JP2022003170A - Composition for forming metal film and method of forming metal film - Google Patents

Abstract

To provide a composition for forming a metal film capable of forming a metal film having an excellent adhesion to a substrate, and a method of forming the metal film.SOLUTION: A composition for forming a metal film includes a metal complex that is exemplary expressed by a structural formula below, a counter anion of the metal complex, and a solvent of the metal complex, the counter anion of the metal complex including a same metal atom as that included in the metal complex. (M3 represents Cu, Ni, Mn, or Co in the equation.)SELECTED DRAWING: None

Description

The present disclosure relates to a composition for forming a metal film and a method for forming a metal film.

A metal film or a metal oxide film having excellent electrical conductivity and thermal conductivity is used for various purposes. The metal film or the like can be made into a film having light transmission by reducing the thickness.
For example, a copper film having high electrical conductivity and antibacterial properties is useful for forming a conductive layer, an electromagnetic wave shield, an antibacterial member, and the like on the surface of a base material. Further, the metal film has good thermal conductivity, and can be used as a heat radiating member, for example, in lighting equipment or the like.
A metal film or a metal oxide film, particularly a metal thin film having a thickness of micron order or nano order, is generally formed by a vapor phase method. However, since a gas phase method such as sputtering uses a large-scale device for film formation, various methods for forming a metal film by a wet method have been studied.
Examples of the commonly used wet method for forming a metal film include an electrolytic plating method, an electroless plating method, and the like, and any of these methods can form a metal film having a thickness on the order of microns.

However, in the electrolytic plating method, since a metal film is formed by using a base material as an electrode, the electric conductivity of the base material is indispensable, and it is difficult to apply it to a base material of an inorganic material such as a glass substrate.
According to the electroless plating method, a metal film can be deposited on a base material of an inorganic material, but the electroless plating solution contains a reducing agent, a catalyst and the like in addition to the metal material. Palladium chloride, tin chloride, etc. contained as a catalyst in the electroless plating solution may cause deterioration or modification of the metal film when mixed with the formed metal film.

As another method for forming a metal film, a method using a metal nanoparticle paste containing metal nanoparticles is known. However, the metal film formed by using the metal nanoparticle paste has insufficient adhesive force with the substrate due to the presence of voids between the particles, and has a desired volumetric resistance due to the voids between the particles. Problems such as unachievable may occur.

As a method for forming a metal thin film on a substrate, a method for forming a metal film using a gel containing an amorphous compound in which a hydroxyl group is bonded to a copper element and an organic solvent has been proposed (for example, JP-A-2015-158007). See Gazette).
Also, using a solution of a metal complex containing an organic group bonded to a metal with a carbon anion and a Lewis basic functional group, a nitrate ion, a nitrite ion, a halide ion or a hydroxide ion, a metal oxide or a metal is used. A technique capable of easily producing a thin film containing a sulfide has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2015-151358).

However, in the technique described in JP-A-2015-158007, an electrolytic reaction solution containing a metal ion is a precursor of metal fine particles in a specific pH range in the presence of a ligand that coordinates the metal ion. The process is complicated, such as precipitating an amorphous compound, recovering the obtained amorphous compound alone, and further adding an organic solvent to prepare an amorphous compound gel. Further, the film formation of the amorphous compound gel needs to be performed under specific conditions such as heating and light irradiation, and is not versatile.
Further, the technique described in Japanese Patent Application Laid-Open No. 2015-151358 is limited to the formation of a semiconductor thin film and its application technique, and only indium and gallium are disclosed as possible metals, and electric conductivity is described. No consideration is given to the formation of a thermoconducting metal film or metal oxide film.

In general, when manufacturing a large-scale integrated circuit (LSI), various materials used for manufacturing a circuit using a semiconductor or a method for forming a circuit have been studied. However, it can be used to fabricate fine circuits using metals such as copper that have electrical and thermal conductivity, and form metal films and metal oxide films that have good adhesion to various substrates. As for the materials that can be used, the current situation is that materials having practically satisfactory performance have not been obtained.

An object of the embodiment of the present invention is to provide a metal film forming composition capable of easily forming a metal film having excellent adhesion to a substrate.
An object of another embodiment of the present invention is to provide a metal film forming method capable of easily forming a metal film having excellent adhesion to a substrate.

As a result of diligent studies, the present inventors have found that the above-mentioned problems can be solved by a composition for forming a metal film containing a cationic metal complex.
The disclosure includes the following embodiments:
<1> A composition for forming a metal film containing a metal complex represented by the following general formula (1), general formula (2) or general formula (3), a counter anion of the metal complex, and a solvent of the metal complex. thing.

In the general formula (1), M ¹ represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co. L ¹¹ and L ¹² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 1n and 1m each independently represent an integer of 0 to 8, 1n + 1m is in the range of 4-8, an integer determined according to the valence of the metal atom represented by M ^1.
In the general formula (2), M ² represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co. L ²¹ and L ²² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 2n and 2m each independently represent an integer of 0 to 4, and 2n + 2m represents an integer in the range of 2 to 4 and determined according to the valence of the metal atom represented by ^{M 2.}
In the general formula (3), M ³ represents a metal atom selected from the group consisting of Cu, Ni, Mn, and Co. L ³¹ and L ³² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 3n and 3m each independently represent an integer of 0 to 8, 3n + 3m is in the range of 2-8, an integer determined according to the valence of the metal atom represented by M ^3.

<2> The composition for forming a metal film according to <1>, wherein the metal complex is a metal complex represented by the general formula (1) and contains at least one selected from the compound group shown below. In the following compounds, M ¹ independently represents Ag, Cu, Li, Ni, Mn, Zn, or Co.

<3> The composition for forming a metal film according to <1>, wherein the metal complex is a metal complex represented by the general formula (3) and contains at least one selected from the compound group shown below. In the following compounds, M ³ represents Cu, Ni, Mn, or Co.

