JP2012140276A - Zinc oxide-based transparent conductive film forming material, target using the same, method for forming zinc oxide-based transparent conductive film, and transparent conductive substrate - Google Patents

Abstract

[PROBLEMS] To use a target for depositing a transparent conductive film having a suitable etching rate during patterning, having chemical durability such as weather resistance and heat resistance while maintaining conductivity that can be practically used. A zinc oxide-based transparent conductive film forming material, a method for producing the material, a target using the same, and a method for forming a zinc oxide-based transparent conductive film are provided.
A transparent conductive film-forming material of the present invention is a zinc oxide-based transparent conductive film-forming material containing zinc oxide as a main component, containing at least one of gallium fluoride and aluminum fluoride, and further containing titanium. The ratio of the number of titanium atoms to the total number of metal atoms is more than 2% and not more than 10%, and the ratio of the number of metal atoms of one or both of gallium fluoride and aluminum fluoride to the total number of metal atoms is 0.1% or more and 5 %, And as a titanium source, an oxide sintered body using low-valent titanium oxide represented by the general formula: TiO _2-X (X = 0.1-1).
[Selection figure] None

Description

  The present invention is an oxide sintering useful as a target used when forming a zinc oxide-based transparent conductive film by sputtering, ion plating, pulse laser deposition (PLD), or electron beam (EB) vapor deposition. The present invention relates to a zinc oxide-based transparent conductive film forming material, a target using the same, a method for forming a zinc oxide-based transparent conductive film, and a transparent conductive substrate formed from the target.

The transparent conductive film is a film having both visible light transmittance and electrical conductivity, and is used in a wide range of fields such as solar cells, liquid crystal display elements, and electrodes of light receiving elements.
As a transparent conductive film, a tin-doped indium oxide (ITO) film in which tin oxide is added to indium oxide is known. The ITO film is formed by sputtering, ion plating, pulsed laser deposition (PLD), electron beam ( EB) Manufactured and used by film forming methods such as vapor deposition and spraying.
However, indium as a raw material is a rare metal, and there are problems in the amount of resources, price, and the like, so an alternative material is required.

As alternative material candidates, transparent conductive films such as zinc oxide, tin oxide, titanium oxide, and magnesium hydroxide have been proposed.
Among them, as zinc oxide-based transparent conductive films, aluminum-doped zinc oxide (AZO) films and gallium-doped zinc oxide (GZO) films in which aluminum oxide or gallium oxide, which is a trivalent element, is added to zinc oxide have been proposed, A film having conductivity and transparency comparable to that of an ITO film is manufactured.
As a method for forming these transparent conductive films, a PLD method that is a vacuum film formation method, a sputtering method, an ion plating method, a spray method that is a non-vacuum film formation method, a sol-gel method, and the like have been proposed.

  As for the zinc oxide-based transparent conductive film, as described above, a value comparable to that of the ITO film has been obtained for transparency and conductivity, but durability (weather resistance) against temperature and humidity is inferior, In addition, there is a problem in that patterning is difficult because the etching rate is too high during patterning when manufacturing an element.

It is known that such properties as weather resistance and chemical vulnerability can be controlled by adding different kinds of metal elements. Patent Document 1 discloses that titanium oxide TiO ₂ and gallium oxide are added to zinc oxide. It is described that a zinc oxide-based transparent conductive film having excellent durability can be obtained by a sputtering method or an ion plating method using a co-doped target.

  However, in Patent Document 1, since the Ti element, which is a tetravalent element, is substituted and dissolved in the site in the crystal of the zinc element, which is a divalent element, the charge balance is greatly lost, and the crystal structure is distorted. Therefore, it is difficult to express sufficient conductivity.

Japanese Patent No. 429581

  The present invention solves the above-mentioned problems, has a chemical durability such as weather resistance and heat resistance while maintaining conductivity that can withstand practical use, and has a suitable etching rate during patterning. PROBLEM TO BE SOLVED: To provide a zinc oxide-based transparent conductive film forming material that can be used as a target for forming a conductive film, a target using the same, a method for forming a zinc oxide-based transparent conductive film, and a transparent conductive substrate And

As a result of various studies to solve the above-mentioned problems, the present inventors have made zinc oxide as a base material, and a predetermined amount of aluminum fluoride or gallium fluoride, and further, low-valent titanium oxide (for example, titanium element). The transparent conductive film produced by using the zinc oxide-based transparent conductive film forming material obtained by adding 2 or 3) has sufficient weather resistance with respect to temperature and humidity, and more appropriate etching. It has been found that it has a rate, and the present invention has been completed.
In particular, it has been found that by doping with fluorine, the carrier electron mobility is increased, so that the resistance can be further reduced without reducing the near-infrared region transparency (780 nm to 1500 nm).
In addition, when fluorine is formed by a vacuum process, attempts have been made to dope fluorine by introducing a fluorine-based gas into the film formation atmosphere, but it is difficult to introduce fluorine uniformly and with good reproducibility. However, it has been found that by doping fluorine in the oxide sintered body, it is possible to introduce fluorine into the film uniformly and with good reproducibility.

That is, this invention consists of the following structures.
(1) A zinc oxide-based transparent conductive film forming material containing zinc oxide as a main component, containing at least one of gallium fluoride and aluminum fluoride, and further containing titanium, and the ratio of the number of titanium atoms to the total number of metal atoms Is more than 2% and 10% or less, the ratio of the number of metal atoms of one or both of gallium fluoride and aluminum fluoride to the total number of metal atoms is 0.1% or more and 5% or less, and as a titanium source, A zinc oxide-based transparent conductive film-forming material, which is an oxide sintered body using low-valent titanium oxide represented by the formula: TiO _2-X (X = 0.1-1).
(2) The zinc oxide-based transparent conductive film forming material according to (1), wherein the relative density of the oxide sintered body is 93% or more.
(3) A target used for film formation by sputtering, ion plating, pulse laser deposition (PLD), or electron beam (EB) vapor deposition, wherein the zinc oxide according to (1) or (2) A target obtained by processing a transparent conductive film forming material.
(4) A zinc oxide-based transparent conductive film is formed by sputtering, ion plating, pulsed laser deposition (PLD), or electron beam (EB) evaporation using the target described in (3). A method for forming a zinc oxide-based transparent conductive film, wherein:
(5) A transparent conductive substrate comprising a zinc oxide-based transparent conductive film formed by the method for forming a zinc oxide-based transparent conductive film according to (4) above on a transparent substrate.

