JPWO2008044473A1 - Method for forming transparent conductive film and transparent conductive film substrate - Google Patents

Abstract

The present invention provides a method for forming a transparent conductive film and a transparent conductive film substrate containing, as a main component, titanium oxide having excellent transparency and conductivity without being restricted by a base material. The method for forming a transparent conductive film is a method for forming a transparent conductive film, in which a transparent conductive film containing titanium oxide as a main component is formed by plasma CVD treatment on a substrate, and the plasma CVD treatment includes at least A reactive gas containing a titanium compound, a dopant raw material, and a reducing gas is introduced into the discharge space to form a plasma state, and the substrate is exposed to the reactive gas in a plasma state, whereby titanium oxide is mainly formed on the substrate. A thin film as a component is formed.

Description

  The present invention relates to a method for forming a transparent conductive film mainly composed of titanium oxide having excellent light transmittance and conductive performance, and a transparent conductive film substrate.

  Conventionally, an article having a transparent conductive film with low electrical resistance (low specific resistance) and high visible light transmittance, for example, a transparent conductive film is a liquid crystal image display device, organic electroluminescence (hereinafter abbreviated as organic EL). It is used in many fields such as transparent electrodes for flat displays such as image display devices, plasma display panels, and field emission displays, transparent electrodes for solar cells, electronic paper, touch panels, electromagnetic wave shielding materials, and infrared reflective films.

As the transparent conductive film, a metal thin film such as Pt, Au, Ag, or Cu, SnO ₂ , In ₂ O ₃ , CdO, ZnO, SnO ₂ : Sb, SnO ₂ : F, ZnO: Al, In ₂ O ₃ : Sn, etc. There are non-oxides such as a complex oxide film made of an oxide and a dopant, chalcogenide, LaB ₆ , TiN, and TiC.

Among the materials for forming the transparent conductive film, an indium oxide (hereinafter also referred to as ITO) film doped with tin is most widely used because of its excellent electrical characteristics and ease of processing by etching. A transparent conductive film such as ITO has been mainly formed by a wet film formation method typified by coating, or a vacuum film formation method such as a sputtering method, a vacuum deposition method, or an ion plating method. The vacuum evaporation method and the sputtering method can obtain a low-resistance transparent conductive film, and industrially have excellent conductivity with a specific resistance value of the order of 10 ⁻⁴ Ω · cm using a DC magnetron sputtering apparatus. An ITO film can be obtained.

  However, indium, which is the main constituent metal of ITO transparent conductive film, is a rare metal, and with the increase in usage in recent years, there is a risk of depletion in the near future when estimated from the current reserves, replacing ITO Depending on the material, the development of a transparent conductive film having excellent characteristics has become an urgent issue.

In recent years, a method for obtaining high transparency and conductivity close to that of ITO by using a titanium oxide film has been reported (for example, see Non-Patent Documents 1 and 2). In these reported methods, a doped metal is mainly formed on a glass substrate or an aluminum oxide substrate by a reactive RF sputtering method or a pulsed laser deposition method (PLD method) at a substrate temperature of 250 ° C. to 500 ° C. TiO ₂ thin films using niobium as: a method of forming a (Nb TiO ₂ thin film). According to each non-patent document, a thin film formed of TiO ₂ alone has a resistivity of the order of 1 to 10 ⁻¹ Ωcm and is insufficient for a conductive film, but is composed of TiO ₂ doped with niobium. The thin film has a resistivity reduced by 1 to 2 orders, and a transparent conductive film having a low resistivity is obtained. Further, after the thin film is formed, heat treatment (reduction is performed at 250 ° C. to 500 ° C. in a reducing atmosphere. It is reported that the resistivity is further reduced by applying (annealing), and as a technology to replace ITO, TiO ₂ transparent conductive film using niobium as a doped metal can be applied to thin display members, solar cells, etc. Is being discovered.

However, the methods described in the above non-patent documents all use a glass substrate or a metal substrate to form a TiO ₂ -based transparent conductive film under a high temperature environment of 250 ° C. to 500 ° C. It is necessary to form a TiO ₂ -based transparent conductive film and subsequently to perform heat treatment (reduction annealing) at 250 ° C. to 500 ° C. in the same reducing atmosphere. For this reason, for example, when a transparent conductive film is formed as an electrode on a color filter used in a thin display member or the like, the heat resistance of the color material constituting the color filter under a high temperature environment of 250 ° C. to 500 ° C. From the point of view, it becomes difficult to apply.

  Also, in the fields of liquid crystal and organic EL, etc. in the fields of thin display members and solar cells, in recent years, there has been a great demand for light weight, thinning, impact resistance, flexibility, etc. It is moving to a resin substrate. In this case, the heat resistance of the commonly used transparent resin base material is usually 150 ° C. or less, and even if it is a material with higher heat resistance, the upper limit is about 220 ° C. From the applicable processing temperature. Since the base material that can be used is naturally restricted, it is a great obstacle when applied to the above fields.

  As described above, the method currently used for forming a titanium oxide film is mainly a physical vapor deposition method such as a sputtering method, a PLD (pulse laser deposition) method, or an EB (Electron Beam) vapor deposition method. As a result, a heat treatment step in a reducing atmosphere is required. This requires a high temperature of 400 ° C. or higher.

  On the other hand, in the physical vapor deposition method, the solid substance containing the constituent atoms of the target hard film is made into atoms, molecules and clusters by physical action (heating, sputtering effect, etc.), and the space where the substrate is placed In this method, a thin film is formed by supplying to the substrate and further transported to the surface of the substrate.

  On the other hand, the compound thin film produced by the PVD method tends to show a chemical composition ratio deviation, that is, non-stoichiometry. For example, the value of x in the TiOx film produced by sputtering is 2.0 of the stoichiometric composition. In many cases, it is shifted slightly.

In addition, in the process of forming a transparent conductive film using TiO ₂ , it is necessary to precisely control the amount of oxygen deficiency and the amount of dopant introduced in order to create a donor necessary for developing the conductive function. is there. In this regard, in reactive RF sputtering or pulsed laser deposition (PLD), it is necessary to make minute adjustments of the mixing ratio of minute additive gases, targets, and vapor deposition materials, and finally obtained TiO ₂ It is considered extremely difficult to obtain the homogeneity of the system transparent conductive film.
Furubayashi et al. , Appl. Phys. Lett. 86,252101 (2005) 67th Annual Meeting of the Japan Society of Applied Physics, Preliminary Proceedings (Autumn 2006), pages 566 to 567, 30p-RA-12 to 16

  The present invention has been made in view of the above problems, and its object is to form a transparent conductive film mainly composed of titanium oxide that is excellent in transparency and conductivity without being restricted by the base material. A method and a transparent conductive film substrate are provided.

  The above object of the present invention is achieved by the following configurations.

  1. A transparent conductive film forming method for forming a transparent conductive film containing titanium oxide as a main component on a base material by plasma CVD, wherein the plasma CVD process comprises at least a titanium compound, a dopant raw material, and a reducing gas. Forming a thin film mainly composed of titanium oxide on the base material by introducing a reactive gas containing it into a discharge space to form a plasma state and exposing the base material to the reactive gas in a plasma state. A method for forming a transparent conductive film, which is characterized.