<4> The metal film according to any one of <1> to <3>, wherein the content of the metal atom contained in the total amount of the metal film forming composition is in the range of 0.5% by mass to 10% by mass. Formation composition.
<5> The counter anion of the metal complex is a counter anion derived from a compound selected from a carboxylic acid, a carboxylic acid complex, an aminopolycarboxylic acid, an aminopolycarboxylic acid complex, an amino acid compound, and an amino acid compound complex. The composition for forming a metal film according to any one of <1> to <4>, which comprises at least one kind.
<6> The composition for forming a metal film according to any one of <1> to <5>, wherein the counter anion of the metal complex contains the same metal atom as the metal atom contained in the metal complex.
<7> The composition for forming a metal film according to any one of <1> to <6>, wherein the counter anion of the metal complex contains a counter anion having the following structure.

<7> A step of applying the metal film-forming composition according to any one of <1> to <6> onto the base material to form a metal film-forming composition layer, and on the base material. A step of heating the composition layer for forming a metal film formed in the above under a temperature condition of 30 ° C. or higher to form a metal film.
Metal film forming method including.
<8> A step of applying the metal film-forming composition according to any one of <1> to <6> onto the base material to form a metal film-forming composition layer, and the base material. A method for forming a metal film, comprising a step of irradiating the above-formed composition layer for forming a metal film with ultraviolet rays to form a metal film.

According to one embodiment of the present invention, it is possible to provide a composition for forming a metal film capable of easily forming a metal film having excellent adhesion to a substrate.
Further, according to another embodiment of the present invention, it is possible to provide a metal film forming method capable of easily forming a metal film having excellent adhesion to a substrate.

It is a graph which shows the absorption spectrum of the composition for forming a metal film of Example 1. FIG. It is a graph which measured the X-ray diffraction (XRD) of the copper film formed by the composition for forming a metal film of Example 1. FIG. 6 is a scanning electron microscope (SEM) photograph of a copper film formed by the composition for forming a metal film of Example 1. It is a graph which shows the light transmission spectrum of the copper film obtained in Example 1. FIG. It is a graph which shows the infrared reflection spectrum of the copper film obtained in Example 1. FIG.

Hereinafter, the present disclosure will be described in detail with reference to specific embodiments, but the present disclosure is not limited to the following embodiments, and includes various modified examples as long as it does not contradict the gist thereof.
The numerical range described by using "~" in the present specification represents a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value.
In the present specification, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.
In the present specification, the amount of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. do.

<Composition for forming a metal film>
(Metal complex represented by the general formula (1), the general formula (2) or the general formula (3))
The composition for forming a metal film of the present disclosure includes a metal complex represented by the following general formula (1), general formula (2) or general formula (3) (hereinafter, may be referred to as a specific metal complex) and the above. It contains a counter anion of a metal complex and a solvent of the metal complex.

In the general formula (1), M ¹ represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co.
In the general formula (2), M ² represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co.
In the general formula (3), M ³ represents a metal atom selected from the group consisting of Cu, Ni, Mn, and Co.
Each of M ^{1 to} M ³ is selected according to the intended use of the metal film to be formed. According to the composition for forming a metal film of the present disclosure, a metal oxide film containing the same metal can be formed.
Among them, Cu, Li, Ni and the like are preferable as ^{M 1} and M ² from the viewpoint of versatility. As M ³ , Cu, Ni and the like are preferable. Further, ^{by using Ag as M 2} , it is possible to form a silver film or a silver oxide film having good adhesion to a substrate at a low temperature.

L ¹¹ , L ¹² , L ²¹ , L ²² , L ³¹ and L ³² are independently such as NH ₃ ligand, R ¹ NH ₂ ligand, OH ₂ ligand, or ethylenediamine, hexamethylene diamine, etc. It represents a ligand derived from diamine, and R ¹ represents an alkylene group.
1n, 1m, 2n, 2m, 3n and 3m each independently represent an integer of 0 to 8. 1n + 1m is in the range of 4 to 8, 2n + 2m is in the range of 2 to 4, 3n + 3m is in the range of 4 to 8, and the valences of the metal atoms represented by ^{M 1 to} M ^{3, respectively.} Represents an integer determined accordingly. Therefore, both 1n and 1m, 2n and 2m, and 3n and 3m are never zero.
^{Among them, L 11} , L ¹² , L ²¹ , L ²² , L ³¹ and L ³² are NH ₃ ligand, OH ₂ ligand, and R from the viewpoint of solubility in solvent, stability, coatability, etc. ^{It is preferably 1} NH ₂ ligand or the like. L ¹¹ and L ¹² , L ²¹ and L ²² , L ³¹ and L ³² may be the same or different from each other, respectively.
When L ¹¹ , L ²¹ or L ³¹ is an R ¹ NH ₂ ligand, R ¹ is an alkylene group, and an alkylene group having 1 to 5 carbon atoms is preferable.

The composition for forming a metal film of the present disclosure is useful not only for forming a metal film but also for forming a metal oxide film. Therefore, hereinafter, in the present specification, the "metal film" obtained by the composition for forming a metal film of the present disclosure is used in the sense of including a metal oxide film containing the metal.
As a method of forming a metal oxide film using the composition for forming a metal film of the present disclosure, a method of further heat-treating a metal film formed by the composition for forming a metal film to form an oxide film, a method of forming a metal film. When forming a metal film using the composition for use, a method of positively creating an oxidizing atmosphere and heat-treating under the oxidizing atmosphere can be mentioned.

The following are examples of more specific structures of the specific metal complex represented by the general formula (1) or the general formula (2), but the structure is not limited to the following. In the following structure, M ¹ and M ² independently represent Ag, Cu, Li, Ni, Mn, Zn, or Co, respectively.

Among them, as the specific metal complex, the specific metal complex represented by the following structure represented by the general formula (1) is preferable. In the following structure, M ¹ independently represents Ag, Cu, Li, Ni, Mn, Zn, or Co.

The following is an example of a more specific structure of the specific metal complex represented by the general formula (3), but the structure is not limited to the following. In the structure below, M ³ represents Cu, Ni, Mn, or Co.

