JP2006278936A - A manufacturing method of a substrate provided with a metal layer. - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a substrate formed with a metallization layer which can form the metallization layer low in volume resistance value on the substrate by heat treatment at a comparatively low temperature. <P>SOLUTION: In the manufacturing method of the substrate formed with the metallization layer, a primary particle diameter is 200 nm or less, and a dispersing element contains precursor particulates for forming the metallization layer which melt mutually by performing the heat treatment in a non-oxidization gas (A), and the dispersing element containing at least one kind of an additive selected from polyhydric alcohol and a polyether compound is given on the substrate, after forming a layer of the dispersing element on the substrate, it is heated in a non-oxidization gas atmosphere containing oxidant, and at the time of the heating, the additive in the dispersing element is oxidized by the oxidant, and an oxide skin is not formed on the surface of the metallization layer or the thickness of the oxide skin is controlled to be 300 nm or less simultaneously (B). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a substrate provided with a metal layer, for example, a metal thin film layer, an electric wiring layer, an electric circuit layer, and the like.

Conventionally, as a method for forming a metal layer, for example, a metal thin film layer on a substrate, a vacuum deposition method, a sputtering method, a CVD method, a plating method, a metal paste method, and the like are known. The vacuum deposition method, the sputtering method, and the CVD method all require an expensive vacuum device, and all have a problem that the film forming speed is low.
According to the plating method, it is possible to form a metal film on a conductive substrate relatively easily. However, when forming on an insulating substrate, it is necessary to form a conductive layer first. Therefore, there is a problem that the process becomes complicated. In addition, since the plating method uses a reaction in a solution, a large amount of waste liquid is produced as a by-product, and there is a problem that this waste liquid treatment requires a lot of labor and cost.

The metal paste method is a method of applying a solution in which a metal filler is dispersed on a substrate and heat-treating to obtain a metal thin film, and does not require a special device such as a vacuum device, and the process is simple. However, in order to melt the metal filler, a high temperature of 1000 ° C. or higher is usually required. Therefore, the base material is limited to a heat-resistant base material such as a ceramic base material, and there is a problem that the base material is damaged by heat or the base material is easily damaged by residual stress generated by heating.
A technique for reducing the firing temperature of the metal paste by reducing the particle size of the metal filler is well known. For example, Patent Document 1 discloses a technique using a dispersion liquid in which metal fine particles having a particle size of 100 nm or less are dispersed. A method of forming a thin film is disclosed. However, the method for producing metal particles of 100 nm or less required here is a method for rapidly cooling metal vapor volatilized in a reduced-pressure atmosphere, so that mass production is difficult, and therefore the cost of the metal filler is very high. Has the problem.

  A method of forming a metal thin film using a metal oxide paste in which a metal oxide filler is dispersed is also known. Patent Document 2 discloses a method of heating a metal oxide paste containing a crystalline polymer and containing cuprous oxide fine particles having a particle size of 300 nm or less and decomposing the crystalline polymer to obtain a metal thin film. It is disclosed. However, in this method, it is necessary to disperse a metal oxide of 300 nm or less in the crystalline polymer in advance, and in addition to requiring a great deal of effort, in order to decompose the crystalline polymer, a reduced pressure atmosphere In this case, a high temperature of 400 ° C. to 900 ° C. is required. Therefore, since the base material which can be used requires the heat resistance more than the temperature, there exists a problem that a base material has a restriction | limiting.

As described above, the method of obtaining a metal thin film by applying a dispersion liquid in which a metal or metal oxide filler is dispersed on a substrate and further heat-treating it is a low process cost method. At present, there are problems such as high cost and high heat treatment temperature, and it has not been put into practical use. In particular, it is difficult to apply as a metal thin film forming method on a resin base material used in the consumer field.
As a method of manufacturing a metal thin film that solves these problems, the present applicant has already applied a dispersion in which an inexpensive metal oxide filler is dispersed on a substrate, and then applied the metal thin film by heat treatment at a relatively low temperature. The method of obtaining is disclosed (Patent Document 3). Although it is possible to easily form a thin metal film such as copper on the substrate by this technique, there is a demand for further reduction in resistance of the metal thin film.

