JP2007220995A - Polishing solution for metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing solution for metal which comprises colloidal silica whose surface is partially covered with aluminum atom as a solid abrasive grain and can restrain residual of the solid abrasive grain on a polishing surface after polishing. <P>SOLUTION: The polishing solution comprises (a) colloidal silica whose surface is partially covered with aluminum atom, (b) organic acid, (c) passive film forming agent, and (d) at least one kind selected from cationic surfactant, nonionic surfactant and water soluble polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a metal polishing liquid, and more particularly to a metal polishing liquid used in a wiring process in semiconductor device manufacturing.

In the development of semiconductor devices represented by semiconductor integrated circuits (hereinafter referred to as “LSI” where appropriate), in recent years, miniaturization and stacking of wiring have led to higher density and higher integration for miniaturization and higher speed. It has been demanded. Various techniques such as chemical mechanical polishing (hereinafter, referred to as “CMP” as appropriate) have been used as techniques for this purpose.
This CMP is an indispensable technique for surface flattening of a film to be processed such as an interlayer insulating film, plug formation, formation of embedded metal wiring, etc., and an extra metal thin film at the time of substrate smoothing or wiring formation It is used for removing (see, for example, Patent Document 1).

  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, and apply a predetermined pressure from the back surface. In the state where (polishing pressure) is applied, both the polishing base plate and the base are rotated, and the surface of the base is flattened by the generated mechanical friction.

  Conventionally, tungsten and aluminum have been widely used in interconnect structures as wiring metals. However, LSIs using copper, which has lower wiring resistance than these metals, have been developed with the aim of achieving higher performance. As a method for wiring this copper, for example, a damascene method is known. Further, a dual damascene method in which a contact hole and a wiring trench are simultaneously formed in an interlayer insulating film and a metal is embedded in both has been widely used. As a target material for this copper wiring, a high purity copper target of five nines or more has been used. However, in recent years, with the miniaturization of wiring aiming at further higher density, it has become necessary to improve the conductivity and electronic characteristics of copper wiring, and accordingly, a copper alloy in which a third component is added to high-purity copper is required. It is also beginning to be considered for use. 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. In the polishing of copper metal, since it is a particularly soft metal, the polishing metal surface is bent on the pan (dishing), the insulation between the metal wiring is polished more than necessary, and multiple wiring metal surfaces The phenomenon of erosion on the plate (erosion) and polishing scratches (scratches) are likely to occur, and a highly accurate polishing technique is increasingly required.

  Furthermore, in recent years, the wafer diameter at the time of manufacturing LSIs has been increased to improve productivity. Currently, the diameter of 200 mm or more is widely used, and the manufacture of 300 mm or more has started. As the size of the wafer increases, the difference in polishing rate between the central portion and the peripheral portion of the wafer tends to occur, and the demand for uniformity of polishing within the wafer surface has become increasingly severe.

  In addition, when copper wiring is used in LSI manufacturing, a diffusion preventing layer called a barrier layer is generally provided between the wiring portion and the insulating layer in order to prevent copper ions from diffusing into the insulating material. The barrier layer is formed of one layer or two or more layers selected from TaN, TaSiN, Ta, TiN, Ti, Nb, W, WN, Co, Zr, ZrN, Ru, and CuTa alloy. This is achieved by the same method as bulk polishing.

  Further, in bulk polishing of copper, dishing is likely to occur particularly in a wide metal wiring portion. Therefore, in order to achieve final planarization, it is desirable to be able to adjust the amount of polishing and removal in the wiring portion and the barrier portion. For this reason, it is desired that the polishing liquid for barrier polishing has an optimum copper / barrier metal polishing selectivity. In addition, since the wiring pitch and wiring density are different in each level of wiring layers, it is further desirable that the polishing selectivity can be adjusted as appropriate.

  The metal polishing liquid used for CMP generally contains solid abrasive grains (for example, alumina and silica) and an oxidizing agent (for example, hydrogen peroxide and persulfuric acid). It is considered that the basic mechanism of CMP using such metal polishing liquid is that the metal surface is oxidized by an oxidizing agent and the oxide film is removed by abrasive grains.

  However, when CMP is performed using a metal polishing liquid containing such solid abrasive grains, polishing scratches, a phenomenon in which the entire polishing surface is polished more than necessary (thinning), and the polishing metal surface on the plate There are cases where a phenomenon of bending (dishing), an insulator between metal wirings is unnecessarily polished, and a phenomenon that a plurality of wiring metal surfaces bend on a plate (erosion).