The specific metal complex can be obtained by dissolving a metal salt compound or the like in a solvent that dissolves the metal salt compound.
The metal salt compound is not particularly limited as long as it is a metal salt compound capable of forming a cationic metal complex when dissolved in a solvent. Examples of the metal salt compound include a metal salt compound represented by M (X) p, a metal salt compound represented by (R-COO) pM, and the like. M represents a metal atom, and X represents at least one selected from the group consisting of halogen atoms such as Cl and F, and hydroxides.
R represents a monovalent substituent selected from a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, and the like. When R is an alkyl group, at least a part of the hydrogen atom in the alkyl group may be substituted with a halogen atom or the like. p is an integer corresponding to the valence of the metal atom M.

For example, a copper salt compound dissociated in a solvent by dissolving a copper salt compound such as copper halide, copper formate, or copper carboxylate in a solvent such as water or alcohol exists as a cationic copper complex in the solvent. do. At this time, by including the counter anion of the cationic metal complex in the solvent in addition to the cationic metal complex such as the cationic copper complex, the stability of the composition for forming a metal film is further improved.
Hereinafter, specific examples of the specific metal complex that can be used in the composition for forming a metal film of the present disclosure are shown. The specific metal complex is not limited to the following examples.

The composition for forming a metal film of the present disclosure may contain only one specific metal complex, or may contain two or more specific metal complexes.
When two or more kinds are contained, for example, a combination of specific metal complexes containing the same metal and different ligands, a combination of metal complexes containing different metals, and the like can be mentioned.

The content of the specific metal complex in the composition for forming a metal film is determined by the charging ratio of the metal salt in the composition for forming a metal film.
In general, it is difficult to measure the content of a metal complex with respect to the total amount of the composition for forming a metal film. However, the physical characteristics of the metal film formed by the metal film forming composition depend on the metal content in the metal film forming composition.
From the viewpoint of being able to form a dense and uniform metal film, the metal content with respect to the total amount of the metal film forming composition is preferably in the range of 0.5% by mass to 10% by mass, and is preferably 1% by mass. More preferably, it is in the range of ~ 8% by mass.
When the metal content is in the above range, the structure of the metal film formed by the metal film forming composition becomes more uniform, and the electrical conductivity and the thermal conductivity become better.
The content of the metal in the composition for forming a metal film can be measured, for example, by the method described in "Basics of Complex Chemistry Werner Complex and Organic Metal Complex" (KS Chemistry Special Book: Kodansha, 1989).

(solvent)
The solvent contained in the composition for forming a metal film of the present disclosure can be used without limitation as long as it is a solvent capable of dissolving the above-mentioned specific metal complex.
Dissolving a specific metal complex means that when a mixture containing a metal salt compound containing 1% by mass of a metal, a complex-forming material, and a solvent is prepared, solid content such as turbidity is not visually observed and is uniform. It can be confirmed by becoming a mixture.
Examples of the solvent include water, alcohol, and alkyl ethers of polyhydric alcohols.
Examples of the alcohol include monohydric alcohols having 1 to 10 carbon atoms such as methanol, ethanol, isopropanol, n-propanol, isobutanol, and n-butanol, ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, and glycerin. Price alcohol can be mentioned.
Examples of the lower alkyl ether of the polyhydric alcohol include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether.

From the viewpoint of solubility and handleability of the metal salt compound, it is preferable to contain water and a monohydric alcohol having 1 to 5 carbon atoms as the solvent, and water, methanol, ethanol, propanol and the like are more preferable.
When preparing the composition for forming a metal film of the present disclosure, it is one of the advantages that a uniform composition for forming a metal film containing a metal complex can be obtained even when water is used as a solvent.

The composition for forming a metal film of the present disclosure may contain only one type of solvent, or may contain two or more types of solvent.
The content of the solvent in the composition for forming a metal film is not particularly limited as long as it can dissolve the specific metal complex.
For example, the content of the solvent can be in the range of 90% by mass to 99.5% by mass and preferably in the range of 95% by mass to 98% by mass with respect to the total amount of the composition for forming a metal film.
When the content of the solvent in the composition for forming a metal film is within the above range, the handleability of the composition for forming a metal film is improved, and it is possible to more easily form a metal film having a desired thickness by heating. can.

(Counter-anion of specific metal complex)
The composition for forming a metal film of the present disclosure includes a cationic metal complex which is a specific metal complex and a solvent, as well as a counter anion of the cationic metal complex (hereinafter, may be simply referred to as “counter anion”).
When the composition for forming a metal film contains a counter anion, the stability of the specific metal complex in the composition for forming a metal film becomes better.
The counter anion includes at least one of a counter anion derived from a compound selected from a carboxylic acid, a carboxylic acid complex, an aminopolycarboxylic acid, an aminopolycarboxylic acid complex, an amino acid compound, and a complex of amino acid compounds. Is preferable.
These compounds that can be counter anions can take the form of counter anions by being dissolved in a solvent in the composition for forming a metal film. Further, the counter anion may be produced as a result of adding a metal salt compound to the composition for forming a metal film and dissociating the metal salt compound in a solvent. For example, by adding a metal salt of an amino acid compound to a composition for forming a metal film, a counter anion, which is a metal complex of amino acids, may be produced.
In preparing the composition for forming a metal film, a compound forming a preferable counter anion may be separately added to the solvent to generate a counter anion in the composition.
Further, a preferable counter anion may be prepared in advance and added to the composition for forming a metal film in the form of a counter anion.