  2. 2. The method for forming a transparent conductive film according to 1 above, wherein the plasma CVD process is an atmospheric pressure plasma process for forming a film under an atmospheric pressure or a pressure near atmospheric pressure.

  3. 3. The method for forming a transparent conductive film according to 1 or 2, wherein the reducing gas is hydrogen gas.

  4). 4. The method for forming a transparent conductive film according to any one of 1 to 3, wherein the temperature of the base material during the plasma CVD process is 220 ° C. or lower.

  5. 5. The method for forming a transparent conductive film according to any one of 1 to 4, wherein after the plasma CVD treatment is performed, heat treatment is performed in an atmosphere containing at least hydrogen gas.

  6). 6. The method for forming a transparent conductive film according to any one of 1 to 5, wherein the dopant material is a niobium-containing compound.

  7). 7. The method for forming a transparent conductive film according to any one of 1 to 6, wherein the base material is a transparent resin.

  8). A transparent conductive film substrate in which a silicon oxide layer and a transparent conductive film layer mainly composed of titanium oxide are sequentially laminated on a transparent resin, the transparent conductive film layer mainly composed of titanium oxide, 8. A transparent conductive film substrate formed by the method for forming a transparent conductive film according to any one of 1 to 7.

  9. 9. The transparent conductive film substrate according to 8, wherein the silicon oxide layer is formed by atmospheric pressure plasma treatment.

  According to the present invention, it is possible to provide a method for forming a transparent conductive film and a transparent conductive film substrate that are excellent in transparency and conductivity without being restricted by the base material.

It is the schematic which shows an example of the plasma jet type atmospheric pressure plasma discharge processing apparatus which concerns on this invention. It is the schematic which shows another example of the plasma jet type atmospheric pressure plasma discharge processing apparatus which concerns on this invention. It is the schematic which showed an example of the atmospheric pressure plasma discharge processing apparatus of the 2 frequency jet system useful for this invention. It is the schematic which shows an example of the other 2 frequency system plasma jet type atmospheric pressure plasma discharge processing apparatus which installed the power supply of a different frequency in each electrode. It is the schematic which shows an example of the direct type atmospheric pressure plasma discharge processing apparatus applicable to this invention. It is the schematic which shows an example of the other 2 frequency system direct type atmospheric pressure plasma discharge processing apparatus which installed the power supply of a different frequency in each electrode.

Explanation of symbols

21, 110 Atmospheric pressure plasma discharge treatment device 22, G, G ° gas 23 Mixed gas 31 Power supply 31a, 31b High frequency power supply 41a, 41b Electrode 42 Dielectric 43 Discharge space 46, F substrate 47 Moving stage, Moving stage electrode 101a, 101b High-frequency filter 111 First electrode 112 Second electrode 121 First power supply 122 Second power supply 123 First filter 124 Second filter 126 High-frequency voltage probe 127, 128 Oscilloscope

  Hereinafter, the best mode for carrying out the present invention will be described in detail.

  As a result of intensive studies in view of the above problems, the present inventor is a method for forming a transparent conductive film, which forms a transparent conductive film containing titanium oxide as a main component by plasma CVD treatment on a substrate, A plasma treatment introduces a reactive gas containing at least a titanium compound, a dopant raw material, and a reducing gas into a discharge space to form a plasma state, and exposes the base material to the reactive gas in a plasma state. A thin film mainly composed of titanium oxide is formed on the transparent conductive film, and the transparent conductive film excellent in transparency and conductivity is obtained without being restricted by the substrate. It has been found that a membrane method can be found, and it is up to the present invention.

  That is, in the invention according to claim 1 of the present invention, a reactive gas containing a titanium compound, a dopant raw material, and a reducing gas is formed by plasma CVD without exposing the substrate to an excessively high temperature environment. By forming a film, it is possible to perform a chemical reaction at a molecular level in a low-temperature environment in a dense plasma atmosphere, and as a result, it is possible to form a thin film mainly composed of dense and good-quality titanium oxide, A transparent conductive film excellent in transparency and conductivity could be obtained.

  Furthermore, in the invention according to claim 2 of the present invention, the plasma density at the time of film formation is applied as a plasma CVD process by applying an atmospheric pressure plasma processing method of forming a film under atmospheric pressure or a pressure near atmospheric pressure. And the stress between the formed thin film and the substrate can be lowered, and as a result, the adhesion can be further improved.

  Further, in the invention according to claim 3 of the present invention, by using hydrogen gas as the reducing gas, a reducing gas atmosphere in a plasma state is formed, and in the transparent conductive film mainly composed of titanium oxide to be formed, The transparent electroconductive film which can suppress the oxygen deficiency quantity to an appropriate quantity and has titanium oxide excellent in film homogeneity as a main component was obtained.

  Further, in the invention according to claim 4 of the present invention, film formation in a high temperature environment of 250 ° C. to 500 ° C. is conventionally inappropriate by suppressing the temperature of the base material during plasma CVD processing to 220 ° C. or lower. The transparent resin base material that has been used can be used, and the application field of the transparent conductive film base material can be dramatically expanded.

  In the invention according to claim 5 of the present invention, after the plasma CVD process is performed, a heat treatment is performed in an atmosphere containing at least hydrogen gas, so that the transparent conductive film containing titanium oxide as a main component is formed. The resistance value could be further reduced.

  Further, in the invention according to claim 6 of the present invention, by applying a niobium-containing compound as a dopant raw material, it can be made to function extremely effectively as a dopant, and a low-resistance transparent conductive film can be obtained.

  Further, in the invention according to claim 7 of the present invention, a thin film mainly composed of titanium oxide imparted with weight reduction, thickness reduction, impact resistance, flexibility and the like by using a transparent resin as a base material is provided. Thus, liquid crystal, organic EL, etc. can be applied to fields such as thin display members and solar cells.

  In the invention according to claim 8 of the present invention, a transparent conductive film layer mainly composed of titanium oxide formed on a transparent resin by a method of forming a transparent conductive film according to the present invention and a silicon oxide layer; By sequentially forming the transparent conductive film substrate having laminated layers, it is possible to suppress the diffusion of low molecular resin components and impurity components from the base material to the transparent conductive film layer due to the subbing effect of the silicon oxide layer. As a result, the silicon oxide layer The adhesion between the transparent conductive film layer mainly composed of titanium oxide and the transparent resin as a base material is improved through the use of titanium oxide, and the main component is titanium oxide having excellent stability over time of conductive performance, environmental resistance, and adhesion performance. A transparent conductive film substrate having a transparent conductive film as a component can be obtained. Further, in the invention according to claim 9 of the present invention, it is preferable that the silicon oxide layer is also formed by atmospheric pressure plasma treatment.

  Details of the present invention will be described below.

  The method for forming a transparent conductive film of the present invention includes a plasma CVD treatment method on a base material, wherein a reactive gas containing at least a titanium compound, a dopant raw material and a reducing gas is introduced into a discharge space to form a plasma state, A thin film mainly composed of titanium oxide is formed on the base material by exposing the base material to the reactive gas in a plasma state.