Since the transparent conductive film-forming material of the present invention is mainly composed of zinc oxide and doped with aluminum fluoride or gallium fluoride and a low-valent titanium element such as trivalent or divalent, a sputtering method, It can be suitably used as a target for forming a transparent conductive film by ion plating, PLD, EB vapor deposition, etc., and the formed transparent conductive film has an appropriate etching rate during patterning. .
In addition, the formed zinc oxide-based transparent conductive film has excellent electrical conductivity as well as high weather resistance and chemical durability [heat resistance, moisture resistance, weather resistance, chemical resistance (alkali resistance, acid resistance, etc.)]. Prepare. In addition, the transparent conductive film formed in this manner is extremely useful industrially because it has the advantage that it does not require toxic indium, which is a rare metal.

  Hereinafter, the present invention will be described in more detail. However, the following description is one embodiment, and the present invention is not limited by the following description unless it departs from the gist of the present invention.

(Zinc oxide-based transparent conductive film forming material)
The material for forming a zinc oxide-based transparent conductive film of the present invention is an oxide sintered body substantially composed of zinc, titanium, aluminum and / or gallium, oxygen, and fluorine.
Here, “substantially” means that 99% or more of all atoms constituting the oxide sintered body are composed of zinc, titanium, gallium and / or aluminum, fluorine, and oxygen. .

  In the oxide sintered body in the present invention, it is important that the number of titanium atoms is contained in a ratio of more than 2% and not more than 10% with respect to the total number of metal atoms. The ratio is 3% or more and 9% or less, more preferably 4% or more and 8% or less with respect to the total number of metal atoms. If the proportion of titanium atoms is less than 2%, chemical durability such as chemical resistance of a film formed using this oxide sintered body as a target may be insufficient. On the other hand, when the ratio of the number of atoms of titanium exceeds 10%, titanium oxide cannot be sufficiently substituted and dissolved in zinc sites, and the conductivity and transparency of a film formed using this oxide sintered body as a target are lowered. There is a fear.

In the oxide sintered body, the number of metal atoms of gallium fluoride or aluminum fluoride, that is, the number of atoms of gallium or aluminum is a ratio of 0.1% to 5% with respect to the total number of metal atoms. It is good. If the ratio of the number of metal atoms of gallium fluoride or aluminum fluoride is less than 0.1%, the effect of improving the conductivity of the formed film may be insufficient. On the other hand, if it exceeds 5%, gallium or aluminum cannot be completely substituted and dissolved in the zinc site and is precipitated at the crystal grain boundary, so that the conductivity and transmittance of the formed film may be insufficient.
Both AlF ₃ and GaF ₃ may be used. In that case, the total amount of the metal atoms of AlF ₃ and GaF ₃ only needs to satisfy the condition that the ratio is 0.1% or more and 5% or less with respect to the total number of metal atoms as described above.

The oxide sintered body in the present invention is composed of a zinc oxide phase, a zinc titanate compound phase, an aluminum fluoride phase and / or a gallium fluoride phase, or a zinc titanate compound phase and a fluoride. It is preferably composed of an aluminum phase and / or a gallium fluoride phase. When the zinc titanate compound phase is contained in the oxide sintered body in this way, the strength of the oxide sintered body itself increases, so film formation under severe conditions (high power, etc.) even under film formation conditions There will be no cracks in the material.
It is preferable that the oxide sintered body does not substantially contain a titanium oxide phase.
Here, the zinc titanate compound phase specifically includes ZnTiO ₃ , Zn ₂ TiO ₄ , titanium element, gallium element, aluminum element at these zinc sites, and fluorine at the oxygen site. Including oxygen introduced vacancies; non-stoichiometric compositions with slightly different Zn / Ti ratios from these compounds.
Specifically, the zinc oxide phase includes ZnO, titanium element, gallium element, aluminum element, and fluorine element dissolved therein; oxygen deficiency introduced; non-stoichiometric amount due to zinc deficiency It also includes those that have a theoretical composition. The zinc oxide phase usually has a wurtzite structure.
Specifically, the titanium oxide phase is low-atomized titanium oxide such as Ti ₂ O ₃ (III) or TiO (II).

The oxide sintered body in the present invention is obtained by mixing and press-molding zinc oxide powder, titanium oxide powder, aluminum fluoride powder and / or gallium fluoride powder.
As the titanium oxide powder, titanium oxide (III) and titanium oxide (II) are preferable.

  In addition to the essential elements zinc, titanium, aluminum and / or gallium, oxygen, fluorine, and additional elements described later, the oxide sintered body in the present invention includes other elements such as indium, iridium, ruthenium, rhenium, and the like. May be contained as an impurity. The total content of elements contained as impurities is preferably 0.5% or less in terms of atomic ratio with respect to the total amount of all metal elements constituting the oxide sintered body.

  The oxide sintered body in the present invention may also contain at least one element selected from the group consisting of tin, silicon, germanium, zirconium, and hafnium (hereinafter, these may be referred to as “additive elements”). preferable. By containing such an additive element, the specific resistance of the oxide sintered body itself can be reduced in addition to the specific resistance of the film formed using the oxide sintered body as a target. For example, the deposition rate during DC sputtering depends on the specific resistance of the oxide sintered body as a sputtering target, and the productivity during film formation is improved by lowering the specific resistance of the oxide sintered body itself. be able to. When an additive element is contained, the total content is preferably 0.05% or less with respect to the total amount of all metal elements constituting the oxide sintered body in terms of atomic ratio. When there is more content of an additional element than the said range, there exists a possibility that the specific resistance of the film | membrane formed using an oxide sintered compact as a target may increase.

  The oxide sintered body in the present invention has a relative density of 93% or more, preferably 95 to 100%. Here, the relative density is defined as the density of the oxide sintered body divided by the theoretical density and multiplied by 100. If the relative density is less than 93%, the characteristic of the oxide sintered body, that is, stable discharge and a high film formation rate may be impaired.

(Method for producing zinc oxide-based transparent conductive film forming material)
The zinc oxide-based transparent conductive film forming material of the present invention is a raw material powder containing a mixed powder of low-valent titanium oxide powder, zinc oxide powder or zinc hydroxide powder, and aluminum fluoride powder and / or gallium fluoride powder. After being molded, the obtained molded body is manufactured by sintering.

