JP2007302909A - Thin film and electrode made of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film having high transparency and a low refractive index, and to provide an electrode made of the same. <P>SOLUTION: The thin film comprises the oxide of one or more kinds of metals selected from indium, tin and zinc, and an alkali metal as essential components. The atomic ratio of the alkali metal to all the metals, (the alkali metal atoms)/(the metal atoms+the alkali metal atoms) is 1 to 60 atomic%, and the average reflectivity in the visible region of 400 to 700 nm is 1.5 to 2.0. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin film and an electrode comprising the same. The present invention relates to a transparent thin film electrode used particularly for an electronic device.

  Conventionally, electrode thin films have been applied to liquid crystal display elements, solar cells, touch panels and the like.

  The electrode thin film can be produced by a method such as vacuum deposition, ion plating, laser ablation, sputtering, or other physical vapor deposition, or chemical vapor deposition (CVD) on the substrate. A forming method is known. Among these methods, the sputtering method is the most widely used method for manufacturing liquid crystal display electrodes because it is relatively easy to increase the area and has high productivity.

By the way, the characteristics required for the electrode thin film differ depending on the application. For example, for electrical characteristics, a material having a lower resistance has been required in the past. However, the transparent electrode used on the thin film transistor (TFT) array side only needs to have conductivity for one pixel. Even about 10 ⁻² Ω · cm is sufficient. Rather, it is important that precision processing is possible and there are few etching residues, and indium zinc oxide (IZO) or the like of an amorphous transparent electrode is used. On the other hand, the transparent electrode on the liquid crystal color filter side preferably has a smaller resistance, and indium tin oxide (ITO), which is a typical transparent electrode, is used. In addition, a transparent conductive film in a resistive film type touch panel, in particular, an analog type touch panel, is a system that senses the pressed position by a potential difference, and a 10 ^-1 Ω · cm to 10 ^-3 Ω · cm type is easy to use. . In order to obtain this level of conductivity, methods for adding an insulating oxide such as SiO ₂ or Al ₂ O ₃ to a transparent conductive film such as ITO or IZO have been studied.
As described above, the material of the transparent electrode has been used in which the second and third elements are added depending on the application, centering on indium oxide.

On the other hand, there has not been much study to increase transparency, because the transmittance of the transparent electrode is largely determined only by the refractive index, which is a physical property specific to the material, and there are few factors to consider. is there. If an insulator, CaF and or alkali metal salts of MgF ₂ or the like, silica airgel (Patent Document 1), a method of reducing the density of the apparent making the gap small (Patent Document 2) are known However, there are almost no reported examples of materials having conductivity. Therefore, in order to improve transparency, it is common to use optical design.
For example, ITO having a refractive index of 2.0 is laminated on a glass having a refractive index of 1.5, and the film thickness is designed so that the transmittance at the wavelength (λ) to prevent reflection is maximized (d = λ / 4). By doing so, a transmittance of 90% can be achieved. However, using only the interference effect has a theoretical limit to increasing the transmittance, and the realization of a transparent electrode with a low refractive index has been eagerly desired.
JP 2005-274741 A JP 2005-249982 A

  An object of the present invention is to provide a thin film having high transparency and a low refractive index.

As a result of intensive studies in order to solve the above problems, the present inventors have as a main component an oxide of at least one metal selected from indium, tin, and zinc and an alkali metal as elements constituting the transparent electrode. It has been found that if the thin film is used, the film has a conductivity lower than that of ITO but also has conductivity.
According to the present invention, the following thin films and the like are provided.
1. The main component is an oxide of one or more metals selected from indium, tin, and zinc and an alkali metal,
The atomic ratio of the alkali metal to all metals (alkali metal atom) / (metal atom + alkali metal atom) is 1 to 60 atomic%,
A thin film having an average refractive index of 1.5 to 2.0 in the visible region of 400 nm to 700 nm.
2. 2. The thin film according to 1, wherein an atomic ratio of the alkali metal to all metals is 10 to 55 atomic%.
3. The thin film according to 1 or 2, wherein an atomic ratio of the alkali metal to all metals is 20 to 50 atomic%.
4). The thin film in any one of 1-3 whose average light transmittance of the said visible region is 50% or more.
The electrode which consists of a thin film in any one of 5.1-4.
6). 6. The electrode according to ^{5, wherein the} specific resistance is 10 ⁻⁴ to 10 ⁵ Ω · cm.

