JP7735686B2 - Electroless copper plating composition and electroless copper plating method - Google Patents

Description

The present invention relates to a composition for electroless copper plating and an electroless copper plating method. The present invention also relates to a kit for use in the electroless copper plating method.

In recent years, with the trend toward smaller, lighter, and more sophisticated electronic devices, there has been a strong demand for finer and denser metal wiring in semiconductor elements. This demand for finer and denser wiring has led to narrower widths of the concave-convex patterns in which metal wiring is formed, and to increase the depth to ensure sufficient current density, the aspect ratio has been steadily increasing.
In a standard process, a seed layer made of a thin copper film is formed by sputtering on the inner walls of holes (vias) or grooves (trenches) in a concave-convex pattern for metal wiring formed on a semiconductor substrate, and then copper is filled and embedded into the vias or trenches by electroplating.
As the aspect ratio of the concave-convex pattern for metal wiring increases, copper plating films grown near the openings and on the sides of vias or trenches tend to come into contact with each other before the copper plating film at the bottom of the vias or trenches has fully grown. Contact between copper plating films results in the formation of voids and seams in the cross section of the wiring. The presence of voids and seams inside the metal wiring is undesirable because it leads to increased wiring resistance and reduced electromigration resistance.

Japanese Patent Application Laid-Open No. 2013-204107 Japanese Patent Application Publication No. 03-003296 Japanese Patent Application Laid-Open No. 2002-180259 Japanese Patent Application Laid-Open No. 2003-268558 Japanese Patent Application Laid-Open No. 2020-045558

Even when the concave-convex pattern for metal wiring has a high aspect ratio, it is preferable to be able to fill copper into vias or trenches while suppressing the occurrence of voids and seams, and to form metal wiring with good electrical properties.
Under these circumstances, the present inventors first attempted to perform electroless copper plating before electrolytic copper plating to achieve bottom-up via or trench formation in a concave-convex pattern. Electroless copper plating has the advantages of being able to form films at low temperatures, having good adhesion, and being able to form films even on complex patterns. Therefore, it is believed that the use of electroless copper plating can more efficiently form metal wiring.
However, even when electroless copper plating is used, if the plating grows at a uniform rate on the opening, side, and bottom of the inner wall of a via or trench, the opening is easily blocked, and voids and seams are likely to form. Therefore, the inventors attempted to solve the above problem by controlling the growth rate of the copper plating film on the bottom of the inner wall of a via or trench and the growth rate of the copper plating film on the opening and side in electroless copper plating.
Although various electrolytic or electroless copper plating solutions are known (e.g., Patent Documents 1 to 5), no attention has been paid to controlling the growth rate of the copper plating film at the opening, side and bottom of the inner wall of a via or trench in a concave-convex pattern of metal wiring in electroless copper plating.

The present invention relates to a composition for electroless copper plating, an electroless copper plating method, and a kit for use in the electroless copper plating method, which are shown below.
[1] A composition for electroless copper plating comprising a copper ion source, a complexing agent, a reducing agent, a pH adjuster, and water,
The electroless copper plating composition further comprises at least one member selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof.
[2] The optionally substituted 2-aminothiazole is represented by the formula:
[In the formula, ^R1 and ^R2 are each independently a hydrogen atom, a _C1 - _C6 alkyl group, a carboxyl group, a carboxy _C1 - _C6 alkyl group, a nitro group, a hydroxyl group, a _C1 - _C6 alkylamino group, a _C2 - _C7 carboxylic acid ester, or a halogen atom.]
The electroless copper plating composition according to [1] above, wherein the compound is one or more selected from the group consisting of compounds represented by the formula:
[3] Formula:
[In the formula, R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a C ₁ to C ₆ alkyl group, a mercapto group, or an amino group.]
The electroless copper plating composition according to [1] or [2] above, further comprising at least one nitrogen-containing heterocyclic compound selected from the group consisting of:
[4] The composition for electroless copper plating according to any one of [1] to [3] above, wherein the pH value is in the range of 11 to 14.
[5] The electroless copper plating composition according to any one of [1] to [4] above, wherein the complexing agent is at least one selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, and quadrol.
[6] The composition for electroless copper plating according to any one of [1] to [5] above, wherein the reducing agent is hydrazine.
[7] The composition for electroless copper plating according to any one of [1] to [6], wherein the pH adjuster is tetramethylammonium hydroxide.
[8] The electroless copper plating composition according to any one of [1] to [7] above, wherein the 2-aminothiazole which may have a substituent is at least one member selected from the group consisting of 2-aminothiazole, 2-amino-4-methylthiazole, 2-amino-5-methylthiazole, 2-aminothiazole-4-carboxylic acid, (2-amino-4-thiazolyl)acetic acid, and 2-amino-4,5-dimethylthiazole.
[9] The electroless copper plating composition according to any one of [3] to [8], wherein the nitrogen-containing heterocyclic compound is at least one selected from the group consisting of 1,2,4-triazole, 4-amino-1,2,4-triazole, 1H-benzotriazole, 3-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, 5-mercapto-1-methyltetrazole, 2-mercaptopyrimidine, and 4,6-dimethyl-2-mercaptopyrimidine.
[10] The composition for electroless copper plating according to any one of [1] to [9] above, further comprising a halide ion source.
[11] The electroless copper plating composition according to [10], wherein the halide ion source is hydrochloric acid.
[12] A step of contacting the electroless copper plating composition according to any one of [1] to [11] with a substrate;
and forming an electroless copper plating layer on the substrate.
[13] The electroless copper plating method according to [12], wherein the electroless copper plating layer is an electroless copper plating layer that will become copper wiring.
[14] The substrate has a via or a trench for forming an electroless copper plating layer,
[14] The electroless copper plating method according to [12] or [13], wherein the ratio of the maximum length in the depth direction to the minimum length of the opening in the via or trench (maximum length in the depth direction/shortest length of opening) is 2 or more.
[15] The electroless copper plating method according to any one of [12] to [14], wherein the substrate has a seed layer for forming an electroless copper plating layer, the seed layer being one or more types selected from the group consisting of a copper thin film, a cobalt thin film, and a ruthenium thin film.
[16] A kit for use in the electroless copper plating method according to any one of [12] to [15],
a first liquid containing at least one selected from the group consisting of a copper ion source, a complexing agent, a pH adjuster, 2-aminothiazole which may have a substituent and a salt thereof, and water, and further containing, as necessary, at least one selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and a halide ion source;
A kit comprising a reducing agent and a second liquid containing water, the second liquid being immiscible with each other.
[17] A kit for use in the electroless copper plating method according to any one of [12] to [15],
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water, and further containing, as necessary, at least one kind or more selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and at least one of a halide ion source;
The kit comprises a second liquid containing a reducing agent and water, and a third liquid containing one or more members selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water, which are not mixed with each other.
[18] A kit for use in the electroless copper plating method according to any one of [12] to [15],
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing at least one member selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; a fourth liquid containing at least one member selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), at least one of a halide ion source, and water;
in a mutually unmixed state.
[19] A kit for use in the electroless copper plating method according to any one of [12] to [15],
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing one or more compounds selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; and a fourth liquid containing one or more compounds selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and water.
A kit comprising a halide ion source and a fifth liquid comprising water, in a mutually immiscible state.

