JP5834499B2 - Metal film forming composition, metal film, metal film forming method and electronic component - Google Patents

Description

  The present invention relates to a metal film forming composition, a metal film, a metal film forming method, and an electronic component.

When producing a metal structure such as a metal wiring or a metal pattern used for a circuit board substrate such as a flexible printed wiring board, it is necessary to first form a homogeneous metal film.
Conventionally, such a metal film is generally formed by a plating method. In the plating method, formation of a seed layer by sputtering and plating are usually required. Since sputtering needs to be performed in a vacuum, there are significant restrictions on the apparatus and operation. In addition, the processing takes a long time and the cost becomes high. In the plating process, the waste liquid treatment of the plating solution is a large environmental problem.

There is a coating method as a method of forming a metal film instead of the plating method. The coating method has a great merit in that it is not necessary to use a process disadvantageous process as described above.
As a coating method, Patent Document 1 proposes a method of forming a silver film using a composition containing silver oxide and a reducing agent such as glycerin.

  However, generally only a thin film can be formed by the coating method. If a composition containing metal particles or the like is used, it is possible to form a thick film to some extent, but if metal particles with a large particle diameter are used to form a metal film having a larger film thickness, It was difficult to form a self-supporting metal film due to insufficient adhesion of the metal. In particular, when metal particles such as copper having a high ionization tendency are used, it is more difficult to form a self-supporting metal film because the metal oxide usually formed on the particle surface is difficult to be reduced. It was.

JP 2004-176079 A

  An object of the present invention is to provide a composition capable of efficiently forming a metal film, whether it is a metal film having a large film thickness or a metal film having a large ionization tendency, and the production of such a metal film. Is to provide a method.

  In order to achieve the above object, the present invention provides a metal-metal oxide composite particle (A1) in which a portion including a surface portion is made of a metal oxide, and a portion other than the portion including the surface portion is made of the metal, and metal oxidation A metal film-forming composition comprising at least one metal oxide-containing particle (A) selected from product particles (A2), alditol (B), and alditol oxide (C). .

In the metal film forming composition, the alditol oxide (C) is preferably the alditol (B) oxide.
In the said metal film formation composition, it is preferable that alditol (B) is glycerol.

In the said metal film formation composition, it is preferable that content of the oxide (C) of the said alditol is 1-50 mass parts with respect to 100 mass parts of the said alditol (B).
Another invention is a metal film having voids obtained from the metal film-forming composition.

The metal film preferably has a thickness of 1 to 100 μm.
In the metal film, the content ratio of voids in the metal film is preferably 5 to 50% by volume when the volume of the metal film is 100% by volume.

In the metal film, the void content in the metal film is preferably 5 to 50% by volume when the volume of the metal film is 100% by volume, and the metal is preferably copper.
Another aspect of the invention is a method for forming a metal film, wherein a gap containing the metal film is filled with a solution containing a metal element, and a metal is generated from the solution containing the metal element.

In the method for forming the metal film, the solution containing the metal element is preferably a solution containing a copper element.
In the method for forming the metal film, the solution containing the copper element is preferably a copper formate solution.

Another invention is a metal film formed by the method for forming a metal film.
Another invention is an electronic component having the metal film.

  When the composition for forming a metal film of the present invention is used, a metal film can be formed efficiently. In particular, the metal film-forming composition of the present invention can be efficiently formed, whether it is a metal film with a large film thickness or a film made of a metal with a large ionization tendency.

1 is an electron micrograph of a copper film formed from the metal film forming composition of Example 1. FIG.

<Composition for forming metal film>
The metal film-forming composition of the present invention is a metal-metal oxide composite particle (A1) in which a part including a surface part is made of a metal oxide, and a part other than the part containing the surface part is made of the metal, and It contains at least one metal oxide-containing particle (A) selected from metal oxide particles (A2), alditol (B), and alditol oxide (C).

Metal oxide-containing particles (A)
The metal oxide-containing particle (A) is a substance that supplies a metal constituting the metal film formed from the present metal film-forming composition. That is, when the present metal film-forming composition is used, a metal film made of the metal contained in the metal oxide-containing particles (A) is formed. For example, when forming a copper film, copper oxide-containing particles are used as the metal oxide-containing particles (A).

