JP2019003900A - Transparent conductive film, transparent substrate with transparent conductive film, method for producing transparent substrate with transparent conductive film, and touch panel - Google Patents

Abstract

To provide a novel transparent conductive film using an indium oxide material with a low resistivity and a high visible light transmittance.SOLUTION: A transparent conductive film is an oxide material composed of indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum.SELECTED DRAWING: None

Description

  The present disclosure relates to a transparent conductive film, a transparent substrate with a transparent conductive film, a method for manufacturing a transparent substrate with a transparent conductive film, and a touch panel.

  Conventionally, a material having high conductivity (low resistivity) and high light transmittance in the visible light region has been used for the transparent conductive film. As a material having high conductivity and high light transmittance in the visible light region, an oxide-based material is used. As the oxide material, for example, an indium oxide-based material containing indium oxide as a main component is known. A transparent conductive film made of an indium oxide-based material is typically applied as a touch panel sensor, for example.

  In order to apply the transparent conductive film to, for example, the field of touch panel sensors, it is required to simultaneously improve two conflicting factors of resistivity reduction and light transmittance improvement. As a material for satisfying this requirement, for example, indium doped with tin (ITO: Indium Tin Oxide) is well known.

  ITO uses the fact that tin (Sn) takes a tetravalent ionic state, and replaces Sn with a part of the indium (In) site that becomes a trivalent ionic state, thereby generating surplus charges. To lower the resistance. The band gap of indium oxide is about 3.55 eV, and the band gap of tin oxide is 3.57 eV. Therefore, ITO can realize higher light transmittance than indium oxide alone by adding tin oxide to indium oxide.

  Based on such a concept, for example, a transparent conductive film in which indium oxide is doped with silicon oxide is disclosed (see Patent Documents 1 and 2).

For example, Patent Document 1 discloses a transparent conductive thin film containing indium oxide as a main component and containing silicon. And it is disclosed that the structure of the transparent conductive thin film is substantially amorphous, and the silicon content is 0.5 atomic% to 13 atomic% with respect to the total amount of indium and silicon. Yes.
Patent Document 2 discloses an oxide sintered body in which silicon element is solid-solved in indium oxide in an oxide sintered body containing indium and silicon.

  In addition to the above, as the oxide-based material used for the transparent conductive film, for example, the following materials are known (see Patent Documents 3 to 5).

Patent Document 3 discloses a transparent conductive film formed on a substrate by a sputtering method. The transparent conductive film includes a first component made of indium oxide, a second component made of tin oxide, lanthanum, neodymium, dysprosium, europium, gadolinium, terbium, zirconium, aluminum, silicon, titanium, and boron. And a third component comprising at least one element selected from the above or an oxide thereof.
Patent Document 4 discloses a zinc oxide-based transparent conductive film having irregularities formed on the surface. And this unevenness | corrugation is an obtuse angle whose ridgeline part draws an arc in the protrusion direction of a protrusion part, or when the front-end | tip of a protrusion part has a vertex, the angle which two ridgeline parts make centering on this vertex It is disclosed that the protrusion part is included. Furthermore, it is disclosed that this zinc oxide-based conductive film has at least one selected from the group consisting of aluminum, gallium, boron or silicon as a dopant.

Patent Document 5 discloses an oxide transparent electrode film made of indium oxide containing titanium and formed on a substrate heated to 150 ° C. or higher and 350 ° C. or lower. This oxide transparent electrode film discloses that indium in indium oxide is substituted with titanium at a ratio of 0.003 to 0.120 in terms of the number ratio of titanium / indium. Further, the indium oxide is crystalline, the specific resistance of the oxide transparent electrode film is 5.7 × 10 ⁻⁴ Ωcm or less, and the carrier electron concentration by the hole measurement effect is 5.5 × 10 ²⁰ cm ^{−. 3} or less, the mobility of carrier electrons by Hall effect measurement is 40 cm ² / Vsec or more, and the average light transmittance at wavelengths of 1000 nm to 1400 nm is disclosed to be 60% or more.

  On the other hand, in recent years, substitution of Si in indium materials mainly containing indium and containing indium and silicon shortens the bond distance between indium atoms and oxygen atoms, and increases the overlap of indium 5s orbitals to facilitate carrier conduction. It has been reported that it is interpreted as having a role to play (see Non-Patent Document 1).

JP 2004-087451 A JP 2004-123479 A JP2015-158014A Special table 2012-504306 gazette Japanese Patent No. 5234023

Phase transitions from semiconductive amorphous to conductive polycrystalline in indium silicon oxide thin films, Nobuhiko Mitoma, Bo Da, Hideki Yoshikawa, Toshihide Nabatame, Makoto Takahashi, Kazuhiro Ito, Takio Kizu, Akihiko Fujiwara, and Kazuhito Tsukagoshi, Appl. Phys. Lett. 109, 221903 (2016)

  An object of the present disclosure is to provide a transparent conductive film, a transparent substrate with a transparent conductive film, a method for producing a transparent substrate with a transparent conductive film, using a novel indium oxide-based material with low resistivity and high light transmittance in visible light, It is to provide a touch panel.

