JP2008288537A - Polishing solution for metal and chemical mechanical polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution for metal having a quick copper polishing speed and good copper/tantalum polish selectivity and capable of enhancing planarity by reducing the dishing. <P>SOLUTION: The polishing solution for metal used for chemical mechanical polishing in the wiring process of a semiconductor device contains (A) an oxidizing agent, (B) an organic acid, (C) abrasive grains and (D) a trivalent iron compound in the range of 0.1 ppb-50 ppm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

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

In the practical application of semiconductor devices represented by semiconductor integrated circuits (hereinafter referred to as LSI), high density and high integration are required by miniaturization and stacking of wiring for miniaturization and high speed. In recent years, LSIs using copper having low wiring resistance as a metal for wiring have been developed, and various techniques such as chemical mechanical polishing (hereinafter referred to as CMP) have been used as techniques for this purpose. .
CMP is a technique for flattening the unevenness of the wafer surface caused by the lamination. Generally, a polishing pad is attached on a circular polishing surface plate (platen), and the surface of the polishing pad is immersed in a polishing liquid to be applied to the pad. The surface of the substrate (wafer) is pressed and a predetermined pressure (polishing pressure) is applied from the back side, and both the polishing platen and the substrate are rotated, and the surface of the substrate is flattened by the generated mechanical friction. It is.

As a liquid for polishing a metal such as a copper wiring, a liquid containing abrasive grains (for example, alumina, silica) and an oxidizing agent (for example, hydrogen peroxide) is generally used. It is thought that it is grind | polishing by removing the oxide film with an abrasive grain.
Conventionally, in CMP, a polishing scratch (scratch), a phenomenon in which the entire polishing surface is polished more than necessary (thinning), and the polishing metal surface is not flat but only the center is deeply polished, resulting in a dish-like depression. Problems such as the phenomenon (dishing) and the phenomenon that the insulator between metal wiring is polished more than necessary and the surface of multiple wiring metal surfaces form dish-shaped recesses (erosion) may occur. It has been broken.

  In particular, in recent years, the demand for reducing dishing due to the difference in polishing rate between the central portion and the peripheral portion of the wafer accompanying the increase in the wafer diameter has been increasing. Furthermore, recently, there is a demand for a method capable of obtaining a sufficient polishing rate even when polishing is performed under a low pressure so that film peeling does not occur even when an insulating material having low mechanical strength is used.

  In order to solve such a problem, 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, Patent Document 1). ,reference). According to this method, although a conductor pattern in which the metal film is left in the concave portion is obtained, there is a problem that it is difficult to obtain a sufficient polishing rate. In addition, a metal-polishing liquid containing a water-soluble oxidant such as phosphovanadmolybdic acid and a nonionic surfactant and not using abrasive grains is disclosed (for example, see Patent Document 2). The effect on the dishing phenomenon is insufficient.

  It is also known that copper metal polishing is particularly soft metal, so that dishing, erosion and scratches are likely to occur, and a phenomenon (slit) in which a groove is formed in the wiring metal in contact with the barrier metal is known. Accordingly, there is an increasing demand for highly accurate polishing technology.

  Further, when copper wiring is used, a diffusion preventing layer called a barrier layer is generally provided between the wiring portion and the insulating layer for the purpose of preventing the copper ions from diffusing into the insulating material, which is TaN, TaSiN, Ta, It is made of one layer or two or more layers selected from TiN, Ti, Nb, W, WN, Co, Zr, ZrN and CuTa alloy.

However, since these barrier materials themselves have conductive properties, the barrier material on the insulating layer must be completely removed to prevent the occurrence of errors such as leakage current. This is achieved by a method similar to bulk polishing (barrier CMP). Since dishing is likely to occur particularly in a wide metal wiring portion in bulk polishing of copper, it is desirable that the amount of polishing and removal in the wiring portion and the barrier portion can be adjusted in order to achieve final planarization. For this reason, it is desired that the polishing liquid for barrier polishing has an optimum copper / barrier metal polishing selectivity. Further, since the wiring pitch and the wiring density are different in each level of the wiring layer, it is further desirable that the polishing selectivity can be adjusted as appropriate.
JP 2001-127019 A JP 2003-173990 A

  The present invention has been made in order to increase the productivity of LSIs and to realize faster polishing of wirings made of copper metal and copper alloy as raw materials. That is, the main object of the present invention is to provide a polishing capable of providing a rapid polishing speed and good copper / barrier metal polishing selectivity to copper wiring, and further improving flatness with less dishing. To provide liquid.

As a result of intensive studies on the problems associated with the above-described metal polishing liquid, the present inventors have found that the problems can be solved by using the following abrasives and polishing methods, and have achieved the above-described problems.
That is, the present invention is as follows.
<1> A wiring process for a semiconductor device comprising (A) an oxidizing agent, (B) an organic acid, and (C) abrasive grains, and (D) a trivalent iron compound in a range of 0.1 ppb to 50 ppm. Polishing liquid for metals used for chemical mechanical polishing in Japan.
<2> The metal polishing slurry according to <1>, further comprising (E) tetrazole or a derivative thereof.
<3> In a semiconductor device manufacturing process, the metal polishing liquid according to <1> or <2> is brought into contact with a surface to be polished of a substrate having a conductor film made of copper or a copper alloy, and the surface to be polished of the substrate A chemical-mechanical polishing method, wherein polishing is performed by relatively moving the polishing surface of the polishing pad. In the metal polishing liquid of the present invention, the trivalent iron compound accelerates the oxidation reaction by containing the specified amount of the (D) trivalent iron compound together with the oxidizing agent and the organic acid. It is considered that the polishing rate increases.

In the present invention, the “metal polishing liquid” means not only a polishing liquid having a composition (concentration) used for polishing, but also a polishing concentrated liquid used by diluting as necessary during use, unless otherwise specified in the present invention. This is called polishing liquid. When the concentrated liquid is used for polishing, it is diluted with water or an aqueous solution and used for polishing, and the dilution ratio is generally 1 to 20 volume times.
In this specification, “concentration” and “concentrated liquid” are used in accordance with conventional expressions meaning “thick” and “thick liquid” rather than the state of use, and generally involve physical concentration operations such as evaporation. The term is used in a different way from the meaning of common terms.