  The raw material powder may include a mixed powder of titanium oxide powder, zinc oxide powder or zinc hydroxide powder, aluminum fluoride powder and / or gallium fluoride powder. Alternatively, the mixed powder may contain other elements such as, for example, indium, iridium, ruthenium, and rhenium; powders such as additive elements within the above-described range.

As the low-valent titanium oxide powder, low-valent titanium oxide powders such as Ti ₂ O ₃ and TiO can be used, and Ti ₂ O ₃ powder is particularly preferable. Because the crystal structure of Ti ₂ O ₃ is trigonal and the zinc oxide mixed with it is hexagonal wurtzite, the symmetry of the crystal structure is the same, and the solid solution is substituted during solid phase sintering. Because it is easy to do.
The low valence titanium oxide referred to here is not only an oxide of titanium having an integer valence of TiO (II) and Ti ₂ O ₃ (III), but also Ti ₃ O ₅ , Ti ₄ O ₇ and Ti _6. Including O ₁₁ , Ti ₅ O ₉ , Ti ₈ O _{15 and the} like, it is represented by the general formula: TiO _{2 -X} (X = 0.1-1). The low-valent titanium oxide in the present invention is a novel low-valent titanium oxide represented by the general formula TiO _{2 -X} . The structure of this low-valence titanium oxide can be confirmed by the results of instrumental analysis such as an X-ray diffractometer (X-Ray Diffraction, XRD) and an X-ray photoelectron spectrometer (X-ray Photoelectron Spectroscopy, XPS).

It is difficult to produce a single component of titanium oxide represented by the general formula TiO _2-X (X = 0.1-1), and it is obtained as a mixture. Usually, it can be produced by heating titanium oxide (TiO ₂ ) in a reducing atmosphere such as a hydrogen atmosphere using carbon or the like as a reducing agent. By adjusting the hydrogen concentration, the amount of carbon as a reducing agent, and the heating temperature, the ratio of the low-valent titanium oxide mixture can be controlled.

As the zinc oxide powder, a powder of ZnO or the like having a wurtzite structure is usually used, and a powder obtained by firing this ZnO in advance in a reducing atmosphere and containing oxygen deficiency may be used.
The zinc hydroxide powder may be either amorphous or crystalline.
The aluminum fluoride powder is AlF ₃ powder.
The gallium fluoride powder is GaF ₃ powder.
Each raw material powder preferably has an average particle size of 1 μm or less.

  In the raw material powder, the ratio of the number of titanium atoms to the total number of metal atoms is more than 2% and not more than 10%, preferably not less than 3% and not more than 9%, more preferably 4%, like the oxide sintered body described above. The ratio is preferably 8% or less.

Further, the ratio of the number of metal atoms of gallium fluoride powder or aluminum fluoride powder to the total number of metal atoms, that is, the number of atoms of gallium or aluminum is 0.1% or more and 5% as in the oxide sintered body described above. The following ratio is preferable.
Even when both gallium fluoride powder and aluminum fluoride powder are used as the raw material powder, it is sufficient that the total amount thereof satisfies the condition that the ratio is 0.1% or more and 5% or less with respect to the total number of metal atoms.

  When using a mixed powder of low-valent titanium oxide powder, zinc oxide powder or zinc hydroxide powder, aluminum fluoride powder and / or gallium fluoride powder as the raw material powder, the mixing ratio of each powder is used. What is necessary is just to set suitably according to the kind of compound (powder) so that the ratio of the number of atoms of titanium and the ratio of the number of atoms of gallium or aluminum may become in the range mentioned above in the oxide sintered compact finally obtained. In addition, each raw material powder may be only 1 type, respectively, and 2 or more types may be sufficient as it.

  At that time, considering that zinc has a higher vapor pressure than titanium and is likely to be volatilized when sintered, the desired composition of the desired oxide sintered body (atomic ratio of Zn and Ti), It is preferable to set the mixing ratio in advance so that the amount of zinc increases. Specifically, the easiness of volatilization of zinc varies depending on the atmosphere during sintering.For example, when zinc oxide powder is used, only the volatilization of zinc oxide powder itself occurs in an air atmosphere or an oxidizing atmosphere. When sintered in a reducing atmosphere, the zinc oxide is reduced and becomes metal zinc that is more easily volatilized than zinc oxide, so the amount of zinc lost increases (however, as described later, it is once sintered) After that, when annealing is performed in a reducing atmosphere, zinc is already difficult to evaporate because it is already a complex oxide at the time of annealing.

  Therefore, the amount of zinc to be increased with respect to the target composition may be set in consideration of the sintering atmosphere or the like. For example, it is desirable when sintering is performed in an air atmosphere or an oxidizing atmosphere. What is necessary is just to be about 1.1 to 1.3 times the amount of the desired atomic number ratio when sintering in a reducing atmosphere, about 1.0 to 1.05 times the amount of the atomic number ratio. In addition, each compound (powder) used as the raw material powder may be only one kind or two or more kinds.

  The raw material powder may be pulverized before being molded. By performing the pulverization treatment, the raw material powder is adjusted to have a narrow particle size distribution, and can be uniformly solid-phase sintered in the sintering described later to obtain a high-density oxide sintered body. it can.

  The method for pulverization is not particularly limited. For example, when media is used, a method using a pulverizer equipped with a bead mill, a ball mill, a planetary mill, a sand grinder, a vibration mill, or an attritor, and no media are used. Examples thereof include a method using a wet ultrahigh pressure atomizer such as a jet mill, a nanomizer, and a starburst.

The method for forming the raw material powder is not particularly limited. For example, the raw material powder and an aqueous solvent are mixed, and the resulting slurry is sufficiently mixed by wet mixing, followed by solid-liquid separation, drying, Granulation is performed, and the resulting granulated product may be formed.
The aqueous solvent contains water as a main component and may be water alone, or may be a mixture of water and alcohol such as methanol or ethanol.
The wet mixing may be performed by, for example, a wet ball mill using a hard ZrO ₂ ball or a vibration mill, and the mixing time when using the wet ball mill or the vibration mill is preferably about 12 to 78 hours. In addition, although raw material powder may be dry-mixed as it is, wet mixing is more preferable.

