JP2008091524A - Polishing liquid for metal - Google Patents

Abstract

（Ｒ^１：水素原子、メチル基、ヒドロキシメチル基、ヒドロキシエチル基、フェニル基、ベンジル基、又はトリフルオロメチル基。Ｒ^２、Ｒ^３：水素原子、アルキル基、アシル基、それぞれが連結して５員または６員環を形成してもよい。但し、Ｒ^２及びＲ^３が共に水素原子になることはない。環を形成する場合は、炭素原子以外の元素を含んでもよい。）
【選択図】なしProvided is a metal-polishing liquid that has a rapid polishing rate, improves flatness, hardly forms a groove between a wiring and an insulating layer, and has high storage stability.
A metal polishing liquid used for chemical mechanical planarization of a semiconductor device, which is composed of at least one polymerizable monomer selected from the group consisting of the following general formula (I): A metal-polishing liquid comprising: a water-soluble polymer that is a polymer containing units; and a silica sol having a volume average particle diameter of secondary particles of 10 to 100 nm and a metal impurity content of 1 ppm or less.

(R ¹ : hydrogen atom, methyl group, hydroxymethyl group, hydroxyethyl group, phenyl group, benzyl group, or trifluoromethyl group. R ² , R ³ : hydrogen atom, alkyl group, acyl group, each linked. A 5-membered or 6-membered ring may be formed, provided that R ² and R ³ are not both hydrogen atoms, and when forming a ring, elements other than carbon atoms may be included.
[Selection figure] None

Description

  The present invention relates to the manufacture of semiconductor devices, in particular, organic materials for polishing metal films, interlayer insulating films, and BPSG films (silicon dioxide films doped with boron and phosphorus) in the wiring process and planarization process of semiconductor devices. The present invention relates to the metal polishing liquid used.

In the development of a semiconductor device typified by a semiconductor integrated circuit (hereinafter referred to as LSI), high density and high integration by miniaturization and lamination of wiring are required for high integration and high speed. As a technique for this, chemical mechanical polishing (Chemical) that polishes an interlayer insulating film (such as SiO ₂ ) or a metal thin film used for wiring, and smoothes the substrate or removes the excess metal thin film during wiring formation. Various techniques such as Mechanical Polishing (hereinafter referred to as CMP) have been used.
A general method of CMP is to apply a polishing pad on a circular polishing platen (platen), immerse the surface of the polishing pad with a polishing liquid, press the surface of the substrate (wafer) against the pad, In a state where pressure (polishing pressure) is applied, both the polishing platen and the base are rotated, and the surface of the base is flattened by the generated mechanical friction.
A polishing solution used for CMP generally contains abrasive grains (for example, alumina, silica) and an oxidizing agent (for example, hydrogen peroxide, persulfuric acid), and oxidizes a metal surface with an oxidizing agent to form an oxide film. It is thought that it is grind | polishing by removing with an abrasive grain.

However, when CMP is performed using a polishing liquid containing such solid abrasive grains, scratches (scratches), a phenomenon in which the entire polished surface is polished more than necessary (thinning), the polished metal surface is not flat, Phenomenon that only the center is polished deeper to produce dish-like depressions (dishing), the insulator between metal wirings is polished more than necessary, and the surface of multiple metal surfaces forms dish-shaped recesses ( Erosion) may occur.
In order to solve such problems in the conventional solid abrasive grains, a 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, , See Patent Document 1). According to this method, although the metal film on the convex portion of the semiconductor substrate is selectively CMPed and the metal film is left in the concave portion to obtain a desired conductor pattern, it is much more mechanical than the conventional solid abrasive grains. Since CMP proceeds by friction with a soft polishing pad, it is difficult to obtain a sufficient polishing rate.

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

Recently, in order to improve productivity, the diameter of a wafer at the time of manufacturing an LSI has been increased. Currently, a diameter of 200 mm or more is widely used, and manufacturing of a diameter of 300 mm or more has started. With such an increase in size, the difference in polishing rate between the wafer center and the periphery has increased, and the demand for improvement in in-plane uniformity has increased.
As a chemical polishing method having no mechanical polishing means for copper and a copper alloy, a chemical polishing method using only a dissolving action is also known (see, for example, Patent Document 2). However, as compared with CMP in which the metal film of the convex portion is selectively chemically and mechanically polished, problems due to the occurrence of dishing and the like are likely to occur, and ensuring flatness is an issue.

In addition, for the purpose of flattening the step of the polishing surface, an aqueous dispersion for chemical mechanical polishing that suppresses deterioration of the polishing pad (for example, see Patent Document 3), iminodiacetic acid useful for correcting the wafer surface, and its A processing fluid containing a chelating agent selected from salts (for example, see Patent Document 4), a chemical mechanical polishing composition containing an α-amino acid (for example, see Patent Document 5), and the like have been proposed. Although these techniques show some improvement in the polishing performance of copper wiring, on the other hand, there is a problem that a groove is generated between the copper wiring and the insulating layer, and it is desired to realize a polishing liquid that does not cause it. This is the current situation.
Further, in the semiconductor manufacturing process, it is important to flatten the interlayer insulating film and the BPSG film. Conventionally, fumed silica-based and cerium oxide-based abrasives have been generally studied as CMP abrasives for planarizing an inorganic insulating film layer such as a silicon oxide insulating film. However, fumed silica and cerium oxide are problematic in that a sufficient polishing rate cannot be obtained and flatness is not sufficient.
JP 2001-127019 A JP 49-122432 A JP 2001-279231 A Special Table 2002-538284 Publication JP 2003-507894 A

  The present invention has been made based on the background that there is a demand for a CMP slurry that realizes faster polishing in order to increase the productivity of LSI. Accordingly, an object of the present invention is to provide a metal-polishing liquid that has a rapid polishing rate, improves flatness, hardly forms a groove between a wiring and an insulating layer, and has high storage stability. .

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

<1> A metal-polishing liquid used for chemical mechanical planarization of semiconductor devices,
A water-soluble polymer which is a polymer containing a repeating unit composed of at least one polymerizable monomer selected from the group consisting of the following general formula (I), and the volume average particle diameter of secondary particles is 10 to 100 nm. And a metal-polishing liquid comprising a silica sol having a metal impurity content of 1 ppm or less.