  According to the present invention, a thin film having high transparency and a low refractive index can be provided.

The thin film of the present invention is mainly composed of an oxide of one or more metals selected from indium, tin, and zinc and an alkali metal.
The metal contained in the thin film of the present invention is preferably indium and zinc, indium and tin, tin, indium, zinc and tin, and more preferably indium and zinc, indium, tin and tin.
The alkali metal contained in the thin film of the present invention is sodium, potassium, cesium, or lithium, and more preferably sodium, potassium, or cesium.

In the thin film of the present invention, the atomic ratio represented by (alkali metal atom) / (metal atom + alkali metal atom) is 1 to 60 atomic%.
When the atomic ratio is less than 1 atomic%, the effect of reducing the refractive index is reduced, and a reduction in reflectance cannot be expected. On the other hand, when the atomic ratio exceeds 60 atomic%, it is difficult to maintain conductivity, and the structure of the laminated structure of the antireflection film and the conductive film, which is a conventional technique, is not changed.
The atomic ratio is preferably 10 to 55 atomic%, more preferably 20 to 50 atomic%.

Furthermore, the thin film of the present invention has an average refractive index in the visible region (400 to 700 nm) of 1.5 to 2.0. If the average refractive index is less than 1.5, the refractive index of the substrate that is normally in contact with the average refractive index is too small, and the reflection at the interface may increase. If the average refractive index exceeds 2.0, the refractive index of the substrate that is normally in contact with the average refractive index is too high, and the reflection at the interface may increase.
The average refractive index is preferably 1.6 to 1.8.

The thin film of the present invention preferably has an average transmittance of light in the visible region of 50% or more. If the average transmittance is less than 50%, it may be unsuitable for use in a touch panel, a liquid crystal display element or the like.
The average transmittance is more preferably 70% or more, and still more preferably 80% or more.

The thin film of the present invention can be suitably used as an electrode.
The electrode of the present invention preferably has a specific resistance of 10 ⁻⁴ to 10 ⁵ Ω · cm. When the specific resistance is less than 10 ⁻⁴ Ω · cm, plasma reflection occurs, which may be unsuitable as a display device. If the specific resistance exceeds 10 ⁵ Ω · cm, the electrode film may not function.
The specific resistance is preferably 10 ⁻⁴ to 10 Ω · cm.

The thin film of the present invention is prepared on a substrate, for example.
There are various types of base materials depending on applications. For example, transparent polymer materials such as polycarbonate resin, polyarylate resin, polyester resin such as polyethylene terephthalate, polyethersulfone resin, amorphous polyolefin resin, polystyrene resin, acrylic resin, soda lime glass, lead glass, borosilicate glass, Examples thereof include film-like materials, sheet-like materials, and plate-like materials made of glass such as alkali-free glass. Further, it may be a thin film transistor or an organic resin film formed on the thin film transistor by a coating method or the like.
The substrate is preferably a transparent substrate.

Furthermore, you may provide a gas barrier layer, a hard-coat layer, an antireflection layer, etc. as needed on the one or both surfaces of a base material.
Specific examples of the gas barrier layer include those made of ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyacrylonitrile, polyvinylidene chloride, polyvinylidene fluoride, and the like.
Specific examples of the hard coat layer include those made of a titanium-based or silica-based hard coat agent, a polymer material such as polymethyl methacrylate, polyphosphazene, or the like.
Specific examples of the antireflection layer include low refractive index polymers such as fluorine-based acrylic polymers, inorganic fluorides such as MgF ₂ and CaF ₂ , TiO ₂ , SiO ₂ , ZnO, Bi ₂ O ₃ , Al ₂ O _3. Inorganic oxides such as these, and those made of a laminate of these.

