JP6488740B2 - Substrate cleaning liquid for semiconductor device and method for cleaning semiconductor device - Google Patents

Description

  The present invention relates to a cleaning solution for a substrate for a semiconductor device and a method for cleaning a substrate for a semiconductor device, and more particularly, after chemical mechanical polishing, the surface of the substrate for a semiconductor device having a metal such as Cu exposed on the surface is effectively used. And a cleaning method using the cleaning liquid.

  A substrate for a semiconductor device is formed by depositing a deposited layer of a metal film or an interlayer insulating film to be a wiring on a silicon wafer substrate, and then using chemical-mechanical polishing (Chemical-mechanical polishing (Chemical) Mechanical Polishing (hereinafter referred to as “CMP”) is carried out to planarize the surface by the process and to stack new layers on the planarized surface. In fine processing of a substrate for a semiconductor device, high-precision flatness is required in each layer, and the importance of planarization by CMP is increasing.

  In the semiconductor device manufacturing process, a wire (Cu wire) made of a copper (Cu) film having a low resistance value has been introduced in order to increase the speed and integration of the device. In addition, a barrier metal layer is used between them for the purpose of preventing Cu from diffusing into the interlayer insulating film. As the barrier metal, tantalum (Ta), a tantalum compound, titanium (Ti), a titanium compound, ruthenium (Ru), a ruthenium compound, cobalt (Co), a cobalt compound, etc. are often used mainly as a barrier metal. Corrosion is likely to occur from the interface of Cu wiring and barrier metal.

Cu is suitable for fine processing because of its good processability, but it is easily corroded by acid components and alkali components, so that oxidation and corrosion of the Cu wiring become a problem in the CMP process.
Therefore, conventionally, in CMP of a semiconductor device substrate having a Cu wiring, an anticorrosive such as benzotriazole, tolyltriazole or derivatives thereof is added to the polishing agent, and this anticorrosive is strongly coordinated to the Cu oxide film. By forming a protective film, corrosion of Cu wiring in CMP is suppressed (for example, Patent Document 1).

Abrasive grains such as colloidal silica used in the CMP step, organic residues derived from the anticorrosive agent contained in the slurry, etc. are present in large amounts on the surface of the substrate for semiconductor devices after the CMP step, so these are removed Therefore, the semiconductor device substrate after the CMP process is subjected to a cleaning process.
In cleaning after CMP, an acidic cleaning solution and an alkaline cleaning solution are used. In an acidic aqueous solution, colloidal silica is positively charged, the substrate surface is negatively charged, an electrical attraction is exerted, and removal of colloidal silica becomes difficult. In contrast, OH in an alkaline aqueous solution ^- because of the presence of abundant, colloidal silica and the substrate surface is both negatively charged, serve electrical repulsion, the removal of the colloidal silica is easily performed. However, on the other hand, there is also a disadvantage that the Cu surface is oxidized.

  In order to prevent this oxidative degradation and corrosion, a method has been proposed in which an anticorrosive is added to the cleaning solution used in the cleaning step, but the anticorrosive used conventionally in CMP is Cu ion eluted from Cu wiring There is a problem that a complex is formed to generate a residue having adhesion to a substrate. In addition, when an anticorrosive agent with little residue formation known so far is used, the above-mentioned residue is not formed, but there is a problem that suppression of oxidation deterioration and corrosion of Cu wiring becomes insufficient.

Patent Document 2 discloses a composition for cleaning a processed semiconductor material having a pH of about 10 to 13 containing, as a corrosion inhibiting compound, imidazole, mercaptomethylimidazole or the like in a detergent selected from the group of ammonium hydroxide and tetraalkylammonium hydroxide. Objects are disclosed. Patent Document 3 discloses a composition for cleaning a semiconductor workpiece in a neutral to low pH range (about 2 to 6), and includes ammonium citrate, ammonium oxalate, aspartic acid, benzoic acid, Detergents selected from the group consisting of citric acid, cysteine, glycine, gluconic acid, glutamic acid, histidine, maleic acid, oxalic acid, propionic acid, salicylic acid, tartaric acid and mixtures thereof, and ascorbic acid, benzotriazole, caffeic acid , Cinnamic acid, cysteine, glucose, imidazole, mercaptothiazoline, mercaptoethanol, mercaptopropionic acid, mercaptobenzothiazole, mercaptomethylimidazole, tannic acid, thioglycerol, thiosalicylic acid, triazole, vanillin, vanillin And compositions comprising corrosion inhibiting compound selected from among the group consisting of mixtures thereof is described.

Patent No. 4406554 Japanese Patent Publication No. 2007-525836 Japanese Patent Publication No. 2007-526647

In the substrate cleaning solution for semiconductor devices described in Patent Documents 2 and 3 described above, a cleaning solution having a sufficient function in terms of both suppression of corrosion of copper used for wiring and metal used for barrier metal and avoidance of residue formation. It can not be said that, in the conventional conventional washing | cleaning liquid especially in the washing | cleaning liquid of an alkali type, what compatible with these was not found.
Under such circumstances, the object of the present invention is to be used in a cleaning process after a CMP process in a substrate for a semiconductor device, in particular a substrate for a semiconductor device having a metal wiring and a barrier metal on the surface, It is an object of the present invention to provide a cleaning solution and a cleaning method which can suppress the generation of residue and the adhesion of the residue to the substrate surface.

MEANS TO SOLVE THE PROBLEM As a result of repeating earnest research so that the said subject might be solved, the present inventors discovered that the following invention met the said objective, and came to this invention.
That is, the gist of the present invention relates to the following invention.
[1] A substrate cleaning solution for semiconductor devices having a pH of 8 or more containing the following components (A) to (D), wherein the concentration of (B) in the cleaning solution is 0.001 to 2 mass%, Substrate cleaning solution for semiconductor devices.