Similar problems exist not only when the metal thin film layer is formed, but also when electrical wiring, electrical circuits, etc. are formed on the substrate.
Japanese Patent No. 2561537 Japanese Patent Laid-Open No. 5-98195 WO03 / 051562 pamphlet

  An object of the present invention is to provide a method for producing a substrate provided with a metal layer having a low volume resistance value, for example, a metal thin film layer, an electric wiring layer, an electric circuit layer, etc., by heat treatment at a relatively low temperature. That is.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has completed the present invention.
That is, the present invention is as follows.
1. (A) Precursor fine particles having a primary particle diameter of 200 nm or less and fused together to form a metal layer by heat treatment in a non-oxidizing gas; (B) polyhydric alcohol and polyether A dispersion containing at least one additive selected from a compound is applied on a substrate to form a layer of the dispersion on the substrate, and then heated in a non-oxidizing gas atmosphere containing an oxidizing agent. In the method of manufacturing a substrate having a metal layer, the additive in the dispersion is oxidized by an oxidizing agent during the heating, and an oxide film is not formed on the surface of the metal layer. A method for manufacturing a substrate provided with a metal layer, wherein the thickness is controlled to 300 nm or less.
2. 2. The method for producing a substrate provided with the metal layer according to 1 above, wherein the oxidizing agent is oxygen or water.
3. 3. The method for producing a substrate having a metal layer according to 2 above, wherein the concentration of oxygen in the non-oxidizing gas is 30 to 500 ppm.
4). 3. The method for producing a substrate having a metal layer according to 2 above, wherein the volume ratio of water in the non-oxidizing gas is 0.01 to 10%.
5. 2. The method for producing a substrate provided with the metal layer according to 1 above, wherein the non-oxidizing gas contains a reducing gas.
6). 2. The method for producing a substrate having a metal layer according to 1 above, wherein the polyether compound is an aliphatic polyether compound having a linear or cyclic oxyalkylene group having 2 to 6 carbon atoms as a repeating unit. .
7). 7. The method for producing a substrate having a metal layer as described in 6 above, wherein the aliphatic polyether compound is a linear aliphatic polyether compound having a number average molecular weight of 150 to 600.
8). 2. The method for producing a substrate provided with the metal layer according to 1 above, wherein the precursor fine particles for forming the metal layer are metal oxide fine particles.
9. 9. The method for producing a substrate provided with the metal layer according to 8 above, wherein the metal oxide is copper oxide.
10. 10. The method for producing a substrate provided with the metal layer as described in 9 above, wherein the copper oxide is cuprous oxide.
11. The manufacturing method of the board | substrate provided with the metal layer of said 1 whose heating temperature is 50 degreeC or more and less than 500 degreeC.

  According to the present invention, a substrate provided with a metal layer having a low volume resistance, for example, a metal thin film layer, an electric wiring layer, an electric circuit layer, or the like can be manufactured by heat treatment at a relatively low temperature.

The present invention is described in detail below.
In the present invention, the “metal layer” is a continuous layer formed by bonding metal particles having a primary particle diameter of 200 nm or less to each other, and is observed at a magnification of 30,000 times using an electron microscope. (1) a layer in which the boundary between particles disappears to form a continuous layer, (2) a layer in which the boundary between metal particles is observed over a part or all of the periphery of the particle, or (3) both Refers to a layer with a mixture of
The shape of the “metal layer” is arbitrary, and examples thereof include a planar shape, a straight shape, a curved shape, a circular shape, a dot shape, an island shape, and combinations thereof. Therefore, the metal layer is formed by bonding metal particles to each other to form a planar shape, a linear shape, a curved shape, a circular shape, a dot shape, an island shape, or the like. As a typical metal layer, a metal thin film, an electric wiring formed by combining with other shapes around a straight line, an electric circuit, and the like can be given.