Various methods can be applied as a method for forming the thin film of the present invention on a substrate, but a sputtering method (in terms of obtaining a thin film excellent in film uniformity and adhesion to the substrate) It is preferable to apply a reactive sputtering method.
As the sputtering target used in the sputtering method, a sintered compact target made of an oxide corresponding to the target thin film composition is preferably used. Here, the “sintered body target made of an oxide corresponding to the composition of the target thin film” means a sintered body target made of an oxide having a composition capable of obtaining a thin film having the target composition. The composition of the sintered body target is appropriately selected according to the sputtering rate and the composition of the target electrode thin film.

For example, the sintered body target is prepared by mixing a predetermined amount of an oxide or a compound that becomes an oxide by firing with respect to each element other than oxygen (O) among elements constituting the target thin film. The mixture can be obtained by calcining after calcination, and thereafter molding and sintering.
For example, when the target thin film has indium (In), potassium (K), and oxygen (O) as constituent elements, the target sintered compact target can be obtained as follows. .

First, indium oxide or a compound that becomes indium oxide by firing (for example, indium chloride, indium nitrate, indium acetate, indium hydroxide, indium alkoxide, etc.) and a compound that becomes potassium oxide by firing (for example, potassium chloride, potassium nitrate, potassium sulfate, etc.) Are weighed and mixed in predetermined amounts. Next, the obtained mixture is calcined at 500 to 1200 ° C., and the calcined product is pulverized with a ball mill, a roll mill, a pearl mill, a jet mill, or the like, so that the particle diameter is in a range of 0.01 to 1.0 μm and particles. A powder with a uniform diameter is obtained.
Prior to pulverization of the calcined product, the calcined product may be subjected to a reduction treatment at 100 to 800 ° C. If necessary, the powder may be further calcined and pulverized a desired number of times.

Thereafter, the obtained powder is pressure-molded into a desired shape, and the molded product is sintered at 800 to 1700 ° C. At this time, if necessary, polyvinyl alcohol, methyl cellulose, polywax, oleic acid, or the like may be used as a sintering aid.
Thus, the target sintered compact target can be obtained by obtaining a sintered compact.

  Sputtering using the sintered body target described above can be performed by RF sputtering, DC sputtering, or the like. However, from the viewpoint of productivity and film properties of the obtained oxide, DC sputtering is generally used industrially. preferable. An example of the sputtering conditions for DC sputtering is as follows.

That is, the sputtering atmosphere is an inert gas such as argon gas, or a mixed gas of an inert gas and oxygen gas, and the atmospheric pressure (sputtering pressure) during sputtering is about 1 × 10 ⁻² Pa to 5 Pa, and the target applied voltage ( The discharge voltage is less than 1000V.
If the atmospheric pressure during sputtering (sputtering pressure) is less than 1 × 10 ⁻² Pa, the stability of the plasma may be deteriorated, and if it exceeds 5 Pa, the adhesion of the resulting oxide to the substrate may be deteriorated. .
In addition, when the target applied voltage (discharge voltage) is 1000 V or more, the oxide thin film is damaged by the plasma, and the oxide thin film having the desired electrical characteristics cannot be obtained or the target breaks easily. There is a fear.
A preferable value of the target applied voltage (discharge voltage) is less than 800V, more preferably less than 500V.
In order to obtain a high-quality oxide thin film, it is preferable to make the target applied voltage (discharge voltage) as low as possible. However, when it is extremely low, a problem of productivity arises. Therefore, the optimum value of the target applied voltage (discharge voltage) is appropriately selected in consideration of the required thin film quality and productivity. Further, the substrate temperature during film formation (temperature of the transparent base material) is appropriately selected within a temperature range in which the transparent substrate is not deformed or altered by heat according to the heat resistance of the transparent substrate.

The preferable resistance value (bulk specific resistance) of the electrode comprising the thin film thus obtained is appropriately selected according to the application. For example, if only an antistatic function is desired, 10 ⁵ Ω · cm is sufficient. Moreover, if it is for analog type touch panels, 10 ^<-2 > ^{-10 < -3} > (omega | ohm) * cm is easy to use as mentioned above. In addition, although it can be used as an electrode for a liquid crystal display or the like, an appropriate resistance value varies depending on the panel area, the driving method (active or passive), and the TFT side or the counter electrode side.

