JP2002371355A - Method for manufacturing transparent thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a transparent thin film having a high visible light transmittance in a short wavelength region as a method for producing a transparent thin film by a sputtering method. SOLUTION: In producing a transparent thin film by a sputtering method, sputtering is performed such that constituent atoms of a sputtering gas contained in the thin film become 0.05 atomic% or less. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a transparent thin film by a sputtering method, in particular, to a wavelength of 400 to 450.
The present invention relates to a method for producing a transparent thin film having a high visible light transmittance of 10 nm.

[0002]

2. Description of the Related Art Transparent thin films are widely used at present, such as antireflection films, optical filters, surface protection films, gas barrier films, transparent electrodes, transparent heat ray reflection films, and transparent electromagnetic wave shielding films. Among them, a transparent thin film made of a metal oxide containing indium oxide as a main component and a small amount of tin oxide added is ITO (Indium Tin Oxid).
e) called thin film, because of its high transparency and electrical conductivity
As a transparent conductive film material, it is widely applied to a transparent electrode for a display, a transparent conductive film for a touch panel, a transparent electromagnetic wave shielding film for a display, and the like.

[0003] These transparent thin films are mainly produced by vacuum evaporation,
The film is formed by a vacuum process such as an ion plating method and a sputtering method. Among these vacuum processes, the sputtering method has excellent controllability of the film thickness, and can form a high-quality thin film uniformly over a large area.
Widely applied.

[0004] In response to recent demands for cost reduction and weight reduction, a technique of continuously forming these transparent thin films on a plastic film by a roll-to-roll method has already been established. Further, in the case of transparent conductive films, further reduction in resistance and higher transmittance have been pursued.
Japanese Patent Application Publication No. 00-144379 discloses a method in which the amount of oxygen introduced and the amount of moisture that can reduce the specific resistance by heating after forming an ITO film are found, and the ratio is controlled within a delicate range. Research reports for realizing low resistance are not limited to this, and many more have been made.

[0005] The ITO thin film sputtered by the usual method has a slight light absorption on the short wavelength side (380 to 450 nm) of visible light, and exhibits a subtle brown or yellowish tint. Light absorption is closely related to the film formation method, film quality, electric conductivity, and the like. Japanese Patent No. 1685120 discloses a method in which heat treatment is performed after film formation and crystallization is performed to reduce light absorption, that is, improve transmittance. Hamb
erg et al. (J. Appl. P
hys. , Vol. 60, no. 11,1 Decem
ber 1986) includes an improvement in carrier density,
That is, when the specific resistance is reduced, the apparent energy band gap is widened, and the Burstein-Moss effect in which the light absorption edge shifts to a shorter wavelength side is described.

However, a method of crystallizing by applying a heat treatment after the ITO film formation requires a long-time heat treatment at 120 ° C., preferably 150 ° C. or more, which not only complicates the manufacturing process but also increases the plastic The film is greatly curled due to the thermal deformation of the film.
The TO thin film itself has problems such as the occurrence of microcracks and an increase in the surface resistance value, and the low molecular components of the plastic film are deposited on the surface, and the transparency of the substrate itself is impaired.

In the method of increasing the transmittance on the short wavelength side by increasing the carrier density, it is necessary to always keep the stoichiometric composition of the ITO thin film at an optimum level. There is a problem that the transmittance slightly changes due to a change in the carrier density due to the fluctuation. Also, fundamentally, even if an ITO thin film having the highest carrier density is produced by ordinary reactive sputtering, the transmittance on the short wavelength side is not always satisfactory enough.

In the first place, it is reported that the energy band gap of indium oxide is 3.5 eV or more even if the Burstein-Moss effect is ignored. This corresponds to approximately 355 nm in light wavelength. Therefore, if the indium oxide is completely crystallized, light absorption or the like should not appear in the visible light region. However, since an actual ITO thin film is not completely in a crystalline state like a Si single crystal, it is considered that band tilt is generated and light absorption is expressed in an energy region equal to or smaller than a band gap.