The dispersion used in the method for producing a substrate having a metal layer according to the present invention has a primary particle diameter of 200 nm or less, and is heat-treated in a non-oxidizing gas so as to be fused together to form a metal layer. Precursor fine particles (hereinafter simply referred to as precursor fine particles) and an additive composed of a polyhydric alcohol and / or a polyether compound are included.
The precursor fine particles are formed by applying a dispersion containing the precursor fine particles on the substrate to form a layer of the dispersion, and then heat-treating the fine particles to each other to form a metal layer.
The “dispersion layer” is formed in a shape corresponding to the target metal layer. That is, the dispersion layer is formed so as to obtain a target metal layer when heat-treated according to the present invention. Therefore, it is preferable that the correspondence relationship between the layer of the dispersion and the metal layer is grasped in advance by a preliminary test.

The precursor fine particles have a primary particle diameter of 200 nm or less, preferably 100 nm or less, more preferably 30 nm or less. When the primary particle diameter of the precursor fine particles is larger than 200 nm, a metal layer in which the fine particles are bonded to each other by heat treatment cannot be obtained. From the viewpoint of the viscosity and handleability of the dispersion, the primary particle size is preferably 1 nm or more.
The precursor fine particles used in the present invention are not limited as long as the metal layer is formed by heat treatment, and preferably include metal fine particles, metal oxide fine particles, and metal hydroxide fine particles.
As the metal fine particles, copper fine particles formed by a method such as a wet method or a gas evaporation method are preferable. From the viewpoint of the production cost of the fine particles, copper fine particles produced by a wet method are preferred.

Examples of the metal hydroxide fine particles include fine particles composed of compounds such as copper hydroxide, nickel hydroxide, and cobalt hydroxide. Among these, copper hydroxide fine particles that form a metal layer made of copper are preferable.
Metal oxide fine particles are particularly preferable from the viewpoints of dispersibility in a dispersion medium and easy formation of a metal layer by heat treatment. Examples of the metal oxide fine particles include copper oxide, silver oxide, palladium oxide, nickel oxide and the like. Especially, the copper oxide which forms copper by heat processing is preferable. As the copper oxide, any of cuprous oxide, cupric oxide, and other copper oxides having an oxidation number can be used. Cuprous oxide fine particles are particularly preferred because they can be easily reduced.
As the precursor fine particles, commercially available products may be used, or the precursor fine particles may be synthesized using a known synthesis method. For example, as a method for synthesizing cuprous oxide ultrafine particles having a primary particle diameter of less than 100 nm, a method of synthesizing acetylacetonato copper complex by heating at about 200 ° C. in a polyol solvent is known (Angevante Chemi International Edition). No. 40, Volume 2, p.359, 2001).

The state of the dispersion used in the present invention is not limited to liquids, solids, fluids and the like. The mass of the precursor fine particles in the dispersion is not limited, but is preferably 5% or more and less than 90%, more preferably 20% or more and less than 80% with respect to the total amount of the dispersion.
The method for applying the dispersion on the substrate can be appropriately selected according to the shape of the target metal layer.
In the case of a liquid dispersion having fluidity, first, the dispersion is applied on the substrate. As the application method, a general method used when applying the dispersion to the substrate can be used. For example, a screen printing method, a dip coating method, a spray coating method, a spin coating method, an ink jet method, a dispensing method, Examples thereof include a bar coating method, a gravure coating method, and a contact printing method.
When a dispersion is applied to the entire surface of a relatively large substrate surface, a dip coating method, a spray coating method, a spin coating method, a bar coating method, a gravure coating method, or the like is particularly preferably used.

In the case where the dispersion is applied to the circuit shape on the substrate, a dispensing method, an inkjet method, and a screen printing method are particularly preferable. Among these, when the dispersion has a high viscosity, a screen printing method or the like is preferable, and when the dispersion has a low viscosity, an inkjet method or the like can be suitably used.
In the case where the dispersion is a thin film solid, a structure in which the dispersion is laminated on the substrate can be formed by pasting the film on the substrate.
After the dispersion is applied on the substrate, the substrate is heat-treated to form a metal layer on the substrate. When the applied dispersion is susceptible to oxidation or the like by atmospheric oxygen or moisture, it is preferably applied on the substrate in an inert atmosphere or the like.