According to the present invention, in electroless copper plating, it is possible to control the growth rate of the copper plating film at the bottom of the inner wall of a via or trench and the growth rate of the copper plating film at the opening and side surfaces, thereby promoting the growth of the copper plating film at the bottom surface while suppressing the growth of the copper plating film at the opening and side surfaces. According to a preferred embodiment of the present invention, even when the uneven pattern of the metal wiring has a high aspect ratio, it is possible to suppress the occurrence of voids and seams and efficiently form metal wiring with excellent electrical properties.

1A to 1C are diagrams illustrating an example of steps in the electroless copper plating method of the present invention. 1 is a diagram schematically showing the growth amount of a copper plating film on the bottom, opening, and side surface of a via or trench in the electroless copper plating method of the present invention. FIG.

1. Electroless Copper Plating Composition The electroless copper plating composition of the present invention is a composition for electroless copper plating comprising a copper ion source, a complexing agent, a reducing agent, a pH adjuster, and water, and further comprising at least one additive selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof. The electroless copper plating composition of the present invention is suitably used to form a thin copper, cobalt, or ruthenium seed layer by sputtering or the like on the inner walls of vias or trenches in a concave-convex pattern for forming fine metal wiring on a substrate such as a semiconductor substrate, a semiconductor package substrate, or a printed circuit board, and then grow a copper plating film by electroless copper plating to fill the vias and trenches.

Each ingredient is explained below.

(a) Copper Ion Source The copper ion source used in the present invention is not particularly limited as long as it can supply copper(II) ions. For example, in addition to copper, copper salts such as copper sulfate, copper nitrate, copper acetate, cupric chloride, cupric bromide, cupric fluoride, cupric iodide, and ammonium copper sulfate are preferred. The copper salt may also be a hydrate. Among these, copper, copper sulfate, copper nitrate, and copper acetate are more preferred, with copper sulfate and copper nitrate being particularly preferred. Hydrates of copper sulfate and copper nitrate can also be suitably used. The copper ion source may be used alone or in combination of two or more.

The copper ion source is preferably contained in a range of 0.002 to 0.05 mol of copper ions per 1 kg of the electroless copper plating composition, more preferably 0.005 to 0.04 mol, and particularly preferably 0.006 to 0.03 mol. If the copper ion content is within the above range, plating can be performed stably and an appropriate plating speed can be obtained. When two or more copper ion sources are used, the total amount of those copper ions should be within the above range.

(b) Complexing Agent The complexing agent used in the present invention is used to complex copper ions so that they do not form salts and precipitate, thereby improving stability in the composition. The complexing agent used in the present invention is not particularly limited as long as it is one that is typically used in electroless copper plating. For example, aminocarboxylic acids, oxycarboxylic acids, and polycarboxylic acids are preferably used. Among these, aminocarboxylic acids are preferably used. The complexing agent may be used alone or in combination of two or more.

Aminocarboxylic acids include ethylenediaminetetraacetic acid (EDTA), hydroxyethylethylenediaminetriacetic acid (HEDTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (Quadrol), trans-1,3-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CyDTA), ethylenediaminetetrapropionic acid, nitrilotriacetic acid (NTA), and iminodiacetic acid (I). DA), iminodipropionic acid (IDP), hydroxyethyliminodiacetic acid, 1,3-propanediaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, glycol ether diaminetetraacetic acid, metaphenylenediaminetetraacetic acid, 1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid, diaminopropionic acid, glutamic acid, dicarboxymethylglutamic acid, ornithine, cysteine, N,N-bis(2-hydroxyethyl)glycine, (S,S)-ethylenediaminesuccinic acid, and salts thereof. Among these, one or more selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetramine-N,N,N',N'',N''',N'''-hexaacetic acid, and quadrol are preferred.

Examples of hydroxycarboxylic acids include citric acid, tartaric acid, malic acid, gluconic acid, glucoheptonic acid, glycolic acid, lactic acid, trihydroxybutyric acid, ascorbic acid, isocitric acid, tartronic acid, glyceric acid, hydroxybutyric acid, leucinic acid, citramalic acid, and salts thereof.

Examples of polycarboxylic acids include succinic acid, glutaric acid, malonic acid, adipic acid, oxalic acid, maleic acid, citraconic acid, itaconic acid, mesaconic acid, and salts thereof.

The content of the complexing agent is preferably at least 1 equivalent of the copper ion content, and more preferably at least 2 equivalents. Specifically, the complexing agent is preferably contained in a range of 0.002 to 0.5 mol per 1 kg of the electroless copper plating composition, more preferably 0.01 to 0.4 mol, and particularly preferably 0.05 to 0.3 mol. If the content of the complexing agent is within the above range, plating processing can be carried out stably. If two or more complexing agents are used, the total amount thereof should be within the above range.