"Base material"
The substrate used in the present invention is not particularly limited as long as it is capable of forming a plate-like, sheet-like or film-like planar shape or a thin film such as a lens or other three-dimensional shape on the surface thereof. Absent. There is no limitation on the form or material of the substrate as long as the substrate is exposed to an excitation gas in a plasma state regardless of whether it is in a stationary state or in a transported state, and a uniform thin film is formed. The shape may be a planar shape or a three-dimensional shape, and examples of the planar shape include a glass plate and a resin film. Various materials such as glass, resin, earthenware, metal, and non-metal can be used. Moreover, from the viewpoint that the transparent conductive film can be formed in a low-temperature environment according to the present invention, and the heat treatment can be performed at a low temperature after the film is formed. It is preferable to use a transparent resin (film) having good permeability and high heat resistance. Examples of the transparent resin (film) include polymethyl methacrylate (PMMA), acrylonitrile-butadiene-styrene resin (ABS), ethylene-vinyl acetate resin (EVAC), ethylene-vinyl alcohol resin (EVOH), polyamide (PA), Polycarbonate (PC), polybutylene terephthalate (PBT), polyethylene (PE), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polymethylpentene (PMP), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), styrene-acrylonitrile resin (SAN), triacetyl cellulose (TAC), cellulose triacetate, cellulose Diacetate, a film made of a resin such as a cellulose ester such as cellulose acetate propionate or cellulose acetate butyrate. Furthermore, during the atmospheric pressure plasma CVD process described later, the transparent resin substrate is polyethylene terephthalate (PET), triacetyl cellulose (TAC), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), acrylic. Use of a resin is preferable from the viewpoint of forming a transparent conductive film mainly composed of titanium oxide, which is rich in permeability, lightweight, and has low resistance.

  Moreover, on the base material which concerns on this invention, an anti-glare layer and a clear hard-coat layer can be coated as needed, and a back-coat layer can be coated.

《Transparent conductive film mainly composed of titanium oxide》
The transparent conductive film mainly composed of titanium oxide according to the present invention is a thin film mainly composed of titanium oxide having a dopant. The transparent conductive film mainly containing titanium oxide according to the present invention mainly containing titanium oxide having a dopant is a transparent conductive film mainly containing titanium oxide, depending on the film forming method and film forming conditions to be applied. The composition is slightly different, and even a titanium oxide layer does not typically have a composition of TiO ₂ as a whole. There is a component such as a trace component (element) taken from a source gas or a dopant according to the present invention. Therefore, the term “mainly composed of titanium oxide” as used in the present invention means a film having at least 90% of a TiO ₂ region as a composition. It is.

(Formation of transparent conductive film mainly composed of titanium oxide)
In the present invention, as a method for forming a thin film containing titanium oxide as a main component on the above-mentioned substrate, plasma CVD treatment is applied. Among them, a vacuum facility is not required, and the temperature is low. It is preferable to apply an atmospheric pressure plasma treatment method capable of continuously or semi-continuously forming a film base or substrate under conditions. Note that details of an atmospheric pressure plasma treatment method (also referred to as an atmospheric pressure plasma CVD method) applicable to the present invention will be described later.

  In the formation of the transparent conductive film mainly composed of titanium oxide according to the present invention by applying the plasma CVD method, a reactive gas containing a titanium compound, a dopant raw material and a reducing gas is introduced into the discharge space to form a plasma state. By exposing the substrate to a reactive gas in a plasma state, a thin film mainly composed of titanium oxide is formed on the substrate. A reactive gas, which is a forming gas of a transparent conductive film mainly composed of titanium oxide, receives energy from the discharge gas in a discharge space to be in an excited state or a plasma state, and forms a transparent conductive film mainly composed of titanium oxide. It is a gas, or a gas that controls the reaction or accelerates the reaction. It is preferable that the reactive gas of the transparent conductive film which has this titanium oxide as a main component is 0.01-10 volume% in all the gas, More preferably, it is 0.1-3 volume%.

(Titanium oxide)
In the present invention, the raw materials used for forming the transparent conductive film mainly composed of titanium oxide according to the present invention include an organic titanium compound, a titanium hydrogen compound, a titanium halide, and the like. Ethoxy titanium, trimethoxy titanium, triisopropoxy titanium, tributoxy titanium, tetraethoxy titanium, tetraisopropoxy titanium, methyl dimethoxy titanium, ethyl triethoxy titanium, methyl triisopropoxy titanium, triethyl titanium, triisopropyl titanium, tributyl titanium, Tetraethyltitanium, tetraisopropyltitanium, tetrabutyltitanium, tetradimethylaminotitanium, dimethyltitanium di (2,4-pentanedionate), ethyltitanium tri (2,4-pentanedionate), titanium tris 2,4-pentanedionate), titanium tris (acetmethyl acetate), triacetoxy titanium, dipropoxypropionyloxy titanium, etc., dibutyryloxy titanium, titanium hydrogen compound as monotitanium hydrogen compound, dititanium hydrogen compound, halogen, etc. Examples of titanium fluoride include trichlorotitanium and tetrachlorotitanium, and any of them can be preferably used in the present invention. Two or more of these thin film forming gases can be mixed and used at the same time. It can also be dissolved in a solvent and used as a solution.

(Dopant raw material)
One feature of the method for forming a transparent conductive film of the present invention is that doped TiO ₂ is used. When the transparent conductive film mainly composed of titanium oxide according to the present invention is formed by applying the atmospheric pressure plasma CVD method, a dopant material is included in the reactive gas. As the dopant material, it is preferable to use a metal element mainly having a periodic table valence different from the Ti element of TiO ₂ , and in particular, V, Nb, Ta, B, Al, Ga, In, Tl. Among these, Nb, Ta, V, and the like are preferably used from the viewpoint of forming a low-resistance transparent conductive film that is an object effect of the present invention. By including niobium in titanium oxide, niobium functions as a dopant in the transparent conductive film containing titanium oxide as a main component, carriers (electrons) are generated, and conductivity (resistance performance) can be improved. .

  In the method for forming a transparent conductive film of the present invention, it is preferable to apply a niobium-containing compound as a useful dope raw material, such as an organic niobium compound, a niobium hydroxide compound, a niobium halide, and the like. For example, pentaethoxyniobium, penta-n-butoxyniobium, penta-n-butoxyniobium, niobium phenoxide, tetrakis (2,2,6,6-tetramethyl-3,5-heptanedionato) niobium, niobium hydroxide As the compound, niobium hydroxide, niobium halide, niobium trichloride oxide, niobium chloride and the like can be used.

  The amount of the reactive gas contained in the reactive gas is such that the amount of dopant in the thin film mainly composed of titanium oxide is in the range of 1% by mass to 20% by mass, preferably in the range of 5% by mass to 10% by mass. It is preferable to adjust the ratio of the dopant compound in the gas.

