sodium hydroxide, potassium hydroxide, lithium hydroxide, carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt , Leucine salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyamino Use methane salt, lysine salt, etc. It is possible.

    Specific examples of alkaline agents and buffering agents include ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, phosphorus Disodium acid, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5 -Sodium sulfo-2-hydroxybenzoate (sodium 5-sulfosalicylate), potassium 5-sulfo-2-hydroxybenzoate (potassium 5-sulfosalicylate), ammonium hydroxide and the like.

    Particularly preferred alkali agents and buffering agents are ammonia, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

    The addition amount of these pH adjusters (acid agent, alkali agent, buffer agent) may be an amount that maintains the pH within a preferable range, and in any case of polishing liquid A and polishing liquid B. Even so, it is preferably 0.0001 mol to 1.0 mol and more preferably 0.003 mol to 0.5 mol in 1 L of the polishing liquid.

The pH of the polishing liquid adjusted by the above pH adjuster is preferably 2 to 9 in any of the polishing liquid A and the polishing liquid B in the polishing liquid used for polishing. In the case of the polishing liquid A for polishing the conductor film, the pH is preferably 4.0 to 9.0. In the case of the polishing liquid B for polishing the barrier metal film, the pH is 2.0 to 9.0. It is preferably 6.0.
In this range, the polishing liquid in the present invention exhibits particularly excellent effects.

[Surfactant and / or hydrophilic compound]
The polishing liquid in the present invention preferably contains a surfactant and / or a hydrophilic compound. Both the surfactant and the hydrophilic compound (including the hydrophilic polymer) have an action of reducing the contact angle of the surface to be polished, and an action of promoting uniform polishing.

As the surfactant and the hydrophilic compound to be used, those selected from the following group are suitable.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester, and phosphate ester salt. Examples of the carboxylate include soap, N-acyl amino acid salt, polyoxyethylene, or polyoxypropylene alkyl ether. Carboxylate, acylated peptide; as sulfonate, alkylsulfonate, alkylbenzene and alkylnaphthalenesulfonate, naphthalenesulfonate, sulfosuccinate, α-olefinsulfonate, N-acylsulfonate; sulfuric acid As ester salts, sulfated oil, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkylamide sulfates; as phosphate ester salts, alkyl phosphates, polyoxyethylene or Polyoxy B pyrene alkyl allyl ether phosphoric acid salt can be exemplified as preferred.

Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium chloride salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.
Examples of amphoteric surfactants include carboxybetaine type, aminocarboxylate, imidazolinium betaine, lecithin, and alkylamine oxide.

Nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene Polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether; ether ester type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether; ester type, polyethylene glycol Fatty acid ester, glycerol ester, polyglycerol ester, sorbitan ester, propylene glycol ester, Ester; a nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like as preferred.
In addition to these, fluorine-based surfactants and the like can also be used.

    Furthermore, as other surfactants and hydrophilic compounds (including hydrophilic polymers), esters such as glycerin ester, sorbitan ester, methoxyacetic acid, ethoxyacetic acid, 3-ethoxypropionic acid and alanine ethyl ester; polyethylene glycol, Polypropylene glycol, polytetramethylene glycol, polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, alkyl polyethylene glycol, alkyl polyethylene glycol alkyl ether, alkyl polyethylene glycol alkenyl ether, alkenyl polyethylene glycol, alkenyl polyethylene glycol alkyl ether, alkenyl polyethylene glycol alkenyl ether, Polypropylene glycol alkyl Ethers, polypropylene glycol alkenyl ethers, alkyl polypropylene glycols, alkyl polypropylene glycol alkyl ethers, alkyl polypropylene glycol alkenyl ethers, alkenyl polypropylene glycols, alkenyl polypropylene glycol alkyl ethers, and alkenyl polypropylene glycol alkenyl ethers; alginic acid, pectinic acid, carboxymethylcellulose Polysaccharides such as curdlan and pullulan; amino acid salts such as glycine ammonium salt and glycine sodium salt;

  Polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymethacrylic acid, polymethacrylic acid ammonium salt, polymethacrylic acid sodium salt, polyamic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), poly Polycarboxylic acids such as acrylic acid, polyacrylamide, aminopolyacrylamide, ammonium polyacrylate, sodium polyacrylate, polyamic acid, polyamic acid ammonium salt, polyamic acid sodium salt, and polyglyoxylic acid and salts thereof; polyvinyl alcohol Vinyl polymers such as polyvinylpyrrolidone and polyacrolein; methyl taurate ammonium salt, methyl taurate sodium salt, methyl sodium sulfate salt, ethylammonium sulfate Salt, butylammonium sulfate salt, vinylsulfonic acid sodium salt, 1-allylsulfonic acid sodium salt, 2-allylsulfonic acid sodium salt, methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, 3-ethoxypropylsulfonic acid sodium salt Sulfonic acid such as methoxymethylsulfonic acid sodium salt, ethoxymethylsulfonic acid ammonium salt, 3-ethoxypropylsulfonic acid sodium salt and sulfosuccinic acid sodium salt; propionamide, acrylamide, methylurea, nicotinamide, succinic acid Amides such as amides and sulfanilamides, etc.

    Among the above exemplified compounds, cyclohexanol, polyacrylic acid ammonium salt, polyvinyl alcohol, succinic acid amide, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

    However, if the object to be polished to which the polishing liquid containing the above compound is applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable. Or it is preferable to use the ammonium salt. On the other hand, this is not the case when the object to be polished is a glass substrate or the like.

    The weight average molecular weight of these surfactants and / or hydrophilic compounds is preferably 500 to 100,000, particularly 2000 to 50,000.

    The addition amount of the surfactant and / or the hydrophilic compound is preferably 0.001 g to 10 g in 1 L of the polishing liquid A, regardless of whether the polishing liquid A or the polishing liquid B is used. More preferably 5 g, and particularly preferably 0.1 g to 3 g. That is, the addition amount of the surfactant and / or the hydrophilic compound is preferably 0.001 g or more in order to obtain a sufficient addition effect, and is preferably 10 g or less from the viewpoint of preventing a decrease in the CMP rate.

[Dispersion medium]
In the polishing liquid of the present invention, as a dispersion medium, water alone or water as a main component (in the dispersion medium, 50 to 99% by mass), and a water-soluble organic solvent such as alcohol or glycol as a minor component ( 1 to 30% by mass) can be used.
The water is preferably pure water or ion-exchanged water that does not contain macro particles as much as possible.
Examples of the alcohol include methyl alcohol, ethyl alcohol, and isopropyl alcohol, and examples of the glycol include ethylene glycol, tetramethylene glycol, diethylene glycol, propylene glycol, and polyethylene glycol.
The content of the dispersion medium in the polishing liquid is 75 to 95% by mass, preferably 85 to 90% by mass, regardless of whether the polishing liquid A or the polishing liquid B is used. 75 mass% or more is preferable from a viewpoint of the supply property to the to-be-polished body of polishing liquid.

    The polishing liquid A and the polishing liquid B in the present invention are adsorptive and reactive to the polishing surface, the solubility of the metal to be polished, the electrochemical properties of the surface to be polished, the dissociation state of the compound functional group, and the stability as the liquid Depending on the properties, it is preferable to set the compound species, addition amount, pH and dispersion medium in a timely manner.

    In addition, it is preferable that the compounding quantity of the thing with the solubility with respect to the solvent in room temperature among the components added at the time of preparation of the concentrated liquid of polishing liquid is less than twice the solubility with respect to the solvent at room temperature. More preferably, it is within 5 times. If this addition amount is twice or more, it becomes difficult to prevent precipitation when the concentrate is cooled to 5 ° C.

[Polished object having a barrier metal film and a conductor film]
In the present invention, the object to be polished by the polishing liquid, that is, the object to be polished having the barrier metal film and the conductor film preferably has the following wiring.
In the present invention, the object to be polished (the object to be polished) preferably has a wiring made of a copper metal and / or a copper alloy, and particularly preferably has a wiring made of a copper alloy. The material constituting the wiring is preferably a copper alloy containing silver among the copper alloys. 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 copper containing silver in the range of 0.00001 to 0.1% by mass. Exhibits the most excellent effect in alloys.

