JP2022122700A - Method and apparatus for forming metal film, and electronic product using metal film - Google Patents

Abstract

To solve the problem that a method capable of obtaining a metal film by conventionally using titanium oxide as a reducer to deposit metal is noticed as one capable of directly forming a metal wiring on the surface of glass, etc., however when forming the titanium oxide on a treated surface by a method, such as colloid and sputtering, the titanium oxide can be formed on a flat treated surface but cannot be easily formed on the inner wall surface of a through hole.SOLUTION: A metal film formed by a method for forming a metal film comprising: a step of forming a coexistence region between a metal ion region where metal ions existing in a liquid phase on the surface to be treated of an object to be treated and a liquid phase deposition material region where a liquid phase deposition material exists; and a reduction step of reducing the metal ions to modify the coexistence region to the metal film can be formed even in the inner wall of a through hole.SELECTED DRAWING: Figure 1

Description

The present invention provides a method for forming a metal film on an insulating substrate such as a resin substrate, a ceramic substrate, a glass substrate, or a silicon substrate, or a metal such as copper, aluminum, or silver, a forming apparatus, and the metal film. Regarding electronic products.

Conventionally, a plating method is adopted for forming a metal film on an object to be processed. In this method, first, a metal layer is formed on the surface of the object to be processed by electroless plating, and then the metal thickness is increased by electrolytic plating.

When performing electroless plating, it is necessary to roughen the surface of the object to be treated in advance by means of wet etching or the like to impart fine irregularities, and then to support a catalytic metal such as palladium on the surface of the object to be treated. In electroless plating, a catalyst metal supported on the surface of the object to be treated serves as a nucleus, and a metal film is formed thereon.

On the other hand, as a technique for forming a metal film without roughening the object to be processed, a method for forming a metal film using a photocatalytic reaction of titanium oxide is known. In this method, a titanium oxide layer is formed on the surface of the object to be treated, and then the metal ions are reduced using the electrons generated from the titanium oxide by contacting with a metal ion solution under ultraviolet irradiation to reduce the titanium oxide. deposit on inclusions.

The titanium oxide layer is formed by modifying the surface of the object to be treated with a silane coupling agent, then coating and immersing a titanium oxide colloidal solution to support the titanium oxide-containing layer on the object to be treated. A method of applying a metal ion solution and irradiating with ultraviolet rays (Patent Document 1) and a method of using a sputtering method (Non-Patent Document 1) are known.

Japanese Patent No. 4508680

Toyama Prefectural Industrial Technology Center Research Report No.25 (2011)

As in Patent Document 1 and Non-Patent Document 1, the method of obtaining a metal film by precipitating a metal by utilizing the reducing power obtained by irradiating titanium oxide with UV is applied to glass, resin, ceramics, silicon. It is attracting attention as a method of forming metal wiring directly on the surface of such as. Advantages include no use of harmful chemicals and no need for surface roughening for adhesion to the treated surface.

However, although it is possible to form a flat surface by forming titanium oxide on the surface to be processed by a method such as colloidal or sputtering, it is not easy to form the inner wall surface of the through hole.

In addition, when titanium oxide is formed as a colloid, it is adsorbed on the surface of the object treated with a silane coupling agent, so the thickness of the titanium oxide film cannot be controlled, and therefore the film uniformity of the metal film is stabilized. could not be secured.

In addition, since the titanium oxide layer is supported on the object to be treated by physical adsorption due to the roughness of the silane coupling agent molecules, it is easily peeled off from the surface of the object to be treated, and the metal film finally obtained is There was a problem that it was easy to peel.

In addition, since the silane coupling agent is used, the silane coupling agent decomposes in the firing process, which is indispensable for improving the performance of titanium oxide as a photocatalyst, so there is a problem that the temperature in the firing process cannot be increased.

In addition, since the titanium oxide layer is supported on the object to be treated by physical adsorption due to the roughness of the silane coupling agent molecules, the flatness of the titanium oxide-containing layer is low. The flatness of the metal film is also low, so in high-frequency fields such as fifth-generation mobile communication systems (5G), in-vehicle millimeter-wave radar antennas, interfaces such as MHL3.0 and Thunderbolt used for high-speed transmission, conductors due to the skin effect There is a problem that a loss occurs, and as a result, the transmission loss increases remarkably.

In addition, although the formation of a titanium oxide-containing layer by a sputtering method has very high adhesion and flatness, it is a process of depositing titanium oxide in a dry environment, so there is a problem that the production cost is very high.

As a result of extensive studies, the present inventors have found that the above problem can be solved by coexisting metal ions together with a liquid phase deposition material formed using a liquid phase deposition method (hereinafter also referred to as "LPD method"). found to be resolved.

Specifically, the method for forming a metal film according to the present invention includes:
A step of forming a coexisting region of a metal ion region in which metal ions are present in a liquid phase and a liquid phase deposition material region in which a liquid phase deposition material is present on the surface of an object to be processed;
The method is characterized by including a reduction treatment step of reducing the metal ions and modifying the coexisting region into a metal film on the surface to be treated.

In the method for forming a metal film according to the present invention, the liquid phase deposition material region is composed of a hexafluoro complex ion solution capable of depositing a solid from the liquid phase and a metal ion solution, and the coexisting region is a liquid composed of a fluoro complex ion solution. Since the phase deposition material region and the metal ion region composed of the metal ions in the metal ion solution are formed, both regions are supplied onto the surface to be treated in a liquid phase. Therefore, even in a constricted portion such as a through hole, a coexisting region can be formed.

As a result, it is possible to uniformly form a coexisting region containing the liquid-phase deposition material and the metal ions on the surface of the object to be processed, including through holes. By performing a reduction treatment on this co-existing region, the co-existing region can be reduced and reformed into a metal film, so that a metal film can be formed on the surface to be treated including the through-holes.

In addition, since the liquid phase deposition material region formed by the present invention is formed on the surface of the object to be treated by chemical bonding, the finally obtained metal film is difficult to peel off from the surface to be treated. .

Also, the coexisting region formed by the present invention is formed directly on the surface of the object to be treated without intervening a coupling agent or the like. Therefore, the temperature of the baking process can be increased without considering the decomposition of the coupling agent, and the reducing power of the reduction treatment for the coexisting region can be improved. As a result, it is possible to promote the modification of the metal ions in the coexisting region to metal.

Moreover, the coexisting region formed in the present invention does not peel off even if the surface of the object to be treated is not roughened. Therefore, the smoothness of the surface to be treated can be improved, and as a result, a highly smooth metal film can be obtained. Such a metal film has a small loss due to the skin effect, and is used in high-frequency bands such as fifth-generation mobile communication systems (5G), in-vehicle millimeter-wave radar antennas, and interfaces such as MHL3.0 and Thunderbolt used for high-speed transmission. does not impair the transmission loss even when using

Moreover, the process of modifying the surface of the object to be processed with a silane coupling agent in advance is not required, and the coexisting region can be formed more easily.

In addition, as starting materials for the coexisting region formed in the present invention, a solution of a liquid phase deposition material (fluoro complex ion solution) and a metal ion solution are used instead of a colloidal solution, which is complicated to manage, so raw material management is easy. is.

In addition, the formation of the coexisting region in the present invention can control the thickness by controlling the reaction conditions such as the concentration of metal ions and the liquid phase deposition material, the temperature, and the reaction time, and the metal film obtained by the reduction treatment. generation efficiency can be controlled.

In addition, since the formation of the coexisting region in the present invention uses the liquid phase deposition material solution (fluoro complex ion solution) and the metal ion solution as starting materials, these ions can be uniformly arranged on the surface of the object to be treated. . As a result, the co-existing region can be uniformly formed on the surface of the object to be processed, so that the metal film that is modified by reduction can also be uniformly formed.

Furthermore, in the present invention, the coexisting region of the metal ion region and the liquid phase deposition material region formed on the surface to be processed is subjected to a reduction treatment using an electroless plating solution, whereby the metal ions are reduced to metal, and the metal is used as a seed. As the electroless plating progresses. Therefore, manufacturing is very simple and productivity is high.

