JP2010129941A - Metal polishing liquid, and chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metal polishing liquid achieving high precise polishing at high speed, by which dishing is lessened even in high-purity materials and erosion is suppressed on fine wirings to manufacture an LSI chip with improved flatness, and to provide a chemical mechanical polishing method using the liquid, which ensures high productivity even in manufacturing large-scale substrates. <P>SOLUTION: The metal polishing liquid used for chemical mechanical flattening of semiconductor devices contains (A) a nonionic surfactant having a poly(oxyalkylene) group in its molecule and having an HLB value within a range of 12-18, (B) one or more nonionic surfactants selected from the group consisting of sucrose fatty acid esters and alkyl(poly)glucosides, (C) an oxidizing agent, (D) an organic acid, and (E) a heterocyclic compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to the manufacture of semiconductor devices, and more particularly to a metal polishing liquid in a wiring process of semiconductor devices and a chemical mechanical polishing method using the same.

In the development of a semiconductor device typified by a semiconductor integrated circuit (hereinafter referred to as LSI), high density and high integration by miniaturization and lamination of wiring are required for high integration and high speed. As a technique for this purpose, chemical mechanical polishing (Chemical Mechanical Polishing) that polishes an insulating thin film (SiO ₂ or the like) or a metal thin film used for wiring and smoothes the substrate or removes excess metal thin film during wiring formation. Various methods such as Polishing (hereinafter referred to as CMP) have been used.
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.
The metal polishing liquid used for CMP generally contains abrasive grains (for example, alumina, silica) and an oxidizing agent (for example, hydrogen peroxide, persulfuric acid). The metal surface is oxidized by the oxidizing agent, and the oxidation is performed. It is considered that the film is polished by removing the film with abrasive grains.

However, when CMP is performed using a metal polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), and the polished metal surface is flat In addition, a phenomenon in which only the center is polished deeper to form a dish-like depression (dishing), an insulator between metal wirings is polished more than necessary, and a plurality of wiring metal surface surfaces form dish-shaped recesses. A phenomenon (erosion) may occur.
In order to solve the problems in such conventional solid abrasive grains, a metal polishing liquid which does not contain abrasive grains and is composed of hydrogen peroxide / malic acid / benzotriazole / ammonium polyacrylate and water is disclosed. (For example, refer to Patent Document 1). According to this method, although the metal film on the convex portion of the semiconductor substrate is selectively CMPed and the metal film is left in the concave portion to obtain a desired conductor pattern, it is mechanically softer than the case containing solid abrasive grains. Since CMP proceeds due to friction with the polishing pad, it is difficult to obtain a sufficient polishing rate.

  Recently, in order to improve productivity, the wafer diameter at the time of LSI manufacture has been increased, and nowadays, a diameter of 200 mm or more is widely used, and manufacturing with a size of 300 mm or more has started. With such an increase in size, the temperature change during polishing increases, but it becomes more difficult to control the flatness of the wafer due to the influence of the polishing temperature. For this reason, the difference in the polishing rate between the wafer central portion and the peripheral portion is increased, and the demand for improvement in the in-plane uniformity is increasing.

  On the other hand, an LSI using copper having low wiring resistance has been developed as a metal for wiring in place of conventional general-purpose tungsten or aluminum as a metal for wiring. Along with the miniaturization of wiring aiming at higher density, it is necessary to improve the conductivity and electron migration resistance of the copper wiring, and accordingly, use a copper alloy in which a small amount of a third component such as silver is added to high purity copper. This is beginning to be considered. At the same time, there is a need for high-speed metal polishing means that can exhibit high productivity without contaminating these high-definition and high-purity materials.

As a chemical polishing method having no mechanical polishing means for copper and a copper alloy, a chemical polishing method using only a dissolving action is also known (see, for example, Patent Document 2). However, as compared with CMP in which the metal film of the convex portion is selectively chemically and mechanically polished, problems such as dishing are likely to occur, and ensuring flatness is a problem.
In addition, for the purpose of flattening the level difference of the polished surface, means for adding an anionic surfactant or a cationic surfactant to the polishing liquid have been proposed, but anionic surfactants generally lower the polishing rate. There has been a concern, and there has been a demand for a method of effectively suppressing the occurrence of dishing while maintaining a high polishing rate, such as a problem with the stability of cationic surfactants.