The use of a metal-polishing liquid containing solid abrasive grains complicates the cleaning process normally performed to remove the polishing liquid remaining on the surface to be polished after polishing. Furthermore, in order to process the liquid after washing (waste liquid), there is a problem in terms of cost, for example, it is necessary to settle and separate solid abrasive grains.
Further, the use of a metal polishing liquid containing solid abrasive grains in CMP has a problem that although a high polishing rate can be obtained, solid abrasive grains agglomerate in the polishing liquid.
U.S. Pat. No. 4,944,836

In order to solve the problems of the metal polishing liquid containing solid abrasive grains as described above, colloidal silica in which a part of the surface is covered with aluminum atoms (hereinafter referred to as “specific colloidal silica” as appropriate). ) Has been investigated as a solid abrasive. The specific colloidal silica has been confirmed to have a negative zeta potential at a pH of 7 or less, and the specific colloidal silica having such characteristics can exist stably without agglomerating with each other in the metal polishing liquid. By including the specific colloidal silica in the metal polishing liquid, an effect excellent in suppressing aggregation of solid abrasive grains is exhibited.
However, on the other hand, copper, which is the main polishing target of CMP, exists in an aqueous solution in the state of Cu ⁺² and is positively charged. Therefore, the specific colloidal silica is easily adsorbed on the copper surface. For this reason, when a metal polishing liquid containing specific colloidal silica is used, a large amount of specific colloidal silica remains on the polished surface after CMP, which may cause defects in the obtained LSI. .
The present invention is made in view of the above problems, and is a metal-polishing liquid containing colloidal silica whose surface is partially covered with aluminum atoms as solid abrasive grains, and is polished after polishing. An object of the present invention is to provide a metal-polishing liquid capable of suppressing the residue of the solid abrasive grains on the surface.

As a result of intensive studies, the present inventors have selected from cationic surfactants, nonionic surfactants, and water-soluble polymers within a range that does not affect the polishing performance together with the specific colloidal silica in the metal polishing liquid. It has been found that the above-mentioned problems can be solved by adding at least one of the above-described compounds, and the present invention has been completed.
That is, the metal polishing liquid of the present invention is as follows.
<1> (a) Colloidal silica whose surface is partially covered with aluminum atoms (specific colloidal silica), (b) an organic acid, (c) a passive film forming agent, and (d) a cationic interface A metal-polishing liquid comprising an activator, a nonionic surfactant, and at least one selected from water-soluble polymers.
<2> The content of at least one selected from (d) a cationic surfactant, a nonionic surfactant, and a water-soluble polymer is 0.0001 with respect to the total mass of the metal polishing slurry. The metal polishing slurry according to <1>, wherein the polishing slurry is in the range of mass% to 1 mass%.

  According to the present invention, there is provided a metal-polishing liquid containing colloidal silica whose surface is partially covered with aluminum atoms as solid abrasive grains, the solid abrasive grains remaining on the surface to be polished after polishing. The metal-polishing liquid which can be suppressed can be provided.

[Metal polishing liquid]
The present invention will be described in detail below.
The metal-polishing liquid of the present invention comprises: (a) colloidal silica (specific colloidal silica) in which at least part of silicon atoms on the surface is replaced with aluminum atoms; (b) an organic acid; and (c) a passive film forming agent. And (d) at least one selected from a cationic surfactant, a nonionic surfactant, and a water-soluble polymer, and in addition, preferably contains an oxidizing agent, etc. It takes the form of a slurry in which the colloidal silica (abrasive grains) is dispersed in an aqueous solution obtained by dissolving each component.

  Moreover, it is preferable that it is 2-7 as pH of the polishing liquid for metals in this invention.

  Each component constituting the metal polishing liquid will be described in detail below, but each component may be used alone or in combination of two or more.

  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 if necessary when used 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 times by volume.

<(A) Colloidal silica in which part of the surface is covered with aluminum atoms>
The metal-polishing liquid of the present invention contains (a) colloidal silica whose surface is partially covered with aluminum atoms (specific colloidal silica) as at least a part of the abrasive grains.

  In the present invention, “a colloidal silica whose surface is partially covered with aluminum” means a state in which aluminum atoms are present on the surface of colloidal silica having a site containing a silicon atom having a coordination number of 4. A colloidal silica surface may be bonded to an aluminum atom coordinated with four oxygen atoms to form a new surface in which the aluminum atom is fixed in a four-coordinate state, and It may be in a state in which silicon atoms existing on the surface are once extracted and a new surface is formed in which aluminum atoms are replaced.

  The colloidal silica used for the preparation of the specific colloidal silica is more preferably a colloidal silica obtained by hydrolysis of alkoxysilane that does not contain impurities such as alkali metals inside the particles. The particle size of the colloidal silica used as a raw material is appropriately selected according to the purpose of use of the abrasive grains, but is generally about 10 to 200 nm.

As a method for obtaining a specific colloidal silica by replacing silicon atoms on the surface of such colloidal silica particles with, for example, a method of adding an aluminate compound such as sodium aluminate to a dispersion of colloidal silica is preferably used. Can do. This method is described in detail in Japanese Patent No. 3463328 and Japanese Patent Application Laid-Open No. 63-123807, and this description can be applied to the present invention.
As another method, a method of adding aluminum alkoxide to a dispersion of colloidal silica can be mentioned.
The aluminum alkoxide used here may be any, but is preferably aluminum isopropoxide, aluminum butoxide, aluminum methoxide, or aluminum ethoxide, and particularly preferably aluminum isopropoxide or aluminum butoxide.