For solid-liquid separation / drying / granulation, known methods may be employed. When the obtained granulated product is molded, for example, the granulated product is put into a mold, and a pressure of 1 ton / cm ² or more is applied using a cold molding machine such as a cold press or a cold isostatic press. Can be molded. At this time, when hot forming is performed using a hot press or the like, it is disadvantageous in terms of manufacturing cost and it is difficult to obtain a large-sized sintered body. In addition, when obtaining a granulated material as a molded object, what is necessary is just to granulate by a well-known method after drying, In that case, it is preferable to mix a binder with raw material powder. As the binder, for example, polyvinyl alcohol, vinyl acetate and the like can be used.

Sintering of the obtained molded body is performed in any of an air atmosphere, a reducing atmosphere (for example, nitrogen, argon, helium, carbon dioxide, vacuum, hydrogen, etc.) and an oxidizing atmosphere (an atmosphere having an oxygen concentration higher than the air). Medium, carried out at 600-1500 ° C. When sintering is performed in an oxidizing atmosphere, annealing is then performed in a reducing atmosphere. The annealing treatment in the reducing atmosphere performed after sintering in the oxidizing atmosphere is performed in order to cause oxygen deficiency in the oxide sintered body and lower the specific resistance. Accordingly, it is needless to say that the annealing treatment is preferably performed after the sintering when it is desired to further reduce the specific resistance even when the sintering is performed in an air atmosphere or a reducing atmosphere.
In sintering in any atmosphere, the sintering temperature is 600 to 1500 ° C., preferably 1000 to 1300 ° C. If the sintering temperature is less than 600 ° C, the sintering may not proceed sufficiently and the target density may be lowered. On the other hand, if it exceeds 1500 ° C, zinc oxide itself may be decomposed and lost. is there. When the molded body is heated to the sintering temperature, the rate of temperature increase is 5 to 10 ° C./min up to 1000 ° C., and 1 to 4 ° C./min up to 1000 ° C. It is preferable to make the sintered density uniform.

  When sintering in any atmosphere, the sintering time (that is, the holding time at the sintering temperature) is preferably 3 to 15 hours. If the sintering time is less than 3 hours, the sintered density tends to be insufficient, and the strength of the resulting oxide sintered body tends to decrease. On the other hand, if it exceeds 15 hours, the crystal grains of the sintered body As the growth becomes remarkable, there is a tendency that the pores are coarsened and consequently the maximum pore diameter is increased, and as a result, the sintered density may be lowered.

  The method for performing the sintering is not particularly limited. For example, atmospheric pressure firing method, hot press method, hot isostatic pressing method (HIP method), discharge plasma sintering method (SPS method), cold Known methods such as an isotropic pressure method (CIP method), a microwave sintering method, and a millimeter wave sintering method can be employed.

Examples of the reducing atmosphere when performing the annealing treatment include an atmosphere made of at least one selected from the group consisting of nitrogen, argon, helium, carbon dioxide, vacuum, and hydrogen.
As a method for the annealing treatment, for example, a method of heating at normal pressure while introducing a non-oxidizing gas such as nitrogen, argon, helium, carbon dioxide, or hydrogen, or heating under a vacuum (preferably 2 Pa or less). Although it can be performed by a method or the like, the former method at normal pressure is advantageous from the viewpoint of production cost.

  In performing the annealing treatment, the annealing temperature (heating temperature) is preferably 1000 to 1400 ° C., more preferably 1100 to 1300 ° C. The annealing time (heating time) is preferably 7 to 15 hours, and more preferably 8 to 12 hours. If the annealing temperature is less than 1000 ° C., introduction of oxygen deficiency due to the annealing treatment may be insufficient. On the other hand, if it exceeds 1400 ° C., zinc tends to be volatilized, and the composition of the obtained oxide sintered body There is a possibility that (the atomic ratio of Zn and Ti) is different from the desired ratio.

(target)
The target of the present invention is a target used for film formation by sputtering, ion plating, PLD, or EB vapor deposition. In addition, although the solid material used in the film formation may be referred to as “tablet”, in the present invention, these are referred to as “target”.

The target of the present invention is obtained by processing the above-described zinc oxide-based transparent conductive film forming material of the present invention.
A processing method in particular is not restrict | limited, What is necessary is just to employ | adopt a well-known method suitably. For example, the target of the present invention can be obtained by subjecting the transparent conductive film forming material to surface grinding or the like and then cutting it to a predetermined size and then attaching it to a support base. Further, if necessary, a plurality of the transparent conductive film forming materials may be divided into divided shapes to form a large area target (composite target).

  The method for forming a zinc oxide-based transparent conductive film of the present invention is to form a film by a sputtering method, an ion plating method, a PLD method or an EB vapor deposition method. For specific methods and conditions at that time, There is no particular limitation other than the use of the above-described target, and a known sputtering method, ion plating method, PLD method, or EB vapor deposition method and conditions may be appropriately employed.

  The transparent conductive film formed using the zinc oxide-based transparent conductive film forming material or target of the present invention has excellent conductivity and chemical durability (heat resistance, moisture resistance, weather resistance, chemical resistance (alkali resistance, For example, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic paper, and windows of photoelectric conversion elements for solar cells. It is suitably used for applications such as electrodes, electrodes of input devices such as transparent touch panels, and electromagnetic shielding films of electromagnetic shields. Furthermore, the transparent conductive film formed using the zinc oxide-based transparent conductive film forming material or target of the present invention can be used as a transparent radio wave absorber, an ultraviolet absorber, or a transparent semiconductor device as another metal film or metal oxide film. It can also be used in combination.

  The film thickness of the zinc oxide-based transparent conductive film of the present invention may be appropriately set depending on the application and is not particularly limited, but is preferably 50 to 600 nm, more preferably 100 to 500 nm. If the thickness is less than 50 nm, sufficient specific resistance may not be ensured. On the other hand, if the thickness exceeds 600 nm, the film may be colored.