  The electrode of the present invention can be applied to any device, and can be used for, for example, a liquid crystal display, a touch panel and the like. Even if the resistance is high, malfunction can be prevented by using it as an antistatic function.

Example 1
(1) Production of target 260 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm), 40 g of zinc oxide powder with a purity of 99.99% (average particle size 1 μm), sodium sulfate with a purity of 99.99% (average) 30 g of a particle size of 1 μm was put in a polyimide pot together with ethanol and alumina balls, and mixed for 2 hours in a planetary ball mill. The obtained mixed powder was put into a mold, and preformed at a pressure of 100 kg / cm ^{2 with} a mold press molding machine. Next, after consolidation by a cold isostatic press molding machine at a pressure of 4 t / cm ² , sintering was performed in an air atmosphere at 900 ° C. for 4 hours in a sintering furnace. When the composition of the obtained sintered body was analyzed by ICP analysis, the atomic ratio was In: Zn: Na = 72: 16: 12. The sintered body density was 80%.

(2) Formation of transparent electrode thin film Next, this target was loaded into a sputtering apparatus, and after deaeration to 2 × 10 ⁻⁴ Pa, sputtering pressure was 0.1 Pa, argon: oxygen = 98: 2, sputter output was 0. Film formation was performed on glass under conditions of 1 W / cm ² and a sputtering time of 5 minutes.
When the film thickness and refractive index of the transparent electrode thin film thus obtained were measured with FILMTEK manufactured by Yarman Co., Ltd., the film pressure was 120 nm and the refractive index was 1.8 (average refractive index at a wavelength of 400 to 700 nm). Met. The surface resistance was measured with Loresta FP (manufactured by Mitsubishi Yuka Co., Ltd.), and the specific resistance was calculated from the film thickness, and was 0.005Ω · cm. Further, the composition of this thin film was measured by ICP analysis, and the atomic ratio was In: Zn: Na = 75: 20: 5. And when the average transmittance | permeability of wavelength 400-700nm of this laminated body with a transparent electrode thin film was measured by Shimadzu Corporation UV-3100, it was 92%.

Example 2
As raw materials, 260 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm), 40 g of zinc oxide powder with a purity of 99.99% (average particle size 1 μm), cesium carbonate powder with a purity of 99.99% (average particle size) A target was prepared in the same manner as in Example 1 except that 30 g of 1 μm) was used and the sintering temperature was set to 700 ° C., and a transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Example 3
As raw materials, indium oxide powder having a purity of 99.99% (average particle size 1 μm), 160 g of tin oxide powder having a purity of 99.99% (average particle size 1 μm), and sodium sulfate powder having a purity of 99.99% (average particle size) 1 μm) A target was prepared in the same manner as in Example 1 except that 300 g was used, and a transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Example 4
As raw materials, 190 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm), 45 g of tin oxide powder with a purity of 99.99% (average particle size 1 μm), cesium sulfate powder with a purity of 99.99% (average particle size) 1 μm) A target was prepared in the same manner as in Example 1 except that 200 g was used, and a transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Example 5
As raw materials, 150 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm), 80 g of tin oxide powder with a purity of 99.99% (average particle size 1 μm), potassium sulfate powder with a purity of 99.99% (average particle size) 1 μm) A target was prepared in the same manner as in Example 1 except that 20 g was used, and a transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Examples 6 and 7
A transparent electrode thin film was formed in the same manner as in Example 4 except that the amount of indium oxide, tin oxide and cesium sulfate used was changed and a sputtering target having the composition shown in Table 1 was produced. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Example 8
A target was prepared in the same manner as in Example 1 except that 380 g of tin oxide powder with a purity of 99.99% (average particle size 1 μm) and 60 g of cesium carbonate powder with a purity of 99.99% (average particle size 1 μm) were used as raw materials. Then, a transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Comparative Example 1
(1) Manufacture of target 260 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm) and 40 g of zinc oxide powder with a purity of 99.99% (average particle size 1 μm) are placed in a polyimide pot together with ethanol and alumina balls. And mixed for 2 hours on a planetary ball mill. The obtained mixed powder was put into a mold, and preformed at a pressure of 100 kg / cm ^{2 with} a mold press molding machine. Next, after consolidation by a cold isostatic press molding machine at a pressure of 4 t / cm ² , sintering was performed in an air atmosphere at 900 ° C. for 4 hours in a sintering furnace. When the composition of the obtained sintered body was analyzed by ICP analysis, the atomic ratio was In: Zn = 88: 12. The sintered body density was 80%.