In addition, as a method of adding a nonionic surfactant, a partially esterified product of a polyhydric alcohol compound, an alkylene oxide adduct thereof, a monosaccharide or a fatty acid ester thereof, or the like is used in combination with an anionic surfactant. (Refer to Patent Documents 5 to 7), however, the performance is still inadequate. In response to the recent increase in the size of wafer substrates, a new method is required to polish high-purity materials with high definition. A method was awaited. There is also a problem that erosion occurs in fine wiring.
JP 2001-127019 A JP 49-122432 A JP 2001-303050 A JP 2001-298004 A Japanese Patent No. 4021080 JP 2004-58661 A JP 2008-41882 A

The problem to be solved by the present invention is to fabricate an LSI that has a rapid polishing rate and that has high precision, high purity material, little dishing, erosion of fine wiring is suppressed, and flatness is improved. An object of the present invention is to provide a metal-polishing liquid that makes it possible to achieve this.
It is another object of the present invention to provide a chemical mechanical polishing method that uses the metal polishing liquid to obtain high productivity even with a large substrate.

  As a result of intensive studies on the problems associated with the above-described metal polishing liquid, the present inventors have found that the problem can be solved by using the following metal polishing liquid, and have achieved the object. That is, the means for solving the problems of the present invention are as follows.

<1> (A) Nonionic surfactant having a poly (oxyalkylene) group in the molecule and an HLB value in the range of 12 to 18, (B) sucrose fatty acid ester and alkyl (poly) glucoside For chemical mechanical planarization of a semiconductor device containing at least one nonionic surfactant selected from the group consisting of: (C) an oxidizing agent, (D) an organic acid, and (E) a heterocyclic compound Polishing liquid for metal.

<2> The amount of the nonionic surfactant having a poly (oxyalkylene) group in the molecule (A) and having an HLB value in the range of 12 to 18 is defined as (a). When the amount of one or more nonionic surfactants selected from sugar fatty acid esters or alkyl (poly) glucosides is (b), the ratio (a) / (b) is 0.3 to 10 The metal polishing slurry according to <1>, which is a range.

<3> The metal polishing slurry according to claim 1 or 2, wherein the sucrose fatty acid ester contains a sucrose fatty acid monoester.
<4> The metal polishing slurry according to any one of <1> to <3>, wherein the alkyl (poly) glucoside is selected from decyl glucoside and lauryl glucoside.

<5> The metal polishing liquid according to any one of <1> to <4>, wherein the metal polishing liquid is mainly used for polishing copper wiring in chemical mechanical planarization of a semiconductor device.
<6> The metal polishing liquid according to any one of <1> to <5> is supplied to a polishing pad on a polishing surface plate, and the polishing surface plate is rotated to rotate the polishing pad. A chemical mechanical polishing method in which polishing is carried out by relative movement while being in contact with a surface to be polished.

  In the present invention, (A) a specific nonionic surfactant having a poly (oxyalkylene) group in the molecule and (B) a nonionic surfactant such as a sucrose fatty acid ester are used in combination. As a result, a substrate having a high polishing rate, a low dishing, and improved flatness was obtained. The reason why this effect is obtained is not clear, but (A) a specific nonionic surfactant having a poly (oxyalkylene) group, and (B) a nonionic surfactant such as a sucrose fatty acid ester Is selectively adsorbed on a conductive metal such as copper and hardly adsorbed on a barrier metal due to its structure. Further, although it becomes a micelle state at high temperature and insolubilizes and does not form an adsorbed film, it is considered that the adsorbed film is formed by solubilizing at low temperature, and this film has less dishing and a high polishing rate.

According to the present invention, in chemical mechanical polishing in the manufacture of semiconductor devices, it has a rapid polishing rate, and even with high-definition, high-purity material, less dishing, erosion in fine wiring is suppressed, and flatness It is possible to provide a metal-polishing liquid that enables the production of an LSI with improved resistance.
Further, it is possible to provide a chemical mechanical polishing method using the metal polishing liquid, which can obtain high productivity even with a large-sized substrate.

Hereinafter, specific embodiments of the present invention will be described.
[Metal polishing liquid]
The metal polishing liquid of the present invention is a metal polishing liquid used for chemical mechanical polishing of a conductor film mainly composed of copper or a copper alloy in the manufacturing process of a semiconductor device. A nonionic surfactant having an oxyalkylene) group and an HLB value in the range of 12 to 18 (hereinafter sometimes referred to as surfactant A), (B) sucrose fatty acid ester and alkyl (poly ) One or more nonionic surfactants selected from the group consisting of glucosides (hereinafter sometimes referred to as surfactant B), (C) oxidizing agents, (D) organic acids, and (E) complex It contains a ring compound.
Hereinafter, each component contained in the metal-polishing liquid of the present invention will be sequentially described.