  (A) a compound represented by the following general formula (1)

(In the above formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² represents a carboxyl group, a carbonyl group, a functional group having an ester bond, an alkyl group having 1 to 4 carbon atoms, or R ³ represents a hydrogen atom, an acetyl group, or an alkyl group having 1 to 4 carbon atoms.
(B) Azole-based compound (C) pH adjuster (D) Water [2] Component (A) described in [1], wherein the compound represented by the general formula (1) is histidine and a derivative thereof or a salt thereof Substrate Cleaning Liquid for Semiconductor Device [3] The component (B) azole compound is imidazole, N-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2- It is 1 or more types selected from the group which consists of phenylimidazole, a triazole, a pyrazole, a thiazole, an oxazole, and a pyrrole, The board | substrate washing | cleaning liquid for semiconductor devices as described in [1] or [2] characterized by the above-mentioned.
[4] The component (C) pH adjuster comprises an inorganic alkali compound containing an alkali metal and / or an alkaline earth metal or an organic quaternary ammonium hydroxide represented by the following formula (2): The substrate washing | cleaning liquid for semiconductor devices as described in any one of [1]-[3].

_{^{(R) 4 N + OH -}} ··· (2)
(In the above formula (2), R represents a hydroxyl group, an alkoxy group, or an alkyl group which may be substituted with halogen, and all four Rs may be the same or different from each other.)
[5] The substrate cleaning liquid for a semiconductor device according to any one of [1] to [4], which further contains a component (E) a chelating agent.
[6] The substrate cleaning liquid for a semiconductor device according to any one of [1] to [5], further comprising a component (F) surfactant.
[7] The component (E) chelating agent is at least one selected from the group consisting of diaminopropane, oxalic acid, citric acid, tartaric acid, malic acid, picolinic acid, glycine and iminodiacetic acid The substrate washing | cleaning liquid for semiconductor devices as described in [5] or [6].
[8] The substrate cleaning solution for a semiconductor device according to [6], wherein the component (F) surfactant is an anionic surfactant.
[9] The above anionic surfactant comprises alkyl sulfonic acid and its salt, alkyl benzene sulfonic acid and its salt, alkyl diphenyl ether disulfonic acid and its salt, alkyl methyl taurate and its salt, and sulfosuccinic acid diester and its salt It is at least 1 sort (s) chosen from, The board | substrate washing | cleaning liquid for semiconductor devices as described in [8] characterized by the above-mentioned.
[10] The substrate cleaning liquid for a semiconductor device according to any one of [1] to [9], further comprising a component (G) a reducing agent.
[11] The substrate cleaner for a semiconductor device according to [10], wherein the component (G) reducing agent is ascorbic acid ascorbic acid or a salt thereof and / or gallic acid or a salt thereof.
[12] A method for cleaning a substrate for semiconductor device, comprising cleaning the substrate for semiconductor device using the cleaning liquid for a substrate for semiconductor device according to any one of [1] to [11]. [13] The cleaning of a substrate for a semiconductor device according to claim 12, characterized in that the substrate for a semiconductor device has a Cu wiring on the surface of the substrate and is a substrate after chemical mechanical polishing is performed. Method.

  By using the substrate cleaning solution for semiconductor devices of the present invention, corrosion of copper interconnections of metal interconnections is prevented in the cleaning step of semiconductor device substrates after the CMP step, and corrosion of barrier metals, particularly cobalt and cobalt metal, is suppressed. Thus, the generation of residues and the adhesion of the residues to the substrate surface can be suppressed to enable efficient post-CMP cleaning.

  Hereinafter, although an embodiment of the present invention is described concretely, it is not limited to the following embodiment, and can be variously changed and carried out within the limits of the gist.

Substrate cleaning solution for semiconductor devices
The substrate cleaning solution for semiconductor devices of the present invention (hereinafter sometimes referred to as "the cleaning solution of the present invention") is used for cleaning a substrate for semiconductor devices, preferably in a chemical mechanical polishing (CMP) process in semiconductor device manufacture. The cleaning liquid used in the cleaning step of a substrate for a semiconductor device to be performed later is characterized in that the cleaning liquid contains the following components (A) to (D) and has a pH of 8 or more.

  (A) a compound represented by the following general formula (1)

(In the above formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² represents a carboxyl group, a carbonyl group, a functional group having an ester bond, an alkyl group having 1 to 4 carbon atoms, or R ³ represents a hydrogen atom, an acetyl group, or an alkyl group having 1 to 4 carbon atoms.
(B) Azole-based compound (C) pH adjuster (D) Water As described above, in the alkaline aqueous solution, OH ^- is abundantly present, so the particle surface of colloidal silica etc. is negatively charged and the object to be cleaned is The substrate surface is also negatively charged. By controlling the zeta potential in the liquid to the same sign, an electrical repulsive force is generated. As a result, the removal of the particles from the substrate surface can be facilitated, and the particles once removed can be prevented from reattaching to the substrate surface.

In addition, pH at the time of use of the washing | cleaning liquid of this invention can be adjusted with the addition amount of each component contained in a washing | cleaning liquid. The pH of the cleaning solution of the present invention is 8 or more, preferably 10 or more. Further, the upper limit is not particularly limited, but since it is an aqueous solution, the upper limit of pH is usually 14 or less, more preferably 13 or less.
Usually, in an alkaline solution, Cu (hereinafter sometimes referred to as “Cu wiring”) present as a wiring or the like on the surface of a substrate for a semiconductor device is oxidized to its surface to form copper oxide. Copper oxide is dissolved by the component having a chelating action in the cleaning solution and causes corrosion. However, in the present invention, the anticorrosion action of the component (B) in the cleaning solution can prevent the dissolution of the Cu wiring.