[0010] Further, the addition of tin oxide which is a dopant causes lattice defects or the indium oxide itself originally has a lattice structure in which lattice defects such as oxygen vacancies are easily formed. Energy levels are created. Therefore, when considering an actual ITO thin film, the effects of crystallinity, impurity levels, stoichiometric composition ratio, carrier density, and the like affect each other in a complicated manner, and as a result, the transmittance, especially on the short wavelength side, At present, no effective measures have been found to improve the quality.

[0010]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention has been developed as a method for producing a transparent thin film by a sputtering method, in particular, a transparent thin film comprising a metal oxide containing indium oxide as a main component. It is an object of the present invention to provide a method for producing a transparent thin film having a high light transmittance, and a method for producing the above transparent thin film with high productivity.

[0011]

Means for Solving the Problems In the sputtering method,
In general, argon ions, which are a sputtering gas, are accelerated by a discharge voltage at the time of sputtering and, when colliding with the surface of a target, strike out target constituent atoms to form a thin film on a substrate. Argon ions that hit the target with high energy receive electrons,
At the same time as neutral argon atoms, they collide with the substrate at high energy as recoil argon atoms. This phenomenon is remarkable especially when a target material having an atomic weight larger than that of argon atoms is used, and indium is exactly equivalent thereto.

It is well known that argon implanted into a film as described above causes lattice defects and causes lattice distortion and the like. For example, in Japanese Patent Application Laid-Open No. Hei 7-258827, when a metal thin film is formed by a sputtering method, instead of argon as a sputtering gas,
Atomic weight, using a large atomic radius krypton, reduce the recoil atoms bombarded in the film, reduce the lattice strain of the metal thin film, thereby producing a method of producing a metal thin film of low resistivity. I have.

The present inventors have paid attention to the amount of recoil atoms taken into the film and examined the relationship between the amount and the transparency of the film. As the amount of argon contained in the film was smaller, the shorter the wavelength, the shorter the wavelength range. It was found that when the transmittance was improved and the amount of argon was 0.05 atomic% or less in the film, the transmittance on the short wavelength side was high, and a transparent thin film free from yellowing or the like was obtained. This is presumably because the recoil atoms implanted in the film have a large effect on the energy band gap, band tilt characteristics, impurity levels, and the like as lattice defects. The above publication of producing a metal thin film having a low specific resistance using krypton does not show the relationship between the recoil atoms and the transmittance.

As a method of reducing recoil atoms to be injected into the transparent thin film, a method of increasing the pressure during sputtering to reduce the mean free path of the recoil atoms, increasing the number of collisions between particles, and reducing the energy thereof. Can be considered.
However, this method increases the number of collisions of the actually deposited particles to be sputtered, so that the density of the formed film decreases, and the film becomes a porous film, and the refractive index decreases. In the case of a moisture-proof film, the moisture-proof property is reduced.
In addition, if the sputtering power is reduced to form a thin film at a low deposition rate, the energy of the recoil atoms is also reduced, so that the amount of recoil atoms implanted in the film should be reduced. However, according to this method, a thin film cannot be manufactured with high productivity because the film formation rate is significantly reduced.

From these facts, it is desirable that the pressure during sputtering is 0.5 Pa or less. In this case, the mean free path of the sputtered particles sufficiently exceeds the distance between the target and the substrate, and the density of the film decreases. Without forming a dense thin film. Further, the sputtering power is in the normal is about ² per 3W / cm target area, from the viewpoint of film productivity, not good is to lower than the above, that a 4W / cm ² or more large power rather Desirably, in this case, the film-forming speed can be improved almost in proportion to the electric power, so that the productivity of the thin film can be improved.