<(A) Nonionic surfactant having a poly (oxyalkylene) group in the molecule and an HLB value in the range of 12 to 18>
The surfactant A used in the present invention has an oxyalkylene group in the molecule in the range of 4 to 50, preferably in the range of 8 to 30, and the oxyalkylene group includes an oxyethylene group, Examples thereof include an oxypropylene group, an oxybutylene group, an oxyethylene group, and an oxypropylene group, and these can be included alone or in combination.
When the oxyalkylene group is within the above range, dishing is good, and for the same reason, the oxyalkylene group is preferably an oxyethylene group.

  Surfactant A preferably used in the present invention includes polyalkyleneoxyalkyl ether, polyalkyleneoxyalkoxyalkyl ether, polyalkyleneoxyalkylphenyl ether and the like. The alkyl group is an alkyl group that may have a branched structure having 8 to 30 carbon atoms, preferably 10 to 20 carbon atoms, and the alkoxyalkyl group is substituted with an alkoxy group having 1 to 20 carbon atoms, preferably 6 to 12 carbon atoms. The alkyl group is preferably a phenyl group substituted with an alkyl group which may contain a branched structure having 1 to 20, preferably 6 to 12 carbon atoms.

  The HLB of the surfactant A needs to be in the range of 12-18, and is preferably in the range of 14-17. By using the surfactant A having an HLB within the above range, dishing is improved.

Although the preferable specific example of surfactant A and HLB of the said surfactant are mentioned, this invention is not restrict | limited to these. In addition, () in the following compound name indicates the number of oxyalkylene units.
Polyoxyethylene (5) decyl ether (HLB 12.1) (FINESURF D-1305 made by Aoki Yushi)
Polyoxyethylene (8) octylphenyl ether (HLB 12.5) (Triton X-114 manufactured by Dow Chemical Company)
Polyoxyethylene (8) tridecyl ether (HLB 12.7) (FINESURF TD-80 made by Aoki Yushi)
Polyoxyethylene (50) stearyl ether (HLB 17.8) (Blanoon SR-750, manufactured by Aoki Yushi)
Polyoxyethylene (50) Lauryl ether (HLB 12.6) (Peretex 2465 made by Miyoshi Oil & Fats)
Polyoxyethylene (9) secondary alcohol ether (HLB 13.3) (FINESURF 290 made by Aoki Yushi)
The “secondary alcohol ether” of the “polyoxyethylene (9) secondary alcohol ether” is an ether produced from a secondary alcohol in which various carbon numbers are mixed.

<(B) One or more nonionic surfactants selected from the group consisting of sucrose fatty acid esters and alkyl (poly) glucosides>
The sucrose fatty acid ester of the surfactant B used in the present invention is a fatty acid ester having a fatty acid group having 8 to 18 carbon atoms, and 1 to 8 fatty acid groups may be substituted with sucrose. .
These specific compounds are sucrose fatty acid monoesters, sucrose fatty acid diesters, sucrose fatty acid triesters, sucrose fatty acid polyesters, or mixtures thereof.

Preferably, it is a sucrose fatty acid monoester in which one fatty acid group having 8 to 18 carbon atoms is substituted.
The fatty acid may be a branched fatty acid or an unsaturated fatty acid, but is preferably a saturated linear fatty acid. As examples, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid and the like are preferable.

Specific examples of the sucrose fatty acid ester include sucrose stearic acid monoester, sucrose palmitic acid monoester, sucrose myristic acid monoester, sucrose lauric acid monoester, and the like. These may be diesters, triesters, polyesters, or may be mixtures containing monoesters.
A sucrose fatty acid monoester mixed with sucrose fatty acid diester, sucrose fatty acid triester, and sucrose fatty acid polyester is also a preferred embodiment.

  As a suitable commercial item, DK ester SS (monoester 100%, HLB = 19), DK ester F-110 (monoester / di-tri-polyester = mass ratio 50/50, HLB = 11, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. ), DK ester F-90 (monoester / di-tri polyester = mass ratio 45/55, HLB = 9.5), DK ester F-70 (monoester / di-tri polyester = mass ratio 40/60) , HLB = 8), DK ester F-50 (monoester / di-tri-polyester = mass ratio 30/70, HLB = 6), and the like. In the above, the monoester means a mixture of stearic acid monoester / palmitic acid monoester = mass ratio 70/30.

The alkyl (poly) glucoside is a (poly) glucoside having an alkyl group having 8 to 18 carbon atoms, preferably an alkyl group having 9 to 14 carbon atoms, and a plurality of alkyl groups may be substituted. .
In the present invention, the expression “alkyl (poly) glucoside” refers to both and / or “alkyl glucoside (compound having a sugar condensation degree of 1)” and “alkyl polyglucoside”. Represents that the condensation degree of sugar is larger than 1. In the alkylpolyglucoside in the present invention, the condensation degree of sugar is preferably 1.1 to 5.0, and more preferably 1.1 to 2.0.
Specific examples include decyl glucoside (HLB = 10), lauryl glycoside (HLB = 11), alkyl polyglycoside in which an alkyl group having 12 carbon atoms and an alkyl group having 14 carbon atoms are mixed (condensation degree of sugar = 1. 2, HLB = 11.5).