(2) Formation of transparent electrode thin film A transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

Comparative Example 2
A target was produced in exactly the same manner as in Comparative Example 1 except that tin oxide was used instead of zinc oxide. Further, in the same manner as in Comparative Example 1, a transparent electrode thin film was formed, and the film thickness, refractive index, specific resistance, atomic ratio, and transmittance were evaluated.

Comparative Example 3
A target was produced in exactly the same manner as in Comparative Example 1 except that the sintering temperature was 1400 ° C. In this case, the sintered density was 95%. Further, in the same manner as in Comparative Example 1, a transparent electrode thin film was formed, and the film thickness, refractive index, specific resistance, atomic ratio, and transmittance were evaluated.

Comparative Example 4
A target was manufactured in exactly the same manner as in Comparative Example 1. Further, in the same manner as in Comparative Example 1, after forming a transparent electrode thin film and annealing in air at 250 ° C. for 2 hours, the film thickness, refractive index, specific resistance, atomic ratio, and transmittance were evaluated. .

Comparative Example 5
As raw materials, 270 g of indium oxide powder with a purity of 99.99% (average particle size 1 μm), 50 g of zinc oxide powder with a purity of 99.99% (average particle size 1 μm), cesium carbonate powder with a purity of 99.99% (average particle size) A target was prepared in the same manner as in Example 1 except that 10 g of 1 μm) was used and the sintering temperature was set to 700 ° C. A transparent electrode thin film was formed in the same manner as in Example 1. The film thickness, refractive index, specific resistance, atomic ratio, and transmittance of this transparent electrode thin film were evaluated by the same measuring apparatus and measuring method as in Example 1. The results are shown in Table 1.

[Manufacture of color filters]
As an application example of the low refractive index electrode of the present invention, a color filter with a transparent conductive film for driving a liquid crystal was prototyped.

Example 9
(1) Formation of colored layer An ITO film having a surface resistance of 20Ω / □ is formed on a glass substrate as an electrically insulating transparent substrate (manufactured by Geomatic Co., Ltd., glass plate is a surface-polished blue plate glass (silica dip product)) Was prepared, and a colored layer was formed by the micellar electrolysis method in the following manner (a) to (d).

(A) Formation of ITO electrode for electrolysis by photolithography method An ultraviolet curable resist agent (FH22130 manufactured by Fuji Hunt Electronics Technology) was spin-coated on the ITO film at a rotation speed of 1000 rpm. After spin coating, prebaking was performed at 80 ° C. for 15 minutes. Thereafter, the ITO-glass substrate on which the resist film was formed was set in an exposure machine. The mask had a line width of 90 μm, a gap of 20 μm, a line length of 230 mm, and a 1920 stripe vertical pattern. A 2 kW high pressure mercury lamp was used as the light source. A proximity gap of 70 μm was taken, the resist film was exposed to 120 mJ / cm ² , and then developed with a developer (FHD-5 manufactured by Fuji Hunt Electronics Technology), and the resist film was patterned into a predetermined shape. After the development, it was rinsed with pure water, and post-baked at 180 ° C. after rinsing. Next, 1M FeCl ₃ .6NHCl.0.1NHNO ₃ .0.1NCe (NO ₃ ) ₄ aqueous solution is prepared as an etchant, and the resist film patterned in a predetermined shape is used as a mask, The ITO film was etched for about 20 minutes. The end point of etching was measured by electric resistance. After completion of the etching, the substrate was rinsed with pure water, and after rinsing, the resist film was peeled off with 1N NaOH. Thus, striped ITO electrodes for electrolysis were formed on the glass substrate (hereinafter, the glass substrate provided with the ITO electrodes for electrolysis is referred to as an ITO patterning glass substrate).