  According to the present invention, there is provided a metal polishing liquid that exhibits a rapid polishing rate and good copper / barrier metal polishing selectivity with respect to copper wiring, and that can improve flatness with less dishing. Provided.

Hereinafter, specific embodiments of the present invention will be described.
The metal polishing liquid used in the present invention is a metal polishing liquid used for chemical mechanical polishing in the wiring process of a semiconductor device, and includes (A) an oxidizing agent, (B) an organic acid, and (C) abrasive grains. And (D) a trivalent iron compound in a range of 0.1 ppb to 50 ppm, preferably (E) tetrazole or a derivative thereof.
Hereinafter, a polishing liquid according to the present invention and a method for polishing a substrate for a semiconductor integrated circuit provided with a copper wiring using the polishing liquid will be described in detail.
First, (D) the trivalent iron compound, which is a characteristic component in the metal polishing slurry of the present invention, will be described.

<(D) Trivalent iron compound>
The polishing liquid of the present invention contains a trivalent iron compound. Examples of the trivalent iron compound include trivalent iron ions.
Specific examples of the trivalent iron compound used in the present invention include ammonium iron (III) hexacyanoferrate (II), iron (III) oxide, dodecairon nonadecaoxide salt, iron (III) hydroxide, Iron (III) ethoxide, iron nitride, iron disulfide, iron silicide, iron disilicide, triiron phosphide, iron (III) fluoride, iron (III) chloride, iron (III) bromide, iron iodide (III), iron oxalate ((III), iron (III) trifluoromethanesulfonate, iron (III) gluconate, iron (III) acrylate, iron (III) hypophosphite, iron (III) phosphate , Iron (III) diphosphate, iron (III) nitrate, iron (III) sulfate, iron (III) perchlorate, iron (III) 2-ethylhexanoate, iron cacodylate, iron (III) citrate, Iron (III) sulfamate, iron acetate ( II), iron tetrafluoroborate (II), ammonium iron citrate (III), ammonium iron sulfate (II), ammonium iron sulfate (III), ammonium iron oxalate (III), hexacyanoiron (III) salt, hexafluoroiron salt , Tris (oxalate) iron (III) salt, pentacyanonitrosyliron (III) salt, trifluoroacetylacetonatoiron (III),

Iron (III) acetylacetonate, cyclopentadienyl iron (I) dicarbonyl dimer, cyclohexadiene iron tricarbonyl, cyclooctatetraene iron tricarbonyl, pentamethylcyclopentadienyl iron dicarbonyl dimer, meso-tetra Phenylporphine iron (III) -μ-oxo dimer, meso-tetraphenylporphine iron (III) salt, bis (ethylcyclopentadienyl) iron, bis (isopropylcyclopentadienyl) iron, bis (tetramethylcyclopentadi) Enyl) iron, nonacarbonyl iron, dodecacarbonyl iron, dodecacarbonyl triiron (0), ethylenediamine-N, N, N ′, N′-tetraacetate iron (III) salt, cyclopentadienyl iron (I) dicarbonyl di amount Body, chloro (phthalocyaninato) iron (II ), Chloro (2,3,7,8,12,13,17,18-octaethylporphyrinato) iron (III), tris (5,6-diamino-κN-naphthalene-1,3-disulfonato) iron ( III) salts, tris (2,2,6,6-tetramethyl-3,5-heptanedionato) iron (III) and the like.

  Among these, preferably, iron (III) nitrate, iron (III) sulfate, iron (III) chloride, iron (III) bromide, iron (III) fluoride, iron (III) phosphate, diphosphate Iron (III), iron hypophosphite (III), iron perchlorate (III), iron hydroxide (III), iron oxide (III), iron nitride (III), iron sulfide (III), iron disulfide , Iron silicide, iron disilicate, ferric phosphide, iron (III) oxalate, iron (III) acetate, iron (III) citrate, iron (III) lactate, iron (III) naphthenate, fumaric acid Iron (III), iron (III) stearate, iron (III) sulfamate, iron (III) trifluoromethanesulfonate, iron (III) acrylate, ammonium iron (III) hexacyanoferrate (II), ammonium citrate Iron (III), ammonium sulfate Nitrogen iron (III), ammonium iron sulfate (III), ammonium iron oxalate (III), hexacyanoiron (III) salt, hexafluoroiron salt, tris (oxalic acid) iron (III) salt, pentacyanonitrosyl iron (III) Salt, pentacyanoammine iron (III) salt, trifluoroacetylacetonate iron (III), ethylene diammonium iron sulfate (II), iron (III) ethoxide, iron (III) acetylacetonate, ethylenediamine-N, N, N ′, N′-iron tetraacetate (III) salt and the like, more preferably, iron (III) nitrate, iron (III) perchlorate, iron (III) oxide, iron (III) oxalate, acetic acid Iron (III), iron (III) citrate, iron (III) lactate, iron (III) trifluoromethanesulfonate, iron gluconate ( II), acrylic iron (III), iron fumarate (III), an iron stearate (III), sulfamic iron (III), particularly preferably iron nitrate (III).

In addition, when divalent iron ions are added as an iron component, trivalent iron ions are formed by the influence of the coexisting (A) oxidizing agent in the metal polishing liquid. It is also possible to add it as a raw material (precursor) of the iron compound.
Examples of the divalent iron compound used for such purpose include iron oxide (II), iron chloride (II), iron bromide (II), iron iodide (II), iron oxalate (II), trifluoromethane. Iron (II) sulfonate, iron (II) gluconate, iron (II) sulfate and salts thereof, iron (II) perchlorate, iron (II) lactate, iron (II) naphthenate, iron (II) fumarate , Iron (II) stearate, iron (II) sulfamate, iron (II) acetate, iron (II) tetrafluoroborate, iron (II) ammonium sulfate, hexacyanoiron (II) salt, pentacyanoammine iron (II) salt (Tetra-t-butylphthalocyaninato) iron (II), (tetracarboxyphthalocyaninato) iron (II), ethylenediammonium iron sulfate (II) and the like.
Among them, preferably, iron (II) oxide, iron (II) sulfide (II) iron chloride (II) iron bromide (II), iron (II) iodide, iron (II) oxalate, iron (II) trifluoromethanesulfonate (II) ), Iron (II) gluconate, iron (II) sulfate and salts thereof, iron (II) perchlorate, iron (II) lactate, iron (II) naphthenate, iron (II) fumarate, iron stearate ( II), iron (II) sulfamate, iron (II) acetate, iron (II) tetrafluoroborate, iron (II) sulfate, hexacyanoiron (II) salt, pentacyanoammine iron (II) salt, ethylenediammonium sulfate Iron (II), and more preferably iron (II) oxide, iron (II) oxalate, iron (II) trifluoromethanesulfonate, iron (II) gluconate, iron (II) perchlorate, lactic acid Iron (II , Iron fumarate (II), an iron stearate (II), sulfamic iron (II), iron acetate (II).

