JP2009218473A - Cleaning agent and method of washing semiconductor device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning agent that can effectively remove organic substance smearing and particle smearing existing on the surface of a semiconductor device, especially on the surface with copper wiring provided thereon without causing corrosion of the copper wiring, and to provide a method of washing using the agent. <P>SOLUTION: The cleaning agent is used after a chemical-mechanical polishing process of the semiconductor device having the copper wiring on the surface in a semiconductor device manufacturing process, and contains at least one of amino polycarboxylic acids selected from general formulas (I) to (IV). Also, a method of washing using the agent is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cleaning agent used for cleaning a semiconductor device after a planarization process by chemical mechanical polishing (hereinafter referred to as “CMP”) in a manufacturing process of a semiconductor device, and a semiconductor device using the same. This relates to the cleaning method.

In the manufacturing process of semiconductor devices such as microprocessors, memories, and CCDs, and flat panel display devices such as TFT liquid crystals, patterns with a fine dimension of about 10 to 100 nm are formed on the surface of a substrate such as silicon, silicon oxide (SiO ₂ ), or glass. Formation of thin films and thin film formation are being performed, and it is an extremely important issue to reduce a small amount of contamination on the surface of the substrate in each manufacturing process. Among contaminations on the substrate surface, particle contamination, organic contamination, and metal contamination reduce the electrical characteristics and yield of the device, so it is necessary to reduce them as much as possible before bringing them into the next process. In order to remove such contamination, the substrate surface is generally cleaned with a cleaning liquid. For this cleaning, it is required to clean a highly clean surface at a low cost in a short time with good reproducibility without any side effects. This required level is becoming stricter with the recent high integration and low cost of devices.

  In the manufacture of a semiconductor device typified by a semiconductor integrated circuit (hereinafter referred to as LSI), a multilayer stacked structure in which layers such as insulating films and metal films are stacked on a substrate is formed. In recent years, in order to increase the speed and integration of devices, a new metal material (Cu or the like) having a low resistance value as a wiring and a low dielectric constant (Low-k) material as an interlayer insulating film, that is, a relative dielectric constant of 3. Interlayer insulating film including a low dielectric constant interlayer film of about 5 to 2.0 (for example, organic polymer-based, methyl group-containing silica-based, H-Si-containing silica-based, SiOF-based, porous silica-based, porous organic-based, etc.) After depositing a metal film such as (ILD film) or copper used for wiring, a process of flattening the generated irregularities by CMP and stacking new wiring on the flattened surface is generally performed. . Conventionally, RCA cleaning in which an acidic or alkaline solution and hydrogen peroxide are mixed has been used for cleaning between processes. However, according to these cleaning agents, the passivation that has adhered to the insulating film and should be removed is used. In addition to copper oxide, the metal copper of the wiring is dissolved, which may cause corrosion and disconnection of the wiring. Also, many of the low dielectric constant insulating films have a hydrophobic surface and thus repel the cleaning liquid, making it difficult to clean. Further, in the cleaning after the CMP process, there is a problem that the slurry (abrasive particles) used in the CMP remains on the surface of the wiring and the low dielectric constant insulating film and is contaminated.

In order to remove particles adhering to and remaining on the surface of the semiconductor device after the polishing process, an alkaline cleaning agent in which the semiconductor surface and the particles are electrostatically repelled is generally effective. A cleaning agent containing an agent and an alkali or organic acid has been proposed (see, for example, Patent Document 1).
In addition, it is considered effective to use a component having a plurality of carboxyl groups in order to prevent corrosion and oxidation of the surface of a semiconductor device provided with copper wiring. For example, an organic acid or organic alkali having one or more carboxyl groups is used. A cleaning agent to which a surfactant is added (for example, see Patent Document 2) has been proposed.
However, these cleaning agents still have room for improvement from the viewpoint of efficiently removing metals, substrate materials, organic residues and abrasive fine particles resulting from the object to be polished attached to the substrate surface. .
In particular, there is a need for a cleaning agent that can effectively remove impurities on the surface of a hydrophobic low dielectric constant insulating film or a semiconductor device with copper wiring while suppressing corrosion and oxidation of the copper wiring. This is the current situation.
JP 2003-289060 A JP-A-2005-260213

  An object of the present invention made in consideration of the above problems is a cleaning agent used in a cleaning process after a planarization polishing process in a semiconductor device manufacturing process, in which a copper wiring is applied to the surface of a semiconductor device, in particular, the surface. Another object of the present invention is to provide a cleaning agent that can effectively remove organic contamination and particle contamination present on the surface of a semiconductor device without causing corrosion of copper wiring, and a cleaning method for a semiconductor device using the same.