  Among these, a preferable compound as the surfactant B of the present invention is sucrose fatty acid ester containing at least one sucrose fatty acid monoester, or decylglucoside.

The addition amount of the above-described surfactant A and surfactant B used in the present invention may be any of the above-described embodiments, and as a total amount, the metal polishing liquid (i.e. water) Or when diluting with aqueous solution, the range of 1-1000 ppm is each independently preferable in the metal polishing liquid after dilution), More preferably, it is the range of 10-800 ppm, More preferably, it is the range of 20-600 ppm.
As the mass ratio of the surfactant A and the surfactant B, the content of the surfactant A is (a), and the content of the surfactant B is (b). / (B) is preferably in the range of 0.3 to 10, more preferably in the range of 0.5 to 5.0, and still more preferably in the range of 0.7 to 1.0. Within this range, the polishing rate and dishing are good.

  As long as the effects of the present invention are not impaired, a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant having other structures may be added and used.

  Specific examples of the nonionic surfactant other than the surfactant A and the surfactant B that can be used in the present invention include sorbitan fatty acid esters (for example, sorbitan monolaurate, Sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate), glycerin fatty acid ester (eg glycerol monostearate, glycerol monooleate), polyglycerin ester Sorbitan ester, propylene glycol ester, fatty acid alkanolamide (for example, coconut fatty acid diethanolamide) and the like. Moreover, a fluorine-type surfactant, an acetylene containing nonionic surfactant (For example, diisobutyl dimethyl butynediol polyoxyethylene glycol ether) etc. are mentioned.

  As the anionic surfactant, carboxylic acid, sulfonic acid, phosphate ester, sulfate ester and mixed surfactants thereof are preferable, and carboxylic acid and sulfate surfactants are particularly preferable.

As the carboxylic acid surfactant, those having a —CONR ⁴ — group (R ⁴ represents H or a methyl group) are preferable. Examples include N-acyl amino acid salts (for example, coconut oil fatty acid sarcosine triethanolamine, lauroyl sarcosine potassium, oleyl sarcosine, sodium lauroylmethylalanine).

The sulfonic acid surfactant is at least selected from the group consisting of a phenyl group, a —CONR ⁵ — group (R ⁵ represents H or an alkyl group having 1 to 3 carbon atoms), and a —COO— group. Those having one group are preferred. For example, dodecylbenzenesulfonic acid, coconut oil fatty acid methyl taurine sodium, di (or mono) alkylsulfosuccinic acid (for example, sodium dioctylsulfosuccinate, disodium sulfosuccinate of alkyl ether-polyoxyethylene 4-adduct having 12 to 14 carbon atoms) ), Etc.

  As the phosphate ester surfactant, those having a polyoxyethylene group or a phenyl group are preferable. For example, polyoxyethylene alkylphenyl ether phosphoric acid, polyoxyethylene alkyl ether phosphoric acid (for example, di- (polyoxyethylene 10 adduct) sodium lauryl ether phosphate, di (polyoxyethylene diadduct-carbon number 12) ˜15 alkyl ether phosphoric acid), and the like.

As the sulfate ester surfactant, those having a polyoxyethylene group or a —CONR ⁶ — group (R ⁶ represents H or a methyl group) are preferable. For example, polyoxyethylene coconut oil fatty acid sodium monoethanolamide sulfate, polyoxyethylene alkyl ether sulfate (for example, sodium polyoxyethylene lauryl ether sulfate, polyoxyethylene lauryl ether sulfate triethanolamine) and the like can be mentioned.

  These anionic surfactants may form alkali metal salts (for example, sodium salts, potassium salts), ammonium salts, and amine salts (for example, triethanolamine salts). An amine salt is preferable, and an ammonium salt and a potassium salt are particularly preferable.

  Examples of cationic surfactants include alkylamine salts (for example, coconut amine acetate, stearylamine acetate), quaternary ammonium salts (for example, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, cetyltrimethylammonium chloride, distearyl). Dimethylammonium chloride, alkylbenzyldimethylammonium chloride), alkylpyridinium salts (for example, cetylpyridinium chloride) and the like.