In the present invention, a dispersion layer formed on a substrate is heated in a non-oxidizing gas atmosphere to convert precursor fine particles for forming a metal layer into a metal layer. In addition, the additive in the dispersion is oxidized with the oxidizing agent, and the oxide film is not formed on the surface of the metal layer, or the thickness of the oxide film is controlled to 300 nm or less.
The non-oxidizing gas is a gas that does not contain an oxidizing gas such as oxygen, and typically includes an inert gas and a reducing gas. Examples of the inert gas include argon, helium, neon, nitrogen and the like. Examples of the reducing gas include hydrogen, carbon monoxide, and ammonia. From the viewpoint of ease of handling, hydrogen is particularly preferable. A mixed gas of an inert gas and a reducing gas can also be used.

According to the present invention, by including an oxidant in the non-oxidizing gas, the oxidative decomposition of the additive in the dispersion is promoted during the heat treatment, and the volume resistance value of the metal layer to be generated is reduced. It is possible to prevent the resistance from increasing due to oxidation deep into the inner layer of the layer. However, the thickness of the oxide film needs to be controlled to 300 nm or less. If the thickness of the oxide film exceeds 300 nm, the oxide film itself becomes brittle and easily peels off.
When an oxide film is formed on the surface of the metal layer, the oxide film serves as a protective layer for the metal layer, and when the metal layer is covered with an insulating interlayer film or the like for applications such as multilayer circuit boards, the oxide film It has an effect of increasing the adhesive strength between the metal layer and the insulating film. In the case where an oxide film is not formed on the surface of the metal layer, there is an effect that, for example, when the metal layer surface is plated or soldered, the adhesive strength with the plated layer and the solder joint strength are improved.

The necessary conditions for heating in a non-oxidizing gas containing an oxidizing agent are that the precursor fine particles can be reduced to form a metal layer, and an oxide film is not formed on the surface of the metal layer, or the thickness of the oxide film is 300 nm or less. It can be controlled.
Therefore, it is preferable to set the kind of non-oxidizing gas, the heating temperature, the heating time, the kind of oxidizing agent, and the ratio of oxidizing agent in advance through preliminary experiments so that the above-mentioned conditions can be achieved.
The reducing gas has a positive effect such as suppressing oxidation of the metal layer when the dispersion containing the precursor fine particles is heated to form the metal layer, and there is no oxide film on the surface of the layer. It is particularly preferable when forming a metal layer.

The thickness of the oxide film is controlled by adjusting the amount of oxidizing agent, heating time, and the like. In order to form a relatively thick oxide film, the amount of the oxidizing agent is increased and the heat treatment time is lengthened. Moreover, an oxide film can be formed in a short time, so that heating temperature is made high. When an oxide film is not formed, it is effective to use a reducing gas in combination, or to reduce the amount of oxidant and shorten the heating time.
Mixing and using a plurality of non-oxidizing gases, for example, reducing gas and inert gas, also has an effect of suppressing oxidation of the metal layer. In this case, the preferred reducing gas ratio in the mixed gas is 0.1% or more by volume, and more preferably 0.5% or more by volume. If the addition amount is less than 0.1%, the effect of inhibiting oxidation may not be sufficient.

A preferable heat treatment temperature is 50 ° C. or higher and 500 ° C. or lower, more preferably 100 ° C. or higher and 350 ° C. or lower. When the precursor fine particles are reduced at a temperature lower than 50 ° C., the storage stability of the metal oxide ultrafine particle dispersion may be easily lowered. When the temperature is higher than 500 ° C., the substrate is likely to be damaged. There is.
The heating time is affected by the type of metal layer precursor fine particles and the dispersion composition, but is preferably about 10 to 60 minutes. Although heat treatment can be performed by batch processing, a more preferable heat treatment method is to transport the substrate by chain transportation or the like while controlling the oxygen concentration using a commercially available nitrogen reflow device from the viewpoint of productivity. It is the method of carrying out continuous heat treatment.