(B) Formation of light shielding layer Color resist CK, CR, CG and CB manufactured by Fuji Hunt Electronics Technology Co., Ltd. are mixed at a ratio (weight ratio) of 3: 1: 1: 1 as a light shielding layer forming resist agent. What was done was used. The ITO patterning glass substrate produced in the manner of (a) was rotated at 10 rpm, and 30 cc of the resist agent for forming the light shielding layer was sprayed thereon. Next, a uniform resist film was formed on the substrate at a spin coating speed of 500 rpm. After spin coating, prebaking was performed at 80 ° C. for 15 minutes. Thereafter, the resist film was exposed using a mask having a predetermined design (90 × 310 mm square−20 μm line width) while performing predetermined alignment using an exposure machine having an alignment function. A 2 kW high pressure mercury lamp was used as the light source. After taking a proximity gap of 70 μm and exposing the resist film to 100 mJ / cm ² , the resist film was developed with a developer (Fuji Hunt CD manufactured by Fuji Hunt Electronics Technology Co., Ltd. diluted four times with pure water) for 30 seconds. The resist film was patterned into a predetermined shape. After development, it was rinsed with pure water, and after rinsing, post-baked at 200 ° C. for 100 minutes. In this way, a light-shielding layer having a predetermined shape made of the resist film was obtained (hereinafter, the layer formed up to the light-shielding layer is referred to as a glass substrate with a light-shielding layer).

(C) Preparation of dispersion for micelle electrolysis As a dispersion for forming a colored layer (hereinafter referred to as R colored layer) having a high spectral transmittance in the red wavelength region, dispersion of chromoftal red A2B (manufactured by Ciba Geigy) is used. A liquid (dispersion medium; pure water) was used. Further, a dispersion for forming a colored layer (hereinafter referred to as a G colored layer) having a high spectral transmittance in the green wavelength region is a dispersion (dispersion medium; pure water) of heliogen green L9361 (manufactured by BASF) and irgadine. A dispersion (dispersion medium: pure water) of Yellow 2 RLT (manufactured by Ciba Geigy) was mixed at a ratio of 70:30 (weight ratio) while being kept at 20 ° C., and the mixture was further mixed with an ultrasonic homogenizer for 30 minutes. It was prepared by dispersing. As a dispersion liquid for forming a colored layer (hereinafter referred to as B colored layer) having a high spectral transmittance in the blue wavelength region, a dispersion liquid (dispersion medium: pure water) of Fastgen Blue TGR (manufactured by Dainippon Ink Co., Ltd.) And Fastgen Super Violet 2RN (Dainippon Ink Co., Ltd.) were mixed at a ratio of 80:20 (weight ratio) while being kept at 20 ° C.

(D) Micellar electrolysis First, a dispersion for forming an R colored layer (liquid temperature 20 ° C.) prepared by the procedure of (c) above using the glass substrate with a light shielding layer prepared by the procedures of (a) and (b) above. Then, a potentiostat was connected to the electrolysis ITO electrode at the location where the R colored layer was to be formed. And 0.5Vvs. SCE and constant potential electrolysis for 25 minutes were performed to obtain an R colored layer. After electrolysis, it was rinsed with pure water, and after rinsing, it was baked at 100 ° C. for 15 minutes.
Next, this substrate is immersed in a dispersion liquid for forming a G colored layer (liquid temperature 20 ° C.) prepared as described in (c) above, and a potentiostat is applied to the electrolysis ITO electrode where the G colored layer is to be formed. Connected. And 0.5Vvs. SCE and constant potential electrolysis for 20 minutes were performed to obtain a G colored layer. After electrolysis, it was rinsed with pure water, and after rinsing, it was baked at 100 ° C. for 15 minutes.
Finally, this substrate is immersed in a dispersion liquid for forming a B colored layer (liquid temperature 20 ° C.) prepared as described in (c) above, and a potentiostat is applied to the electrolysis ITO electrode where the B colored layer is to be formed. Connected. And 0.5Vvs. SCE and constant potential electrolysis for 15 minutes were performed to obtain a B colored layer. After electrolysis, it was rinsed with pure water, and after rinsing, it was baked at 100 ° C. for 15 minutes.
In this way, the R colored layer, the G colored layer, and the B colored layer were alternately formed in a stripe shape on the glass substrate with the light shielding layer (hereinafter, the glass substrate provided with the R colored layer, the G colored layer, and the B colored layer is a colored layer). Called glass substrate).