  The metal oxide-containing particles (A) are at least one selected from metal-metal oxide composite particles (A1) (hereinafter also referred to as composite particles (A1)) and metal oxide particles (A2). That is, the metal oxide-containing particles (A) may be only the composite particles (A1) or only the metal oxide particles (A2), and the composite particles (A1) and the metal oxide particles (A2). ) And both. When the metal oxide-containing particles (A) include both the composite particles (A1) and the metal oxide particles (A2), the respective metals contained in the composite particles (A1) and the metal oxide particles (A2) are Usually the same type of metal.

For example, when forming a copper film, the metal-metal oxide composite particles (A1) are copper-copper oxide composite particles, and the metal oxide particles (A2) are copper oxide particles.
In the metal oxide-containing particles (A), the metal oxide contained therein is reduced by alditol (B), which will be described later, is converted into metal, and is bonded to each other to form a metal film.

(Metal-metal oxide composite particles (A1))
The composite particles (A1) are particles in which a part including the surface part is made of a metal oxide and a part other than the part including the surface part is made of the metal. For example, in the case of copper-copper oxide composite particles, a part including the surface part is made of copper oxide, and the other part is made of copper. The part including the surface part means a part where the surface forms at least a part of the surface of the composite particle (A1). Portions other than the portion including the surface portion are made of the metal. Therefore, in the composite particle (A1), a portion made of a metal oxide is not included in a state where it does not appear on the surface of the composite particle (A1).

  The composite particles (A1) may be particles (composite particles (A1-1)) in which the entire surface portion is made of a metal oxide, or particles (composite particles) in which only a part of the surface portion is made of a metal oxide. Particle (A1-2)). In the composite particle (A1-1), the part made of metal is not included in a state of appearing on the surface of the composite particle (A1). In the composite particle (A1-1), the part made of metal is the composite particle ( It is included in a state appearing on the surface of A1).

  The composite particle (A1-1) is a particle having a core part made of a metal and an outer shell part covering the whole core part and containing the metal oxide. The surface of commercially available metal particles is usually oxidized to form a metal oxide film. This metal oxide film corresponds to the outer shell portion. Therefore, commercially available metal particles usually correspond to metal-metal oxide composite particles (A1-1).

  The 50% by mass average particle diameter (D50) of the composite particles (A1) is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and further preferably 0.1 to 3 μm. When the 50% by mass average particle diameter (D50) of the composite particles (A1) is within the above range, the reduction of the metal oxide constituting the outer shell portion proceeds efficiently, and a thick metal film is formed. It is effective. If the thickness is smaller than 0.1 μm, it may be inconvenient in forming a thick metal film. If it is larger than 10 μm, efficient reduction of the metal oxide may be difficult.

  As a kind of metal which comprises the part which consists of a metal of a composite particle (A1), copper, silver, palladium, nickel, tungsten, ruthenium, chromium, manganese, iron, tin, zirconium, niobium, molybdenum, rhodium, zinc, for example , Lead and antimony. The portion made of metal may be formed of one kind or two or more kinds of metals.

  The metal oxide constituting the part made of the metal oxide of the composite particle (A1) is an oxide of the metal constituting the part made of the metal. For example, when the metal constituting the metal portion is copper, the metal oxide constituting the metal oxide portion is copper oxide, and the metal constituting the metal portion is silver. The metal oxide constituting the metal oxide portion is silver oxide.

  The ratio of the portion made of the metal oxide in the composite particles (A1) is usually 50% by volume or less when the total volume of the composite particles (A1) is 100% by volume. When the ratio of the portion made of the metal oxide to the composite particles (A1) is 50% by volume or less, it is easy to completely reduce the metal oxide, and it is easy to form a pure metal film.

As described above, the commercially available metal particles are usually the metal-metal oxide composite particles (A1) of the present invention.
As the metal oxide-containing particles (A), composite particles (A1) are more preferable than metal oxide particles (A2) from the viewpoint of forming a thick film. Since the composite particle (A1) has a core part that does not need to be reduced, it is only necessary to reduce the outer shell part. Therefore, the particle diameter can be made larger than that of the metal oxide particle (A2), which is thicker by that amount. A metal film can be obtained.