Amphoteric surfactants include alkylbetaine types (for example, lauric betaine (lauryldimethylaminoacetic acid betaine, stearylbetaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine), amine oxide type (for example, lauryl). Dimethylamine oxide) and the like.
The addition amount of other structural surfactants not included in the surfactant A and the surfactant B in the present invention is 0.5 or less with respect to the total amount of the surfactant A and the surfactant B. Is preferred.

<(C) Oxidizing agent>
The metal polishing liquid of the present invention contains an oxidizing agent that oxidizes the metal of the object to be polished.
Examples of the oxidizing agent include hydrogen peroxide, peroxodisulfate, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, and perchlorate. Persulfates, dichromates, permanganates, ozone water and silver (II) salts, iron (III) salts.

  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 Examples include -hydroxysalicylic acid, 3,5-dihydroxysalicylic acid, gallic acid, benzoic acid, maleic acid and the like, and aminopolycarboxylic acids and salts thereof.

  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 them, hydrogen peroxide, iodate, hypochlorite, chlorate, persulfate, and iron (III) organic complex salts are preferred, and preferred complex-forming compounds when using iron (III) organic complex salts 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-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl)- L-aspartic acid, β-alanine diacetic acid, methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid).

  Among the oxidizing agents, hydrogen peroxide, persulfate, and iron (III) ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N A complex of '-tetraacetic acid and ethylenediamine disuccinic acid (SS form) is most preferred.

  The addition amount of the oxidizing agent is preferably in the range of 0.003 mol to 8 mol, more preferably in the range of 0.03 mol to 6 mol, per liter of the metal polishing liquid used for polishing. A range of 1 mol to 4 mol is particularly preferable. That is, the addition amount of the oxidizing agent is preferably 0.003 mol or more from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and is preferably 8 mol or less from the viewpoint of preventing roughening of the polished surface.

  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.

<(D) Organic acid>
The metal polishing slurry according to the present invention further contains at least one organic acid. The organic acid here is not a metal oxidizing agent, but has an action of promoting oxidation, adjusting pH, and buffering agent.
Examples of organic acids include organic acids and amino acids.

The organic acid is preferably water-soluble. Those selected from the following group are 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 Acid, tartaric acid, citric acid, lactic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, acedamidoiminodiacetic acid, nitrilotripropanoic acid, nitrilotrimethylphosphonic acid, dihydroxyethylglycine, tricine, and ammonium salts and alkali metals thereof Examples thereof include salts such as salts, ammonium salts, and mixtures thereof.

Moreover, as an amino acid, a water-soluble thing is preferable. Those selected from the following group are more suitable.
That is, 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 Acid, L-asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-kynurenine, L-histidine, 1-methyl-L-histidine, Examples include 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II, and antipine.

In the present invention, among the above organic acids or amino acids, it is particularly preferable to use the following aminocarboxylic acids.
That is, glycine, iminodiacetic acid, methyliminodiacetic acid, n-methylglycine, nitrilotripropanoic acid, hydroxyethyliminodiacetic acid, β-alanine, glycylglycine, dihydroxyethylglycine, acedamidoiminodiacetic acid, tricine, etc. is there.

In the metal polishing slurry of the present invention, the organic acids may be used alone or in combination of two or more.
These organic acids can be synthesized according to a conventional method, or commercially available products may be used.

  The addition amount of the organic acid is preferably 0.005 to 0.5 mol, more preferably 0.01 to 0.3 mol in 1 L of the metal polishing liquid used for polishing. It is especially preferable to set it as 05-0.3 mol. That is, the addition amount of the organic acid is preferably 0.005 mol or more from the viewpoint of improving the polishing rate, and preferably 0.5 mol or less from the viewpoint of not worsening dishing.

  Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, and among the inorganic acids, sulfuric acid, nitric acid, and phosphoric acid are preferable.

  The addition amount of the inorganic acid is preferably 0.005 to 0.5 mol, more preferably 0.03 to 0.3 mol in 1 L of the metal polishing liquid used for polishing. It is especially preferable to set it as 05-0.3 mol. That is, the addition amount of the inorganic acid is preferably 0.005 mol or more from the viewpoint of improving the polishing rate, and 0.5 mol or less is preferable from the viewpoint of not deteriorating dishing.

[PH]
In the present invention, the timely pH is set according to the adsorptivity and reactivity to the polishing surface, the solubility of the polishing metal, the electrochemical properties of the surface to be polished, the dissociation state of the compound functional group, the stability as a liquid, etc. It is preferable.
The pH of the metal polishing slurry of the present invention is preferably 3 to 10, preferably 4 to 9, and more preferably 6 to 8. In this range, the metal polishing slurry of the present invention exhibits particularly excellent effects. The polishing liquid of the present invention may be in a form that does not contain water. In this case, the above pH represents a value when the metal polishing liquid of the present invention is dissolved in water in a state used for polishing.