(Transparent conductive substrate)
The transparent conductive substrate of the present invention comprises a zinc oxide-based transparent conductive film formed on a transparent substrate by the above-described method for forming a zinc oxide-based transparent conductive film.
The transparent substrate is not particularly limited as long as the transparent substrate can maintain its shape under film forming conditions by sputtering, ion plating, PLD, or EB vapor deposition. For example, inorganic materials such as various glasses, thermoplastic resins and thermosetting resins (for example, epoxy resin, polymethyl methacrylate, polycarbonate, polystyrene, polyethylene sulfide, polyethersulfone, polyolefin, polyethylene terephthalate, polyethylene naphthalate, triacetyl cellulose) Plate-like material, sheet-like material, film-like material, etc. formed of a resin such as a plastic such as polyimide), and in particular, any of a glass plate, a resin film or a resin sheet Is preferred. The visible light transmittance of the transparent substrate is usually 90% or more, preferably 95% or more.

  In the case where a resin film or a resin sheet is used as the transparent substrate, it is industrially carried out in order to disperse and uniformize damage caused by film formation by sputtering, ion plating, PLD or EB vapor deposition. In the roll-to-roll film forming method, the film is preferably formed in a state where tensile stress is applied while controlling the unwinding speed and the winding speed. Furthermore, the resin film or the resin sheet may be formed in a heated state in advance, or the resin film or the resin sheet may be cooled during the film formation. Also, in order to shorten the time for damage caused by film formation by sputtering, ion plating, PLD or EB vapor deposition, the speed of transporting the resin film or resin sheet is increased (for example, at 1.0 m / min or more). In this case, film formation is possible even if the distance between the target resin film or resin sheet and the target is short, which is advantageous as an industrial process.

  The transparent substrate may be formed with any of a single layer or multiple layers of an insulating layer, a semiconductor layer, a gas barrier layer, or a protective layer as necessary. Examples of the insulating layer include a silicon oxide film and a silicon nitride oxide film. Examples of the semiconductor layer include a thin film transistor (TFT), and the semiconductor layer is mainly formed on a glass substrate. Examples of the gas barrier layer include a silicon oxide film, a silicon nitride oxide film, and a magnesium aluminate film, and the gas barrier layer is formed on a resin plate or a resin film as a water vapor barrier film. A protective layer is for protecting the surface of a base material from a damage | wound and an impact, and various coating layers, such as Si type | system | group, Ti type | system | group, and an acrylic resin type | system | group, are mentioned.

The specific resistance of the transparent conductive substrate of the present invention is usually 2 × 10 ⁻³ Ω · cm or less, preferably 8 × 10 ⁻⁴ Ω · cm or less. The surface resistance (sheet resistance) varies depending on the application, but is usually 5 to 10,000 Ω / □, preferably 10 to 300 Ω / □. In addition, specific resistance and surface resistance can be measured by the method mentioned later in an Example, for example.
The transmittance of the transparent conductive substrate of the present invention is usually 85% or more, preferably 90% or more in the visible light region. The total light transmittance is preferably 80% or more, more preferably 85% or more, and the haze value is preferably 10% or less, more preferably 5% or less. The transmittance can be measured by, for example, a method described later in the examples.

The thickness of the zinc oxide-based transparent conductive film in the transparent conductive substrate of the present invention is preferably 50 to 600 nm. In this film thickness range, although it varies depending on the application, it is possible to obtain a continuous film in which flexibility is maintained. Furthermore, the film thickness of the transparent conductive film of the present invention is desirably 100 to 500 nm depending on the application.
In the transparent conductive substrate of the present invention, if necessary, as an outermost layer, any resin that functions as a protective film, an antireflection film, a filter, etc., functions of adjusting the viewing angle of liquid crystal, preventing fogging, etc. Alternatively, one layer or two or more layers of inorganic compounds can be stacked.

  The transparent conductive substrate of the present invention has good transparency as described above, and excellent conductivity and chemical durability (heat resistance, moisture resistance, weather resistance, chemical resistance as described above). (Alkali resistance, acid resistance, etc.)). Therefore, for example, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, and electronic papers, window electrodes of photoelectric conversion elements of solar cells, electrodes of input devices such as transparent touch panels, electromagnetic It can be used in combination with other metal film / metal oxide film as an electromagnetic shielding film of a shield, a transparent radio wave absorber, an ultraviolet absorber, and a transparent semiconductor device.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.
In addition, evaluation of the obtained transparent conductive substrate was performed by the following method.

<Resistivity>
The specific resistance was measured by a four-terminal four-probe method using a resistivity meter (“LORESTA-GP, MCP-T610” manufactured by Mitsubishi Chemical Corporation). Specifically, four needle-shaped electrodes are placed on a straight line on the sample, a constant current is passed between the outer two probes, a constant current is passed between the inner two probes, and the inner two probes are The resulting potential difference was measured to determine the resistance.
<Surface resistance>
The surface resistance (Ω / □) was calculated by dividing the specific resistance (Ω · cm) by the film thickness (cm).
<Transmissivity>
The transmittance was measured using an ultraviolet visible near infrared spectrophotometer (“V-670” manufactured by JASCO Corporation).
<Moisture resistance>
The transparent conductive substrate was subjected to a moisture resistance test in which the transparent conductive substrate was held in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90% for 1000 hours, and then the surface resistance was measured. It can be said that the surface resistance after the moisture resistance test is excellent in moisture resistance when the surface resistance before the moisture resistance test is twice or less.
<Heat resistance>
The transparent conductive substrate was subjected to a heat resistance test in which the transparent conductive substrate was held in the atmosphere at a temperature of 200 ° C. for 5 hours, and then the surface resistance was measured. When the surface resistance after the heat test is 1.5 times or less than the surface resistance before the heat test, it can be said that the heat resistance is excellent.
<Alkali resistance>
The transparent conductive substrate was immersed in a 3% NaOH aqueous solution (40 ° C.) for 10 minutes, and the presence or absence of a change in film quality on the substrate before and after immersion was confirmed visually.
<Acid resistance>
The transparent conductive substrate was immersed in a 3% aqueous HCl solution (40 ° C.) for 10 minutes, and the presence or absence of a change in film quality on the substrate before and after immersion was confirmed visually.