  When the metal particles are left in the atmosphere, the surface is usually oxidized to form metal-metal oxide composite particles (A1-1). By firing the metal particles, the surface is oxidized to form a metal. -A metal oxide composite particle (A1-1) can also be produced. The firing conditions are usually 100 to 600 ° C. and 10 to 1000 minutes. By adjusting the firing conditions, the ratio of the portion made of the metal oxide in the composite particles (A1) can be appropriately determined.

  Further, the particles obtained by pulverizing the composite particles (A1-1) prepared by such firing under appropriate conditions are used as particles containing the composite particles (A1-2) and the metal oxide particles (A2). can do.

(Metal oxide particles (A2))
The metal oxide particles (A2) are particles formed from a metal oxide.
The 50% by mass average particle diameter (D50) of the metal oxide particles (A2) is preferably 0.1 to 5 μm, more preferably 0.1 to 3 μm. When the 50% by mass average particle diameter (D50) of the metal oxide particles (A2) is within the above range, the reduction of the metal oxide efficiently proceeds and it is effective for forming a thick metal film. is there. If the thickness is smaller than 0.1 μm, it may be inconvenient in forming a thick metal film. If it is larger than 5 μm, it may be difficult to completely reduce the metal oxide.

  Examples of the metal oxide constituting the metal oxide particles (A2) include copper, silver, gold, palladium, nickel, tungsten, ruthenium, chromium, manganese, iron, tin, zirconium, niobium, molybdenum, rhodium, zinc, Examples include oxides such as lead and antimony. The metal oxide may be formed of one or more metal oxides.

Alditol (B)
Arditol (B) acts as a reducing agent in the composition for forming a metal film of the present invention, and converts the metal oxide contained in the metal oxide-containing particles (A) into a metal.

  The alditol (B) is not particularly limited as long as it has a function of reducing the metal oxide contained in the metal oxide-containing particles (A) contained in the metal film forming composition. For example, glycerin, erythritol, threitol And sugar alcohols such as ribitol, arabinitol, xylitol, allitol, sorbitol, mannitol, iditol, galactitol and taritol.

Among these, glycerin is particularly preferable because it has a strong reducing power and can efficiently form a metal film from the metal oxide-containing particles (A).
The content of alditol (B) is preferably 100 to 1,000 parts by mass, more preferably 200 to 800 parts by mass with respect to 100 parts by mass of the metal oxide-containing particles (A). When the content of alditol (B) is within the above range, the metal oxide can be efficiently reduced.

Alditol oxide (C)
The alditol oxide (C) is the sugar alcohol oxide exemplified as alditol (B). The alditol oxide (C) generally has a structure formed by oxidizing a hydroxyl group of alditol and converting it to a carbonyl group. In the alditol oxide (C), when the corresponding alditol has a plurality of hydroxyl groups, the number of oxidized hydroxyl groups is not particularly limited.

  Examples of the alditol oxide (C) include dihydroxyacetone and glyceraldehyde, which are glycerin oxides, and erythrose and erythrulose, which are erythritol oxides.

  The composition for forming a metal film of the present invention contains an alditol oxide (C) together with an alditol (B), whereby a metal film can be efficiently formed. Even a metal film having a low ionization tendency can be formed efficiently.

The mechanism of action of the alditol oxide (C) is not necessarily clear, but is presumed as follows.
Taking the case where the metal oxide contained in the metal oxide-containing particle (A) is a copper oxide and the alditol oxide (C) is dihydroxyacetone, which is a glycerin oxide, as an example, the metal of the present invention. In the process of forming a metal film using the film-forming composition, when a chelate bond is formed between the carbonyl oxygen of dihydroxyacetone and the copper atom in the copper oxide, as shown in the following formula (1): Conceivable. It is considered that the reduction by alditol (B) is efficiently performed by the formation of this chelate bond. For this reason, even a metal oxide with a small ionization tendency can be efficiently reduced.

Moreover, it is thought that the chelate bond shown by Formula (1) is formed also between the copper atom of the copper metal produced | generated by reducing copper oxide, and the carbonyl oxygen of dihydroxyacetone. By the formation of the chelate bond, the adhesion between the metal particles formed by reducing the metal oxide of the metal oxide-containing particles (A) is strengthened, and as a result, the metal oxide-containing particles (A) Even when the particle diameter of the film is large, it is considered that a self-supporting film is formed and a thick film can be formed.