FIG. 4 is a diagram for explaining a first film formation step of the method for forming a metal film according to Embodiment 1; FIG. 4 is a diagram for explaining a second film formation step of the method for forming a metal film according to Embodiment 1; 4A to 4C are diagrams for explaining the process of a method for forming a metal film having through holes according to the first embodiment; FIG. 1 is a diagram for explaining the configuration of a metal film forming apparatus according to Embodiment 1. FIG. FIG. 10 is a diagram for explaining the principle of a method for forming a metal film according to Embodiment 2; FIG. 10 is a diagram for explaining the process of forming a metal film according to Embodiment 2; FIG. 10 is a diagram illustrating the configuration of a metal film forming apparatus according to Embodiment 2; FIG. 10 is a diagram for explaining the principle of a method for forming a metal film according to Embodiment 3; FIG. 11 is a diagram for explaining the process of forming a metal film according to Embodiment 3; FIG. 10 is a diagram illustrating the configuration of a metal film forming apparatus according to Embodiment 3;

The method for forming a metal film according to the present invention will be described below with reference to drawings and examples. In addition, the following description illustrates one embodiment of the present invention, and the present invention is not limited to the following description. The following description can be modified without departing from the spirit of the invention. In the following description, "upper" refers to the direction away from the surface to be processed which serves as a reference, and "lower" refers to the direction to approach the surface to be processed. In addition, vertically adjacent layers or regions are said to be “directly above” or “directly below”. "Above" includes "directly above" and "below" includes "directly below."

In the method for forming a metal film of the present invention, a coexisting region of a metal ion region in which metal ions are present in a liquid phase and a liquid phase deposition material region in which a liquid phase deposition material is present is formed on the surface of an object to be processed. process and
The method is characterized by including a reduction treatment step of performing a reduction treatment on the co-existing region to reduce the metal ions and reforming the co-existing region into a metal film on the surface to be treated.

<Workpiece>
Examples of the object to be processed include an insulating substrate and an insulating substrate having a surface on which a metal layer is formed in advance. Insulating substrates include resin substrates, ceramic substrates, glass substrates, silicon substrates, and the like, and these are used as circuit substrates for various electronic devices.

As the resin substrate, those made from fluorine-based resins such as polyimide resin, methacrylic resin, epoxy resin, liquid crystal polymer, polycarbonate resin, PFA, PTFE, and ETFE can be preferably used. In addition, the resin substrate may contain glass fiber in order to improve mechanical strength.

As the ceramic substrate, those made from alumina, aluminum oxide such as sapphire, aluminum nitride, silicon nitride, silicon carbide, zirconium oxide, yttrium oxide, titanium nitride, barium titanate, and the like can be suitably used.

The glass substrate is an amorphous substrate composed of a silica network, and includes network formers (network-forming oxides) such as aluminum, boron, and phosphorus, and network modifiers (network-modifying oxides) such as alkali metals, alkaline earth metals, and magnesium. things) may be included.

A silicon substrate is a wafer made of monocrystalline silicon or polycrystalline silicon.

The metal layer preliminarily formed on the insulating substrate is mainly used as a circuit pattern, and a highly conductive metal such as aluminum, copper, or silver is formed on the insulating substrate by wet etching, dry etching, or the like. be.

<Surface to be treated>
The surface to be treated is the surface of the object to be treated, and may be a depression, a hole, or an inner wall of a through hole formed on the surface of the object to be treated as long as the liquid can reach the surface. Moreover, when a metal layer is previously formed on the surface of the insulator, the surface of the metal layer is the surface to be treated. Needless to say, the surface to be processed is a portion on which a metal film is desired to be formed.

<Metal ion region>
A metal ion region is a region having at least one or more ions selected from the group consisting of gold, palladium, platinum, silver, copper, nickel, and cobalt on the surface to be processed. The metal ion domain may be in solid or liquid phase. These metal ions can be obtained by dissolving these metals in water as inorganic acid salts or organic acid salts. As inorganic acid salts, nitrates, hydrochlorides, phosphates, sulfates, fluorides and carbonates can be suitably used. As the organic acid salt, citrate, acetate, methanesulfonate, malonate, lactate, malate and the like can be preferably used. Moreover, the metal ion region may solidify or harden together with other compounds on the surface to be treated.

The metal ion may be selected according to the metal species to be formed as the metal film. For example, when gold ions are selected, the metal seed metal is formed as the metal film. The easiness of film formation is determined by the ionization tendency, and a metal with a lower ionization tendency is easier to form a film. Specifically, gold, platinum, palladium, silver, copper, nickel, and cobalt tend to be deposited in this order.

<Liquid phase precipitation material area>
The liquid phase deposition material region is a region where the liquid phase deposition material or a solution capable of forming the liquid phase deposition material exists on the surface to be treated. A liquid-phase precipitated material is a substance that separates out of the liquid phase. Specifically, oxides deposited from fluoro complex ions can be suitably used as the liquid phase deposition material. In other words, the liquid-phase deposition material region is the oxide and the fluoro complex ion solution deposited from the fluoro complex ions on the surface to be treated. The liquid phase deposition material region is basically composed of one type of fluoro complex ion, but may be composed of a plurality of types of fluoro complex ions.

A more specific explanation will be given assuming that the liquid phase deposition material is titanium oxide. In this case, the fluoro complex ion that produces the liquid phase deposition material is hexafluorotitanate ion (TiF ₆ ²⁻ ).

A hexafluorotitanate ion is represented by TiF ₆ ²⁻ . Therefore, even if H ₂ TiF ₆ (hexafluorotitanic acid) is added to a fluoro complex ion solution in water, an aqueous solution containing hexafluorotitanate ions can be obtained.

An aqueous solution containing hexafluorotitanate ions can also be obtained by adding alkali metal salts such as Na ₂ TiF ₆ (sodium hexafluorotitanate) and K ₂ TiF ₆ (potassium hexafluorotitanate) to water. . Salts with divalent cations such as MgTiF ₆ (magnesium hexafluorotitanate) and CaTiF ₆ (calcium hexafluorotitanate) can also be used. A fluoro complex ion solution (in this case, a hexafluorotitanate ion solution) can also be obtained by using (NH ₄ ) ₂ TiF ₆ (ammonium hexafluorotitanate).

These ionic compounds break the equilibrium state with the solution to obtain a solid liquid phase deposition material. For example, when hexafluorotitanate ions (fluoro complex ions) are selected as the titanium oxide source, the hydrolysis of the formula (1) is performed on the surface of the object to be treated, either during contact with the metal ions or alone. By shifting the equilibrium of the reaction equation to the right, titanium oxide (TiO ₂ ) can be formed. This reaction is achieved by, for example, adding water or raising the liquid temperature. The concentration of the hexafluorotitanate ion after adding water should be 1 mmol/L or more, and the upper limit is the solubility of the aqueous solution containing the hexafluorotitanate ion. Also, the heating is preferably carried out between 10°C and 60°C.

Also, this hydrolysis reaction is accelerated by adding a reaction initiator. The reaction initiator is preferably a substance having a high ability to form a complex with fluorine ions. The reaction initiator can scavenge fluorine from TiF ₆ ^2- (so-called fluorine scavenger) and deposit titanium oxide (TiO ₂ ).

For example, when boric acid is added as a reaction initiator, F 4 ⁻ on the right side of formula (1) becomes BF ₄ ⁻ through the reaction of formula (2). As a result, the reaction of formula (1) proceeds to the right, and the formation of titanium oxide on the surface of the object to be treated can be accelerated. The reaction initiator is not limited to boric acid, and may be salts such as sodium borate, ammonium borate, and potassium borate.

Similarly, when an aluminum ion source is added as a reaction initiator, the reaction of formula (3) produces AlF ₆ ^3- , and the reaction of formula (1) proceeds to the right. As a result, the formation of titanium oxide on the surface of the object to be treated can be accelerated. As an aluminum ion source, in addition to metallic aluminum, inorganic acid salts such as aluminum chloride, aluminum nitrate and aluminum sulfate, and organic acid salts such as aluminum citrate, aluminum lactate and aluminum acetate can be suitably used.

Further, when a silicate ion source is added as a reaction initiator, the reaction of the formula (4) produces SiF ₆ ^2- , thereby depositing titanium oxide on the surface of the object to be treated. Silicon dioxide, sodium silicate, potassium silicate and the like can be suitably used as the silica ion source.

Hydrogen peroxide can also be suitably used as a reaction initiator, although it does not have the ability to form a complex with fluorine ions. Hydrogen peroxide has the property of perhydrolyzing hexafluorotitanate ions. As a result, a titanium peroxo complex is produced. This is a titanium oxide-containing precursor, and by bringing it into contact with the surface of the object to be treated in this state, titanium oxide precipitates on the surface of the object to be treated and promotes the formation of a liquid phase deposition material. be able to.