[Example 1]
Zinc oxide (ZnO, manufactured by Kishida Chemical Co., Ltd.), gallium fluoride (GaF ₃ , manufactured by Wako Pure Chemical Industries, Ltd.), and titanium oxide (Ti ₂ O ₃ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) The zinc element, the titanium element, and the gallium element are weighed so as to have an atomic ratio of Zn: Ti: Ga = 96.5: 3.0: 0.5, placed in a polypropylene container, and further a 2 mmφ zirconia ball. And ethanol as a mixed solvent. This was mixed by a ball mill to obtain a raw material powder.
After the mixing operation, the 2 mmφ zirconia balls and the raw material powder obtained by removing ethanol were placed in a mold and pressurized with a pressure of 40 MPa to obtain a disk-shaped molded body. This was put in an electric furnace and heat-treated at 1100 ° C. in an Ar atmosphere to obtain an oxide sintered body. It was 93.8% when the relative density of this oxide sintered compact was computed from the size of the oxide sintered compact. The relative density is obtained by multiplying the unit density of zinc oxide, gallium fluoride, and titanium oxide by the weight ratio of the mixture, and taking the sum as a theoretical density of 100% (the following formulas (A) and (B) reference). The obtained oxide sintered body was ground and polished to obtain an oxide sintered body having a diameter of 50.8 mmφ and a thickness of 3 mm.
Relative density = 100 × [(density of sintered body) / (theoretical density)] (A)
Theoretical density = (Zinc oxide single density × mixing weight ratio + gallium fluoride single density × mixing weight ratio + titanium oxide single density × mixing weight ratio) (B)

The obtained oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target.
Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 500 nm was obtained.
Target size: 50.8 mmφ × 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 30W
Substrate used: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

The obtained thin film was dissolved in 2-fold diluted hydrochloric acid, and the thin film composition was measured by ICP-AES (“Thermo-6500” manufactured by Thermo Scientific). The molar ratio of zinc: titanium: gallium was determined by the target composition. A thin film having almost the same composition as the above was obtained. Whether or not fluorine is contained in the thin film was examined by XPS (X-ray photoelectron spectroscopy, “VG Theta Prob” manufactured by Thermo Fisher Scientific Co., Ltd.), and it was confirmed that fluorine was contained in the thin film. .
The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). It was also found that gallium was substituted and dissolved in zinc.
The sheet resistance of the obtained thin film was measured using a four-probe method (Mitsubishi Chemical Co., Ltd., Loresta), and the film thickness was measured using "Alpha-Step IQ" manufactured by KLA-Tencor Co., Ltd., and the resistivity was calculated. As a result, it was 3.7 × 10 ⁻⁴ Ω · cm. The surface resistance was 7.4Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane. Further, when hole measurement (“HL5500” manufactured by Nanometrics Japan Co., Ltd.) was performed, the carrier concentration was 1.04 × 10 ²¹ cm ⁻³ and the carrier electron mobility was 15.4 cm ² / V · s. .
The transmittance of the transparent conductive substrate obtained was 89% on average in the visible region (380 nm to 780 nm) and 89% on average in the near infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the near infrared region (780 nm to 1500 nm) was 94% on average. It can be seen that the resistance is reduced while the transmittance in the near infrared region is high.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 1.2 times the surface resistance before the moisture resistance test, and the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 1.2 times the surface resistance before the heat test, and it was found that the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

From the above, the film on the obtained transparent conductive substrate is a transparent conductive film that is transparent and has low resistance, and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is. Moreover, since it is excellent in alkali resistance and acid resistance, it is estimated that it has an appropriate etching rate at the time of patterning.
Furthermore, by doping with fluorine, the carrier electron mobility can be increased, and the obtained film on the transparent conductive substrate can be further reduced in resistance without impairing the transmittance in the near infrared region. did it.

[Example 2]
Zinc oxide (ZnO, manufactured by Kishida Chemical Co., Ltd.), aluminum fluoride (AlF ₃ , manufactured by Wako Pure Chemical Industries, Ltd.), and titanium oxide (Ti ₂ O ₃ , manufactured by Kojundo Chemical Laboratory Co., Ltd.) The zinc element, the titanium element, and the aluminum element are weighed so as to have an atomic ratio of Zn: Ti: Al = 96.5: 3.0: 0.5, placed in a polypropylene container, and further a 2 mmφ zirconia ball. And ethanol as a mixed solvent. This was mixed by a ball mill to obtain a raw material powder.
After the mixing operation, the 2 mmφ zirconia balls and the raw material powder obtained by removing ethanol were placed in a mold and pressurized with a pressure of 40 MPa to obtain a disk-shaped molded body. This was put in an electric furnace and heat-treated at 1100 ° C. in an Ar atmosphere to obtain an oxide sintered body. It was 93.5% when the relative density of this oxide sintered compact was computed from the size of the oxide sintered compact. The relative density is obtained by multiplying the unit density of zinc oxide, aluminum fluoride, and titanium oxide by the weight ratio of mixing, and taking the sum as 100% (see formula (A) and formula (C) below). ). The obtained oxide sintered body was ground and polished to obtain an oxide sintered body having a diameter of 50.8 mmφ and a thickness of 3 mm.
Theoretical density = (Zinc oxide simple substance density × mixing weight ratio + Aluminum fluoride simple substance density × mixing weight ratio + Titanium oxide simple substance density × mixing weight ratio) (C)

The obtained oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target.
Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 500 nm was obtained.
Target size: 50.8 mmφ × 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 30W
Substrate used: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

The obtained thin film was dissolved in 2-fold diluted hydrochloric acid, and the thin film composition was measured by ICP-AES (“Thermo-6500” manufactured by Thermo Scientific). The molar ratio of zinc: titanium: aluminum was determined by the target composition. A thin film having almost the same composition as the above was obtained. Whether or not fluorine is contained in the thin film was examined by XPS (X-ray photoelectron spectroscopy, manufactured by Thermo Fisher Scientific Co., Ltd., “VG Theta Probe”), it was confirmed that fluorine was contained in the thin film. It was.
The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). It was also found that aluminum was substituted and dissolved in zinc.
The sheet resistance of the obtained thin film was measured using a four-probe method (Mitsubishi Chemical Co., Ltd., Loresta), and the film thickness was measured using "Alpha-Step IQ" manufactured by KLA-Tencor Co., Ltd., and the resistivity was calculated. As a result, it was 3.8 × 10 ⁻⁴ Ω · cm. The surface resistance was 7.6Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane. Further, when hole measurement (“HL5500” manufactured by Nanometrics Japan Co., Ltd.) was performed, the carrier concentration was 1.02 × 10 ²¹ cm ⁻³ and the carrier electron mobility was 15.1 cm ² / V · s. .
The transmittance of the transparent conductive substrate obtained was 89% on average in the visible region (380 nm to 780 nm) and 89% on average in the near infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the near infrared region (780 nm to 1500 nm) was 94% on average. It can be seen that the resistance is reduced while the transmittance in the near infrared region is high.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 1.2 times the surface resistance before the moisture resistance test, and the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 1.2 times the surface resistance before the heat test, and it was found that the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

From the above, the film on the obtained transparent conductive substrate is a transparent conductive film that is transparent and has low resistance, and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is. Moreover, since it is excellent in alkali resistance and acid resistance, it is estimated that it has an appropriate etching rate at the time of patterning.
Furthermore, by doping with fluorine, the carrier electron mobility can be increased, and the obtained film on the transparent conductive substrate can be further reduced in resistance without impairing the transmittance in the near infrared region. did it.