Only one type of trivalent iron compound may be used, or two or more types may be used in combination. Moreover, as a compound added according to the objective, a trivalent iron compound and a divalent iron compound can also be used together.
The content of the trivalent iron compound contained in the metal polishing slurry of the present invention is required to be in the range of 0.1 ppb to 50 ppm. If the content is too small, the effect is insufficient, and if the content is too large, the pot life is deteriorated. The content is preferably from 0.1 ppb to 10 ppm, more preferably from 0.1 ppb to 1 ppm, and particularly preferably from 1 ppb to 100 ppb.
Within this content range, an effective copper polishing rate improvement effect can be obtained, and there is no concern of impairing flatness.
The content of the trivalent iron compound in the metal polishing slurry can be measured by a known method such as a high frequency inductively coupled plasma (ICP) method.

Next, although the other component of the metal polishing liquid of this invention is explained in full detail, each component may use only 1 type and may use 2 or more types together.
<(A) Oxidizing agent>
The metal polishing liquid of the present invention contains a compound (oxidant) that can oxidize a metal to be polished.
Specifically, hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, dichromium Acid salts, permanganates, ozone water and silver (II) salts are mentioned, and hydrogen peroxide is more preferably used. These may be used individually by 1 type and may use 2 or more types together.

  The addition amount of the oxidizing agent is preferably 0.003 mol to 8 mol, more preferably 0.03 mol to 6 mol, and more preferably 0.1 mol to 4 mol in 1 liter of the metal polishing liquid used for polishing. It is particularly preferable to do this. 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.

<(B) Organic acid>
The metal polishing slurry of the present invention contains an organic acid, and the organic acid promotes copper elution. Examples of the organic acid include amino acids and other acids.
As the organic acid, one selected from the following group is suitable. Suitable organic acids for the present invention include 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-methylhexanoic 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, malic acid, tartaric acid, citric acid, lactic acid, and amino acids (amino acids include primary, secondary, tertiary amino acids and aminopolycarboxylic acids. Is preferred.

As the amino acid, one selected from the following group is more suitable.
Glycine, sarcosine, L-alanine, β-alanine, L-2-aminobutyric acid, L-norvaline, L-valine, L-leucine, L-norleucine, L-isoleucine, L-alloisoleucine, L-phenylalanine, L- Proline, 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- (carboxymethyl) -L-cysteine, 4-aminobutyric acid, L Asparagine, L-glutamine, azaserine, L-arginine, L-canavanine, L-citrulline, δ-hydroxy-L-lysine, creatine, L-quinurenin, L-histidine, 1-methyl-L-histidine, 3-methyl -Amino acids such as L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II and antipine.
In addition, specific amino acids having a hydroxyethyl group described in Japanese Patent Application No. 2006-269410 previously filed by the applicant of the present application can also be used in the present invention.
Furthermore, the compounds represented by the following general formula (1) and general formula (2), and ammonium salts and alkali metal salts thereof are exemplified.

In general formula (1), R ¹ represents a single bond, an alkylene group, or a phenylene group. R ² and R ³ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁴ and R ⁵ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group. However, when R ¹ is a single bond, at least one of R ⁴ and R ⁵ is not a hydrogen atom.

The alkylene group as R ¹ in the general formula (1) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, and examples thereof include a methylene group and an ethylene group. Can do. Examples of the substituent that the alkylene group may have include a hydroxyl group and a halogen atom.

The alkyl group as R ² and R ³ preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group. The cycloalkyl group as R ² and R ³ preferably has 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The alkenyl group as R ² and R ³ preferably has 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group. The alkynyl group as R ² and R ³ preferably has 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.

The aryl group as R ² and R ³ preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group. The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom. Examples of the substituent that each group as R ² and R ³ may have include a hydroxyl group, a halogen atom, an aromatic ring (preferably having 3 to 15 carbon atoms), a carboxyl group, and an amino group.

The alkyl group as R ⁴ and R ⁵ preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group. The acyl group preferably has 2 to 9 carbon atoms, and examples thereof include a methylcarbonyl group. Examples of the substituent that each group as R ⁴ and R ⁵ may have include a hydroxyl group, an amino group, and a halogen atom.

In general formula (1), it is preferable that either one of R ⁴ and R ⁵ is not a hydrogen atom.
In the general formula (1), it is particularly preferable that R ¹ is a single bond, and R ² and R ⁴ are hydrogen atoms. In this case, R ³ represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group, and particularly preferably a hydrogen atom or an alkyl group. R ⁵ represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group, and an alkyl group is particularly preferable. As the substituent that the alkyl group as R ³ may have, a hydroxyl group, a carboxyl group, or an amino group is preferable. As the substituent that the alkyl group as R ⁵ may have, a hydroxyl group or an amino group is preferable.

In general formula (2), R ⁶ represents a single bond, an alkylene group, or a phenylene group. R ⁷ and R ⁸ each independently represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ⁹ represents a hydrogen atom, a halogen atom, a carboxyl group, or an alkyl group. R ¹⁰ represents an alkylene group. However, when R ¹⁰ is —CH ₂ —, R ⁶ is not a single bond or R ⁹ is not a hydrogen atom.