（一般式（Ｉ）中、Ｒ^１は水素原子、メチル基、ヒドロキシメチル基、ヒドロキシエチル基、フェニル基、ベンジル基、又はトリフルオロメチル基を表す。Ｒ^２及びＲ^３は、それぞれ独立に、水素原子、アルキル基、アシル基を表し、それぞれが連結して５員または６員環を形成してもよい。但し、Ｒ^２及びＲ^３が共に水素原子になることはない。Ｒ^２及びＲ^３が環を形成する場合は、炭素原子以外の元素を含んでもよい。）

(In General Formula (I), R ¹ represents a hydrogen atom, a methyl group, a hydroxymethyl group, a hydroxyethyl group, a phenyl group, a benzyl group, or a trifluoromethyl group. R ² and R ³ are each independently hydrogen atom, an alkyl group, an acyl group, may be respectively to form a 5- or 6-membered ring. However, R ² and R ³ are never both be hydrogen .R ² and R ^{When 3} forms a ring, it may contain an element other than a carbon atom.)

<2> The metal polishing slurry according to <1>, further comprising at least one compound selected from the group consisting of a tetrazole derivative and a triazole derivative.

<3> The metal according to <1> or <2>, further comprising at least one compound selected from the group consisting of compounds represented by the following general formulas (II) and (III): It is a polishing liquid.

（一般式（ＩＩ）中、Ｒ^1aは、単結合、アルキレン基、又はフェニレン基を表す。Ｒ^2a及びＲ^3aは、それぞれ独立に、水素原子、ハロゲン原子、カルボキシル基、アルキル基、シクロアルキル基、アルケニル基、アルキニル基、又はアリール基を表す。Ｒ^4a及びＲ^5aは、それぞれ独立に、水素原子、アルキル基、又はアシル基を表す。但し、Ｒ^1aが単結合のとき、Ｒ^4a及びＲ^5aの少なくともいずれかは水素原子ではない。）

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

（一般式（ＩＩＩ）中、Ｒ^6aは、単結合、アルキレン基、又はフェニレン基を表す。Ｒ^7a及びＲ^8aは、それぞれ独立に、水素原子、ハロゲン原子、カルボキシル基、アルキル基、シクロアルキル基、アルケニル基、アルキニル基、又はアリール基を表す。Ｒ^9aは、水素原子、アシル基又はアルキル基を表す。Ｒ^10aはアルキレン基を表す。但し、Ｒ^10aが−ＣＨ₂−のとき、Ｒ^6aは単結合ではないか、Ｒ^9aが水素原子ではないかの少なくともいずれかである。）

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

<4> The silica sol hydrolyzes and polycondenses tetramethoxysilane by adding an organic solvent containing tetramethoxysilane and a solvent containing an alkali catalyst and water to an organic solvent containing an alkali catalyst and water. The metal polishing slurry according to any one of <1> to <3>, wherein the metal polishing slurry is a manufactured silica sol.

<5> The metal polishing slurry according to any one of <1> to <4>, further comprising cerium oxide or tetravalent hydroxide particles.

<6> The content of the water-soluble polymer is from 0.10 parts by mass to 100 parts by mass with respect to 100 parts by mass of the solid content in the polishing liquid. The metal polishing liquid according to any one of the above.

<7> The metal polishing liquid according to any one of <1> to <6>, wherein the metal polishing liquid is used for polishing copper or tantalum in chemical mechanical planarization of a semiconductor device. A polishing liquid.

  By using the metal polishing liquid of the present invention as a polishing liquid used for chemical mechanical polishing in the manufacture of semiconductor devices, the chemical mechanical polishing rate is improved and the flatness is improved, and the wiring and insulating layer It is possible to fabricate an LSI in which it is difficult to form a groove between the two. Further, the solution before the addition of hydrogen peroxide hardly aggregates and has high storage stability.

  The metal polishing liquid of the present invention is a metal polishing liquid used for chemical mechanical planarization of semiconductor devices, and is at least one polymerizable monomer selected from the group consisting of the following general formula (I) And a water-soluble polymer that is a polymer containing a repeating unit composed of a silica sol having a volume average particle size of secondary particles of 10 to 100 nm and a metal impurity content of 1 ppm or less.

（一般式（Ｉ）中、Ｒ^１は水素原子、メチル基、ヒドロキシメチル基、ヒドロキシエチル基、フェニル基、ベンジル基、又はトリフルオロメチル基を表す。Ｒ^２及びＲ^３は、それぞれ独立に、水素原子、アルキル基、アシル基を表し、それぞれが連結して５員または６員環を形成してもよい。但し、Ｒ^２及びＲ^３が共に水素原子になることはない。Ｒ^２及びＲ^３が環を形成する場合は、炭素原子以外の元素を含んでもよい。）

(In General Formula (I), R ¹ represents a hydrogen atom, a methyl group, a hydroxymethyl group, a hydroxyethyl group, a phenyl group, a benzyl group, or a trifluoromethyl group. R ² and R ³ are each independently hydrogen atom, an alkyl group, an acyl group, may be respectively to form a 5- or 6-membered ring. However, R ² and R ³ are never both be hydrogen .R ² and R ^{When 3} forms a ring, it may contain an element other than a carbon atom.)

[Silica sol]
As the silica sol used in the present invention, a commercially available product may be used as long as it satisfies the above conditions. However, an organic solvent containing tetramethoxysilane and a solution containing an alkali catalyst and water are combined with an alkali catalyst and water. A silica sol obtained by hydrolyzing and polycondensing tetramethoxysilane by adding to the organic solution is more preferable. The organic solvent used is preferably methanol, and the alkali catalyst is preferably ammonia.

The silica fine particles contained in the silica sol used in the present invention are preferably spherical fine particles having a uniform size, and the volume average particle diameter of the secondary particles is 10 to 100 nm. More preferably, it is 20 nm to 50 nm. The volume average particle diameter of the secondary particles is preferably 3 times or less of the average particle diameter of the primary particles, more preferably 1.5 to 3.0 times, and particularly preferably 1.5 to 2.5 times. .
The silica concentration in the silica sol used in the present invention is not particularly limited, but is preferably 10 to 50% by mass.

  The pH of the silica sol used in the present invention is preferably 6.0 to 9.0, and more preferably 7.0 to 8.0.