The oxidizing agent used in the present invention is not limited as long as the additive in the dispersion can be oxidatively decomposed, but particularly preferable oxidizing agents are oxygen and moisture from the viewpoint of easy addition to the non-oxidizing gas.
When oxygen is added to the non-oxidizing gas, the preferable oxygen concentration is 30 to 500 ppm. When the oxygen concentration exceeds 500 ppm, the obtained metal layer may be oxidized up to the inner layer, and in this case, the volume resistance value of the obtained metal layer may increase. When the oxygen concentration is less than 30 ppm, the decomposition promoting effect of the polyhydric alcohol and / or polyether compound contained in the dispersion may be reduced.

As a method of adding oxygen to the non-oxidizing gas so as to have a predetermined concentration, it may be controlled by quantitatively mixing oxygen gas or air and non-oxidizing gas using a mass flow controller or the like. A standard gas in which oxygen is added to a predetermined oxygen concentration may be purchased and used.
When water is added to the non-oxidizing gas, the preferable water concentration is 0.01 to 10%. When the moisture concentration exceeds 10%, the metal oxide ultrafine particles in the metal oxide dispersion coated on the substrate may cause aggregation. When the water concentration is less than 0.01%, the effect of promoting the decomposition of the polyhydric alcohol and / or polyether compound contained in the dispersion may be reduced.
As a method of adding moisture to the non-oxidizing gas, for example, a method of generating a predetermined amount of moisture by placing a water vapor generating device in the non-oxidizing gas flow path can be used.

The dispersion of precursor fine particles used in the present invention contains a polyhydric alcohol and / or a polyether compound as a constituent component in addition to the precursor fine particles. When the dispersion contains a polyhydric alcohol and / or a polyether compound, a heat treatment is performed to obtain a metal layer from the precursor fine particles, which is preferable because a uniform metal layer is obtained and moldability is improved.
The reason why a metal layer having a low volume resistivity is formed by heat-treating the substrate on which such a dispersion layer is formed according to the present invention is not necessarily clear, One of the reasons is considered to be that the decomposition of the polyhydric alcohol and / or the polyether compound, which is an additive, is accelerated, and the organic components remaining in the metal layer are reduced.

  The polyhydric alcohol is a compound having a plurality of hydroxyl groups in the molecule. The polyhydric alcohol has a moderately high boiling point and is not easily volatilized. Use of the polyhydric alcohol is preferable because drying is suppressed and a uniform metal layer can be formed when the dispersion is applied to the substrate. Among the polyhydric alcohols, polyhydric alcohols having 10 or less carbon atoms are preferred, and among them, low viscosity, such as ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1 , 2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, pentanediol, hexanediol, octanediol and the like are particularly preferable. These polyhydric alcohols may be used alone or in combination.

The reason why a uniform metal layer is formed by using a polyhydric alcohol is not necessarily clear, but when the precursor fine particles are metal oxide fine particles or metal hydroxide fine particles, the polyhydric alcohol is a hydroxyl group on the surface of the fine particles. It is thought that it has a function of protecting the particle surface by interacting with and suppressing aggregation between particles. Polyhydric alcohol also has the effect of reducing metal oxide fine particles or metal hydroxide fine particles.
When the dispersion contains a polyether compound, in addition to the effect of forming a uniform metal layer, the resistance value of the metal layer obtained by heat treatment is reduced. The reason is considered that the polyether compound serves as an easily decomposable and easily burnable binder to prevent local granulation of the precursor fine particles during the heat treatment.

Preferred as the polyether compound is an aliphatic polyether compound having a linear and cyclic oxyalkylene group having 2 to 6 carbon atoms as a repeating unit, and particularly preferred is a straight chain having a number average molecular weight of 150 to 600. In the form of an aliphatic polyether compound.
When the molecular weight of the linear aliphatic polyether compound is within this range, a more uniform metal layer is formed, and on the other hand, it is easily decomposed and burned, so that the volume resistance value of the obtained metal layer tends to decrease. If the molecular weight is less than 150, the uniformity of the layer when the metal layer is obtained by heat treatment tends to decrease, and if the molecular weight exceeds 600, the volume resistance value of the resulting metal layer tends to increase.