  The specific colloidal silica is acidic in that the aluminosilicate site generated by the reaction between the tetracoordinate aluminate ion and the silanol group on the surface of the colloidal silica fixes a negative charge and gives the particle a large negative zeta potential. Is also excellent in dispersibility. Therefore, it is important that the specific colloidal silica produced by the method as described above exists in a state where an aluminum atom is coordinated to 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 50% or less, and more preferably. Is from 0.01% to 25%, particularly preferably from 0.1% to 10%.
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 colloidal silica surface (number of introduced aluminum atoms / number of surface silicon atom sites) is consumed from the unreacted aluminum compound remaining after the reaction among the aluminum compounds added to the dispersion. The amount of the obtained aluminum compound was calculated, assuming that they reacted 100%, the surface area converted from the colloidal silica diameter, the specific gravity of colloidal silica 2.2, and the number of silanol groups per unit surface area (5-8 pieces / nm ²⁾ it can be estimated from actual measurements obtained specific colloidal silica per se and elemental analysis, aluminum is not present inside the particles, assuming spread uniformly and thinly on the surface, the colloidal silica The surface area / specific gravity and the number of silanol groups per unit surface area are obtained.

As a specific production method, for example, colloidal silica is dispersed in water in the range of 1 to 50% by mass, a pH adjuster is added to the dispersion to adjust the pH to 7 to 11, and then at around room temperature, Add aqueous ammonium aluminate and stir at that temperature for 1-10 hours. Then, the method of removing an impurity by ion exchange, ultrafiltration, etc., and obtaining specific colloidal silica is mentioned.
The size (volume equivalent diameter) of the specific colloidal silica obtained is preferably 3 m to 200 nm, more preferably 5 nm to 100 nm, and particularly preferably 10 nm to 60 nm. In addition, the value measured by the dynamic light scattering method is employ | adopted for the particle size (volume equivalent diameter) of specific colloidal silica.

Among the abrasive grains contained in the polishing composition of the present invention, the mass ratio of the specific colloidal silica is preferably 50% or more, and particularly preferably 80% or more. All of the contained abrasive grains may be a specific colloidal silica.
The content of the specific colloidal silica in the polishing liquid when using the polishing composition is preferably 0.001% by mass to 5% by mass, and more preferably 0.01% by mass to 0.5% by mass. Yes, particularly preferably 0.05% by mass or more and 0.2% by mass or less.

In addition to the specific colloidal silica, the polishing composition of the present invention can contain abrasive grains other than the specific colloidal silica as long as the effects of the present invention are not impaired. As the abrasive grains that can be used here, fumed silica, colloidal silica, ceria, alumina, titania and the like are preferable, and colloidal silica is particularly preferable.
The size of the abrasive grains other than colloidal silica in which at least a part of silicon atoms on the surface are replaced with aluminum atoms is preferably equal to or more than twice that of the specific colloidal silica.

  The polishing composition of the present invention may contain abrasive grains other than the specific colloidal silica. Among all the abrasive grains contained in the metal polishing slurry, the content of the specific colloidal silica is preferably 50% by mass or more, and particularly preferably 80% by mass or more.

  In the polishing composition of the present invention, fumed silica, colloidal silica, ceria, alumina, titania and the like are preferable, and colloidal silica is particularly preferable. These sizes are preferably equal to or more than that of the specific colloidal silica, and are preferably twice or less.

<(B) Organic acid>
The metal polishing slurry of the present invention contains an organic acid. The organic acid here is not a metal oxidizing agent, but has an action of promoting oxidation, adjusting pH, and buffering agent. The organic acid is preferably water-soluble.

As the organic acid, one selected from the following group is more suitable.
That is, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methyl Hexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, apple Acid, tartaric acid, citric acid, lactic acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine, and salts thereof such as ammonium salt and alkali metal salt, sulfuric acid, nitric acid, ammonia, ammonium salts, or a mixture thereof Is mentioned. Among these, oxalic acid, formic acid, malonic acid, malic acid, tartaric acid, citric acid, hydroxyethyliminodiacetic acid, iminodiacetic acid, dihydroxyethylglycine and the like are preferable.
Furthermore, 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-amino Butyric 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 amino acids such as 3-methyl-L-histidine, ergothioneine, L-tryptophan, actinomycin C1, apamin, angiotensin I, angiotensin II, and antipine.

  Among the above organic acids, in particular, malic acid, tartaric acid, citric acid, glycine, glycolic acid, β-alanine, hydroxyethyliminodiacetic acid, iminodiacetic acid, and dihydroxyethylglycine while maintaining a practical CMP rate. It is preferable in that the etching rate can be effectively suppressed.

  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 in terms of the addition amount that ensures a sufficient polishing rate, and is preferably 0.5 mol or less in terms of controlling excessive etching.

  In the metal polishing slurry of the present invention, the organic acid 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.