As a result of earnestly examining the problems relating to the cleaning agent used after the CMP process, the present inventor found that the problem can be solved by using an organic acid and aminopolycarboxylic acid as a cleaning agent component. It came to be completed.
That is, the present invention is as follows.

<1> A cleaning agent used after a chemical mechanical polishing step of a semiconductor device having a copper wiring on the surface in a semiconductor device manufacturing process, and is represented by the following general formulas (I) to (IV) A cleaning agent containing at least one selected from aminopolycarboxylic acids.

(In the above general formulas (I) to (IV), R ¹ is an alkyl having at least one substituent selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a heterocyclic group, and a carbamoyl group. R ² , R ³ and R ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, and L represents a divalent linking group which may have a substituent.

<2> The cleaning agent according to <1>, wherein R ¹ in the general formula (I) is a carboxymethyl group or a carboxyethyl group.

<3> The cleaning agent according to <1> or <2>, wherein L in the general formula (II) is a methylene group or an ethylene group.
<4> In the general formula (III), R ² is a hydrogen atom, and the cleaning agent according to any one of the above <1> to <3>.
<5> The cleaning agent according to any one of <1> to <4>, wherein R ³ and R ⁴ in the general formula (IV) are carboxymethyl groups.

<6> The aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV) is α-alanine-N, N′-diacetic acid, β-alanine-N, N′-diacetic acid, glutamic acid. -N, N'-diacetic acid, iminodisuccinic acid, aspartic acid-N, N'-diacetic acid, S, S-ethylenediamine-N, at least one selected from the group consisting of N'-disuccinic acid The cleaning agent according to any one of <1> to <5> above.
<7> The aminopolycarboxylic acid is selected from the group consisting of α-alanine-N, N′-diacetic acid, glutamic acid-N, N′-diacetic acid, aspartic acid-N, N′-diacetic acid. It is a cleaning agent as described in <6> characterized by the above-mentioned.

<8> The cleaning agent according to any one of <1> to <7> above, which contains an organic acid.
<9> The cleaning agent according to <8>, wherein the organic acid is a polycarboxylic acid different from the aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV). is there.
<10> The above organic acid, wherein the organic acid is at least one selected from the group consisting of oxalic acid, malonic acid, maleic acid, tartaric acid, malic acid, citric acid, and salts thereof >.

<11> A cleaning method for a semiconductor device having a copper wiring on a surface, wherein the cleaning agent according to any one of <1> to <10> is used.

  A semiconductor device that is an object to be cleaned to which the cleaning agent of the present invention is applied is a substrate that has been subjected to a chemical mechanical polishing process in a semiconductor device manufacturing process. Either a layer substrate or a multilayer wiring substrate in which wiring is formed on the surface thereof via an interlayer insulating film or the like may be used. However, the present invention particularly applies metal wiring or a low dielectric constant (Low-k) insulating film on the surface. It is useful for cleaning a semiconductor device substrate that is partially or entirely.

Although the operation of the present invention is not clear, it is estimated as follows.
That is, if aminopolycarboxylic acid is used as an additive to the post-CMP cleaning liquid, the hydrophobic low dielectric constant insulating film and the surface of the semiconductor device on which the copper wiring is applied, while suppressing the corrosion and oxidation of the copper wiring, It is expected to improve the cleaning effect due to the chelating effect. However, since the solubility of aminopolycarboxylic acid, particularly solubility in acidic aqueous solution, is low, these expected cleaning effects are difficult to obtain sufficiently. Also, in actual semiconductor manufacturing sites, a concentrate of cleaning solution is purchased and diluted with pure water for use, so the solubility of the compound at a concentration higher than the concentration actually applied to the cleaning solution in the sales form. Is required. In the present invention, the aminopolycarboxylic acid having a specific structure is used as the aminopolycarboxylic acid, so that even in the concentration of the cleaning solution after dilution, the copper wiring is not corroded, and organic matter contamination and particle contamination existing on the surface of the semiconductor device are caused. It is estimated that the effect that can be effectively removed can be achieved.

  According to the present invention, there is provided a cleaning agent used in a cleaning process after a planarization polishing process in a semiconductor device manufacturing process, which is an organic substance present on the surface of a semiconductor device, in particular, the surface of a semiconductor device having copper wiring applied to the surface. Contamination and particle contamination can be effectively removed without causing corrosion of the copper wiring, and a cleaning agent capable of highly cleaning the substrate surface and a cleaning method using the same can be provided.