The metal impurities contained in the silica sol used in the present invention are Al, Ca, B, Ba, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Pb, Sr, Ti, Zn, Zr, U, Th. Etc. The total content of these is 1 ppm or less, preferably 0.1 ppm or less, and more preferably 0.01 ppm or less. When the metal impurity content exceeds 1 ppm, the insulating property of the insulating film is lowered.
Examples of means for setting the metal impurity content to 1 ppm or less include a metal removal method using a chelate resin or an ion exchange resin.
The metal impurity content can be measured by an inductively coupled plasma mass spectrometer (ICP-MS).

R ^{1 in the} general formula (I) represents a hydrogen atom, a methyl group, a hydroxymethyl group, a hydroxyethyl group, a phenyl group, a benzyl group or a trifluoromethyl group, preferably a hydrogen atom or a methyl group, more preferably Is a hydrogen atom.

[Polymerizable monomer represented by formula (I)]
R ² and R ^{3 in} formula (I) each independently represent a hydrogen atom, an alkyl group, or an acyl group, and each may be linked to form a 5-membered or 6-membered ring. However, neither hydrogen atom. When R ² and R ³ form a ring, elements other than carbon atoms may be included. R ² and R ³ are preferably a hydrogen atom or an alkyl group, more preferably an alkyl group, and particularly preferably a linear alkyl group. The preferred alkyl group is an alkyl group of _C 1 _{-C 10,} more preferably an alkyl group of _C 1 -C _3. Particularly preferred is a methyl group.

  Examples of the monomer represented by the general formula (I) include the following compounds. N-methyl acrylamide, N-ethyl acrylamide, N-propyl acrylamide, N-isopropyl acrylamide, N-butyl acrylamide, N-isobutyl acrylamide, Nt-butyl acrylamide, N-heptyl acrylamide, N-octyl acrylamide, N- t-octylacrylamide, N-dodecylacrylamide, N-octadecylacrylamide, N-methylolacrylamide, N-acetylacrylamide, N-diacetoneacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-isopropylmethacrylamide, N-butylmethacrylamide, N-isobutylmethacrylamide, Nt-butylmethacrylamide, N-heptylmethacrylate Amides, N-octylmethacrylamide, Nt-octylmethacrylamide, N-dodecylmethacrylamide, N-octadecylmethacrylamide, N-methylolmethacrylamide, N-acetylmethacrylamide, N-diacetonemethacrylamide, N, N -Dimethylacrylamide, N, N-diethylacrylamide, N, N-dipylacrylamide, N, N-diisopropylacrylamide, N, N-dibutylacrylamide, N, N-diisobutylacrylamide, N, N-di-t-butyl Acrylamide, N, N-diheptylacrylamide, N, N-dioctylacrylamide, N, N-di-t-octylacrylamide, N, N-didodecylacrylamide, N, N-dioctadecylacrylamide, N, N-dimethyl Roll acrylamide, N, N-diacetylacrylamide, N, N-diacetone acrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, N, N-dipylmethacrylamide, N, N-diisopropylmethacrylate Amide, N, N-dibutylmethacrylamide, N, N-diisobutylmethacrylamide, N, N-di-t-butylmethacrylamide, N, N-diheptylmethacrylamide, N, N-dioctylmethacrylamide, N, N -Di-t-octylmethacrylamide, N, N-didodecylmethacrylamide, N, N-dioctadecylmethacrylamide, N, N-dimethylolmethacrylamide, N, N-diacetylmethacrylamide, N, N-didiacetone Methacrylamide, acryloyl pipette Mention may be made of lysine, acryloylmorpholine, acryloylthiomorpholine, acryloylpyrrolidine. These may be used singly or in combination of two or more, as long as the effects of the present invention are not impaired.

  The polymer used for the additive is preferably an N-mono-substituted product of acrylamide, an N-mono-substituted product of methacrylamide, an N-di-substituted product of acrylamide, or an N-di-substituted product of methacrylamide. Is an N-disubstituted acrylamide. Particularly preferred is a polymer of N, N-dimethylacrylamide.

  The amount of the water-soluble polymer added is preferably in the range of 0.01 to 100 parts by mass, more preferably 0.10 to 100 parts by mass with respect to 100 parts by mass of the solid content in the polishing liquid. It is as follows. If the amount added is too small, sufficient flatness cannot be obtained. The weight average molecular weight of the water-soluble polymer is preferably 500 to 5,000,000, and more preferably 1,000 to 1,000,000.

  Further, the water-soluble polymer (polymer) may be a copolymer containing monomer components other than the monomer represented by the general formula (I). Examples of such monomer components include vinyl alcohol, vinyl acetate, acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, acrylonitrile, maleic acid, itaconic acid, vinylamine, vinylpyridine, allylamine, vinylpyrrolidone, vinylcaprolactam, Examples include vinyl methyl ether, vinyl methyl oxazolidinone, vinyl formal, vinyl acetal, vinyl amine, vinyl isobutyl ether, acrylamide, and methacrylamide.

  The water-soluble polymer is obtained by a generally known polymerization method such as radical polymerization. These polymerizations can be carried out by referring to the method described in, for example, the first edition of Experimental Chemistry Course, Volume 18-1, 304, Maruzen, 4th edition, Experimental Chemistry Course, Volume 28, page 151, The Chemical Society of Japan, Maruzen, etc. Can be synthesized.

  The metal polishing slurry of the present invention may contain other water-soluble polymers. Other water-soluble polymers include, for example, polysaccharides (eg, alginic acid, pectic acid, carboxymethylcellulose, agar, xanthan gum, chitosan, methylglycol chitosan, methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, pullulan), poly Carboxylic acid and its derivatives (eg, polyacrylic acid, polymethacrylic acid, polyaspartic acid, polyglutamic acid, polylysine, polymalic acid, polymaleic acid, polyitaconic acid, polyfumaric acid, poly (p-styrene carboxylic acid), polyvinyl sulfate, polyamino Acrylamide, polyamic acid, polyglyoxylic acid), polyethyleneimine, vinyl polymers (eg, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid) Rain), polyglycols (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol) and the like.

  The metal polishing slurry of the present invention contains a water-soluble polymer containing a repeating unit represented by the general formula (I) as a constituent component, a high-purity silica sol, an oxidizing agent, and a solvent / dispersion medium. As long as the effects of the present invention are not impaired, compounds used in known polishing liquids can be selected and used according to the purpose, but as aromatic heterocyclic compounds and oxidation aids It is preferable to contain the organic acid.