Specific examples of the carboxylic acid include formic acid and acetic acid.
Aminopolycarboxylic acids include nitrilotriacetic acid, nitrilotripropionic acid, carboxyethyliminodiacetic acid, carboxymethyliminodipropionic acid, iminodiacetic acid, iminonipropionic acid, hydroxyethyliminodiacetic acid, and hydroxyethyliminodipropionic acid. , Methoxyethylimino diacetic acid, alanin-N, N-diacetic acid, serine-N, N-diacetic acid, isoserine-N, N-diacetic acid, aspartic acid-N, N-diacetic acid, glutamate-N, N- Examples thereof include diacetic acid and ethylenediaminetetraacetic acid.
Examples of the amino acid compound include alanine, β-alanine, glycine, serine, isoserine, aspartic acid, glutamic acid, sarcosine, leucine, isoleucine and the like.
In addition, in this specification, "amino acid compound" is used in the meaning which includes "amino acid" itself and "derivative of amino acid".
The counter anion derived from the above-mentioned carboxylic acid, aminopolycarboxylic acid, and amino acid compound may take the form of a complex of these compounds in the composition for forming a metal film. That is, the counter anion contains at least one of a counter anion derived from a compound selected from a carboxylic acid, a carboxylic acid complex, an aminopolycarboxylic acid, an aminopolycarboxylic acid complex, an amino acid compound, and a complex of amino acid compounds. be able to.

Further, the counter anion derived from these compounds may contain a metal atom in the structure. That is, the counter anion may be an anion having a metal complex structure containing a metal atom.
The counter anion is preferably a counter anion containing the same metal atom as the metal atom contained in the specific metal complex contained in the composition for forming a metal film. When the counter anion contains the same metal atom as the metal atom contained in the coexisting specific metal complex, the structure of the metal film formed by the metal atom becomes more precise.
It is considered that this is because the metal atom is present at a higher density in the composition layer for forming a metal film by forming an interaction between the cationic metal complex and the counter anion containing the metal atom.

More specifically, the counter anions include, for example, [Cu (edta)] ^2- , [Cu (ida) ₂ ] ^2- , HCOO ⁻ , CH ₃ COO ⁻ , Cl ⁻ , and anions having the structures shown below. Examples include a sex metal complex. edta represents ethylenediaminetetraacetic acid and ida represents iminodiacetic acid.

The composition for forming a metal film may contain only one type of counter anion, or may contain two or more types of counter anions.
It is preferable that the composition for forming a metal film contains an anionic metal complex such as the above structure as a counter anion because the obtained metal film becomes denser. At this time, the metal M contained in the anionic metal complex is preferably the same ^{as the metal M 1} , M ² or M ^{3 contained in the specific metal complex.}
By including a metal contained in a cationic metal complex, which is a specific metal complex contained in the composition for forming a metal film, and an anionic metal complex having the same metal M as a counter anion, the composition for forming a metal film can be used. The structure of the formed metal film becomes denser.
For example, [Cu (edta)] ^2- , [Cu (ida) ₂ ] ^2- , and the anionic metal complex having the structure shown above are specific metal complexes containing Cu atoms because they contain Cu atoms in the structure. When used in combination with, it is useful as a counter anion that forms a denser copper film.

(Other ingredients)
The composition for forming a metal film of the present disclosure may contain a specific metal complex, a counter anion of the specific metal complex, and a solvent, as well as other known additives depending on the purpose, as long as the effect is not impaired.

(Preparation of composition for forming a metal film)
The composition for forming a metal film can be prepared by dissolving a metal salt compound forming a specific metal complex in a solvent. A metal salt compound is added to the solvent, and the solvent is dissolved while stirring. The metal salt compound forms a cationic metal complex in the solvent. The solvent may contain a compound such as an ammonium compound and a compound capable of forming a complex with a metal.
Other components can be added as needed. The timing of addition of other components is not particularly limited. It can be appropriately selected and added according to the characteristics of the components.
The metal salt compound forming the specific metal complex may be dissolved in a solvent at room temperature (25 ° C.). From the viewpoint of more efficient dissolution, the solvent can be heated to 30 ° C. to 60 ° C. for dissolution.
Visually, stirring of the solvent can be continued until the metal salt compound is dissolved to form a transparent uniform solution, and a composition for forming a metal film can be prepared.

In the composition for forming a metal film of the present disclosure, since the metal complex is uniformly dissolved in a solvent, the metal film formed by using the metal complex has a dense structure, and has electrical conductivity and thermal conductivity. Excellent for. Further, since the specific metal complex has at least one of an ammonium group, a ligand derived from water, and a ligand derived from ethylenediamine, the adhesion to an inorganic substrate, particularly a glass substrate, is good, and the specific metal complex is specified. The metal film formed by using the metal complex has excellent adhesion to the substrate.
Therefore, the composition for forming a metal film of the present disclosure can form a metal film that is dense and has excellent adhesion to a substrate, and is applied to various fields that require a metal film, particularly a copper thin film. be able to.

<Metal film forming method (1)>
In one embodiment of the metal film forming method of the present disclosure, a step of applying the above-mentioned metal film forming composition of the present disclosure to a base material to form a metal film forming composition layer (hereinafter referred to as a metal film forming composition layer). A step (sometimes referred to as step (A)) and a step of heating the metal film-forming composition layer formed on the substrate under a temperature condition of 30 ° C. or higher to form a metal film (hereinafter, step). (B)) and.

The metal film forming method of the present disclosure may include a composition preparation step of preparing a composition for forming a metal film prior to the step (A).
As described above, the above-mentioned composition for forming a metal film of the present disclosure is a cationic metal by mixing a metal salt compound which becomes a metal complex in a solvent, a compound which becomes a counter anion, and a solvent. A composition for forming a metal film containing a complex can be obtained. The precursor method for forming a metal film using a conventionally known anionic metal complex always requires a step of synthesizing the metal complex, but the method using the cationic metal complex of the present disclosure has a special metal complex synthesis. Since no step is required, a composition for forming a metal film useful for forming a metal film can be easily obtained.

[Step (A)]
In the step (A), first, the above-mentioned composition for forming a metal film of the present disclosure is applied onto a substrate on which a metal film is to be formed, and the composition layer for forming a metal film (hereinafter, simply "composition"). Sometimes referred to as a "layer"). The step (A) may further include a step of drying the formed metal film forming composition layer after applying the metal film forming composition.