On the other hand, when a film is formed with such a low sputtering pressure and a high sputtering power exceeding 4 W / cm ² , a considerable amount of recoil atoms are usually implanted, and a thin film having a low transmittance on the short wavelength side is formed. I will. The present inventors have further studied to overcome this problem. As a result, when forming a film under the above conditions, if the discharge voltage is set to a low value of 400 V or less, the amount of recoil atoms injected into the film is reduced. Can be suppressed. That is, the discharge voltage corresponds to an acceleration voltage at which argon ions collide with the target,
When the discharge voltage is reduced, the kinetic energy of the recoil atoms is also reduced, and the amount of argon injected into the film is reduced.

As described above, the present inventors have a great relationship between the amount of the argon gas used as a sputtering gas incorporated as an impurity in the thin film and the transmittance on the short wavelength side. When the content of argon, which is an atom, is set to 0.05 atomic% or less in the film, a transparent thin film having high transmittance, particularly on the short wavelength side, and free from yellowing can be obtained. In addition, as a method for producing this transparent thin film, the pressure during sputtering is 0.5 Pa or less, the sputtering power is 4 W / cm ² or more per target area, and the discharge voltage at that time is 40
It has been found that the above transparent thin film can be manufactured with high productivity by performing a sputtering operation while maintaining the voltage at 0 V or less, and the present invention has been completed.

That is, the present invention is characterized in that, when producing a transparent thin film by a sputtering method, sputtering is performed such that the constituent atoms of a sputtering gas contained in the thin film become 0.05 atomic% or less. The present invention relates to a method for producing a transparent thin film, in which the sputtering gas is argon gas, and the constituent atoms are argon, and the transparent thin film is formed from a metal oxide, a metal sulfide, a metal nitride or a metal halide. The present invention relates to the above-mentioned production method, the above-mentioned production method in which the transparent thin film is made of a metal oxide containing indium oxide as a main component, and the above-mentioned production method in which a plastic film is used as a transparent substrate and a transparent thin film is produced thereon.

Further, according to the present invention, as the above-mentioned production method, a sputtering target is applied under a pressure of 0.5 Pa or less.
By applying a sputtering power of 4 W / cm ² or more per target area and performing a sputtering while maintaining a discharge voltage at that time at 400 V or less, the content of constituent atoms of the sputtering gas is 0.05 atomic% or less. The present invention can provide the above-described production method for producing a transparent thin film. Further, the present invention can provide a transparent thin film having a content of constituent atoms of the sputtering gas produced by these methods of 0.05 atomic% or less.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sputtering method according to the present invention includes an RF (high frequency) magnetron sputtering method,
DC (direct current) magnetron sputtering method, pulse D
There are a C magnetron sputtering method, a dual magnetron sputtering method and the like. When the sputtering target is made of a conductive material such as a metal oxide containing indium oxide as a main component, a DC sputtering method is possible, and a transparent thin film can be manufactured with high productivity using a simple and inexpensive power source, which is particularly preferable.

In the present invention, the sputtering gas includes
Commonly used inert gases such as argon, xenon, and krypton can be widely used, but a particularly preferred sputtering gas is argon gas. As a sputtering atmosphere, together with such a sputtering gas, a gas component for introducing a small amount of an oxygen gas as a reactive gas to correct the stoichiometric composition of the transparent thin film, or for reducing a discharge voltage during sputtering. And moisture can be introduced.

As the sputtering target in the present invention, as a transparent thin film, metal oxide, metal sulfide,
A material capable of forming a metal nitride or a metal halide, particularly a material capable of forming a transparent thin film made of a metal oxide containing indium oxide as a main component is used. For this, a material such as the above-mentioned metal oxide is usually used as it is, but in some cases, a metal material may be used, and this may be formed into a transparent thin film made of a metal oxide or the like by reactive sputtering. .

The production of the transparent thin film in the present invention is usually carried out by a method of forming a film on a transparent substrate. As the transparent substrate, any material can be used as long as it has transparency in the visible light region and has a somewhat smooth surface. Other than a film such as a glass plate, a polymethyl methacrylate (PMMA) plate, or a polycarbonate plate, a transparent thin film may be continuously formed on a transparent substrate while running the transparent substrate to improve the productivity. In order to increase the value, it is desirable to use a plastic film.