The alkylene group as R ⁶ and R ¹⁰ in the general formula (2) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, such as a methylene group or an ethylene group. Can be mentioned. Examples of the substituent that the alkylene group and the phenylene group may have include a hydroxyl group and a halogen atom.

The alkyl group as R ⁷ and R ⁸ preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group. The cycloalkyl group as R ⁷ and R ⁸ preferably has 5 to 15 carbon atoms, and examples thereof include a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group. The alkenyl group as R ⁷ and R ⁸ preferably has 2 to 9 carbon atoms, and examples thereof include a vinyl group, a propenyl group, and an allyl group. The alkynyl group as R ⁷ and R ⁸ preferably has 2 to 9 carbon atoms, and examples thereof include an ethynyl group, a propynyl group, and a butynyl group.

The aryl group as R ⁷ and R ⁸ preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group. The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom. Examples of the substituent that each group as R ⁷ and R ⁸ may have include a hydroxyl group, a halogen atom, and an aromatic ring (preferably having 3 to 15 carbon atoms).

The alkyl group as R ⁹ preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group. The acyl group as R ⁹ preferably has 2 to 9 carbon atoms, and examples thereof include a methylcarbonyl group. The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom. Examples of the substituent that each group as R ⁹ may have include a hydroxyl group, an amino group, a halogen atom, and a carboxyl group.
In the general formula (2), R ⁹ is preferably not a hydrogen atom.

  Hereinafter, specific examples (X-1 to X-27) of the organic acid represented by the general formula (1) and specific examples (Y-1 to Y-11) of the organic acid represented by the general formula (2) However, it is not limited to these.

Although the compound represented by General formula (1) or (2) can be synthesize | combined by a well-known method, you may use a commercially available thing.
In particular, as an organic acid, an amino acid derivative containing the compound represented by the general formula (1) and the compound represented by the general formula (2) effectively suppresses the etching rate while maintaining a practical CMP rate. It is preferable in that it can be performed.

As organic acids other than amino acids, those selected from the following group are more suitable.
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-methylhexanoic 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, malic acid, Examples thereof include tartaric acid, citric acid, lactic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine, and salts such as ammonium salts and alkali metal salts thereof.
Among these, formic acid, malonic acid, malic acid, tartaric acid, citric acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine, etc. effectively maintain the etching rate while maintaining a practical CMP rate. This is preferable in that it can be suppressed.
As these organic acids, organic acids obtained by synthesis are preferable to natural products from the viewpoint of uniformity of physical properties and stability of effects.

  The amount of the organic acid used in the present invention is the polishing liquid used for polishing (that is, the metal polishing liquid after dilution when diluted with water or an aqueous solution. "Liquid" is also consent.) In 1 L of 0.005 to 0.5 mol, preferably 0.005 to 0.3 mol, more preferably 0.01 to 0.1 mol. Particularly preferred. That is, the addition amount of the organic acid is preferably 0.5 mol or less from the viewpoint of suppressing etching, and 0.0005 mol or more is preferable for obtaining a sufficient effect.

<(C) Abrasive grain>
The metal polishing liquid of the present invention contains 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. In particular, when colloidal silica is used, the remarkable effect of the present invention is obtained, which is preferable.

  Further, the abrasive used in the metal polishing slurry of the present invention is colloidal silica in which at least some of the silicon atoms on the surface are substituted with aluminum atoms (hereinafter sometimes referred to as specific colloidal silica as appropriate). preferable.

  As a method for producing such abrasive grains, for example, a method of adding an aluminate compound such as sodium aluminate to a dispersion of colloidal silica (Japanese Patent No. 3463328, Japanese Patent Laid-Open No. 63-123807), or an aluminum alkoxide is added. The method is known.

  “Colloidal silica in which at least some of the silicon atoms on the surface are substituted with aluminum atoms” means that the aluminosilicate site generated by the reaction between tetracoordinate aluminate ions and silanol groups on the surface of the colloidal silica has a negative charge. By fixing and giving a large negative zeta potential to the particles, it is excellent in dispersibility even in acidity. Therefore, it is important that the aluminum atoms exist in a state coordinated with four oxygen atoms.

  Such a structure, that is, the occurrence of substitution of silicon atoms and aluminum atoms on the colloidal silica surface can be easily confirmed, for example, by measuring the zeta potential of the abrasive grains.

The amount of substitution of silicon atoms on the surface of colloidal silica with aluminum atoms is such that the surface atom substitution rate (number of introduced aluminum atoms / number of surface silicon atom sites) of colloidal silica is preferably 0.001% or more and 20% or less, and more preferably. Is from 0.01% to 10%, particularly preferably from 0.1% to 5%.
When the silicon atom on the surface of the colloidal silica is replaced with an aluminum atom, the substitution amount with the aluminum atom is controlled by controlling the addition amount (concentration) of an aluminate compound, aluminum alkoxide, etc. added to the colloidal silica dispersion. It can be appropriately controlled.

Here, the amount of aluminum atoms introduced into the surface of the colloidal silica (number of introduced aluminum atoms / number of surface silicon atom sites) is calculated from the diameter of the colloidal silica assuming that the aluminum compound added to the dispersion has reacted 100%. Surface area, specific gravity of colloidal silica of 2.2, and the number of silanol groups per unit surface area (5 to 8 / nm ² ). The actual measurement is based on elemental analysis of the obtained colloidal silica itself. Assuming that aluminum does not exist inside the particles and spreads uniformly and thinly on the surface, the surface area / specific gravity of the colloidal silica and the number of silanol groups per unit surface area are obtained.

As addition amount of an abrasive grain, it is preferable to contain 0.05-20g abrasive grain in 1L of metal polishing liquids at the time of use, and when 0.2-5g abrasive grain is included especially, the effect of this invention is included. Remarkably obtained and preferred.
Moreover, the average particle diameter of the abrasive grains is preferably 5 to 200 nm, and the use of abrasive grains having an average particle diameter of 20 to 70 nm is particularly preferable because the effects of the present invention are remarkably obtained.