Means for solving the above problems include the following aspects.
<1> A transparent conductive film that is an oxide material made of indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum.
<2> The transparent conductive film according to <1>, wherein the content of the element is 0.1 atomic% or more and 25 atomic% or less with respect to the entire oxide material.
<3> The transparent conductive film according to <1> or <2>, wherein the oxide material is amorphous.
<4> The transparent conductive film according to any one of <1> to <3>, wherein the element is boron.
The transparent substrate with a transparent conductive film which has a <5> transparent substrate and the transparent conductive film as described in any one of <1>-<4> on the said transparent substrate.
<6> The transparent substrate with a transparent conductive film according to <5>, wherein the transparent conductive film is a transparent conductive film formed in a pattern.
<7> Transparent with transparent conductive film having a transparent conductive film forming step of forming a transparent conductive film according to any one of <1> to <4>, using indium oxide containing boron as a target on a transparent substrate A method for manufacturing a substrate.
<8> The method for producing a transparent substrate with a transparent conductive film according to <7>, further comprising a pattern forming step of forming a pattern on the transparent conductive film.
<9> A touch panel comprising the transparent substrate with a transparent conductive film according to <5> or <6>.

  According to the transparent conductive film of the present disclosure, a transparent conductive film, a transparent substrate with a transparent conductive film, and a transparent substrate with a transparent conductive film using a novel indium oxide-based material with low resistivity and high light transmittance in visible light A manufacturing method and a touch panel are provided.

It is a schematic sectional drawing which shows an example of the touchscreen of this indication. It is a graph showing the light transmittance in the visible region of a transparent conductive film. It is a graph showing the X-ray-diffraction spectrum of a transparent conductive film. It is a graph showing the measurement result of the patterned transparent conductive film cross section in the transparent substrate with the patterned transparent conductive film of this indication. It is a graph showing the measurement result of the patterned transparent conductive film cross section in the conventional transparent substrate with a patterned transparent conductive film.

  Below, an example of suitable embodiment of the transparent conductive film of this indication is demonstrated.

<Transparent conductive film>
The transparent conductive film of the present disclosure is formed of an oxide material made of indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum.
This oxide material is formed as a composite oxide material composed of an indium oxide-based material in which indium oxide as a base material is doped with an oxide of at least one element selected from the group consisting of boron, magnesium, and aluminum. It is a thing. That is, the transparent conductive film of the present disclosure may be formed by doping indium oxide as a base material with one oxide of boron oxide, magnesium oxide, and aluminum oxide. It may be formed by using a combination of more than one kind of oxides.

  As described above, conventionally, various materials have been studied as oxide materials used for the oxide conductive film. For example, the following materials are known as oxide materials that may be doped with boron.

  For example, Patent Document 3 discloses a transparent conductive film doped with a specific element or an oxide of a specific element as a third element doped into ITO. However, in a transparent conductive film using an indium oxide-based material, as described above, the indium 5s orbital is responsible for forming a conduction path. Therefore, when boron is selected as the third element, it is considered that multiple types of ion doping due to the coexistence of tin and boron cause a decrease in conductivity due to ion scattering. In addition, it is known that doping with boron alone results in an oxygen deficient excess in the composition of the thin film after film formation. Therefore, when doped with boron alone as the third element, a thin film having the desired composition may not be obtained on the substrate after film formation.

  Patent Document 4 discloses a transparent conductive film using a zinc oxide-based material doped with at least one element of aluminum, gallium, boron, and silicon using zinc oxide as a base material. However, referring to zinc oxide, which is a base material, the electrical conductivity is significantly lowered by heat treatment in an air atmosphere, and the required performance as a transparent conductive film may not be satisfied.

  On the other hand, in order to improve various performances as a transparent conductive film, there is a report that it is desirable to crystallize the transparent conductive film by, for example, heat treatment or heating film formation (see Patent Document 5). However, a film already crystallized at the time of film formation may be difficult to etch with a conventional oxalic acid-based weak acid etchant, for example, when patterning is performed by etching. For this reason, it is desirable that the transparent conductive film can be formed in an amorphous state that can be etched with a weak acid etchant and is not crystallized immediately after the film formation. If the transparent conductive film can be applied with a conventional etching process, it is considered that the application of the transparent conductive film can be easily applied to, for example, a touch panel sensor and a conventional etching application such as a display thin film transistor. .

