JP2008227098A - Polishing liquid for metal - Google Patents

Abstract

Disclosed is a metal polishing liquid for chemical mechanical polishing that has a rapid polishing rate, improves flatness, and hardly forms a groove between a wiring and an insulating layer.
The present invention relates to a metal-polishing liquid used for chemical mechanical polishing of semiconductor devices, a silica sol, an aromatic compound having at least one of a sulfo group or a carboxyl group as a substituent, or a salt thereof. And a formalin condensate.
[Selection figure] None

Description

  The present invention relates to a metal-polishing liquid used in the manufacture of semiconductor devices, and more particularly to 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. ) For a metal-mechanical polishing liquid used for chemical mechanical polishing.

In the development of semiconductor devices typified by semiconductor integrated circuits (hereinafter sometimes referred to as “LSI”), in order to increase the integration and speed of semiconductor devices, wiring miniaturization and lamination methods are studied. Has been.
As a technique for this purpose, various techniques such as chemical mechanical polishing (hereinafter sometimes referred to as “CMP”) are employed. CMP is used to polish an interlayer insulating film (such as SiO ₂ ) and a metal thin film used for wiring to smooth the substrate or remove an excess metal thin film at the time of wiring formation.

A general method of CMP is as follows.
A polishing pad is affixed on a circular polishing platen (platen), and the surface of the polishing pad is immersed in a polishing liquid. The surface of the substrate (wafer) is pressed against the polishing pad, and both the polishing surface plate and the substrate are rotated with a predetermined pressure (polishing pressure) applied from the back surface.
In CMP, the surface of the substrate is flattened by mechanical friction generated by the above operation.

  Generally, a polishing solution used for CMP includes abrasive grains (for example, alumina and silica) and an oxidizing agent (for example, hydrogen peroxide and persulfuric acid). It is considered that this oxidant oxidizes the surface of the metal that is the object to be polished to form an oxide film, and the abrasive grains remove the oxide film to polish the metal surface.

  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, the metal film on the convex portion of the semiconductor substrate is selectively chemically and mechanically polished to leave the metal film on the concave portion, so that a desired semiconductor pattern can be obtained. However, since this polishing liquid performs polishing with a polishing liquid that does not contain solid abrasive grains and a soft polishing pad, the polishing speed is slower than conventional polishing liquids that are mechanically polished by the friction of solid abrasive grains. Improvements that speed up the process are desired.

  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. In addition, with the miniaturization of wiring for higher density, it is necessary to improve the electrical conductivity and resistance to electronic migration of copper wiring. Along with this, copper containing a small amount of a third component such as silver added to high-purity copper The use of alloys is also being 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.

  In recent years, wafers have become larger in order to improve productivity. Currently, wafers with a diameter of 200 mm or more are widely used, and the manufacture of wafers with a diameter 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 increase, and there is a strong demand for uniform polishing within the wafer surface.

On the other hand, as a chemical polishing method in which mechanical polishing means is not applied to copper and a copper alloy, a chemical polishing method using only a dissolving action is also disclosed (for example, see Patent Document 2).
However, in the chemical polishing method, problems such as dishing are likely to occur and flatness is a problem as compared with CMP in which the metal film of the convex portion is selectively chemically and mechanically polished.

In addition, for the purpose of leveling the polishing surface, an aqueous dispersion for chemical mechanical polishing that suppresses deterioration of the polishing pad (see, for example, 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.
These technologies are improving the polishing performance of copper wiring, but on the other hand, there is a problem that a groove is formed between the copper wiring and the insulating layer, and it is possible to realize a polishing liquid that can solve this new problem. It is desired.