(c) Reducing Agent The reducing agent used in the present invention is used to reduce copper ions. The reducing agent used in the present invention is not particularly limited as long as it is one that is typically used in electroless copper plating. Preferred examples include hydrazines, hydroxylamines, sodium sulfite, sodium bisulfite, formaldehyde, paraformaldehyde, formalin, glyoxylic acid, dimethylaminoborane, hypophosphorous acid, and salts thereof. The reducing agent may be used alone or in combination of two or more.

Examples of hydrazines include hydrazine, hydrazine carbonate, hydrazine sulfate, 1,1-diethylhydrazine, 1,2-diethylhydrazine, methylhydrazine, ethylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, 1,2-diisopropylhydrazine, hydrazine, cyclohexylhydrazine, allylhydrazine, and isopropylhydrazine. Among these, hydrazine, hydrazine carbonate, hydrazine sulfate, methylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, ethylhydrazine, 1,1-diethylhydrazine, and 1,2-diethylhydrazine are preferred. Hydrazine hydrates can also be suitably used.

Examples of hydroxylamines include hydroxylamine, hydroxylamine sulfate, O-methylhydroxylamine, O-ethylhydroxylamine, N-methylhydroxylamine, N,N-dimethylhydroxylamine, N,O-dimethylhydroxylamine, N-ethylhydroxylamine, N,N-diethylhydroxylamine, N,O-diethylhydroxylamine, O,N,N-trimethylhydroxylamine, N-(2-methoxyethyl)hydroxylamine, N-allylhydroxylamine, N,O-diallylhydroxylamine, and O-cyclohexyl-N,N-dimethylhydroxylamine. Of these, hydroxylamine, hydroxylamine sulfate, and N,N-diethylhydroxylamine are preferred.

The content of the reducing agent is preferably at least 1 equivalent of the copper ion content, and more preferably at least 2 equivalents. Specifically, the reducing agent is preferably contained in an amount ranging from 0.02 to 1 mol per 1 kg of the electroless copper plating composition, more preferably from 0.03 to 0.7 mol, and particularly preferably from 0.04 to 0.5 mol. If the content of the reducing agent is within the above range, plating processing can be carried out stably. If two or more reducing agents are used, the total amount of all reducing agents should be within the above range.

(d) pH Adjuster The pH adjuster used in the present invention is used to adjust the pH value of the electroless copper plating composition to an appropriate range. The pH adjuster used in the present invention is not particularly limited as long as it is one that is typically used in electroless copper plating. For example, alkali metal hydroxides, ammonia, amines, ammonium salts, phosphoric acid, nitric acid, sulfuric acid, etc. are preferably used. One pH adjuster may be used alone, or two or more pH adjusters may be used in combination.

The alkali metal hydroxide is not particularly limited as long as it is an alkali metal hydroxide, and examples include potassium hydroxide, sodium hydroxide, lithium hydroxide, and cesium hydroxide.

Amines are not particularly limited as long as they are compounds in which one to three hydrogen atoms of ammonia are substituted with organic groups. Examples include alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, diethylene glycolamine, 1-amino-2-propanol, and N-hydroxylethylpiperazine; and organic amines without hydroxyl groups such as ethylamine, benzylamine, diethylamine, n-butylamine, 3-methoxypropylamine, tert-butylamine, n-hexylamine, cyclohexylamine, n-octylamine, 2-ethylhexylamine, o-xylylenediamine, m-xylylenediamine, 1-methylbutylamine, ethylenediamine, 1,3-propanediamine, 2-aminobenzylamine, N-benzylethylenediamine, diethylenetriamine, and triethylenetetramine.

The ammonium salt is not particularly limited as long as it is a water-soluble quaternary ammonium salt. Examples include alkaline quaternary ammonium salts such as tetramethylammonium hydroxide (TMAH), ethyltrimethylammonium hydroxide, and tetraethylammonium hydroxide. Of these, tetramethylammonium hydroxide is preferably used.

Of these, preferred pH adjusters are potassium hydroxide, sodium hydroxide, lithium hydroxide, cesium hydroxide, triethylamine, ammonia, tetramethylammonium hydroxide, ethanolamine, and 1-amino-2-propanol, with tetramethylammonium hydroxide being particularly preferred.

In the present invention, the pH value of the electroless copper plating composition is preferably in the range of 11 to 14, more preferably in the range of 12 to 14, and even more preferably in the range of 12.5 to 13.5. The content of the pH adjuster may be determined appropriately depending on the content of other components so that the pH value of the electroless copper plating composition falls within the above range.

(e) Water The water used in the present invention is not particularly limited, but is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration, various adsorption treatments, etc., and pure water or ultrapure water is particularly preferred.

(f) Optionally Substituted 2-Aminothiazoles and Salts Thereof The electroless copper plating composition of the present invention further contains, as an additive, one or more selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof. According to a preferred embodiment of the present invention, the inclusion of one or more selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof can promote the growth of a copper plating film on the bottom of the inner wall of a via or trench when electroless copper plating is performed on a substrate such as a semiconductor substrate, semiconductor package substrate, or printed circuit board having a via or trench. That is, in the present invention, the optionally substituted 2-aminothiazoles and salts thereof can act as accelerators that improve the growth rate of a copper plating film on the bottom of the inner wall of a via or trench.
As a result of this effect, the growth rate of the copper plating film at the bottom of the inner wall of the via or trench becomes relatively faster, and the copper plating film at the bottom of the via or trench grows preferentially. This makes it possible to fill the via or trench with copper while suppressing the occurrence of voids and seams, thereby forming an electroless copper plating layer on the substrate that is free of voids and seams.