Thus, there has been a demand for the development of an excellent indium oxide-based material that can obtain high conductivity (low resistivity) and high light transmittance in visible light only by adding to indium oxide.
On the other hand, according to the transparent conductive film of the present disclosure, a transparent conductive film showing a low resistivity and a high light transmittance with visible light can be obtained.

As a dopant for indium oxide, a bond distance between oxygen atoms that can exist stably in the atmosphere as a solid oxide state, and can maximize the carrier conduction path by increasing the overlap of the indium 5s orbitals. It is desirable to contain short elements.
Then, the dopant to indium oxide was examined.

Such a dopant is selected from oxides of elements that satisfy the following conditions in order to obtain an indium oxide-based material having a low resistivity and a high visible light transmittance.
1) An oxide solid that can exist stably in the atmosphere.
2) The bond distance between the dopant element and oxygen is shorter than the bond distance between indium and oxygen (1.902 mm).
3) The material is larger than the band gap (3.57 eV) of tin oxide.
4) The dopant material has 6 coordination and is higher than the oxygen bond dissociation energy (346 kJ / mol) of indium and oxygen.

  Table 1 shows oxides of suitable elements among the elements satisfying the above conditions 1) to 4). Note that the oxides of Si and Ti are oxides conventionally applied as dopants for indium oxide.

  Among the elements shown in Table 1, boron is particularly preferable. That is, as the dopant for indium oxide, a boron oxide having the shortest bond distance among the oxides shown in Table 1 is more preferable. If the dopant is an oxide of boron, the overlap of the indium 5s orbitals can be further increased, so that it is considered that both the characteristics of resistivity and visible light transmittance can be improved.

Here, the cell parameters were examined for a boron oxide particularly suitable as a dopant for indium oxide. The result of investigating the cell parameters of the unit cell in each oxide material of indium oxide and indium oxide containing boron (hereinafter sometimes referred to as “boron-doped indium oxide”) is shown.
As the boron-doped indium oxide, an In (BO ₃ ) unit cell was investigated in order to pay attention to lattice distortion.
As a result of the investigation, in the unit cell of indium oxide, the cell parameter was 0.5487 nm for both the a side and the b side. On the other hand, in boron-doped indium oxide, the cell parameter was 0.48217 nm for both the a side and the b side. From this result, it became clear that boron-doped indium oxide can increase the overlap of the indium 5s orbitals.
Therefore, according to the transparent conductive film of this indication, it is thought that the transparent conductive film which shows the low light resistivity and the high light transmittance in visible light is obtained.

The cell parameters of indium oxide and boron-doped indium oxide were investigated using a crystal structure database. Specifically, in the In (BO _3), structure type: Ca _(CO 3), Pearson symbol: HR30, space group: rhombohedral In being unique identification in R-3c of (BO ₃₎ crystal structure Data was used. In the _In 2 _{O 3,} structure type: _Al 2 _{O 3,} Pearson symbol: HR30, space group: using crystal structure data of rhombohedral _In 2 _{O 3,} which is unique identification in R-3c.

  In the transparent conductive film of the present disclosure, the content of at least one element selected from the group consisting of boron, magnesium, and aluminum is 0.1 atomic percent or more and 25 atomic percent or less with respect to the entire oxide material. It is good. For example, when the oxide material is an oxide material of indium oxide containing magnesium (magnesium-doped indium oxide), the magnesium content is 0.1 atomic% or more and 22.2% with respect to the entire magnesium-doped indium oxide. It is preferably at most atomic%. For example, when the oxide material is indium oxide containing aluminum or an indium oxide oxide material containing boron, the entire oxide material of indium oxide containing aluminum or indium oxide containing boron is used. It is preferable that they are 0.1 atomic% or more and 20 atomic% or less.

  In particular, when the oxide material is, for example, an oxide material of indium oxide containing boron (boron-doped indium oxide), the boron content is 0.5 atomic% or more and 15 to 15% with respect to the whole boron-doped indium oxide. Atomic% or less is more preferable, and 1 atomic% or more and 10 atomic% or less is more preferable.

Here, the element content is the content in the sputter target sintered body.
The element content is calculated from the mass ratio of each material in the sputtering target. The element content is converted as follows.

About conversion to atomic%, it can calculate using the mass% ratio and molecular weight of each powder at the time of sintered compact formation. As an example, boron-doped indium oxide will be described as an example.
As the mass% ratio of the powder at the time of the sintered body formation, _{an In} 2 _{O 3} is 95 _wt%, an In of InBO _x sintered body in the case B 2 _{O 3} is 5% by mass, B, each atom% of O is Estimated as follows.