The alditol oxide (C) may function as a reducing agent depending on the type thereof. For example, dihydroxyacetone functions as a reducing agent.
When the alditol (B) is glycerin, the glycerin (I) reduces the copper oxide in the metal oxide-containing particles (A) as shown in the following formula (2).

At this time, in glycerin (I), for example, one hydroxyl group is oxidized to dihydroxyacetone (II) having one carbonyl group in the molecule. That is, the dihydroxyacetone (II) functions as the alditol oxide (C) together with the alditol oxide (C) originally contained in the metal film forming composition. Therefore, as shown in (III), this dihydroxyacetone (II) forms a chelate bond with the copper atom of copper oxide and the copper atom of copper metal, and contributes to the efficient metal film formation as described above. I think that.

  Moreover, since this dihydroxyacetone (II) functions as a reducing agent as described above, it reduces the copper oxide in the metal oxide-containing particles (A). At this time, dihydroxyacetone (II) becomes, for example, a compound (IV) having two carbonyl groups in the molecule by oxidizing one hydroxyl group. This compound (IV) functions as an oxide (C) of alditol. Therefore, for example, as shown in (V), this compound (IV) forms a chelate bond with the copper atom of the copper oxide and the copper atom of the metal copper, and contributes to the efficient formation of the metal film as described above. It is thought that.

  Furthermore, since the compound (IV) also functions as a reducing agent, the copper oxide in the metal oxide-containing particles (A) is reduced. At this time, in the compound (IV), the hydroxyl group is further oxidized to become a compound having three carbonyl groups in the molecule. This compound also functions as an alditol oxide (C) and is considered to contribute to the formation of an efficient metal film as described above by forming a chelate bond with the copper atom of copper oxide and the copper atom of copper metal. .

  Thus, since alditol (B) becomes alditol oxide (C) by the reduction reaction of the metal oxide during the formation of the metal film, the concentration of alditol oxide (C) increases during the formation of the metal film. The effect of forming the metal film efficiently becomes greater. Depending on the type of alditol (B), as the glycerin, the oxides generated one after another become the oxide (C) of alditol, so that the effect is further increased.

  When the alditol oxide (C) is an alditol (B) oxide, the alditol of the same kind as the alditol oxide (C) is formed from the alditol (B) by the reduction reaction of the metal oxide during the formation of the metal film. Since the oxide (C) is produced and the same action mechanism is obtained, it is preferable. Therefore, for example, when alditol (B) is glycerin, alditol oxide (C) is preferably dihydroxyacetone, which is an glycerin oxide.

  The content of the alditol oxide (C) is preferably 1 to 50 parts by mass, more preferably 5 to 30 parts by mass, and even more preferably 5 to 20 parts per 100 parts by mass of the alditol (B). Part by mass. When the content of the alditol oxide (C) is within the above range, it is easy to form an efficient metal film as described above.

Other Components The composition for forming a metal film of the present invention may contain components other than the metal oxide-containing particles (A), alditol (B) and alditol oxide (C) as necessary. .
For example, the composition for forming a metal film of the present invention can contain metal particles composed only of metal in addition to the metal oxide-containing particles (A).
In addition, the composition for forming a metal film of the present invention can contain a surfactant, a viscosity modifier, an adhesion aid and the like.

Method for Preparing Metal Film Forming Composition The metal film forming composition of the present invention can be prepared by mixing the above components. There is no restriction | limiting in particular in a mixing method, For example, it can mix using a bead mill etc.

<Metal film>
A metal film can be obtained from the metal film-forming composition of the present invention according to a conventional method. For example, the metal film-forming composition is applied to a substrate to form a coating, and then the coating is heated, irradiated with light, or both to obtain a metal film.

  The coating method of the metal film forming composition is not particularly limited, and examples thereof include a spin coating method, a roll coating method, a dip method, a casting method, a spray method, an ink jet method, a screen printing method, and an applicator method. After apply | coating a composition to a base material, you may dry a coating material as needed. Although the thickness of a coating material is suitably determined by the viscosity etc. of a composition, it is 1-1000 micrometers normally.