(Conditions for forming a transparent conductive film mainly composed of titanium oxide)
In the present invention, when a transparent conductive film mainly composed of titanium oxide is formed on a base material using a plasma CVD method, the reactive gas for the transparent conductive film mainly composed of titanium oxide is used as the reactive gas for the transparent conductive film mainly composed of titanium oxide. The transparent conductive film mainly composed of titanium oxide formed by containing a reducing gas selected from hydrogen gas, hydrocarbons such as methane, and water as the reducing gas can be formed into a more uniform and dense film. From the viewpoint of improving conductivity, adhesion, and crack resistance, hydrogen gas is more preferable. The reducing gas is preferably 0.0001 to 10% by volume, more preferably 0.001 to 5% by volume with respect to 100% by volume of the total gas.

  The transparent conductive film mainly composed of titanium oxide according to the present invention can be formed by exposing the discharge gas and the oxidizing gas to a gas excited to a plasma state. Examples of the sex gas include oxygen, ozone, hydrogen peroxide, and carbon dioxide. Examples of the discharge gas at this time include a gas selected from helium, argon, and nitrogen. The concentration of the oxidizing gas component in the mixed gas composed of the oxidizing gas and the discharge gas is preferably 0.0001 to 30% by volume, more preferably 0.001 to 15% by volume, particularly 0.01 to 10% by volume. It is preferable to make it. The optimum value of each concentration of the oxidizing gas species and the discharge gas selected from helium, argon, and nitrogen can be appropriately selected depending on the substrate temperature, the number of oxidation treatments, and the treatment time. As the oxidizing gas, oxygen and carbon dioxide are preferable, and a mixed gas of oxygen and argon is more preferable. Further, in order to control the discharge region, several percent to several tens percent of nitrogen can be mixed.

<Heat treatment of transparent conductive film mainly composed of titanium oxide>
In the method for forming a transparent conductive film of the present invention, after forming a transparent conductive film mainly composed of titanium oxide on a substrate according to the above method, the transparent conductive film mainly composed of titanium oxide is formed. It is preferable to perform a resistance reduction treatment by performing a heat treatment in an atmosphere containing at least hydrogen gas.

  As the heat treatment, heat treatment can be performed at 100 ° C. to 500 ° C. in a reducing atmosphere containing hydrogen gas.

  In the method for forming a transparent conductive film of the present invention, the heat treatment step is an off-line process in which a transparent conductive film containing titanium oxide as a main component is formed on a substrate by an atmospheric pressure plasma processing apparatus, and then heat treatment is performed in an independent form. Even if it is a system, or after forming the transparent conductive film which has titanium oxide as a main component with an atmospheric pressure plasma processing apparatus, you may heat-process continuously by an on-line system.

  In addition, in the method for forming a transparent conductive film of the present invention, the step of forming a transparent conductive film mainly composed of titanium oxide according to the present invention and the subsequent heat treatment are repeatedly performed, and the titanium oxide is mainly used. A method of depositing and forming a transparent conductive film as a component is also preferable.

<Transparent conductive film substrate>
In the transparent conductive film substrate of the present invention, a silicon oxide layer and a transparent conductive film layer mainly composed of titanium oxide formed by the film formation method of the transparent conductive film of the present invention are sequentially laminated on a transparent resin. In addition, the silicon oxide layer is preferably formed by atmospheric pressure plasma treatment. The transparent conductive film substrate having the above structure improves the adhesion between the transparent conductive film layer mainly composed of the titanium oxide and the transparent resin as the base material through the silicon oxide layer, A transparent conductive film substrate having a transparent conductive film mainly composed of titanium oxide having excellent environmental resistance and adhesion performance can be obtained.

That is, when the transparent conductive film mainly composed of titanium oxide is formed on the resin base material, the storage performance of the conductive performance, the environmental resistance performance, the adhesion performance, etc. are compared with those of the ITO, It turned out to be inferior to materials such as SnO ₂ and ZnO.

This is because the titanium oxide TiO ₂ layer (thin film) is in direct contact with the organic polymer molecules of the resin base material compared to materials such as ITO, SnO ₂ , and ZnO that are used as other transparent conductive film materials. It can be inferred that the cause is that the degree of diffusion of the components at the interface is more remarkable than other materials (ITO, SnO ₂ , ZnO, etc.). That is, low-molecular components such as a plasticizer material required for the formation of oligomers and substrate in the resin base material and the interface between the TiO _2, by entering the of the TiO ₂ film, thereby deteriorating the conductivity performance and adhesion performance Presumed to be.

Based on these inferences, the present invention is based on the idea that a silicon oxide film having a Si element smaller than the titanium element can be improved by coating between the resin substrate and the titanium oxide layer. lead to finding a configuration of the invention was thereby found that the performance of TiO ₂ based transparent conductive film is remarkably improved.

[Silicon oxide layer]
In the present invention, as described above, the silicon oxide layer avoids direct contact between the titanium oxide layer (thin film), which is a transparent conductive film material, and the resin base material, and prevents components from diffusing each other at the interface. And has a role of suppressing penetration of organic polymers, oligomers, low molecular components and the like in the resin base material. By depositing the silicon oxide layer between the resin base material and the thin film mainly composed of titanium oxide by the atmospheric pressure plasma CVD method, it is possible to deposit denser silicon oxide having high insulation and blocking properties. preferable. The silicon oxide layer according to the present invention can maintain transparency by setting it to 50 nm or less.

  Examples of the organic silicon compound used as a raw material gas for forming the silicon oxide layer include tetraethylsilane, tetramethylsilane, tetraisopropylsilane, tetrabutylsilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethyldimethoxysilane. , Diethyldiethoxysilane, diethylsilanedi (2,4-pentanedionate), methyltrimethoxysilane, methyltriethoxysilane, ethyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3 -Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypro Rumethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3 -Aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltri Examples thereof include ethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and the like, and all of them are preferably used in the present invention. CanTwo or more of these may be mixed and used at the same time.

  The additive gas is introduced to control the reaction and film quality. As the additive gas, hydrogen, oxygen, nitrogen oxides, ammonia, hydrocarbons, alcohols, organic acids, or moisture may be mixed in an amount of 0.001% to 30% by volume with respect to the gas. Of these, hydrocarbons, alcohols, and organic acids are preferably used. The hydrocarbons are not particularly limited, but include methane, ethane, propane, butane, pentane, hexane, heptane, octane, decane, and the like, and methane is particularly preferably used.

<< Atmospheric pressure plasma processing equipment >>
As an atmospheric pressure plasma processing apparatus suitably used for the method for forming a transparent conductive film mainly composed of titanium oxide of the present invention or the formation of a silicon oxide layer on the transparent conductive substrate of the present invention, each of the methods described below can be used. The atmospheric pressure plasma processing apparatus can be applied without limitation.

  In the present invention, when forming a transparent conductive film containing titanium oxide as a main component on a substrate, using each atmospheric pressure plasma processing apparatus described below, at least a titanium compound, a source gas containing a dopant source, A transparent conductive film mainly composed of titanium oxide formed in the excited gas by exciting a discharge gas such as helium, neon, argon, krypton, xenon, radon, nitrogen, or a reducing gas such as hydrogen gas or water vapor into a plasma state. Is exposed to a constant temperature, preferably at a substrate temperature of 220 ° C. or lower for a certain period of time, a uniform and dense film can be obtained, and the conductivity can be further improved.