(Base material)
The base material in the present disclosure can be appropriately selected and used according to the purpose of forming the metal film. That is, a substrate having various physical properties such as heat resistance, dimensional stability, solvent resistance, electrical insulation, workability, gas barrier property, low hygroscopicity, and waterproof property is selected according to the purpose of use of the metal film. Can be used. For example, a material generally used as a circuit board can be used as a base material in the present disclosure.
Among them, inorganic substrates such as glass, ceramics, and metals are preferable from the viewpoint of suppressing deterioration, dimensional change, and the like when heated in the step (B) and having good thermal stability. More specifically, a non-alkali glass substrate, a soda glass substrate, a Pyrex (registered trademark) glass substrate, a glass substrate such as a quartz glass substrate, a semiconductor substrate such as a silicon substrate, a stainless steel substrate, an aluminum substrate, a metal substrate such as a zirconium substrate, etc. , Metal oxide substrates such as alumina substrates, resin substrates such as polyamide and high-density polyethylene, and the like.
The base material may have a single-layer structure or may have a laminated structure using a plurality of different materials. Moreover, you may use the base material which modified the metal. Examples of the metal-modified base material include an aluminum substrate with an oxide film obtained by subjecting an aluminum substrate to an oxidation treatment, an yttrium-stabilized zirconium substrate, a stainless steel substrate, and the like.

The thickness of the base material can be selected according to the purpose of use. Further, a metal film can be formed on the existing member by using the existing member as a base material by using the composition for forming a metal film of the present disclosure.

Any known method can be applied as a method for applying the composition for forming a metal film on the substrate. For example, a spray coating method, a spin coating method, a blade coating method, a bar coating method, a dip coating method, a roll coating method, a die coating method, a flow coating method and the like can be mentioned. Further, the composition for forming a metal film can be applied onto the substrate by the casting method. Further, the composition for forming a metal film may be applied onto the substrate by a printing method such as screen printing or inkjet printing. By using the printing method, the composition layer can be locally formed in a desired region of the substrate.

The thickness of the composition layer for forming a metal film can be selected according to the purpose. Generally, the wet film thickness is preferably in the range of 1 μm to 10 μm, and more preferably in the range of 3 μm to 5 μm.

[Drying of composition layer]
The composition layer after coating can be subjected to a step of drying the composition layer before being heated in the step (B). The drying may be natural drying at room temperature or heat drying. The temperature at the time of heat drying is not particularly limited, but can be in the range of 30 ° C. to 100 ° C. in consideration of drying efficiency and the like.
As a heating method for heat-drying, a known heating means can be appropriately selected and applied. Examples of the heating method include a method of contacting a plate-shaped heater, a heat roll, etc. from the back surface of the base material, a method of passing through a heating zone such as an electric furnace, a method of irradiating energy rays such as infrared rays and microwaves, and the like. ..
The drying time is preferably in the range of 10 seconds to 20 minutes from the viewpoint of productivity.

For the purpose of making the film thickness of the composition layer a required thickness, the composition for forming a metal film may be applied and heated a plurality of times.

[Step (B)]
In this step, the composition layer formed on the base material in the previous step (A) is heated under a temperature condition of 30 ° C. or higher to form a metal film. By the heat treatment, the metal complex is converted into a metal and a metal film is formed on the base material.
The heating conditions are appropriately selected according to the characteristics of the metal.
For example, when M ¹ or M ² is Ag, the formation of a silver film proceeds by a reduction reaction when the composition layer is formed. From the viewpoint of promoting the silver film formation reaction, the composition layer may be heated at a temperature of 30 ° C. or higher. Therefore, when the metal complex in the composition for forming a metal film is a silver complex, the silver film can be formed by the above-mentioned drying step, and the drying step and the heating step can be performed in one step. When a silver oxide film is formed by using a silver-gold complex, the heating temperature can be set to 30 ° C to 500 ° C.
Further, when M ¹ or M ² is a metal atom selected from the group consisting of Cu, Li, Ni, Mn, Zn, and Co, M ³ is from the group consisting of Cu, Ni, Mn, and Co. In the case of the selected metal atom, the heating is preferably performed under a temperature condition of 200 ° C. or higher, and more preferably performed under a temperature condition of 250 ° C. or higher.
The upper limit of the heating temperature is not particularly limited, and may be appropriately selected depending on the physical properties such as the melting point and softening point of the metal and the heat resistance of the base material to be used. Generally, it is preferably 500 ° C. or lower.

When the counter anion is a counter anion having a metal complex structure containing a metal atom, a specific cationic metal complex and a counter anion having a metal complex structure form an equivalent interaction to form a relatively low temperature heating. A dense metal film is formed.
On the other hand, when the counter anion contains a counter anion derived from a carboxylic acid, the counter anion and the specific cationic metal complex form an interaction, and the organic substance is removed by heating at a relatively low temperature, which makes it easy. A uniform metal film is formed.

The heating conditions in the step (B), for example, the maximum temperature in heating, the temperature rising conditions, the heating time, and the like can also be appropriately selected depending on the characteristics of the metal.
It is also preferable to heat and fire the metal film by raising the temperature to a heating temperature selected according to the type of metal and then maintaining the heating temperature for several minutes.

The heating may be performed in an atmospheric atmosphere or in an inert gas atmosphere. Examples of the inert gas when the operation is carried out in an atmosphere containing the inert gas include nitrogen gas, helium gas, argon gas and the like.
When the heat treatment is performed in an atmosphere where the oxygen concentration is low, such as under an inert gas atmosphere, the oxygen concentration is preferably 10 ppm or less.

After the step (B) is carried out, a firing treatment (annealing treatment) for further heating the formed metal film can be performed for the purpose of improving the uniformity of the formed metal film. The firing process can be performed at 200 ° C to 500 ° C.