<Other ingredients>
In addition to the essential components (A) to (D) described above, the metal polishing slurry of the present invention is selected according to the purpose as long as the effects of the present invention are not impaired. Can be added. These additives will be described.
[Chelating agent]
The polishing liquid of the present invention preferably contains a chelating agent (that is, a hard water softening agent) as necessary in order to reduce the adverse effects of mixed metal ions such as calcium and magnesium. The addition of the chelating agent has the advantage that the storage stability of the metal polishing liquid is improved.
Chelating agents include general water softeners and related compounds that are calcium and magnesium precipitation inhibitors, such as amino acids (eg, nitrilotriacetic acid derivatives, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid (EDTA), etc. Alkyldiaminetetraacetic acids, transcyclohexanediaminetetraacetic acid, 1,2-diaminopropanetetraacetic acid, glycol etherdiaminetetraacetic acid, ethylenediamine orthohydroxyphenylacetic acid, N, N′-bis (2-hydroxybenzyl) ethylenediamine-N, N '-Diacetic acid, ethylenediamine disuccinic acid (SS form), N- (2-carboxylate ethyl) -L-aspartic acid, β-alanine diacetic acid, etc.), organic / inorganic phosphoric acid compounds (for example, N, N, N -Trimethylene phosphonic acid, 2-phospho Nobutane-1,2,4-tricarboxylic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, etc.), alcohol compounds (for example, 8-quinolinol derivatives, catechol derivatives, N, N′-bissalicylidene-alkyldiamines, 1 , 2-dihydroxybenzene-4,6-disulfonic acid, kojic acid and the like) and sulfonic acid compounds (alkyldiamine-N, N, N ′, N′-tetramethylenesulfonic acid and the like). Of these, 2- (bis (carboxymethyl) amino) succinic acid, diethylenetriaminepentaacetic acid, 1,3-propanediaminetetraacetic acid, 1,4-butanediaminetetraacetic acid, N, N, N-trimethylene Phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, 8-quinolinol-5-sulfonic acid, 8-quinolinol-2-carboxylic acid, catechol, N, N′-bissalicylidene-1,3-propanediamine, Kojic acid, more preferably 2- (bis (carboxymethyl) amino) succinic acid, diethylenetriaminepentaacetic acid, 1,3-propanediaminetetraacetic acid, and 8-quinolinol-5-sulfonic acid.

Two or more chelating agents may be used in combination as necessary.
The addition amount of the chelating agent may be an amount sufficient to sequester metal ions such as mixed polyvalent metal ions. For example, in 1 L of polishing liquid (use liquid) used for polishing, 0.1 ppb to 10,000 ppm is preferable, 1 ppb to 1000 ppm is more preferable, and 10 ppb to 100 ppm is still more preferable.

[Compound having an aromatic ring (passive film forming agent)]
In the polishing liquid in the present invention, a compound having a function as a passive film forming agent that forms a passive film on the metal surface and controls the polishing rate, specifically, a compound having an aromatic ring (hereinafter, appropriately, May be used in combination.
As the compound having such a function, specifically, a heterocyclic compound described in paragraph No. [0016] of JP-A-2006-261333 can be used.
Preferred are tetrazole and derivatives thereof, 1,2,3-triazole and derivatives thereof, and 1,2,4-triazole and derivatives thereof, and benzotriazole and derivatives thereof. Among them, tetrazole and derivatives thereof have improved dishing. It is preferable from the viewpoint.

[(E) Tetrazole or its derivative]
A preferred combination component of the present invention, (E) tetrazole having a passive film-forming ability or a derivative thereof (in the specification, both may be collectively referred to as a tetrazole derivative) will be described.
Examples of the tetrazole derivative include a tetrazole derivative having, as a substituent, an alkyl group substituted with at least one of a carboxyl group, an amino group, a hydroxy group, or a carboxy group. More preferably, it is a tetrazole derivative characterized by containing at least one carboxy group or amino group.
Specific examples include 5-carboxy-1H-tetrazole, 1H-tetrazole-5-acetic acid, 1H-tetrazole-5-propionic acid, and 5-amino-1H-tetrazole.
Of these, tetrazole, 5-amino-1H-tetrazole and the like are preferable.

Hereinafter, (E) an aromatic ring compound other than tetrazole or a derivative thereof will be described.
Other preferred examples of the aromatic ring compound include triazole and derivatives thereof. As preferred triazole derivatives, 1,2,3-having a substituent selected from the group consisting of a hydroxy group, a carboxy group or an amino group, or an alkyl group substituted with at least one of these substituents as a substituent. And triazole derivatives. More preferably, it is a 1,2,3-triazole derivative characterized by containing at least one hydroxy group or an alkyl group substituted with at least one hydroxy group as a substituent.
Specific examples of the compound include 4-hydroxy-1H-1,2,3-triazole, 4-hydroxymethyl-1H-1,2,3-triazole, and 4-1H-1,2,3-triazole. It is done.

  Other preferable triazole derivatives include those substituted with a carboxyl group or a hydroxy group, or 1,2,4-triazole derivatives having an alkyl group substituted with at least one of a hydroxy group and a carboxy group as a substituent. More preferably, it is a 1,2,4-triazole derivative characterized by containing at least one alkyl group substituted with at least one carboxy group as a substituent. For example, 3-hydroxy-1,2,4-triazole, 3,5-dicarboxy-1,2,4-triazole, 1,2,4-triazole-3-acetic acid.

Examples of the triazole derivative include a benzotriazole derivative having, as a substituent, an alkyl group substituted with at least one of a carboxyl group, an amino group, a hydroxy group, or a carboxy group, and more preferably, at least one carboxy group or an alkyl group. And benzotriazole derivatives having a group.
Specific examples of the compound include 5-carboxy-benzotriazole and 5-methyl-benzotriazole.

A commercial item can also be used for these aromatic ring compounds. Moreover, it is also compoundable according to the following references.
Tetrazole derivatives are described in Chemische Berichte, 34, 3120 (1901), Chemische Berichte, 89, 2648, (1956), Chemische Berichte, 34, 3120 (1901), Chemische Berichte, 89, 2652, o, m , 29, 538-549 (1986), Carbohydrate Research, 73, 323-326 (1979), 1,2,3-triazole derivatives, Carbohydrate Research, 38, 107-115 (1974), Journal of Organic Chemistry, 21 , 190 (1956), 1,2,4-triazo Chemistry of Heterocyclic Compounds, 16, 199 (1979), Chemistry of Heterocyclic Compounds, 5, 121-122 (1969), Journal of Organic 1992, Journal of Organic Chemistry 32, 1969, Journal of Organic Chemistry. 31, 265, 272 (1966).