The optionally substituted 2-aminothiazole is not particularly limited as long as it has a 2-aminothiazole skeleton, but examples thereof include those represented by the formula:
[In the formula, ^R1 and ^R2 are each independently a hydrogen atom, a _C1 - _C6 alkyl group, a carboxyl group, a carboxy _C1 - _C6 alkyl group, a nitro group, a hydroxyl group, a _C1 - _C6 alkylamino group, a _C2 - _C7 carboxylic acid ester, or a halogen atom.]
It is preferable that the compound is one or more selected from the group consisting of compounds represented by the following formula:

In this specification, "C ₁ -C ₆ alkyl group" means an alkyl group having 1 to 6 carbon atoms. Examples of the C ₁ -C ₆ alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. Among these, a methyl group and an ethyl group are preferred as the C ₁ -C ₆ alkyl group.
Furthermore, "carboxy C ₁ -C ₆ alkyl group" means an alkyl group having 1 to 6 carbon atoms and a carboxyl group. Examples of the C ₁ -C ₆ alkyl group include the same as those described above. Specific examples of the carboxy C ₁ -C ₆ alkyl group are preferably a carboxymethyl group (-CH ₂ -COOH) or a carboxyethyl group (-CH ₂ CH ₂ -COOH).
The term "C ₁ -C ₆ alkylamino group" refers to an amino group having one or two C _{1 -C 6} alkyl groups. Examples of the C 1 -C ₆ alkyl group include the same as those described above. Specific examples of the C ₁ -C ₆ alkylamino group include a methylamino group and a dimethylamino group.
" _C2 - _C7 carboxylic acid ester" means a group represented by -COOR (R is a _C1 - _C6 alkyl group). Examples of the _C1 -C6 alkyl group include the same as those mentioned above. Specific examples of _{the C2} - _C7 carboxylic acid ester are preferably methyl carboxylate and ethyl carboxylate.
The "halogen atom" may be any of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a chlorine atom and a bromine atom being particularly preferred.

Among these, preferred examples include compounds in which, in formula (1), R ¹ and R ² are hydrogen atoms; compounds in which R ¹ is a C ₁ -C ₆ alkyl group and R ² is a hydrogen atom; compounds in which R ¹ is a hydrogen atom and R ² is a C ₁ -C ₆ alkyl group; compounds in which R ¹ is a carboxy group and R ² is a hydrogen atom; compounds in which R ¹ is a carboxy C ₁ -C ₆ alkyl group and R ² is a hydrogen atom; and compounds in which R ¹ and R ² are C _{1 -C 6} alkyl groups. Among these, one or _more compounds selected from the group consisting of compounds in which R ¹ is a C ₁ -C ₆ alkyl group and R ² is a hydrogen atom; compounds in which R ¹ is a carboxy C ₁ -C ₆ alkyl group and R ² is a hydrogen atom; and compounds in which R ¹ and R ² are C ₁ -C ₆ alkyl groups are more preferred, and particularly preferred is a compound in which R ¹ is a C 1 -C 6 alkyl group and R ² is a hydrogen atom.

Specific preferred examples of optionally substituted 2-aminothiazoles include 2-aminothiazole, 2-amino-4-methylthiazole, 2-amino-5-methylthiazole, 2-aminothiazole-4-carboxylic acid, (2-amino-4-thiazolyl)acetic acid, 2-amino-4,5-dimethylthiazole, 2-amino-5-nitrothiazole, 2-aminothiazole-4-ol, methyl 2-aminothiazole-4-carboxylate, methyl 2-aminothiazole-5-carboxylate, ethyl 2-aminothiazole-4-carboxylate, ethyl 2-aminothiazole-5-carboxylate, methyl 2-amino-4-methylthiazole-5-carboxylate, 5-fluorothiazol-2-amine, 5-chloro-1,3-thiazol-2-amine, 2-amino-5-bromo-1,3-thiazole, and 2-amino-4-bromo-1,3-thiazole. Among these, one or more selected from the group consisting of 2-aminothiazole, 2-amino-4-methylthiazole, 2-amino-5-methylthiazole, 2-aminothiazole-4-carboxylic acid, (2-amino-4-thiazolyl)acetic acid, and 2-amino-4,5-dimethylthiazole are more preferred, with one or more selected from the group consisting of 2-amino-4-methylthiazole, (2-amino-4-thiazolyl)acetic acid, and 2-amino-4,5-dimethylthiazole being particularly preferred, with 2-amino-4-methylthiazole being particularly preferred.

Specific examples of salts of the above compounds include hydrohalides, tetrafluoroborates, and hexafluorophosphates, of which hydrohalides are preferred, and hydrochlorides and hydrobromides are particularly preferred.
The optionally substituted 2-aminothiazoles or salts thereof may be used alone or in combination of two or more.

The electroless copper plating composition preferably contains one or more selected from the group consisting of optionally substituted 2-aminothiazoles and their salts in a range of 0.1 to 100 ppm by mass, more preferably 0.2 to 50 ppm, even more preferably 0.3 to 15 ppm, and particularly preferably 0.5 to 10 ppm. Within the above range, the ratio of the growth rate of the copper plating film at the bottom of the via or trench to the growth rate at the opening or side of the inner wall can be controlled within an appropriate range, depending on the aspect ratio of the via or trench and the length of the opening. This allows for stable via or trench filling while suppressing the occurrence of voids and seams, depending on the aspect ratio and opening length of the via or trench to be filled, and allows for more stable formation of an electroless copper plating layer on the substrate that is free of voids and seams. When two or more optionally substituted 2-aminothiazoles or salts thereof are used, the total amount of all of them should be within the above range.

(g) Nitrogen-Containing Heterocyclic Compound According to a preferred embodiment of the present invention, the electroless copper plating composition of the present invention contains, as an additive, a nitrogen-containing heterocyclic compound represented by the formula:
[In the formula, R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a C ₁ to C ₆ alkyl group, a mercapto group, or an amino group.]
The compound further contains at least one nitrogen-containing heterocyclic compound selected from the group consisting of:

According to a preferred embodiment of the present invention, the electroless copper plating composition of the present invention contains one or more nitrogen-containing heterocyclic compounds selected from the group consisting of an optionally substituted triazole represented by formula (2a) or formula (2b), an optionally substituted benzotriazole represented by formula (2c), an optionally substituted tetrazole represented by formula (2d), and an optionally substituted pyrimidine represented by formula (2e), thereby being able to suppress the growth of a copper plating film at the opening and sidewalls of a via or trench in a substrate such as a semiconductor substrate, a semiconductor package substrate, or a printed circuit board. That is, in the present invention, the nitrogen-containing heterocyclic compound can act as an inhibitor that suppresses the growth rate of a copper plating film at the opening and sidewalls of a via or trench.
As a result of this effect, the growth rate of the copper plating film at the bottom of the inner wall of the via or trench becomes relatively faster, and the copper plating film at the bottom of the via or trench grows preferentially. This makes it possible to fill the via or trench with copper while suppressing the occurrence of voids and seams, thereby forming an electroless copper plating layer on the substrate that is free of voids and seams.
Furthermore, by combining these nitrogen-containing heterocyclic compounds with one or more selected from the group consisting of 2-aminothiazoles and salts thereof, which may have a substituent that has the effect of promoting the growth of a copper plating film at the bottom of the inner wall of a via or trench, it is possible to more efficiently and stably increase the relative growth rate of the copper plating film at the bottom of the inner wall of a via or trench relative to the growth rate of the copper plating film at the opening and side of the inner wall of the via or trench.This makes it possible to more efficiently fill the via or trench while suppressing the occurrence of voids and seams, and to efficiently and stably form an electroless copper plating layer free of voids and seams on a substrate.

The optionally substituted triazole represented by formula (2a) is preferably 1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, or the like.
The optionally substituted triazole represented by formula (2b) is preferably 4-amino-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, or the like.
The optionally substituted benzotriazole represented by formula (2c) is preferably 1H-benzotriazole, 5-methyl-1H-benzotriazole, 5-chlorobenzotriazole, or the like.
The optionally substituted tetrazole represented by formula (2d) is preferably 5-mercapto-1-methyltetrazole.
As the pyrimidine represented by formula (2e) which may have a substituent, 2-mercaptopyrimidine, 4,6-dimethyl-2-mercaptopyrimidine, etc. are preferred.

Of these, 1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, and 1H-benzotriazole are more preferred.

When the electroless copper plating composition of the present invention contains a nitrogen-containing heterocyclic compound, the nitrogen-containing heterocyclic compound is preferably contained in the electroless copper plating composition in a range of 0.05 to 100 ppm by mass, more preferably 0.1 to 50 ppm, even more preferably 0.2 to 15 ppm, and particularly preferably 0.5 to 10 ppm. Within the above range, the growth rate of the copper plating film at the opening and side of the inner wall of the via or trench can be suppressed, and can be controlled to an appropriate range depending on the aspect ratio of the via or trench and the length of the opening. This allows for stable filling of the via or trench while suppressing the occurrence of voids and seams, depending on the aspect ratio and length of the opening of the via or trench to be filled, and allows for more stable formation of an electroless copper plating layer on the substrate that is free of voids and seams. When two or more of the above nitrogen-containing heterocyclic compounds are used, the total amount of all of them should be within the above range.

(h) Halide Ion Source The electroless copper plating composition of the present invention may further contain a halide ion source as an additive.
As the halide ion source, a fluoride ion source, a chloride ion source, a bromide ion source, or an iodide ion source is preferred, a chloride ion source or a bromide ion source is more preferred, and a chloride ion source is particularly preferred.
Specific examples of halide ion sources include acids such as hydrochloric acid and hydrobromic acid, and salts such as sodium chloride, ammonium chloride, calcium chloride, potassium chloride, potassium bromide, sodium fluoride, potassium iodide, cupric chloride, and cupric bromide. Among these, hydrochloric acid is preferred.
For example, cupric chloride and cupric bromide can be used as a source of both halide ions and copper ions.
The halide ion source may be used alone or in combination of two or more.

When the electroless copper plating composition of the present invention contains a halide ion source, the halide ion source is preferably contained in the electroless copper plating composition in an amount of 0.1 to 1000 ppm by mass, more preferably 0.2 to 500 ppm, and particularly preferably 0.5 to 100 ppm. Within the above range, the growth rate of the copper plating film on the bottom of the inner wall of a via or trench can be further improved. When two or more halide ion sources are used, the total amount thereof should be within the above range.

(i) Other Components In addition to the components described above, the electroless copper plating composition of the present invention may contain any additives that are commonly used in electroless copper plating compositions, provided that the effects of the present invention are not impaired.
Examples include surfactants such as alkyl sulfates, alkyl phosphates, and alkyl sulfonates; water-soluble polymers such as polyethylene glycol, polypropylene glycol, polyvinylpyrrolidone, polyamines, and polyvinyl alcohol; stabilizers such as 2,2'-bipyridyl, 4,4'-bipyridyl, and phenanthroline; and metal salts such as nickel sulfate and cobalt sulfate.
These additives function as levelers that improve the smoothness of electroless copper plating films. When the electroless copper plating composition of the present invention contains these additives, the content of these additives is preferably 1 ppm to 5000 ppm (by mass).

The electroless copper plating composition of the present invention can be produced by uniformly mixing the above-mentioned components.

2. Electroless Copper Plating Method The electroless copper plating method of the present invention comprises:
contacting the electroless copper plating composition with a substrate;
and forming an electroless copper plating layer on the substrate.

The electroless copper plating method of the present invention will be described below with reference to illustrative figures, but the electroless copper plating method of the present invention is not limited to these. Figure 1 is a diagram illustrating an example of the steps of the electroless copper plating method of the present invention. Figure 1 schematically illustrates only the structures necessary to explain the steps of the electroless copper plating method of the present invention.

First, as shown in FIG. 1(a), a substrate 100 is prepared. The substrate 100 preferably has a via or trench for forming an electroless copper plating layer. The substrate 100 with a via or trench can be manufactured, for example, by forming an interlayer insulating film 20 on a silicon substrate 10 and then forming a via or trench in the interlayer insulating film 20 by dry etching or other methods. A barrier metal layer 30, such as a tantalum layer, a tantalum nitride layer, a titanium layer, or a titanium nitride layer, may be formed on the surface of the interlayer insulating film 20, including the inner walls of the via or trench. It is preferable that a seed layer 40 made of a thin copper film is formed on the barrier metal layer 30 by chemical vapor deposition (CVD) or sputtering or other methods. The seed layer 40 may also be made of a thin cobalt or ruthenium film.