  Generally, in order for an anticorrosive to exhibit anticorrosion performance, a film of a copper-anticorrosive complex is formed on the surface of a wiring, and it is required that the film has low solubility. However, if the solubility of the copper-corrosion agent complex is too low, it can not be removed in the washing step, and there is a problem that it remains as a crystal or an organic residue on the Cu wiring. In the acid solution, the dissociation of the amino group and the carboxyl group is small, the solubility of the copper-corrosion agent complex is low, and it remains as crystals on the Cu wiring, whereas in the alkaline aqueous solution, the copper-corrosion agent complex is Solubility improves and it becomes difficult to remain on Cu wiring.

  In the present invention, when component (A) tries to dissolve (corrode) metal surfaces such as copper and barrier metal on the substrate surface, the presence of the azole compound of component (B) causes the azole compound to It is speculated that coordination of the non-covalent electron pair of the azole compound of component (B) (= substitution of imidazole) is delayed and corrosion is suppressed when the non-covalent electron pair having is coordinated to the metal surface. Ru.

From the above, in the cleaning liquid of the present invention, the presence of the above components (A) to (D) at pH 8 to 14 has sufficient corrosion resistance to metal wiring and barrier metal, and generation of residue and residue on the substrate surface Can be suppressed.
Hereinafter, the respective components contained in the cleaning solution of the present invention will be described in detail along with the actions thereof.

<Component (A) Compound Represented by General Formula (1)>
The component (A) contained in the cleaning liquid of the present invention is a compound represented by the following general formula (1): an impurity metal such as tungsten or cobalt, which is contained in metal wiring on the substrate surface; It has an action of dissolving and removing the insoluble metal complex of the anticorrosive agent and copper present in the rally by the chelating action.

(In the above formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² represents a carboxyl group, a carbonyl group, a functional group having an ester bond, an alkyl group having 1 to 4 carbon atoms, or R ³ represents a hydrogen atom, an acetyl group, or an alkyl group having 1 to 4 carbon atoms.
In formula (1), R ¹ and R ³ are preferably carboxyl groups. R2 is preferably a hydrogen atom.
Among the compounds represented by the formula (1) of the component (A), specifically preferred is histidine and / or a derivative thereof, or a salt thereof.

<Component (B) azole compound>
Although the component (B) contained in the washing | cleaning liquid of this invention is an azole compound, it has the effect | action which prevents the melt | dissolution of a metal. In particular, when the barrier metal is cobalt, it works more effectively.
Among azole compounds, specifically, preferably, imidazole, N-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, triazole, It is one or more selected from the group consisting of pyrazole, thiazole, oxazole and pyrrole, more preferably imidazole, triazole and thiazole, and particularly preferably imidazole.

  Component (B) The azole compound is characterized in that it is 0.001 to 2% by mass. Preferably, it is 0.005 to 1.5% by mass, and more preferably 0.01 to 1% by mass. If this concentration exceeds 2% by mass, corrosion of copper, barrier metal or the like may proceed, and if less than 0.001% by mass, the effect of corrosion prevention of copper, barrier metal or the like may be reduced.

<Component (C) pH adjuster>
The component (C) pH adjuster contained in the cleaning liquid of the present invention is not particularly limited as long as it can be adjusted to a target pH, and an acid compound or an alkali compound can be used. As the acid compound, inorganic acids such as sulfuric acid and nitric acid and salts thereof, or organic acids such as acetic acid and lactic acid and salts thereof are mentioned as preferable examples.

Further, as the alkali compound, an organic alkali compound and an inorganic alkali compound can be used. Examples of organic alkali compounds include salts of quaternary ammonium and its derivatives such as organic quaternary ammonium hydroxide, alkylamines such as trimethylamine and triethylamine and salts of their derivatives, alkanolamines such as monoethanolamine, and the like. Derivatives are mentioned as suitable examples.
In the cleaning agent of the present invention, as the component (C) pH adjuster to be used, preferably, an inorganic alkali compound containing an alkali metal and / or an alkaline earth metal or an organic quaternary ammonium represented by the following formula (2) It is a hydroxide.

_{^{(R) 4 N + OH -}} ··· (2)
(In the above formula (2), R represents a hydroxyl group, an alkoxy group, or an alkyl group which may be substituted with halogen, and all four Rs may be the same or different from each other.)
In the above general formula (2), R is a linear or branched alkyl group having 1 to 4 carbon atoms which may be substituted with a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or halogen, particularly straight chain It is preferable that it is a C1-C4 alkyl group of a chain, and / or a linear C1-C4 hydroxyalkyl group. Examples of the alkyl group for R include lower alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, propyl and butyl groups, and all four R ¹ in the above general formula (1) are methyl groups. Excluding cases. Examples of the hydroxyalkyl group include lower hydroxyalkyl groups having 1 to 4 carbon atoms such as hydroxymethyl group, hydroxyethyl group, hydroxypropyl group and hydroxybutyl group.

  Specific examples of the organic quaternary ammonium hydroxide include tetramethyl ammonium hydroxide (sometimes abbreviated as "TMAH"), bis (2-hydroxyethyl) dimethyl ammonium hydroxide, and tetraethyl ammonium hydroxide. (Sometimes abbreviated as "TEAH"), tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, trimethyl (hydroxyethyl) ammonium hydroxide (common name: choline), triethyl (hydroxyethyl) ammonium hydroxide and the like. Be

Among the above-mentioned organic quaternary ammonium hydroxides, bis (2-hydroxyethyl) dimethylammonium hydroxide, trimethyl (hydroxy), for reasons such as washing effect, less metal residue, economy, washing liquid stability, etc. Particularly preferred are ethyl) ammonium hydroxide, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide and tetrabutyl ammonium hydroxide.
One of these organic quaternary ammonium hydroxides may be used alone, or two or more thereof may be used in combination in any ratio.

<Component (D): Water>
Component (E) water used in the cleaning solution of the present invention mainly plays a role as a solvent, and it is preferable to use deionized water or ultrapure water in which impurities are reduced as much as possible.