  The addition amount of the aromatic ring compound containing (E) tetrazole or a derivative thereof is preferably 0.00001 to 5 mol, more preferably 0.0001 to 0.00 in 1 liter of a metal polishing slurry used for polishing. 5 mol, more preferably 0.0005 to 0.5 mol.

〔Additive〕
Moreover, it is preferable to use the following additives for the polishing liquid of the present invention.
That is, for example, ammonia; alkylamines such as dimethylamine, trimethylamine, triethylamine, and propylenediamine; amines such as sodium diethyldithiocarbamate and chitosan; dithizone, cuproin (2,2′-biquinoline), neocuproin (2,9-dimethyl) -1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazones (biscyclohexanone oxalylhydrazone); nonyl mercaptans, dodecyl mercaptans, triazine thiols, triazines Examples include mercaptans such as dithiol and triazine trithiol, anthranilic acid, aminotoluic acid, and quinaldic acid.
Among these, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, and triazinedithiol are preferable for achieving both a high CMP rate and a low etching rate.

  The addition amount of these additives is preferably 0.0001 mol to 0.5 mol, more preferably 0.001 mol to 0.2 mol in 1 L of a polishing liquid (use liquid) when used for polishing. It is especially preferable to set it as 0.005 mol-0.1 mol. That is, the addition amount of the additive is preferably 0.0001 mol or more from the viewpoint of suppressing etching, and preferably 0.5 mol or less from the viewpoint of preventing a decrease in CMP rate.

[Surfactant, hydrophilic compound]
The polishing liquid of the present invention preferably contains a hydrophilic compound such as a surfactant and a hydrophilic polymer. Both the surfactant and the hydrophilic polymer have the action of reducing the contact angle of the surface to be polished and the action of promoting uniform polishing. As the surfactant and hydrophilic polymer to be used, those selected from the following group are suitable.

(Surfactant)
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt, and phosphate ester salt. More specifically, the carboxylate includes soap, N-acyl amino acid salt, polyoxyethylene. Or polyoxypropylene alkyl ether carboxylate, acylated peptide; as sulfonate, alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, naphthalene sulfonate, sulfosuccinate, α-olefin sulfonate, N- Acyl sulfonate; sulfate ester, sulfated oil, alkyl sulfate, alkyl ether sulfate, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfate, alkyl amide sulfate; alkyl phosphate as phosphate ester salt Salt, polyoxyethylene Or it can be given polyoxypropylene alkyl allyl ether phosphates.

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. More specifically, as ether type, polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxy Ethylene ether, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether; ether ether type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether ; As the ester type, polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol Glycol ester, sucrose esters; as nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like.
Moreover, a fluorine-type surfactant can also be used.

(Hydrophilic compound)
Examples of hydrophilic surfactants, hydrophilic compounds, and hydrophilic polymers that can be used in the present invention include esters such as glycerol 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 alk Ethers, such as polypropylene glycol alkenyl ether, alkyl polypropylene glycol, alkyl polypropylene glycol alkyl ether, alkyl polypropylene glycol alkenyl ether, alkenyl polypropylene glycol, alkenyl polypropylene glycol alkyl ether and alkenyl polypropylene glycol alkenyl ether; alginic acid, pectic acid, carboxymethyl cellulose, 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, polyamide Acid, polymalein , Polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), polyacrylic acid, polyacrylamide, aminopolyacrylamide, ammonium polyacrylate, sodium polyacrylate, polyamic acid, ammonium polyamic acid, sodium polyamic acid Salts and polycarboxylic acids such as polyglyoxylic acid and salts thereof; vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone and polyacrolein; methyl taurate ammonium salt, methyl taurate sodium salt, methyl sodium sulfate salt, ethyl ammonium sulfate salt, Butyl ammonium sulfate, vinyl sulfonic acid sodium salt, 1-allyl sulfonic acid sodium salt, 2-allyl sulfonic acid sodium salt, methoxymethyl sulfonic acid sodium salt, Sulphonic acid and its salts such as ammonium dimethyl sulfonate, sodium 3-ethoxypropyl sulfonate, sodium methoxymethyl sulfonate, ammonium ethoxymethyl sulfonate, sodium 3-ethoxypropyl sulfonate and sodium sulphosuccinate Amides such as propionamide, acrylamide, methylurea, nicotinamide, succinic acid amide and sulfanilamide;

Here, when the object to be polished is a silicon substrate for a semiconductor integrated circuit or the like, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable, so these compounds to be used together include acids or ammonium salts thereof. desirable.
This is not the case when the object to be polished is a glass substrate or the like.

Among the above-mentioned compounds, surfactants and hydrophilic compounds include cyclohexanol, ammonium polyacrylate, polyvinyl alcohol, succinic acid amide, polyvinyl pyrrolidone, polyethylene glycol, polyoxyethylene polyoxypropylene block polymer, polyoxyethylene. Alkyl (12-14) sulfosuccinate disodium, palm oil fatty acid methyl taurine sodium, sulfosuccinate (dioctyl type), polyoxyethylene coconut oil fatty acid sodium monoethanolamide sulfate, dodecyl diphenyl ether disulfonate, polyoxyethylene alkyl phenyl ether Palm oil fatty acid sarcosine triethanolamine, dodecylbenzenesulfonic acid triethanolamine, polyoxyethylene lauryl amine Le sulfate triethanolamine, diisobutyl dimethyl butanediol polyoxyethylene glycol ether, are more preferred.
The surfactant and the hydrophilic polymer can be used alone or in combination of two or more.