<(C) Passive film forming agent>
The metal polishing liquid of the present invention contains at least one heterocyclic compound as a compound that forms a passive film on the metal surface to be polished and suppresses a chemical reaction on the substrate.
Here, the “heterocyclic compound” is a compound having a heterocyclic ring containing one or more heteroatoms. A hetero atom means an atom other than a carbon atom or a hydrogen atom. A heterocycle means a cyclic compound having at least one heteroatom. A heteroatom means only those atoms that form part of a heterocyclic ring system, either external to the ring system, separated from the ring system by at least one non-conjugated single bond, Atoms that are part of a further substituent of are not meant.

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

First, the heterocyclic ring that is the mother nucleus is described.
The number of members of the heterocyclic ring of the heterocyclic compound used in the present invention is not particularly limited, and may be a monocyclic compound or a polycyclic compound having a condensed ring. The number of members in the case of a single ring is preferably 3 to 8, more preferably 5 to 7, and particularly preferably 5 and 6. The number of rings in the case of having a condensed ring is preferably 2 to 4, more preferably 2 or 3.
Specific examples of these heterocyclic rings include the following. However, it is not limited to these.

  Pyrrole ring, thiophene ring, furan ring, pyran ring, thiopyran ring, imidazole ring, pyrazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, pyrrolidine ring, Pyrazolidine ring, imidazolidine ring, isoxazolidine ring, isothiazolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, chroman ring, thiochroman ring, isochroman ring, isothiochroman ring, indoline ring, isoindoline ring, pyringin Ring, indolizine ring, indole ring, indazole ring, purine ring, quinolidine ring, isoquinoline ring, quinoline ring, naphthyridine ring, phthalazine ring, quinoxaline ring, quinazoline ring, cinnoline ring, pteridine ring, acridine Perimidine ring, phenanthroline ring, carbazole ring, carboline ring, phenazine ring, anti-lysine ring, thiadiazole ring, oxadiazole ring, triazine ring, triazole ring, tetrazole ring, benzimidazole ring, benzoxazole ring, benzthiazole ring, benz A thiadiazole ring, a benzfuroxan ring, a naphthimidazole ring, a benztriazole ring, a tetraazaindene ring and the like are mentioned, and a triazole ring and a tetrazole ring are more preferred.

Next, substituents that the heterocyclic ring may have will be described.
In the present invention, when a specific moiety is referred to as a “group”, the moiety may be unsubstituted or substituted with one or more (up to the maximum possible) substituents. Means good. For example, “alkyl group” means a substituted or unsubstituted alkyl group. Examples of the substituent that can be used in the heterocyclic compound used in the present invention include the following. However, it is not limited to these.

  Halogen atom (fluorine atom, chlorine atom, bromine atom or iodine atom), alkyl group (straight chain, branched or cyclic alkyl group, and active methine group even if it is a polycyclic alkyl group such as a bicycloalkyl group) ), Alkenyl group, alkynyl group, aryl group, heterocyclic group (regarding the position of substitution), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, heterocyclic oxycarbonyl group, carbamoyl group (substituent) Examples of the carbamoyl group having an N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group), carbazoyl group, carboxy Group or a salt thereof, oxalyl group, oxamoyl group A cyano group, a carbonimidoyl group, a formyl group, a hydroxy group, an alkoxy group (including a group that repeatedly contains an ethyleneoxy group or a propyleneoxy group unit), an aryloxy group, a heterocyclic oxy group, an acyloxy group, (alkoxy or aryloxy) ) Carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (Alkoxy or aryloxy) carbonylamino group, sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylurea Group, N-acylureido group, N-acylsulfamoylamino group, hydroxyamino group, nitro group, quaternized heterocyclic group containing nitrogen atom (for example, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group) , Isocyano group, imino group, mercapto group, (alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, A sulfo group or a salt thereof, a sulfamoyl group (the sulfamoyl group having a substituent is, for example, an N-acylsulfamoyl group or an N-sulfonylsulfamoyl group) or a salt thereof, a phosphino group, a phosphinyl group, or a phosphinyloxy group. Phosphinylamino group, silyl group and the like.