<Component (E): chelating agent>
In the cleaning agent of the present invention, in addition to the components (A) to (D) described above, preferably, a chelating agent other than the component (A) may be further contained as the component (E). However, the chelating agent (component (E)) of this invention excludes the compound shown by above-mentioned Formula (1).
The chelating agent dissolves and removes the insoluble metal complex of copper and copper contained in the metal wiring on the substrate surface, such as impurity metals such as tungsten and cobalt and the barrier slurry used in the CMP step. It has an action.

As the chelating agent, organic acids having the above-mentioned action, inorganic acids, amines and salts thereof or derivatives thereof may be used, and one type may be used alone, or two or more types may be used in an optional ratio. You may use together.
As component (E), it is particularly selected from the group consisting of oxalic acid, citric acid, tartaric acid, malic acid, picolinic acid, ethylenediamine, aminoethanol, ethylenediaminetetraacetic acid, ammonia, glycine, aspartic acid, iminodiacetic acid, alanine and β-alanine Or at least one selected from the group consisting of Moreover, these salts can also be used suitably.
Among these, at least one selected from the group consisting of oxalic acid, citric acid, tartaric acid, tartaric acid, picolinic acid, glycine and iminodiacetic acid is suitably used in view of the strength of the chelating effect, stability of quality and ease of availability. be able to.

<Component (F): surfactant>
In the cleaning agent of the present invention, in addition to the components (A) to (D) described above, a surfactant may be further contained as a component (F). Since the surface of the interlayer insulating film is hydrophobic, it is difficult to clean with a cleaning solution based on water. The surfactant of component (F) has an effect of improving the hydrophilicity of the hydrophobic substrate surface. By blending the surfactant to improve the affinity to the substrate surface, the action of the cleaning liquid can be exerted also between particles and the like present on the substrate, which can contribute to the removal of the residue. In the cleaning solution containing no surfactant, the cleaning effect is low due to the low affinity between the cleaning solution and the surface of the hydrophobic substrate.

There is no restriction | limiting in particular as surfactant of a component (F), Any of anionic surfactant, cationic surfactant, nonionic surfactant, and amphoteric surfactant can be used.
An example of the surfactant that can be suitably used in the cleaning solution of the present invention is an anionic surfactant. Examples of anionic surfactants include alkyl sulfonic acids and salts thereof, alkyl benzene sulfonic acids and salts thereof, alkyl diphenyl ether disulfonic acids and salts thereof, alkyl methyl taurate and salts thereof, and sulfosuccinic acid diesters and salts thereof. Particularly preferred sulfonic acid type anionic surfactants include dodecylbenzene sulfonic acid (sometimes abbreviated as "DBS"), dodecane sulfonic acid and alkali metal salts thereof. Among these, dodecylbenzenesulfonic acid and its alkali metal salt are preferably used from the viewpoint of quality stability and availability.

  Examples of other anionic surfactants include carboxylic acid type anionic surfactants. The carboxylic acid type anionic surfactant is an anionic surfactant containing a carboxyl group in the molecule, and among them, a compound represented by the following general formula (3) is preferable.

R ⁵ -O- (AO) _m- (CH ₂ ) _n -COOH (3)
In the above formula (3), R ⁵ is a linear or branched alkyl group, and has 8 to 15 carbon atoms, preferably 10 to 13 carbon atoms. AO is an oxyethylene group and / or an oxypropylene group, and m is 3 to 30, preferably 4 to 20, and more preferably 4.5 to 10. In addition, n is 1 to 6, preferably 1 to 3.

Specific examples of the carboxylic acid type anionic surfactant represented by the above general formula (3) include polyoxyethylene lauryl ether acetic acid, polyoxyethylene tridecyl ether acetic acid, polyoxyethylene alkyl ether acetic acid and the like. Can.
Surfactants, such as these anionic surfactant, may be used individually by 1 type, and may use 2 or more types together by arbitrary ratios.

  The surfactant may contain metal impurities such as Na, K, Fe and the like in an amount of 1 to several thousand mass ppm in a commercially available form, and in this case, the surfactant is a metal. It becomes a pollution source. Therefore, when the component (F) contains metal impurities, the component (F) is selected so that the content of each metal impurity is usually 10 ppm or less, preferably 1 ppm or less, more preferably 0.3 ppm or less. Is preferably purified and used. As this purification method, for example, a method of dissolving the component (F) in water and passing it through an ion exchange resin so as to capture metal impurities in the resin is preferable. By using the surfactant thus purified, it is possible to obtain a cleaning liquid having an extremely reduced metal impurity content.

<Component (G): reducing agent>
In addition to the above-mentioned components (A) to (D), the detergent of the present invention preferably further comprises a reducing agent as component (G). The reducing agent has the function of lowering the redox potential of the washing solution.
Among the reducing agents (G), preferred is ascorbic acid or a salt thereof and / or gallic acid or a salt thereof.

<Other ingredients>
The cleaning solution of the present invention may contain components other than the above components (A) to (G) at an arbitrary ratio as long as the performance thereof is not impaired.
As other ingredients, the following may be mentioned.
P-toluenesulfonic acid and its salts and naphthalenesulfonic acid and its salts, which store the effect of the component (B); benzotriazole, 3-aminotriazole, N (R ³ ) ₃ (R ³ is identical to or different from each other A nitrogen-containing organic compound such as an alkyl group having 1 to 4 carbon atoms and / or a hydroxyalkyl group having 1 to 4 carbon atoms such as urea and thiourea; a water-soluble polymer such as polyethylene glycol and polyvinyl alcohol; R ⁴ OH ( R ⁴ is an alkyl alcohol compound such as an alkyl group having 1 to ⁴ carbon atoms);
Dissolved gases such as hydrogen, argon, nitrogen, carbon dioxide, ammonia:
An etching accelerator that can be expected to have the effect of removing polymers firmly attached after dry etching such as hydrofluoric acid, ammonium fluoride and BHF (buffered hydrofluoric acid):
Oxidizers such as hydrogen peroxide, ozone, oxygen:
Moreover, components other than water, such as ethanol, may be included as a solvent.