  The addition amount of the surfactant and / or the hydrophilic compound is preferably 0.001 to 10 g, and 0.01 to 5 g in 1 liter of a polishing liquid (use liquid) when used for polishing as a total amount. More preferably, it is 0.1-3 g. That is, the addition amount of the surfactant and / or the hydrophilic compound is preferably 0.001 g or more for obtaining a sufficient effect, and is preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered. In addition, the molecular weight of the surfactant or hydrophilic compound used and the weight average molecular weight of the hydrophilic polymer are preferably 500 to 100,000, and more preferably 2000 to 50,000.

[Alkaline agent and buffer]
The polishing liquid of the present invention can contain an alkali agent for pH adjustment and further a buffering agent from the viewpoint of suppressing pH fluctuations, if necessary.
As the alkali agent and buffer material, those described in paragraph numbers [0049] to [0053] of JP-A-2006-261333 can be used.

  The addition amount of the alkaline agent and the buffer may be an amount that maintains the pH within a preferable range, and is 0.0001 mol to 1.0 mol in 1 L of a polishing liquid (use liquid) when used for polishing. It is preferable that it is 0.003 mol-0.5 mol.

[Inorganic acid]
The metal polishing slurry of the present invention can contain an inorganic acid as necessary for the purpose of promoting oxidation, adjusting the pH, acting as a buffering agent, and the like.
Although it does not specifically limit as an inorganic acid, For example, perchloric acid, a sulfuric acid, nitric acid, boric acid etc. are mentioned, Especially, nitric acid is preferable.

(PH of metal polishing liquid)
In the present invention, the pH of the polishing liquid in a timely manner due 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. Is preferably set.
2-14 are preferable, as for pH of the polishing liquid (use liquid) at the time of using for grinding | polishing, 3-12 are more preferable, and 3.5-9 are the most preferable.
Within this range, the metal liquid of the present invention exhibits particularly excellent effects.
In order to adjust to such a predetermined pH, the alkali agent, buffer agent, inorganic acid and the like are appropriately selected and added to the metal polishing liquid of the present invention.

<Chemical mechanical polishing method>
Next, a chemical mechanical polishing method using the metal polishing liquid of the present invention will be described below.
The polishing liquid of the present invention is preferably a polishing liquid used when chemical mechanical polishing is performed on an excess copper film in order to form a copper wiring in a manufacturing process of a substrate for a semiconductor integrated circuit.
By using the polishing liquid of the present invention, a semiconductor integrated circuit substrate having copper wiring excellent in planarization can be obtained.

[Wafer (for polishing)]
An object to be polished by the polishing liquid of the present invention is a wafer for obtaining a substrate for a semiconductor integrated circuit having a copper wiring, and has a copper film. The material constituting the copper film (copper wiring) is preferably a copper metal and / or a 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, most preferably in the range of 0.00001 to 0.1% by mass. Exhibits excellent effects.

(Wiring thickness)
In the present invention, a semiconductor integrated circuit substrate obtained after polishing is, for example, a DRAM device system having a wiring with a half pitch of 0.15 μm or less, further 0.10 μm or less, particularly 0.08 μm or less. It is preferable to have it. On the other hand, in the MPU device system, it is preferably 0.12 μm or less, more preferably 0.09 μm or less, and particularly preferably a wiring having 0.07 μm or less.
The polishing liquid of the present invention exhibits a particularly excellent effect on a wafer having such a wiring thickness (a polishing target).

(Barrier metal)
In the present invention, the wafer to be polished preferably has a barrier layer for preventing copper diffusion between the copper wiring made of copper metal and / or a copper alloy and the interlayer insulating film or substrate. As the barrier layer, a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, and WN are particularly preferable, and Ta and TaN are particularly preferable.
Further, the interlayer insulating film, for example, SiO ₂ and the like.

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

<Specific polishing method in chemical mechanical polishing>
A method of performing chemical mechanical polishing of the copper film in the manufacturing process of the semiconductor integrated circuit substrate using the polishing liquid of the present invention is not particularly limited.
For example, it is common to have a holder for holding a wafer (substrate) to be polished having a surface to be polished, and a polishing surface plate to which a polishing pad is attached (a motor that can change the number of revolutions is attached). Polishing is performed by supplying the polishing liquid of the present invention to the polishing pad on the polishing surface plate and bringing the polishing surface into contact with the polishing surface of the substrate and causing the polishing surface and the polishing pad to move relative to each other. It is mentioned as a preferred embodiment.

The polishing liquid of the present invention is a preferred embodiment in its use. For example, when (1) a concentrated liquid is used and diluted with water or an aqueous solution when used, (2) each component is In the case of being prepared in the form of an aqueous solution described in the next section, mixing these, and diluting by adding water as necessary to obtain a working solution, (3) the case of being prepared as a working solution.
In the polishing method using the polishing liquid of the present invention, any of the preferred embodiments in the use of the polishing liquid of the present invention can be applied.

  As the polishing pad used in the polishing method using the polishing liquid of the present invention, those described in paragraph [0067] of JP-A-2006-261333 can be used.

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 wafer does not jump out.
The pressing pressure of the wafer having the surface to be polished (film to be polished) against the polishing pad is preferably ⁵ to 500 g / cm ² , and the uniformity of the polishing surface within the wafer surface and the flatness of the pattern are improved. In order to satisfy, it is more preferable that it is 12-240 g / cm < ² >.

During polishing, a polishing liquid 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.
The supply rate of this polishing liquid is preferably 10 to 1000 ml / min, more preferably 170 to 800 ml / min, in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern.
The wafer after polishing is thoroughly washed in running water, and then dried after removing water droplets adhering to the polishing surface using a spin dryer or the like.

In the present invention, when diluting the concentrate as in the method (1), the following aqueous solutions can be used. The aqueous solution is water containing at least one of an oxidizing agent, an organic acid, an additive, and a surfactant in advance, and the components contained in the aqueous solution and the concentrated solution to be diluted are contained. The component obtained by summing up the components being used is a polishing liquid used for polishing, that is, a component of the working liquid.
Thus, when the concentrate is diluted with an aqueous solution and used, components that are difficult to dissolve can be added later in the form of an aqueous solution, so that a more concentrated concentrate can be prepared.