Further, in the semiconductor device manufacturing process, it is also important to flatten the interlayer insulating film and the BPSG film (silicon dioxide film doped with boron (B) and phosphorus (P)). Conventionally, fumed silica-based and cerium oxide-based abrasives have been studied as CMP abrasives used for planarizing an inorganic insulating film layer such as a silicon oxide insulating film.
However, in the fumed silica system and cerium oxide, the polishing rate and flatness are not sufficient, and further improvement is desired.
JP 2001-127019 A JP 49-122432 A JP 2001-279231 A Special Table 2002-538284 Publication JP 2003-507894 A

  It is an object of the present invention to provide a metal polishing liquid for chemical mechanical polishing that has a rapid polishing rate, improves flatness, and hardly forms a groove between a wiring and an insulating layer. .

  As a result of intensive studies on the problems related to the above-mentioned metal-polishing liquid for chemical mechanical polishing, the present inventors have found that the problems can be solved by using the following polishing liquid, and have completed the present invention. The present invention is as follows.

<1> silica sol and an aromatic compound having at least one of a sulfo group or a carboxyl group as a substituent, or a formalin condensate of these salts,
A metal polishing liquid used for chemical mechanical polishing of semiconductor devices.

<2> The metal polishing slurry according to <1>, which is mainly used for polishing copper or tantalum of the semiconductor device.

<3> The metal polishing slurry according to <1> or <2>, wherein the content of the formalin condensate is 1 × 10 ^{−5 to} 0.1% by mass.

<4> The metal for any one of <1> to <3>, wherein the formalin condensate is contained at 0.001 to 10% by mass with respect to the silica sol. A polishing liquid.

<5> Any one of the above <1> to <4>, wherein the formalin condensate is an ammonium salt or an acid obtained by ion exchange of a sodium salt of an aromatic sulfonic acid formalin condensate. The metal polishing liquid according to Item.

<6> The metal polishing slurry according to any one of <1> to <5>, further comprising an anionic surfactant other than the formalin condensate.

<7> The metal polishing slurry according to any one of <1> to <6>, further comprising at least one α-amino acid.

<8> Furthermore, any one of said <1>-<7> characterized by including at least 1 sort (s) of compounds chosen from the group which consists of a compound denoted by the following general formula (I) or (II). The metal polishing liquid according to Item.

In general formula (I), 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, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ^4a and R ^5a each independently represents a hydrogen atom, an alkyl group, or an acyl group. However, when R ^1a is a single bond, R ^4a and R ^5a are not simultaneously hydrogen atoms.

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

<9> The metal polishing slurry according to any one of <1> to <8>, further comprising at least one tetrazole derivative.

<10> The metal polishing slurry according to any one of <1> to <9>, further comprising at least one of 1,2,3-triazole derivatives.

  According to the present invention, it is possible to provide a metal polishing liquid for chemical mechanical polishing that has a rapid polishing rate, improves flatness, and hardly forms a groove between a wiring and an insulating layer.

<Metal polishing liquid for chemical mechanical polishing>
The metal-polishing liquid for chemical-mechanical polishing of the present invention (hereinafter sometimes referred to as “CMP polishing liquid”) is a metal-polishing liquid used for chemical-mechanical polishing of semiconductor devices. And an aromatic compound having at least one of a sulfo group or a carboxyl group as a substituent or a formalin condensate of these salts (hereinafter sometimes referred to as “anionic formalin condensate”).

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 addition, among the components added when preparing the concentrate of the metal polishing liquid, the blending amount of water having a solubility in water at room temperature of less than 5% by mass is to prevent precipitation when the concentrate is cooled to 5 ° C. The solubility in water at room temperature is preferably within 2 times, more preferably within 1.5 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 physical concentration operations such as evaporation are performed. It is used in a different way from the meaning of the general terms involved.

The CMP polishing liquid of the present invention preferably contains an anionic formalin condensate and silica sol as constituent components, and further contains an oxidizing agent and a solvent / dispersion medium. Furthermore, as long as the effect of the present invention is not impaired, a compound used in a known polishing liquid can be selected and used according to the purpose, and an aromatic heterocyclic compound and an organic acid as an oxidation auxiliary agent can be used. It is preferable to contain.
The CMP polishing liquid 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.
Hereinafter, the components of the metal polishing slurry of the present invention will be described.