<Method of producing cleaning solution>
The method for producing the cleaning solution of the present invention is not particularly limited and may be a conventionally known method. For example, the components of the cleaning solution (components (A) to (D), other components used as needed) are mixed It can be manufactured by doing. Usually, it is manufactured by adding component (A)-(C) and the other component used as needed to the solvent (D) water.

The order of mixing at that time is also arbitrary as long as there is no particular problem such as reaction or generation of precipitates, and any two or three or more components of the components of the cleaning solution are compounded in advance, and the remaining components are then added. May be mixed, or the components may be mixed at one time.
The cleaning solution of the present invention can also be manufactured by adjusting the concentration of each component so that the concentration is suitable for cleaning, but from the viewpoint of suppressing the cost during transportation and storage, the concentration of each component is high. It is often used after diluting it with water after producing the contained washing solution (hereinafter referred to as "washing stock solution").

As a suitable density | concentration range of the washing | cleaning liquid of component (A), 0.005-0.2 mass%, A more preferable range is 0.025-0.1 mass%. If this concentration exceeds 0.2% by mass, copper or barrier metal may be corroded, and if it is less than 0.005% by mass, there is a possibility that the insoluble precipitates derived from the slurry can not be removed.
Component (C) is 0.001 to 0.5 mass%.

Moreover, when it contains the component (E) in addition to the components (A) to (D), the preferable concentration range of the washing stock solution is 0.001 to 0.2 mass% (however, the concentration is higher than that of the component (BA) Is low).
Moreover, when it contains in addition to component (A)-(D) and contains component (F), as a suitable density | concentration range of washing | cleaning stock solution, it is 0.001-0.1 mass%.

Moreover, when it contains in addition to component (A)-(D) and contains component (G), as a suitable density | concentration range of washing | cleaning stock solution, it is 0.001-0.1 mass%.
The concentration of each component of the cleaning liquid when cleaning the semiconductor device substrate is appropriately determined according to the semiconductor device substrate to be cleaned.
The cleaning solution to be used for cleaning may be manufactured by diluting the undiluted cleaning solution so that the concentration of each component is appropriate to the substrate for semiconductor device to be cleaned, or it may be You may adjust and manufacture each component directly.

<Method of cleaning substrate for semiconductor device>
Next, the method for cleaning a substrate for a semiconductor device of the present invention (hereinafter sometimes referred to as “the cleaning method of the present invention”) will be described.
The cleaning method of the present invention is performed by a method in which the above-described cleaning liquid of the present invention is brought into direct contact with the substrate for a semiconductor device.

Examples of the substrate for semiconductor devices to be cleaned include various substrates for semiconductor devices such as semiconductors, glasses, metals, ceramics, resins, magnetic substances, and superconductors.
Among these, the cleaning liquid of the present invention can be effectively cleaned without causing corrosion to Cu wiring and barrier metal, and is particularly suitable for a substrate for a semiconductor device having a metal or a metal compound on the surface as a wiring or the like. In particular, it is suitable for a substrate for a semiconductor device having a Cu wiring on the surface.

  Here, W, Cu, Ta, Ti, Cr, Co, Zr, Hf, Mo, Ru, Au, Pt, Ag etc. are mentioned as said metal used for the substrate for semiconductor devices, As a metal compound, it is mentioned. And nitrides, oxides, and silicides of these metals. Among these, Cu, Ta, Ti, Co, Ru and compounds containing these are suitable cleaning targets. The cleaning method of the present invention is also suitable for a substrate for a semiconductor device having a low dielectric constant insulating material, because the cleaning method has a high cleaning effect even on a highly hydrophobic low dielectric constant insulating material.

  As such low dielectric constant materials, organic polymer materials such as Polyimide, BCB (Benzocyclobutene), Flare (Honeywell), SiLK (Dow Chemical), inorganic polymer materials such as FSG (Fluorinated silicate glass), BLACK DIAMOND (Fluorinated silicate glass) SiOC materials such as Applied Materials, Inc., Aurora (ASM, Japan) and the like can be mentioned.

Here, the cleaning method of the present invention is particularly suitably applied when the semiconductor device substrate has a Cu wiring and a barrier metal on the substrate surface and the substrate is cleaned after the CMP process.
In the CMP process, polishing is performed by rubbing the substrate against the pad using an abrasive.
The abrasive includes abrasive particles such as colloidal silica (SiO ₂ ), fumed silica (SiO ₂ ), alumina (Al ₂ O ₃ ), ceria (CeO ₂ ), and the like. Such abrasive particles are the main cause of particulate contamination of the substrate for semiconductor devices, but the cleaning solution of the present invention has the function of removing the particles adhering to the substrate to disperse in the cleaning solution and preventing reattachment. Show a high effect on the removal of particulate contamination.

In addition, the abrasive may contain additives other than the abrasive particles, such as an oxidizing agent and a dispersing agent. In particular, in CMP polishing of a semiconductor device substrate having a Cu film as a metal wiring on its surface, the Cu film is easily corroded, and therefore an anticorrosive is often added.
As the anticorrosive agent, an azole anticorrosive agent having a high anticorrosive effect is preferably used. More specifically, examples of the hetero atom containing a heterocycle in which the hetero atom is a nitrogen atom only include diazoles, triazoles, and tetrazoles. Examples of a hetero ring containing a nitrogen atom and an oxygen atom include oxazoles and iso. An oxazole type and an oxadiazole type are mentioned, As a thing containing the heterocyclic ring of a nitrogen atom and a sulfur atom, a thiazole type, an isothiazole type, and a thiadiazole type are mentioned. Among them, benzotriazole (BTA) -based anticorrosive agents having excellent anticorrosion effect are preferably used.