<Metal film forming method (2)>
In another embodiment of the metal film forming method of the present disclosure, a step (step (step)) of applying the above-mentioned metal film forming composition of the present disclosure to a base material to form a metal film forming composition layer. A)) and a step of irradiating the metal film forming composition layer formed on the substrate with ultraviolet rays to form a metal film (hereinafter, may be referred to as step (C)).
The step (A) in the metal film forming method (2) of the present embodiment is the same as the step (A) in the embodiment shown in the metal film forming method (1) described above.
In the metal film forming method (2) of the present embodiment, the metal film is formed by applying ultraviolet rays (step (C)) instead of heating (step (B)) in the above-described embodiment to apply energy. Form.
The mechanism by which the metal film is formed by ultraviolet irradiation is not clear, but it is estimated as follows.
When the specific metal complex contained in the composition for forming a metal film receives light energy from the outside due to irradiation with ultraviolet rays, a transition accompanied by electron transfer between atoms, that is, a charge transfer transition occurs. It is considered that the specific metal complex is converted into a metal along with the charge transfer transition, and a dense metal film is formed.

In step (C), irradiation of ultraviolet rays (hereinafter, may be referred to as UV (Ultraviolet) light) can be performed using a known light source of UV light.
Examples of the light source of UV light include a UV lamp and a UV laser. From the viewpoint of uniformly irradiating a large area with ultraviolet rays, it is preferable to use a UV lamp as a light source.
The UV lamp used in the step (C) is not particularly limited. Specific examples of the UV lamp include an excima lamp, a heavy hydrogen lamp, a low pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a helium lamp, a carbon arc lamp, a cadmium lamp, a electrodeless discharge lamp and the like. Be done. Among them, the low pressure mercury lamp is preferable from the viewpoint that the composition layer can be easily converted into a metal film.
The ultraviolet irradiation may be carried out over the entire surface of the composition layer for forming a metal film, or may be carried out in a pattern. Examples of the patterned exposure include a method of irradiating UV light through a mask using a UV lamp. By irradiating the UV light in a pattern, the conversion of the composition layer for forming a metal film into a metal film proceeds in the irradiated portion of the UV light.

The UV light can be irradiated, for example, by using UV light having a wavelength of 380 nm or less, more preferably UV light having a wavelength of 300 nm or less, under the condition that the illuminance on ^{the surface of the composition layer is 10 mW / cm 2 or more.} It is preferable from the viewpoint that a metal film can be formed in a shorter time.
The illuminance of the UV light irradiating the composition layer can be measured using, for example, an ultraviolet photometer (UV-M10 manufactured by ORC Manufacturing Co., Ltd., receiver UV-25).
The irradiation of UV light may be performed under atmospheric pressure, under an inert gas atmosphere, or under vacuum. Further, the irradiation with UV light may be performed in any gas. Above all, from the viewpoint of easy conversion, UV light irradiation is preferably performed under atmospheric pressure.

The temperature of the substrate in the step (C) is preferably 100 ° C. or lower. By forming a metal film by irradiation with ultraviolet rays, it becomes easy to form a metal film on a resin substrate having low heat resistance. The temperature of the substrate can be measured using a known, contact or non-contact thermometer.
The irradiation time of UV light can be appropriately determined depending on the illuminance of UV light. Above all, from the viewpoint of productivity, it is preferably 5 seconds or more and 120 minutes or less.

(Metal film)
The thickness of the metal film obtained by the metal film forming method (1) or the metal film forming method (2) of the present disclosure described above is selected according to the purpose. Since the metal film forming method (1) and the metal film forming method (2) of the present disclosure use the metal film forming composition of the present disclosure which is uniformly contained in a state where the copper complex is dissolved, for example, from 10 nm. An extremely thin film of 200 nm can be formed.
Further, for example, by applying a spray coating method or the like to make the composition layer thicker, it is possible to form a metal film having a thickness on the order of several microns. Further, by repeating the step (A) for forming the composition layer and the heating (step (B)) or the ultraviolet irradiation (step (C)) a plurality of times, a metal film having a thicker film thickness is formed. Can be easily formed.
The thickness of the metal film formed by one coating and heating using the composition for forming a metal film of the present disclosure is preferably 50 nm to 150 nm.
The thickness of the obtained metal film can be measured by a known measuring method by observing the cross section of the metal film formed on the base material.

The metal film obtained by the metal film forming method (1) or the metal film forming method (2) of the present disclosure using the metal film forming composition of the present disclosure is based on a composition containing only a specific metal complex as a metal material. Since the specified metal complex is formed and converted into a metal film through heating (step (B)) or ultraviolet irradiation (step (C)) from a state of being dissolved in a solvent, the formed metal film has a dense structure. Yes, it has excellent electrical and thermal conductivity.
When the metal film is formed by using a metal film forming composition containing only a specific metal complex having a single metal as a metal material, the content of the metal in the formed metal film is 90% by mass or more. It is preferably present, and more preferably 95% by mass or more.
The content of the metal of interest in the metal film can be measured, for example, by X-ray diffraction (XRD).
The content of impurities in the metal film obtained by the composition for forming a metal film is extremely small.
Although a small amount of solvent-derived impurities may remain in the metal film, they are mainly carbon atoms derived from the solvent as a raw material, and there is no concern that the characteristics of the formed metal film may be impaired. This can be said to be a great advantage as compared with electroless plating films that require a reducing agent and metal films formed by the precursor method using an anionic metal complex.
Further, by carrying out the step (A) and further carrying out the step (B) or the step (C) using the above-described composition for forming a metal film of the present disclosure, the temperature is lower than that of the conventional method. It is also one of the advantages of the metal film forming method of the present disclosure that a dense metal film is formed even under the conditions.

The metal film formed by the method of the present disclosure may be uniformly formed over the entire surface of the base material, or may be formed in a pattern. Further, after forming a uniform metal film, it is possible to form a patterned metal film by patterning using a known method such as etching depending on the purpose.

Hereinafter, examples of embodiments of the present invention will be specifically described with reference to examples, but the present disclosure is not limited to the following examples.