The metal polishing slurry of the present invention may further contain other components, and preferred components include, for example, surfactants and various additives. Two or more kinds of each component may be added to the polishing liquid.
The pH of the metal polishing slurry of the present invention is preferably from 3 to 9, and more preferably from 4 to 7.5.
Examples of the medium for the metal polishing slurry of the present invention include water, alcohols (eg, methanol, ethanol, 2-propanol), and ethers (eg, dioxane, tetrahydrofuran), and water is most preferable.

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

  Of the components added when preparing the concentrate of the polishing liquid, the blending amount of water having a solubility in water at room temperature of less than 5% by mass is room temperature in terms of preventing precipitation when the concentrate is cooled to 5 ° C. The solubility in water is preferably within 2 times, more preferably within 1.5 times.

Hereinafter, components that can be used in the metal polishing slurry of the present invention will be described.
〔Oxidant〕
The metal polishing liquid of the present invention contains a compound (oxidant) that can oxidize a 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. Hydrogen peroxide is preferable.

  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.

[Organic acid]
In the polishing liquid of the present invention, an organic acid can be used in combination as an oxidation aid. The organic acid here is a compound having a structure different from that of an oxidizing agent for oxidizing a metal, and does not include an acid that functions as the oxidizing agent.
Examples of the organic acid 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, and 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, Examples thereof include phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, α-amino acids, and ammonium salts and alkali metal salts thereof. In particular, malic acid, tartaric acid, citric acid, glycine, glycolic acid, organic acids represented by the following general formulas (II) and (III), and the like can be mentioned. Preferably, it is a compound (organic acid) represented by the following general formulas (II) and (III).

（一般式（ＩＩ）中、Ｒ^1aは、単結合、アルキレン基、又はフェニレン基を表す。Ｒ^2a及びＲ^3aは、各々独立に、水素原子、ハロゲン原子、カルボキシル基、アルキル基、シクロアルキル基、アルケニル基、アルキニル基、又はアリール基を表す。Ｒ^4a及びＲ^5aは、それぞれ独立に、水素原子、アルキル基、又はアシル基を表す。但し、Ｒ^1aが単結合のとき、Ｒ^4a及びＲ^5aの少なくともいずれかは水素原子ではない。）

(In General Formula (II), R ^1a represents a single bond, an alkylene group, or a phenylene group. R ^2a and R ^3a each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or a cycloalkyl group. , an alkenyl group, .R ^4a and R ^5a represents an alkynyl group, or aryl group, each independently, represent a hydrogen atom, an alkyl group, or an acyl group. provided that when R ^1a is a single bond, R ^4a and R ^At least one of ^5a is not a hydrogen atom.)

（一般式（ＩＩＩ）中、Ｒ^6aは、単結合、アルキレン基、又はフェニレン基を表す。Ｒ^7a及びＲ^8aは、それぞれ独立に、水素原子、ハロゲン原子、カルボキシル基、アルキル基、シクロアルキル基、アルケニル基、アルキニル基、又はアリール基を表す。Ｒ^9aは、水素原子、アシル基又はアルキル基を表す。Ｒ^10aはアルキレン基を表す。但し、Ｒ^10aが−ＣＨ₂−のとき、Ｒ^6aは単結合ではないか、Ｒ^9aが水素原子ではないかの少なくともいずれかである。）

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

The alkylene group as R ^1a in the general formula (II) 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 ^2a and R ^3a preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group. The cycloalkyl group as R ^2a and R ^3a 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 ^2a and R ^3a 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 ^2a and R ^3a 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 ^2a and R ^3a 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 represented by R ^2a and R ^3a 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 ^4a and R ^5a 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 represented by R ^4a and R ^5a may have include a hydroxyl group, an amino group, and a halogen atom.

In general formula (II), it is preferable that either one of R ^4a and R ^5a is not a hydrogen atom.

In general formula (II), it is particularly preferable that R ^1a is a single bond and R ^2a and R ^4a are hydrogen atoms. In this case, R ^3a 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 ^5a 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 ^3a may have, a hydroxyl group, a carboxyl group, or an amino group is preferable. As the substituent that the alkyl group as R ^5a may have, a hydroxyl group or an amino group is preferable.

The alkylene group as R ^6a and R ^{10 a} in the general formula (III) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, such as methylene group, ethylene The 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 ^7a and R ^8a preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and a propyl group. The cycloalkyl group as R ^7a and R ^8a 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 ^7a and R ^8a 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 ^7a and R ^8a 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 ^7a and R ^8a 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 represented by R ^7a and R ^8a 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 ^9a preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group. The acyl group as R ^9a 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 ^9a may have include a hydroxyl group, an amino group, a halogen atom, and a carboxyl group.

In the general formula (III), R ^9a is preferably not a hydrogen atom.

  Although the specific example of a compound represented by general formula (II) or general formula (III) below is given, it is not limited to these.

  The compound represented by the general formula (II) or (III) can be synthesized by a known method, but a commercially available product may be used.

  The addition amount of the organic acid is preferably 0.0005 to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 1 mol in 1 L of the polishing liquid used for polishing. The amount is particularly preferably 0.1 mol. That is, the amount of acid added 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.

[Inorganic acid]
The metal polishing slurry of the present invention can further contain an inorganic acid. The acid here has an action of promoting oxidation, adjusting pH, and buffering agent. Examples of the inorganic acid include sulfuric acid, nitric acid, boric acid, phosphoric acid and the like. Among inorganic acids, nitric acid is preferable.
The addition amount of the acid is preferably 0.0005 to 0.5 mol, more preferably 0.005 mol to 0.3 mol, and more preferably 0.01 mol to 0 mol in 1 L of the polishing liquid used for polishing. .1 mol is particularly preferable. That is, the amount of acid added 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.

[Compound having an aromatic ring]
In the polishing liquid in the present invention, a compound having a function as a passive film forming agent that suppresses deterioration of the oxidant, forms a passive film on the metal surface, and controls the polishing rate, specifically May contain a compound having an aromatic ring.
Preferred are tetrazole and derivatives thereof, 1,3,4-triazole and derivatives thereof, 1,2,4-triazole and derivatives thereof, and benzotriazole and derivatives thereof.
The tetrazole derivative is preferably a tetrazole derivative characterized by containing, as a substituent, one substituted with a carboxyl group or an alkyl group substituted with at least one of a hydroxy group or a carboxy group. More preferably, it is a tetrazole derivative characterized by containing at least one carboxy group. For example, 5-carboxy-1H-tetrazole, 1H-tetrazole-5-acetic acid, 1H-tetrazole-5-propionic acid, 1H-tetrazole-5-succinic acid.

