JP3803592B2 - Low resistance transparent conductive film and method for producing the same - Google Patents

Description

表１から明らかなように、本実施例記載の方法によれば、シート抵抗の低い透明導電膜が得られている。このシート抵抗は、対照としてＩＴＯ微粒子を大気中で５００℃で焼結して得られた透明導電膜のシート抵抗(１５〜３０ＫΩ／□)と比べて、極めて低い値であった。
その他の上記透明導電膜形成用金属酸化物微粒子を用いた場合も、上記方法に従えば、低温燒結で同様に低いシート抵抗を有する透明導電膜が得られる。
【００１７】
【発明の効果】
本発明の透明導電膜によれば、多孔質透明導電膜の空孔及び被処理基板と金属酸化物微粒子との空隙が導電性金属酸化物膜で充填されているので、電気抵抗が低く、かつ、被処理基板との密着性も高い。
また、本発明の低抵抗透明導電膜の製造法によれば、低い焼結温度で、焼結後の電気抵抗が小さい薄膜状透明導電膜を簡単な装置で安価に製造することができる。
【図面の簡単な説明】
【図１】 本発明で用いる成膜装置(真空容器)の構成を模式的に示す概略構成図。
【図２】 実施例１で得られた透明導電膜の構造を模式的に示す断面図。
【符号の説明】
１ ヒータープレート ２ 基板
３ 酸素ガス導入パイプ ４ 有機金属化合物ガス導入パイプ
１１ 基板 １２ ＩＴＯ微粒子
１３ インジウム酸化物膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low resistance transparent conductive film and a method for producing the same. The low resistance transparent conductive film can be used as a transparent conductive film for flat panel displays such as LCD and organic EL.
[0002]
[Prior art]
Conventionally, a transparent conductive film for flat panel displays such as LCD and organic EL has been manufactured by depositing a metal oxide on a glass substrate by vapor deposition, ion plating, sputtering, or the like. However, in these methods, since the apparatus becomes large, the apparatus cost increases, and the manufacturing cost increases. Therefore, a method of manufacturing at low cost with a simple apparatus has been demanded.
[0003]
Therefore, in order to manufacture transparent conductive films for flat panel displays at low cost with a simple device, instead of the conventional sputtering film forming method, etc., in recent years, transparent conductive films such as ITO films have been applied by spin coating and spray coating. It has been proposed to form by ink jet coating. In this case, as the transparent conductive film forming material, for example, a dispersion liquid in which fine particles such as ITO are dispersed in an organic solvent is used for coating the CRT surface. The dispersion is applied to the substrate by the above application method and then heated to remove the organic solvent and sinter the ITO fine particles, thereby forming a thin ITO film on the substrate.
[0004]
[Problems to be solved by the invention]
The conventional material used in the above coating method has a large electrical resistance (sheet resistance) after sintering of several kΩ / □ at low temperature heating, and a high electrical resistance during sintering when trying to obtain a low electrical resistance. Since heating (for example, about 300 ° C. or higher) is required, there is a problem that it cannot be used for forming a transparent conductive film in the field of flat panel displays such as LCD and organic EL. Therefore, a transparent conductive film that can be sintered at a low temperature and has a low resistance value and a method for producing the same are demanded.
An object of the present invention is to solve the above-mentioned problems of the prior art, and a method for producing a thin film-like transparent conductive film having a low sintering temperature and a low electrical resistance (sheet resistance) after sintering and the obtained Another object of the present invention is to provide a low resistance transparent conductive film.
[0005]
[Means for Solving the Problems]
In order to obtain a low-resistance transparent conductive film, the present inventors have intensively studied and developed the material and manufacturing process. As a result, the inventors have found a method for producing a low-resistance transparent conductive film that can significantly reduce electrical resistance by low-temperature heating, and have completed the present invention.
The low resistance transparent conductive film of the present invention is obtained by baking fine particles of a metal film for forming a transparent conductive film at 100 to 250 ° C. in a mixed gas atmosphere of a gas containing oxygen or ozone and a metal halide gas or an organometallic compound gas. It has a structure in which the pores in the porous transparent conductive film made of the metal oxide are filled with a metal oxide generated by a reaction between oxygen or ozone and a metal halide or an organometallic compound. If the sintering temperature is less than 100 ° C., it will not sinter sufficiently, and if it exceeds 250 ° C., problems will arise in the manufacturing process of the display.
[0006]
The metal oxide can be appropriately selected and used as long as it is a material usually used when forming a transparent conductive film. For example, it is selected from ITO, ATO, IZO, ZnO, SnO ₂ , CaWO _{4 and the} like. The ones are preferred.
The metal halide gas is preferably selected from indium halide gas and tin halide gas, and the organometallic compound gas is preferably selected from trimethylindium gas and trimethyltin gas.
The thickness of the low resistance transparent conductive film of the present invention is preferably 1 to 20 nm. This is because if the thickness is less than 1 nm, the electrical resistance does not decrease, and if it exceeds 20 nm, the transmittance decreases.
[0007]
In the method for producing a low resistance transparent conductive film of the present invention, a dispersion of metal oxide fine particles for forming a transparent conductive film is applied on a substrate to be processed and sintered in the atmosphere at 150 to 200 ° C. A film is formed, and then the target transparent conductive film is formed by heating at 100 to 250 ° C. in a mixed gas atmosphere of a gas containing oxygen or ozone and a metal halide gas or an organometallic compound.
The metal oxide used in this production method is as described above for the metal halide gas and the organometallic compound gas.
The low-resistance transparent conductive film of the present invention is characterized in that it also has adhesion to a glass substrate or a substrate made of an organic resin material.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
As described above, the low-resistance transparent conductive film of the present invention is a porous transparent conductive film made of a metal oxide obtained by sintering fine particles of a metal oxide for forming a transparent conductive film in a specific mixed gas atmosphere at a low temperature. The vacancies are filled with indium oxide. As described above, this transparent conductive film is prepared by preparing a dispersion of fine particles of metal oxide for forming a transparent conductive film, and applying this dispersion on a substrate to be processed, for example, spin coating, spray coating, inkjet coating, and immersion. Coating is performed using a known method such as coating, roll coating, screen printing, and the like, and is heated at 150 to 200 ° C. in the atmosphere to form a porous transparent conductive film, and then a gas containing oxygen or ozone and halogen In a mixed gas atmosphere with indium phosphide gas or organic indium gas, the temperature is much lower than the temperature (generally, 500 to 700 ° C.) necessary for sintering the fine particles of a normal transparent conductive film forming material alone. It is obtained by forming a film by sintering at ˜250 ° C.).