[Example 1]
(1. Preparation of composition for forming a metal film)
(1-1. Preparation of liquid containing specific metal complex)
2.1 g of copper (II) formate tetrahydrate and 5 g of ethanol were added to a 100 mL (milliliter) Erlenmeyer flask. While stirring this solution, 2.2 g (37.2 mmol) of propylamine was added, and the mixture was stirred at room temperature (25 ° C.) for 1 hour to obtain a specific metal complex-containing liquid.
The obtained specific metal complex-containing liquid was a transparent uniform solution when visually observed. The concentration of the specific metal complex contained in the specific metal complex-containing liquid is 1.0 mmol / g.
The specific metal complex-containing liquid contains a cationic copper complex having the structure shown below and a counter anion HCOO ⁻ .

(1-2. Preparation of anti-anion-containing liquid)
In a 100 mL (milliliter) Erlenmeyer flask, _{4.0 g of Cu (H 2} edta) and H ₂ O was measured, and 4 g of ethanol was added. While stirring the solution was added 2.81g dibutylamine, to give an anionic metal complex of the following structure was refluxed for 1 _h, the _(C 4 _{H 9)} and 2 NH ^+, contains a counter anion-containing solution ..
The obtained counter anion-containing liquid was a transparent uniform solution when visually observed. The concentration of the anionic metal complex having the following structure contained in the counter anion-containing liquid was 1.0 mmol / g.

(1-3. Preparation of composition for forming a metal film)
The obtained specific metal complex-containing liquid and the counter anion-containing liquid were mixed at a mass ratio of 1: 8, that is, at a ratio of 8 parts by mass of the counter anion-containing liquid to 1 part by mass of the specific metal complex-containing liquid. The composition for forming a metal film of Example 1 was obtained.

(2. Measurement of absorption spectrum of cationic copper complex)
The obtained composition for forming a metal film was diluted with ethanol to prepare a diluted solution (sample) having a copper complex concentration of 0.1 mmol / g. The absorption spectrum of the obtained sample was measured with an absorbance photometer (u-2800: Hitachi, Ltd.).
The absorption spectrum is shown in FIG. As is clear from FIG. 1, the sample showed a spectrum with an absorption at 647 nm. That is, it was confirmed that the composition for forming a metal film of Example 1 contained a copper complex.
Further, when the mixing ratio of the counter anion-containing liquid in the metal film forming composition was changed to change the content of the anionic complex in the metal film forming composition, it was confirmed that the absorption position in the absorption spectrum was shifted. rice field. This means that the content of heterogeneous complexes having different structures from each other has increased in the composition for forming a metal film.

(3. Formation of metal film)
The obtained composition for forming a metal film is applied to one side of a quartz glass substrate (manufactured by Akishima Glass Co., Ltd.) having a thickness of 1.5 mm by a spin coating method in an amount such that the coating film thickness is 3 μm to obtain a metal film. A composition layer for formation was formed.
Then, the composition layer for forming a metal film was dried at 70 ° C. for 10 minutes.

The laminate in which the composition layer for forming a metal film is formed on the substrate is heated in a tubular furnace at a heating rate of 0.5 ° C./sec until the maximum temperature reaches 350 ° C. to reach the maximum temperature. After maintaining for 15 minutes and heating, a copper film having a thickness of 40 nm was formed on the glass substrate.
Then, the obtained copper film was allowed to cool to room temperature.

(Evaluation of copper film)
The obtained copper film was evaluated as follows.
1. 1. Component analysis X-ray diffraction (XRD) was performed on the obtained copper film using an MXP-18AHF22 device and Bruker AXS in a parallel beam optical system with an incident angle of 0.3 °, and 2θ was 0 from 30 ° to 50 °. It was measured by measuring the intensity in steps of 0.05 ° for a fixed time of 6 seconds each.
The results are shown in FIG. As is clear from FIG. 2, according to the XRD pattern, it can be seen that the formed copper film is a single phase of copper.

2. 2. Membrane structure FIG. 3 shows a photograph of a copper film formed by the metal film forming composition of Example 1 taken with a scanning electron microscope (SEM). As is clear from FIG. 3, it can be seen that the formed copper film is formed of dense copper particles without observing agglomerated large particle size particles or conspicuous voids.

3. 3. Electrical conductivity The obtained copper film was measured for electrical conductivity by the following method. The electrical resistance of the copper film was measured at 5 points by the four-probe method, and the average value was calculated at 3 points excluding the maximum and minimum values of the measured values, and the value obtained was taken as the electrical resistance value of the copper film.
The measurement was performed using a digital multimeter: Iwatsu Measurement Co., Ltd., VOAC7512 and KEITHLEY, Model2010 Multimeter.
As a result, the electric conductivity was 4.7 × 10 ^-5 Ωcm, and although it was a thin film, it showed sufficient electric conductivity for practical use.

4. Adhesion The adhesion of the obtained copper film to the glass substrate was measured by the following method.
The adhesion of the thin film was measured by a tensile tester: a thin film adhesion strength measuring machine: Romulus (trade name), Phototechnica Co. Ltd.
The tensile strength test sample was prepared as follows.
The stud pin coated with the epoxy adhesive is fixed vertically to the copper film surface on the glass substrate using a clip and adhered, and heated in a dryer at a temperature of 150 ° C. for 1 hour to cure the epoxy adhesive. Then, the inside of the dryer was cooled to room temperature (25 ° C.) and then taken out, and the clip fixing the stud pin was removed to prepare a sample for tensile strength test in which the stud pin was vertically adhered. The stud pin was made of aluminum and had an adhesive surface of φ2.7 mm.
The substrate provided with the copper film was fixed to the reinforcing plate of the tensile tester, and the stud pin was sandwiched between the grips of the tensile tester and pulled vertically downward to measure the strength when the copper film was peeled off from the glass substrate. .. The measurement was performed 5 times, and the average intensity was obtained from the measurement results of 3 points excluding the maximum value and the minimum value of the measured intensity.
As a result, it was found that the peel strength was 36 MPa, and the copper film had good adhesion to the glass substrate.