Hereinafter, specific embodiments of the present invention will be described.
The cleaning agent of the present invention contains at least one selected from aminopolycarboxylic acids represented by the following general formulas (I) to (IV) (hereinafter referred to as “specific aminopolycarboxylic acids”). After the chemical mechanical polishing step in the semiconductor device manufacturing process, it is preferably used for cleaning a semiconductor device, particularly a device surface having a copper wiring on the surface.
Hereinafter, each component contained in the cleaning agent of the present invention will be sequentially described.

<Specific aminopolycarboxylic acid>
The cleaning agent of the present invention contains at least one specific aminopolycarboxylic acid selected from aminopolycarboxylic acids represented by the following general formulas (I) to (IV). In the cleaning agent of the present invention, by containing the specific polyaminocarboxylic acid, organic residue present on the surface of the semiconductor device can be effectively removed without causing corrosion of the copper wiring, and the surface of the substrate can be removed. Can be highly purified.

In the general formulas (I) to (IV), R ¹ is an alkyl group having at least one substituent selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a heterocyclic group, and a carbamoyl group. Represents. R ² , R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group. L represents a divalent linking group which may have a substituent.

In the general formula (I), the alkyl group represented by R ¹ is preferably an alkyl group having 1 to 5 carbon atoms. The alkyl group represented by R ¹ is preferably an alkyl group having 1 to 5 carbon atoms having one or both of a carboxyl group and a hydroxyl group, more preferably 2 to 2 carbon atoms having a carboxyl group. 4 alkyl groups. Of these, R ¹ is preferably a carboxymethyl group or a carboxyethyl group because of its strong chelating power.

  In the general formula (II), the divalent linking group which may have a substituent represented by L is preferably a linking group having 1 to 5 carbon atoms, more preferably 1 to 2 carbon atoms. Are preferred. Examples of the substituent that the linking group has include a substituted or unsubstituted alkyl group and a hydroxyl group. The substituent for the alkyl group is not particularly limited, but is preferably a carboxyl group, a hydroxyl group, a carbamoyl group, an amino group, or a heterocyclic group. A more preferred substituent of the alkyl group is either one or both of a carboxyl group and a hydroxyl group.

The linking group represented by the L, _{such, -CH 2 -, - CH 2} CH 2 -, - CH 2 CH 2 CH 2 -, - CH (CH 3) -, - CH 2 CH (OH) - _{, -CH (CH 2 CO 2 H} ) -, - CH (CH 2 OH) -, - CH (CH 2 CH 2 OH) -, - CH (CH 2 CH 2 CO 2 H) -, - CH (CH ( _{OH) (CO 2 H))} - and the like.

  Among these, the linking group represented by L is particularly preferably an unsubstituted alkylene group or an alkylene group substituted with a carboxyalkyl group, and since the chelating power is strong, the alkylene group is a methylene group or an ethylene group. It is particularly preferred that

In the general formula (III), R ² represents a hydrogen atom or a substituted or unsubstituted alkyl group. Examples of the substituted alkyl group represented by R ² include a C 1-3 alkyl group having a carboxyl group or a hydroxyl group.
As the unsubstituted alkyl group this R ² represents preferably an alkyl group having 1 to 5 carbon atoms. Specifically, examples of the unsubstituted alkyl group represented by R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a butyl group.

As described above, R ² represents a hydrogen atom or a substituted or unsubstituted alkyl group, but is preferably an unsubstituted alkyl group or a hydrogen atom, and is a hydrogen atom from the viewpoint of biodegradability. It is more preferable.

In the general formula (IV), R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group.
Examples of the substituted alkyl group represented by R ³ and R ⁴ include an alkyl group having 1 to 3 carbon atoms having one or both of a carboxyl group and a hydroxyl group. Especially, as R < ³ > and R < ⁴ >, the alkyl group which has a carboxyl group is preferable, and since chelate power is strong, as R < ³ > and R < ⁴ >, it is more preferable that it is a carboxymethyl group.

The unsubstituted alkyl group represented by R ³ and R ⁴ is preferably an alkyl group having 1 to 5 carbon atoms. Specific examples of the unsubstituted alkyl group having 1 to 5 carbon atoms represented by R ³ and R ⁴ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a butyl group.

In addition, as described above, R ³ and R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group. Among them, a substituted alkyl group or a hydrogen atom is preferable, and a substituted alkyl group is preferable. Particularly preferred is a group.
When R ³ and R ⁴ are substituted alkyl groups, the substituents of the alkyl groups representing R ³ and R ⁴ may be the same or different, but the chelating power From the viewpoint of the above, the same substituent is preferable.