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

  Among these, preferable substituents include, for example, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, or iodine atoms), alkyl groups (straight chain, branched or cyclic alkyl groups, and polycyclic groups such as bicycloalkyl groups). An alkyl group or an active methine group), an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group (regarding the position of substitution), an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, hetero Ring oxycarbonyl group, carbamoyl group, N-hydroxycarbamoyl group, N-acylcarbamoyl group, N-sulfonylcarbamoyl group, N-carbamoylcarbamoyl group, thiocarbamoyl group, N-sulfamoylcarbamoyl group, carbazoyl group, oxalyl group, Oxamoyl group, cyano group, carbonimido Group, formyl group, hydroxy group, alkoxy group (including groups containing ethyleneoxy group or propyleneoxy group unit), aryloxy group, heterocyclic oxy group, acyloxy group, (alkoxy or aryloxy) carbonyloxy group, carbamoyl Oxy group, sulfonyloxy group, (alkyl, aryl, or heterocyclic) amino group, acylamino group, sulfonamide group, ureido group, thioureido group, N-hydroxyureido group, imide group, (alkoxy or aryloxy) carbonylamino group , Sulfamoylamino group, semicarbazide group, thiosemicarbazide group, hydrazino group, ammonio group, oxamoylamino group, N- (alkyl or aryl) sulfonylureido group, N-acylureido group, N-acyl Sulfamoylamino group, hydroxyamino group, nitro group, heterocyclic group containing a quaternized nitrogen atom (eg, pyridinio group, imidazolio group, quinolinio group, isoquinolinio group), isocyano group, imino group, mercapto group, ( Alkyl, aryl, or heterocyclic) thio group, (alkyl, aryl, or heterocyclic) dithio group, (alkyl or aryl) sulfonyl group, (alkyl or aryl) sulfinyl group, sulfo group or a salt thereof, sulfamoyl group, N- Examples include acylsulfamoyl group, N-sulfonylsulfamoyl group or a salt thereof, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl group and the like. Here, the active methine group means a methine group substituted with two electron-withdrawing groups, and the electron-withdrawing group here means an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkyl group. Examples include a sulfonyl group, an arylsulfonyl group, a sulfamoyl group, a trifluoromethyl group, a cyano group, a nitro group, and a carbonimidoyl group.

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

  Two of the above substituents can be combined to form a ring (aromatic or non-aromatic hydrocarbon ring or heterocyclic ring. These can be further combined to form a polycyclic fused ring. For example, a benzene ring. , Naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring, biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine Ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine Ring, phenanthroline ring Thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, a phenothiazine ring and a phenazine ring.) May also be formed.

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

  The heterocyclic compounds used in the present invention may be used alone or in combination of two or more. Moreover, the heterocyclic compound used by this invention can be synthesize | combined according to a conventional method, and may use a commercial item.

  The total amount of the heterocyclic compound used in the present invention is 0. In 1 L of a metal polishing liquid used for polishing (that is, a metal polishing liquid after dilution when diluted with water or an aqueous solution). 0001-1.0 mol is preferable, More preferably, it is 0.0005-0.5 mol, More preferably, it is 0.0005-0.05 mol.

<(D) Cationic surfactant, nonionic surfactant, and water-soluble polymer>
The metal polishing slurry of the present invention contains at least one selected from a cationic surfactant, a nonionic surfactant, and a water-soluble polymer. (D) It is preferable that content of a component is the range of 0.0001 mass%-1 mass% with respect to the total mass of the polishing liquid for metals.

-Cationic surfactant-
As the cationic surfactant, aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium chloride salts, benzethonium chloride, pyridinium salts, and imidazolinium salts are preferable. Among these, aliphatic amine salts, aliphatic More preferred are quaternary ammonium salts and benzalkonium chloride salts.
The total amount of the cationic surfactant added is preferably 0.0001 to 10 g and more preferably 0.01 to 5 g in 1 L of a metal polishing liquid used for polishing. 0.1-3 g is particularly preferable.

-Nonionic surfactant-
Nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene poly Examples include oxypropylene block polymer, polyoxyethylene polyoxypropylene alkyl ether, ether ester type, glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, sorbitol ester polyoxyethylene ether, ester type, Polyethylene glycol fatty acid ester, glycerol ester, polyglycerol ester, sorbitan ester, propylene glycol ester Ether, sucrose ester, a nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like.

  The total amount of the nonionic surfactant added is preferably 0.0001 to 10 g, more preferably 0.01 to 5 g in 1 liter of the metal polishing liquid used for polishing. 0.1-3 g is particularly preferable.

-Water-soluble polymer-
Examples of water-soluble polymers include polyacrylic acid and salts thereof, polymethacrylic acid and salts thereof, polyamic acid and salts thereof, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrenecarboxylic acid), and polyglyoxylic acid. And polycarboxylic acids thereof and salts thereof. Furthermore, vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrolein can be mentioned.

  However, if the object to be polished is a silicon substrate for a semiconductor integrated circuit or the like, contamination with alkali metal, alkaline earth metal, halide, etc. is not desirable, so if the water-soluble polymer is an acid, use it as an acid. Or the ammonium salt is preferably used. Among the above, as the water-soluble polymer, polyacrylic acid ammonium salt, polyvinyl alcohol, polo vinyl pyrrolidone, polyethylene glycol, and polyoxyethylene polyoxypropylene block polymer are more preferable.

  The total amount of the water-soluble polymer added is preferably 0.0001 to 30 g, more preferably 0.01 to 10 g in 1 L of a metal polishing liquid used for polishing. It is especially preferable to set it as 1-3g.

The addition amount of the surfactant and / or water-soluble polymer as component (d) according to the present invention is preferably 0.001 g or more in 1 liter of the metal polishing liquid in order to obtain a sufficient effect. 10 g or less is preferable from the viewpoint of preventing the decrease in the thickness.
Moreover, as a weight average molecular weight of these surfactant and / or water-soluble polymer, 50-100000 are preferable, and 200-50000 are especially preferable.
Only one type of surfactant according to the present invention may be used, two or more types may be used, and different types of surfactants may be used in combination.