<Coexisting area>
The coexisting region is a region where the metal ion region and the liquid phase deposition material region coexist on the surface to be treated. The mode of coexistence is not limited, and each region may be separated into two layers and in contact with each other. The metal ion region includes the state in which metal ions are incorporated into the liquid phase deposition material (solid) deposited from the fluoro complex ion solution, the state in which metal ions are adsorbed on the surface of the liquid phase deposition material, and the state in the metal ion solution. , the liquid phase deposition region may be a solidified liquid phase deposition material or a liquid phase deposition material solution (fluoro complex ion solution).

Therefore, when the metal ion solution and the liquid phase deposition solution (fluoro complex ion solution) are mixed and integrated, when the metal ion solution and the solidified liquid phase deposition material are layered, the coexisting region is There is a case where the ions and the solidified liquid phase deposition material are both mixed and integrated as a solid. A case where the metal ion region and the liquid phase deposition material region are in a mixed state is called a "mixed coexisting region", and a case where the respective regions are separated and adjacent to each other is called a "separated coexisting region".

<Reduction treatment>
The reduction treatment is a treatment for reducing metal ions in the coexisting region and modifying them into metal elements. It can be carried out by direct action of the reducing solution on the coexisting area. When the liquid phase deposition material is a photocatalytic material, the metal ions in the coexisting region can also be reduced by irradiating the coexisting region with light such as ultraviolet rays.

As the ultraviolet irradiation, ultraviolet rays of 400 nm or less are preferable, and near-ultraviolet rays of 380 nm to 200 nm are more preferable. The illuminance should be such that the metal ions in the coexisting region are changed to metal.

As the reducing solution, solutions of formaldehyde, DMAB (dimethylamine borane), sodium hypophosphite, hydrazine, etc. can be preferably used. The reducing solution may be an electroless plating solution. The reduction treatment with ultraviolet light is called "ultraviolet reduction treatment", and the reduction treatment with a reducing solution is called "reducing agent reduction treatment".

Regardless of the method of reduction treatment, a metal film in which co-regions have been reduced has different structures depending on the type of co-region. The mixed coexisting region becomes a mixed metal film of the liquid phase deposition material and the metal. This is because when a certain area in the thickness direction of the metal film is observed by SEM, TEM, or the like on the cross section of the metal film, the liquid phase deposition material also exists in the range where the metal exists, and in the thickness direction of the metal film It is a metal film in which both the metal and the liquid phase deposition material are present.

On the other hand, in the separation-coexistence region, in the direction of the metal film thickness (direction from the surface of the metal film toward the surface to be treated), the metal layer is almost rich in metal and the liquid phase deposition material layer is rich in liquid phase deposition material. split up. This is called an isolated metal film. Both a mixed metal film and an isolated metal film are metal films 20 according to the present invention.

In the method of forming the metal film according to the present invention, several methods are conceivable depending on the method of forming the coexisting region and the method of reduction treatment. Representative methods will be sequentially described below. It should be noted that the above-mentioned "object to be treated", "surface to be treated", "metal ion region", "liquid phase deposition material region" and "coexisting region" can be appropriately applied in common to the following embodiments. can.

(Embodiment 1): Mixed Coexisting Region + Reducing Agent Reduction Treatment FIGS. 1 and 2 show a method for forming a metal film in Embodiment 1. FIG. 1 and 2, the fluoro-complex ion was designated as "F ion", the metal as "M", and the metal ion as "M ⁺ ".

In the first embodiment, the treatment surface 12 of the treatment object 10 is coated with fluoro complex ions such as hexafluorotitanate ions (TiF ₆ ²⁻ ) and hexafluorosilicate ions (SiF ₆ ²⁻ ), metal ions ( A first film formation step ( ^coexisting forming a region);
A second film formation step (reduction ^treatment : reduction agent reduction treatment).

Here, hexafluorotitanate ions (TiF ₆ ²⁻ ) and hexafluorosilicate ions (SiF ₆ ²⁻ ) are fluoro complex ions that precipitate the liquid phase deposition material, and these solutions are in the liquid phase deposition material region. becomes. Also, the metal ion region is a solution of metal ions. Co-existing regions are these reaction solutions 60 . The liquid phase deposition material region and the metal ion region are in a mixed state in the coexistence region, and the coexistence region in the first embodiment is a mixed coexistence region. In addition, the mixed layer 14 in which the liquid phase deposition material takes in the metal ions and solidifies is also a coexisting region (mixed coexisting region).

The concentration of fluoro complex ions is preferably 0.1 M or more, and the concentration of metal ions is preferably 1 mM or more. If the amount of fluoro complex ions is small, the efficiency of forming the metal film 20 is low, and the adhesion strength to the surface 12 to be treated is also low. On the other hand, if the amount of metal ions is small, the conductivity of the metal film 20 will be low.

The formation principle of the mixed layer 14 will be described with reference to FIG. Fluoro complex ions are hexafluorotitanate ions (TiF ₆ ²⁻ ), hexafluorosilicate ions (SiF ₆ ²⁻ ), etc., but are not limited to these.

In the first film forming step, the surface 12 of the object 10 to be processed is exposed to a reaction solution 60 containing fluorocomplex ions (F ions) and metal ions (M ⁺ ) (FIG. 1(a)). A reaction initiator may be added to this reaction solution 60 as already explained.

Fluoro complex ions (F ions) are deposited on the surface 12 to be processed as a liquid-phase deposition material (titanium oxide (TiO ₂ ), silicon dioxide (SiO ₂ ), or the like). During this deposition, the metal ions (M ⁺ ) are taken in while being deposited. As a result, a mixed layer 14 (coexisting region) composed of the liquid phase deposition material and metal ions (M ⁺ ) is formed on the surface 12 to be treated (FIG. 1(b)).

The reaction time for forming the mixed layer 14 (coexisting region) is determined from the required film thickness of the mixed layer 14 . There is a linear relationship between the reaction time and the film thickness of the mixed layer 14, and by adjusting the reaction time, the mixed layer 14 with a film thickness of several nanometers to several tens of micrometers can be obtained.

During the reaction, the liquid phase deposition material may be generated as particles in the reaction solution 60 in addition to being deposited on the surface 12 of the object 10 to be processed. In that case, in order to remove particles in the reaction solution 60, a step of withdrawing a part of the reaction solution 60, filtering it with a filter, and returning it may be performed. Such a process can be called a filtering process.

After the mixed layer 14 is formed, the reaction solution 60 is removed (FIG. 1(c)). The mixed layer 14 formed on the surface 12 to be treated is a coexisting region. After that, heat treatment or the like may be performed. This heat treatment improves the adhesion between the mixed layer 14 and the surface 12 to be treated. This heat treatment can be called a heating step.

Next, the second film forming process will be described. Referring to FIG. 2, object 10 having mixed layer 14 formed on surface 12 to be treated is immersed in reducing solution 16 (FIG. 2(a)). Metal ions (M ⁺ ) in the mixed layer 14 are reduced to metal (M) by the reducing power of the reducing solution 16, and the mixed layer 14 is reformed into the metal film 20 in which the liquid phase deposition material and the metal coexist. (Fig. 2(b)). This treatment is a reduction treatment, and since it is directly reduced by a reducing agent, it is a reducing agent reduction treatment. The mixed metal film 19 is the metal film 20 obtained by modifying the mixed layer 14 .

The reducing solution 16 can also be an electroless plating solution. Electroless plating solutions are composed of reducing agents such as formaldehyde, DMAB (dimethylamine borane), sodium hypophosphite, hydrazine, etc., and plating metal ions. The mixed layer 14 is modified into the metal film 20 by the electroless plating solution, and at the same time as the modification to the metal film 20, electroless plating is performed using the metal film 20 (mixed metal film 19) as a seed. (Fig. 2(c)).

As a result, an electroless plated layer 22 is formed on the metal film 20 . Note that the electroless plated layer 22 may also be called a metal film 20 . This is because if the plating metal and the metal (M) forming the mixed layer 14 are of the same kind, they cannot be distinguished from each other. Regardless of the presence or absence of the electroless plating layer 22, the mixed metal film 19 (metal film 20) contains the liquid phase deposition material.

In the above method, it can be said that the mixed layer 14 is formed using the LPD method. By using the LPD method to form the mixed layer 14, the hydroxyl groups on the surface 12 of the object 10 to be processed and the liquid phase precipitation material in the mixed layer 14 are combined with chemical bonding to form the mixed layer 14. Therefore, a very strong layer can be formed. By modifying the mixed layer 14 by reduction treatment, the metal film 20 (mixed metal film 19) firmly bonded to the surface 12 to be treated can be obtained.

