JPH07173610A - Transparent electric conductive ultrathin film and production thereof - Google Patents

Abstract

PURPOSE:To obtain a thin film excellent in transparency, electric conductivity and environmental resistance by depositing a vaporized transition metal on an excited substrate in vacuum. CONSTITUTION:A vaporized transition metal is deposited on an excited substrate of glass, ceramics, an org. polymer, etc., under vacuum to form a thin film of the transition metal and the objective transparent electric conductive ultrathin film having 1-200nm thickness and excellent in environmental resistance is obtd. This film is used for an electrode material for a liq. crystal display device an anti-fogging heating element, the antistatic coating of a cathode-ray tube, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive ultrathin film and a method for manufacturing the same.

[0002]

2. Description of the Related Art Ultra-thin transparent conductive ultra-thin films are widely used for electrodes of displays using liquid crystals, anti-fog heating elements for glass, and the like.

Generally, a transparent conductive ultrathin film is required to have transparency and conductivity as basic characteristics.
Therefore, tin oxide, indium oxide, etc., which are substances having the above characteristics, have been conventionally used as raw materials for the thin film.

However, tin oxide is easily corroded,
Due to lack of environment resistance, the thin film cannot be used, for example, in a portion that comes into contact with outside air. Therefore, its application is extremely limited.

[0005]

Therefore, it is an object of the present invention to provide a transparent conductive ultrathin film which is particularly excellent in environmental resistance.

[0006]

As a result of intensive studies conducted by the present inventor in view of the above problems of the prior art, a specific thin film containing a transition metal has excellent transparency, conductivity and environment resistance. I found that. That is, the present invention provides the following transparent conductive ultra-thin film and its manufacturing method.

1. A transparent conductive ultrathin film having a film thickness of 1 to 200 nm, which is formed on a substrate and contains at least one kind of transition metal.

2. A method for producing a transparent conductive ultrathin film, which comprises depositing at least one vaporized transition metal on a substrate in an excited state in vacuum to form a thin film of the transition metal.

The present invention will be described in detail below.

In the present invention, the substrate is not particularly limited in size, shape and material as long as a thin film can be formed, but glass, ceramics, organic polymers and the like are exemplified.

Examples of the glass include oxide glasses such as silicate glass, borosilicate glass and alkali glass, examples of the ceramics include crystalline oxides such as alumina, magnesia and zirconia, and examples of the organic polymer include organic polymers. , Polyimide, polyethylene, polyvinyl, etc. can be exemplified, and polymethyl methacrylate, Kapton, etc. are preferable. As a particularly preferred substrate material,
Borosilicate glass is mentioned. It is preferable that the substrate has transparency for applications such as an electrode of a display device using a liquid crystal and a heating element for antifogging of glass. A transparent substrate has a light-transmitting property of 10 to 100%, preferably 50.
~ 100%. The translucency is based on the measured value of the transmittance of visible light. The substrate may not be transparent when the thin film is used in applications that do not require transparency, such as antistatic films.

The transparent conductive ultrathin film of the present invention is composed of a transition metal. This transition metal is represented by IB, IIB, IIIB to VII in the periodic table of the Chemical Encyclopedia of Kyoritsu Shuppan Co., Ltd.
It means an element of each group of B and VIIIB and is not particularly limited as long as it is included in these, but preferably titanium, vanadium, chromium, manganese, iron, cobalt, nickel,
Zirconium, niobium, molybdenum, rhodium, palladium, silver, hafnium, tantalum, tungsten, iridium, platinum, gold, metals belonging to lanthanide and actinide are preferable, and titanium and gold are particularly preferable. The transition metal may be present in the thin film as a simple metal, but when an ion beam of carbon, nitrogen, oxygen, hydrogen, etc. is used to excite the surface of the substrate, a part or all of the transition metal is a carbide or a nitride. It may exist in the form of a substance, an oxide, a hydride or the like. The thickness of the thin film is usually about 1 to 200 nm, preferably about 1 to 100 nm. Film thickness is 5
Within the range of 100 nm, it is particularly preferable because it has both conductivity and transparency. Also, the film thickness is 10 to 50 n
Within the range of m, the above-mentioned characteristics are particularly excellent, which is preferable.

