Patent Application
20080311414
1. Field of the Invention
The present invention concerns a forming method of keeping goods adhesion between a thin metal film and a substrate, and a thin metal film prepared by the forming method.
2. Description of the Related Art
In recent years, micro-fine metal particles mixed and dispersed to an organic solvent and a resin into a paste have high fluidity like an ink and can form a thin metal film by a simple and convenient method of merely coating and baking on a substrate. A synthesis method of micro-fine metal particles is generally classified into three methods that are a solid phase method, a liquid phase method, and a gas phase method. Among them, since the solid phase method including pulverization has a limit in fine particulation, the liquid phase method and the gas phase method are suitable to the synthesis of micro-fine particles. An in-gas evaporation method as a typical gas phase method is a method of heat melting a metal and evaporating the same under vacuum being carrying on an inert gas, followed by coagulation. The liquid phase method is a method of adding a precipitating agent and water to a solution containing a metal salt thereby taking place a chemical reaction and forming fine particles by nuclear formation and growing of the resultant material, in which the resultant micro-fine metal particles are converted into a stable colloidal system without growing. For preparing a paste from the ultra-fine particles, it is important how to disperse the resultant micro-fine particles independently without coagulation, and a dispersion method of forming an organic molecular layer on the surface of the ultra-fine particles is mainly used. Particularly, since metal particles of several nm to several tens nm have a large surface area, they are highly active and are melted at a temperature lower than the inherent melting point of the metal.
Then, it has been attempted to manufacture a circuit substrate of forming a pattern on a substrate by using a paste containing the ultra-fine particles dispersed therein. However, since the thin metal film using ultra-fine particles of noble metals such as Ag, or Au less reacts with a smooth substrate and no sufficient adhesion cannot be obtained, there are disclosed, for example, of coating a paste containing ultra-fine metal particles dispersed therein on a glass substrate and then conducting baking at a temperature of 250° C. or higher and 300° C. or lower, thereby forming a thin metal film on the glass substrate, in which a silane coupling agent is used (for example, refer to JP-A-2004-175646 and JP-A-2004-179125).
However, even if the silane coupling agent is used, when baking is conducted at a temperature of 250° C. or higher and 300° C. or lower, the coupling agent is decomposed into silicon oxide and while this has close adhesion with a smooth substrate, sufficient adhesion cannot be obtained for a thin metal film using fine particles of a noble metal such as Ag or Au with the silicon oxide to result in a problem that metal wirings are peeled from a substrate, particularly, in a case of forming a metal plating film on thin metal wirings for increasing the conductivity, by a plating pretreatment or chemical treatment with a plating solution. Further, while there has been a method of forming unevenness on the surface of a smooth substrate by using chemicals or physical means and ensuring adhesion by an anchoring effect, this also resulted in a problem that no sufficient highly fine pattern can be obtained due to the presence of the physical unevenness on the surface of the substrate.
The present invention has been achieved in view of the above and it intends to provide a method of forming a metal film in which the metal film using fine metal particles on a smooth substrate is less peeled from the substrate, as well as a metal film prepared by the forming method. Further, the invention intends to provide a method of forming a metal film having good adhesion in which metal wirings are not peeled from a substrate even by a plating pretreatment or a chemical treatment with a plating solution upon forming a thin metal plating film on the metal wirings formed on the substrate for increasing the conductivity, as well as a metal film prepared by the forming method.
For solving the subject described above according to the invention, a coupling agent containing a metal element to be transformed to an oxide and a fine metal particle layer formed by applying a liquid containing fine metal particles dispersed therein are formed successively on the surface of a substrate and then temperature is elevated to a temperature where fine metal particles are metallized thereby forming a metal film layer.
The present invention can provide a method of forming a metal film capable of forming a metal film layer having good adhesion in which the metal film layer is not peeled from a substrate even by a plating pretreatment or chemical treatment with a plating solution upon forming a metal plating film on a metal film layer for increasing the conductivity.
Preferred embodiments of this invention will be described below.
Then, as shown in
The material for the under-layer 2 includes metals and metal oxides having affinity both with the thin metal film layer 5 comprising noble metal such as silver or gold and the inorganic oxide substrate 1 such as of glass. In this case, the metal can improve the adhesion with the thin metal film layer 5 by forming a diffusion layer with the thin metal film layer 5 by diffusion or the like. Further, in a case of using, for example, a glass substrate for the inorganic oxide substrate 1, since the surface of the glass substrate is constituted with silicon oxide and hydroxyl groups, the metal oxide reacts with the hydroxyl groups to improve the adhesion with the glass substrate. As described above, by way of the under-layer 2, adhesion between the inorganic oxide substrate 1 such as the glass substrate and the thin metal film layer 5 can be kept favorably. The metal for the under-layer includes, for example, titanium, zirconium, and aluminum. For uniformly applying the underlying layer metal on the surface of the inorganic oxide substrate 1 a compound having a structure of a coupling agent can be used suitably and, for example, a titanate type coupling agent, zirconium type coupling agent, and aluminum type coupling agent can be used.