(2) Formation of transparent protective layer The glass substrate with a colored layer obtained in (1) above is set on a spin coater, and a polysiloxane resin (OS-808 manufactured by Nagase Sangyo Co., Ltd.) as a material for the transparent protective film is used. It apply | coated on the colored layer using the dispenser. At this time, the resin was uniformly applied to the entire surface of the glass substrate with a colored layer by slowly rotating the substrate at 10 rpm. Furthermore, the glass substrate with the colored layer was rotated at 800 rpm for 1 minute to obtain a uniform resin thin film. Thereafter, the resin was cured by baking at 260 ° C. for 2 hours. Thereby, the target transparent protective layer was obtained.

(3) Formation of transparent electrode for driving liquid crystal A glass substrate with a colored layer provided with a transparent protective layer is attached to a DC magnetron direct sputtering apparatus, and the inside of the vacuum chamber is depressurized to 1 × 10 ⁻⁶ Torr or less, and the purity is 99.99. % Argon gas was introduced up to 3 × 10 ⁻³ Torr. And the sputtering target manufactured in Example 2 was used, and sputtering was performed under the conditions of a target applied voltage of 420 V and a substrate temperature of 200 ° C. By this sputtering, a transparent electrode for driving a liquid crystal having a thickness of about 0.12 μm was formed on the transparent protective layer. Thereby, the target color filter for liquid crystal displays was obtained.

The surface resistance of the color filter for liquid crystal display thus obtained (surface resistance of the transparent electrode for liquid crystal driving) was 1000Ω / □. When the transmittance of this color filter was measured, 75% was obtained in the red (610 nm) region, 80% in the green (540 nm) region, and 75% in the blue (460 nm) region.
This color filter is suitable as a color filter for a thin film transistor type active matrix liquid crystal display.

Comparative Example 6
For comparison, the IZO target used in Comparative Example 1 was used as a liquid crystal driving transparent electrode, and a color filter with a transparent electrode was produced in exactly the same manner as in Example 7. When the transmittance of this color filter was measured, it decreased by about 2 to 3%, 72% in the red (610 nm) region, 77% in the green (540 nm) region, and 72% in the blue (460 nm) region.
There are many methods for producing a color filter, such as a printing method and a pigment dispersion method, and the method is not limited to the above production method.

[Manufacture of touch panels]
Example 10
(1) Preparation of transparent electrode substrate A long biaxially stretched polyethylene terephthalate film (size: 300 mm × 10 m, thickness 125 μm, hereinafter referred to as a PET roll) is used as a transparent base material, and a sputtering target is described in Example 4. Using the same composition as described above, a film was formed in the following manner. The atomic composition ratio of the oxide thin film was determined by induction plasma emission spectroscopy (ICP).
First, a PET roll was attached to a continuous traveling DC magnetron sputtering apparatus, and the inside of the vacuum chamber was depressurized to 5 × 10 ⁻³ Pa or less. Next, argon gas (purity 99.99%) was introduced so that the pressure in the vacuum chamber was 2 × 10 ⁻¹ Pa, the sputtering output was 1.6 W / cm ² (target applied voltage was 400 V), and the substrate Pre-sputtering was performed at a temperature set to 20 ° C. After pre-sputtering, while maintaining the sputtering output and the substrate temperature at the above values, a mixed gas of argon gas and oxygen gas (volume ratio of argon gas to oxygen gas = 97: 3) is set to a vacuum chamber pressure of 2 × 10. ^-1 Pa was introduced, and an oxide thin film (transparent electrode film) was formed on one side of the PET roll at a running speed of 100 cm / min.
A transparent electrode substrate was obtained by cutting out a PET film with an oxide thin film having a size in plan view of 16 × 16 cm from the PET roll with a transparent electrode film obtained as described above.
About each of the obtained transparent electrode substrate, the film thickness of the transparent electrode film which comprises the said transparent electrode substrate, surface resistance, the standard deviation of surface resistance, and specific resistance were calculated | required. Further, when the transmittance of light with a wavelength of 550 nm was determined for this transparent electrode substrate, it was 93%.