The transparent conductive ultrathin film of the present invention often has an amorphous structure, but the proportion of crystalline material may increase depending on the manufacturing conditions. Whether it is amorphous or crystalline, its characteristics are hardly affected. The translucency of the transparent conductive ultrathin film of the present invention is about 30 to 95%, preferably about 50 to 95%, and the conductivity is usually 0.1 to 1%.
It is about 00 kΩ / □, preferably about 1 to 10 kΩ / □. The transparent conductive ultrathin film of the present invention has environmental resistance to the extent that its function is not lost even when it is immersed in an acidic aqueous solution or sprayed with salt water.

Next, the manufacturing method of the present invention will be described. First, the surface state of the substrate on which the thin film is formed is set to the excited state. To excite the substrate surface on which the thin film is formed,
The substrate may be irradiated with an ion beam, plasma, electron beam, laser or the like, but other excited state forming means may be used as long as the surface of the substrate is in an excited state. The irradiation conditions may be appropriately set depending on the type of substrate, the type of transition metal, the desired film thickness, and the like. The “excited state” as referred to in the present invention specifically means that the surface of the substrate is in a state having a larger thermal kinetic energy or a state having a larger internal energy as compared with that before the irradiation of the excitation source.
Ion beam, plasma, electron beam, laser, etc.
The surface of the substrate may be irradiated alone or in combination of two or more kinds.

The surface of the substrate is preferably excited by continuously or intermittently irradiating with an ion beam, plasma, electron beam, laser or the like during vapor deposition. In the case of intermittent irradiation, the irradiation frequency may be 1 Hz or higher, preferably 10 Hz or higher.

Examples of ions used for the ion beam include ions of an inert gas such as helium, neon, argon and krypton, and ions of carbon, nitrogen, oxygen, hydrogen and the like. In particular, when an ion beam of carbon or nitrogen is used, these react with a transition metal to form a carbide or a nitride, which is preferable because the environment resistance of the thin film can be further improved. Electrons may be mixed in the ion beam to be electrically neutral or negative as a whole. The acceleration voltage of the ion beam may be about 10 V or higher, preferably 10 V to 100 kV.

Examples of the plasma include a high frequency system and a direct current system.

Examples of the laser include YAG laser, carbon dioxide gas laser and excimer laser.

In the method of the present invention, a vaporized metal is vapor-deposited on the surface of a substrate in an excited state to form a transparent conductive ultrathin film. The vapor deposition is not particularly limited, and known vapor deposition methods such as a vacuum vapor deposition method, a laser ablation method, an ion plating method, an ion beam deposition method, and a CVD method can be applied.

In the vapor deposition method of the present invention, a transition metal is vapor-deposited in a state where a hydrocarbon gas such as methane or ethane, an organic substance such as ethanol, an inert gas such as helium or argon, or nitrogen or hydrogen is introduced into a vacuum. If it is performed, thin film formation can be further promoted.

[0021]

According to the method for producing a transparent conductive ultra-thin film of the present invention, a vaporized transition metal is vapor-deposited on a substrate in an excited state in a vacuum. Thin films with different properties can be obtained.

Since the transparent conductive ultrathin film of the present invention is a very thin film composed of a transition metal and having a film thickness of 1 to 200 nm, it has excellent transparency and conductivity and excellent environmental resistance. Can also be demonstrated. Therefore, the thin film is not easily oxidized or corroded by salt during use, and can exhibit good transparency and conductivity.