  The temperature at the time of heating is preferably 50 ° C to 300 ° C, more preferably 100 ° C to 280 ° C, and further preferably 120 ° C to 250 ° C. When the temperature is in the above range, a metal film having excellent adhesion to the substrate can be efficiently formed in a short time. The heating time is usually 5 to 5000 minutes, preferably 10 to 120 minutes.

Heating can be performed in several stages. For example, first, heating may be performed at a low temperature for a certain period of time, and then heating may be performed at a high temperature for a certain period of time.
Examples of the heating device include a hot plate and a circulation type drying furnace.

  The atmosphere during heating is preferably an atmosphere containing no oxygen gas, such as an inert gas atmosphere, from the viewpoint of suppressing oxidation of the formed metal film. From the viewpoint of productivity and the like, a preferable atmosphere is an atmosphere mainly containing nitrogen gas.

  In the case of performing light irradiation on the coating material, the light used for light irradiation is not particularly limited, but radiation such as charged particle beams such as infrared rays, ultraviolet rays, visible rays, far ultraviolet rays, X-rays, and electron beams (ArF) Excimer laser (including wavelength 193 nm) or KrF excimer laser (including wavelength 248 nm).

When heating and light irradiation are performed, the coated material may be heated before light irradiation, or light irradiation may be performed while heating.
The metal film thus obtained can have a thickness of 1 to 100 μm. As described above, since the metal film-forming composition contains the alditol oxide (C), it is possible to use the metal oxide-containing particles (A) having a large particle diameter. A metal film can be formed.

  In general, in the case of a metal having a small ionization tendency such as copper, it is difficult to form a metal film because the metal oxide formed on the surface of the metal particle is difficult to be reduced. In the case of the composition for forming a metal film of the present invention, by containing the alditol oxide (C), as described above, even a metal oxide having a low ionization tendency can be sufficiently reduced. Therefore, a metal film having a small ionization tendency, such as copper, aluminum, iron, and nickel, can be efficiently formed.

When a metal film is formed from the metal film-forming composition, a large number of metal oxide-containing particles (A) are adhered to each other to form a film, so that a metal film having voids, that is, a porous metal film is generally obtained. . When the metal oxide-containing particles (A) having a large particle diameter are used, a more porous metal film having a large proportion of voids in the metal film can be obtained.
When the volume of the metal film is 100% by volume, the content ratio of the voids is usually 5 to 50% by volume.

<Method for forming metal film>
As described above, the metal film obtained from the metal film-forming composition is generally a film having voids. By filling the voids with metal, the metal film has no voids or a small content ratio of voids. Can be formed.

Examples of the method for filling the voids in the metal film with a metal include a method of filling the voids with a solution containing a metal element and generating metal from the liquid.
The solution containing a metal element is not particularly limited as long as it is a solution capable of generating a metal by a treatment such as heating. The metal element contained in the solution containing the metal element is usually the same metal element as the metal constituting the target metal film, and the metal-metal oxide composite particles (A1) and metal oxide particles (A2). ) Is the same metal element as the metal element contained in. For example, when the target metal film is a copper film, the solution containing a metal element is a solution containing a copper element. As the solution containing copper element, a copper formate solution is preferable because metal copper is easily generated.

  The solution containing a metal element may be a solution in which a metal complex of formic acid and ammonium formate are dissolved in a medium. With such a solution, metal is easily generated in the voids of the metal film.

The metal complex of formic acid has at least one metal element selected from copper, tin, palladium, cobalt, manganese, etc. (hereinafter referred to as “metal element (a)”) as a central atom and at least [HCOO as a ligand. ^- ] Is preferable. Examples of ligands other than [HCOO ⁻ ] include [NH ₃ ], [NH ₄ ⁺ ], [H ₂ NCOO ⁻ ], and [RCOO ⁻ ] (where R is a substituted or unsubstituted aliphatic hydrocarbon group. And the like. Of these, [NH ₃ ] having reducibility is preferable.

  The coordination number of the ligand coordinated to the central atom varies depending on the type of the metal element (a) constituting the central atom. For example, when the metal element (a) is copper and nickel, the coordination number The order is usually 4 or 6. When the metal complex of formic acid is a copper complex, the coordination number seems to be 6.