5. Light transmittance The transmitted / reflected spectrum of the obtained copper film was measured by the following method to obtain the light transmittance.
The transmission / reflection spectrum of the copper film was measured by UV-3600 SUPECTROPHOTOMETER (Shimadzu Corporation). The transmission spectrum was measured in the range of 220 nm to 2500 nm in the double beam mode with air as a reference. The reflection spectrum was measured in the range of 220 nm to 2500 nm in the double beam mode with barium sulfate as a reference. The results are shown in FIG.
From the graph of FIG. 4, the visible light transmittance of the obtained copper film is about 40%, and the transparency is such that characters can be visually recognized through the copper film formed on the glass substrate. I understand.

5. Infrared reflectance For the obtained copper film, use the same UV-3600 SUPECTROPHOTOMETER (Shimadzu Seisakusho Co., Ltd.), which is the same as the device used for the measurement of light transmittance described above, to emit light of 800 nm to 2500 nm (infrared measurement). It was incident on the measurement surface and the reflectance was measured. The results are shown in FIG.
From the graph of FIG. 5, the infrared reflectance of the obtained copper film is 50% at 1200 nm and 100% at 2500 nm, and the obtained copper film has an infrared blocking effect, and is particularly excellent in far infrared blocking property. You can see that.

(Industrial application field)
The metal film formed by using the composition for forming a metal film of the present disclosure has good electrical conductivity and thermal conductivity even in a thin layer, and has good adhesion to a substrate, so that it can be applied to various fields. can do.
The composition for forming a metal film of the present disclosure includes, for example, a circuit of a large-scale integrated circuit (LSI), a solar cell wiring, a trench embedded wiring, an electromagnetic wave shield, an infrared blocking glass, a heat reflecting glass, and heat conduction of a vacuum collector. It is suitably used for a member, an antibacterial material utilizing the characteristics of silver or copper as a metal, a heat medium tube, and the like.

All documents, patent applications, and technical standards described herein are to the same extent as if the individual documents, patent applications, and technical standards were specifically and individually stated to be incorporated by reference. Incorporated by reference herein.

Claims (10)

The metal complex represented by the following general formula (1), general formula (2) or general formula (3), the counter anion of the metal complex, and the solvent of the metal complex are contained, and the counter anion of the metal complex is A composition for forming a metal film, which comprises the same metal atom as the metal atom contained in the metal complex.

In the general formula (1), M ¹ represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co. L ¹¹ and L ¹² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 1n and 1m each independently represent an integer of 0 to 8, 1n + 1m is in the range of 4-8, an integer determined according to the valence of the metal atom represented by M ^1.
In the general formula (2), M ² represents a metal atom selected from the group consisting of Ag, Cu, Li, Ni, Mn, Zn, and Co. L ²¹ and L ²² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 2n and 2m each independently represent an integer of 0 to 4, and 2n + 2m represents an integer in the range of 2 to 4 and determined according to the valence of the metal atom represented by ^{M 2.}
In the general formula (3), M ³ represents a metal atom selected from the group consisting of Cu, Ni, Mn, and Co. L ³¹ and L ³² independently represent an NH ₃ ligand, an R ¹ NH ₂ ligand, an OH ₂ ligand, or a diamine-derived ligand, and R ¹ represents an alkylene group. 3n and 3m each independently represent an integer of 0 to 8, 3n + 3m is in the range of 2-8, an integer determined according to the valence of the metal atom represented by M ^3. The composition for forming a metal film according to claim 1, wherein the metal complex is a metal complex represented by the general formula (1) and contains at least one selected from the compound group shown below. In the following compounds, M ¹ independently represents Ag, Cu, Li, Ni, Mn, Zn, or Co.

The composition for forming a metal film according to claim 1, wherein the metal complex is a metal complex represented by the general formula (3) and contains at least one selected from the compound group shown below. In the following compounds, M ³ represents Cu, Ni, Mn, or Co.

The composition for forming a metal film according to any one of claims 1 to 3, wherein the content of metal atoms contained in the total amount of the composition for forming a metal film is in the range of 0.5% by mass to 10% by mass. thing. The counter anion of the metal complex is at least one of a counter anion derived from a compound selected from a carboxylic acid, a carboxylic acid complex, an aminopolycarboxylic acid, an aminopolycarboxylic acid complex, an amino acid compound, and an amino acid compound complex. The composition for forming a metal film according to any one of claims 1 to 4, wherein the composition comprises. The fifth aspect of claim 5, wherein the counter anion of the metal complex contains at least one counter anion derived from a compound selected from the group consisting of a carboxylic acid complex, an aminopolycarboxylic acid complex, and an amino acid compound complex. Composition for forming a metal film. The aminopolycarboxylic acid complex includes a nitrilo triacetic acid complex, a nitrilo tripropionic acid complex, a carboxyethyl imino diacetic acid complex, a carboxymethyl imino dipropionic acid complex, an imino diacetic acid complex, and an imino dipropionic acid complex. Complex, hydroxyethyliminodiacetic acid complex, hydroxyethyliminodipropionic acid complex, methoxyethyliminodiacetic acid complex, alanin-N, N-diacetic acid complex, serine-N, N-diacetic acid complex, isoselin At least one selected from the group consisting of a complex of -N, N-diacetic acid, a complex of aspartic acid-N, N-diacetic acid, a complex of glutamic acid-N, N-diacetic acid, and a complex of ethylenediamine tetraacetic acid. The composition for forming a metal film according to claim 6, which comprises. The composition for forming a metal film according to any one of claims 1 to 7, wherein the counter anion of the metal complex contains a counter anion having the following structure.

A step of applying the metal film-forming composition according to any one of claims 1 to 8 onto a substrate to form a metal film-forming composition layer.
A step of heating the composition layer for forming a metal film formed on a substrate under a temperature condition of 30 ° C. or higher to form a metal film.
Metal film forming method including. A step of applying the metal film-forming composition according to any one of claims 1 to 8 onto a substrate to form a metal film-forming composition layer.
A step of irradiating the composition layer for forming a metal film formed on a base material with ultraviolet rays to form a metal film, and a step of forming the metal film.
Metal film forming method including.

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