<(E) Heterocyclic compound>
Moreover, in this invention, the following (E) heterocyclic compound conventionally used as a corrosion inhibitor of metal polishing liquid is used together.
(E) As heterocyclic compounds, 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1H-tetrazole -5-acetic acid, 1H-tetrazole-5-succinic acid, 1,2,3-triazole, 4-amino-1,2,3-triazole, 4,5-diamino-1,2,3-triazole, 4- Carboxy-1H-1,2,3-triazole, 4,5-dicarboxy-1H-1,2,3-triazole, 1H-1,2,3-triazole-4-acetic acid, 4-carboxy-5-carboxy Methyl-1H-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-carboxy- 1,2,4-G Azole, 3,5-dicarboxy-1,2,4-triazole, 1,2,4-triazole-3-acetic acid, 1H-benzotriazole, 1H-benzotriazole-5-carboxylic acid and the like.

  Particularly preferred among the above compounds are 1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 1H-tetrazole- 5-acetic acid, 1H-tetrazole-5-succinic acid and the like.

<Abrasive grains>
The metal-polishing liquid of the present invention can contain abrasive grains. Examples of preferable abrasive grains include silica (precipitated silica, fumed silica, colloidal silica, synthetic silica), ceria, alumina, titania, zirconia, germania, manganese oxide, silicon carbide, polystyrene, polyacryl, polyterephthalate, and the like. It is done.
The abrasive grains are preferably particles having an average particle diameter of 5 to 1000 nm, particularly preferably 10 to 200 nm.
The addition amount when using abrasive grains is preferably 0.01 to 20% by mass, and in the range of 0.05 to 5% by mass, based on the total mass of the metal polishing liquid used. Is more preferable. 0.01% by mass or more is preferable for obtaining a sufficient effect in improving the polishing rate and reducing variation in the polishing rate within the wafer surface, and 20% by mass or less is preferable because the polishing rate by CMP is saturated.

[Raw metal materials]
In the present invention, the semiconductor to be polished is preferably an LSI having wiring made of copper metal and / or copper alloy, and particularly preferably a copper alloy. Furthermore, the copper alloy containing silver is preferable among 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 most preferably in the range of 0.00001 to 0.1% by mass. Exhibits excellent effects.

[Wiring thickness]
In the present invention, the semiconductor to be polished is, for example, a DRAM device system having a half pitch of 0.15 μm or less, particularly 0.10 μm or less, more preferably 0.08 μm or less, while MPU device system is 0.12 μm or less. In particular, an LSI having a wiring of 0.09 μm or less, more preferably 0.07 μm or less is preferable. The polishing liquid of the present invention exhibits particularly excellent effects on these LSIs.

[Barrier metal]
In the present invention, it is preferable to provide a barrier layer for preventing the diffusion of copper between the wiring in which the semiconductor is made of copper metal and / or a copper alloy and the interlayer insulating film. As the barrier layer, a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, WN, and Ru are particularly preferable, and Ta and TaN are particularly preferable.

[Polishing method]
The metal polishing liquid is a concentrated liquid, and when used, it is diluted with water to make a working liquid, or each component is mixed in the form of an aqueous solution described in the next section, and water is added if necessary. In some cases, it is used as a working solution after dilution. The polishing method using the metal polishing liquid of the present invention can be applied to any case, and the polishing liquid is supplied to the polishing pad on the polishing surface plate and brought into contact with the surface to be polished to thereby connect the surface to be polished and the polishing pad. This is a polishing method in which polishing is performed by relative movement.
As an apparatus for polishing, there is a general polishing apparatus having a polishing surface plate with a holder for holding a semiconductor substrate having a surface to be polished and a polishing pad attached (a motor etc. capable of changing the number of rotations is attached). Can be used. 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 substrate does not jump out. The pressure applied to the polishing pad of the semiconductor substrate having the surface to be polished (film to be polished) is preferably ⁵ to 500 g / cm ² in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern. Is more preferably 12 to 240 g / cm ² .

  During polishing, a polishing liquid for metal is continuously supplied to the polishing pad with 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 polishing, the semiconductor substrate is thoroughly washed in running water, and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. In the polishing method of the present invention, the aqueous solution to be diluted is the same as the aqueous solution described below. The aqueous solution is water that contains at least one of an oxidizing agent, an acid, an additive, and a surfactant in advance, and the total amount of the components contained in the aqueous solution and the components of the metal polishing liquid to be diluted is a metal. It becomes the component at the time of grinding | polishing using the polishing liquid. When diluted with an aqueous solution and used, components that are difficult to dissolve can be blended in the form of an aqueous solution, and a more concentrated metal polishing liquid can be prepared.