[0009]
As the metal oxide for forming a transparent conductive film in the present invention, indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide, In ₂ O ₃ (ZnO) _m , ordinarily used as a material for forming a transparent conductive film, and InGaO ₃ (ZnO) _m or the like, and those obtained by adding a dopant to these oxides, for example, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), zinc-doped indium oxide (IZO), and aluminum-doped zinc oxide ( AZO) or the like can be used. As a material for forming a transparent conductive film for displays such as LCD and organic EL, ITO, IZO, zinc oxide, SnO ₂ and CaWO ₄ are particularly preferable.
[0010]
The dispersion in the present invention is obtained by dispersing the metal oxide fine particles in an organic solvent. What is necessary is just to select suitably as an organic solvent to be used with the microparticles to be used, for example, there exist the following. That is, alcohols such as methanol, ethanol, propanol, isopropyl alcohol and butanol, glycols such as ethylene glycol, ketones such as acetone, methyl ethyl ketone and diethyl ketone, esters such as ethyl acetate, butyl acetate and benzyl acetate, methoxy Examples include ether alcohols such as ethanol and ethoxyethanol, ethers such as dioxane and tetrahydrofuran, acid amides such as N, N-dimethylformamide, and aromatic hydrocarbons such as toluene and xylene. Further, in the present invention, the organic solvent includes water.
[0011]
The amount of the organic solvent used may be appropriately selected according to the fine particles to be used so that it can be easily applied in the case of a dispersion and can obtain a desired film thickness. For example, the fine particles are 1 to 10 wt% with respect to the solvent.
Examples of the support as the substrate to be treated on which the dispersion liquid is applied include a glass substrate or a substrate made of an organic resin material, and the shape thereof may be a flat plate, a three-dimensional object, a film, or the like. As the organic resin material, for example, cellulose acetates, polystyrene, polyethylene terephthalate, polystyrenes, polyethers, polyimide, epoxy resin, phenoxy resin, polycarbonate, polyvinylidene fluoride, Teflon, and the like can be used. These may be used alone or in combination as a support. This substrate to be treated is preferably cleaned using pure water, ultrasonic waves or the like before applying the dispersion.
[0012]
Preferable examples of the metal halide gas that is one component of the mixed gas used in the production of the transparent conductive film of the present invention include indium fluoride, indium chloride, indium bromide, and indium iodide gas. The organometallic compound gas may be any gas that reacts with oxygen or ozone, and preferably includes a gas such as trimethylindium or trimethyltin. Further, the gas containing oxygen and ozone may be a gas containing oxygen and ozone in a sufficient amount to react. Further, an inert gas such as argon can be used as a carrier gas for introducing the mixed gas. The component metal of these gases may be the same as or different from the conductive metal of the metal oxide fine particles.
[0013]
Normally, when a heat treatment is performed at a low temperature of about 250 ° C. after applying a metal oxide fine particle dispersion, the metal oxide for forming a transparent conductive film does not sinter sufficiently, and a porous film having small pores is formed. Therefore, a transparent conductive film having a small electric resistance cannot be formed. However, when the heat treatment is performed under the process conditions of the present invention, the vacancies in the produced porous film are filled with, for example, indium oxide produced by the reaction of oxygen or ozone and indium halide gas or organic indium gas. It becomes like this. Therefore, the transparent conductive film is densified and has a small electric resistance. At the same time, since the gap between the metal oxide fine particles and the substrate to be processed is completely filled with this indium oxide, the adhesion between the transparent conductive film and the substrate to be processed is significantly improved compared to the case of the metal oxide alone. To do.
[0014]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
(Example 1)
In ₂ O ₃ fine particles (ITO: particle size of 1 μm or less) to which 5 wt% of Sn was added were dispersed in n-butyl acetate so as to have a concentration of 5% to prepare a dispersion. This dispersion was applied to a glass substrate by spin coating. This substrate was heated in the atmosphere at 200 ° C. for 5 minutes in the atmosphere to form a porous transparent conductive film having a thickness of about 100 nm. Next, this substrate was further heat-treated. That is, after the substrate 2 is installed on the heater plate 1 as a heating mechanism provided in the stainless steel vacuum vessel shown in FIG. 1 and the inside of the vessel is evacuated, the oxygen gas introduction pipe 3 and the organometallic compound gas introduction pipe 4 are provided. Then, oxygen gas and trimethylindium gas were introduced into the container by a bubbling method using argon gas as a carrier gas. The pressure in the container at this time was 90 kPa or less, and the substrate temperature was 250 ° C. Thus, a transparent conductive film having a thickness of about 150 nm was formed. The transparent conductive film thus obtained is densified and has a low electrical resistance as described below.
[0015]
FIG. 2 shows a schematic cross-sectional structure of the obtained transparent conductive film. As shown in FIG. 2, the transparent conductive film formed on the substrate 11 is composed of metal oxide (ITO) fine particles 12 for forming a conductive film, and the pores in the porous film and the metal oxide fine particles 12 are covered. A gap or the like with the processing substrate 11 is filled with an indium oxide film 13 which is a product of a reaction between oxygen and trimethylindium.
In the above production method, the heating time was 3, 5, and 10 minutes, and the sheet resistance (Ω / □) was measured for the transparent conductive film obtained in each heating time. The results are shown in Table 1.
[0016]
(Table 1)