As such a plastic film, a polymer film made of polyethylene terephthalate, triacetyl cellulose, polyethylene naphthalate, polyethersulfone, polycarbonate, polyacrylate, polyetheretherketone, polypropylene, polystyrene, polyimide or the like is used. But,
It is not limited to these. The thickness is not particularly limited as long as no problem such as thermal wrinkles occurs in the dry process, but is preferably 10 to 250 μm.

Further, a hard coat layer may be provided on one or both surfaces of such a transparent substrate, or another layer may be provided for adjusting the optical characteristics. The surface condition and configuration of the transparent substrate are particularly limited. There is no. The surface of the transparent substrate may be previously subjected to an etching treatment such as a sputtering treatment or a corona treatment, or an easy-adhesion layer for improving the adhesion between the transparent thin film and the transparent substrate may be formed.

In the present invention, the above-mentioned transparent substrate is mounted in a sputtering apparatus, and the above-mentioned sputtering target is mounted in a position opposite to the above-mentioned transparent substrate. To adjust the pressure to 0.5 Pa or less, preferably 0.3 Pa or less (generally, up to 0.05 Pa). In this state,
4 W / cm ² or more per target area, preferably 5 W
/ Cm ² or more (usually up to 10 W / cm ² ). At this time, the transparent substrate may be heated or cooled, and can be set to an optimum temperature in consideration of film forming conditions, heat resistance of the transparent substrate, and the like.

According to the present invention, the above-mentioned sputtering is carried out at a discharge voltage of 400 V or less, preferably 38 V or less.
It is important to keep the voltage at 0 V or less (usually up to 250 V or more). This makes it possible to easily reduce the number of recoil atoms injected into the transparent thin film formed on the transparent substrate,
The content of the constituent atoms of the sputtering gas aimed at by the present invention, typically, the content of argon, which is a constituent atom of the argon gas, is 0.05 atomic% or less, preferably 0.01 atomic% or less in the thin film. More preferably, it can be made to contain almost no content.

Here, as a method of reducing the discharge voltage to 400 V or less, there is a method of introducing a gas that reduces the discharge start voltage into a sputtering gas such as an argon gas as a typical example. In addition, when moisture is introduced into the sputtering apparatus, the moisture is adsorbed on the surface of the sputtering target and lowers the work function of the target material, so that the effect of lowering the discharge voltage can be obtained. These introduced components do not need to be gaseous under a normal atmosphere, and may be introduced by vaporizing a liquid typified by moisture or by incorporating them in an argon gas or the like, and are not particularly limited.

As another method, see Sugisato et al. [Y. Sugisato at al. J. Appl.
Phys. 71 (7), 1 1992] shows the relationship between the magnetron intensity and the sputtering voltage and the I produced under each condition.
As reported on the electrical conductivity of the TO film, a method of increasing the magnetic force of the magnetron is also effective. Further, as disclosed in JP-A-8-325727,
A low voltage sputtering method using microwave plasma in an auxiliary manner is also effective.

According to the facing target type sputtering apparatus disclosed in Japanese Patent Application Laid-Open No. 10-46330, the collision of recoil atoms with the film formation surface is reduced, and the amount of argon implanted into the film can be reduced. It is expected that there is.
Therefore, this method may be used instead of the above-described method of reducing the discharge voltage, or both methods may be used in combination so that the argon content is 0.05 atomic% or less in the thin film.

The transparent thin film thus produced is made of a metal oxide, a metal sulfide, a metal nitride or a metal halide according to the type of the sputtering target, and particularly preferably a metal oxide containing indium oxide as a main component. When the constituent atoms of the sputtering gas contained in the film are 0.05 atomic% or less, the visible light transmittance, particularly in a short wavelength region of 400 to 450 nm, is high. It has a clear tint with little yellowing or the like. The thickness of the transparent thin film can be appropriately selected depending on the purpose of use and the like, and is not particularly limited.
μm is preferred.