  The specific aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV) may include an optically active carbon atom. When the specific aminopolycarboxylic acid contains an optically active carbon atom, the absolute configuration is preferably a left-handed body (hereinafter referred to as “S-form”). Specifically, in the specific aminopolycarboxylic acid represented by any one of the above general formulas (I) to (IV), the absolute configuration of the carbon atom substituted with the unsubstituted alkyl group is S-form, Either the R-form or the racemate may be used, but the absolute configuration of the carbon atom substituted with the alkyl group having a substituent is preferably the S-form. This is because biodegradability is good.

  The specific aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV) may be an acid (H form) or a salt thereof (for example, sodium salt, potassium salt, ammonium salt). Although it is good, an acid is preferable.

Although the specific example of a compound represented by the said general formula (I) is given to the following, it is not limited to these.

  Among these, (I-1), (I-4), and (I-5) are preferable, and (I-4) is particularly preferable from the viewpoint of chelating power.

  Moreover, although the specific example of a compound represented by the said general formula (II) is given to the following, it is not limited to these.

  Among these, the above (II-3) is particularly preferable from the viewpoint of chelating power.

  Moreover, although the specific example of a compound represented by the said general formula (III) is given to the following, it is not limited to these.

  Among these, III-1 is particularly preferable from the viewpoint of chelating power.

Moreover, although the specific example of a compound represented by the said general formula (IV) is given to the following, it is not limited to these.

  Among these, IV-2 is particularly preferable from the viewpoint of chelating power.

  The cleaning agent in the present invention may contain only one kind of the specific aminopolycarboxylic acid represented by the above general formula (I) to general formula (IV), or two or more kinds thereof. May be.

  The total content of the specific aminopolycarboxylic acid in the cleaning agent of the present invention depends on the solubility of the compound, but is preferably 0.001% by mass to 30% by mass in 1 L of the cleaning liquid, and preferably 0.03% by mass to 10%. It is more preferable that it is mass%, and it is more preferable that it is 0.1 mass%-5 mass%.

  Here, the cleaning agent of the present invention is an aqueous solution. That is, it is necessary to include at least one of the specific aminopolycarboxylic acids represented by the general formula (I) to the general formula (IV), and other components used in combination are contained in the aqueous solvent. What melt | dissolves is preferable. As the water used as the solvent, it is preferable to use deionized water or ultrapure water which does not contain impurities or has its content reduced as much as possible from the viewpoint of effect. From the same viewpoint, electrolytic ionic water obtained by electrolysis of water, hydrogen water in which hydrogen gas is dissolved in water, or the like can also be used.

<Organic acid>
The cleaning agent of the present invention preferably contains an organic acid in addition to the specific aminopolycarboxylic acid, which is an essential component, and water as a solvent, as long as the effects of the present invention are not impaired.
The organic acid in the present invention is an organic compound that exhibits acidity (pH <7) in water, and has at least an acidic functional group such as a carboxyl group, a sulfo group, a phenolic hydroxyl group, or a mercapto group in the molecule. An organic compound having one. In addition, the organic acid in this invention is a structure different from the specific amino polycarboxylic acid demonstrated above.

As the organic acid, one selected from the following group is suitable.
Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2-methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid , N-octanoic acid, 2-ethylhexanoic acid, benzoic acid, glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, Examples thereof include tartaric acid, citric acid, lactic acid, and further ammonium salts and alkali metal salts thereof.

As the organic acid, a compound containing at least two carboxyl groups in the molecule is preferable among the above groups. Examples of the compound containing at least two carboxyl groups in the molecule include dicarboxylic acids such as oxalic acid, malonic acid, succinic acid and maleic acid, oxypolycarboxylic acids such as tartaric acid, malic acid and citric acid, and salts thereof. Etc.
Among these, citric acid, malonic acid, maleic acid, and succinic acid are preferable, and citric acid and maleic acid are more preferable from the viewpoints of material safety, cost, and cleaning performance.

  In the cleaning agent of the present invention, the organic acid may be used alone or in combination of two or more at any ratio. The content of the organic acid in the cleaning agent of the present invention is preferably 0.001% by mass to 30% by mass, more preferably 0.01% by mass to 10% by mass in 1 L of the cleaning liquid, although it depends on the solubility of the compound. More preferably, the content is 1% by mass to 3% by mass.