As is apparent from Table 1, according to the method described in this example, a transparent conductive film having a low sheet resistance is obtained. This sheet resistance was a very low value compared with the sheet resistance (15 to 30 KΩ / □) of a transparent conductive film obtained by sintering ITO fine particles in the atmosphere at 500 ° C. as a control.
When other metal oxide fine particles for forming the transparent conductive film are used, a transparent conductive film having a low sheet resistance can be obtained by low-temperature sintering according to the above method.
[0017]
【The invention's effect】
According to the transparent conductive film of the present invention, since the pores of the porous transparent conductive film and the gap between the substrate to be processed and the metal oxide fine particles are filled with the conductive metal oxide film, the electrical resistance is low, and Also, the adhesion to the substrate to be processed is high.
Moreover, according to the manufacturing method of the low resistance transparent conductive film of this invention, the thin film-like transparent conductive film with small electrical resistance after sintering can be manufactured at low cost with a simple apparatus at low sintering temperature.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram schematically showing the configuration of a film forming apparatus (vacuum container) used in the present invention.
2 is a cross-sectional view schematically showing the structure of a transparent conductive film obtained in Example 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heater plate 2 Substrate 3 Oxygen gas introduction pipe 4 Organometallic compound gas introduction pipe 11 Substrate 12 ITO fine particle 13 Indium oxide film

Claims (6)

A porous film made of a metal oxide obtained by sintering fine particles of a metal oxide for forming a transparent conductive film at 100 to 250 ° C. in a mixed gas atmosphere of a gas containing oxygen or ozone and a metal halide gas or an organometallic compound gas. A low-resistance transparent conductive film having a structure in which pores in a porous transparent conductive film are filled with a metal oxide generated by a reaction between oxygen or ozone and a metal halide or an organometallic compound. The transparent conductive film-forming metal _{oxide, ITO, ATO, IZO, ZnO} , low-resistance transparent conductive film according to claim 1, characterized in that selected from SnO 2, CaWO _4. The low resistance transparent conductive film according to claim 1 or 2, wherein the metal halide gas is an indium halide gas or a tin halide gas, and the organometallic compound gas is a trimethylindium gas or a trimethyltin gas. A dispersion of metal oxide fine particles for forming a transparent conductive film is applied onto a substrate to be processed, and sintered in the atmosphere at 150 to 200 ° C. to form a porous transparent conductive film, and then a gas containing oxygen or ozone A method for producing a low-resistance transparent conductive film, wherein the transparent conductive film is formed by heating at 100 to 250 ° C. in a mixed gas atmosphere of an oxygen and a metal halide gas or an organometallic compound gas. The transparent conductive film-forming metal _{oxide, ITO, ATO, IZO, ZnO} , preparation of a low-resistance transparent conductive film according to claim 4, characterized in that selected from SnO 2, CaWO _4. 6. The low-resistance conductive film according to claim 4, wherein the metal halide gas is an indium halide gas or a tin halide gas, and the organometallic compound gas is a trimethylindium gas or a trimethyltin gas. Law.

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