After forming the metal film 20, the film may be further increased by plating. The plating at this time may be electroless plating as described above, or electrolytic plating. Either method can be used because the metal film 20 is already formed. This plating is called a film-increasing process.

A product manufactured by using the method for forming the metal film 20 according to the first embodiment is called an electronic product 1 . The electronic product 1 includes not only electronic-related products such as circuit boards, semiconductor circuits, and electronic components, but also products using the metal film 20 according to the first embodiment as a protective film and a decorative finishing film.

FIG. 3 schematically shows the process of forming a metal film with a through hole 10h using an insulating substrate as the object 10 to be processed. FIGS. 3(a) to 3(c) show the case where the object 10 to be processed is only the insulating substrate 10a, and FIGS. This is the case with the pre-formed metal layer 10b. Each shows a cross section including a through hole 10h.

Please refer to FIGS. 3(a) and 3(d). As a pretreatment for the first film forming step for forming the mixed layer 14 , it is preferable to subject these objects 10 to be treated to an operation for exposing hydroxyl groups to the surface 12 to be treated. For example, it is preferable to carry out acid treatment, alkali treatment, ultraviolet irradiation treatment, electron beam (ion beam) irradiation treatment, plasma treatment, coupling agent treatment, and the like.

As already described, the surface 12 to be processed includes not only the surface of the object 10 to be processed, but also the inner walls 10hi of the through holes 10h when the object 10 to be processed has the through holes 10h. In Embodiment 1, since the coexisting region (here, the mixed layer 14) is formed in the liquid phase, the mixed layer 14 can also be formed on the inner wall 10hi of the through hole 10h.

The portion where the metal film 20 is not formed is the surface of the object to be processed 10 but not the surface to be processed 12 . In FIG. 3, the back surface 10r (lower side in the drawing) of the object 10 to be processed is not the surface 12 to be processed. Such a surface can be prevented from forming the mixed layer 14 by masking it in advance.

When the object 10 to be processed has the metal layer 10b formed on the surface of the insulating substrate 10a (FIG. 3(d)), the surface to be processed 12 is the surface of the metal layer 10b. Further, when a through-hole 10h is formed in the insulating substrate 10a having the metal layer 10b formed on the surface thereof, the inner wall 10hi of the through-hole 10h also serves as the surface 12 to be processed. In this case, the inner wall 10hi of the through-hole 10h includes a cross-sectional portion 12b of the surface metal layer 10b and a cross-sectional portion 12a of the insulating substrate 10a that follows.

As described above, in the method of forming the metal film 20 according to the first embodiment, since the coexisting region on the surface 12 to be processed is formed in the liquid phase, even the surface perpendicular to the surface such as the inner wall 10hi of the through-hole 10h. A metal film 20 can be formed as the surface 12 to be processed.

3(b) and 3(e) show the state in which the mixed layer 14 is formed. Since the mixed layer 14 is formed in a liquid phase, the mixed layer 14 is also formed on the inner wall 10hi of the through hole 10h. In FIGS. 3(b) and 3(e), the mixed layer 14 formed on the inner wall 10hi of the through hole 10h is indicated by reference numeral "14i". Since the mixed layer 14 is formed in a liquid phase, a dense continuous film is formed. Here, the continuous film means a state in which no gap is formed with the surface to be processed 12 and there is no unformed portion (so-called “film void”) over the entire surface to be processed 12 .

Further, in the mixed layer 14, the fluoro complex ions are modified into a solidified liquid phase deposition material, and the metal exists in the state of metal ions. When the mixed layer 14 is formed from the reaction solution 60, there is usually no selectivity between the fluoro complex ions and the metal ions. It is formed.

3(c) and 3(f), after the mixed layer 14 is formed, a reducing solution 16 is brought into contact with the mixed layer 14 on the surface 12 to be processed, whereby the metal film 20 is formed. (second film formation step). In FIGS. 3(c) and 3(f), the metal film 20 in the through hole 10h is indicated by the symbol "20i".

After forming the metal film 20, the object 10 to be processed can be washed to obtain the electronic product 1 according to the first embodiment.

As described above, the procedure for forming the metal film 20 in FIG. 3 is as shown in FIGS. That is, by immersing the object 10 to be treated in the reaction solution 60, a mixed layer 14, which is a coexisting region in which a metal ion region and a liquid phase deposition material region coexist, is formed on the surface 12 to be treated (Fig. 3(b) ) and FIG. 3(e)). After that, the metal ions in the mixed layer 14 are reduced by being immersed in a reducing solution 16 to obtain a metal film 20 (mixed metal film 19) (FIGS. 3(c) and 3(f)). Since the mixed layer 14 is also formed within the inner wall 10hi of the through hole 10h, the metal film 20 can be formed also on the inner wall 10hi surface of the through hole 10h.

<Manufacturing equipment>
Next, referring to FIG. 4, the forming apparatus 50 for forming the metal film 20 according to the first embodiment will be described. A forming apparatus 50 for forming the metal film 20 according to the first embodiment is composed of a first film forming unit 52 and a second film forming unit 54 . Also, a heating unit 56 may be attached. Moreover, although not shown, a plating apparatus for plating the completed electronic product 1 may be attached.

The first film-forming part 52 is a part for forming the mixed layer 14 composed of metal ions and a liquid-phase deposition material on the surface 12 of the object 10 to be processed in a liquid phase. Here, a type of immersing the object 10 to be processed in a reaction solution 60 containing fluoro complex ions and metal ions will be described. Alternatively, the reaction solution 60 can be brought into contact with the surface 12 to be treated by showering.

The first film forming section 52 has a first bath 52a that stores a reaction solution 60 containing fluoro complex ions and metal ions. The first bathtub 52a may be provided with a circulation pipe 52d via a filter 52b and a pump 52c arranged in the circulation pipe 52d. Also, a heater 52j may be provided in the first bathtub 52a.

Further, a reaction initiator tank 52e storing a reaction initiator, a pipe 52f for guiding the reaction initiator to the first bath 52a, and a valve 52g for controlling introduction of the reaction initiator into the first bath 52a may be provided. .

The second film forming section 54 causes the reducing solution 16 to act on the workpiece 10 provided with the mixed layer 14 . Here, the reducing solution 16 is caused to act on the processing object 10 by immersing the processing object 10 in the second bath 54 a in which the reducing solution 16 is stored. In the apparatus 50 for forming the metal film 20, the heating unit 56 has a heating furnace 56a.

Next, the operation of the apparatus 50 for forming the metal film 20 will be described along with the process flow of the object 10 to be processed. The object 10 to be processed is an insulating substrate having a through hole 10h. Here, it is assumed that two through holes 10h are formed. A mask 64 is attached to this. The mask 64 is a mask for exposing only the processed surface 12 of the processed object 10 . Here, it is assumed that the surface 12 to be processed is the inner wall and periphery of the through holes 10h and the connecting line connecting the through holes 10h. Although FIG. 4 shows the mask 64 only for the front side of the object 10 to be processed, the rear surface 10r (see FIG. 3) may be masked.

The object to be processed 10 with the mask 64 is immersed in the first bath 52a in which the reaction solution 60 containing fluoro complex ions and metal ions is stored. After that, the reaction initiator is introduced from the reaction initiator tank 52e into the first bath 52a through the pipe 52f. Thus, precipitation starts from fluoro complex ions, and a mixed layer 14 composed of metal ions and a liquid-phase deposition material is formed on the surface 12 to be treated. By warming the first bath 52a with a heater 52j and raising the temperature of the reaction solution 60 containing fluoro complex ions and metal ions, the mixed layer 14 can be formed without using a reaction initiator. can be done.

Further, when fine particles of the liquid phase deposition material precipitate and float in the reaction solution 60 containing fluoro complex ions and metal ions in the first bath 52a, the pump 52c is operated, and the circulation pipe 52d through the filter 52b The reaction solution 60 is filtered and circulated. This circulation removes fine particles of the liquid phase deposition material.

The object 10 on which the mixed layer 14 has been formed is pulled up from the first bath 52a, the mask 64 is removed, and the object 10 is put into the heating furnace 56a and heated. Note that the heating in the heating furnace 56a may not be performed. Further, when the heating furnace 56a is used, the temperature of the workpiece 10 becomes high, so the mask 64 may be made of a material that evaporates with the heat of the heating furnace 56a. This is because the trouble of removing the mask 64 is eliminated.