(2) Production of touch panel Using two PET films with an oxide thin film (transparent electrode film) of 16 × 16 cm in plan view obtained in (1) above, the analog touch panel shown in FIG. It was produced as follows.
First, silver paste (manufactured by Fujikura Kasei Co., Ltd.) is formed on a pair of edge portions facing each other in the transparent electrode film 12 constituting one transparent substrate 10, with electrode terminals 14 and 16 having a strip shape having a width of 3 mm. D-550), respectively. Similarly, electrode terminals 24 and 26 each having a band shape of 3 mm in width are provided on a pair of edge portions facing each other in the transparent electrode film 22 constituting the other transparent substrate 20. .
Next, in the transparent substrate 10 and the transparent substrate 20, the transparent electrode films 12 and 22 face each other, and the direction connecting the electrode terminals 14 and 16 and the direction connecting the electrode terminals 24 and 26 are orthogonal in plan view. In this way, they were bonded together. At this time, a spherical spacer (not shown) made of SiO _{2 with} a particle diameter of 15 μm was used so that the distance between the transparent electrode films 12 and 22 was 15 μm.
Thereafter, the electrode terminals 14 and 16 provided on the transparent electrode film 12 were connected to the 15 V DC power source V ₁ via lead wires 32 and 34. At this time, the switch S ₁ was interposed in the middle of the lead wire 32, and the switch S ₂ was interposed in the middle of the lead wire 34. Further, electrode terminals 24 and 26 provided on the transparent electrode film 22 were connected to a 15V DC power source V ₂ via lead wires 36 and 38. At this time, in the middle of the lead wire 36 is interposed switch S _3, was in the middle of the lead wire 38 is interposed switch S _4.
Thus, the touch panel 1 was obtained by electrically connecting the electrode terminals 14 and 16 and the DC power source V ₁ and the electrode terminals 24 and 26 and the DC power source V ₂ .
When the touch pen 40 was swept down in the direction of arrow A and the sweep distance and the display of the voltmeter 50 were confirmed, good linearity was obtained.
When the touch panel obtained in this manner was attached to a liquid crystal display, a highly transparent touch panel that did not deteriorate the brightness of the liquid crystal could be obtained.

Comparative Example 7
A touch panel shown in FIG. 1 was produced in the same manner as in Example 10 except that the ITO target used in Comparative Example 4 was used as a target for producing a transparent electrode for a touch panel. The transmittance of the ITO / PET laminate was 88%, which was 5% lower than that of the laminate used in Example 10. This is because the refractive index of ITO is large.
Moreover, although the obtained touch panel was affixed on the liquid crystal display, the reflectance of the touch panel was high compared with Example 10, and the visibility of the liquid crystal display was inferior.

  As described above in detail, the thin film of the present invention can be used in any device that requires a transparent electrode, for example, a liquid crystal display, a touch panel, a solar cell, and the like.

It is the schematic of the analog type touch panel created in Example 7 and Comparative Example 10.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Touch panel 10,20 Transparent substrate 12,22 Transparent electrode film 14,16,24,26 Electrode terminal 32,34,36,38 Lead wire 40 Touch pen 50 Voltmeter

Claims (6)

The main component is an oxide of one or more metals selected from indium, tin, and zinc and an alkali metal,
The atomic ratio of the alkali metal to all metals (alkali metal atom) / (metal atom + alkali metal atom) is 1 to 60 atomic%,
A thin film having an average refractive index of 1.5 to 2.0 in the visible region of 400 nm to 700 nm.   The thin film according to claim 1, wherein an atomic ratio of the alkali metal to all metals is 10 to 55 atomic%.   The thin film of Claim 1 or 2 whose atomic ratio with respect to all the metals of the said alkali metal is 20-50 atomic%.   The thin film as described in any one of Claims 1-3 whose average light transmittance of the said visible region is 50% or more.   The electrode which consists of a thin film as described in any one of Claims 1-4. The electrode according to claim 5, wherein the specific resistance is 10 ⁻⁴ to 10 ⁵ Ω · cm.

Images