As the metal oxide constituting the transparent thin film,
In addition to those containing indium oxide as a main component, examples thereof include tin oxide, titanium dioxide, cerium oxide, zirconium oxide, zinc oxide, tantalum oxide, niobium pentoxide, silicon dioxide, aluminum oxide, and magnesium oxide. Other than these metal oxides, metal sulfides such as zinc sulfide, metal nitrides such as silicon nitride, and metal halides such as magnesium fluoride can be given.

In the present invention, in order to know the constituent atoms (for example, the content of argon) of the sputtering gas in the transparent thin film, it is necessary to read the book “Sputtering Phenomenon” by Kanbara (The University of Tokyo Press, 1984) ), The amount of gas released is measured using a mass spectrometer by utilizing the release of gas by heating, or by using fluorescent X-rays or EPMA.
(Electron Probe Microanal
ysis), it can be known by performing a composition analysis. The transparent thin film to be analyzed is 100 nm or less, 50
Even if it is less than nm, X-ray fluorescence analysis and the like using the total reflection method have been developed, and it is possible to know the content.

As described above, the transparent thin film produced by the present invention has a feature that the visible light transmittance in a short wavelength region is high, but in addition to this, under a low pressure of 0.5 Pa or less. By forming the film, the density of the thin film is sufficiently high,
It has a large refractive index. In addition, since the film is formed with a large sputtering power of 4 W / cm ² or more, the film forming speed is high, and the productivity of the thin film can be improved.

Since the transparent thin film produced according to the present invention has the above-mentioned features and advantages, an antireflection film, an optical filter, a surface protective film, a gas barrier film, a transparent electrode, a transparent heat ray reflective film, For a transparent electromagnetic wave shielding film, etc., and especially for a transparent thin film made of a metal oxide containing indium oxide as a main component, as a transparent conductive film material, a transparent electrode for a display, a transparent conductive film for a touch panel, a transparent electromagnetic wave shielding film for a display, etc. It can be widely used for various known applications.

[0036]

Next, an embodiment of the present invention will be described in more detail. However, the present invention is not limited only to the following examples. Hereinafter, the unit used for the gas flow rate (SCC
M) is a gas flow rate (Standard) converted to a standard state.
d Cubic Centimeter per Mi
nute).

Example 1 A polyethylene terephthalate (PET) film having a thickness of 125 μm was mounted as a transparent substrate in a batch type magnetron sputtering apparatus. A 15 mm diameter, 6 mm thickness and a composition of In ₂
O ₃ : SnO ₂ = 95% by weight: 5% by weight (hereinafter referred to as ITO
) Was mounted. The magnetic field strength of the target surface was 260T.

After evacuating the vacuum chamber to 5 × 10 ⁻⁴ Pa, water (2
30 ° C. of argon gas passed through 5 ° C.) and 1 SCCM of oxygen gas not passing through the water were introduced, and the pressure of the gas was adjusted to 0. 0 by adjusting the valve of the vacuum pump.
It was set to 2 Pa. At this time, when the partial pressure of oxygen and water in the vacuum chamber was measured using a quadrupole mass spectrometer (“M-066” manufactured by Anelva), the partial pressure of oxygen was 2.9 × 10 ^−3. In Pa, the water pressure was 9.3 × 10 ⁻³ Pa. These values are lower than the calculated partial pressures because the mass spectrometer detector is located outside the chamber, and the actual oxygen and water partial pressure ratios are It is considered to be close to

Thereafter, a DC sputtering power of 5 W / cm ² per target area was applied to the ITO target, and a 100 nm thick I
A TO thin film was formed. The discharge voltage at this time was 372V. Further, a 1 μm-thick ITO thin film was formed on the Si substrate under the same conditions as above using a Si wafer instead of the PET film as the transparent substrate.

Example 2 A magnet was replaced with a stronger magnet, the magnetic field intensity on the target surface was set to 470 T, and argon gas was introduced without passing water in a tank installed outside the apparatus. In the same manner as in Example 1, an ITO thin film was formed on a PET film as a transparent substrate and further on a Si wafer. The discharge voltage at this time was 325V.
In addition, when the gas was introduced, the oxygen partial pressure in the vacuum chamber was 2.7 × 10 ⁻³ Pa, and the water pressure was 7.9 × 10 ⁻⁴ Pa.