The workpiece 10 on which the mixed layer 14 is formed is immersed in the second bath 54a in which the reducing solution 16 of the second film forming section 54 is stored. By this operation, the reducing solution 16 in the second bath 54a acts on the object 10 to be processed, the mixed layer 14 is modified, and the metal film 20 (mixed metal film 19) is obtained. Further, when the reducing solution 16 is an electroless plating solution, the metal film 20 (electroless plating layer 22) is formed subsequent to the metal film 20 (mixed metal film 19). As described above, the electronic product 1 having the metal film 20 formed on the processed surface 12 of the processed object 10 is obtained. After this, a film-increasing step may be performed.

(Embodiment 2) Mixed Coexisting Region + Ultraviolet Reduction Treatment FIG. 5 shows a method of forming the metal film 20 in Embodiment 2. FIG. In Embodiment 2, a liquid-phase deposition material such as hexafluorotitanate ions (TiF ₆ ²⁻ ) is applied to the surface 12 of the object 10 to be treated as a photocatalytic fluoro complex ion (which is referred to as a photocatalytic fluoro-complex ion). complex ions”) and a reaction solution 60 containing metal ions (M ⁺ ) are brought into contact with each other to form a solidified mixed layer 15 containing a liquid phase deposition material (photocatalyst material) and metal ions. A metal film 20 is obtained by a film step (step of forming a coexisting region) and irradiating the mixed layer 15 with ultraviolet rays 17 to reduce metal ions (M ⁺ ) in the mixed layer 15 to metal (M). It is characterized by having a third film forming step (reduction treatment: ultraviolet reduction treatment). In addition, in Embodiment 2, you may call a 3rd film-forming process a 2nd film-forming process.

Here, for example, hexafluorotitanate ions (TiF ₆ ²⁻ ) are fluoro complex ions of a photocatalyst material that deposits a liquid phase deposition material, and a solution or liquid phase deposition material of these ions forms a liquid phase deposition material region. Titanium, zinc, zirconium, tin and the like can be suitably used as metal species for the liquid phase deposition material to be a photocatalyst material.

Also, the metal ion region is a portion where metal ions taken into the metal ion solution or the liquid phase deposition material exist. The coexisting area is these reaction solutions 61 . The liquid phase deposition material region and the metal ion region are in a mixed state in the coexistence region, and the coexistence region in the second embodiment is a mixed coexistence region. In addition, the mixed layer 15 in which the liquid phase deposition material takes in the metal ions and solidifies is also a mixed coexisting region.

The concentration of fluoro complex ions is preferably 0.1 M or more, and the concentration of metal ions is preferably 1 mM or more. If the amount of fluoro complex ions is small, the efficiency of forming the metal film 20 is low, and the adhesion strength to the surface 12 to be treated is also low. On the other hand, if the amount of metal ions is small, the conductivity of the metal film 20 will be low.

First, the formation principle of the mixed layer 15 will be described with reference to FIG. The first film forming process for forming the mixed layer 15 is the same as the first film forming process described in the first embodiment. That is, the reaction solution 61 containing the fluoro complex ions of the photocatalytic material and the metal ions is brought into contact with the surface 12 to be treated (FIG. 5A), and the mixed layer 15 composed of the liquid phase deposition material and the metal ions is deposited (FIG. 5 (b)). A reaction initiator may be added to the reaction solution 61 in order to precipitate the liquid phase deposition material.

After removing the reaction solution 61 (FIG. 5(c)), the ultraviolet rays 17 are irradiated. Irradiation of the ultraviolet rays 17 is a reduction treatment, which is the third film forming process. In the mixed layer 15, the liquid phase deposition material, which is a photocatalyst material, emits electrons due to the irradiation of the ultraviolet rays 17, thereby reducing the metal ions (M ⁺ ) to metal (M). As a result, the mixed layer 15 is modified into a metal film 20 (mixed metal film 19) in which the liquid phase deposition material and the metal coexist (FIG. 5(d)). As in the first embodiment, the mixed metal film 19 contains a liquid phase deposition material.

After forming the metal film 20, the film may be further increased by plating. The plating at this time may be electroless plating as described above, or electrolytic plating. Either method can be used because the metal film 20 is already formed. This plating is called a film-increasing process.

A product manufactured by using the method for forming the metal film 20 according to the second embodiment is called an electronic product 1 . The electronic product 1 includes not only electronic-related products such as circuit boards, semiconductor circuits, and electronic components, but also products using the metal film 20 according to the second embodiment as a protective film and a decorative finishing film.

FIG. 6 schematically shows the process of forming a metal film according to the second embodiment, with the workpiece 10 being an insulating substrate having through holes 10h. 6(a) to 6(c) show the case where the object 10 to be processed is only the insulating substrate 10a, and FIGS. This is the case with the pre-formed metal layer 10b. Each shows a cross section including a through hole 10h.

Please refer to FIGS. 6(a) and 6(d). As a pretreatment for the first film forming step for forming the mixed layer 15 , it is preferable to subject these objects 10 to be treated to an operation for exposing hydroxyl groups to the surface 12 to be treated. For example, it is preferable to carry out acid treatment, alkali treatment, ultraviolet irradiation treatment, electron beam (ion beam) irradiation treatment, plasma treatment, coupling agent treatment, and the like.

As already described, the surface 12 to be processed includes not only the surface of the object 10 to be processed, but also the inner walls 10hi of the through holes 10h when the object 10 to be processed has the through holes 10h. In Embodiment 2, since the coexisting region (here, the mixed layer 15) is formed in the liquid phase, the mixed layer 15 can also be formed on the inner wall 10hi of the through hole 10h.

The portion where the metal film 20 is not formed is the surface of the object to be processed 10 but not the surface to be processed 12 . In FIG. 6, the back surface 10r (lower side in the drawing) of the object 10 to be processed is not the surface 12 to be processed. Such a surface can be prevented from forming the mixed layer 15 by masking it in advance.

When the object to be processed 10 has the metal layer 10b formed on the surface of the insulating substrate 10a (FIG. 6D), the surface to be processed 12 is the surface of the metal layer 10b. Further, when a through-hole 10h is formed in the insulating substrate 10a having the metal layer 10b formed on the surface thereof, the inner wall 10hi of the through-hole 10h also serves as the surface 12 to be processed. In this case, the inner wall 10hi of the through-hole 10h includes a cross-sectional portion 12b of the surface metal layer 10b and a cross-sectional portion 12a of the insulating substrate 10a that follows.

6(b) and 6(e) show the state in which the mixed layer 15 is formed. Since the mixed layer 15 is formed in a liquid phase, the mixed layer 15 is also formed on the inner wall 10hi of the through hole 10h. In FIGS. 6(b) and 6(e), the mixed layer 15 formed on the inner wall 10hi of the through-hole 10h is denoted by reference numeral "15i". Since the mixed layer 14 is formed in a liquid phase, a dense continuous film is formed. Here, the continuous film means a state in which no gap is formed with the surface to be processed 12 and there is no unformed portion (so-called “film void”) over the entire surface to be processed 12 .

Further, in the mixed layer 14, the fluoro complex ions are modified into a solidified liquid phase deposition material, and the metal exists in the state of metal ions. When the mixed layer 15 is formed from the reaction solution 61, there is usually no selectivity between the fluoro complex ions and the metal ions. It is formed.

6(c) and 6(f), after the mixed layer 15 is formed, the surface 12 of the object 10 to be processed and the through hole 10h are irradiated with ultraviolet rays 17, whereby the metal film 20 ( A mixed metal film 19) is formed (third film forming step). In FIGS. 6(c) and 6(f), the metal film 20 in the through hole 10h is indicated by the symbol "20i".

A laser, a light-emitting diode, an ultraviolet light lamp, or the like can be suitably used as a light source for ultraviolet irradiation, and a combination thereof may also be used. In particular, when the through-holes 10h are formed in the object 10 to be processed, a light source capable of generating a light flux with high straightness, such as a laser, is preferable.

The wavelength of the ultraviolet rays to be irradiated is 400 nm or less, preferably near ultraviolet rays of 380 nm to 200 nm. The illuminance should be such that the mixed layer 15 is modified into the metal film 20 .

After forming the metal film 20, the object 10 to be processed can be washed to obtain the electronic product 1 according to the second embodiment.