<Other ingredients>
In the cleaning agent of the present invention, various compounds are used in combination as optional components depending on the purpose in addition to the specific aminopolycarboxylic acid which is an essential component and water as a solvent, as long as the effects of the present invention are not impaired. be able to. Hereinafter, additives which are optional components will be described.
Examples of the additive include a surfactant and a chelating agent.

(Surfactant)
The detergent of the present invention can contain a surfactant.
Examples of the anionic surfactant include carboxylate, sulfonate, sulfate ester salt, and phosphate ester salt. Examples of the carboxylate salt include soap, N-acyl amino acid salt, polyoxyethylene, or polyoxypropylene. Alkyl ether carboxylate, acylated peptide; sulfonate, alkyl sulfonate, sulfosuccinate, α-olefin sulfonate, N-acyl sulfonate; sulfate ester, sulfated oil, alkyl sulfate Alkyl ether sulfates, polyoxyethylene or polyoxypropylene alkyl allyl ether sulfates, alkyl amide sulfates; phosphoric acid ester salts such as alkyl phosphates, polyoxyethylene or polyoxypropylene alkyl allyl ether phosphates be able to.

  In addition, preferable anionic surfactants in the present invention include those having at least one aromatic ring structure in the molecule, and examples of the aromatic ring include a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, and a phenanthrene. Ring, chrysene ring, pyrene ring and the like.

Examples of the anionic surfactant that can be suitably used in the present invention include, for example, alkylbenzene sulfonic acid and its salt, alkyl naphthalene sulfonic acid and its salt, alkyl diphenyl ether sulfonic acid and its salt, alkyl diphenyl ether disulfonic acid and its salt, Examples thereof include phenolsulfonic acid formalin condensates and salts thereof, arylphenolsulfonic acid formalin condensates and salts thereof, and the like.
In the anionic surfactants listed above, the alkyl group introduced into the aromatic ring may be either a linear type or a branched type, and has 2 to 30 carbon atoms (preferably 3 to 3 carbon atoms). 22) is preferred, and examples thereof include propyl, butyl, pentyl, hexyl, octyl, nonyl, decyl, dodecyl, hexadecyl, octadecyl and the like. The alkyl group may be linear or branched.
Moreover, when these anionic surfactants take a salt structure, examples of the salt structure include sodium salt, potassium salt, ammonium salt, triethanolamine salt, tetramethylammonium salt and the like.
More specific examples of these anionic surfactants include, for example, dodecylbenzenesulfonic acid, dodecyldiphenyl ether disulfonic acid, diphenyl ether disulfonic acid, propylnaphthalenesulfonic acid, propylnaphthalenesulfonic acid, triisopropylnaphthalenesulfonic acid, dodecylbenzene. Examples include ammonium sulfonate and ammonium dodecyl diphenyl ether sulfonate.

  Other examples of the anionic surfactant that can be used in the present invention include, in addition to the aromatic ring structure in the molecule, for example, substitution of polyoxyethylene group, polyoxypropylene group, fluoroalkyl group, acetylene group, hydroxyl group, etc. Examples of the surfactant further include a group, and more specific examples include polyoxyethylene tristyryl phenyl ether phosphate, phenolsulfonic acid formalin condensate, and the like.

  Among the above-mentioned anionic surfactants, dodecylbenzene sulfonic acid, dodecyl diphenyl ether disulfonic acid, and polyoxyethylene tristyryl phenyl ether phosphate are more preferable.

Commercially available products may be used as the anionic surfactant. For example, Perex NBL (sodium alkylnaphthalene sulfonate, manufactured by Kao Corporation), Neoperex GS (Dodecylbenzenesulfonic acid, manufactured by Kao Corporation), Neo Perex GS-15 (sodium dodecylbenzenesulfonate, manufactured by Kao Corporation), Perex SS-L (sodium alkyldiphenyl ether disulfonate, manufactured by Kao Corporation), demole NL (sodium of formalin condensate of β-naphthalene sulfonic acid) Salt, manufactured by Kao Corporation) and the like can be suitably used.
One of these anionic surfactants may be used alone for the cleaning agent of the present invention, or two or more thereof may be used in combination at any ratio.

Other preferred examples of the surfactant that can be used in the present invention include nonionic surfactants.
Nonionic surfactants include ether type, ether ester type, ester type, and nitrogen-containing type. As ether type, polyoxyethylene alkyl and alkylphenyl ether, alkylallyl formaldehyde condensed polyoxyethylene ether, polyoxyethylene Examples include polyoxypropylene block polymers and polyoxyethylene polyoxypropylene alkyl ethers. As ether ester types, 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, sucrose ester, a nitrogen-containing type, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amide, and the like.
In addition, fluorine surfactants, silicone surfactants, and the like can be given.