[Anionic formalin condensate]
The CMP polishing liquid of the present invention contains an aromatic compound having at least one of a sulfo group or a carboxyl group as a substituent or a formalin condensate (anionic formalin condensate) of these salts.
Although the CMP polishing liquid containing the anionic formalin condensate has a rapid polishing rate, the flatness is improved, and it is not clear why it is difficult to form a groove between the wiring and the insulating layer. It is presumed that the copper and / or tantalum surface adsorbed with an appropriate strength to prevent copper oxidation and dissolution. However, the present invention is not limited by such estimation.

The number of sulfo groups is preferably 1 to 2 and more preferably 1 in one aromatic ring. The substitution position of the sulfo group may be any.
The number of carboxyl groups is preferably 1 to 2 and more preferably 1 in one aromatic ring. Any substitution position of the carboxyl group may be used.
As a substituent of the aromatic ring of the anionic formalin condensate, a sulfo group and a carboxyl group may coexist, but it is preferable to have at least a sulfo group or a sulfonate group.

  The aromatic ring of the anionic formalin condensate may be an aromatic hydrocarbon ring or an aromatic hetero ring, but an aromatic hydrocarbon ring is preferred, and a benzene ring, a naphthalene ring, an anthracene ring And more preferably a benzene ring or a naphthalene ring.

  When the aromatic ring is a naphthalene ring, the crosslinking site by formalin may be in the α-position or β-position. When the aromatic ring is a benzene ring, the cross-linking site by formalin is preferably α-position with respect to the hydroxyl group.

The sulfo group and / or carboxyl group in the anionic formalin condensate may be in any state of a salt and an acid. When the anionic formalin condensate is a salt, it is preferably a sodium salt, ammonium salt, potassium salt, triethanolamine salt, diethanolamine salt, ethanolamine salt, tetramethylammonium salt, etc., sodium salt, ammonium salt More preferred are salts and potassium salts, and even more preferred are ammonium salts.
An anionic formalin condensate which is an ammonium salt can be synthesized by converting the sodium salt into an acid by ion exchange and neutralizing with ammonia water.

  When the sulfo group and / or the carboxyl group in the anionic formalin condensate is a salt, any method may be used to convert it into an acid, and for example, an ion exchange method can be applied.

  In particular, the anionic formalin condensate is preferably an acid or an ammonium salt, and most preferably an ammonium salt.

  Examples of the anionic formalin condensate include the following sodium salt compounds. It is not limited to these. Moreover, it does not necessarily need to be a single component of these structures.

  Specific examples in the case where the anionic formalin condensate is an ammonium salt include those obtained by converting the sodium salt mentioned as the above specific example into an acid by ion exchange and neutralizing with ammonia water.

  Specific examples of the case where the anionic formalin condensate is an acid include those obtained by converting the sodium salt mentioned as the above specific example into an acid by ion exchange.

Examples of the anionic formalin condensate include compounds having the following carboxyl groups. It is not limited to these. Moreover, it does not necessarily need to be a single component of these structures.

A commercial item can be used for the anionic formalin condensate used by this invention. Examples of the anionic formalin are commercially available as naphthalenesulfonic acid formalin condensate sodium salt and special aromatic sulfonic acid formalin condensate sodium salt. Specifically, for example, DEMOL N, NL, RN, RN-L, T-45, MS, SN-B, SS-L, SC-30, BASF TAMOLE (Tamol, registered trademark) manufactured by Kao Corporation Series.

The addition amount of the anionic formalin condensate is preferably 1 × 10 ^{−5 to} 0.1% by mass in the polishing liquid when used for polishing, more preferably 1 × 10 ^{−4 to} 0.05. It is mass%, More preferably, it is 1 * 10 < ^-4 > -0.01 mass%.

The addition amount of the anionic formalin condensate is preferably 0.001 to 10% by mass, more preferably 0.01 to 5% by mass, and 0.01 to 1% by mass with respect to the silica sol described later. % Is more preferable.
The addition amount of the anionic formalin condensate is preferably 1 × 10 ^{−5 to} 100% by mass, more preferably 1 × 10 ⁻⁴ to 10% by mass with respect to the oxidizing agent. It is further more preferable that it is * 10 < ^-3 > ^-1 mass%.