[Example 3]
Zinc oxide (ZnO, manufactured by Kishida Chemical Co., Ltd.), aluminum fluoride (AlF ₃ , manufactured by Wako Pure Chemical Industries, Ltd.), and titanium (II) oxide (TiO, manufactured by Kojundo Chemical Laboratory Co., Ltd.) The zinc element, the titanium element, and the aluminum element are weighed so as to have an atomic ratio of Zn: Ti: Al = 96.5: 3.0: 0.5, placed in a polypropylene container, and further a 2 mmφ zirconia ball. And ethanol as a mixed solvent. This was mixed by a ball mill to obtain a raw material powder.
After the mixing operation, the 2 mmφ zirconia balls and the raw material powder obtained by removing ethanol were placed in a mold and pressurized with a pressure of 40 MPa to obtain a disk-shaped molded body. This was put in an electric furnace and heat-treated at 1100 ° C. in an Ar atmosphere to obtain an oxide sintered body. It was 93.5% when the relative density of this oxide sintered compact was computed from the size of the oxide sintered compact. The relative density is obtained in the same manner as in Example 2. The obtained oxide sintered body was ground and polished to obtain an oxide sintered body having a diameter of 50.8 mmφ and a thickness of 3 mm.

The obtained oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target.
Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 500 nm was obtained.
Target size: 50.8 mmφ × 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 30W
Substrate used: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

The obtained thin film was dissolved in 2-fold diluted hydrochloric acid, and the thin film composition was measured by ICP-AES (“Thermo-6500” manufactured by Thermo Scientific). The molar ratio of zinc: titanium: aluminum was determined by the target composition. A thin film having almost the same composition as the above was obtained. Whether or not fluorine is contained in the thin film was examined by XPS (X-ray photoelectron spectroscopy, “VG Theta Probe” manufactured by Thermo Fisher Scientific Co., Ltd.), and it was confirmed that fluorine was contained in the thin film. .
The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). It was also found that aluminum was substituted and dissolved in zinc.
The sheet resistance of the obtained thin film was measured using a four-probe method (Mitsubishi Chemical Co., Ltd., Loresta), and the film thickness was measured using "Alpha-Step IQ" manufactured by KLA-Tencor Co., Ltd., and the resistivity was calculated. As a result, it was 3.6 × 10 ⁻⁴ Ω · cm. The surface resistance was 7.2Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane. In addition, when hole measurement (“HL5500” manufactured by Nanometrics Japan Co., Ltd.) was performed, the carrier concentration was 1.08 × 10 ²¹ cm ⁻³ and the carrier electron mobility was 15.4 cm ² / V · s. .
The transmittance of the transparent conductive substrate obtained was 89% on average in the visible region (380 nm to 780 nm) and 89% on average in the near infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the near infrared region (780 nm to 1500 nm) was 94% on average. It can be seen that the resistance is reduced while the transmittance in the near infrared region is high.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 1.2 times the surface resistance before the moisture resistance test, and the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 1.2 times the surface resistance before the heat test, and it was found that the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

From the above, the film on the obtained transparent conductive substrate is a transparent conductive film that is transparent and has low resistance, and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is. Moreover, since it is excellent in alkali resistance and acid resistance, it is estimated that it has an appropriate etching rate at the time of patterning.
Furthermore, by doping with fluorine, the carrier electron mobility can be increased, and the obtained film on the transparent conductive substrate can be further reduced in resistance without impairing the transmittance in the near infrared region. did it.

Example 4
Zinc oxide (ZnO, manufactured by Kishida Chemical Co., Ltd.), aluminum fluoride (AlF ₃ , manufactured by Wako Pure Chemical Industries, Ltd.), and titanium (II) oxide (TiO, manufactured by Kojundo Chemical Laboratory Co., Ltd.) The zinc element, the titanium element and the aluminum element are weighed so that the atomic ratio of Zn: Ti: Al = 93.9: 2.1: 4.0 is placed in a polypropylene container, and further a 2 mmφ zirconia ball. And ethanol as a mixed solvent. This was mixed by a ball mill to obtain a raw material powder.
After the mixing operation, the 2 mmφ zirconia balls and the raw material powder obtained by removing ethanol were placed in a mold and pressurized with a pressure of 40 MPa to obtain a disk-shaped molded body. This was put in an electric furnace and heat-treated at 1100 ° C. in an Ar atmosphere to obtain an oxide sintered body. It was 93.1% when the relative density of this oxide sintered compact was computed from the size of the oxide sintered compact. The relative density is obtained in the same manner as in Example 2. The obtained oxide sintered body was ground and polished to obtain an oxide sintered body having a diameter of 50.8 mmφ and a thickness of 3 mm.