The cleaning solution of the present invention is excellent in that the contamination derived from the anticorrosive agent can be extremely effectively removed when it is applied to the substrate surface after being polished with an abrasive containing such an anticorrosive agent.
That is, when these anticorrosive agents are present in the polishing agent, they inhibit the corrosion of the Cu film surface, but react with the Cu ions eluted at the time of polishing to generate a large amount of insoluble precipitates. The cleaning solution of the present invention can efficiently dissolve and remove such insoluble precipitates, and can improve throughput.

Therefore, the cleaning method of the present invention is suitable for cleaning a substrate for a semiconductor device after CMP treatment of a surface where a Cu film and a barrier metal coexist, and in particular, the CMP treatment is performed with an abrasive containing an azole anticorrosive. It is suitable for cleaning of a substrate.
As described above, the cleaning method of the present invention is carried out by a method in which the cleaning liquid of the present invention is brought into direct contact with the semiconductor device substrate. A cleaning solution having a suitable component concentration is selected in accordance with the type of semiconductor device substrate to be cleaned.

  In the method of contacting the cleaning liquid to the substrate, a dip type in which the cleaning liquid is filled in the cleaning tank to immerse the substrate, a spin type in which the substrate is rotated at high speed while flowing the cleaning liquid from the nozzle onto the substrate, Spray type etc. are mentioned. As a device for performing such cleaning, there are a batch type cleaning device which simultaneously cleans a plurality of substrates contained in a cassette, and a single wafer type cleaning device which mounts one substrate on a holder and cleans. .

The cleaning solution of the present invention can be applied to any of the above-mentioned methods, but is preferably used for spin type or spray type cleaning because it can remove contaminants more efficiently in a short time. In this case, if it is applied to a single wafer type cleaning apparatus in which a reduction in cleaning time and a reduction in the amount of cleaning solution used is desired, these problems are preferably solved.
In the cleaning method of the present invention, when combined with physical cleaning methods, particularly scrub cleaning using a cleaning brush and ultrasonic cleaning with a frequency of 0.5 MHz or more, the removability of contamination by fine particles attached to the substrate It is preferable because it further improves and leads to shortening of the cleaning time. In particular, in cleaning after CMP, scrubbing is preferably performed using a resin brush. The material of the resin brush may be arbitrarily selected, but it is preferable to use, for example, PVA (polyvinyl alcohol) or PVF (polyvinyl formal) which is a modified product thereof.

Furthermore, water washing may be performed before and / or after the washing by the washing method of the present invention.
In the cleaning method of the present invention, the temperature of the cleaning solution may be usually room temperature, but may be heated to about 30 to 70 ° C. as long as the performance is not impaired.

  Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not changed.

Example 1
<Preparation of washing solution stock solution>
Component (A) 1% by mass of histidine as a compound represented by the formula (1), 8% by mass of tetraethylammonium as a component (B) imidazol compound as a component (B), and 0.01% by mass of imidazole as a component (C) pH adjuster Hydroxide (TEAH) and water of component (D) were mixed to prepare a stock solution of a substrate cleaning solution for a semiconductor device of Example 1 having the composition shown in Table 1. Subsequently, water was added to the washing solution stock solution to dilute the solution 40 times to prepare the washing solution of Example 1.

<PH measurement>
While stirring the cleaning solution of Example 1 using a magnetic stirrer, the pH was measured with a pH meter (trade name "D-24" manufactured by Horiba, Ltd.). The measurement sample was maintained at 25 ° C. in a thermostat bath. The measurement results are shown in Table 1.

<Measurement of Cu etch rate, Co etch rate (evaluation of corrosion resistance)>
A silicon substrate on which a Cu film is formed (or a silicon substrate on which a Co film is formed, BR> J is cut into 25 mm squares, and a film of the substrate is formed using a fluorescent X-ray analyzer (model: “RIX 3000” manufactured by Rigaku) Subsequently, the substrate was immersed in the cleaning liquid of Example 1 for a predetermined time at 25 ° C. The substrate after immersion was taken out, washed immediately with ultrapure water, and dried by air blow. The film thickness is again measured with a fluorescent X-ray analyzer under the same measurement conditions as the first measurement conditions, and the amount of film thickness (film thickness reduction amount) in which the Cu and Co substrates are dissolved is measured again. The rate [nm / min] and the Co etch rate [nm / min] were determined, and the results are shown in Table 1.

<Cu-BTA solubility measurement>
Copper acetate (II) (anhydrous) was dissolved in ultrapure water to prepare a 1.5% by mass aqueous solution (copper acetate aqueous solution). Subsequently, benzotriazole was dissolved in ultrapure water to prepare a 1.0 mass% aqueous solution (BTA aqueous solution). The aqueous solution of BTA was added twice as much to the aqueous solution of copper acetate, and stirred to prepare a 0.9% by mass aqueous solution of Cu-BTA. To 40 g of the washing solution, 100 μl of a Cu-BTA aqueous solution was added and stirred for 2 minutes, and the presence or absence of dissolution was visually confirmed. The aqueous 0.9% Cu-BTA solution was continued to be added until the unwanted matter came out. Cu-BTA solubility [mg / L] was determined from the amount of added solution.

<Washing evaluation>
Add 100 μg of 23.6% colloidal silica aqueous solution (扶桑 Chemistry PH-H10) to 80 g of 0.9 mass% Cu-BTA prepared by the above-mentioned Cu-BTA solubility measurement, and 2 mL on 200 mm Cu substrate after 200 rpm 10 seconds, 2000 rpm 10 seconds It was spin-coated. The substrate surface was cleaned using a single wafer cleaner. The number of defects was measured for the cleaned substrate using a surface inspection apparatus ("LS-6600" manufactured by Hitachi High-Tech Fielding Co., Ltd.). The results are shown in Table 1.