(Wiring thickness)
In the present invention, the object to be polished with the above-mentioned polishing liquid is preferably an LSI having a wiring with a half pitch of 0.15 μm or less in a DRAM device system. It is more preferable to have a wiring of 10 μm or less, and it is even more preferable to have a wiring of 0.09 μm or less.
On the other hand, in the MPU device system, it is preferable that the LSI has a wiring with a half pitch of 0.12 μm or less, more preferably 0.09 μm or less, and more preferably 0.07 μm or less. Is more preferable.
For these LSIs, the above-described polishing liquid exhibits particularly excellent effects.

(Barrier metal film)
The object to be polished by the polishing liquid described above has a barrier metal film for preventing copper diffusion between a conductor film (wiring made of copper metal and / or copper alloy) and an insulating film described later. Have. The material constituting the barrier metal film is preferably a low-resistance metal material, and may be a laminated structure of a plurality of materials.
The material constituting the barrier metal film is preferably at least one selected from the group consisting of TiN, TiW, Ta, TaN, W, WN, and Ru, and among these, Ta and / or TaN are preferable.

(Insulating film)
It is preferable that the object to be polished by the polishing liquid has an insulating film. As this insulating film, an inorganic insulating film or an organic insulating film can be applied. Specifically, as the insulating film in the present invention, an inorganic insulating film such as a silicon oxide film manufactured by a constant pressure CVD method or a plasma CVD method can be used. In addition, an organic insulating film obtained by a coating method having a hydrolyzed product of tetraalkoxylane as a main component, or an organic insulating film having a low relative dielectric constant having a polyorganosiloxane called an organic SOG as a main component can also be used. .

(Wafer)
The object to be polished (wafer) to be polished with the polishing liquid in the present invention 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.

[Chemical mechanical polishing method]
In the present invention, as the first polishing step, after supplying the polishing liquid A onto the polishing surface plate on which the polishing pad is disposed and polishing the conductive film, without performing other processing steps (conditioning) or the like. As the second polishing step, the barrier metal film is polished by supplying the polishing liquid B onto the same polishing surface plate as used in the first polishing step. Thereby, the barrier metal film and the conductor film can be continuously polished on one polishing surface plate.
In the present invention, in the first polishing step, the end point was that all the conductor film on the barrier metal film was removed and further overpolishing was performed at 30%. When the end point is reached, the supply of the polishing liquid A is stopped, whereby the first polishing step is completed. Thereafter, the supply of the polishing liquid B onto the polishing surface plate is started, whereby the second polishing process is started.
In the second polishing step, the end point was determined by removing the barrier metal film on the insulating film and further polishing the insulating film by 30 nm.
The end points in the first polishing step and the second polishing step can both be detected by an eddy current type end point detector.

As described above, in the polishing method of the present invention, the first polishing step and the second polishing step are continuously performed on the same polishing surface plate. The polishing pad disposed on this polishing surface plate is The same thing may be used by a 1st grinding | polishing process and a 2nd grinding | polishing process, and a different thing may be used. From the viewpoint of increasing the efficiency of the polishing process, it is preferable to use the same polishing pad in the first polishing step and the second polishing step.
Hereinafter, this chemical mechanical polishing method (hereinafter sometimes simply referred to as “polishing method”) will be described.

The polishing liquid in the present invention is (a) a concentrated liquid which is prepared by adding water to dilute to use the liquid, and (b) each component is prepared in the form of an aqueous solution described in the next section. There is an embodiment in which the mixture is mixed and diluted with water as necessary to obtain a use solution, and (c) an embodiment prepared as a use solution from the beginning.
The polishing method of the present invention supplies the polishing liquid used according to such an embodiment onto a polishing pad disposed on a polishing surface plate, and makes the polishing pad contact the surface to be polished of the object to be polished. Thus, polishing is performed by moving the surface to be polished and the polishing pad relative to each other.