Further, in the manufacturing method of the present invention, when the substrate is continuously kept in an excited state during the vapor deposition, the thin film strongly adheres to the substrate, and the thin film surface is manufactured by another manufacturing method. Smoother than a thin film. Therefore,
According to the present invention, a thin film having excellent environment resistance, transparency and electric conductivity can be manufactured.

The transparent conductive ultra-thin film of the present invention having such characteristics can be used in a wider range of applications than conventional thin films, and can be used not only for electrode materials for liquid crystal display elements and anti-fogging heating elements, but also for the outside air. It is also useful for applications such as antistatic coating of CRTs exposed to light.

[0025]

EXAMPLES Examples and comparative examples of the present invention will be shown below to further clarify the features of the present invention.

To evaluate the environment resistance, a 0.5% sodium chloride aqueous solution is sprayed for 1 hour, and then, if the deterioration of the transparency and the electric conductivity is 10% or less, the environment resistance is excellent. It was judged that there was. Further, if the deterioration of the above value is within the measurement error range and further the deterioration is within the measurement error range even by the immersion test with 0.1N hydrochloric acid aqueous solution, the environmental resistance is particularly excellent. Stipulate.

Example 1 In a vacuum, a fused silica substrate was irradiated with a nitrogen ion beam. Ion beam acceleration voltage is 10k
The V and ion beam current densities were 0.1 mA / cm ² . Simultaneously with the irradiation of the ion beam, titanium was vapor-deposited on the substrate by the electron beam heating method. At this time, the vapor deposition rate was 0.5 nm per second, the vapor deposition time was 20 seconds, and the vapor deposition film thickness was 10 nm.

The obtained titanium-containing thin film had an electric resistance of 5 kΩ / □ on the surface, and it was confirmed that the thin film had conductivity. In addition, since its translucency is 85%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore,
When the thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

In order to evaluate the adhesion of the thin film, an epoxy resin was applied on the thin film, and a stud having a flat top with a diameter of 3 mm was vertically bonded to the substrate, and then the stud was pulled in the vertical direction of the substrate. When the film was pulled with a force of 3N, the thin film did not peel off. Therefore, it is clear that this thin film strongly adheres to the substrate. When the surface roughness of the surface of the thin film was evaluated by an atomic force scanning probe microscope, the surface roughness was 2 nm or less.

Comparative Example 1 For comparison, an attempt was made to form an ultrathin titanium nitride film by vapor deposition in a nitrogen atmosphere without exciting the substrate. 5 x 1
Under a nitrogen partial pressure of 0 ⁻⁵ Torr, titanium was supplied onto the quartz substrate for 40 seconds at a deposition rate of 0.5 nm / second. When this sample was examined, titanium was supplied onto the quartz substrate for 40 seconds. When this sample was examined by an atomic force scanning probe microscope, it had an island structure and had no electrical conductivity. When left in the air for one day, it was oxidized to titanium oxide. Therefore, it is clear that the desired effect cannot be obtained without exciting the substrate.

Example 2 An aluminum oxide single crystal substrate was irradiated with a carbon ion beam in a vacuum. Ion beam acceleration voltage is 10 kV, ion beam current density is 0.1 m
It was A / cm ² . Simultaneously with the irradiation of the ion beam, vanadium was vapor-deposited on the substrate by the electron beam heating method.
At this time, the vapor deposition rate was 1 nm per second, the vapor deposition time was 20 seconds, and the vapor deposition film thickness was 20 nm. At the same time, an excimer laser was irradiated at 50 mJ and 100 Hz.

The surface resistance of the obtained vanadium-containing thin film was 6 kΩ / □, and it was confirmed that the thin film had conductivity. In addition, since its translucency is 75%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore,
When the thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

Example 3 In a vacuum, a transparent acrylic resin plate substrate was irradiated with carbon and hydrogen ion beams. The acceleration voltage of the ion beam was 10 kV, and the current density of the ion beam was 0.01 mA / cm ² . Simultaneously with the irradiation of the ion beam, gold was deposited on the substrate by the electron beam heating method. At this time, the vapor deposition rate was 0.1 nm per second, the vapor deposition time was 100 seconds, and the vapor deposition film thickness was 10 nm.