In ₂ O ₃ in the In of the mol number = _In 2 _{O 3} mass% ÷ _In 2 _{O 3} molecular weight × _In 2 _{O 3} in the In atom number = 95 ÷ 277.6 × 2 = 0.684
In ₂ O ₃ in the O of mol number = _In 2 _{O 3} mass% ÷ _In 2 _{O 3} molecular weight × _In 2 _{O 3} in the O of atoms = 95 ÷ 277.6 × 3 = 1.027
B ₂ O ₃ in mol number of B ₌ B 2 _{O 3} mass% ÷ _B 2 _{O 3} molecular weight × _B 2 _{O 3} in the number of atoms of B = 5 ÷ 69.6 × 2 = 0.144
B ₂ O ₃ in the O of mol number ₌ B 2 _{O 3} mass% ÷ _B 2 _{O 3} molecular weight × _B 2 _{O 3} in the O of atoms = 5 ÷ 69.6 × 3 = 0.215
InBO _x In atomic percentage of InBO _x sintered body = In mole number ÷ (In mole number + B mole number + O mole number) × 100 = 0.684 ÷ (0.684 + 0.144 + 1.242) × 100 = 33 .1
Atomic% of B in InBO _x sintered body = number of moles of B ÷ (number of moles of In + number of moles of B + number of moles of O) × 100 = 0.144 ÷ (0.684 + 0.144 + 1.242) × 100 = 6 .9
Atomic% of O in InBO _x sintered body = number of moles of O ÷ (number of moles of In + number of moles of B + number of moles of O) × 100 = 1.242 ÷ (0.684 + 0.144 + 1.242) × 100 = 60 .0

In addition, as described above, the transparent conductive film of the present disclosure is an oxide obtained by adding an oxide of at least one element selected from the group consisting of boron, magnesium, and aluminum as a dopant to indium oxide. Material. By using such an oxide material, local crystallization of indium oxide at the time of forming the transparent conductive film can be suppressed. Therefore, indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum tends to be amorphous. Moreover, as a result, the transparent conductive film of this indication becomes easy to form the transparent conductive film near the homogeneity excellent in the flatness of the film | membrane surface.
Note that the transparent conductive film of the present disclosure can be crystallized by heat treatment. What is necessary is just to determine the heat processing conditions for crystallization according to the degree of the target crystallization, for example.

  As a method for confirming that the transparent conductive film is amorphous, for example, the target transparent conductive film is analyzed with an X-ray diffractometer (XRD apparatus), and a specific diffraction peak indicating a crystal structure is not detected. When this is confirmed, it is determined that the transparent conductive film is amorphous. At this time, if a material having crystallinity is used for the base substrate, the crystal structure of the substrate may be detected. Therefore, an amorphous substrate such as glass is suitable as the base substrate.

  The thickness of the transparent conductive film is not particularly limited, but may be in the range of 10 nm to 200 nm, for example, from the point that low resistivity and high light transmittance in visible light are obtained, and in the range of 10 nm to 100 nm. It is good.

  The oxide material used as the material of the transparent conductive film of the present disclosure is, for example, mixed with indium oxide and an oxide of at least one element selected from the group consisting of boron, magnesium, and aluminum and sintered. Can be obtained.

For example, boron-doped indium oxide will be described as an example of a method for manufacturing the above oxide material.
As an example of a method for producing boron-doped indium oxide as a raw material of the transparent conductive film of the present disclosure, a mixing step of mixing indium oxide and boron oxide to obtain a mixture, and molding the obtained mixture to form a molded body And a sintering step of sintering the obtained molded body to obtain a boron-doped indium oxide oxide sintered body.

  In the mixing step, boron oxide serving as a dopant is mixed with indium oxide serving as a base material. As for the mixing ratio of the boron oxide, it is preferable to weigh and mix, for example, an amount of 0.1 atomic% or more and 20 atomic% or less as boron atomic% with respect to boron-doped indium oxide.

  The indium oxide and boron oxide used in the mixing step are preferably in the form of powder. In addition, these average particle diameters are not specifically limited, What has a well-known average particle diameter should just be used. The mixing method of indium oxide and boron oxide is not particularly limited. Either wet mixing or dry mixing may be used, and a known mixing method may be employed.

<Transparent substrate with transparent conductive film and its manufacturing method>
The transparent substrate with a transparent conductive film of the present disclosure includes the transparent substrate and the transparent conductive film of the present disclosure described above on the transparent substrate. Further, the transparent conductive film may be a transparent conductive film formed in a pattern (hereinafter sometimes referred to as “patterned transparent conductive film”).

Moreover, as an example of the method for producing a transparent substrate with a transparent conductive film of the present disclosure, an oxide material of indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum is provided on the transparent substrate. It has the transparent conductive film formation process which uses as a target and forms the transparent conductive film of this indication mentioned above. When the transparent conductive film is a transparent conductive film formed in a pattern, the transparent conductive film forming step and the pattern forming step of forming a pattern on the transparent conductive film are included.
Hereinafter, a transparent substrate with a transparent conductive film will be described together with a manufacturing method.