As an apparatus used for polishing, a holder for holding an object to be polished (semiconductor substrate or the like) having a surface to be polished and a polishing surface plate (a motor capable of changing the number of rotations) on which a polishing pad is arranged are attached. Can be used.
Here, as a polishing pad, a general nonwoven fabric, a polyurethane foam, a porous fluororesin, etc. can be used, and there is no restriction | limiting in particular.
Further, the polishing conditions are not limited, but the pressure when pressing the surface to be polished of the object to be polished against the polishing pad is preferably 0.68 to 34.5 kPa. In order to satisfy the flatness of the pattern, it is more preferably 3.40 to 20.7 kPa.

Here, 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-plane uniformity of the polishing rate and the flatness of the pattern.

In the first polishing step and the second polishing step, while the polishing is continued, the polishing liquid is continuously supplied to the polishing pad in the apparatus by a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid.
After the first polishing step and the second polishing step in the present invention are completed, the object to be polished after the polishing is thoroughly washed in running water, and then the object to be polished (polishing object) using a spin dryer or the like. The water droplets adhering to the surface) are wiped off and dried.

In the embodiments (a) and (b), the diluting aqueous solution used when obtaining the working liquid of the polishing liquid is the same as the aqueous solutions shown below.
The aqueous solution is water containing at least one of an oxidizing agent, an organic acid, and a surfactant in advance, and a component obtained by adding up the components contained in the aqueous solution and the components of the polishing liquid to be diluted is used for actual polishing. It becomes a component of the working liquid of the polishing liquid when used.
As described above, when diluting with an aqueous solution when using the solution, it is possible to mix components that are difficult to dissolve in the form of an aqueous solution, so that a more concentrated polishing liquid can be prepared. .

As a method of diluting by adding water or an aqueous solution to the concentrated polishing liquid as in the aspect (a), a pipe for supplying the concentrated polishing liquid and a pipe for supplying the water or the aqueous solution in the polishing apparatus. Are preferably mixed and mixed in the middle. The polishing liquid mixed and diluted in this way is supplied to the polishing pad to perform polishing. For mixing the liquid, a method in which the liquids collide with each other through a narrow passage under pressure, a method in which a filling such as a glass tube is filled in the pipe, a flow of the liquid is separated, and the liquid flow is repeatedly performed, Conventional methods such as a method of providing blades that rotate with power in the pipe can be employed.

    As a method of polishing while diluting the concentrated polishing liquid with water or an aqueous solution, etc., a pipe for supplying the polishing liquid and a pipe for supplying water or an aqueous solution are independently provided in the polishing apparatus, and a predetermined amount is provided from each. The liquid is supplied to the polishing pad, and the polishing is performed while mixing by the relative movement of the polishing pad and the surface to be polished. It is also possible to apply a method in which a predetermined amount of the concentrated polishing liquid and water or an aqueous solution are mixed in one container and then the mixed polishing liquid is supplied to the polishing pad to perform polishing.

As in the embodiment (b), the component to be contained in the polishing liquid is divided into at least two components, and when these are used, if necessary, diluted with water or an aqueous solution to dilute the polishing liquid. It is also suitable in the present invention to prepare a working solution.
In this case, specifically, for example, (3) an oxidizing agent is one constituent component (A), (2) an organic acid, a surfactant, and water are one constituent component (B), and they are used. When doing, the method of diluting a structural component (A) and a structural component (B) with water or aqueous solution as needed is used.
In addition, the low-solubility additive is divided into two components (A) and (B), (3) the oxidizing agent and the surfactant are one component (A), and (2) the organic acid, the interface It is also possible to use the activator and water as one component (B) and dilute the component (A) and component (B) by adding water or an aqueous solution when using them.

In the case of the method of polishing while preparing the working liquid of the polishing liquid as in the above example, three pipes for supplying the component (A), the component (B) and water or an aqueous solution, respectively, into the polishing apparatus In order to dilute and mix, three pipes are connected to one pipe supplied to the polishing pad and mixed in the pipe.
It is also possible to combine two pipes and then connect another one pipe. This is suitable, for example, for 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 a pipe for water or an aqueous solution is further combined. It is.
The use liquid of the polishing liquid thus mixed is continuously supplied to the polishing pad on the polishing surface plate and brought into contact with the surface to be polished to move the surface to be polished and the polishing pad relative to each other so that polishing can be performed. Done.