  The 1,2,3-triazole derivative preferably contains a substituent selected from the group consisting of a hydroxy group and a carboxy group, or an alkyl group substituted with at least one of these substituents as a substituent. It is a characteristic 1,2,3-triazole derivative. More preferably, it is a 1,2,3-triazole derivative characterized in that it contains at least one carboxy group or an alkyl group substituted with at least one carboxy group as a substituent. For example, 4-carboxy-1H-1,2,3-triazole, 4,5-dicarboxy-1H-1,2,3-triazole, 1H-1,2,3-triazole-4-acetic acid, 4-carboxy- 5-Carboxymethyl-1H-1,2,3-triazole.

The 1,2,4-triazole derivative is preferably a 1,2,4-triazole derivative containing an alkyl group substituted with a carboxyl group or an alkyl group substituted with at least one of a hydroxy group and a carboxy group as a substituent. 4-triazole derivative. 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-carboxy-1,2,4-triazole, 3,5-dicarboxy-1,2,4-triazole, 1,2,4-triazole-3-acetic acid.
The 1,2,3-benzotriazole derivative preferably contains at least one anionic substituent. More preferably, those having a carboxyl group substituted or those containing an alkyl group substituted with a carboxy group as a substituent.

  These compounds can use a commercial item, and can also synthesize | combine with 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, (1956), Journal of Medicinal Chemistry. 29, 538-549 (1986), Carbohydrate Research, 73, 323-326 (1979). The 1,2,3-triazole derivative can be synthesized with reference to Carbohydrate Research, 38, 107-115 (1974), Journal of Organic Chemistry, 21, 190 (1956). The 1,2,4-triazole derivatives are described in Chemistry of Heterocyclic Compounds, 16, 199 (1979), Chemistry of Heterocyclic Compounds, 5, 121-122 (1969), Journal of Organic Chemistry, 34, 3221, 3227 (1969), It can be synthesized with reference to Journal of Organic Chemistry, 31, 265, 272 (1966).

[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 in 1 L of a metal polishing liquid used for polishing. 0.07 mol is added.

〔Additive〕
Moreover, it is preferable to use the following additives for the metal polishing slurry of the present invention. Ammonia; alkylamines such as dimethylamine, trimethylamine, triethylamine and propylenediamine; amines such as ethylenediaminetetraacetic acid (EDTA), sodium diethyldithiocarbamate and chitosan; dithizone, cuproin (2,2'-biquinoline), neocuproin (2, Imines such as 9-dimethyl-1,10-phenanthroline), bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and cuperazone (biscyclohexanone oxalyl hydrazone); benzimidazole-2-thiol, 2- [2- (benzothiazolyl)] thiopropionic acid, 2- [2- (benzothiazolyl)] thiobutyric acid, 2-mercaptobenzothiazole, 1,2,3-triazole, 1,2,4- Triazole, 3-amino-1H-1,2,4-triazole, benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4- Carboxyl-1H-benzotriazole, 4-methoxycarbonyl-1H-benzotriazole, 4-butoxycarbonyl-1H-benzotriazole, 4-octyloxycarbonyl-1H-benzotriazole, 5-hexylbenzotriazole, N- (1,2 , 3-Benzotriazolyl-1-methyl) -N- (1,2,4-triazolyl-1-methyl) -2-ethylhexylamine, tolyltriazole, naphthotriazole, bis [(1-benzotriazolyl) Chill] azole such as phosphonic acid; nonyl mercaptan, dodecyl mercaptan, triazine thiol, triazine dithiol, mercaptan triazine trithiol etc., other, anthranilic acid, Aminotoruiru acid, quinaldic acid. Among these, chitosan, ethylenediaminetetraacetic acid, L-tryptophan, cuperazone, triazinedithiol, benzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole butyl ester, tolyltriazole, naphthotriazole have high CMP rate and low etching It is preferable for achieving both speeds.

  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 the metal polishing liquid used for polishing. It is especially preferable to set it as 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]
The metal polishing slurry of the present invention preferably contains a surfactant. The surfactant has an action of reducing the contact angle of the surface to be polished and has an action of promoting uniform polishing. As the surfactant and / or hydrophilic polymer to be used, those selected from the following group are suitable.

  Examples of the anionic surfactant include carboxylic acid or a salt thereof, sulfonic acid or a salt thereof, sulfate ester salt, and phosphate ester salt. As the carboxylic acid or salt thereof, soap, N-acylamino acid or a salt thereof, polyoxy Ethylene or polyoxypropylene alkyl ether carboxylic acid or a salt thereof, acylated peptide; sulfonic acid or a salt thereof, alkyl sulfonic acid or a salt thereof, alkylbenzene and alkyl naphthalene sulfonate or a salt thereof, naphthalene sulfonic acid or a salt thereof , Sulfosuccinic acid or a salt thereof, α-olefin sulfonic acid or a salt thereof, N-acyl sulfonic acid or a salt thereof; sulfate ester, sulfated oil, alkyl sulfate, alkyl ether sulfate, polyoxyethylene or polyoxypropylene Alkyl allylate Sulfates, alkylamide sulfates; as phosphoric acid ester salts, alkyl phosphate salts, may be mentioned polyoxyethylene or polyoxypropylene alkyl allyl ether phosphates.

As cationic surfactant, aliphatic amine salt, aliphatic quaternary ammonium salt, benzalkonium chloride salt, benzethonium chloride, pyridinium salt, imidazolinium salt; carboxybetaine type, aminocarboxylate as amphoteric surfactant And imidazolinium betaine, lecithin, and alkylamine oxide.
Nonionic surfactants include ether type, ether ester type, ester type and nitrogen-containing type. Ether type includes polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene 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, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester Le, sucrose esters, nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like. Moreover, a fluorine-type surfactant etc. are mentioned.

  The surfactant is preferably an alkyl benzene sulfonate, and particularly preferably dodecyl benzene sulfonic acid.

  However, when the substrate to be applied is a silicon substrate for a semiconductor integrated circuit or the like, contamination with an alkali metal, an alkaline earth metal, a halide or the like is not desirable, so an acid or an ammonium salt thereof is desirable. This is not the case when the substrate is a glass substrate or the like.