The under-layer 2 is formed by dissolving the materials described above into an appropriate solvent, for example, methanol, ethanol, or toluene to prepare a coating solution and coating the coating solution on the surface of the inorganic oxide substrate 1 by using a coating method such as spin coating, dip coating, or bar coating.
The under-layer 2 is decomposed and oxidized at a temperature of metallizing ultra-fine metal particles of about 200° C. to 400° C. to partially form a metal oxide. For forming the under-layer 2, the metal oxide may be formed partially by a heat treatment of metallizing micro-fine metal particles to be described later, or the under-layer 2 may be previously transformed partially into a metal oxide by various heating devices before metallizing the micro-fine metal particles.
Further, the titanate type coupling agent, the zirconium-type coupling agent, and the aluminum-type coupling agent may be used in admixture.
Then, as shown in
Then, as shown in
Then, for increasing the conductivity of the thin metal film layer 5 obtained in
This Embodiment 1 has an effect capable of forming the thin metal film layer 5 of good adhesion on the smooth inorganic oxide substrate 1. Further, it has an effect capable of forming the plating layer 6 on the thin metal film layer 5 and increasing the conductivity of the thin metal film layer 5 without peeling the thin metal film layer 5 from the inorganic oxide substrate 1 even by applying the plating treatment or the chemical treatment with the plating solution after forming the thin metal film layer 5.
That is, since adhesion between the inorganic oxide substrate 1 and the thin metal film layer 5 is improved by the under-layer 2, peeling of the thin metal film layer 5 from the inorganic oxide substrate 1 can be prevented even when plating is applied over the thin metal film layer 5.
Further, the ultra-fine metal particles comprise an elemental metal and have an effect capable of improving the adhesion with the inorganic oxide substrate also for wirings using the elemental metal.
Further, the elemental metal comprises silver or gold and has an effect capable of improving adhesion with the inorganic oxide substrate also for wirings using an elemental metal of low resistivity.
Then, as shown in
Then, as shown in
Then, as shown in
According to Embodiment 2, since the laser light is irradiated only at the position intended to form the thin metal film pattern 8 of the micro-fine metal particle layer 3, the metallizing treatment for the micro-fine metal particle layer 3 and the wiring pattern forming treatment for the thin metal film layer 5 can be conducted simultaneously to provide an effect capable of shortening the treating step for forming the thin metal film pattern 8 in addition to the effect of Embodiment 1.
Examples of the present invention are to be described below.
A thin metal film was formed by the method shown in
After cleaning the obtained thin silver film by a pretreatment step of alkali degreasing and acid activation, a copper plating film was formed as a plating layer 6 on the thin silver film. Plating was conducted by using a soluble anode of a copper ingot contained in an anode bag, at a room temperature and at a current density of 2 A/dm2 for 136 sec by stirring with a stirrer to obtain a copper plating film of 1 μm.
Acecleans (trade name of products, manufactured by Okuno Chemical Industries Co.; 60 g/L) was used for alkali degreasing, an aqueous solution of 5 wt % sulfuric acid was used for acid activation, and 70 g/L of copper sulfate, 200 g/L of sulfuric acid, 50 mg/L chlorine ions, and 4 mL/L of an additive (Toprutina MKN-M (trade name of products) manufactured by Okuno Chemical Industry Co.) were used for a copper plating bath. For the thin metal film obtained by the treatment described above, a cross-cut tape peeling test was conducted.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using titanium acetyl acetonate (ORGATIX TC-401 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using titanium bis(ethylhexoxo)bis(2-ethyl-3-hydroxyhexoxide) (ORGATIX TC-200 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using diisopropoxy titanium bis(triethanolaminate) (ORGATIX TC-400 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using tetra-n-butoxy zirconium (ORGATIX ZA-65 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using an aluminum compound (ORGATIX AL-80 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent, and a 1:1 solution of 2-propanol and toluene as a dilution solvent.
A thin metal film was formed and the test was conducted by the same method as in Example 1 except for using a fine gold particle ink formed by dispersing a fine particle ink in toluene (Au1T (trade name or products) manufactured by ULVAC Materials Inc.) and changing the heating temperature to 400° C.
A thin metal film was formed by the method shown in
After cleaning the obtained thin silver film pattern by a pretreatment step of alkali degreasing and acid activation, a copper plating film was formed as a plating layer 6 on the thin silver film pattern. Plating was conducted by using a soluble anode of a copper ingot contained in an anode bag at a room temperature and at a current density of 2 A/dm2 for 136 sec by stirring with a stirrer to obtain a copper plating film of 1 μm.