  The content ratio of the component (d) according to the present invention to the specific colloidal silica as the component (a) is preferably 0.0001: 1 to 1: 0.001 in terms of mass ratio. The ratio is more preferably 001: 1 to 1: 0.01, and particularly preferably 0.005: 1 to 1: 0.1.

  In addition, the metal-polishing liquid of this invention may contain other surfactants other than the surfactant which concerns on this invention in the range which does not impair the effect of this invention.

<(E) Oxidizing agent>
The polishing liquid of the present invention preferably contains a compound (oxidant) that can oxidize the metal to be polished.
Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, chlorate, perchlorate, persulfate, Examples thereof include dichromate, permanganate, ozone water, silver (II) salt, and iron (III) salt.
Examples of iron (III) salts include inorganic iron (III) salts such as iron nitrate (III), iron chloride (III), iron sulfate (III), iron bromide (III), and organic iron (III) salts. 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, thiol Glycolic acid, ethylenediamine, trimethylenediamine, diethylene glycol, triethylene glycol, 1,2-ethanedithiol, malonic acid, glutaric acid, 3-hydroxybutyric acid, propionic acid, phthalic acid, isophthalic acid, 3-hydroxysalicylic acid, 3,5 -In addition to dihydroxysalicylic acid, gallic acid, benzoic acid, maleic acid and the like and salts thereof, aminopolycarboxylic acids and salts thereof may be mentioned.

  Aminopolycarboxylic acids and salts thereof include ethylenediamine-N, N, N ′, N′-tetraacetic acid, 1,3-diaminopropane-N, N, N ′, N′-tetraacetic acid, ethylenediamine-N, N '-Disuccinic acid (racemic), ethylenediamine disuccinic acid (SS), N- (2-carboxylateethyl) -L-aspartic acid, N- (carboxymethyl) -L-aspartic acid, β-alanine diacetic acid, Examples thereof include methyliminodiacetic acid, nitrilotriacetic acid, iminodiacetic acid, and salts thereof. The type of counter salt is preferably an ammonium salt.

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

  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 per 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.

  Moreover, it is preferable to mix and use an oxidizing agent in the composition containing other components other than an oxidizing agent, when grind | polishing using polishing liquid. The timing for 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.

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

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

<(G) pH adjuster>
The metal polishing slurry of the present invention may contain an inorganic acid, an alkali agent, and further a buffer from the viewpoint of suppressing pH fluctuations, as necessary, for pH adjustment. Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid, and carbonic acid. Among inorganic acids, nitric acid and phosphoric acid are preferable.
Alkaline agents and buffering agents include organic ammonium hydroxides such as ammonia, ammonium hydroxide and tetramethylammonium hydroxide, non-metallic alkaline agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, carbonates such as sodium carbonate, phosphates such as trisodium phosphate, borate, tetraborate, hydroxybenzoate, etc. Can be mentioned.
Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

The addition amount of the pH adjuster may be an amount that allows the pH to be maintained in a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the metal polishing liquid used for polishing. More preferably, the amount is 0.003 mol to 0.5 mol.
By using the acid, alkali agent and buffer, the pH of the metal polishing slurry of the present invention is adjusted to the above preferred range.

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

  In the present invention, depending on 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 to set the amount, pH, and dispersion medium.

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

[Chemical mechanical polishing method]
A chemical mechanical polishing method to which the metal polishing liquid of the present invention is suitably applied is to supply the metal polishing liquid of the present invention to a polishing pad on a polishing surface plate, and rotate the polishing surface plate. The polishing is performed by moving the polishing pad relative to the surface to be polished while being in contact with the surface to be polished.
Hereinafter, this chemical mechanical polishing method will be described in detail.

(Polishing equipment)
An apparatus capable of carrying out a polishing method to which the metal polishing liquid of the present invention is applied will be described.
As a polishing apparatus, a holder for holding an object to be polished (semiconductor substrate or the like) having a surface to be polished, and a polishing platen to which a polishing pad is attached (a motor or the like whose rotation speed can be changed is attached), A general polishing apparatus provided can be used. For example, FREX300 (Ebara Manufacturing Co., Ltd.) can be used.

(Polishing pressure)
In the polishing method to which the present invention is applied, polishing is preferably performed at a polishing pressure, that is, a contact pressure between the surface to be polished and the polishing pad of 3000 to 250,000 Pa, and more preferably 6500 to 14000 Pa.

(Number of rotations of polishing surface plate)
In the polishing method to which the present invention is applied, polishing is preferably performed at a rotation speed of the polishing platen of 50 to 200 rpm, and more preferably 60 to 150 rpm.

(Polishing liquid supply method)
The polishing liquid is supplied by continuously supplying the metal polishing liquid to the polishing pad on the polishing surface plate with a pump or the like while polishing the target metal. 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.