  As a method of diluting by adding water or an aqueous solution to the concentrated metal polishing liquid, the pipe for supplying the concentrated metal polishing liquid and the pipe for supplying the water or aqueous solution are joined together, mixed, mixed and diluted. There is a method of supplying the polished metal polishing liquid to the polishing pad. Mixing is a method in which 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 a pipe, and the flow of liquid is repeatedly separated and merged. Conventional methods such as a method of providing blades that rotate in the above can be employed.

  The supply rate of the metal polishing liquid is preferably 100 to 500 ml / min, and more preferably 150 to 300 ml / min in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern.

  As a method of diluting and polishing the concentrated metal polishing liquid with water or an aqueous solution, a pipe for supplying the metal polishing liquid and a pipe for supplying water or an aqueous solution are provided independently, and a predetermined amount of liquid is supplied from each. This is a method of polishing while supplying to the polishing pad and mixing by the relative movement of the polishing pad and the surface to be polished. Alternatively, there is a method in which a predetermined amount of concentrated metal polishing liquid and water or an aqueous solution are mixed in one container, and then the mixed metal polishing liquid is supplied to a polishing pad for polishing.

According to another polishing method of the present invention, a component to be contained in a metal polishing liquid is divided into at least two components, and when using them, a water or aqueous solution is added to dilute the polishing pad on a polishing platen. The surface to be polished is brought into contact with the surface to be polished, and the surface to be polished and the polishing pad are moved relative to each other for polishing.
For example, an oxidizing agent is one component (1), an acid, an additive, a surfactant, and water are one component (2), and when they are used, the component (1) Dilute component (2) for use.
Further, the low-solubility additive is divided into two components (1) and (2), and the oxidizing agent, additive and surfactant are one component (1), and the acid, additive, surfactant and Water is used as one component (2), and when they are used, water or an aqueous solution is added to dilute component (1) and component (2). In the case of this example, three pipes for supplying the component (1), the component (2), and water or an aqueous solution are required, and dilution mixing is performed on one pipe for supplying the three pipes to the polishing pad. There is a method of combining and mixing in the pipe. In this case, it is also possible to combine two pipes and then connect another pipe.

  For example, it is a method in which a component containing an additive that is difficult to dissolve is mixed with another component, a mixing path is lengthened to ensure a dissolution time, and then a pipe for water or an aqueous solution is further combined. Other mixing methods are as described above, in which the three pipes are each guided directly to the polishing pad and mixed by the relative movement of the polishing pad and the surface to be polished, and the three components are mixed in one container. A method for supplying a diluted metal polishing liquid to a polishing pad. In the above polishing method, one constituent component containing an oxidizing agent is made 40 ° C. or lower, the other constituent components are heated in the range of room temperature to 100 ° C., and one constituent component and another constituent component or water or an aqueous solution When the mixture is diluted and used, it can be adjusted to 40 ° C. or lower after mixing. Since the solubility increases when the temperature is high, this is a preferable method for increasing the solubility of the raw material having a low solubility in the metal polishing slurry.

  A raw material in which other components not containing an oxidizing agent are heated and dissolved in the range of room temperature to 100 ° C. is precipitated in the solution when the temperature is lowered. It is necessary to dissolve what is deposited by heating. For this, a means for feeding a heated component solution and a means for stirring the liquid containing the precipitate, feeding the liquid and heating and dissolving the piping can be employed. When the temperature of one component containing an oxidant is increased to 40 ° C. or higher, the oxidant may be decomposed. Therefore, the heated component and the oxidation for cooling the heated component When mixed with one component containing an agent, the temperature is set to 40 ° C. or lower.

  In the present invention, as described above, the component of the metal 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 the component containing an oxide and the component containing an acid. Alternatively, the metal polishing liquid may be a concentrated liquid, and the diluted water may be separately supplied to the polishing surface.

〔pad〕
The polishing pad 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.

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

Hereinafter, the present invention will be described by way of examples. The present invention is not limited to these examples.
(Examples 1-5 and Comparative Examples 1-3)
A polishing liquid was prepared with the composition shown below (Composition 1), and metal polishing liquids of Examples 1 to 7 and Comparative Examples 1 to 5 were obtained. Using each of these metal polishing liquids, evaluation was carried out by the following methods. The results are shown in Table 2.