  The total amount of the surfactant added is preferably 0.001 to 10 g, more preferably 0.01 to 5 g in 1 L of the metal polishing liquid used for polishing. It is particularly preferable to set it to ˜3 g. That is, the addition amount of the surfactant is preferably 0.001 g or more in order to obtain a sufficient effect, and is preferably 10 g or less from the viewpoint of preventing the CMP rate from being lowered. Moreover, as a weight average molecular weight of these surfactant, 500-100000 are preferable, and 2000-50000 are especially preferable.

[Alkaline agent and buffer]
The metal-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.

  Alkaline agents and buffering agents include organic ammonium hydroxides such as ammonium hydroxide and tetramethylammonium hydroxide, nonmetallic alkali agents such as alkanolamines such as diethanolamine, triethanolamine, triisopropanolamine, and the like. Alkali metal hydroxides such as sodium, potassium hydroxide and lithium hydroxide, carbonate, phosphate, borate, tetraborate, hydroxybenzoate, glycyl salt, N, N-dimethylglycine salt, leucine Salt, norleucine salt, guanine salt, 3,4-dihydroxyphenylalanine salt, alanine salt, aminobutyrate, 2-amino-2-methyl-1,3-propanediol salt, valine salt, proline salt, trishydroxyaminomethane salt Lysine salts can be used That.

Specific examples of the alkali agent and buffer include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, potassium bicarbonate, trisodium phosphate, tripotassium phosphate, diphosphate phosphate. Sodium, dipotassium phosphate, sodium borate, potassium borate, sodium tetraborate (borax), potassium tetraborate, sodium o-hydroxybenzoate (sodium salicylate), potassium o-hydroxybenzoate, 5-sulfo Examples include sodium 2-hydroxybenzoate (sodium 5-sulfosalicylate), potassium 5-sulfo-2-hydroxybenzoate (potassium 5-sulfosalicylate), ammonium hydroxide, and the like.
Particularly preferred alkali agents are ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethylammonium hydroxide.

The addition amount of the alkaline agent and the buffer may be an amount that maintains the pH within a preferable range, and is preferably 0.0001 mol to 1.0 mol in 1 L of the polishing liquid used for polishing. More preferably, it is 0.003 mol to 0.5 mol.
The pH of the polishing liquid when used for polishing is preferably 2 to 14, more preferably 3 to 12, and most preferably 3.5 to 8. In this range, the metal polishing liquid of the present invention exhibits particularly excellent effects.

  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 and pH.

[Abrasive]
The polishing liquid of the present invention may contain abrasive grains other than high-purity silica sol. Particularly preferred is cerium oxide or tetravalent hydroxide particles. In general, cerium oxide is obtained by oxidizing a cerium compound of carbonate, nitrate, sulfate, or oxalate. Although a manufacturing method is not limited, it is preferable that a cerium oxide crystallite diameter is 5 nm or more and 300 nm or less. Moreover, since it uses for the board | substrate grinding | polishing which concerns on semiconductor manufacture, it is preferable to suppress the content rate of an alkali metal and halogens to 1 ppm or less in a cerium oxide particle. Examples of a method for producing a cerium oxide powder from the cerium compound include baking or an oxidation method using hydrogen peroxide or the like. The firing temperature is preferably 350 ° C. or higher and 900 ° C. or lower, and is preferably used after being mechanically pulverized. As the pulverization method, a dry pulverization method such as a jet mill or a wet pulverization method such as a planetary bead mill is preferable.
As the tetravalent hydroxide particles, rare earth metal hydroxide and zirconium hydroxide are preferable, and cerium hydroxide is particularly preferable. As a method for synthesizing a metal hydroxide, a method described in Chemistry Dojin Co., Ltd., 1999, pp. 304-305, can be used. The specific surface area of the metal hydroxide particles is preferably 100 m ² / g or more, and the average particle diameter of the secondary particles is preferably 300 nm or less.
The addition amount of the abrasive grains is preferably 0.01 to 20% by mass and more preferably 0.05 to 5% by mass with respect to the total mass of the polishing liquid. 0.01% by mass or more is preferable for obtaining a sufficient effect in improving the polishing rate and reducing variation in the polishing rate within the wafer surface, and 20% by mass or less is preferable because the polishing rate by CMP is saturated.

[Raw metal materials]
In the present invention, the semiconductor to be polished is preferably an LSI having wiring made of copper metal and / or copper alloy, and particularly preferably a copper alloy. Furthermore, the copper alloy containing silver is preferable among copper alloys. The silver content contained in the copper alloy is preferably 40% by mass or less, particularly 10% by mass or less, more preferably 1% by mass or less, and most preferably in the range of 0.00001 to 0.1% by mass. Exhibits excellent effects.

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

[Barrier metal]
In the present invention, it is preferable to provide a barrier layer for preventing the diffusion of copper between the wiring in which the semiconductor is made of copper metal and / or a copper alloy and the interlayer insulating film. As the barrier layer, a low-resistance metal material is preferable, and TiN, TiW, Ta, TaN, W, and WN are particularly preferable, and Ta and TaN are particularly preferable.
[Inorganic insulating film]
Examples of the inorganic insulating film polished with the metal polishing liquid of the present invention include silicon oxide and silicon nitride. These films may be formed by any method, and examples thereof include a low pressure CVD method and a plasma CVD method. These films may be doped with an element such as phosphorus or boron.

  The metal polishing slurry of the present invention is preferably used mainly for polishing copper or tantalum in chemical mechanical planarization of semiconductor devices. The water-soluble resin contained in the metal polishing liquid of the present invention functions as a protective film for protecting the surface of copper or the like, and can suppress the generation of grooves between the copper wiring and the insulating layer.

[Polishing method]
The polishing liquid is a concentrated liquid that is diluted by adding water when used, or mixed in the form of an aqueous solution described in the next section for each component, and diluted by adding water as necessary. In some cases, it may be used as a working solution or prepared as a working solution. The polishing method using the metal polishing liquid of the present invention can be applied to any case, and the polishing liquid is supplied to the polishing pad on the polishing surface plate and brought into contact with the surface to be polished to thereby connect the surface to be polished and the polishing pad. This is a polishing method in which polishing is performed by relative movement.
As an apparatus for polishing, there is a general polishing apparatus having a polishing surface plate with a holder for holding a semiconductor substrate having a surface to be polished and a polishing pad attached (a motor etc. capable of changing the number of rotations is attached). Can be used. As the polishing pad, a general nonwoven fabric, foamed polyurethane, porous fluororesin, or the like can be used, and there is no particular limitation. The polishing conditions are not limited, but the rotation speed of the polishing platen is preferably a low rotation of 200 rpm or less so that the substrate does not jump out. The pressure applied to the polishing pad of the semiconductor substrate having the surface to be polished (film to be polished) is preferably ⁵ to 500 g / cm ² in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern. Is more preferably 12 to 240 g / cm ² .