As the metal complex of formic acid, a metal complex of ammonium formate (such as a copper complex or a nickel complex) is preferable.
In addition, the solution containing a metal element is a mixture containing ammonium oxide and metal oxide (a) oxide or metal element (a) formate, which is a substance capable of forming a metal complex of formic acid. It may be a liquid. When the solution containing the metal element is such a mixed solution, metal is easily generated in the voids of the metal film.

  Examples of the metal element (a) oxide include copper (I) oxide, copper (II) oxide, cobalt (II) oxide, cobalt (III) oxide, tin (I) oxide, tin (II) oxide, palladium oxide ( II), manganese oxide (IV) and the like.

Examples of the formate of the metal element (a) include copper formate, nickel formate, cobalt formate, tin formate, palladium formate, and manganese formate.
If the solution containing the metal element is a solution in which a metal complex of formic acid or an oxide of the metal element (a) or a formate of the metal element (a) and ammonium formate are dissolved in a medium, the metal element is contained. The content of ammonium formate in the solution to be used is preferably more than 100 parts by mass and not more than 300 parts by mass, more preferably 110 to 250 parts by mass, and still more preferably 150 to 200 parts per 100 parts by mass of the metal complex of formic acid and the like. Part by mass.

  When the solution containing a metal element is a solution in which a metal complex of formic acid or an oxide of metal element (a) or a formate of metal element (a) and ammonium formate are dissolved in the medium, this medium is usually It is water. The content of water as a medium is preferably 20 to 20,000 parts by mass, more preferably 50 to 1,000 parts by mass, and still more preferably 100 to 400 parts by mass with respect to 100 parts by mass of a metal complex of formic acid or the like. It is.

  The medium may be a mixed medium of water and an organic compound dissolved in water (hereinafter referred to as “water-soluble organic compound”). In this case, the content of the water-soluble organic compound is preferably 0.5 to 100 parts by mass, more preferably 1 to 50 parts by mass, and further preferably 5 to 30 parts by mass with respect to 100 parts by mass of water.

  Examples of the water-soluble organic compound include monohydric alcohols such as methanol, ethanol and butanol; polyhydric alcohols; ethers such as tetrahydrofuran and diethyl ether. The said water-soluble organic compound may be used independently and may be used in combination of 2 or more type.

  There is no particular limitation on the method of filling the metal film-containing solution into the voids of the metal film. For example, a method of applying a metal element-containing solution to the metal film having voids and impregnating the liquid in the voids. Is mentioned.

There is no restriction | limiting in particular as a method to produce | generate a metal from the solution containing the metal element with which the space | gap of the metal film was filled, For example, the method of heating this metal film etc. can be mentioned.
The temperature at the time of heating is preferably 50 ° C to 300 ° C, more preferably 100 ° C to 280 ° C, and further preferably 120 ° C to 250 ° C. The heating time is usually 5 to 5000 minutes, preferably 10 to 120 minutes.

  The atmosphere during heating is preferably an atmosphere containing no oxygen gas, such as an inert gas atmosphere, from the viewpoint of suppressing oxidation of the formed metal film. From the viewpoint of productivity and the like, a preferable atmosphere is an atmosphere mainly containing nitrogen gas.

Such a process of filling the gap with a solution containing a metal element to generate a metal can be repeated a plurality of times as necessary.
By the treatment for filling the voids with the solution containing the metal element as described above to generate metal, a thick metal film having no voids or a small content ratio of voids can be formed. By this treatment, the content ratio of the voids in the metal film can be 10% by volume or less or substantially 0% by volume when the volume of the metal film is 100% by volume.

  Such a thick film having no voids can be suitably used for manufacturing bumps for joining a semiconductor and a substrate.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by this Example. In the examples and comparative examples, “part” represents “part by mass”.
Various measurements in Examples and Comparative Examples were performed by the following methods.