Next, the electroless copper plating composition of the present invention described above is brought into contact with the substrate 100, thereby forming an electroless copper plating layer 50 on the surface of the seed layer 40 on the inner wall of the via or trench, as shown in FIG. 1(b), thereby filling at least a portion of the via or trench. At this time, the entire via or trench may be filled with the electroless copper plating layer 50.

The electroless copper plating composition used in the electroless copper plating method of the present invention is as described above in "1. Electroless Copper Plating Composition," so the description will not be repeated here.

The electroless copper plating method of the present invention is not particularly limited as long as the electroless copper plating composition of the present invention contacts the inner wall of the via or trench in the substrate 100, and may be either a batch method in which multiple substrates are processed at once, or a single-wafer method in which one substrate is processed at a time.
The temperature during plating treatment is not particularly limited, but is preferably 40° C. to 90° C., more preferably 40° C. to 80° C., and even more preferably 50° C. to 75° C. The treatment time is not particularly limited as long as the desired plating growth amount is obtained, but is usually 0.5 to 20 minutes, preferably 1 to 15 minutes, and more preferably 2 to 10 minutes.
The pH value during plating is preferably in the range of 11 to 14, more preferably in the range of 12 to 14, and even more preferably in the range of 12.5 to 13.5.

In the electroless copper plating method of the present invention, the ratio of the maximum depth length (h) to the minimum length (d) of the opening of a via or trench in the substrate 100 prior to electroless copper plating (maximum depth length (h)/minimum opening length (d): sometimes referred to herein as the aspect ratio) is preferably 2 or greater, more preferably 3 or greater, even more preferably 5 or greater, and particularly preferably 7 or greater. The minimum opening length (d) is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, and particularly preferably 30 nm or less. The lower limit of the minimum opening length (d) is not particularly limited, but is preferably 1 nm or greater.

According to a preferred embodiment of the present invention, the electroless copper plating composition of the present invention can be used to form an electroless copper plating layer in a via or trench. Even when the via or trench has a high aspect ratio as described above, the via or trench can be filled with copper while suppressing the occurrence of voids and seams, achieving a bottom-up plating process. The electroless copper plating layer formed in this manner constitutes at least a portion of the copper wiring. The electroless copper plating composition of the present invention may also be used to completely fill the via or trench with copper. In this case, the electroless copper plating layer formed in the via or trench constitutes the copper wiring.

After the electroless copper plating layer is formed, electrolytic copper plating may be performed as needed to form an electrolytic copper plating layer 60, completely filling the via or trench (see FIG. 1(c)). In this case, the electroless copper plating layer and the electrolytic copper plating layer formed in the via or trench constitute the copper wiring. The electrolytic copper plating composition and processing conditions used for the electrolytic copper plating may be those known in the art and are not particularly limited. For example, the electrolytic copper plating composition and processing conditions described in International Publication No. 2007/096390 (Japanese Patent No. 5546215) may be referenced.
Furthermore, if necessary, excess electrolytic copper plating layer 60 or electroless copper plating layer 50, barrier metal layer 30, and seed layer 40 can be removed by performing CMP (chemical mechanical polishing) or the like, thereby forming copper wiring including electroless copper plating layer 50 and, if necessary, electrolytic copper plating layer 60 on substrate 100 (see FIG. 1(d)).

As mentioned above, electroless copper plating is generally known to have the advantages of being able to form films at low temperatures, having good adhesion, and being able to form films even on complex patterns. According to a preferred embodiment of the present invention, the electroless copper plating method of the present invention performs electroless copper plating using the electroless copper plating composition of the present invention, thereby achieving bottom-up via or trench formation while suppressing the occurrence of voids and seams, and utilizing the advantages of electroless copper plating to more efficiently form copper wiring on a substrate.

In the electroless copper plating method of the present invention, in order to suppress the occurrence of voids and seams, it is preferable to increase the growth rate of the copper plating film on the bottom of the via or trench, and it is even more preferable to suppress the growth rate of the copper plating film on the opening and side surfaces and relatively increase the growth rate of the copper plating film on the bottom surface.

According to a preferred embodiment of the present invention, when the ratio of the growth rates of the copper plating film at the bottom and opening of a via or trench satisfies the following relationship, even if the via or trench has a high aspect ratio, it is possible to fill the via or trench with copper while effectively suppressing the occurrence of voids and seams.
That is, the ratio (B/T) of the amount of copper plating film grown on the bottom surface (B) to the amount of copper plating film grown on the openings (T) in a certain time period is preferably large, more preferably at least 3, even more preferably at least 4, and particularly preferably at least 7. It is preferable that B/T is 30 or less.

Furthermore, according to a further preferred embodiment of the present invention, when the ratio of the growth rates of the copper plating film on the bottom and side surfaces of a via or trench satisfies the following relationship, even if the via or trench has a high aspect ratio and a narrow wiring width, it is possible to fill the via or trench with copper while effectively suppressing the occurrence of voids and seams.
That is, the ratio (B/S) of the amount of copper plating film grown on the bottom surface (B) to the amount of copper plating film grown on the side surface (S) in a certain period of time is preferably large, more preferably at least 5, even more preferably at least 8, and particularly preferably at least 9. It is preferable that B/S is 30 or less.

Figure 2 is a diagram schematically illustrating the amount of copper plating film grown on the bottom, opening, and side of a via or trench in the electroless copper plating method of the present invention. In this specification, the amount of copper plating film grown on the bottom of a via or trench (B), the amount of copper plating film grown on the opening (T), and the amount of copper plating film grown on the side (S) can be determined by measuring the lengths of the portions shown in Figure 2(a) in SEM photographs of the cross section of the via or trench before and after plating and calculating the difference between the lengths. Figure 2(b) shows that the amount of copper plating film grown on the opening (T) is suppressed, while the amount of copper plating film grown on the bottom (B) is relatively increased, resulting in bottom-up growth of the via or trench.

Substrates on which fine metal wiring can be formed using the electroless copper plating method of the present invention are not particularly limited, but examples include semiconductor substrates, semiconductor package substrates, printed circuit boards, and other substrates.