  Hereinafter, in the present invention, an atmospheric pressure plasma processing apparatus used for a method for forming a transparent conductive film, or an atmospheric pressure plasma processing apparatus preferably used for a low resistance process in forming a transparent conductive film mainly composed of titanium oxide. Will be described.

  Compared with the plasma CVD method under vacuum, the atmospheric pressure plasma processing method, which performs plasma CVD processing near atmospheric pressure, does not require a reduced pressure and is not only highly productive, but also has a high plasma density. The film speed is high, and further, under a high pressure condition of atmospheric pressure as compared with the conditions of a normal CVD method, the gas mean free path is very short, so that a very homogeneous film can be obtained.

  For example, the transparent conductive film mainly composed of titanium oxide according to the present invention contains a thin film forming gas mainly composed of titanium oxide in a discharge space in which a high-frequency electric field is generated under atmospheric pressure or a pressure in the vicinity thereof. It is formed by supplying a gas to be excited and exposing the substrate to the excited gas.

  The atmospheric pressure or the pressure in the vicinity thereof in the present invention is about 20 kPa to 110 kPa, and 93 kPa to 104 kPa is preferable in order to obtain the good effects described in the present invention.

  The excited gas as used in the present invention means that at least a part of the molecules in the gas move from the existing state to a higher state by obtaining energy. Excited gas molecules, radicalized gas molecules A gas containing ionized gas molecules corresponds to this.

  That is, a thin film forming gas mainly composed of titanium oxide containing a discharge gas and a metal oxide gas (for example, titanium tetraethoxide) is set between the counter electrodes (discharge space) at atmospheric pressure or a pressure in the vicinity thereof. A thin film forming gas mainly composed of titanium oxide is made into a plasma state by applying a high-frequency voltage between the counter electrodes, and a transparent base is formed on the thin film forming gas mainly composed of titanium oxide in the plasma state. By exposing the material, a thin film mainly composed of titanium oxide is formed on the transparent substrate.

  The atmospheric pressure plasma discharge treatment apparatus applicable to the present invention is not particularly limited, but can be broadly divided into the following two methods.

  One method is a method called a plasma jet type atmospheric pressure plasma discharge treatment apparatus, in which a high-frequency voltage is applied between opposing electrodes, a mixed gas containing a discharge gas is supplied between the opposing electrodes, and the mixed gas is supplied. This is a method of forming a transparent conductive layer by assembling and mixing a plasma mixed gas and a transparent conductive layer forming gas and then spraying them on a transparent substrate.

  The other method is a method called a direct-type atmospheric pressure plasma discharge treatment apparatus, in which a mixed gas containing a discharge gas and a transparent conductive layer forming gas are mixed, and then a transparent substrate is supported between the opposing electrodes. In this method, the gas is introduced into the discharge space and a high-frequency voltage is applied between the opposing electrodes to form a transparent conductive layer on the transparent substrate.

  FIG. 1 is a schematic view showing an example of a plasma jet type atmospheric pressure plasma discharge treatment apparatus according to the present invention. The present invention is not limited to this. In addition, the following description may include affirmative expressions for terms and the like, but it shows preferred examples of the present invention and limits the meaning and technical scope of the terms of the present invention. It is not a thing.

  In FIG. 1, the atmospheric pressure plasma discharge processing apparatus 21 has two pairs of electrodes 41 a and 41 b connected to a power source 31 arranged in parallel. At least one of the electrodes 41a and 41b is covered with a dielectric 42, and a high frequency voltage is applied by a power source 31 to a discharge space 43 formed between the electrodes.

  The inside of the electrodes 41a and 41b has a hollow structure 44, and during the discharge, heat generated by the discharge can be obtained by water, oil, etc., and heat exchange can be performed so as to maintain a stable temperature.

  Further, the gas 22 containing the discharge gas necessary for the discharge is supplied to the discharge space 43 through the flow path 24 by each gas supply means not described, and a high frequency voltage is applied to the discharge space 43 to cause plasma discharge. As a result, the gas 22 including the discharge gas is turned into plasma. The plasmaized gas 22 is ejected into the mixing space 45.

  On the other hand, the mixed gas 23 supplied by each gas supply means (not shown) and containing the gas necessary for forming the transparent conductive layer passes through the flow path 25 and is similarly transported to the mixed space 45 where the plasmaized discharge is generated. The gas 22 is merged and mixed, and sprayed onto the transparent substrate placed on the moving stage 47 or the substrate 46 including the transparent substrate on the outermost surface.

  The transparent conductive layer forming gas in contact with the plasma mixed gas is activated by the plasma energy to cause a chemical reaction, and a transparent conductive layer is formed on the substrate 46.

  This plasma jet type atmospheric pressure plasma discharge treatment apparatus has a structure in which a mixed gas containing a gas necessary for forming a transparent conductive layer is sandwiched or surrounded by an activated discharge gas.

  The moving stage 47 on which the base material is mounted has a structure capable of reciprocating scanning or continuous scanning, and can perform heat exchange similar to the above electrode so that the temperature of the base material can be maintained if necessary. It has become.

  In addition, a waste gas exhaust passage 48 for exhausting the gas blown onto the substrate 46 can be attached as necessary. Thereby, unnecessary by-products formed in the space can be quickly removed from the discharge space 45 or the substrate 46.

  This plasma jet type atmospheric pressure plasma discharge treatment apparatus has a structure in which a discharge gas is activated by being converted into plasma and then merged with a mixed gas containing a gas necessary for forming a transparent conductive layer. As a result, it is possible to prevent deposition from being deposited on the electrode surface. However, as described in Japanese Patent Application No. 2003-095367, by attaching a dirt prevention film or the like to the electrode surface, And a gas required for forming the transparent conductive layer may be mixed.

  FIG. 2 is a schematic view showing another example of a plasma jet type atmospheric pressure plasma discharge processing apparatus according to the present invention.

  In FIG. 1, the flow path 24 for supplying the gas 22 including the discharge gas and the flow path 25 for supplying the mixed gas 23 including the gas necessary for forming the transparent conductive layer are provided in parallel. As shown in FIG. 2, a method may be used in which the flow path 24 for supplying the gas 22 containing the discharge gas is formed obliquely and the mixing efficiency with the mixed gas 23 supplied from the flow path 25 is increased.

  Further, in the apparatus described in FIGS. 1 and 2 described above, the high frequency power supply is performed in one frequency band. For example, the method described in Japanese Patent Application Laid-Open No. 2003-96569, the following FIG. As shown in FIG. 4, it can also be implemented by a system in which power sources having different frequencies are installed on the respective electrodes.

  FIG. 3 is a schematic view showing an example of a two-frequency jet type atmospheric pressure plasma discharge treatment apparatus useful for the present invention.

  Although not shown in FIG. 3, the jet type atmospheric pressure plasma discharge treatment apparatus has a gas supply means and an electrode temperature adjustment means in addition to the plasma discharge treatment apparatus and the electric field applying means having two power sources. Device.