The linear aliphatic polyether compound may be a homopolymer having one type of repeating unit, or may be a copolymer or block copolymer having two or more types of repeating units.
Specifically, in addition to polyether homopolymers such as polyethylene glycol, polypropylene glycol, polybutylene glycol, ethylene glycol / propylene glycol, ethylene glycol / butylene glycol binary copolymer, ethylene glycol / propylene glycol / ethylene glycol, Examples include, but are not limited to, linear ternary copolymers such as propylene glycol / ethylene glycol / propylene glycol and ethylene glycol / butylene glycol / ethylene glycol. As block copolymers, binary block copolymers such as polyethylene glycol polypropylene glycol and polyethylene glycol polybutylene glycol, and linear chains such as polyethylene glycol polypropylene glycol polyethylene glycol, polypropylene glycol polyethylene glycol polypropylene glycol, polyethylene glycol polybutylene glycol polyethylene glycol, etc. And polyether block copolymers such as ternary block copolymers.

The structure of the terminal of the linear aliphatic polyether compound is not limited as long as it does not adversely affect the dispersibility of the fine particles and the solubility in the dispersion medium, but if at least one terminal is an alkyl group, This is preferable because the decomposition and burn-out property of the polyether compound is improved and the volume resistance value of the resulting metal layer is lowered. If the length of the alkyl group is too long, the dispersibility of the fine particles is hindered and the viscosity of the dispersion tends to increase. Therefore, the length of the alkyl group is preferably 1 to 4 carbon atoms.
The reason why the decomposition and burn-out property during heat treatment is improved by at least one terminal being an alkyl group is not clear, but hydrogen bonding between the fine particles and the polyether compound or between the polyether compound and the polyether compound It is surmised that the weakening of the interaction force based on the above is contributing.

A particularly preferable structure of the linear aliphatic polyether compound is a structure in which one terminal is an alkyl group and the other terminal is a hydroxyl group, and examples thereof include polyethylene glycol methyl ether and polypropylene glycol methyl ether. .
Although there is no restriction | limiting in the ratio of the precursor microparticles | fine-particles in a dispersion, It is mass% with respect to a dispersion total amount, Preferably it is 5-90%, More preferably, it is 20-80%. When the mass of the fine particles in the dispersion is in these ranges, it is preferable because the fine particles are dispersed and a metal layer having an appropriate thickness can be obtained by a single coating / heating treatment.
The ratio of the polyhydric alcohol in the dispersion is mass% with respect to the total amount of the dispersion, preferably 5 to 70%, more preferably 10 to 50%.

The ratio of the polyether compound in the dispersion is mass%, preferably 0.1 to 70%, more preferably 1 to 50%, based on the total amount of the dispersion. When the addition amount of the polyether compound is less than 0.1%, the denseness of the resulting metal layer may be lowered or the adhesion to the substrate may be reduced, while the addition of the polyether compound If the amount exceeds 70%, the viscosity of the dispersion may increase.
The preferred mass ratio of the polyether compound to the precursor fine particles varies depending on the kind of fine particles used and the kind of the polyether compound, but is usually in the range of 0.01 to 10. Within this range, the denseness of the resulting metal layer is improved and the volume resistance value is further reduced.

In this invention, you may add additives, such as an antifoamer, a leveling agent, a viscosity modifier, a stabilizer, to the said dispersion as needed.
The dispersion of precursor fine particles used in the present invention may further contain a dispersion medium in addition to the precursor fine particles and the polyhydric alcohol and / or the polyether compound. The dispersion medium is not particularly limited as long as it can uniformly dissolve and disperse the metal layer precursor fine particles having a primary particle diameter of 200 nm or less and the polyhydric alcohol and / or the polyether compound. Examples of the organic dispersion medium include alcohol, ether, ester, amide, sulfoxide and the like. In use, a dispersible one is appropriately selected from these. These dispersion media may be used alone or in combination.