    Further, as another mixing method in the polishing apparatus, as described above, each of the three pipes is directly guided to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished. There is a method of mixing the constituent component (A), the constituent component (B), and water or an aqueous solution, and supplying the diluted polishing liquid to the polishing pad therefrom.

In the above-described embodiment (b), when (3) one component containing an oxidizing agent is made 40 ° C. or lower and the other components are heated in the range of room temperature to 100 ° C., these are mixed. Alternatively, it is also possible to use a method of mixing these and further diluting by adding water or an aqueous solution to a liquid temperature of 40 ° C. or lower. This method is a preferable method for increasing the solubility of the raw material having a low solubility constituting the polishing liquid because the solubility of the solute increases when the liquid temperature is high.
Further, (3) since the oxidizing agent may be decomposed when the temperature of one constituent component containing the oxidizing agent is increased to 40 ° C. or higher, as described above, (3) It is desirable that the temperature be 40 ° C. or lower when one constituent component containing an oxidizing agent is mixed, or when these components are mixed and further diluted.

    As mentioned above, other components that do not contain an oxidant are heated and dissolved in the range from room temperature to 100 ° C., because the dissolved components are precipitated in the solution when the temperature drops, The polishing apparatus is preferably provided with a means for dissolving components that can be deposited by heating. For this, it is possible to employ a means for feeding a component liquid that has been heated and dissolved, or a means for stirring a liquid containing precipitates, feeding the liquid, and heating and dissolving the piping.

    As described above, in the present invention, the components of the polishing liquid may be divided into two or more parts and supplied to the polishing surface. In this case, it is preferable to divide and supply (3) a component containing an oxidizing agent and (2) a component containing an organic acid. Alternatively, the polishing liquid may be a concentrated liquid, and diluted water may be separately supplied to the polishing surface.

(Polishing pad)
The polishing pad used in the present invention may be a non-foamed structure pad or a foamed structure pad. The former uses a hard synthetic resin bulk material like a plastic plate for a pad. Further, the latter further includes three types of a closed foam (dry foam system), a continuous foam (wet foam system), and a two-layer composite (laminated system), and a two-layer composite (laminated system) is particularly preferable. Foaming may be uniform or non-uniform.

    Further, it may contain abrasive grains (for example, ceria, silica, alumina, resin, etc.) used for polishing. 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. The material is preferably non-woven fabric, artificial leather, polyamide, polyurethane, polyester, polycarbonate or the like. In addition, the surface contacting the polishing surface may be subjected to processing such as lattice grooves / holes / concentric grooves / helical grooves.

    Although the apparatus which can implement the polishing method of the present invention is not particularly limited, Mirror 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 (novelas), etc. can be mentioned.

    Hereinafter, the present invention will be described by way of examples. The present invention is not limited to these examples.

<(1) Specific particles and other abrasive grains>
Based on a known method, (1) specific particles and other abrasive grains were prepared and prepared as follows.
Colloidal silica (S-1): Colloidal silica produced based on the method described in JP-A-2005-60217 (primary particle diameter 15 nm, secondary particle diameter 40 nm, association degree 2.7)
Colloidal silica (S-2): Colloidal silica prepared based on the method described in JP-A-2005-60217 (primary particle diameter 20 nm, secondary particle diameter 50 nm, association degree 2.5)
Colloidal silica (S-3): Colloidal silica prepared based on the method described in JP-A-2005-60217 (primary particle diameter 35 nm, secondary particle diameter 70 nm, association degree 2.0)
Colloidal silica (S-4): Colloidal silica prepared based on the method described in JP-A-2005-60217 (primary particle diameter 20 nm, secondary particle diameter 25 nm, association degree 1.3)
Colloidal silica (S-5): Colloidal silica produced based on the method described in JP-A-2005-60219 (primary particle diameter 20 nm, secondary particle diameter 140 nm, association degree 7.0)
Colloidal silica (S-6): Colloidal silica produced based on the method described in JP-A-2005-60217 (primary particle diameter 20 nm, secondary particle diameter 60 nm, association degree 3.0)