The procedure for forming the metal film 20 is as shown in FIG. That is, by immersing the object 10 to be treated in the reaction solution 61, a mixed layer 15, which is a coexisting region in which a metal ion region and a liquid phase deposition material region coexist, is formed on the treated surface 12 (FIG. 6B ) and (e)). Thereafter, the metal ions in the mixed layer 15 are reduced by irradiation with ultraviolet rays 17 to obtain a metal film 20 (FIGS. 6(c) and (f)). Since the mixed layer 15 is also formed within the inner wall 10hi of the through hole 10h, the metal film 20 can be formed also on the inner wall 10hi surface of the through hole 10h.

<Manufacturing equipment>
Next, with reference to FIG. 7, an apparatus 70 for forming the metal film 20 according to the second embodiment will be described. A forming apparatus 70 for forming the metal film 20 according to the second embodiment includes a first film forming unit 52 and a third film forming unit 74 (the second film forming unit 72 only in the second embodiment). Also, a heating unit 56 may be attached. Moreover, although not shown, a plating apparatus for plating the completed electronic product 1 may be attached.

The first film forming part 52 is a part that forms the mixed layer 15 on the surface 12 of the object 10 to be processed in a liquid phase. It is the same as the case of the first embodiment. Here, a type of immersing the object 10 to be processed in a reaction solution 61 containing fluoro complex ions of a photocatalytic material and metal ions will be described. As another method, the reaction solution 61 can be brought into contact with the surface 12 to be treated by a shower method.

The first film forming section 52 has a first bath 52a that stores a reaction solution 61 containing fluoro complex ions of photocatalyst materials and metal ions. The first bathtub 52a may be provided with a circulation pipe 52d via a filter 52b and a pump 52c arranged in the circulation pipe 52d. Also, a heater 52j may be provided in the first bathtub 52a.

Further, a reaction initiator tank 52e storing a reaction initiator, a pipe 52f for guiding the reaction initiator to the first bath 52a, and a valve 52g for controlling introduction of the reaction initiator into the first bath 52a may be provided. .

The third film forming unit 74 applies ultraviolet rays 17 to the object 10 on which the mixed layer 15 is provided. Therefore, the third film forming section 74 has an irradiation table 74a and an ultraviolet light source 74b. In the apparatus 70 for forming the metal film 20, the heating section 56 has a heating furnace 56a.

Next, the operation of the apparatus 70 for forming the metal film 20 will be described along with the process flow of the object 10 to be processed. The object 10 to be processed is an insulating substrate having a through hole 10h. Here, it is assumed that two through holes 10h are formed. A mask 64 is attached to this. The mask 64 is a mask for exposing only the processed surface 12 of the processed object 10 . Here, it is assumed that the surface to be processed 12 is the inner wall and periphery of the through holes 10h and the connecting line connecting the through holes 10h. Although FIG. 7 shows the mask 64 only for the front side of the object 10 to be processed, the rear surface 10r (see FIG. 6) may be masked.

The object to be processed 10 with the mask 64 applied thereto is immersed in the first bath 52a in which the reaction solution 61 containing the fluoro complex ions of the photocatalytic material and the metal ions is stored. After that, the reaction initiator is introduced from the reaction initiator tank 52e into the first bath 52a through the pipe 52f. Thus, a mixed layer 15 is formed on the surface 12 to be processed. By warming the first bath 52a with the heater 52j and raising the temperature of the reaction solution 61 containing the fluoro complex ions of the photocatalytic material and the metal ions, the mixed layer 15 can be formed without using the reaction initiator. can be formed.

Further, when the fine particles of the liquid phase deposition material precipitate and float in the reaction solution 61 containing the fluoro complex ions of the photocatalyst material and the metal ions in the first bath 52a, the pump 52c is operated and the circulation pipe through the filter 52b At 52d, the reaction solution 61 is filtered and circulated. This circulation removes fine particles of the liquid phase deposition material.

The object 10 on which the mixed layer 15 has been formed is pulled up from the first bath 52a, the mask 64 is removed, and the object 10 is put into the heating furnace 56a and heated. Note that the heating in the heating furnace 56a may not be performed. Further, when the heating furnace 56a is used, the temperature of the workpiece 10 becomes high, so the mask 64 may be made of a material that evaporates with the heat of the heating furnace 56a. This is because the trouble of removing the mask 64 is eliminated.

The workpiece 10 on which the mixed layer 15 is formed is placed on the irradiation table 74a of the third film forming section 74, and is irradiated with the ultraviolet rays 17 from the ultraviolet light source 74b.

The ultraviolet rays 17 supply electrons from the liquid-phase deposition material, which is a photocatalyst material in the mixed layer 15, and reduce the metal ions to metal. As a result, the mixed layer 15 is modified into the metal film 20 . A film-increasing step may be added after the metal film 20 is formed.

As described above, the electronic product 1 having the metal film 20 formed on the processed surface 12 of the processed object 10 is obtained. The electronic product 1 includes not only electronic-related products such as circuit boards, semiconductor circuits, and electronic components, but also products using the metal film 20 according to the first embodiment as a protective film and a decorative finishing film.

(Embodiment 3): Separation coexisting region + ultraviolet reduction treatment Figs. In the third embodiment, an aqueous solution containing fluoro complex ions of a photocatalytic material is brought into contact with the surface 12 of the object 10 to be processed, and a layer of liquid phase deposition material is formed on the surface 12 to be processed (referred to as a liquid phase deposition material layer 13). a liquid phase deposition material region), and a fifth step of forming a coexisting region by bringing a metal ion solution 18 (metal ion region) into contact with the liquid phase deposition material layer 13. and a sixth film forming step of irradiating the coexisting region with ultraviolet rays 17 to form the metal ion solution 18 (metal ion region) directly above the liquid phase deposition material layer 13 into the metal film 20. Characterized by

In Embodiment 3, first, a liquid phase deposition material layer 13 formed of a photocatalytic liquid phase deposition material is formed on the surface 12 to be processed (FIG. 8A: fourth film forming step). Next, a metal ion solution 18 (metal ion region) is brought into contact with the liquid phase deposition material layer 13 to form a coexisting region (fifth film formation step). That is, here, the coexisting region is a combination of the solid-phase liquid-phase deposition material layer 13 and the liquid-phase metal ion solution 18 .

Next, the coexisting area is irradiated with ultraviolet rays 17 . Since the liquid phase deposition material layer 13 is a photocatalyst material, it emits electrons 13 e by the ultraviolet rays 17 . The metal ions 18a are reduced by the electrons 13e (FIG. 8(b)), and a metal layer 20b is formed immediately above the liquid phase deposition material layer 13 (FIG. 8(c)). In Embodiment 3, the liquid phase deposition material layer 13 and the metal layer 20b constitute the metal film 20 (separation type metal film 21). The irradiation of the ultraviolet rays 17 is an ultraviolet reduction treatment in the reduction treatment. The irradiation of the ultraviolet rays 17 is the sixth film forming process.

In the present embodiment 3, the fourth film forming process, the fifth film forming process and the sixth film forming process are respectively the first film forming process, the second film forming process and the third film forming process. You may call it a film-forming process.

A product manufactured using the method for forming the metal film 20 (separate metal film 21) according to the third embodiment is called an electronic product 1. FIG. The electronic product 1 includes not only electronic-related products such as circuit boards, semiconductor circuits, and electronic components, but also products using the metal film 20 according to the third embodiment as a protective film and a decorative finishing film.

FIG. 9 schematically shows the process of forming a metal film according to the third embodiment, with the workpiece 10 being an insulating substrate 10a. 9(a) to 9(c) show the case where the object 10 to be processed is only the insulating substrate 10a, and FIGS. This is the case with the pre-formed metal layer 10b. Each shows a cross section including a through hole 10h.

Please refer to FIGS. 9(a) and 9(d). As a pretreatment for the fourth film forming step for forming the liquid phase precipitation material layer 13 , the object 10 to be treated is preferably subjected to an operation for exposing hydroxyl groups to the surface 12 to be treated. For example, it is preferable to carry out acid treatment, alkali treatment, ultraviolet irradiation treatment, electron beam (ion beam) irradiation treatment, plasma treatment, coupling agent treatment, and the like.

As already described, the surface 12 to be processed includes not only the surface of the object 10 to be processed, but also the inner walls 10hi of the through holes 10h when the object 10 to be processed has the through holes 10h. In Embodiment 3, since the coexisting region (here, the liquid phase deposition material layer 13 and the metal ion solution 18) is formed in the liquid phase, the metal film 20 can also be formed on the inner wall 10hi of the through hole 10h.