[Silica sol]
The metal polishing slurry of the present invention contains at least one silica sol as abrasive grains.
The silica sol may be a commercially available product, but a mixed solution containing tetramethoxysilane and an organic solvent and a mixed solution containing an alkali catalyst and water are mixed into a mixed solution containing an alkali catalyst, water, and an organic solvent. A silica sol produced by adding and hydrolyzing and polycondensing tetramethoxysilane is more preferable. The organic solvent used is preferably methanol, and the alkali catalyst is preferably ammonia.

  The silica particles contained in the silica sol are preferably spherical particles having a uniform size, and the average secondary particle size is preferably 10 to 100 nm, more preferably 20 to 50 nm. Moreover, it is preferable that the average particle diameter of a secondary particle is 3 times or less of the average particle diameter of a primary particle, 1.5-3.0 times are more preferable, and 1.5-2.5 times are especially preferable.

  Although the silica density | concentration in the silica sol used by this invention is not specifically limited, It is preferable that it is 10-50 mass%, and it is more preferable that it is 15-30 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 metal impurities is preferably 1 ppm or less, more preferably 0.1 ppm or less, and further preferably 0.01 ppm or less from the viewpoint of maintaining the insulating properties of the insulating film. preferable.

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).

  From the viewpoint of obtaining a sufficient polishing rate, the total amount of silica sol described above is preferably 0.01% by mass to 10% by mass in terms of solid content in a metal polishing liquid used for polishing. 0.05 mass% to 1 mass% is more preferable.

  The polishing liquid of the present invention may contain abrasive grains other than the silica sol. Preferably, those described in paragraph No. [0042] on page 12 of JP-A No. 2006-261333 can be used. The preferable addition amount is also the same.

〔Oxidant〕
In the present invention, the oxidizing agent refers to a compound capable of oxidizing a metal to be polished. Examples of the oxidizing agent include hydrogen peroxide, peroxide, nitrate, iodate, periodate, hypochlorite, chlorite, persulfate, ozone water and silver (II) salt, An iron (III) salt is mentioned. Hydrogen peroxide is preferable.

  The oxidizing agent is preferably used by mixing with a composition containing other components other than the oxidizing agent when polishing using a polishing liquid. The timing of mixing the oxidizing agent is preferably within 1 hour immediately before using the polishing liquid, more preferably within 5 minutes, and particularly preferably, a mixer is provided immediately before the polishing liquid is supplied by the polishing apparatus. This is the case of mixing within 5 seconds immediately before being supplied to the polishing surface.

  In addition, since the CMP polishing liquid of this invention contains the said anionic formalin condensate, the solution before adding an oxidizing agent is hard to aggregate and is excellent in storage stability.

  The amount of the oxidizing agent added is preferably 0.003 mol or more in 1 L of the metal polishing liquid from the viewpoint of sufficient metal oxidation and ensuring a high CMP rate, and preferably 8 mol or less from the viewpoint of preventing roughening of the polished surface. 0.03 mol to 6 mol is more preferable, and 0.1 mol to 4 mol is particularly preferable.

[Organic acid]
An organic acid can be used in combination with the metal polishing slurry of the present invention. 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 include phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, and α-amino acid. In particular, malic acid, tartaric acid, citric acid, glycine, glycolic acid, α-amino acids, organic acids represented by the following general formulas (I) and (II), and the like, more preferably general formulas (I) and ( It is an organic acid represented by II).

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

The alkylene group as R ^1a in the general formula (I) 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 in formula (I) 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 in formula (I) 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 in formula (I) 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 in the general formula (I) 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 in the general formula (I) preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group. The alkylene chain in these groups may have a hetero atom such as an oxygen atom or a sulfur atom.
Examples of the substituent that each group as R ^2a and R ^3a in the general formula (I) may have include a hydroxyl group, a halogen atom, an aromatic ring (preferably having 3 to 15 carbon atoms), a carboxyl group, an amino group, and the like. Can be mentioned.