First, a transparent substrate is prepared. The transparent substrate is not particularly limited, and examples thereof include a glass substrate and a plastic substrate. For example, specific examples of the glass substrate include quartz glass, soda glass, and borosilicate glass. Examples of the plastic substrate include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); cycloolefin resins such as norbornene; polycarbonate resins; polyimide resins and the like.
In addition to these glass substrates and plastic substrates, sapphire substrates and ceramic substrates can also be mentioned.

  Note that in this specification, the transparent substrate represents a substrate having a visible light transmittance of 10% or more. Visible light represents light in the wavelength region of 380 nm to 780 nm.

  Next, the transparent conductive film of the present disclosure is formed on the transparent substrate. On the transparent substrate, the transparent conductive film of the present disclosure which is the above-described oxide material is formed. The method for forming the transparent conductive film on the transparent substrate is not particularly limited, and may be formed by a known method such as a sputtering method or an ion plating method. Among known methods, the sputtering method is preferable in terms of simple operation.

  Hereinafter, as an example of the method for producing a transparent substrate with a transparent conductive film of the present disclosure, a case where the transparent conductive film is an oxide material of boron-doped indium oxide will be described as an example.

First, a transparent substrate with a cleaned surface is prepared.
Next, an oxide sintered body made of indium oxide containing boron is prepared as a target, and the cleaned transparent substrate and the target of indium oxide containing boron are introduced into the chamber of the sputtering apparatus.
Thereafter, the vacuum is evacuated from the chamber of the sputtering apparatus. When the target degree of vacuum (for example, 10 ⁻⁵ Pa to 10 ⁻³ Pa) is reached, gas is introduced. As the gas to be introduced, a rare gas such as argon is used. Also, oxygen is introduced together with the rare gas. The rare gas (for example, argon) and oxygen introduced into the chamber may be mixed by introducing each gas, or a mixed gas in which a rare gas and oxygen are mixed in advance may be introduced.
For example, when argon (Ar) is introduced as a rare gas and oxygen (O ₂ ) is further introduced to form the transparent conductive film of the present disclosure, the oxygen ratio (volume%) in the chamber is For example, it is desirable that the total amount of argon and oxygen be 0.1 volume% or more and 20 volume% or less.
The ratio of oxygen _{(O 2)} (vol%) is calculated by the following equation.
(Formula) Ratio (volume%) of oxygen (O ₂ ) = {O ₂ / (Ar + O ₂ )} × 100
The proportion of oxygen in the chamber can be adjusted by the flow rate ratio of the oxygen flow rate and the argon flow rate. Moreover, it can also adjust with the density | concentration ratio of oxygen and argon mixed beforehand.

In order to improve film quality and conductivity, hydrogen gas or nitrogen gas may be added together with a mixed gas of argon and oxygen in addition to a mixed gas of argon and oxygen.
When a mixed gas of argon and oxygen (hydrogen gas or nitrogen gas as necessary) is introduced and the pressure in the chamber is stabilized, electric power (for example, 50 W or more and 400 W or less) is applied in order to generate plasma. Pre-sputtering may be performed until the target surface is clean. After pre-sputtering is completed, the shutter is opened and sputtering is started. When the desired film thickness is reached, the shutter is closed and film formation is completed. The temperature at the time of film formation may be room temperature (for example, 25 ° C.), and the substrate may be heated (for example, in a range from room temperature to 300 ° C. or less) as necessary.

  Through the above process, a transparent substrate with a transparent conductive film in which a transparent conductive film of indium oxide containing boron is formed on the transparent substrate is obtained.

The transparent substrate with a transparent conductive film obtained in the above step may be subjected to heat treatment as necessary. When moisture is removed by the heat treatment, the stability as the transparent conductive film tends to increase. In the case of forming a pattern on the transparent conductive film, it is preferable that the pattern is formed in an amorphous state even when heat treatment is performed because a conventional pattern forming method using a weak acid can be easily adopted.
Note that the conditions of the heat treatment when the heat treatment is performed may be performed in accordance with target characteristics (for example, the degree of crystallization). For example, when the transparent conductive film is crystallized, the temperature condition of the heat treatment is preferably high. Moreover, what is necessary is just to perform heat processing using the well-known heat processing furnace in air | atmosphere, for example.

  Next, a transparent substrate with a transparent conductive film having a transparent conductive film formed in a pattern will be described together with its manufacturing method. A transparent substrate with a transparent conductive film having a patterned transparent conductive film can be obtained by, for example, a generally known photolithography process. The photolithography process is a process of applying and drying a photoresist, exposing, developing, etching, and stripping the resist.