In the case of containing a plurality of kinds of surfactants, two or more kinds of anionic surfactants may be used, or an anionic surfactant and a nonionic surfactant may be used in combination.
The total content of the surfactant in the cleaning agent of the present invention is preferably 0.001 g to 10 g, more preferably 0.01 g to 1 g, and more preferably 0.02 g to 0 g in 1 L of the cleaning agent. It is especially preferable to set it as 0.5 g.

(Chelating agent)
The cleaning agent of the present invention may contain a chelating agent as necessary in order to reduce the influence of mixed polyvalent metal ions and the like. As a chelating agent, a general-purpose hard water softening agent that is a precipitation inhibitor of calcium or magnesium or an analogous compound thereof can be used, and two or more of these 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, and is generally about 5 ppm to 10,000 ppm in the cleaning agent.

  Examples of the chelating agent include aminocarboxylic acids or aminocarboxylic acid salts, aminopolycarboxylic acids or aminopolycarboxylic acid salts, glycine as aminocarboxylic acids, and diethylenetriaminepentaacetic acid (DTPA) as aminopolycarboxylic acid salts. , Ethylenediaminetetraacetic acid (EDTA), and the like, and further ammonium salts and alkali metal salts thereof.

[PH]
The pH of the cleaning agent of the present invention is not particularly limited, and should be appropriately selected and adjusted in the range of about pH 0.5 to 12 depending on the characteristics of the device that is symmetrical to cleaning and the type of impurities to be removed. Can do.
The pH value may be used as long as it is in a preferable range when the cleaning agent is adjusted. If it is necessary to control the pH after the cleaning solution is prepared, an organic acid or an organic alkaline agent is added. Can be easily adjusted. For pH adjustment of the cleaning agent, it is possible to use a general pH adjuster, for example, an acid such as an inorganic acid such as nitric acid or sulfuric acid, and an alkali such as potassium hydroxide or ammonia. Considering the influence on the surface of the substrate, a general pH adjusting agent as described above is not used, and the pH is adjusted with an organic acid or an organic alkali agent, specifically, for example, oxalic acid, tetramethylammonium hydroxide, or the like. It is preferable to adjust.

  The cleaning agent of the present invention is suitably used for cleaning a substrate for a semiconductor device having a metal or metal compound layer on its surface or a wiring formed of these. Since the cleaning agent of the present invention has no concern about causing corrosion or oxidation to the copper wiring, it can be particularly suitably used for cleaning a semiconductor device substrate having a copper wiring on the surface.

The semiconductor device cleaning method of the present invention will be described below.
<Washing method>
The semiconductor device cleaning method of the present invention is characterized by using the cleaning agent of the present invention, and is performed subsequent to a chemical mechanical polishing step (CMP step) in semiconductor device manufacturing. .

Usually, in the CMP process, a polishing liquid is supplied to a polishing pad on a polishing surface plate and brought into contact with a surface to be polished such as a substrate for a semiconductor device, which is an object to be polished, and the surface to be polished and the polishing pad are moved relative to each other for polishing. In the subsequent cleaning step, the semiconductor device substrate that has been polished is placed on a spinner, and the cleaning agent is supplied at a flow rate of 100 to 2000 ml / min. In general, a cleaning method is used in which the substrate is supplied to the substrate surface under the above conditions and brush scrubbed at room temperature for 10 to 60 seconds.
Cleaning can also be performed using a commercially available cleaning tank. For example, a wafer cleaning machine (trade name: ZAB8W2M) manufactured by MAT is used, and a PVA roll brush is brought into contact with a scrubbing unit built in the apparatus. It can also be performed by scrub cleaning.

As a metal used for the substrate for a semiconductor device which is an object to be polished, W or Cu is mainly mentioned. In recent years, LSIs using copper with low wiring resistance have been developed.
With the miniaturization of wiring aiming at higher density, it is necessary to improve the conductivity and electronic migration resistance of copper wiring, and high productivity can be demonstrated without contaminating these high-definition and high-purity materials. Technology is required.
As a process of cleaning a substrate having Cu on the surface and further having a low dielectric constant insulating film as an interlayer insulating film and having a copper wiring on the surface, CMP was performed particularly on the Cu film. Examples include a subsequent cleaning process, and a cleaning process after opening a hole in the interlayer insulating film on the wiring by dry etching. In these cleaning processes, impurities such as impurities and particles existing on the surface are efficiently removed. This is particularly important for maintaining the purity and accuracy of the wiring. From such a viewpoint, the cleaning agent of the present invention is preferably used in these cleaning steps. Further, as described above, since the cleaning agent of the present invention does not cause corrosion or oxidation on the copper wiring, the cleaning agent of the present invention is also preferably used from this viewpoint.
The cleaning agent of the present invention is also preferably used for the purpose of efficiently removing the passive film forming agent residue adsorbed on the copper wiring surface.