COMPARATIVE EXAMPLE 1 A PET film as a transparent substrate and a Si wafer were formed in the same manner as in Example 1 except that argon gas was introduced without passing water in a tank installed outside the apparatus. An ITO thin film was formed. The discharge voltage at this time is 4
27V. When the gas was introduced, the oxygen partial pressure in the vacuum chamber was 2.7 × 10 ⁻³ Pa, and the water pressure was 7.
It was 9 × 10 ⁻⁴ Pa.

COMPARATIVE EXAMPLE 2 Argon gas was introduced without passing water in a tank installed outside the apparatus, and oxygen gas was passed through the above-mentioned water.
An ITO thin film was formed on a PET film as a transparent substrate and further on a Si wafer in the same manner as in Example 1 except that SCCM was introduced. The discharge voltage at this time is 4
It was 10V. When the gas was introduced, the oxygen partial pressure in the vacuum chamber was 2.9 × 10 ⁻³ Pa, and the water pressure was 3.
It was 1 × 10 ⁻⁴ Pa.

Comparative Example 3 The magnet was replaced and the magnetic field intensity on the target surface was changed to 3
In the same manner as in Example 1, except that the temperature was set to 00T and argon gas was introduced without passing water in a tank installed outside the apparatus, an ITO thin film was formed on a PET film as a transparent substrate and further on a Si wafer. Was formed. The discharge voltage at this time was 440V.

REFERENCE EXAMPLE 1 The same procedure as in Comparative Example 1 was repeated except that the valve of the vacuum pump was adjusted and the pressure was set to 1.5 Pa. A film was formed. The discharge voltage at this time was 405V.

For each of the ITO thin films of Examples 1 and 2, Comparative Examples 1 to 3, and Reference Example 1, the content of argon in the thin film and the potential transmittance (wavelength 400
nm, 450 nm) and refractive index. Result is,
As shown in Table 1. FIG. 1 shows potential transmittance spectra of the ITO thin films of Example 1 and Comparative Example 1 as representative data. In the figure, curve-1a is the ITO thin film of Example 1, and curve-1b is the ITO thin film of Comparative Example 1.

<Argon Content> In order to enhance the detection sensitivity, an ITO thin film having a thickness of 1 μm formed on a Si wafer was used. The content of argon implanted in the thin film was measured using a fluorescent X-ray analyzer “RIX 3” manufactured by Rigaku.
000 ”, the X-ray source is Rh, the output is 50 kV, 5
The measurement was performed at 0 mA and the measurement diameter was 20 mm (diameter). Since the detection limit of the fluorescent X-ray was 10 ppm, those which could not be detected were defined as "detection limit".

<Potential Transmittance> The transparent substrate P
100nm thick ITO film formed on ET film
A thin film was used. Otsuka Electronics' multi-photometer “MC”
PD-3000 ", the transmission spectrum T (λ) at 0 ° incidence in the visible light region with a wavelength of 380 to 780 nm.
(%) Was measured. Further, in a state where the back surface of the base was painted black and the back surface reflection was canceled, a reflection spectrum R (λ) (%) in the same visible light region was measured. Using these measured values T (λ) and R (λ), the potential transmittance Tp in which the influence of the wavelength dependence of the reflectance due to interference has been removed is used.
(Λ) is calculated by the following equation: Tp (λ) (%) = ｛T (λ) / [100−R
(Λ)]｝ × 100 (%).

<Refractive Index> An ITO thin film having a thickness of 100 nm formed on a PET film as a transparent substrate was used. Spectroscopic ellipsometer “M-220” manufactured by JASCO Corporation
Was used to measure the refractive index at a wavelength of 550 nm.