3. Electroless Copper Plating Composition Kit The electroless copper plating composition kit of the present invention is a kit for use in the electroless copper plating method of the present invention, comprising:
a first liquid containing at least one selected from the group consisting of a copper ion source, a complexing agent, a pH adjuster, 2-aminothiazole which may have a substituent and a salt thereof, and water, and further containing, as necessary, at least one selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and a halide ion source;
The reducing agent and the second liquid containing water are contained in a mutually immiscible state.
Alternatively, in another embodiment of the kit for electroless copper plating of the present invention,
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water, and further containing, as necessary, at least one nitrogen-containing heterocyclic compound selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and at least one halide ion source;
The composition may contain a second liquid containing a reducing agent and water, and a third liquid containing one or more members selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water, which are not mixed with each other.
In another embodiment of the electroless copper plating composition kit of the present invention,
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing at least one member selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; a fourth liquid containing at least one member selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), at least one of a halide ion source, and water;
may be present in an unmixed state.
In another embodiment of the electroless copper plating composition kit of the present invention,
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing one or more compounds selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; and a fourth liquid containing one or more compounds selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and water.
The fifth liquid may contain a halide ion source and water in a mutually unmixed state.

In each embodiment of the kit of the present invention, the solutions can be mixed at the time of use to be used in the electroless copper plating method of the present invention. Furthermore, it is preferable that, at the time of mixing, a pH adjuster is further added, if necessary, to adjust the pH to a desired range.
The copper ion source, complexing agent, pH adjuster, optionally substituted 2-aminothiazole and salts thereof, nitrogen-containing heterocyclic compound represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), halide ion source, and reducing agent are as described above in "1. Composition for electroless copper plating."
In each embodiment of the above kit, the amount of each component used may be within the range described above in "1. Composition for electroless copper plating" as the content in the composition for electroless copper plating obtained by mixing the respective solutions.
In each embodiment of the kit, each solution may further contain optional components as necessary, such as the additives exemplified in (i) Other Components in "1. Composition for Electroless Copper Plating" above.

Next, the present invention will be explained in more detail using examples and comparative examples, but the present invention is not limited to these examples in any way.

Examples 1 to 24
(1) Preparation of Electroless Copper Plating Composition Basic composition (1. Pure water (687.48 g per 1 kg of electroless copper plating composition), 2. 0.32% by mass of copper sulfate pentahydrate (3.20 g per 1 kg of electroless copper plating composition), 3. 5.1% by mass of diethylenetriaminepentaacetic acid (51.0 g per 1 kg of electroless copper plating composition), 4. 6.1% by mass of tetramethylammonium hydroxide (244.0 g of a 25% by mass aqueous solution of tetramethylammonium hydroxide per 1 kg of electroless copper plating composition), 5. 0.002% by mass of 2,2-bipyridyl (electroless copper plating composition) 6. 1.4 mass% hydrazine monohydrate (prepared by adding 14.3 g of 98 mass% hydrazine monohydrate per kg of electroless copper plating composition) was mixed in this order and stirred to form a homogeneous mixture, and then the components (components (f), (g), and (h)) were mixed in the compositional ratios shown in Table 1 with 1.4 mass% hydrazine monohydrate (prepared by adding 14.3 g of 98 mass% hydrazine monohydrate per kg of electroless copper plating composition) and stirred to form a homogeneous mixture, and the pH was adjusted to 12.8 using tetramethylammonium hydroxide as a pH adjuster to prepare a composition for electroless copper plating.

(2) Evaluation Sample of Electroless Copper Plating Composition and Electroless Copper Plating Process As an evaluation sample of the electroless copper plating composition, a silicon wafer was prepared by forming a via using a dry etching technique, and then depositing a tantalum barrier layer and a copper seed layer. After depositing the barrier layer and the seed layer, the ratio of the maximum depth (h) of the via to the minimum opening length (d) was 7.7. The via width was 45 nm.
The evaluation sample was immersed in the electroless copper plating composition prepared in (1) above at a treatment temperature of 65° C. for 5 minutes to perform electroless copper plating. The evaluation sample was then removed from the electroless copper plating composition and washed by immersion in ultrapure water for 10 seconds. The evaluation sample was then removed from the ultrapure water and dried with nitrogen blow.

(3) Calculation of plating growth amount The evaluation sample before and after the electroless copper plating treatment was cut in a direction perpendicular to the via to obtain smooth cross sections (cross sections of the via) of the evaluation sample before and after the treatment.
Next, the cross section of the via of the obtained evaluation sample was observed with an SEM ("SU9000" manufactured by Hitachi High-Tech Corporation), and the plating growth amount (B) at the bottom of the via, the plating growth amount (T) at the opening, and the plating growth amount (S) at the side were measured and each plating growth amount was calculated. The ratio of the plating growth amount (B) at the bottom to the plating growth amount (T) at the opening (B/T ratio) and the ratio of the plating growth amount (B) to the plating growth amount (S) at the side (B/S ratio) were calculated. A B/T ratio of 3 or more was considered acceptable. A B/S of 5 or more is also preferable.

Comparative Examples 1 to 3
Electroless copper plating compositions were prepared in the same manner as in Examples, except that the composition ratios were as shown in Table 1, and electroless copper plating treatment was carried out using evaluation samples. Each plating growth amount was calculated in the same manner as in Examples.

The results are shown in Table 1.