Example 2
In Example 1, the cleaning solution is prepared in the same manner as in Example 1 except that the amount of imidazole which is the component (B) azole compound contained in the stock solution of the substrate cleaning solution for semiconductor devices is changed to 0.5% by mass. Rate, Co etch rate, Cu-BTA solubility, wash experiments were performed. The results are shown in Table 1.

[Example 3]
In Example 1, the cleaning solution is prepared in the same manner as in Example 1 except that the amount of imidazole which is the component (B) azole compound contained in the stock solution of the substrate cleaning solution for semiconductor devices is changed to 1% by mass, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, cleaning experiments were performed. The results are shown in Table 1.

Example 4
In Example 1, 0.5 mass% of the amount of histidine which is the compound of the component (A) formula (1) contained in the stock solution of the substrate cleaning liquid for semiconductor devices, and the amount of the imidazole which is the component (B) azole compound A washing solution was prepared in the same manner as in the above except that the content was changed to 0.1% by mass, and pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and washing experiments were performed. Table the results-
Shown in 1.

[Example 5]
In Example 4, the cleaning solution is prepared in the same manner as in Example 4 except that the amount of imidazole which is the component (B) azole compound contained in the stock solution of the substrate cleaning solution for semiconductor devices is changed to 1% by mass, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, cleaning experiments were performed. The results are shown in Table 1.

[Example 6]
In Example 1, the amount of imidazole which is the component (B) azole compound contained in the stock solution of the substrate cleaning liquid for semiconductor devices is changed to 0.1% by mass, and further dodecylbenzenesulfonic acid as the component (F) surfactant The washing solutions were all prepared in the same manner as in the preparation of the stock solution by mixing 0.5 mass% of the solution, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and wash experiments were conducted. The results are shown in Table 1.

[Example 7]
In Example 6, 0.5 mass% of citric acid as a component (E) chelating agent is mixed instead of dodecylbenzenesulfonic acid as a component (F) surfactant contained in a stock solution of a substrate cleaning liquid for semiconductor devices, and the stock solution is prepared. A washing solution was prepared in the same manner as in the preparation except for pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and washing experiments. The results are shown in Table 1.

[Example 8]
In Example 1, the amount of imidazole which is the component (B) azole compound contained in the stock solution of the substrate cleaning liquid for semiconductor devices is changed to 0.2% by mass, and further dodecylbenzenesulfonic acid as the component (F) surfactant The cleaning solution is prepared in the same manner as in the preparation of the stock solution, except that 0.5% by mass of citric acid is mixed with 0.5% by mass of citric acid as the component (E) chelating agent, -BTA solubility, wash experiments were performed. The results are shown in Table 1.

[Example 9]
In Example 8, a cleaning solution is prepared in the same manner as in Example 8 except that 0.2% by mass of thiazole is mixed to prepare a stock solution as the component (B) azole compound contained in the stock solution of the substrate cleaning solution for semiconductor devices. , Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were performed. The results are shown in Table 1.

[Example 10]
In Example 8, a cleaning solution was prepared in the same manner as in Example 8 except that the stock solution was prepared by mixing 0.3% by mass of triazole as the component (B) azole compound contained in the stock solution of the semiconductor device substrate cleaning solution. , Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were performed. The results are shown in Table 1.

Comparative Example 1
Component (B): 0.1% by mass of imidazole as an azole compound, 8% by mass of tetraethylammonium hydroxide as a component (C) pH adjuster, and water of component (D) are shown in Table 2. A stock solution of the substrate cleaning liquid for semiconductor device of Comparative Example 1 of the composition was prepared. Subsequently, water was added to the stock solution of the washing solution and diluted 40 times to prepare a washing solution of Comparative Example 1.
Using the cleaning liquid of Comparative Example 1, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were conducted in the same manner as in Example 1. The results are shown in Table-2.

Comparative Example 2
In Comparative Example 1, as the component (B) azole compound, component (A) histidine is changed to 1% by mass instead of imidazole 0.1% by mass, and citric acid as component (E) chelating agent is further added 0. A washing solution was prepared in the same manner as in preparation of the stock solution by adding 5% by mass and mixing, and pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and wash experiments were conducted. The results are shown in Table-2.

Comparative Example 3
A cleaning solution is prepared in the same manner as in Example 7 except that the component (B) azole compound is changed to 5.00% by mass of imidazole, and pH, Cu etch rate, Co etch rate, Cu-BTA solubility, wash experiment Carried out. The results are shown in Table-2.

Comparative Example 4
8% by mass of ethylenediamine, 0.75% by mass of acetamidophenol, and 1% by mass of vanillin. Component (C) A substrate for a semiconductor device of Comparative Example 4 having a composition shown in Table 3 by mixing 2.75% by mass of tetramethylammonium hydroxide (TMAH) and water of the component (D) as a pH adjuster. A stock solution of the washing solution was prepared. Subsequently, water was added to the washing solution stock solution and diluted 25 times to prepare a washing solution of Comparative Example 4.
Using the cleaning liquid of Comparative Example 4, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were performed in the same manner as in Example 1. The results are shown in Table-3.

Comparative Example 5
Component (A) As an amine compound shown by Formula (1), 8 mass% of histidines, 0.75 mass% of acetamide phenols, and 1 mass% of vanillin. Component (C) A substrate for a semiconductor device of Comparative Example 5 having a composition shown in Table 3 by mixing 2.75% by mass of tetramethylammonium hydroxide (TMAH) and water of the component (D) as a pH adjuster. A stock solution of the washing solution was prepared. Subsequently, water was added to the washing solution stock solution to dilute the solution 25 times to prepare a washing solution of Comparative Example 5.
Using the cleaning liquid of Comparative Example 4, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were performed in the same manner as in Example 1. The results are shown in Table-3.