  During polishing, a polishing liquid is continuously supplied to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid. After the polishing, the semiconductor substrate is thoroughly washed in running water, and then dried after removing water droplets adhering to the semiconductor substrate using a spin dryer or the like. In the polishing method of the present invention, the aqueous solution to be diluted is the same as the aqueous solution described below. The aqueous solution is water containing at least one of an oxidizing agent, an acid, an additive, and a surfactant in advance, and the total amount of the components contained in the aqueous solution and the components of the polishing liquid to be diluted is the polishing liquid. Use it as a component when polishing. When diluted with an aqueous solution and used, components that are difficult to dissolve can be blended in the form of an aqueous solution, and a more concentrated polishing liquid can be prepared.

  As a method of diluting by adding water or an aqueous solution to the concentrated polishing 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 a polishing pad to a polishing pad. Mixing is a method in which liquids collide with each other through a narrow passage under pressure, a method in which a filling such as a glass tube is filled in the pipe, and the flow of liquid is repeatedly separated and merged. Conventional methods such as a method of providing blades that rotate in the above can be employed.

  The supply rate of the polishing liquid is preferably 10 to 1000 ml / min, and 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.

  As a method of diluting the concentrated polishing liquid with water or an aqueous solution and polishing, a pipe for supplying the 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. In this method, the polishing pad and the surface to be polished are mixed while being mixed by relative movement. Alternatively, there is a method in which a predetermined amount of concentrated polishing liquid and water or an aqueous solution are mixed in one container, and then the mixed polishing liquid is supplied to a 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 to be supplied to the polishing pad on the polishing platen, In this method, the surface to be polished and the polishing pad are moved relative to each other and brought into contact with the surface to be polished.
For example, an oxidizing agent is one component (A), an acid, an additive, a surfactant, and water are one component (B), and when they are used, the component (A) The component (B) is diluted before use.
In addition, the low-solubility additive is divided into two components (A) and (B), and the oxidizing agent, additive and surfactant are one component (A), and the acid, additive, surfactant and Water is used as one component (B), and when these are used, water or an aqueous solution is added to dilute the component (A) and the component (B). In the case of this example, three pipes for supplying the component (A), the component (B), and water or an aqueous solution are required, and dilution mixing is performed on one pipe that supplies the three pads to the polishing pad. There is a method of combining and mixing in the pipe. In this case, it is also possible to combine two pipes and then connect another pipe.
Here, the specific amino acid derivative according to the present invention is preferably added to (B) together with the passive film-forming agent among the two components from the viewpoint of solution aging stability.

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

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

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

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

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

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

<Examples 1-8, Comparative Examples 1-5>
First, the following components used for each Example and Comparative Example were prepared or synthesized.
・ Preparation of silica sol (silica sol 1)
To 926.2 g of ultrapure water, 209.6 g of 26% ammonia water and 8510 g of methanol were added and stirred well. In this mixed solution, a mixed solution of 6088.8 g of tetramethoxysilane and 458.8 g of methanol, and a mixed solution of 1286.4 g of ultrapure water and 209.6 g of 26% ammonia water were maintained at a liquid temperature of 35 ° C. It was added dropwise over 250 minutes. This silica sol was distilled by heating while adding ultrapure water under normal pressure while maintaining a constant volume, and was terminated when the distillation temperature became 100 ° C. and pH 8 or lower.
The specific surface area of the silica fine particles was measured by the BET method and confirmed to be 166 m ² / g. The primary particle diameter was calculated from 2727 / BET specific surface area and confirmed to be 16.6 nm. The secondary particle size was confirmed to be 29.2 nm by the photon correlation method.

・ Synthesis of water-soluble polymer ~ Synthesis of poly-N, N-dimethylacrylamide ~
200 g of ultrapure water was placed in a 1 liter separate three-necked flask, the temperature was raised to 90 ° C. with stirring in a nitrogen gas atmosphere, and then 100 g of N, N-dimethylacrylamide and 2,2′-azobis {2- A mixture of 1 g of methyl-N- [2- (1-hydroxybutyl)] propionamide} was poured into the flask over 1.5 hours. Thereafter, the mixture was stirred at 90 ° C. for 5 hours and then cooled to room temperature to obtain a water-soluble polymer solution.

~ Synthesis of poly-N-methylacrylamide ~
200 g of ultrapure water was placed in a 1 liter separate three-necked flask, the temperature was raised to 90 ° C. with stirring in a nitrogen gas atmosphere, and 86 g of N-methylacrylamide and 2,2′-azobis {2-methyl- A mixture of 1 g of N- [2- (1-hydroxybutyl)] propionamide} was poured into the flask over 1.5 hours. Thereafter, the mixture was stirred at 90 ° C. for 5 hours and then cooled to room temperature to obtain a water-soluble polymer solution.

Next, metal polishing liquids 1 to 8 of Examples 1 to 8 and metal polishing liquids A-1 to A-5 of Comparative Examples 1 to 5 were prepared according to the formulations shown below. These metal polishing liquids 1 to 8 and metal polishing liquids A-1 to A-5 were evaluated by conducting polishing tests by the following methods.
(Metal polishing liquids 1 to 8, A-1 to A-5)
Hydrogen peroxide (oxidant) 40g / L
Oxidizing adjuvant listed in Table 1 0.2 mol / L
Passive film forming agent described in Table 1 0.003 mol / L
Abrasive grains listed in Table 1 8 ml / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and nitric acid) 7.3

(Polishing test)
Polishing pad: IC1400XY-K Groove (Rodale)
Polishing machine: LGP-612 (LapmaSterSFT)
Holding pressure: 70 g / cm ²
Polishing liquid supply rate: 200 ml / min
Copper blanket wafer: Wafer (200 mm) on which a copper film with a thickness of 1.4 μm is formed
Tantalum blanket wafer: Wafer (200 mm) on which a tantalum film with a thickness of 1 μm is formed
Pattern wafer: CMP854 pattern wafer (200 mm) manufactured by Sematec
Polishing pad / wafer rotation speed: 95/120 rpm
Surface plate temperature control: 20 ° C