The portion where the metal film 20 is not formed is the surface of the object to be processed 10 but not the surface to be processed 12 . In FIG. 1, the back surface 10r (see FIG. 9) of the object 10 to be processed is not the surface 12 to be processed. By masking such a surface in advance, the liquid phase deposition material layer 13 can be prevented from being formed.

When the object to be processed 10 has the metal layer 10b formed on the surface of the insulating substrate 10a (FIG. 9(d)), the surface to be processed 12 is the surface of the metal layer 10b. Further, when a through-hole 10h is formed in the insulating substrate 10a having the metal layer 10b formed on the surface thereof, the inner wall 10hi of the through-hole 10h also serves as the surface 12 to be processed. In this case, the inner wall 10hi of the through-hole 10h includes a cross-sectional portion 12b of the surface metal layer 10b and a cross-sectional portion 12a of the insulating substrate 10a that follows.

As described above, in the method of forming the metal film 20 according to the third embodiment, since the coexisting region on the surface 12 to be processed is formed in the liquid phase, even the surface perpendicular to the surface such as the inner wall 10hi of the through-hole 10h. A metal film 20 can be formed as the surface 12 to be processed.

9(b) and 9(e) show the state in which the liquid phase deposition material layer 13 is formed (fourth film formation step). Since the liquid phase deposition material layer 13 is formed in the liquid phase, the liquid phase deposition material layer 13 is also formed on the inner wall 10hi of the through hole 10h. In FIGS. 9B and 9E, the liquid phase deposition material layer 13 formed on the inner wall 10hi of the through hole 10h is indicated by reference numeral "13i". Since the liquid phase deposition material layer 13 is formed in a liquid phase, a dense continuous film is formed. Here, the continuous film means a state in which no gap is formed with the surface to be processed 12 and there is no unformed portion (so-called “film void”) over the entire surface to be processed 12 .

9(c) and 9(f), after liquid phase deposition material layer 13 is formed, metal ion solution 18 is brought into contact with liquid phase deposition material layer 13 (fifth film forming step). ). In Embodiment 3, the coexisting region is composed of the solidified liquid phase deposition material layer 13 and the liquid metal ion solution 18 .

Then, the coexisting region is irradiated with ultraviolet rays 17 (sixth film forming step). Since the liquid phase deposition material layer 13 is formed of a photocatalytic material, it emits electrons 13e when irradiated with ultraviolet rays 17, reduces metal ions 18a in the metal ion solution 18, and reforms them into metal. As a result, the metal layer 20b is formed right above the liquid phase deposition material layer 13. Next, as shown in FIG. The metal film 20 is composed of the liquid phase deposition material layer 13 and the metal layer 20b. In FIGS. 9(c) and 9(f), the metal layer 20b in the through hole 10h is indicated by the symbol "20bi".

After forming the metal film 20, the film may be further increased by plating. The plating at this time may be electroless plating as described above, or electrolytic plating. Either method can be used because the metal film 20 is already formed. This plating is called a film-increasing process.

After forming the metal film 20, the object 10 to be processed can be washed to obtain the electronic product 1 according to the third embodiment. The electronic product 1 includes not only electronic-related products such as circuit boards, semiconductor circuits, and electronic components, but also products using the metal film 20 according to the first embodiment as a protective film and a decorative finishing film.

As described above, the procedure for forming the metal film 20 in FIG. 9 is as shown in FIG. That is, the object 10 to be treated is immersed in a fluoro complex ion solution of a photocatalyst material to form a layer 13 of liquid phase deposition material on the surface 12 to be treated (FIGS. 9B and 9E). After that, the metal ion solution 18 is brought into contact with the liquid phase deposition material layer 13 of the photocatalyst material to form a coexisting region. By irradiating the ultraviolet rays 17, the metal ions in the metal ion solution 18 are reduced, and the metal layer 20b can be obtained directly above the liquid phase deposition material layer 13 (FIGS. 9C and 9F). )). The liquid phase deposition material layer 13 is also formed in the inner wall 10hi of the through hole 10h, and the metal ion solution 18 can be sent onto the liquid phase deposition material layer 13 without fail, so that the metal layer 20b is also formed on the inner wall 10hi surface of the through hole 10h. can be formed.

<Manufacturing equipment>
Next, with reference to FIG. 10, an apparatus 80 for forming the metal film 20 (separate metal film 21) according to the third embodiment will be described. A forming apparatus 80 for forming the metal film 20 according to the third embodiment is composed of a fourth film forming section 82 , a fifth film forming section 84 and a sixth film forming section 85 . Also, a heating unit 56 may be attached. Moreover, although not shown, a plating apparatus for further plating the completed electronic product 1 may be attached. In addition, within the third embodiment, the fourth film forming unit 82, the fifth film forming unit 84, and the sixth film forming unit 85 are the first film forming unit 82, the second film forming unit 84, and the third film forming unit. It may be the film portion 85 .

The fourth film forming part 82 is a part where the liquid phase deposition material layer 13 is formed in the liquid phase on the surface 12 to be processed of the object 10 to be processed. Here, a type in which the object 10 to be processed is immersed in the fluoro complex ion solution 62 will be described. As another method, the fluoro complex ion solution 62 can be brought into contact with the surface 12 to be treated by a shower method.

The fourth film-forming section 82 has a first bath 52a in which the fluoro complex ion solution 62 is stored. The first bathtub 52a may be provided with a circulation pipe 52d via a filter 52b and a pump 52c arranged in the circulation pipe 52d. Also, a heater 52j may be provided in the first bathtub 52a.

Further, a reaction initiator tank 52e storing a reaction initiator, a pipe 52f for guiding the reaction initiator to the first bath 52a, and a valve 52g for controlling introduction of the reaction initiator into the first bath 52a may be provided. .

The fifth film forming section 84 forms a coexisting region by immersing the object 10 provided with the liquid phase deposition material layer 13 in the metal ion solution 18 . Therefore, the fifth film forming section 84 has a second bath 54 a that stores the metal ion solution 18 .

The sixth film forming unit 85 irradiates the object 10 to be processed while being immersed in the metal ion solution 18 with the ultraviolet rays 17 to form the metal layer 20b on the liquid phase deposition material layer 13 formed on the surface 12 to be processed. do. Therefore, the sixth film forming section 85 has an ultraviolet light source 85a. In the apparatus 80 for forming the metal film 20, the heating section 56 has a heating furnace 56a.

Next, the operation of the apparatus 80 for forming the metal film 20 will be described along with the process flow of the object 10 to be processed. The object 10 to be processed is an insulating substrate having a through hole 10h. Here, it is assumed that two through holes 10h are formed. A mask 64 is attached to this. The mask 64 is a mask for exposing only the processed surface 12 of the processed object 10 . Here, it is assumed that the surface 12 to be processed is the inner wall and periphery of the through holes 10h and the connecting line connecting the through holes 10h. FIG. 10 shows the mask 64 only for the front side of the object 10 to be processed, but the back surface 10r (see FIG. 9) may be masked.

The object to be processed 10 with the mask 64 is immersed in the first bath 52a in which the fluoro complex ion solution 62 is stored. After that, the reaction initiator is introduced from the reaction initiator tank 52e into the first bath 52a through the pipe 52f. Thus, the liquid phase deposition material layer 13 is formed on the surface 12 to be processed. By warming the first bath 52a with the heater 52j and raising the temperature of the fluoro complex ion solution 62, the liquid phase deposition material layer 13 can be formed without using a reaction initiator.

Further, when fine particles of the liquid-phase deposition material are precipitated and suspended in the fluoro complex ion solution 62 in the first bath 52a, the pump 52c is operated to circulate the fluoro complex ion solution 62 through the circulation pipe 52d via the filter 52b. Circulate while filtering. This circulation removes fine particles of the liquid phase deposition material.

The object 10 on which the liquid phase deposition material layer 13 is formed is pulled up from the first bath 52a, the mask 64 is removed, and the object 10 is put into the heating furnace 56a and heated. Note that the heating furnace 56a may not be used. Further, when the heating furnace 56a is used, the temperature of the workpiece 10 becomes high, so the mask 64 may be made of a material that evaporates with the heat of the heating furnace 56a. This is because the trouble of removing the mask 64 is eliminated.