  In the polishing method to which the present invention is applied, water or an aqueous solution can be added to a concentrated polishing liquid for dilution. As a dilution method, for example, a method of supplying a concentrated polishing liquid to a polishing pad by joining and mixing a pipe for supplying a concentrated polishing liquid and a pipe for supplying water or an aqueous solution together in the middle. Can be mentioned. In this case, mixing is a method in which liquids collide with each other through a narrow passage with pressure applied, a method in which a filling such as a glass tube is filled in the piping, a flow of liquid is separated and separated, and piping is repeated. Conventional methods such as a method of providing blades that rotate with power can be used.

Further, as another dilution method, a pipe for supplying a 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 to the polishing pad, and the polishing pad and the surface to be polished are provided. A method of mixing by relative motion can also be used in the present invention.
Further, it is also possible to apply a method in which a predetermined amount of concentrated polishing liquid and water or an aqueous solution are mixed in one container, mixed and diluted to a predetermined concentration, and then the mixed liquid is supplied to the polishing pad.

  In addition to these methods, a method in which the component to be contained in the polishing liquid is divided into at least two components, and when these are used, water or an aqueous solution is added and diluted to be supplied to the polishing pad is also used in the present invention. be able to. In this case, it is preferable to divide and supply a component containing an oxidizing agent and another component such as an organic acid in the present invention.

  Specifically, an oxidizing agent is one component (A), and an organic acid, a non-conductive film forming agent, a surfactant and / or a water-soluble polymer, an additive, and water are one component (B). It is preferable to dilute the component (A) and the component (B) with water or an aqueous solution when using them. In this case, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are necessary, and the three pipes are connected to one pipe for supplying the polishing pad, The two pipes may be combined and then another one pipe may be combined and mixed. For example, 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 polishing liquid is supplied by combining a pipe of water or an aqueous solution. It is also possible.

  Further, the above three pipes may be led to the polishing pad and mixed and supplied by the relative movement of the polishing pad and the surface to be polished. After mixing the three components in one container, the mixed solution is supplied. You may supply to a polishing pad. Further, the metal polishing liquid may be a concentrated liquid, and the diluted water may be separately supplied to the polishing surface.

(Abrasive supply amount)
In the polishing method to which the metal polishing liquid of the present invention is applied, the supply amount of the polishing liquid onto the polishing surface plate is preferably 50 to 500 ml / min, and more preferably 100 to 300 ml / min.

(Polishing pad)
There is no restriction | limiting in particular as a polishing pad, A non-foaming structure pad or a foaming structure pad may be sufficient. 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.

  The polishing pad in the present invention may further 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.

  Next, an object to be polished (substrate, wafer) to be polished using the metal polishing liquid of the present invention will be described.

The object to be polished in the present invention is preferably a substrate (wafer) having wiring made of copper or a copper alloy.
The diameter of the wafer is preferably 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.

(Wiring metal material)
As the wiring metal material, a copper alloy containing silver is suitable among the copper alloys. The silver content contained in the copper alloy exhibits an excellent effect at 10% by mass or less, further 1% by mass or less, and the most excellent effect in the copper alloy in the range of 0.00001 to 0.1% by mass. Demonstrate.

(Wiring thickness)
In the DRAM device system, for example, the object to be polished in the present invention preferably has a wiring with a half pitch, preferably 0.15 μm or less, more preferably 0.10 μm or less, and further preferably 0.08 μm or less.
On the other hand, the MPU device system preferably has a wiring of preferably 0.12 μm or less, more preferably 0.09 μm or less, and still more preferably 0.07 μm or less.
The polishing liquid used in the present invention exhibits a particularly excellent effect on the object to be polished having such wiring.

(Barrier metal material)
In the object to be polished in the present invention, a barrier layer for preventing copper diffusion is provided between the copper wiring and the insulating film (including the interlayer insulating film). As the barrier metal material constituting the barrier layer, a low-resistance metal material such as TiN, TiW, Ta, TaN, W, or WN is preferable, and Ta or TaN is particularly preferable.

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

[Preparation of specific colloidal silica (A-1)]
Ammonia water is added to 1000 g of a 20 mass% aqueous dispersion of colloidal silica to adjust the pH to 9.0, and then the Al ₂ O ₃ concentration is 3.6% by weight and Na ₂ O / Al with stirring at room temperature. 15.9 g of an aqueous sodium aluminate solution having a ₂ O ₃ molar ratio of 1.50 was slowly added within a few minutes and stirred for 0.5 hours. The obtained sol was placed in a SUS autoclave, heated at 130 ° C. for 4 hours, and then filled with a hydrogen-type strongly acidic cation exchange resin (Amberlite IR-120B), and a hydroxyl group-type strongly basic anion exchange. A column packed with a resin (Amberlite IRA-410) was passed through the column at a space velocity of 1 h ⁻¹ at room temperature, and the initial distillation was cut.