  In order to confirm the effect of removing impurities in the cleaning process, it is necessary to detect foreign matter on the wafer. In the present invention, as a device for detecting foreign matter, a defect inspection apparatus ComPLUS3 manufactured by Applied Materials technology and Applied Materials are used. A Review SEM observation device manufactured by technology, SEM vision G3, is preferably used.

According to the cleaning method of the present invention, the impurity metal on the surface of the semiconductor device substrate that has completed the CMP process, the substrate material, the impurity inorganic material including the polishing scraps of the interlayer insulating film, and the organic material including the residue of the passive film forming agent Particles such as abrasive grains can be removed efficiently, especially for devices that require high-precision wiring, and multilayers that form a new interlayer insulating film and wiring after flattening a single-layer substrate When planarizing a wiring board or the like, it is suitable for cleaning a device that requires efficient removal of impurities in each step. Further, even when the semiconductor device substrate has copper wiring, the copper wiring is not corroded or oxidized.
Hereinafter, the present invention will be described by way of examples. The present invention is not limited to these examples.

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

<Preparation of polishing liquid>
・ Colloidal silica (abrasive grains: average particle diameter 30 nm) 5 g / L
・ Benzotriazole (BTA) 1g / L
・ Glycine 10g / L
Pure water was added to make a total volume of 1000 mL, and the pH was adjusted to 4.5 using nitric acid and ammonia.
15% hydrogen peroxide (oxidant) 15 g / L was added to the polishing liquid immediately before polishing.

<Cu wafer polishing>
Polishing Rate Evaluation 8 inch Wf Polishing A device “LGP-612” manufactured by Lapmaster was used as a polishing device, and the film provided on each wafer was polished under the following conditions while supplying slurry.
Base: 8 inch SEMATECH 854 silicon wafer with copper wiring pattern Table rotation speed: 64 rpm
Head rotation speed: 65rpm
(Processing linear velocity = 1.0 m / s)
Polishing pressure: 140 hPa
Polishing pad: Rohm and Haas
Part No. IC-1400 (K-grv) + (A21)
Slurry supply rate: 200 ml / min

<Preparation of cleaning solution>
[Example 1]
・ Citric acid [organic acid] 50.00 g / L
Specific aminopolycarboxylic acid represented by the specific example (I-1) 50.00 g / L
The above components were mixed to prepare a cleaning liquid concentrate, which was further diluted with pure water to obtain the cleaning liquid of Example 1. The dilution ratio was a washing ratio: pure water = 1: 40 by mass ratio.

[Examples 2 to 22, Comparative Examples 1 to 6]
<Adjustment of cleaning liquid>
In the preparation of the cleaning liquid of Example 1, an organic acid, a specific aminopolycarboxylic acid and an organic alkaline agent were mixed in the compositions shown in Tables 1 and 2 below, and diluted at the dilution ratios shown in Tables 1 and 2 below. In the same manner as in Example 1, the cleaning liquids of Examples 2 to 22 and Comparative Examples 1 to 6 were prepared.
In Tables 1 and 2, tetrazole is 1H-tetrazole, and TMAH is tetramethylammonium hydroxide.

<Cleaning test>
Using the cleaning agents of Examples 1 to 22 and Comparative Examples 1 to 6 adjusted according to the above prescription, the silicon substrate with a copper film polished under the above conditions is cleaned using the polishing liquid. A cleaning test was performed. When the cleaned substrate was visually confirmed, no corrosion was observed on any of the substrates when the cleaning agents of Examples 1 to 22 were used.
The cleaning was performed by scrub cleaning with a PVA roll brush in contact with a scrub part built in a wafer cleaning apparatus manufactured by MAT, ZAB8W2M. The cleaning solution is allowed to flow for 25 seconds at 400 ml / min on the upper side and 400 ml / min on the lower side, and then pure water (deionized water) is allowed to flow for 650 ml / min on the upper side of the polishing substrate and for 35 seconds at 500 ml / min on the lower side. Further, the treatment was performed for 30 seconds with a spin dry device incorporated in the above device.