(Composition 1)
Surfactant A Listed in Table 1 Surfactant B Listed in Table 1 30% Hydrogen peroxide [Oxidizing agent] 10 g / L
Glycine [organic acid] 10g / L
Benzotriazole [heterocyclic compound] 100 mg / L
Colloidal silica (average particle size 30 nm: abrasive grains) 5 g / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and nitric acid) pH 7.0

(Evaluation methods)
1. Polishing rate A device “FREX-300” manufactured by Ebara Corporation was used as a polishing device, and the film provided on each wafer was polished while supplying slurry under the following conditions, and the polishing rate was calculated.

・ Base: Silicon wafer with 12 inch copper film ・ Table rotation speed: 104 rpm
-Head rotation speed: 105 rpm
(Processing linear velocity = 1.0 m / s)
・ Polishing pressure: 10.5kPa
Polishing pad: Product number IC-1400 manufactured by Rohm and Haas
(K-grv) + (A21)
・ Slurry supply rate: 190 ml / min

The film thickness was converted from the electrical resistance before and after polishing. Specifically, it measured using the following formula.
Polishing rate (nm / min) = (thickness of copper film before polishing−thickness of copper film after polishing) / polishing time

2. Dishing, erosion Dishing, erosion evaluation substrate is formed by patterning a silicon oxide film 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. A 12-inch wafer was used in which a Ta film having a thickness of 20 nm was formed by a sputtering method, a copper film having a thickness of 50 nm was subsequently formed by a sputtering method, and a copper film having a total thickness of 1000 nm was formed by a plating method. .
This substrate is polished under the following conditions while supplying slurry onto a polishing cloth of a polishing surface plate of a polishing apparatus (equipment “FREX-300” manufactured by Ebara Seisakusho), and 100 μm / 100 μm Line / Space with 30% overpolish. The step was measured with a stylus type step meter to obtain dishing.
Further, the erosion was determined by measuring the step in 0.5 μm / 0.5 μm Line / Space with 30% overpolish using a stylus type step gauge.

  As the sucrose fatty acid monoester in Table 1, DK ester SS manufactured by Daiichi Kogyo Seiyaku Co., Ltd., which is a mixture of stearic acid ester / palmitic acid ester = 70/30 (mass ratio), was used. The 50:50 (mass ratio) mixture of sucrose fatty acid monoester and sucrose fatty acid di / tri / polyester is a mixture of stearic acid ester / palmitic acid ester = 70/30 (mass ratio). DK ester F-110 produced was used.

  From Table 2, Examples 1-7 of this invention do not reduce the polishing rate of copper by using surfactant A and surfactant B together, and dishing and erosion are small, and flatness is low. It turns out that it is favorable. In particular, Examples 1 to 5 in which the ratio of the content of surfactant A / surfactant B is within the range of 0.3 to 10 are good because the erosion is further small. In contrast, Comparative Example 1 and Comparative Example 2 lacking either surfactant A or surfactant B had large dishing and poor flatness. Further, Comparative Example 3 and Comparative Example 4 in which the surfactant A not having the HLB value of the surfactant A in the range of 12 to 18 and the surfactant B are used together have large erosion and poor flatness. there were. Further, Comparative Example 5 using an anionic surfactant not in the scope of the present invention as the surfactant B had a large erosion.

Claims (6)

  (A) A group consisting of a nonionic surfactant having a poly (oxyalkylene) group in the molecule and an HLB value in the range of 12 to 18, (B) sucrose fatty acid ester and alkyl (poly) glucoside For metal for chemical mechanical planarization of a semiconductor device containing one or more nonionic surfactants selected from (C) an oxidizing agent, (D) an organic acid, and (E) a heterocyclic compound Polishing fluid.   The content of the nonionic surfactant (A) having a poly (oxyalkylene) group in the molecule and an HLB value in the range of 12 to 18 is (a), and (B) the sucrose fatty acid. When the content of one or more nonionic surfactants selected from esters or alkyl (poly) glucosides is (b), the mass ratio (a) / (b) is 0.3 to 10 The metal polishing slurry according to claim 1, which is in a range.   The metal polishing slurry according to claim 1 or 2, wherein the sucrose fatty acid ester contains a sucrose fatty acid monoester.   The metal polishing liquid according to any one of claims 1 to 3, wherein the alkyl (poly) glucoside is selected from decyl glucoside and lauryl glucoside.   The metal polishing liquid according to any one of claims 1 to 4, wherein the metal polishing liquid is mainly used for polishing copper wiring in chemical mechanical planarization of a semiconductor device.   The metal polishing liquid according to any one of claims 1 to 5 is supplied to a polishing pad on a polishing surface plate and the polishing surface plate is rotated to rotate the polishing surface plate. A chemical mechanical polishing method in which polishing is performed by making a relative movement while being in contact with a polishing surface.