[Preparation of specific colloidal silica (A-2)]
In the preparation of the specific colloidal silica (A-1), a column filled with a hydrogen-type strongly acidic cation exchange resin (Amberlite IR-120B) without performing heat treatment, and a hydroxyl group-type strongly basic anion exchange resin ( A column packed with Amberlite IRA-410) was passed through a column at a space velocity of 1 h ^-1 at room temperature, and the initial distillation was cut.

  The obtained specific colloidal silicas A-1 to A-2 did not show thickening or gelation after preparation.

The surface atom substitution rate (number of introduced aluminum atoms / number of surface silicon atom sites) of the specific colloidal silica thus obtained was determined as follows.
First, of the sodium aluminate added to the dispersion, the amount of sodium aluminate consumed from the unreacted sodium aluminate remaining after the reaction was calculated. Assuming that 100% of the consumed sodium aluminate has reacted, from the surface area converted from the colloidal silica diameter, the specific gravity of the colloidal silica of 2.2, and the number of silanol groups per unit surface area (5 to 8 / nm ² ) The surface atom substitution rate was estimated. The aluminum coating amount of the specific colloidal silica obtained by the above method was 1%. Moreover, the size (volume equivalent diameter) of specific colloidal silica was 30 nm when measured by the above-mentioned method.

<Examples 1 to 9, Comparative Example 1>
(Preparation of metal polishing liquid)
Using the specific colloidal silica obtained as described above as abrasive grains, metal polishing liquids (1) to (12) of Examples and Comparative Examples were prepared with the compositions shown below.

-Composition of metal polishing liquid-
・ (A) Specific colloidal silica (average particle size 30 nm) 5 g / L
・ (B) Organic acid: Glycine ... 10g / L
(C) Passive film forming agent: benzotriazole (BTA) 1 g / L
(D) Surfactant or water-soluble polymer shown in Table 1 (amount described in Table 1)
(E) Oxidizing agent: 30% hydrogen peroxide ... 15 g / L
Pure water was added to make a total volume of 1000 mL, and the pH was adjusted to 4.5 using nitric acid and ammonia. Note that (e) the oxidizing agent was added to the polishing liquid immediately before polishing.

  Using each metal polishing liquid obtained as described above, polishing was performed by the following polishing method.

(Polishing method: Polishing using 8-inch wafer)
The apparatus “LGP-613” manufactured by Lapmaster Co. was used as a polishing apparatus, and the copper film provided on each wafer was polished under the following conditions while supplying the polishing liquid.
Object to be polished (base): Silicon wafer with 8 inch copper film Table rotation speed: 50 rpm
Head rotation speed: 50 rpm
Polishing pressure: 168 hPa
Polishing pad: Product number IC-1400 manufactured by Rodel Nitta Co., Ltd.
Polishing liquid supply speed: 200 ml / min

(Evaluation)
(1) Evaluation of Residual Abrasive Grains on Polished Surface after Polishing After each wafer after polishing was sufficiently washed with water and dried, using a scanning electron microscope “S-4800” manufactured by Hitachi High-Technology Corporation. The wafer surface state was observed, and the abrasive grains remaining on the wafer surface were confirmed. The evaluation criteria are as follows. The results are shown in Table 1.
-Evaluation criteria-
○: No abrasive grains (less than 10 per square centimeter)
(Triangle | delta): The state by which an abrasive grain is confirmed (about 10 or more per square centimeter and less than about 1000 pieces)
X: A state in which abrasive grains are confirmed on one surface (about 1000 or more per square centimeter)

(2) Evaluation of Precipitation / Aggregation Generation after Time of Metal Polishing Liquid After each metal polishing liquid was allowed to stand for 24 hours, the presence / absence of precipitation / aggregation in the polishing liquid was visually confirmed. The evaluation criteria are as follows. The results are shown in Table 1 -Evaluation criteria-
○: Precipitation is not visually confirmed ×: Precipitation is visually confirmed

  As shown in Table 1, (a) component (d) (cationic surfactant, nonionic surfactant, and water-soluble polymer) according to the present invention is contained in a metal polishing liquid containing specific colloidal silica. It was confirmed that in the metal polishing liquid of the example to which at least one selected from (1) was added, residual abrasive grains on the surface to be polished after polishing were suppressed. In addition, the amount of component (d) added is within the range of 0.0001% by mass to 1% by mass from the viewpoint of suppressing residual abrasive grains on the surface to be polished and the dispersion stability of the abrasive grains in the polishing liquid. It has been confirmed that it is particularly suitable.

Claims (2)

(A) colloidal silica in which part of the surface is covered with aluminum atoms;
(B) an organic acid;
(C) a passive film-forming agent;
(D) at least one selected from a cationic surfactant, a nonionic surfactant, and a water-soluble polymer;
A metal-polishing liquid, comprising:   The content of at least one selected from (d) a cationic surfactant, a nonionic surfactant, and a water-soluble polymer is 0.0001% by mass to the total mass of the metal polishing slurry. The metal polishing slurry according to claim 1, wherein the metal polishing slurry is in the range of 1% by mass.