The atmospheric pressure plasma discharge processing apparatus 110 has a counter electrode composed of a first electrode 111 and a second electrode 112, and the frequency from the first power supply 121 is from the first electrode 111 between the counter electrodes. A _first high frequency electric field of ω ₁ , electric field strength V ₁ , and current I ₁ is applied, and a second frequency of ω ₂ , electric field strength V ₂ , and current I ₂ from the second power source 122 is applied from the second electrode 112. A high frequency electric field is applied. The first power supply 121 can apply a higher frequency electric field strength (V ₁ > V ₂ ) than the second power supply 122, and the first frequency ω ₁ of the first power supply 121 is higher than the second frequency ω ₂ of the second power supply 122. A low frequency can be applied.

  A first filter 123 is installed between the first electrode 111 and the first power source 121 to facilitate passage of a current from the first power source 121 to the first electrode 111 and a current from the second power source 122. Is designed so that the current from the second power supply 122 to the first power supply 121 does not easily pass.

  In addition, a second filter 124 is installed between the second electrode 112 and the second power source 122 to facilitate passage of current from the second power source 122 to the second electrode, and from the first power source 121. It is designed to ground the current and make it difficult for the current from the first power supply 121 to the second power supply 122 to pass through.

  A gas G is introduced from the gas supply means between the opposing electrodes (discharge space) 113 between the first electrode 111 and the second electrode 112, and a high frequency electric field is applied from the first electrode 111 and the second electrode 112 to generate a discharge. The gas G is blown out in the form of a jet to the lower side of the counter electrode (the lower side of the paper) while filling the processing space formed by the lower surface of the counter electrode and the substrate F with the gas G ° in the plasma state. A thin film is formed in the vicinity of the processing position 114 on the base material F conveyed from the process. During the formation of the thin film, the medium heats or cools the electrode through the pipe from the electrode temperature adjusting means. Depending on the temperature of the base material during the plasma discharge treatment, the properties, composition, etc. of the thin film obtained may change, and it is desirable to appropriately control this. As the temperature control medium, an insulating material such as distilled water or oil is preferably used. During the plasma discharge treatment, it is desired to uniformly adjust the temperature inside the electrode so that the temperature unevenness of the substrate in the width direction or the longitudinal direction does not occur.

  FIG. 3 shows a measuring instrument used for measuring the high-frequency electric field strength (applied electric field strength) and the discharge starting electric field strength. 125 and 126 are high-frequency voltage probes, and 127 and 128 are oscilloscopes.

  FIG. 4 is a schematic view showing an example of another two-frequency plasma jet type atmospheric pressure plasma discharge treatment apparatus in which power sources having different frequencies are installed on the respective electrodes.

  In FIG. 4, the basic configuration is the same as in FIG. 1, but the second high frequency filter 101b and the second high frequency power supply 31b are connected to the electrode 41b, and the electrode 41a is connected to the first high frequency filter 101a and the first high frequency filter 101a. One high frequency power supply 31a is connected, and two different high frequency voltages are applied to each.

  Further, by arranging these plasma jet type atmospheric pressure plasma discharge treatment apparatuses in the scanning direction of a plurality of stages, the film forming ability can be improved.

  In addition, although not shown in this plasma jet type atmospheric pressure plasma discharge treatment apparatus, by making a structure that surrounds the electrode and the entire stage and does not enter the outside air, the inside of the apparatus can be in a constant gas atmosphere, A desired high-quality transparent antistatic film can be formed.

  FIG. 5 is a schematic view showing an example of a direct atmospheric pressure plasma discharge treatment apparatus applicable to the present invention.

  In the direct atmospheric pressure plasma discharge processing apparatus shown in FIG. 5, two electrodes 41 connected to the power source 31 are provided side by side so as to be parallel to the moving stage electrode 47. At least one of the electrodes 41 and 47 is covered with a dielectric 42, and a high frequency voltage is applied by the electrode 31 to a space 43 formed between the electrodes 41 and 47.

  Note that the inside of the electrode 41 and the moving stage 47 has a hollow structure 44, so that heat generated by the discharge can be removed by water, oil, etc. during discharge, and heat exchange can be performed so as to maintain a stable temperature. Yes.

  Further, by each gas supply means (not shown), the gas 22 containing the discharge gas necessary for the discharge passes through the flow path 24, and the mixed gas 23 containing the gas necessary for forming the transparent conductive layer becomes the flow path 25. And are mixed and mixed in the mixing space 45. The mixed gas G passes between the electrodes 41 and is supplied to the space 43 between the electrodes 41 and 47. When a high frequency voltage is applied to the space 43, plasma discharge is generated, and the gas G is turned into plasma. . The gas G for forming the transparent conductive layer is activated by the plasma gas G to cause a chemical reaction, and the transparent conductive layer is formed on the base material (transparent base material or liquid crystal optical element unit including the transparent base material on the outermost surface) 46. A layer is formed.

  The stage 47 on which the substrate is mounted has a structure capable of reciprocating scanning or continuous scanning, and can perform heat exchange similar to the above electrodes so that the temperature of the substrate can be maintained as necessary. It has become.

  In addition, a waste gas exhaust passage 48 for exhausting the gas blown onto the substrate 46 can be attached as necessary. Thereby, unnecessary by-products formed in the space can be quickly removed from the discharge space 45 or the substrate 46.

  Also, as described in Japanese Patent Application No. 2003-095367, a structure may be adopted in which a discharge gas and a gas necessary for forming a transparent conductive layer are mixed before discharge by attaching a dirt prevention film to the electrode surface. it can.

  In the apparatus shown in FIG. 5, the high-frequency power source is used in one frequency band. For example, the method described in Japanese Patent Application Laid-Open No. 2003-96569, or each electrode as shown in FIG. It can also be implemented by installing a power supply.

  FIG. 6 is a schematic diagram showing an example of another two-frequency direct atmospheric pressure plasma discharge treatment apparatus in which power sources having different frequencies are installed on the respective electrodes.

  In FIG. 6, the basic configuration is the same as in FIG. 5, but the first high frequency filter 101a and the first high frequency power supply 31a are connected to the two electrodes 41, and the moving stage electrode 47 is connected to the first high frequency power supply 31a. The two high frequency filters 101b and the second high frequency power supply 31b are connected to each other so that different high frequency voltages of two frequencies are applied.

  By arranging these direct type atmospheric pressure plasma discharge treatment apparatuses in the scanning direction of a plurality of stages, the film forming ability can be improved.

  Although not shown in this direct type atmospheric pressure plasma discharge treatment apparatus, the structure inside the electrode and the stage and surrounding air does not enter, so that the inside of the apparatus can be kept in a certain gas atmosphere, which is desired. It is possible to form a high-quality thin film.

  In the plasma CVD apparatus described above, as a high frequency power source, Shinko Electric high frequency power source (3 kHz), Shinko Electric high frequency power source (5 kHz), Shinko Electric high frequency power source (15 kHz), Shinko Electric high frequency power source (50 kHz), HEIDEN High frequency power source manufactured by R & D Laboratories (continuous mode, 100 kHz), high frequency power source manufactured by Pearl Industry (200 kHz), high frequency power source manufactured by Pearl Industry (800 kHz), high frequency power source manufactured by Pearl Industrial (2 MHz), high frequency power source manufactured by JEOL (13.56 MHz) A high frequency power source (27 MHz) manufactured by Pearl Industry, a high frequency power source (150 MHz) manufactured by Pearl Industry, or the like can be used. Alternatively, a power source that oscillates at 433 MHz, 800 MHz, 1.3 GHz, 1.5 GHz, 1.9 GHz, 2.45 GHz, 5.2 GHz, or 10 GHz may be used.