Comparative Example 6
8% by mass of ethylenediamine, 1% by mass of imidazole as component (B) azole compound, 2.75% by mass of tetramethylammonium hydroxide (TMAH) as component (C) pH adjuster, component (D) Water was mixed to prepare a stock solution of the substrate cleaning liquid for semiconductor devices of Comparative Example 6 having the composition shown in Table-3. Subsequently, water was added to the washing solution stock solution and diluted 25 times to prepare a washing solution of Comparative Example 6.
Using the cleaning liquid of Comparative Example 6, pH, Cu etch rate, Co etch rate, Cu-BTA solubility, and cleaning experiments were performed in the same manner as in Example 1. The results are shown in Table-3.

[Discussion]
Since Example 4 and Comparative Example 1 are compared, the cleaning liquid of Comparative Example 1 does not contain the amine compound represented by the component (A) general formula (1), so the Cu-BTA solubility is very low, and the result of the cleaning experiment is also obtained. I understand that it is bad.
When Example 7 and Comparative Example 2 are compared, it can be seen that since the cleaning liquid of Comparative Example 1 does not contain the component (B) azole compound, the Co etch rate is high and the corrosion inhibition of Co metal is not sufficient.

Moreover, when Example 7 and Comparative Example 3 are contrasted, since the washing | cleaning liquid of the comparative example 3 contains 2 mass% or more (5 mass%) of component (B) azole compounds, Co etch rate is high and corrosion suppression of Co metal is carried out. Is not enough.
Further, since the cleaning solution of Examples 1 to 10 has the same or lower Cu etch rate as that of the conventional cleaning solution, it has the ability to inhibit the corrosion of Cu substrate equal to or higher than that of the conventional cleaning solution. From the same or higher level, it can be understood that the organic residue removal performance equal to or higher than that of the conventional cleaning liquid is maintained. And since Co etching rate is 0.20 nm / min or less, it turns out that the corrosion control performance of the barrier metal of Co is high.

  From the above results, it is clear that, by using the cleaning liquid of the present invention, effective cleaning can be performed without causing corrosion on the Cu wiring and barrier metal, and the semiconductor device can be protected by corrosion prevention on the surface of the Cu wiring. It is clear that the excellent cleaning effect of the substrate is exhibited.

  The cleaning solution for a substrate for a semiconductor device of the present invention can be efficiently cleaned without causing corrosion on the surface of the substrate for a semiconductor device, and the present invention relates to a contaminated semiconductor in the manufacturing process of a semiconductor device or a display device. It is very useful industrially as a cleaning treatment technology for device substrates.

Claims (13)

It is a substrate cleaning fluid for semiconductor devices whose pH is 8 or more containing the following components (A) to (D), and the concentration of (B) in the cleaning fluid is 0.001 to 2 mass%. Substrate cleaning fluid.
(A) a compound represented by the following general formula (1)

(In the above formula (1), R ¹ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R ² represents a carboxyl group, a carbonyl group, a functional group having an ester bond, an alkyl group having 1 to 4 carbon atoms, or R ³ represents a hydrogen atom, an acetyl group, or an alkyl group having 1 to 4 carbon atoms.
(B) azole compound (C) pH adjuster (D) water   The substrate cleaning liquid for semiconductor devices according to claim 1, wherein the compound represented by the component (A), general formula (1), is histidine and derivatives thereof or salts thereof.   The component (B) azole compound is imidazole, N-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole, triazole, pyrazole, thiazole 3. The substrate cleaning liquid for semiconductor devices according to claim 1, which is at least one selected from the group consisting of oxazole and pyrrole. The component (C) pH adjuster comprises an inorganic alkali compound containing an alkali metal and / or an alkaline earth metal or an organic quaternary ammonium hydroxide represented by the following formula (2). The substrate washing | cleaning liquid for semiconductor devices of any one of 1-3.
_{^{(R) 4 N + OH -}} ··· (2)
(In the above formula (2), R represents a hydroxyl group, an alkoxy group, or an alkyl group which may be substituted with halogen, and all four Rs may be the same or different from each other.)   Furthermore, the component (E) chelating agent is included, The board | substrate washing | cleaning liquid for semiconductor devices of any one of the Claims 1-4 characterized by the above-mentioned.   Furthermore, component (F) surfactant is contained, The board | substrate washing | cleaning liquid for semiconductor devices of any one of the Claims 1-5 characterized by the above-mentioned. The compound (E) chelating agent is at least one selected from the group consisting of diaminopropane, oxalic acid, citric acid, tartaric acid, malic acid, picolinic acid, glycine and iminodiacetic acid. The substrate washing | cleaning liquid for semiconductor devices as described in 5 or 6.   The substrate cleaning liquid for a semiconductor device according to claim 5 or 6, wherein the component (F) surfactant is an anionic surfactant.   The anionic surfactant is selected from the group consisting of alkyl sulfonic acid and its salt, alkyl benzene sulfonic acid and its salt, alkyl diphenyl ether disulfonic acid and its salt, alkyl methyl taurate and its salt, and sulfosuccinic acid diester and its salt 9. The substrate cleaning liquid for semiconductor devices according to claim 8, which is at least one of the following.   Furthermore, the component (G) reducing agent is included, The board | substrate washing | cleaning liquid for semiconductor devices of any one of the Claims 1-9 characterized by the above-mentioned.   The substrate cleaner for a semiconductor device according to claim 10, wherein the component (G) reducing agent is ascorbic acid or a salt thereof and / or gallic acid or a salt thereof.   A method for cleaning a substrate for semiconductor device, comprising cleaning the substrate for semiconductor device using the cleaning liquid for substrate for semiconductor device according to any one of claims 1 to 11.   13. The cleaning of a substrate for a semiconductor device according to claim 12, wherein the substrate for a semiconductor device has a Cu wiring and a barrier metal on the surface of the substrate and is a substrate after chemical mechanical polishing. Method.