The electric resistance of the surface of the obtained gold-containing thin film is 1
It was kΩ / □, and it was confirmed to have conductivity. In addition, since its translucency is 70%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore, when the above thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

Example 4 YA was applied to a magnesium oxide substrate in vacuum.
The G laser was irradiated at an intensity of 100 mW. Simultaneously with laser irradiation, zirconium was vapor-deposited on the substrate by an electron beam heating method. The vapor deposition rate was 0.5 nm per second, the vapor deposition time was 100 seconds, and the vapor deposition film thickness was 50 nm. Also,
Nitrogen gas was introduced into the vacuum container during vapor deposition, and the pressure was set to 1 × 10 ⁻⁴ Torr. Formed by this,
The surface resistance of the zirconium nitride thin film is 3 kΩ / □,
It was confirmed to have conductivity. In addition, since its translucency is 70%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore, when the above thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

Example 5 10 parts per borosilicate glass substrate in vacuum
Argon ions accelerated at kV are 0.05 mA / cm
Irradiation was performed at a current density of ² . Hafnium was vapor-deposited on the substrate simultaneously with the irradiation of the ion beam by the electron beam heating method. The vapor deposition rate was 0.5 nm per second, the vapor deposition time was 100 seconds, and the vapor deposition film thickness was 50 nm. The vacuum degree at this time was 1 × 10 ⁻⁴ Torr, of which 5 × 10 ⁻⁵
Torr was the partial pressure due to the introduction of nitrogen. The surface resistance of the hafnium nitride thin film formed by this is 10
It was kΩ / □, and it was confirmed to have conductivity. In addition, since its translucency is 55%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore, when the above thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

Example 6 In a vacuum, 20k was applied to an alkali glass substrate.
Helium ions accelerated by V were irradiated at a current density of 0.1 mA / cm ² . Simultaneously with the irradiation of the ion beam, tungsten was vapor-deposited on the substrate by the electron beam heating method. The vapor deposition rate was 0.5 nm per second, the vapor deposition time was 100 seconds, and the vapor deposition film thickness was 20 nm. The vacuum degree at this time was 1 × 10 ⁻⁴ Torr, of which 5 × 10 ⁻⁵
Torr was the partial pressure due to the introduction of methane gas. The surface resistance of the tungsten carbide thin film formed by this was 40 kΩ / □, and it was confirmed to have conductivity. In addition, since its translucency is 70%, it was confirmed that the thin film was a transparent conductive thin film. Furthermore,
When the thin film was subjected to a sodium chloride aqueous solution spray test and a hydrochloric acid aqueous solution immersion test, it was confirmed that there was no change in its transparency and conductivity and that it was particularly excellent in environmental resistance.

[Procedure amendment]

[Submission date] August 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

Comparative Example 1 For comparison, an attempt was made to form an ultrathin titanium nitride film by vapor deposition in a nitrogen atmosphere without exciting the substrate. 5 x 1
Under a nitrogen partial pressure of 0 ⁻⁵ Torr, titanium was supplied onto the quartz substrate for 40 seconds at a deposition rate of 0.5 nm / second. When this sample was examined by an atomic force scanning probe microscope, it had an island structure and had no electrical conductivity. When left in the air for one day, it was oxidized to titanium oxide. Therefore, it is clear that the desired effect cannot be obtained without exciting the substrate.

Claims (2)

[Claims] 1. A transparent conductive ultrathin film having a film thickness of 1 to 200 nm, which is formed on a substrate and contains at least one kind of transition metal. 2. A method for producing a transparent conductive ultrathin film, which comprises depositing at least one vaporized transition metal on a substrate in an excited state in vacuum to form a thin film of the transition metal.