In the present invention, the power applied between the opposing electrodes is to supply a power (power density) of 1 W / cm ² or more to the second electrode (second high frequency electric field) to excite the discharge gas to generate plasma, Energy is applied to the thin film forming droplet to form a thin film. The upper limit value of the power supplied to the second electrode is preferably 50 W / cm ² , more preferably 20 W / cm ² . The lower limit is preferably 1.2 W / cm ² . The discharge area (cm ² ) refers to the area in the range where discharge occurs in the electrode.

Further, by supplying power (output density) of 1 W / cm ² or more to the first electrode (first high frequency electric field), the output density can be improved while maintaining the uniformity of the second high frequency electric field. Can do. Thereby, a further uniform high-density plasma can be generated, and a further improvement in film formation speed and an improvement in film quality can be achieved. Preferably it is 5 W / cm ² or more. The upper limit value of the power supplied to the first electrode is preferably 50 W / cm ² .

  Here, the waveform of the high-frequency electric field is not particularly limited. There are a continuous sine wave continuous oscillation mode called a continuous mode, an intermittent oscillation mode called ON / OFF intermittently called a pulse mode, and either of them may be adopted, but at least the second electrode side (second The high-frequency electric field is preferably a continuous sine wave because a denser and better quality film can be obtained.

  As described above, the method for forming a transparent conductive film according to the present invention has been described using an atmospheric pressure plasma apparatus. The same apparatus can be applied to the formation of a silicon oxide layer on a transparent conductive film substrate (resistance treatment, annealing treatment). For example, in the case of heat treatment by atmospheric pressure plasma treatment, a reactive gas such as helium, neon, argon, krypton, xenon, radon, nitrogen and a reducing gas containing hydrogen gas or water vapor is put into a plasma state. High thin film uniformity can be obtained by exposing the formed transparent conductive film mainly composed of titanium oxide to the excited gas at a constant temperature, preferably at a substrate temperature of 220 ° C. or less for a certain time. A dense and low resistance film can be obtained. When a silicon oxide layer is formed by atmospheric pressure plasma treatment, the space between the counter electrodes (discharge space) is set to atmospheric pressure or a pressure near it, and a rare gas such as helium, argon, or nitrogen is used as the discharge gas. A metal oxide forming gas containing a silicon oxide layer forming gas (raw material gas) such as ethoxyethane is introduced between the counter electrodes, and a high frequency voltage is applied between the counter electrodes to bring the silicon oxide layer forming gas into a plasma state. The substrate is exposed to a silicon oxide layer forming gas in a plasma state to form a silicon oxide layer on the transparent resin.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

Example 1
<< Preparation of Transparent Conductive Sample 1: Present Invention >>
[Preparation of Substrate 1]
A biaxially stretched polyethylene terephthalate (PET) film with a thickness of 200 mm x 200 mm and a thickness of 125 μm is used as a film substrate, and a clear hard coat layer and an undercoat ceramic layer are sequentially laminated in the following procedure to produce a substrate 1 did.

[Formation of clear hard coat layer]
(Clear hard coat layer (CHC layer) coating composition)
Dipentaerythritol hexaacrylate monomer 60 parts by mass Dipentaerythritol hexaacrylate dimer 20 parts by mass Dipentaerythritol hexaacrylate trimer or higher component 20 parts by mass Irgacure 184 (manufactured by Ciba Specialty Chemicals) 2 parts by mass Isopropyl alcohol 50 parts by weight Ethyl acetate 50 parts by weight Methyl ethyl ketone 50 parts by weight The above clear hard coat layer coating composition was applied onto the film base by a coater under the condition that the dry film thickness was 6 μm, and then 80 After drying in a drying section set at ° C., ultraviolet rays were irradiated using an ultraviolet irradiation facility. The ultraviolet lamp used for the ultraviolet irradiation used an output of 3 kW (high pressure mercury type manufactured by Eye Graphic Co., Ltd.), and the illuminance was 0.1 W / cm ² . Further, the holding plate was set so that the surface temperature of the substrate was 25 ° C. during irradiation.

[Formation of subbing ceramic layer]
Using the two-frequency direct atmospheric pressure plasma processing apparatus shown in FIG. 6, a SiO ₂ film was formed under the condition that the film thickness was 25 nm according to the following conditions.

(Atmospheric pressure plasma discharge treatment equipment)
<Power supply conditions>
Power source 1: high frequency side 13.56 MHz 6 W / cm ²
Power supply 2: Low frequency side 100 kHz 5 W / cm ²
<Gas conditions>
Source gas: Tetraethoxysilane (TEOS) was vaporized by bubbling as a raw material of SiO ₂ (N ₂ gas: 1 slm, 40 ° C.)
Discharge gas N ₂ : 60 slm
Auxiliary gas O ₂ : 6 slm
<Moving base electrode>
The movable gantry electrode was manufactured by spraying alumina as a dielectric on the surface of a titanium plate having a width of 200 mm and a length of 300 mm. In addition, a heat sink and a heater were installed on the back side so that the temperature of the substrate surface was always constant.

Dielectric thickness: 1mm
Electrode width: 200mm
Material: Titanium Temperature of moving platform electrode: 100 ° C
A substrate was placed on the movable gantry electrode, and a thin film was formed while continuously scanning to form a 25 nm SiO ₂ thin film.

[Production of Titanium Oxide Transparent Conductive Film 1]
A titanium oxide transparent conductive film 1 having niobium as a dopant was formed on a base material 1 according to the conditions shown below using a direct dual frequency method shown in FIG. 6 as an atmospheric pressure plasma discharge treatment apparatus.

[Power supply conditions]
Power source 1: High frequency power source manufactured by Pearl Industry, high frequency side 13.56 MHz 5 W / cm ²
Power source 2: SEREN high frequency power source, low frequency side 100 kHz 5 W / cm ²
[Electrode conditions]
The square electrode of the second electrode was manufactured by spraying alumina as a dielectric on a 30 mm square hollow titanium pipe.

Dielectric thickness: 1mm
Electrode width: 300mm
Applied electrode temperature: 90 ° C
Second electrode slit gap: 1.0 mm
Gap between electrodes: 1.0mm
[Gas condition]
(Raw material gas)
Tetrizopropoxy titanium (TIPT) was vaporized by bubbling as a raw material for forming the TiO ₂ film (N ₂ gas: 3 slm, 60 ° C.).

Further, pentaethoxyniobium as a doping material was vaporized by bubbling (N ₂ gas: 3 slm, 80 ° C.).

(Discharge gas) N ₂ : 60 slm
(Auxiliary gas) H ₂ : 0.3 slm
(Moving base electrode)
The movable gantry electrode was manufactured by spraying alumina as a dielectric on the surface of a titanium plate having a width of 200 mm and a length of 300 mm. In addition, a heat sink and a heater were installed on the back side so that the temperature of the substrate surface was always constant.