  Hereinafter, as an example of the method for producing a transparent substrate with a transparent conductive film of the present disclosure, a case where the transparent conductive film is an oxide material of boron-doped indium oxide will be described as an example.

  Examples of the transparent substrate include the same substrates as those described above. The process up to the transparent conductive film forming process is the same as the process described in the transparent substrate with a transparent conductive film and the manufacturing method thereof.

  The transparent conductive film on the transparent substrate obtained in the process of the method for producing a transparent substrate with a transparent conductive film described above can easily obtain amorphous characteristics. The amorphous transparent conductive film can be easily etched with a weak acid such as a conventional aqueous solution containing oxalic acid.

Hereinafter, a transparent conductive film (patterned transparent conductive film) formed in a pattern by performing pattern processing by etching will be described. Etching is roughly classified into wet etching performed in a solution and dry etching performed by introducing a gas into a vacuum chamber.
Examples of the etching method for forming the patterned transparent conductive film include wet etching and dry etching. Whichever etching method is employed, a pattern can be formed on the transparent conductive film.
Among these, as an etching method, wet etching with a weak acid, which is conventionally used in a manufacturing process of industrial products for large area panel applications, is suitable. When wet etching is applied, the resist may be either a positive resist or a negative resist.
Note that it is preferable to use a weak acid etching solution containing oxalic acid (oxalic acid-based etchant) because damage to the base (eg, a transparent substrate) after the etching is suppressed.

Next, wet etching with a weak acid will be described.
First, a transparent substrate with a transparent conductive film on which a transparent conductive film of indium oxide containing boron formed on a transparent substrate is formed is prepared. Then, a photoresist film is formed on the transparent conductive film by a known coating method such as spin coating or spray coating. The photoresist film coating solution is baked after coating to volatilize the solvent. Thereafter, ultraviolet rays are exposed through a mask in which a predetermined pattern is inverted to expose the resist, and then the pattern is developed with a developer suitable for the resist. Next, after baking in an oven or the like to remove moisture, the substrate is immersed in an etching solution of weak acid containing oxalic acid to dissolve unnecessary portions. Thereafter, the resist is removed with a dedicated resist stripping solution, and unnecessary moisture is blown away, whereby a transparent conductive film formed in a pattern is obtained.

A known coating solution may be used as the coating solution for the photoresist film. Moreover, what is necessary is just to employ | adopt a well-known apparatus and well-known irradiation conditions for the apparatus which exposes an ultraviolet-ray, and the irradiation amount of an ultraviolet-ray.
Further, the shape of the pattern is not particularly limited. What is necessary is just to determine according to target pattern shapes, such as a diamond (rhombus) shape, a triangular shape, and a square shape.

  Through the above-described steps, a transparent substrate with a transparent conductive film is obtained in which a transparent conductive film made of an oxide material made of indium oxide containing boron is formed on a transparent substrate.

  The transparent substrate with a transparent conductive film on which the patterned transparent conductive film obtained in the above step is formed may be subjected to heat treatment as necessary. The heat treatment conditions for the heat treatment may be performed in accordance with target characteristics (for example, the degree of crystallization).

  By such a pattern formation method, it is possible to form a complex two-dimensional pattern on the transparent conductive film. Moreover, since it can etch easily with weak acids, such as aqueous solution containing an oxalic acid, the selection ratio with a structure and a device comprised with materials other than a transparent conductive film can be made high. In particular, application to the manufacture of touch panel sensors is useful.

  Moreover, according to the said process, the transparent conductive film which is excellent in electroconductivity and transparency, for example, the transparency improvement by laminated structure (for example, refer Unexamined-Japanese-Patent No. 2010-086684), and the electrical conductivity improvement by metal fine wire addition (For example, refer to JP-A-2015-005495), a special structure may not be employed, and an additional material may not be used. For this reason, the conventional ITO film forming process can be used as it is, and a high-performance transparent conductive film (or patterned transparent conductive film) can be realized on the substrate simply by replacing the target.

  In the description of the transparent substrate with a transparent conductive film and the manufacturing method thereof, the transparent conductive film has been described using an example of an oxide material made of indium oxide containing boron, but the present invention is not limited thereto. is not. The transparent substrate with a transparent conductive film of the present disclosure is similar to the process described above even when the oxide material is indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum. It is obtained by manufacturing in the process.

<Touch panel>
The touch panel of this indication is provided with the transparent substrate with a transparent conductive film of this indication. The board | substrate with a transparent conductive film of this indication is applicable to the touch sensor of various types of touch panels. For example, examples of the touch panel include a projected capacitive touch panel, a surface capacitive touch panel, and a resistive touch panel.