As a method for dispersing the precursor fine particles, the polyhydric alcohol and / or the polyether compound and, if necessary, the dispersion medium in a liquid state, a general method for dispersing the powder in the liquid can be used. For example, after adding precursor fine particles, a polyhydric alcohol and / or a polyether compound, and a dispersion medium as necessary, dispersion may be performed by an ultrasonic method, a mixer method, a three-roll method, or a ball mill method. It is also possible to perform dispersion by combining a plurality of these dispersion means. These dispersion treatments may be performed at room temperature, or may be performed by heating in order to reduce the viscosity of the dispersion.
As the substrate used in the present invention, both inorganic and organic substrates can be used. Examples of the inorganic substrate include a metal plate, a glass plate, and a ceramic substrate such as ITO (indium tin oxide). The organic substrate is not limited as long as it is not thermally damaged at the heat treatment temperature of the metal oxide dispersion. For example, a substrate such as polyimide, polyethylene terephthalate (PET), aramid, or epoxy can be used.

A substrate-metal thin film laminate obtained by applying a dispersion on a substrate in the form of a solid film and heat treatment is suitably used for applications such as a metal foil with a resin in the mounting field. By controlling the thickness of the dispersion applied / laminated on the substrate, it is possible to arbitrarily control the film thickness of the resulting metal layer, especially the ultrathin metal required when forming fine circuits This has the advantage that the layer can be easily formed.
In addition, by applying the dispersion in advance to the pattern shape of the electric circuit and heat treatment, it is possible to directly form metal wiring on the substrate without a photolithography process, and there is an advantage that the wiring substrate can be made at low cost. It is particularly preferably used for this wiring direct drawing application. Examples of direct drawing of metal wiring include formation of bus electrodes and address electrodes on a glass substrate, wiring circuit formation on a resin or ceramic substrate, and the like.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
The primary particle size of the precursor fine particles was obtained by observing the surface of a dispersion of metal oxide ultrafine particles on a slide glass using a scanning electron microscope (S-4700) manufactured by Hitachi. taking measurement. The volume resistivity of the obtained metal thin film is measured using a low resistivity meter Lorester GP (manufactured by Mitsubishi Chemical Corporation).
The film thickness of the oxide layer on the surface of the metal layer was determined by performing Auger analysis in the depth direction on the obtained metal layer (PHI680 manufactured by ULVAC-PHI, argon ion sputtering), measuring the oxygen concentration distribution, and providing the highest oxygen intensity. Read the sputtering time at which the intensity is ½. A sputtering rate of the oxide film is separately obtained in advance, and the film thickness of the oxide film is calculated by multiplying by the sputtering time and the sputtering rate.

[Example 1]
Add 8 g of anhydrous copper acetate (manufactured by Wako Pure Chemical Industries, Ltd.) to 60 ml of purified water, add hydrazine monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) while stirring at 25 ° C., and stir for another 10 minutes. Cuprous oxide ultrafine particles having a primary particle size distribution of 15 to 25 nm were obtained. 0.30 g of diethylene glycol and 0.15 g of polyethylene glycol methyl ether (number average molecular weight 550, manufactured by NOF Corporation) are added to 0.30 g of the cuprous oxide fine particles, and subjected to ultrasonic dispersion to disperse cuprous oxide. I adjusted my body.
The dispersion was applied on a slide glass so as to have a length of 5 cm, a width of 1 cm, and a thickness of 20 μm, and then the slide glass was placed on a hot plate placed in a glove box. While flowing nitrogen gas adjusted to an oxygen concentration of 150 ppm into the glove box, the temperature of the hot plate was raised from room temperature to 350 ° C., held at this temperature for 10 minutes, the thickness was 4 μm, and the volume resistivity was 2. A copper thin film of 7 × 10 ⁻⁶ Ωcm was obtained. The film thickness of the oxide film on the surface of the copper thin film was 150 nm.

[Examples 2 to 7]
Using the same cuprous oxide dispersion as in Example 1, firing was performed using nitrogen gas with adjusted oxygen or moisture concentration, and the volume resistance value of the obtained copper thin film was measured. The results are shown in Table 1.
[Example 8]
To 0.30 g of cuprous oxide fine particles prepared by the same method as in Example 1, 0.30 g of diethylene glycol and 0.35 g of polyethylene glycol methyl ether (number average molecular weight 200, manufactured by NOF Corporation) were added and subjected to ultrasonic dispersion. Then, a cuprous oxide dispersion was prepared. Baking was performed in the same manner as in Example 1 to obtain a copper film having a volume resistivity of 2.7 × 10 ⁻⁶ Ωcm. The film thickness of the oxide film on the surface of the copper thin film was 140 nm.