Acecleans (trade name of products, manufactured by Okuno Chemical Industries Co., 60 g/L) was used for alkali degreasing, an aqueous solution of 5 wt % sulfuric acid was used for acid activation, and 70 g/L of copper sulfate, 200 g/L of sulfuric acid, 50 mg/L of chlorine ions and 4 mL/L of additive (Toprutina MKN-M (trade name of products) manufactured by Okuno Chemical Industries Co.) were used for a copper plating bath. By the treatment described above, a good copper plating film was formed with no peeling of the thin silver film pattern also during copper plating. Then, a cross-cut tape peeling test was conducted for the obtained thin metal film.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using titanium acetyl acetonate (ORGATIX TC-401 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using titanium bis(ethylhexoxo)bis(2-ethyl-3-hydroxyhexoxide) (ORGATIX TC-200 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using diisopropoxy titanium bis(triethanolaminate) (ORGATIX TC-400 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using tetra-n-butoxy zirconium (ORGATIX ZA-65 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using an aluminum compound (ORGATIX AL-80 (trade name of products) manufactured by Matsumoto Chemical Industry Co.) as the coupling agent and a 1:1 solution of 2-propanol and toluene as a dilution solvent.
A thin metal film was formed and the test was conducted by the same method as in Example 8 except for using a fine gold particle ink formed by dispersing a fine particle ink in toluene (Au1T (trade name or products) manufactured by ULVAC Materials Inc.) and changing the scanning rate of the laser light to 4 mm/sec.
A thin metal film was prepared and the performance was compared in the same method as in Example 1 except for not applying the coating treatment of the coupling agent on the glass substrate.
A thin metal film was formed and the performance was compared in the same method as in Example 1 except for using hexyl trimethoxy silane (TSL8241 (trade name of products), manufactured by GE Toshiba Silicon Co., Ltd.) as the coupling agent.
A thin metal film was formed and the performance was compared in the same method as in Example 1 except for using 3-aminopropyltriethoxy silane (TSL8331 (trade name of products), manufactured by GE Toshiba Silicon Co., Ltd.) as the coupling agent.
A thin metal film was formed and the performance was compared by the same method as in Example 8 except for not applying the coating treatment of the coupling agent on the glass substrate.
A thin metal film was formed and the performance was compared in the same method as in Example 8 except for using hexyl trimethoxy silane (TSL8241 (trade name of products), manufactured by GE Toshiba Silicon Co., Ltd.) as the coupling agent.
A thin metal film was formed and the performance was compared in the same method as in Example 8 except for using 3-aminopropyltriethoxy silane (TSL8331 (trade name of products), manufactured by GE Toshiba Silicon Co., Ltd.) as the coupling agent.
(Table 1) shows the result of evaluation for the adhesion by a cross-cut tape peeling test in (Examples 1 to 14) and (Comparative Examples 1 to 6) described above.
As shown in (Comparative Examples 1 to 6), in a case of not coating the coupling agent as the pretreatment agent or in a case of using Si type coupling agent, adhesion between the thin metal film and the inorganic oxide substrate 1 by way of the coupling agent is not good.
On the other hand, as shown in (Examples 1 to 14) according to the invention, by using the coupling agent comprising a metal having good adhesion both with the thin metal film and the inorganic oxide substrate 1, when the plating pretreatment or the chemical treatment by the plating solution is conducted upon forming the metal plating film on the thin metal film layer 5 or the thin metal film pattern 8 for improving the conductivity, it is not peeled from the inorganic oxide substrate 1 of a planar surface and a thin metal film having good adhesion can be formed.
Further, when compared with a product, for example, as described in SEI technical Review, No. 168, pages 91-92 in March, 2006, in which adhesion is intended to be improved between the glass substrate and the thin metal film comprising an Ag alloy using the Ag alloy comprising Ag mixed with a different metal by baking at 300° C. for a long time of 30 min, treatment can be conducted in a short time of 2 min at 300° C. after forming the under-layer 2 of the coupling agent of the metal to the inorganic oxide substrate 1 and after coating the fine silver particle on the inorganic oxide substrate 1 as described above.
As described above, by forming a material having a metal element to be transformed to an oxide containing an element such as titanium, zirconium, and aluminum as the coupling agent and having good adhesion both with the inorganic oxide substrate and the thin metal film as the under-layer to the inorganic oxide substrate and utilizing the same as the intermediate layer between the inorganic oxide substrate and the thin metal film, the thin metal film is less peeled from the inorganic oxide substrate and a thin metal film having good adhesion can be formed.
This application is based upon and claims the benefit of priority of Japanese Patent Application No 2007-158267 filed on 2007 Jun. 15, the content of which are incorporated herein by reference in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2007-158267 | Jun 2007 | JP | national |