The object to be processed 10 on which the liquid phase deposition material layer 13 is formed is put into the second bath 54 a of the fifth film forming section 84 . A solution (metal ion solution 18) containing the metal ions 18a of the metal film 20 to be formed is stored in the second bath 54a. After being immersed in the second bath 54a, the object 10 to be processed is irradiated with the ultraviolet rays 17 from the ultraviolet light source 85a (sixth film forming step).

Electrons 13e are supplied from the liquid phase deposition material layer 13 by the ultraviolet rays 17, and the metal ions 18a in the metal ion solution 18 are reduced. The reduced metal ions 18a are deposited on the liquid phase deposition material layer 13 to form a metal layer 20b. 20b) can be obtained. As described above, the electronic product 1 having the metal film 20 formed on the processed surface 12 of the processed object 10 is obtained.

After forming the metal film 20, the film may be further increased by plating. The plating at this time may be electroless plating as described above, or electrolytic plating. Either method can be used because the metal film 20 is already formed. This plating is called a film-increasing process.

The method for forming a metal film according to the present invention can be used not only for electronic products such as circuit boards, semiconductor circuits and electronic parts, but also for protective films and decorative finishing films.

1 Electronic product 10 Object to be processed 10a Insulating substrate 10b Metal layer 10h Through hole 10hi Inner wall 10r Rear surface 12 Surface to be processed 12a Cross-sectional portion 12b Cross-sectional portion 13, 13i Liquid phase deposition material layer 13e Electron 18 Metal ion solution 18a Metal ion 14, 14i Mixed layer 16 Reducing solution 17 Ultraviolet ray 19 Mixed metal film 20, 20i Metal film 21 Separated metal film 22 Electroless plated layer 50 Forming device 52 First film forming unit 52a First bath 52b Filter 52c Pump 52d Circulation pipe 52e Reaction Initiator tank 52j Heater 52f Piping 52g Valve 54 Second film forming part 54a Second bath 56 Heating part 56a Heating furnace 60 Reaction solution 61 Reaction solution 62 Fluoro complex ion solution 64 Mask 70 Forming device 74 Third film forming part 74a Irradiation stand 74b Ultraviolet light source 80 Forming device 82 Fourth film-forming unit 84 Fifth film-forming unit 85 Sixth film-forming unit 85a Ultraviolet light source

Claims (29)

A step of forming a coexisting region of a metal ion region in which metal ions are present in a liquid phase and a liquid phase deposition material region in which a liquid phase deposition material is present on the surface of an object to be processed;
A method of forming a metal film, comprising a reduction treatment step of reducing the metal ions to reform the coexisting region into a metal film on the surface to be treated. The step of forming the coexisting region includes:
A reaction solution containing fluoro complex ions, which are raw materials for the liquid phase deposition material, and the metal ions are brought into contact with the surface to be treated to form the coexisting region containing the liquid phase deposition material and the metal ions. including one film formation step,
2. The method of forming a metal film according to claim 1, wherein the reducing treatment step is a second film forming step of bringing a reducing solution into contact with the coexisting region. 3. The method of forming a metal film according to claim 2, further comprising a heating step of heating the object to be processed between the first film forming step and the second film forming step. 4. The method of forming a metal film according to claim 2, wherein said reducing solution is an electroless plating solution. 5. The method of forming a metal film according to any one of claims 2 to 4, further comprising a film-increasing step by plating after the second film-forming step. 6. The metal ion according to any one of claims 2 to 5, wherein the metal ion is at least one selected from the group consisting of gold, palladium, platinum, silver, copper, nickel, and cobalt. A method for forming a metal film. 7. The method of forming a metal film according to claim 2, wherein said reaction solution further contains at least one of borate, aluminum salt and hydrogen peroxide. 8. The formation of the metal film according to any one of claims 2 to 7, wherein the object to be processed is an insulating substrate selected from a resin substrate, a ceramic substrate, a glass substrate, and a silicon substrate. Method. 9. The metal film according to any one of claims 1 to 8, wherein the object to be processed has a metal layer selected from copper, aluminum, and silver formed on an insulating substrate. Forming method. An electronic product on which a metal film of a mixture of oxide and metal is formed on the surface to be treated. A reaction solution containing fluoro complex ions and metal ions is brought into contact with the surface of an object to be treated to form a mixed layer containing the metal ions and a liquid phase deposition material deposited from the fluoro complex ions on the surface to be treated. a first film forming unit to
An apparatus for forming a metal film having a second film forming unit for applying a reducing solution to the mixed layer to reform the mixed layer into a metal film. 12. The apparatus for forming a metal film according to claim 11, wherein the reducing solution is an electroless plating solution. The step of forming the coexisting region includes:
A reaction solution containing fluoro complex ions and metal ions of a photocatalyst material, which is a raw material of the liquid phase deposition material, is brought into contact with the surface to be treated to form the coexisting region containing the liquid phase deposition material and the metal ions. including one film formation step,
2. The method of forming a metal film according to claim 1, wherein the reducing treatment step is a second film forming step of irradiating the coexisting region with ultraviolet rays. 14. The method of forming a metal film according to claim 13, further comprising a heating step of heating the object to be processed between the first film forming step and the second film forming step. 15. The method for forming a metal film according to claim 13, further comprising a film-increasing step by plating after the second film-forming step. 16. The metal ion according to any one of claims 13 to 15, wherein the metal ion is at least one selected from the group consisting of gold, palladium, platinum, silver, copper, nickel, and cobalt. A method for forming a metal film. 17. The metal film according to any one of claims 13 to 16, wherein the reaction solution further contains at least one of borate, aluminum salt, silicate and hydrogen peroxide. Forming method. 18. The formation of the metal film according to any one of claims 13 to 17, wherein the object to be processed is an insulating substrate selected from a resin substrate, a ceramic substrate, a glass substrate, and a silicon substrate. Method. 19. The metal film according to any one of claims 13 to 18, wherein the object to be processed has a metal layer selected from copper, aluminum, and silver formed on an insulating substrate. Forming method. A first film-forming unit for forming a mixed layer of an oxide and the metal ions on the surface to be treated by bringing a reaction solution containing fluoro complex ions of a photocatalyst material and metal ions into contact with the surface to be treated of the object to be treated. When,
An apparatus for forming a metal film having a second film forming unit for irradiating the mixed layer with ultraviolet rays to convert the mixed layer into a metal film. The step of forming the coexisting region includes:
a first film-forming step of forming a layer of the liquid phase deposition material on the surface to be processed by contacting the surface to be processed with a solution containing fluoro complex ions of a photocatalyst material that is a raw material for the liquid phase deposition material; ,
A second film forming step of contacting the layer of the liquid phase deposition material with the solution containing the metal ions,
2. The method of forming a metal film according to claim 1, wherein the reducing treatment step is a third film forming step of irradiating the coexisting region with ultraviolet rays. 22. The method of forming a metal film according to claim 21, further comprising a heating step of heating the object to be processed between the first film forming step and the second film forming step. 23. The method of forming a metal film according to claim 21, further comprising a plating step for adding a metal film after said third film forming step. 24. Any one of claims 21 to 23, wherein the solution containing the fluoro complex ions of the photocatalytic material further contains at least one of borate, aluminum salt, silicate and hydrogen peroxide. The method for forming a metal film described in . 25. Any one of claims 21 to 24, wherein the metal ions in the metal ion solution are at least one selected from the group consisting of gold, palladium, platinum, silver, copper, nickel, and cobalt. A method for forming a metal film according to claim 1. 26. The formation of the metal film according to any one of claims 21 to 25, wherein the object to be processed is an insulating substrate selected from a resin substrate, a ceramic substrate, a glass substrate, and a silicon substrate. Method. 27. The metal film according to any one of claims 21 to 26, wherein the object to be processed has a metal layer selected from copper, aluminum, and silver formed on an insulating substrate. Forming method. An electronic product in which a metal film is formed on a surface of an object to be processed,
The electronic product, wherein the metal film is composed of a continuous film of photocatalyst material directly on the surface to be processed and a metal layer directly on the continuous film of photocatalyst material. a first film forming unit for forming a liquid phase deposition material layer of a photocatalyst material on the surface to be processed of the object to be processed;
a second film forming unit that contacts the liquid phase deposition material layer and the metal ion solution to form a coexisting region on the surface to be processed;
An apparatus for forming a metal film, comprising a third film forming section for irradiating the coexisting region with ultraviolet rays to form a metal layer immediately above the liquid phase deposition material layer.

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