<Preparation of polishing liquid A>
After mixing the following composition, the mixture was stirred and uniformly dispersed with a high-speed homogenizer to obtain polishing liquids A-1 to A-6.
(1) Specific particles or other abrasive grains 2.0 g / L
・ (3) Oxidizing agent: hydrogen peroxide (amount that gives the concentration shown in Table 1)
(2) Organic acid: compounds listed in Table 1 (amounts that result in the concentrations listed in Table 1)
-Heterocyclic compound: benzotriazole (amount to be the concentration shown in Table 1)
-Pure water The total amount of 1000 ml The pH of the polishing liquids A-1 to A-6 was adjusted using ammonia water and nitric acid so as to have the values shown in Table 1.

<Preparation of polishing liquid B>
After mixing the following composition, the mixture was stirred and uniformly dispersed with a high-speed homogenizer to obtain polishing liquids B-1 to B-5.
・ (1) Specific particles or other abrasive grains 90g / L
・ (3) Oxidizing agent: hydrogen peroxide (amount that gives the concentration shown in Table 1)
(2) Organic acid: compounds listed in Table 1 (amounts that result in the concentrations listed in Table 1)
-Heterocyclic compound: benzotriazole (amount to be the concentration shown in Table 1)
-Pure water Amount of the total amount of 1000 ml The pH of the polishing liquids B-1 to B-5 was adjusted using ammonia water and nitric acid so as to have the values shown in Table 1.

    The polishing liquids A-1 to A-6 and the polishing liquids B-1 to B-5 were combined as shown in Table 2 below to give Examples 1 to 4 and Comparative Examples 1 to 6, and various types shown below. A polishing test was conducted.

<Measurement of polishing time>
As a polishing apparatus, an apparatus “FREX-300” manufactured by Ebara Corporation is used, and a slurry (polishing liquid A and polishing liquid B) is supplied under the following conditions, and a conductive film and a barrier provided on the following wafer to be polished: The metal film was polished.
The polishing process is as shown below.
That is, the polishing liquid A is supplied onto the polishing pad placed on the polishing surface plate to polish all the conductor film (first polishing step), and then the same polishing is continuously placed on the same polishing surface plate. Polishing was performed through a process of supplying the polishing liquid B onto the pad to polish the barrier metal film (second polishing process) and then cleaning the surface to be polished with water polish.
The end point of the first polishing step using the polishing liquid A was a point where overpolishing corresponding to 30% was performed using an eddy current type end point detector attached to the polishing apparatus. Here, the supply of the polishing liquid A was stopped, the supply of the polishing liquid B was started, and the barrier metal film was continuously polished. Here, the end point of the second polishing step was a point where the barrier metal film was removed and the silicon oxide film was further polished by 30 nm.
As described above, the time required for polishing (polishing time required for the first polishing step + polishing time required for the second polishing step) was determined. The results are shown in Table 2 below.

(Polishing target) Polishing target wafer: Pattern wafer with 12 inch (φ300 mm) copper film 754CMP003, manufactured by atdf (on the silicon substrate, a 500 nm oxide film was deposited and a pattern was formed on the 25 nm Ta film (barrier Metal film) and 4000 nm Cu film (conductor film) in this order)

(Polishing conditions)
・ Processing linear velocity: 2.0m / s
・ Polishing pressure: 140 hPa
・ Polishing pad: Product number IC-1400 K-grv + A21 manufactured by Rodel Nitta Co., Ltd.
・ Slurry supply rate: 300 ml / min

<Observation of polishing residue of conductor film and barrier metal film>
Conductor film and barrier metal film on the exposed polished surface of the patterned wafer after copper or barrier film remains on the insulating film or after polishing is finished by the method described in the above measurement of polishing time The presence or absence of polishing residue was visually observed using a differential interference optical microscope (MX-80, manufactured by Olympus Corporation). The measurement results were evaluated in the following two stages. The results are shown in Table 2 below.
○: No polishing residue of conductor film and barrier metal film ×: Polishing residue of conductor film and barrier metal film