The alkyl group as R ^4a and R ^5a in formula (I) 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 in formula (I) may have include a hydroxyl group, an amino group, and a halogen atom.

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

In general formula (I), 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 in formula (I) represents a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, or an acyl group, more preferably an alkyl group, and still more preferably an alkyl group having a hydroxyl group or an amino group as a substituent.
As the substituent that the alkyl group as R ^3a in formula (I) may have, a hydroxyl group, a carboxyl group, or an amino group is preferable.

In general formula (II), R ^6a represents a single bond, an alkylene group, or a phenylene group.
R ^7a and R ^8a in the general formula (II) each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group.
R ^9a in the general formula (II) represents a hydrogen atom, a halogen atom, a carboxyl group, or an alkyl group.
R ^10a in the general formula (II) represents an alkylene group.
However, 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 ^6a and R ^10a in the general formula (II) may be linear, branched or cyclic, and preferably has 1 to 8 carbon atoms, such as a methylene group or an ethylene group. Can be mentioned. Examples of the substituent that the alkylene group and the phenylene group may have include a hydroxyl group and a halogen atom.

The alkyl group as R ^7a and R ^8a in the general formula (II) 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 in the general formula (II) 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 in the general formula (II) 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 in the general formula (II) 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 in the general formula (II) preferably has 6 to 15 carbon atoms, and examples thereof include a phenyl group.

The alkylene chain in these groups represented by R _7a and R _8a 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 in the general formula (II) preferably has 1 to 8 carbon atoms, and examples thereof include a methyl group and an ethyl group.
The acyl group as R ^9a in the general formula (II) 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 general formula (II), R ^9a is preferably not a hydrogen atom, more preferably an alkyl group, and further preferably an unsubstituted alkyl group or an alkyl group having a hydroxyl group or a carboxyl group as a substituent.

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

  The compound represented by the general formula (I) or (II) 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 in 1 L of a polishing liquid used for polishing from the viewpoint of suppressing the etching and exhibiting the effect of adding the organic acid. It is more preferable to set it to 0.005 mol-0.3 mol, and it is especially preferable to set it as 0.01 mol-0.1 mol.

[Inorganic acid]
The polishing liquid 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 in 1 L of the polishing liquid used for polishing from the viewpoint of suppressing the etching and exhibiting the effect of adding the inorganic acid. It is more preferable to set it as 005 mol-0.3 mol, and it is especially preferable to set it as 0.01 mol-0.1 mol.

[Heteroaromatic ring compound]
The metal polishing liquid according to the present invention includes 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 heteroaromatic ring compound. The heterocyclic compound described in JP-A-2006-261333, page 4, paragraph [0016] can be used.

Preferred heteroaromatic ring compounds are those having 3 or more nitrogen atoms in the molecule and a condensed ring structure, and heteroaromatic ring compounds having 4 or more nitrogen atoms in the molecule As mentioned. Furthermore, the heteroaromatic ring compound preferably contains a carboxyl group, a sulfo group, a hydroxy group, or an alkoxy group.
Specifically, as the heteroaromatic ring compound in the present invention, tetrazole and derivatives thereof, 1,2,3-triazole and derivatives thereof, 1,3,4-triazole and derivatives thereof, and benzotriazole and derivatives thereof are preferable.

The tetrazole derivative is preferably a tetrazole derivative containing an alkyl group substituted with at least one of a carboxyl group, an amino group, a hydroxy group or a carboxy group as a substituent. More preferably, it is a tetrazole derivative containing at least one carboxy group or amino group.
For example, 5-carboxy-1H-tetrazole, 1H-tetrazole-5-acetic acid, 1H-tetrazole-5-propionic acid, 5-amino-1H-tetrazole and the like can be mentioned.