1. Various measuring methods (1) Measuring method of film thickness of metal film Measured with a scanning electron microscope manufactured by Hitachi High-Tech Co., Ltd.
(2) Method for Measuring Content Ratio of Voids in Metal Film A cross section of the metal film was photographed with a scanning electron microscope manufactured by Hitachi High-Tech Co., Ltd., the photograph was subjected to digital image processing, and the porosity was calculated according to the following equation.
Porosity (%) = (area of a region where no metal exists in the cross section of the metal film / area of the cross section of the metal film) × 100

2. Preparation of metal particle-containing composition [Example 1]
Fine electrolytic copper powder (product name “T-220” manufactured by Mitsui Kinzoku Co., Ltd.) was baked in an oven at 200 ° C. for 1 hour in the atmosphere, and a copper oxide film was formed on the surface portion. 20 parts of finely divided electrolytic copper powder after firing, 2 parts of dihydroxyacetone and 78 parts of glycerin are placed in a bead mill together with zirconia beads, the finely divided electrolytic copper powder after firing is pulverized, and copper-copper oxide composite particles, copper oxide particles and A metal film forming composition containing 20 parts of mixed particles of copper particles (particle diameter (D50): 0.2 μm), 2 parts of dihydroxyacetone and 78 parts of glycerin was prepared.

[Comparative Example 1]
Fine electrolytic copper powder (product name “T-220” manufactured by Mitsui Kinzoku Co., Ltd.) was baked in an oven at 200 ° C. for 1 hour in the atmosphere, and a copper oxide film was formed on the surface portion. 20 parts of finely divided electrolytic copper powder after firing and 80 parts of glycerin are put together with zirconia beads in a bead mill, and the finely divided electrolytic copper powder after firing is pulverized, and mixed particles of copper-copper oxide composite particles, copper oxide particles and copper particles A metal film forming composition containing 20 parts (particle diameter (D50): 0.2 μm) and 80 parts of glycerin was prepared.

3. Formation of porous metal film [Example 2]
The composition for forming a metal film of Example 1 was applied on a silicon wafer by spin coating, baked at 180 ° C. for 30 minutes in a nitrogen atmosphere, and then baked at 280 ° C. for 1 hour in a nitrogen atmosphere. A copper film having a film thickness of 25 μm and a void content of 20% by volume was formed. FIG. 1 shows an image obtained by observing the copper film with a scanning electron microscope. 1A is an image with a magnification of 500 times, and FIG. 1B is an image with a magnification of 5,000 times. When this copper film was confirmed to be conductive using a tester, the conductivity was confirmed.

[Comparative Example 2]
The composition for forming a metal film of Comparative Example 1 was applied onto a silicon wafer by spin coating, baked at 180 ° C. for 30 minutes in a nitrogen atmosphere, and then baked at 280 ° C. for 1 hour in a nitrogen atmosphere. could not.
Further, the metal particle-containing composition of Comparative Example 1 was applied onto a silicon wafer by spin coating, baked at 180 ° C. for 30 minutes in a nitrogen atmosphere, and then baked at 280 ° C. for 5 hours in a nitrogen atmosphere. Could not be formed.

4). Formation of a metal film using a solution containing a metal element [Example 3]
A solution containing a metal element prepared by dissolving 8 parts of ammonium formate and 5 parts of copper (I) oxide in 100 parts of water was applied to the porous metal film formed in Example 2. This metal film was heated at 200 ° C. for 15 minutes in a nitrogen stream. A copper film (thickness 25 μm) filled with copper metal produced from a solution containing a metal element was formed in the voids of the porous copper film. When this copper film was confirmed to be conductive using a tester, the conductivity was confirmed.
It was confirmed that the copper film can be formed without using the plating process by the metal film forming method of the present invention.

Claims (7)

  A portion including the surface portion is made of a metal oxide, and a portion other than the portion including the surface portion is selected from metal-metal oxide composite particles (A1) and metal oxide particles (A2) made of the metal. A composition for forming a metal film, comprising at least one metal oxide-containing particle (A), alditol (B) and alditol oxide (C).   The metal film-forming composition according to claim 1, wherein the alditol oxide (C) is the alditol (B) oxide.   The metal film-forming composition according to claim 1 or 2, wherein the alditol (B) is glycerin.   The composition for forming a metal film according to any one of claims 1 to 3, wherein the content of the oxide (C) of the alditol is 1 to 50 parts by mass with respect to 100 parts by mass of the alditol (B).   A metal film-containing solution is filled in a void of a metal film having a void obtained from the metal film-forming composition according to any one of claims 1 to 4, and a metal is added from the solution containing the metal element. A method of forming a metal film, characterized by comprising:   The method for forming a metal film according to claim 5, wherein the solution containing the metal element is a solution containing a copper element.   The method for forming a metal film according to claim 6, wherein the solution containing the copper element is a copper formate solution.