[Evaluation methods]
CMP was performed using the metal polishing liquids 1 to 8 and metal polishing liquids A-1 to A-5, and the measurement or evaluation was performed as follows. (1) Polishing rate, (2) Table 1 shows the dishing stability, (3) the depth of the groove between the copper wiring and the insulating layer, and (4) the storage stability at 25 ° C. for 1 month in a polishing solution not containing hydrogen peroxide.
(1) Polishing rate: For 49 locations on the copper or tantalum blanket wafer surface, the film thickness of the metal film before and after CMP was converted from the electrical resistance value to obtain the average polishing rate.
(2) Dishing: In addition to the time until copper of the non-wiring portion is completely polished on the pattern wafer, polishing is performed for a time corresponding to 50% of the time, and the line and space portion (line 100 μm, space 100 μm) ) Was measured with a stylus profilometer.
(3) Groove depth: A cross section was photographed with a scanning electron microscope (SEM), and the depth was measured.
(4) Storage stability: The presence or absence of agglomerates when left in a constant temperature bath at 25 ° C. for one month was visually confirmed.

As shown in Table 1, it can be seen that the metal polishing liquids 1 to 8 of Examples 1 to 8 have a high polishing rate, small dishing, a small groove depth, and excellent storage stability.
On the other hand, the metal polishing liquids A-1 to A-5 of Comparative Examples 1 to 5 can obtain excellent results at the same time for the polishing rate, dishing, groove depth, and storage stability. There wasn't.

<Example 9>
-Preparation of Cerium Oxide Slurry 190 g of cerium carbonate hydrate was placed in a platinum container and baked at 850 ° C for 3 hours to obtain about 90 g of yellowish white cerium oxide powder. Furthermore, 90 g of this cerium oxide powder was pulverized using a jet mill, and it was confirmed that the average primary particle size was 200 nm. However, large pulverized residual particles of 1 to 3 μm were slightly mixed. 90 g of the obtained cerium oxide, 2 g of an aqueous polyacrylic acid ammonium salt solution (40% by mass), and 808 g of deionized water were mixed and stirred for 10 minutes while applying ultrasonic waves. The mixture was filtered through a 1 micron filter, and ultrapure water was added to obtain a 5% by mass cerium oxide slurry.

-Preparation of metal polishing liquid 9 300 g of the above cerium oxide slurry, 150 g of silica sol 1 obtained in Example 1, and 30 g of poly-N, N-dimethylacrylamide solution were added with ultrapure water to a constant volume of 3000 ml. A polishing liquid 9 was obtained.

<Comparative Example 6>
-Preparation of metal polishing liquid A-6 Ultrapure water was added to 600 g of the cerium oxide slurry prepared in Example 6 and 30 g of poly-N, N-dimethylacrylamide solution to make a constant volume of 3000 ml, and metal polishing liquid A- 6 was obtained.

[Insulating film layer polishing]
After forming an Al wiring Line portion having a Line / Space width of 0.05 to 5 mm and a height of 1000 nm on a Si substrate having a diameter of 200 mm, a patterned wafer was prepared in which a silicon oxide film was formed to 2000 nm.
A holder is placed on a polishing surface plate having a diameter of 600 mm to which a polishing pad made of a porous urethane resin is attached, with the insulating film (silicon oxide film) surface of the wafer facing down, and the processing load is 14.7 kPa (150 gf / cm). ² ). While the metal polishing liquid 9 was dropped on the polishing platen at a rate of 300 ml / min, the polishing platen and the wafer were rotated at 50 rpm for 6 minutes to polish the insulating film of the pattern wafer. The polished wafer was thoroughly washed with pure water and then dried.
When the difference in film thickness before and after polishing was measured using an optical interference film thickness measuring apparatus and the polishing rate was calculated, the polishing rate of the Line portion having a Line / Space width of 1 mm was 230 nm / min.
On the other hand, when polishing with the metal polishing liquid A-6, the polishing rate of the Line portion having a Line / Space width of 1 mm was 150 nm / min.
It has been found that the metal polishing slurry of the present invention has a high polishing rate while maintaining flatness even at a low pressure.

Claims (7)

A metal polishing liquid used for chemical mechanical planarization of semiconductor devices,
A water-soluble polymer which is a polymer containing a repeating unit composed of at least one polymerizable monomer selected from the group consisting of the following general formula (I), and the volume average particle diameter of secondary particles is 10 to 100 nm. And a metal sol having a metal impurity content of 1 ppm or less.

(In General Formula (I), R ¹ represents a hydrogen atom, a methyl group, a hydroxymethyl group, a hydroxyethyl group, a phenyl group, a benzyl group, or a trifluoromethyl group. R ² and R ³ are each independently hydrogen atom, an alkyl group, an acyl group, may be respectively to form a 5- or 6-membered ring. However, R ² and R ³ are never both be hydrogen .R ² and R ^{When 3} forms a ring, it may contain an element other than a carbon atom.)   The metal polishing slurry according to claim 1, further comprising at least one compound selected from the group consisting of tetrazole derivatives and triazole derivatives. The metal polishing slurry according to claim 1 or 2, further comprising at least one compound selected from the group consisting of compounds represented by the following general formulas (II) and (III).

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

(In general formula (III), R ^6a represents a single bond, an alkylene group, or a phenylene group. R ^7a and R ^8a are each independently a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or a cycloalkyl group. Represents an alkenyl group, an alkynyl group, or an aryl group, R ^9a represents a hydrogen atom, an acyl group, or an alkyl group, R ^10a represents an alkylene group, provided that when R ^10a is —CH ₂ —, R ^6a Is not a single bond, or R ^9a is not a hydrogen atom.)   The silica sol was prepared by hydrolyzing and polycondensing tetramethoxysilane by adding an organic solvent containing tetramethoxysilane and a solvent containing an alkali catalyst and water to an organic solvent containing an alkali catalyst and water. The metal polishing slurry according to any one of claims 1 to 3, wherein the metal polishing slurry is a silica sol.   The metal polishing slurry according to any one of claims 1 to 4, further comprising cerium oxide or tetravalent hydroxide particles.   The content of the water-soluble polymer is 0.10 parts by mass or more and 500 parts by mass or less based on 100 parts by mass of the solid content in the polishing liquid. The polishing liquid for metal as described.   The metal polishing liquid according to any one of claims 1 to 6, wherein the metal polishing liquid is used for polishing copper or tantalum in chemical mechanical planarization of a semiconductor device.