<Measurement of scratches>
The scratches are evaluated by polishing a wafer to be polished (blanket wafer) shown below by the method described in the above-mentioned measurement of the polishing time, and the exposed polished surface after the polishing is finished with KLA Tencor. This was done by measuring a scratch of 0.2 μm or more present on the surface to be polished, using a manufactured foreign matter inspection apparatus SP1-TBI.
Wafer to be polished: Blanket wafer with 12 inch (φ300 mm) copper film (a 500 nm oxide film is deposited on a silicon substrate, and then a 25 nm Ta film (barrier metal film) and a 4000 nm Cu film (conductor film)) And in this order)

The number of scratches of 0.2 μm or more present on the surface to be polished was evaluated in the following three stages. The results are shown in Table 2 below.
○: Less than 10 △: 10 or more and less than 50 (allowable range)
×: 50 or more

<Dishing and erosion measurement>
The dishing and erosion on the exposed polished surface of the pattern wafer after the polishing was finished by the method described in the above measurement of the polishing time were measured using a contact level difference measuring device Dektak V320Si (Veeco).

From the results of Table 2, even when the conductor film and the barrier metal film were continuously polished with one polishing surface plate and one polishing pad as in the polishing tests of Examples 1 to 4, the polishing was performed. It can be seen that there is no polishing residue on the surface and there is no problem of scratches. Moreover, in Examples 1-4, it turns out that the result more than equivalent to a comparative example is obtained about total polishing time, dishing, and erosion.
On the other hand, Comparative Examples 1 and 2 using the polishing liquid A or the polishing liquid B in which the primary particle diameter of the colloidal silica is too small are equivalent to the examples in the dishing and erosion, and no polishing residue occurs on the polished surface. It can be seen that the total polishing time tends to be longer than in the example, and many scratches are generated on the polished surface.
Further, Comparative Example 3 and Comparative Example 5 using the polishing liquid A or the polishing liquid B in which the degree of association of the colloidal silica is too low are equivalent to the examples in terms of the total polishing time, dishing and erosion, and scratches on the polished surface Although there is no problem, it can be seen that there is a polishing residue on the polished surface. This is because clogging of the colloidal silica into the polishing pad is likely to occur.
Further, Comparative Example 4 and Comparative Example 6 using the polishing liquid A or the polishing liquid B in which the degree of association of the colloidal silica is too high, the total polishing time is short, the polishing speed is excellent, and no polishing residue is generated on the polishing surface. It can also be seen that the erosion is large and that many scratches are generated on the polished surface.

Claims (7)

A chemical mechanical polishing method for polishing an object to be polished having a barrier metal film and a conductor film provided on the barrier metal film,
A first polishing step of polishing the conductor film using the polishing liquid A and a second polishing step of polishing the barrier metal film using the polishing liquid B are the same polishing step in which the polishing pad is disposed. A chemical mechanical polishing method, which is carried out continuously on a board, and wherein the polishing liquid A and the polishing liquid B contain the following components (1) to (3).
(1) Particles having a primary particle diameter of 20 to 50 nm and an association degree of 2 to 5 (2) Organic acid (3) Oxidizing agent     The chemical mechanical polishing method according to claim 1, wherein the polishing pads used in the first polishing step and the second polishing step are the same.     The chemical mechanical polishing method according to claim 1 or 2, wherein the polishing liquid A and the polishing liquid B each have a pH of 2 to 9.     The chemical mechanical polishing method according to any one of claims 1 to 3, wherein the particles of (1) are colloidal silica. 5. The chemical mechanical polishing method according to claim 1, wherein the content of the particles of (1) is within the following range.
Polishing liquid A: 0.01-2.0 mass% with respect to the mass of the polishing liquid A
Polishing liquid B: 1.0-10 mass% with respect to the mass of the polishing liquid B     The oxidizing agent (3) is hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate The at least one selected from the group consisting of a salt, a dichromate, a permanganate, ozone water, a silver (II) salt, and an iron (III) salt. 6. The chemical mechanical polishing method according to any one of 5 above.     The chemical mechanical polishing method according to claim 6, wherein the oxidizing agent of (3) is hydrogen peroxide.