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

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

As another polishing method, the component to be contained in the polishing liquid is divided into at least two components, and when using them, water or an aqueous solution is added and diluted and supplied to the polishing pad on the polishing platen, There is a method of polishing by bringing the surface to be polished and the polishing pad into relative motion while being brought into contact with the surface to be polished.
For example, an oxidizing agent is used as component (i), an organic acid, an additive, a surfactant, and water are used as component (ii). Component (ii) can be used diluted.
Further, the low-solubility additive is divided into two components (i) and (ii). For example, an oxidant, an additive, and a surfactant are the components (i), and an organic acid, an additive, Surfactant and water are used as the constituent component (ii), and water or an aqueous solution is added when using them, and the constituent component (i) and the constituent component (ii) are diluted and used.

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

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

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

  Thus, in the polishing method using the polishing liquid of 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 the component containing an oxide and the 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.

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

<Example 1>
A polishing liquid having the composition shown below was prepared, and the polishing liquid of Example 1 was obtained. This polishing liquid was evaluated by conducting a polishing test by the following method.

(Polishing liquid composition)
・ Hydrogen peroxide [(A) oxidizing agent] 4 g
・ Benzotriazole [passive film forming agent] 0.3g
Amino acid (Exemplary compound: X-4) [(B) Organic acid] ... 10 g
・ Iron nitrate (III) [(D) trivalent iron compound] 0.05 mg
(Concentration in metal polishing fluid: 5 ppm, trivalent iron content 1.2 ppm)
・ Colloidal silica [(C) Abrasive] ... 11g
-Pure water: The amount that the total amount becomes 1000 ml The pH of the polishing liquid was adjusted to 7.1 by using ammonia water and nitric acid.
The masses of the hydrogen peroxide, benzotriazole, organic acid, trivalent iron compound, and colloidal silica indicate the masses of these components themselves.

The content of heavy metal ions is determined by an inductively coupled plasma (hereinafter referred to as “ICP”) or an inductively coupled plasma mass spectrometer (hereinafter referred to as “ICP-”), which is a generally known measurement method. MS ”)).
In this example, the iron content derived from the trivalent iron compound contained in the prepared metal abrasive was confirmed by the following method. That is, the sample was dissolved in water, measured with ICPS-1000IV manufactured by Shimadzu Corporation, and the iron content was determined by an absolute calibration curve method.
The results are also shown in Table 1 below.

(Polishing test)
-Polishing pad: IC1400XY + K Groove (Rohm and Haas)
・ Polisher: LGP-612 (LapmaSterSFT)
・ Pressing pressure: 140 hPa
Polishing liquid supply rate: 200 ml / min
Copper blanket wafer: Wafer (φ200 mm) on which a copper film with a thickness of 1.4 μm is formed
Tantalum blanket wafer: Wafer (φ200 mm) on which a tantalum film with a thickness of 1 μm is formed
Pattern wafer: CMP854 pattern wafer (φ200 mm) manufactured by atdf
Polishing pad / wafer rotation speed: 95/120 rpm
-Surface plate temperature control: 20 ° C
・ Temperature when supplying metal polishing liquid: 25 ° C

(Evaluation methods)
(1. Polishing speed)
The average polishing rate was determined by converting the film thickness before and after the CMP of the metal film from the electrical resistance value at 49 locations on the copper blanket wafer surface and 49 locations on the tantalum blanket wafer surface. Further, the obtained polishing rate was introduced into the following formula, and the polishing rate ratio of copper and tantalum (copper / tantalum polishing rate ratio) was calculated.
(Copper / tantalum polishing rate ratio) = (average polishing rate of copper) / (average polishing rate of tantalum)

(2. Dishing)
In addition to the time until the copper in the non-wiring portion is completely polished, the pattern wafer is polished for 30% of the time, and the dishing of the line-and-space portion (line 100 μm, space 100 μm) is touched. Measured with a needle type step gauge.
Table 1 below shows the copper polishing rate, the copper / tantalum polishing rate ratio, and the dishing obtained by CMP using the above polishing liquid.

<Examples 2 to 5>
(B) organic acid, (E) tetrazole derivative or other passive film forming agent used in the composition of the polishing liquid of Example 1, (D) trivalent iron compound (or divalent which is a precursor thereof) The iron compound) was changed to the compounds shown in Table 1 below, and the trivalent iron content contained in the polishing liquid was changed as shown in Table 1 below. 5 was prepared.
Using the obtained polishing liquid, the copper polishing rate, the copper / tantalum polishing rate ratio, and the dishing were determined in the same manner as in Example 1. These results are also shown in Table 1.

<Comparative Examples 1-5>
The (B) organic acid, (E) tetrazole derivative or other passive film forming agent used in the composition of the polishing liquid of Example 1 was changed to the compounds shown in Table 1 below, and (D) a trivalent iron compound. A polishing liquid of Comparative Examples 1 to 5 was prepared in the same manner as in Example 1 except that was not used.
Using the obtained polishing liquid, the copper polishing rate, the copper / tantalum polishing rate ratio, and the dishing were determined in the same manner as in Example 1. These results are also shown in Table 1.

As shown in Table 1, the polishing liquid (Examples 1 to 5) containing the trivalent iron compound in an amount within the range of the present invention was compared with the polishing liquid (Comparative Examples 1 to 5) containing no iron component. It can be seen that the copper polishing rate is excellent and the copper / tantalum polishing rate ratio is excellent.
As is clear from these results, the metal polishing liquid of the present invention has a remarkable effect when applied to polishing of semiconductor devices having a copper film (copper wiring).

Claims (3)

  (A) Chemicals in a wiring process of a semiconductor device, including an oxidizing agent, (B) an organic acid, and (C) abrasive grains, and (D) a trivalent iron compound in a range of 0.1 ppb to 50 ppm. Metal polishing fluid used for mechanical polishing.   The metal polishing slurry according to claim 1, further comprising (E) tetrazole or a derivative thereof.   In a manufacturing process of a semiconductor device, a polishing liquid for metal according to claim 1 or 2 is brought into contact with a surface to be polished of a substrate having a conductor film made of copper or a copper alloy, and the surface to be polished and the polishing pad of the substrate A chemical mechanical polishing method comprising polishing by polishing relative to each other.