Preferably, the 1,2,3-triazole derivative contains a substituent selected from the group consisting of a hydroxy group, a carboxy group or an amino group, or an alkyl group substituted with at least one of these substituents. 1,2,3-triazole derivatives. More preferably, it is a 1,2,3-triazole derivative containing at least one hydroxy group or an alkyl group substituted with at least one hydroxy group as a substituent.
For example, 4-hydroxy-1H-1,2,3-triazole, 4-hydroxymethyl-1H-1,2,3-triazole, 4-1H-1,2,3-triazole.

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

These compounds can also use a commercial item, and can also synthesize | combine with reference to the following literatures.
Tetrazole derivatives are described in Chemische Berichte, 34, 3120 (1901), Chemische Berichte, 89, 2648, (1956), Chemische Berichte, 89, 2652, (1956), Journal of Medicinal Chemistry, 29, 538-549 (1986), Carbohydrate Research, 73, 323-326 (1979), 1,2,3-triazole derivatives are Carbohydrate Research, 38,107-115 (1974), Journal of Organic Chemistry, 21,190 (1956), 1,2,4-triazole derivatives Chemistry of Heterocyclic Compounds, 16, 199 (1979), Chemistry of Heterocyclic Compounds, 5, 121-122 (1969), Journal of Organic Chemistry, 34, 3221, 3227 (1969), Journal of Organic Chemistry, 31, 265 , 272 (1966).

  The total amount of the heterocyclic compound added in the present invention is preferably in the range of 0.001 to 1% by mass, more preferably 0.005 to 0% with respect to the polishing liquid used for polishing. .1% by mass, and more preferably 0.005 to 0.05% by mass.

[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 Zyl) ethylenediamine-N, N′-diacetic acid, 1,2-dihydroxybenzene-4,6-disulfonic acid and the like.

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.

[Surfactant]
The metal polishing slurry of the present invention may be used in combination with 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 carboxylate, sulfonate, sulfate ester salt and phosphate ester salt. As the carboxylate salt, soap, N-acyl amino acid salt, polyoxyethylene or polyoxypropylene alkyl ether carboxyl Acid salt, acylated peptide; as sulfonate, alkyl sulfonate, alkyl benzene and alkyl naphthalene sulfonate, naphthalene sulfonate, sulfosuccinate, α-olefin sulfonate, N-acyl sulfonate; sulfate ester Salts include sulfated oil, alkyl sulfates, alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates; phosphate ester salts such as alkyl phosphates, polyoxyethylene or polyoxy B pyrene alkyl allyl ether phosphate can be exemplified.

Nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type.
Examples of ether type nonionic surfactants include polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene polyoxypropylene block polymer, and polyoxyethylene polyoxypropylene alkyl ether.
Examples of ether ester type nonionic surfactants include glycerin ester polyoxyethylene ether, sorbitan ester polyoxyethylene ether, and sorbitol ester polyoxyethylene ether.
Examples of the ester type nonionic surfactant include polyethylene glycol fatty acid ester, glycerin ester, polyglycerin ester, sorbitan ester, propylene glycol ester, and sucrose ester.
Examples of the nitrogen-containing nonionic surfactant include fatty acid alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamide and the like.
Moreover, a fluorine-type surfactant etc. are mentioned.

  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.

[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. As the alkali agent and buffer, those described in paragraph No. [0049] on page 14 of JP-A No. 2006-261333 can be used. The preferable addition amount is also the same.

〔solvent〕
Examples of the solvent for the CMP polishing liquid of the present invention include water, alcohols (for example, methanol, ethanol, 2-propanol and the like), and ethers (for example, dioxane and tetrahydrofuran), and water is most preferable.

[PH of polishing liquid for metal]
The pH of the polishing liquid of the present invention is preferably 3 or more and 9 or less, and more preferably 4 or more and 7.5 or less. When the metal polishing liquid is a concentrated liquid and is diluted with water or a solvent when used, the above pH range indicates a value after dilution with water or a solvent.