Dielectric thickness: 1mm
Electrode width: 200mm
Material: Titanium Temperature of mobile pedestal electrode: The temperature of the pedestal is adjusted to the film formation temperature shown in Table 1. The substrate 1 is placed on the mobile pedestal electrode, and film formation is performed while continuously scanning. A transparent conductive film sample 1 was prepared by forming a 100 nm Nb-doped TiO ₂ film.

<< Preparation of Transparent Conductive Film Sample 2: Present Invention >>
In the production of the transparent conductive film sample 1, the transparent conductive film was formed in the same manner except that the titanium oxide transparent conductive film 2 was formed under the following gas conditions using a compound containing tantalum as a dopant during the titanium oxide transparent conductive film. Sample 2 was prepared.

[Preparation of Titanium Oxide Transparent Conductive Film 2]
[Gas condition]
(Raw material gas)
Tetrizopropoxy titanium (TIPT) was vaporized by bubbling as a raw material for forming the TiO ₂ film (N ₂ gas: 3 slm, 60 ° C.).

Moreover, pentaethoxy tantalum was vaporized by bubbling as a doping material (N ₂ gas: 3 slm, 90 ° C.).

(Discharge gas) N ₂ : 60 slm
(Auxiliary gas) H ₂ : 1.0 slm
The other conditions were the same as the conditions for forming the titanium oxide transparent conductive film 1.

The substrate 1 was placed on the movable gantry electrode, and film formation was performed while continuously scanning to form a Ta-doped TiO ₂ film of about 100 nm, and a transparent conductive film sample 2 was produced.

<< Preparation of Transparent Conductive Sample 3: Present Invention >>
In the production of the transparent conductive film sample 1, the base material is changed to a commercially available non-alkali glass (Corning Inc., # 1737) of 200 mm × 200 mm and a thickness of 0.7 mm instead of PET, and a titanium oxide transparent conductive film is produced. A transparent conductive film sample 3 was produced in the same manner except that the base material temperature was changed to 200 ° C.

<< Preparation of Transparent Conductive Film Sample 4: Present Invention >>
In the production of the transparent conductive film sample 3, after forming the transparent conductive film, the transparent conductive film sample 3 was produced in the same manner except that a low-temperature thermal annealing method was performed as a heat treatment according to the following method.

(Low-temperature thermal annealing method: reduction annealing method)
A glass substrate having a transparent conductive film is installed in the chamber, and after reaching an ultimate vacuum of 5 × 10 ⁻⁶ Pa or less, hydrogen gas is introduced until the gas pressure becomes 0.9 × 10 ³ kPa. Then, annealing was performed for 5 minutes under the condition of the substrate temperature of 200 ° C. The substrate temperature was raised to 200 ° C. over about 15 minutes, and after a desired time (annealing time), the heat removal time was set to 15 minutes, and after purging with nitrogen, the substrate was taken out from the chamber.

<< Preparation of Transparent Conductive Sample 5: Comparative Example >>
In the production of the transparent conductive film sample 3, a transparent conductive film sample 5 was produced in the same manner except that the transparent conductive film was formed by the following sputtering method instead of the atmospheric pressure plasma treatment method.

(Sputtering method)
TiO ₂ powder (99.99%) and Nb ₂ O ₅ powder (99.99%) were mixed at a ratio of 95: 5, then molded and fired, and a 20 cm diameter TiO ₂ —Nb ₂ O ₅ high density A sintered body (target) was produced. The obtained target was attached to a batch type DC magnetron sputtering apparatus to form a film. The magnetic flux density on the target was 1000 Gauss. The ultimate vacuum in the chamber was 5 × 10 ⁻⁶ Pa or less, and the gas pressure during sputtering was 2 × 10 ⁻⁴ Pa. Argon gas and a mixed gas of argon and oxygen were used as the sputtering gas, and were introduced into the chamber by another system. Under this condition, an Nb: TiO ₂ thin film having a film thickness of 100 nm was formed on a glass substrate held on a 200 ° C. heat insulating plate. The mass ratio of argon to oxygen was 500: 1.

<< Evaluation of transparent conductive film sample >>
About each produced said transparent conductive film sample, according to the following method, the measurement of the light transmittance, the measurement of resistance value, and evaluation of planarity were performed.

(Measurement of light transmittance)
The light transmittance at 550 nm of each transparent conductive film sample and each substrate used for it was measured using a spectrophotometer V-530 manufactured by JASCO, and the light transmittance was determined according to the following equation.

Light transmittance = (Transmittance of transparent conductive film sample) / (Transmittance of substrate) × 100
(Measurement of resistance value)
About each transparent conductive film sample and each transparent conductive film sample before performing the resistance reduction process (annealing treatment), resistance value (Ω / □) using Hiresta MCP-HT450 type, probe MCP-HTP12 manufactured by Mitsubishi Chemical Was measured. The numerical value of the resistance value measured here has a certain degree of correlation with the homogeneity of the formed transparent conductive film, and the lower the resistance value, the higher the film homogeneity.

  The results obtained as described above are shown in Table 1.

  As is clear from the results shown in Table 1, it can be seen that the transparent conductive film sample prepared according to the method for forming a transparent conductive film of the present invention is superior in light transmission performance and resistance performance to the comparative example. In particular, it can be seen that the sample in which the transparent conductive film is formed by the atmospheric pressure plasma CVD method has an excellent resistance value even in a system in which heat treatment is not performed.

Claims (9)

  A transparent conductive film forming method for forming a transparent conductive film containing titanium oxide as a main component on a base material by plasma CVD, wherein the plasma CVD process comprises at least a titanium compound, a dopant raw material, and a reducing gas. Forming a thin film mainly composed of titanium oxide on the base material by introducing a reactive gas containing it into a discharge space to form a plasma state and exposing the base material to the reactive gas in a plasma state. A method for forming a transparent conductive film, which is characterized.   2. The method for forming a transparent conductive film according to claim 1, wherein the plasma CVD process is an atmospheric pressure plasma process for forming a film under an atmospheric pressure or a pressure near atmospheric pressure.   The method for forming a transparent conductive film according to claim 1 or 2, wherein the reducing gas is hydrogen gas.   The method for forming a transparent conductive film according to any one of claims 1 to 3, wherein the temperature of the base material during the plasma CVD process is 220 ° C or lower.   The method for forming a transparent conductive film according to any one of claims 1 to 4, wherein after the plasma CVD process is performed, a heat treatment is performed in an atmosphere containing at least hydrogen gas. .   6. The method for forming a transparent conductive film according to claim 1, wherein the dopant raw material is a niobium-containing compound.   The method for forming a transparent conductive film according to claim 1, wherein the base material is a transparent resin.   A transparent conductive film substrate in which a silicon oxide layer and a transparent conductive film layer mainly composed of titanium oxide are sequentially laminated on a transparent resin, wherein the transparent conductive film layer mainly composed of titanium oxide is A transparent conductive film substrate formed by the method for forming a transparent conductive film according to any one of claims 1 to 7.   The transparent conductive film substrate according to claim 8, wherein the silicon oxide layer is formed by atmospheric pressure plasma treatment.