[Example 9]
To 0.30 g of the cuprous oxide fine particles obtained in Example 1, 0.20 g of ethylene glycol and 0.25 g of polyethylene glycol methyl ether (number average molecular weight 550, manufactured by NOF Corporation) were added and subjected to ultrasonic dispersion. After preparing the cuprous oxide dispersion, the dispersion was packed into a dispenser syringe having a syringe with an inner diameter of 100 μm at the tip. Next, a glass substrate was placed on the sample stage of the dispenser robot. At the same time that air pressure is applied to the syringe, the tip of the syringe is linearly moved to give a length of 5 cm, a width of 120 μm, and a thickness of 50 μm, and then the glass plate is placed on a hot plate placed in a glove box. It was. Heating was performed while raising the temperature of the hot plate from room temperature to 350 ° C. while flowing nitrogen gas adjusted to an oxygen concentration of 100 ppm into the glove box, and the thickness was 5 μm and the volume resistivity was 2.8 × 10 ^−. A copper wiring of ⁶ Ωcm was obtained. The film thickness of the oxide film on the surface of the copper thin film was 120 nm.

[Comparative Example 1]
The same cuprous oxide dispersion as in Example 1 was applied onto the substrate in the same manner as in Example 1, and calcination was performed using nitrogen gas adjusted to have an oxygen concentration of less than 10 ppm and a water content of less than 0.01%. As a result, the volume resistance value was as high as 8.0 × 10 ⁻⁶ Ωcm.

  A substrate-metal thin film laminate obtained by applying a dispersion on a substrate in the form of a solid film and subjecting it to heat treatment is suitably used for applications such as a metal foil with resin in the mounting field. By applying the dispersion to the pattern shape of the electric circuit in advance and subjecting the dispersion to heat treatment, it is possible to directly form metal wiring on the substrate without a photolithography process.

Claims (11)

  (A) Precursor fine particles having a primary particle diameter of 200 nm or less and fused together to form a metal layer by heat treatment in a non-oxidizing gas; (B) polyhydric alcohol and polyether A dispersion containing at least one additive selected from a compound is applied on a substrate to form a layer of the dispersion on the substrate, and then heated in a non-oxidizing gas atmosphere containing an oxidizing agent. In the method of manufacturing a substrate having a metal layer, the additive in the dispersion is oxidized by an oxidizing agent during the heating, and an oxide film is not formed on the surface of the metal layer. A method for manufacturing a substrate provided with a metal layer, wherein the thickness is controlled to 300 nm or less.   The method for producing a substrate having a metal layer according to claim 1, wherein the oxidizing agent is oxygen or water.   The method for producing a substrate having a metal layer according to claim 2, wherein the concentration of oxygen in the non-oxidizing gas is 30 to 500 ppm.   The method for producing a substrate having a metal layer according to claim 2, wherein the volume ratio of water in the non-oxidizing gas is 0.01 to 10%.   The method for manufacturing a substrate having a metal layer according to claim 1, wherein the non-oxidizing gas contains a reducing gas.   2. The production of a substrate having a metal layer according to claim 1, wherein the polyether compound is an aliphatic polyether compound having a linear or cyclic oxyalkylene group having 2 to 6 carbon atoms as a repeating unit. Method.   7. The method for producing a substrate having a metal layer according to claim 6, wherein the aliphatic polyether compound is a linear aliphatic polyether compound having a number average molecular weight of 150 to 600.   2. The method for producing a substrate having a metal layer according to claim 1, wherein the precursor fine particles for forming the metal layer are metal oxide fine particles.   9. The method for producing a substrate having a metal layer according to claim 8, wherein the metal oxide is copper oxide.   The method for manufacturing a substrate having a metal layer according to claim 9, wherein the copper oxide is cuprous oxide.   The manufacturing method of the board | substrate provided with the metal layer of Claim 1 whose heating temperature is 50 degreeC or more and less than 500 degreeC.