<Polishing method, preparation method of metal polishing liquid, etc.>
The metal polishing liquid is a concentrated liquid, and when used, it is diluted with water or a solvent to prepare a working liquid, or each component is mixed in the form of an aqueous solution described in the next section. May be diluted to give a working solution or may be prepared as a working solution. The polishing method using the polishing liquid of the present invention can be applied to any case, supplying the polishing liquid to the polishing pad on the polishing surface plate, and bringing the polishing surface and the polishing pad into relative motion by bringing them into contact with the surface to be polished. This is a polishing method for polishing.

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 10 to 600 hPa, and in order to satisfy the uniformity of the polishing rate within the wafer surface and the flatness of the pattern, More preferably, it is 20-250 hPa.

  During polishing, a polishing liquid is continuously supplied to the polishing pad with a pump or the like. Although there is no restriction | limiting in this supply amount, it is preferable that the surface of a polishing pad is always covered with polishing liquid. The semiconductor substrate after polishing 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.
As a mixing method, a method of colliding and mixing liquids through a narrow passage with pressure applied, a method of repeatedly filling a pipe such as a glass tube with a filling such as a glass tube, and separating and separating the flow of liquid, A commonly used method such as a method of providing blades rotating with power can be employed.

  The supply rate of the metal 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.

According to another polishing method of the present invention, the component to be contained in the polishing liquid is divided into at least two components, and when these components are used, they are diluted by adding water or an aqueous solution and 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 in the metal polishing slurry.

  A raw material in which other components not containing an oxidizing agent are heated and dissolved in the range of room temperature to 100 ° C. is precipitated in the solution when the temperature is lowered. It is necessary to dissolve what is deposited by heating. For this, a means for feeding a heated component solution and a means for stirring the liquid containing the precipitate, feeding the liquid, and heating and dissolving the 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 the 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.

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

[Wiring thickness]
In the present invention, the semiconductor to be polished is, for example, an LSI having a wiring with a half pitch of 0.15 μm or less, more preferably 0.10 μm or less, and further 0.08 μm or less in a DRAM device system. Is preferred.
On the other hand, in the MPU device system, it is preferably 0.12 μm or less, more preferably 0.09 μm or less, and further preferably an LSI having a wiring of 0.07 μm or less. 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]
The inorganic insulating film polished with the polishing liquid of the present invention is used as the aforementioned interlayer insulating film, and examples thereof 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.

[Polishing pad]
As the polishing pad, the one described in paragraph [0067] on page 16 of JP-A No. 2006-261333 can be used.

[Wafer]
The target wafer to be subjected to CMP with the metal polishing liquid of the present invention preferably has a diameter of 200 mm or more, 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.

[Example 1]
A metal polishing liquid 1 having the following formulation was prepared. This metal polishing liquid was evaluated by conducting a polishing test by the following method.

(Metal polishing liquid 1)
Hydrogen peroxide (oxidant) 18.0g / L
Glycine 15.0g / L
Benzotriazole 0.050 g / L
Demall SS-L (manufactured by Kao Corporation) 0.030g / L
Colloidal silica (abrasive) 0.5g / L
Add pure water, total volume 1000mL
pH (adjusted with ammonia water and nitric acid) 7.5

(Polishing test)
Polishing pad: Rohm and Haas, part number IC-1400,
(K-grv) + (A21)
Polishing machine: LGP-612 (LapmaSterSFT)
Holding pressure: 140 hPa
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 on which a tantalum film with a thickness of 1 μm is formed (200 mm)
Pattern wafer: CMP854 pattern wafer (200 mm) manufactured by Sematec
Table rotation speed: 64 rpm
Head rotation speed: 65rpm
Surface plate temperature control: 20 ° C

(Evaluation methods)
-Polishing speed of copper blanket wafer-
For 49 locations on the copper blanket wafer surface, the thickness of the metal film before and after CMP was converted from the electrical resistance value, and the average polishing rate was determined. The results are shown in Table 1.