<Evaluation of organic residue removal performance>
The removal performance evaluation of the organic residue remaining on the surface of the Cu wafer washed and dried with the cleaning agents of Examples 1 to 22 and Comparative Examples 1 to 6 was performed. These surface states are confirmed by using a defect inspection apparatus ComPLUS3 manufactured by Applied Materials technology, and randomly extracting 100 defects from the detected defects, and using a Revive SEM observation apparatus, SEM vision3 manufactured by Applied Materials technology. Then, the image income was calculated, classification was performed for each defect type, the ratio of each defect type was determined, and the number of wafers for each defect type was calculated. Evaluation is performed according to the following criteria, and the results are shown in Table 1 and Table 2 below.

-Evaluation criteria-
○: The number of organic residue on the wafer per 1 cm ² is 0 or more and less than 0.1 Δ: The number of organic residue on the wafer per 1 cm ² is 0.1 or more and less than 1 ×: per 1 cm ² The number of organic residue on the wafer is 1 or more

  In Table 1, the ratio of the cleaning liquid to pure water in the “dilution ratio” column is based on mass. The “specific aminopolycarboxylic acid (I-1)” is specific examples (I-1) to (I-6) and (II-1) to (II-5) of the specific aminopolycarboxylic acid. Specific example (I-1) among (III-1) to (III-2) and (IV-1) to (IV-2) is represented. The same applies to other specific examples.

As can be seen from Tables 1 and 2, when cleaning is performed using the cleaning agents of Examples 1 to 22 after the CMP process, organic residue adhering to the surface can be effectively cleaned and removed. I understand.
On the other hand, when the cleaning agents of Comparative Examples 1 to 6 that do not contain the specific aminopolycarboxylic acid are used, the removability of organic residue is inferior compared to the case of using the cleaning agents of Examples 1 to 22. I understood. Moreover, the cleaning agents of Comparative Examples 1 to 6 were inferior in organic residue removal and corrosion was also observed.
Furthermore, in Examples 16 and 17 containing only the specific aminopolycarboxylic acid without containing an organic acid, the cost for obtaining the equivalent performance is higher, and the configuration further containing the organic acid has a lower cost and higher performance. Obtained.
Thus, it was found that the cleaning agents of Examples 1 to 22 were excellent in cleaning properties while maintaining the corrosion inhibition of the copper wiring applied to the Cu wafer, and having excellent organic residue removability. .

Claims (11)

In a semiconductor device manufacturing process, a cleaning agent used after a chemical mechanical polishing process of a semiconductor device having a copper wiring on the surface,
A cleaning agent containing at least one selected from aminopolycarboxylic acids represented by the following general formula (I) to general formula (IV).

(In the above general formulas (I) to (IV), R ¹ is an alkyl having at least one substituent selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, a heterocyclic group, and a carbamoyl group. R ² , R ³ and R ⁴ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, and L represents a divalent linking group which may have a substituent. The cleaning agent according to claim 1, wherein in the general formula (I), R ¹ is carboxymethyl group or carboxyethyl group.   The cleaning agent according to claim 1 or 2, wherein L in the general formula (II) is a methylene group or an ethylene group. The cleaning agent according to any one of claims 1 to 3, wherein R ² in the general formula (III) is a hydrogen atom. In the general formula (IV), R ³ and R ^4, the cleaning agent according to any one of claims 1 to 4, characterized in that the carboxymethyl group.   The aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV) is α-alanine-N, N′-diacetic acid, β-alanine-N, N′-diacetic acid, glutamic acid-N, It is at least one selected from the group consisting of N′-diacetic acid, iminodisuccinic acid, aspartic acid-N, N′-diacetic acid, S, S-ethylenediamine-N, N′-disuccinic acid. The cleaning agent according to any one of claims 1 to 5.   The aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV) is α-alanine-N, N′-diacetic acid, glutamic acid-N, N′-diacetic acid, aspartic acid-N, N The cleaning agent according to claim 6, wherein the cleaning agent is selected from the group consisting of '-diacetic acid.   The cleaning agent according to claim 1, comprising an organic acid.   The cleaning agent according to claim 8, wherein the organic acid is a polycarboxylic acid different from the aminopolycarboxylic acid represented by the general formula (I) to the general formula (IV).   10. The organic acid according to claim 9, wherein the organic acid is at least one selected from the group consisting of oxalic acid, malonic acid, maleic acid, tartaric acid, malic acid, citric acid, and salts thereof. Washing soap. A cleaning method for a semiconductor device having copper wiring on a surface, wherein the cleaning agent according to any one of claims 1 to 10 is used.