(4) Confirmation of the Presence of Voids and Seams The presence or absence of voids and seams was confirmed for some of the electroless copper plating compositions prepared in (1) above, according to the following procedure.
As a sample for evaluating the electroless copper plating composition, a silicon wafer was used in which a via was formed by dry etching, and a tantalum barrier layer and a copper seed layer were formed. After the barrier layer and seed layer were formed, the maximum depth (h)/minimum opening length (d) was 7.7. The via width was 45 nm.
The evaluation sample was immersed in the electroless copper plating composition prepared in (1) above at a treatment temperature of 65° C. for 10 minutes to perform electroless copper plating. The evaluation sample was then removed from the electroless copper plating composition and washed by immersion in ultrapure water for 10 seconds. The evaluation sample was then removed from the ultrapure water and dried with nitrogen blow.
The evaluation sample before and after the electroless copper plating treatment was cut in a direction perpendicular to the via to obtain smooth cross sections (cross sections of the via) of the evaluation sample before and after the treatment.
Next, the cross section of the via of the obtained evaluation sample was observed with an SEM ("SU9000" manufactured by Hitachi High-Technologies Corporation) and photographed at a magnification of 200,000 to check for the occurrence of voids and seams in the via.
The presence or absence of voids and seams in each of the 10 vias was checked, and a via with no voids or seams in 7 or more of the 10 was judged to be acceptable.

The results are shown in Table 2.

As shown by the above results, electroless copper plating using the electroless copper plating composition of the present invention promotes plating growth on the bottom of vias and suppresses plating growth on the openings and side surfaces. It is believed that similar results can be obtained for trenches, which, like vias, have a high aspect ratio in their uneven pattern. According to the present invention, plating growth on the bottom surfaces takes precedence over plating growth on the openings and side surfaces, thereby suppressing the occurrence of voids and seams.

10 Silicon substrate 20 Interlayer insulating film 30 Barrier metal layer 40 Seed layer 50 Electroless copper plating layer 60 Electrolytic copper plating layer 100 Substrate

Claims (18)

A composition for electroless copper plating comprising a copper ion source, a complexing agent, a reducing agent, a pH adjuster, and water,
further comprising at least one member selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof;
The optionally substituted 2-aminothiazole is represented by the formula:
[In the formula, ^R1 and ^R2 are each independently a hydrogen atom, a _C1 - _C6 alkyl group, a carboxyl group, a carboxy _C1 - _C6 alkyl group, a nitro group, a hydroxyl group, a _C1 - _C6 alkylamino group, a _C2 - _C7 carboxylic acid ester, or a halogen atom (excluding the case where ^R1 and ^R2 are hydrogen atoms).]
The composition for electroless copper plating comprises one or more compounds selected from the group consisting of compounds represented by the formula: The electroless copper plating composition according to claim 1, wherein the optionally substituted 2-aminothiazole is one or more selected from the group consisting of 2-amino-4-methylthiazole, 2-amino-5-methylthiazole, 2-aminothiazole-4-carboxylic acid, (2-amino-4-thiazolyl)acetic acid, and 2-amino-4,5-dimethylthiazole. formula:
[In the formula, R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are each independently a hydrogen atom, a C ₁ to C ₆ alkyl group, a mercapto group, or an amino group.]
3. The electroless copper plating composition according to claim 1, further comprising at least one nitrogen-containing heterocyclic compound selected from the group consisting of: 4. The electroless copper plating composition according to claim 3, wherein the nitrogen-containing heterocyclic compound is at least one selected from the group consisting of 1,2,4-triazole, 4-amino-1,2,4-triazole, 1H-benzotriazole, 3-mercapto-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, 5-mercapto-1-methyltetrazole, 2-mercaptopyrimidine, and 4,6-dimethyl-2-mercaptopyrimidine. 5. The electroless copper plating composition according to claim 1, wherein the pH value is in the range of 11 to 14 . 6. The electroless copper plating composition according to claim 1, wherein the complexing agent is at least one selected from the group consisting of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetramine-N,N,N',N'',N''',N' ' '-hexaacetic acid, and quadrol. 7. The electroless copper plating composition according to claim 1, wherein the reducing agent is hydrazine. 8. The electroless copper plating composition according to claim 1, wherein the pH adjuster is tetramethylammonium hydroxide. The electroless copper plating composition according to any one of claims 1 to 8, further comprising a halide ion source. The electroless copper plating composition according to claim 9, wherein the halide ion source is hydrochloric acid. contacting a substrate with the electroless copper plating composition of claim 1;
and forming an electroless copper plating layer on the substrate. The electroless copper plating method according to claim 11, wherein the electroless copper plating layer is an electroless copper plating layer that will become copper wiring. the substrate has a via or trench for forming an electroless copper plating layer;
13. The electroless copper plating method according to claim 11, wherein the ratio of the maximum depth length to the minimum length of the opening in the via or trench (maximum depth length/minimum opening length) is 2 or more. The electroless copper plating method according to any one of claims 11 to 13, wherein the substrate has a seed layer for forming an electroless copper plating layer, the seed layer being one or more types selected from the group consisting of a copper thin film, a cobalt thin film, and a ruthenium thin film. A kit for use in the electroless copper plating method according to any one of claims 11 to 14, comprising:
a first liquid containing at least one selected from the group consisting of a copper ion source, a complexing agent, a pH adjuster, 2-aminothiazole which may have a substituent and a salt thereof, and water, and further containing, as necessary, at least one selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and a halide ion source;
A kit comprising a reducing agent and a second liquid containing water, the second liquid being immiscible with each other. A kit for use in the electroless copper plating method according to any one of claims 11 to 14, comprising:
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water, and further containing, as necessary, at least one kind or more selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and at least one of a halide ion source;
The kit comprises a second liquid containing a reducing agent and water, and a third liquid containing one or more members selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water, which are not mixed with each other. A kit for use in the electroless copper plating method according to any one of claims 11 to 14, comprising:
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing at least one member selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; a fourth liquid containing at least one member selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), at least one of a halide ion source, and water;
in a mutually unmixed state. A kit for use in the electroless copper plating method according to any one of claims 11 to 14, comprising:
a first liquid containing a copper ion source, a complexing agent, a pH adjuster, and water;
a second liquid containing a reducing agent and water; a third liquid containing one or more compounds selected from the group consisting of optionally substituted 2-aminothiazoles and salts thereof, and water; and a fourth liquid containing one or more compounds selected from the group consisting of nitrogen-containing heterocyclic compounds represented by any one of formulas (2a), (2b), (2c), (2d), and (2e), and water.
A kit comprising a halide ion source and a fifth liquid comprising water, in a mutually immiscible state.