-Dishing-
In addition to the time until the copper in the non-wiring portion is completely polished, the pattern wafer is polished for a time corresponding to 50% of the time, and dishing of the line and space portion (line 100 μm, space 100 μm) is performed. Measured with a stylus profilometer.
It means that flatness is excellent, so that the obtained value is small.

−Groove depth between copper wiring and insulation layer−
The pattern wafer was polished by the polishing method in the dishing evaluation, and the cross section of the wafer was observed with an electron microscope (SEM). This is shown in FIG. Table 1 shows the result of measuring the depth of the groove formed between the tantalum provided between the insulating layer and the insulating layer and the copper wiring.

[Examples 2 to 8]
In the formulation of the metal polishing slurry 1 in Example 1, the glycine was changed to the organic acid (0.1 mol / L) and the anionic formalin condensate (0.030 g / L) shown in Table 1, respectively. The polishing liquids of Examples 2 to 8 were prepared in the same manner as in Example 1, and the polishing test was conducted in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Examples 1-3]
The polishing liquids of Comparative Examples 1 to 3 were prepared in the same manner as in Example 1 except that glycine was changed to the organic acids (0.1 mol / L) shown in Table 1 and the anionic formalin condensate was not added. A polishing test was conducted in the same manner as in Example 1. The results are shown in Table 1.

  As shown in Table 1, the metal polishing liquid containing the anionic formalin condensate according to the present invention is a polishing liquid containing an amino acid having a high polishing rate such as glycine, A-4, and A-5. Thus, it has been clarified that the effect of improving the dishing and improving the groove formed between the copper wiring and the insulating layer is excellent without significantly reducing the polishing rate.

In an Example, it is sectional drawing of the sample for evaluating the depth of the groove | channel between a copper wiring and an insulating layer.

Claims (10)

Silica sol and an aromatic compound having at least one of a sulfo group or a carboxyl group as a substituent or a formalin condensate of these salts,
Metal polishing liquid used for chemical mechanical polishing of semiconductor devices.   The metal-polishing liquid according to claim 1, wherein the metal-polishing liquid is mainly used for polishing copper or tantalum of the semiconductor device. The metal polishing slurry according to claim 1, wherein the content of the formalin condensate is 1 × 10 ^{−5 to} 0.1 mass%.   The metal polishing slurry according to any one of claims 1 to 3, wherein the formalin condensate is contained in an amount of 0.001 to 10 mass% with respect to the silica sol.   The said formalin condensate is what carried out the ion exchange of the sodium salt of aromatic sulfonic-acid formalin condensate, and was made into the ammonium salt or the acid, The any one of Claims 1-4 characterized by the above-mentioned. Metal polishing liquid.   Furthermore, an anionic surfactant other than the said formalin condensate is contained, The metal polishing liquid of any one of Claims 1-5 characterized by the above-mentioned.   Furthermore, at least 1 sort (s) of alpha-amino acid is contained, The metal polishing liquid of any one of Claims 1-6 characterized by the above-mentioned. Furthermore, at least 1 sort (s) of compounds chosen from the group which consists of a compound denoted by the following general formula (I) or (II) is included, The statement of any 1 paragraph of Claims 1-7 characterized by things. Metal polishing liquid.

[In General Formula (I), 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, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ^4a and R ^5a each independently represents a hydrogen atom, an alkyl group, or an acyl group. However, when R ^1a is a single bond, R ^4a and R ^5a are not simultaneously hydrogen atoms. ]

[In General Formula (II), R ^6a represents a single bond, an alkylene group, or a phenylene group. R ^7a and R ^8a each independently represent a hydrogen atom, a halogen atom, a carboxyl group, an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, or an aryl group. R ^9a represents a hydrogen atom, an alkyl group, or an acyl group. R ^10a represents an alkylene group. However, when R ^10a is —CH ₂ —, R ^6a is not a single bond and R ^9a is not a combination of hydrogen atoms. ]   The metal polishing slurry according to claim 1, further comprising at least one tetrazole derivative.   The metal polishing slurry according to any one of claims 1 to 9, further comprising at least one of 1,2,3-triazole derivatives.

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