[0049]

As is clear from the results shown in Table 1 and FIG. 1, the ITO thin films of Examples 1 and 2 in which the content of argon implanted into the films was as small as 0.05 atomic% or less were shorter in the short wavelength region of visible light. It can be seen that the transmittance was high and the transparency was excellent. On the other hand, the ITO thin film of Comparative Example 1 having a very high argon content has a low transmittance,
It had a slightly yellowish tint.

Further, although the content of argon in the ITO thin films of Comparative Examples 2 and 3 was smaller than that of the ITO thin film of Comparative Example 1, it was not reduced to 0.05 atomic% or less. No remarkable effect of improving the transmittance is observed.

Further, in the ITO thin film of Reference Example 1 formed by increasing the pressure at the time of sputtering, the mean free path of the recoil particles was reduced, and the content of argon injected into the film was determined by X-ray fluorescence analysis. Although it is below the detection limit, the mean free path of the ITO constituent atoms to be sputtered is also reduced, so that the density of the film is reduced, the film becomes porous, and the refractive index is greatly reduced.

[0053]

As described above, in the present invention, when producing a transparent thin film by the sputtering method, the constituent atoms of the sputtering gas (for example, argon which is a constituent atom of the argon gas) contained in the thin film are reduced to zero. .
By performing the sputtering so as to be 0.05 atomic% or less, the visible light transmittance, in particular, the wavelength 40
It is possible to produce a transparent thin film having a high visible light transmittance in a short wavelength range of 0 to 450 nm, a small amount of yellowing, and a clear color.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram showing potential transmittance spectra of transparent thin films (ITO thin films) of Example 1 and Comparative Example 1.

[Explanation of symbols]

 1a Transparent thin film of Example 1 1b Transparent thin film of Comparative example 1

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H01B 5/14 H01B 13/00 503B 5G323 13/00 503 G02B 1/10 Z (72) Inventor Zenichi Ueda Ibaraki, Osaka 1-1-2 Shimohozumi, Nitto Denko Corporation (72) Inventor Yoshihiro Hieda 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation (72) Inventor Kazuhiko Miyauchi Shimokawa, Ibaraki City, Osaka Prefecture 1-2-1, Hozumi, Nitto Denko Corporation (72) Inventor Yukiko Azumi 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation F-term (reference) 2H048 GA04 GA09 GA18 GA60 2K009 BB11 BB24 CC02 CC03 CC06 DD04 EE03 4F100 AA09A AA12A AA17A AA33A AK01B AK42 BA02 EH66 EH662 GB41 JN01A JN01B 4K029 AA06 AA25 AA25 BA43 BA44 BA45 BA46 BA47 BA48 BA51 BA58 BC08 CA05 EA03 EA09 5G307 FA01 FA02 FB09 FB09

Claims (7)

[Claims] 1. A method for producing a transparent thin film, comprising: producing a transparent thin film by a sputtering method, wherein sputtering is performed such that the constituent atoms of a sputtering gas contained in the thin film are 0.05 atomic% or less. Method. 2. The method according to claim 1, wherein the sputtering gas is an argon gas, and its constituent atoms are argon. 3. The method according to claim 1, wherein the transparent thin film is made of a metal oxide, a metal sulfide, a metal nitride, or a metal halide. 4. The method for producing a transparent thin film according to claim 1, wherein the transparent thin film is made of a metal oxide containing indium oxide as a main component. 5. A sputtering target containing 0.5 P
a, a sputtering voltage of 4 W / cm ² or more per target area is applied under a pressure of not more than
By performing sputtering while keeping the voltage at 00 V or lower, the content of the constituent atoms of the sputtering gas becomes 0.05%.
The method for producing a transparent thin film according to any one of claims 1 to 4, wherein the transparent thin film is produced at not more than atomic%. 6. The method for producing a transparent thin film according to claim 1, wherein a plastic film is used as the transparent substrate, and a transparent thin film is produced thereon. 7. A transparent thin film wherein the content of constituent atoms of the sputtering gas produced by the method according to claim 1 is 0.05 atomic% or less.