  An example of a touch panel to which the substrate with a transparent conductive film of the present disclosure is applied will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of a cross-sectional structure of a touch panel using the transparent conductive film of the present disclosure.

The touch panel shown in FIG. 1 has a structure in which a first electrode, a spacer insulating film, a second electrode, and a passivation film (protective film) are stacked in this order on a transparent substrate.
In the touch panel shown in FIG. 1, 100 is a touch panel, 11 is a transparent substrate, 13 is a spacer film, 15 is a passivation film (protective film), 21 is a first electrode, and 23 is a second electrode. In the following description, reference numerals are omitted.
The transparent substrate is for supporting a transparent conductive film, an insulator and the like deposited on the transparent substrate, and the same material as that of the transparent substrate described above is used.
For example, the first electrode may be a Y-direction electrode and the second electrode may be an X-direction electrode. Of course, even if the first electrode is an X-direction electrode and the second electrode is a Y-direction electrode, it functions as a touch panel.
An example of the spacer insulating film is an insulating inorganic transparent material. For example, specific examples include oxides such as SiO ₂ , Al ₂ O ₃ , HfO ₂ , Y ₂ O ₃ , and ZrO ₂ ; nitrides such as Si ₃ N ₄ and AlN; and oxynitrides such as SiON. .
As long as the first electrode and the second electrode can be electrically insulated, the spacer insulating film is not limited to the insulating inorganic transparent material, and may be an insulating organic polymer material. Specific examples include acrylic resins, epoxy resins, silicone resins, and fluorine resins. In addition to these, polyvinyl alcohol, polystyrene, polyimide, polyvinylphenol, polypropylene, polyethylene glycol and the like can be mentioned.
Further, these insulating inorganic transparent materials and insulating organic polymer materials can also be used as a passivation film for isolating the second electrode from the atmosphere.

The touch panel shown in FIG. 1 includes, as an example, a process of providing an insulating spacer on a transparent substrate with a transparent conductive film having a transparent conductive film formed in a pattern shape of the present disclosure, and a second electrode on the spacer. You may have a process and the process of providing a passivation film (protective film) on the 2nd electrode.
Alternatively, the touch panel shown in FIG. 1 includes, as an example, a first step of providing an insulating spacer on a transparent substrate with a transparent conductive film having a transparent conductive film formed in a pattern shape of the present disclosure, and a passivation film ( You may have 2 processes which provide a 2nd electrode on a protective film), and a 3rd process of laminating | stacking a spacer surface and a 2nd electrode surface so that it may oppose.
The insulating spacer is not particularly limited, and may be formed of a material made of an inorganic transparent material or an organic polymer material, for example.

The touch panel to which the substrate with a transparent conductive film of the present disclosure is applied is not limited to the touch panel shown in FIG. 1 described above. The touch panel shown in FIG. 1 is merely an example to which the substrate with a transparent conductive film of the present disclosure is applied, and can be applied to touch panels of various modes.
Further, the size of the touch panel is not particularly limited, and the touch panel can be applied to a known size touch panel.

  Since the transparent conductive film of the present disclosure uses highly stable indium oxide as a base material, it does not contain highly unstable zinc and thus has excellent reliability. In addition, since a dopant material having a band gap higher than that of tin oxide and having a short bond distance to oxygen atoms is added, light transmission with visible light is low and resistivity is low. For this reason, the transparent conductive film of this indication is an oxide material useful in both transparency and electroconductivity.

  Further, since the transparent conductive film of the present disclosure has high light transmittance and low resistivity, a touch panel with high added value that does not impair the visibility of the display panel can be realized. The high light transmittance in visible light can contribute to the reduction of the power consumption of the backlight when used in a display panel, and thus can contribute to the reduction in power consumption and long life of the entire device. For this reason, it is useful not only for a touch panel, but also for application of a liquid crystal display device used for a smart phone, a tablet terminal, an in-car car navigation system, and the like, and an organic electroluminescence display panel.

Furthermore, when used as an anode of an organic EL element or an electrode of a light emitting / receiving element such as an LED or a photodiode, it is superior in efficiency of taking in and taking out light than a conventional transparent electrode material. Therefore, a great effect is brought about in the reduction of power consumption, high efficiency and long life of the element.
Moreover, since it can suppress the light absorption by a transparent electrode part if it uses as an electrode of a solar cell, it can contribute to the improvement of electric power generation efficiency. Therefore, it is also useful for electrodes of various light receiving and emitting elements such as solar cells.
In addition, since the transparent conductive film of the present disclosure has high light transmittance and low resistivity, there is a possibility that it can be applied to information transmission and information exchange using an IC card in a transparent place such as glass. .