The obtained oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target.
Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 500 nm was obtained.
Target size: 50.8 mmφ × 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 30W
Substrate used: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

The obtained thin film was dissolved in 2-fold diluted hydrochloric acid, and the thin film composition was measured by ICP-AES (“Thermo-6500” manufactured by Thermo Scientific). The molar ratio of zinc: titanium: aluminum was determined by the target composition. A thin film having almost the same composition as the above was obtained. Whether or not fluorine is contained in the thin film was examined by XPS (X-ray photoelectron spectroscopy, “VG Theta Probe” manufactured by Thermo Fisher Scientific Co., Ltd.), and it was confirmed that fluorine was contained in the thin film. .
The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). It was also found that aluminum was substituted and dissolved in zinc.
The sheet resistance of the obtained thin film was measured using a four-probe method (Mitsubishi Chemical Co., Ltd., Loresta), and the film thickness was measured using "Alpha-Step IQ" manufactured by KLA-Tencor Co., Ltd., and the resistivity was calculated. As a result, it was 3.8 × 10 ⁻⁴ Ω · cm. The surface resistance was 7.6Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane. Further, when hole measurement (“HL5500” manufactured by Nanometrics Japan Co., Ltd.) was performed, the carrier concentration was 1.08 × 10 ²¹ cm ⁻³ and the carrier electron mobility was 14.4 cm ² / V · s. .
The transmittance of the transparent conductive substrate obtained was 89% on average in the visible region (380 nm to 780 nm) and 89% on average in the near infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the near infrared region (780 nm to 1500 nm) was 94% on average. It can be seen that the resistance is reduced while the transmittance in the near infrared region is high.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the moisture resistance test was 1.4 times the surface resistance before the moisture resistance test, and it was found that the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 1.4 times the surface resistance before the heat test, and it was found that the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

From the above, the film on the obtained transparent conductive substrate is a transparent conductive film that is transparent and has low resistance, and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is. Moreover, since it is excellent in alkali resistance and acid resistance, it is estimated that it has an appropriate etching rate at the time of patterning.
Furthermore, by doping with fluorine, the carrier electron mobility can be increased, and the obtained film on the transparent conductive substrate can be further reduced in resistance without impairing the transmittance in the near infrared region. did it.

(Example 5)
Zinc oxide (ZnO, manufactured by Kishida Chemical Co., Ltd.), aluminum fluoride (AlF ₃ , manufactured by Wako Pure Chemical Industries, Ltd.), and titanium (II) oxide (TiO, manufactured by Kojundo Chemical Laboratory Co., Ltd.) The zinc element, the titanium element, and the aluminum element were weighed so that the atomic ratio of Zn: Ti: Al = 95.0: 3.0: 2.0, placed in a polypropylene container, and then a 2 mmφ zirconia ball. And ethanol as a mixed solvent. This was mixed by a ball mill to obtain a raw material powder.
After the mixing operation, the 2 mmφ zirconia balls and the raw material powder obtained by removing ethanol were placed in a mold and pressurized with a pressure of 40 MPa to obtain a disk-shaped molded body. This was put in an electric furnace and heat-treated at 1100 ° C. in an Ar atmosphere to obtain an oxide sintered body. It was 93.1% when the relative density of this oxide sintered compact was computed from the size of the oxide sintered compact. The relative density is obtained in the same manner as in Example 2. The obtained oxide sintered body was ground and polished to obtain an oxide sintered body having a diameter of 50.8 mmφ and a thickness of 3 mm.

The obtained oxide sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target.
Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 500 nm was obtained.
Target size: 50.8 mmφ × 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 30W
Substrate used: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

The obtained thin film was dissolved in 2-fold diluted hydrochloric acid, and the thin film composition was measured by ICP-AES (“Thermo-6500” manufactured by Thermo Scientific). The molar ratio of zinc: titanium: aluminum was determined by the target composition. A thin film having almost the same composition as the above was obtained. Whether or not fluorine is contained in the thin film was examined by XPS (X-ray photoelectron spectroscopy, “VG Theta Probe” manufactured by Thermo Fisher Scientific Co., Ltd.), and it was confirmed that fluorine was contained in the thin film. .
The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). It was also found that aluminum was substituted and dissolved in zinc.
The sheet resistance of the obtained thin film was measured using a four-probe method (Mitsubishi Chemical Co., Ltd., Loresta), and the film thickness was measured using "Alpha-Step IQ" manufactured by KLA-Tencor Co., Ltd., and the resistivity was calculated. As a result, it was 3.6 × 10 ⁻⁴ Ω · cm. The surface resistance was 7.2Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane. Further, when hole measurement (“HL5500” manufactured by Nanometrics Japan Co., Ltd.) was performed, the carrier concentration was 1.10 × 10 ²¹ cm ⁻³ and the carrier electron mobility was 15.3 cm ² / V · s. .
The transmittance of the transparent conductive substrate obtained was 89% on average in the visible region (380 nm to 780 nm) and 89% on average in the near infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the near infrared region (780 nm to 1500 nm) was 94% on average. It can be seen that the resistance is reduced while the transmittance in the near infrared region is high.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 1.2 times the surface resistance before the moisture resistance test, and the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 1.2 times the surface resistance before the heat test, and it was found that the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

From the above, the film on the obtained transparent conductive substrate is a transparent conductive film that is transparent and has low resistance, and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is. Moreover, since it is excellent in alkali resistance and acid resistance, it is estimated that it has an appropriate etching rate at the time of patterning.
Furthermore, by doping with fluorine, the carrier electron mobility can be increased, and the obtained film on the transparent conductive substrate can be further reduced in resistance without impairing the transmittance in the near infrared region. did it.

Claims (5)

A zinc oxide-based transparent conductive film forming material containing zinc oxide as a main component, including at least one of gallium fluoride and aluminum fluoride, and further including titanium,
The ratio of the number of titanium atoms to the total number of metal atoms is more than 2% and not more than 10%, and the ratio of the number of metal atoms of one or both of gallium fluoride and aluminum fluoride to the total number of metal atoms is 0.1% or more and 5 %, And as a titanium source, it is an oxide sintered body using a low-valence titanium oxide represented by the general formula: TiO _2-X (X = 0.1-1). Zinc oxide-based transparent conductive film forming material.   The zinc oxide-based transparent conductive film forming material according to claim 1, wherein a relative density of the oxide sintered body is 93% or more.   3. The zinc oxide-based transparent conductive film forming material according to claim 1, which is a target used for film formation by a sputtering method, an ion plating method, a pulse laser deposition (PLD) method, or an electron beam (EB) evaporation method. Target characterized by processing.   A zinc oxide-based transparent conductive film is formed by sputtering, ion plating, pulsed laser deposition (PLD), or electron beam (EB) evaporation using the target according to claim 3. A method of forming a zinc oxide-based transparent conductive film.   A transparent conductive substrate comprising a zinc oxide-based transparent conductive film formed on the transparent substrate by the method for forming a zinc oxide-based transparent conductive film according to claim 4.