Examples will be described below, but the transparent conductive film of the present disclosure is not limited to these examples. In the following description, “part” and “%” are all based on mass unless otherwise specified.
In addition, it is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the idea described in the claims, and the technical scope of the present disclosure is naturally also included. It is understood that it belongs to.

<Example 1>
First, an oxide material of boron-doped indium oxide obtained by mixing 95% by mass of indium oxide (In ₂ O ₃ ) and 5% by mass of boron oxide (B ₂ O ₃ ) was prepared as a target. did.
Next, quartz glass was used as a substrate, and this quartz glass substrate and a prepared boron-doped indium oxide target were placed in a chamber of a sputtering apparatus. Then, 50 W of electric power was applied at room temperature (25 ° C.) in a vacuum atmosphere (5 × 10 ⁻⁴ Pa) of a mixed gas of 95 vol% argon gas and 5 vol% oxygen gas (atmospheric pressure 0.5 Pa), and sputtering was performed. By a method, a transparent conductive film made of an oxide material made of boron-doped indium oxide having a thickness of 50 nm was formed on a quartz glass substrate.

<Examples 2 and 3, Comparative Examples 1 and 2>
As a target, indium oxide (In ₂ O ₃ ) is changed to an oxide material of boron-doped indium oxide obtained by mixing 95% by mass and boron oxide (B ₂ O ₃ ) 5% by mass, Except having changed into the oxide of the element shown in Table 2, it carried out similarly to Example 1, and obtained the board | substrate with a transparent conductive film.

<Evaluation>
(Light transmittance)
The light transmittance in visible light of the substrate with a transparent conductive film obtained in each example was measured. The measuring method is as follows. Measurement was performed at a measurement wavelength of 300 to 800 nm using a spectrophotometer (manufactured by Shimadzu Corporation, UVmini-1240). The measurement results are shown in FIG. The transmittance is the transmittance of the transparent conductive film formed on the quartz glass substrate, and is shown as data including light absorption on the quartz glass substrate. Table 2 shows the results of light transmittance at 550 nm.

(Resistivity)
The substrate with a transparent conductive film obtained in each example was heat-treated (annealed) in an argon gas containing 3% by volume of hydrogen gas at 550 ° C. for 30 minutes. And about the transparent conductive film of the board | substrate with a transparent conductive film before heat processing, and the transparent conductive film after heat processing, a resistivity is measured by a four-point probe method using a resistivity meter (manufactured by NP Corporation, Model sigma-5 +). It was measured. From the obtained resistivity, the resistivity ratio of the resistivity after heat treatment to the resistivity before heat treatment (resistivity after heat treatment / resistivity before heat treatment) was obtained. The results are shown in Table 2. In Table 2, it is expressed as resistance after annealing / resistance before annealing.

<Confirmation of amorphous material>
The substrate with a transparent conductive film obtained in each example was subjected to heat treatment (annealing treatment) in the atmosphere at 250 ° C. for 10 minutes. The transparent conductive film on the substrate with the transparent conductive film subjected to the heat treatment was measured for the transparent conductive film by an X-ray diffraction θ-2θ method using an X-ray diffraction analyzer (RINT2200VK / PC, manufactured by Rigaku Corporation). An X-ray diffraction spectrum in a diffraction angle range of 10 ° to 80 ° was observed to confirm that it was amorphous. The results are shown in FIG.

<Preparation of substrate with patterned transparent conductive film>
From the results shown in FIG. 3, it can be seen that the transparent conductive film of the present disclosure is amorphous. From this, it is considered that the etching suitability with the oxalic acid-based etchant is good.
Therefore, the quartz glass substrate is changed to a silicon substrate, and a boron-doped indium oxide transparent conductive film is formed on the silicon substrate according to the same procedure as in the first embodiment. A substrate was produced. Further, the quartz glass substrate is changed to a silicon substrate, and a silicon-doped indium oxide transparent conductive film is formed on the silicon substrate according to the same procedure as in Comparative Example 1, with the silicon-doped indium oxide transparent conductive film. A substrate was produced. And according to the following operation procedure, the pattern was formed in the transparent conductive film of each board | substrate with a transparent conductive film, and the etching suitability by an oxalic-acid type etchant was confirmed.

  Etching of the transparent conductive film was performed by wet etching using a commercially available general-purpose ITO etchant (manufactured by Kanto Chemical Co., Inc., ITO-07N). A positive photoresist (OFPR-800LB 100 cp, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to a transparent conductive film (thickness: 50 nm) formed on a silicon substrate by a spin coating method at a speed of 3000 rpm for 30 seconds. And applied. Thereafter, baking was performed on a hot plate at 120 ° C. for 5 minutes to evaporate unnecessary solvent. At this time, the film thickness of the photoresist was 3 μm. Next, using a double-sided mask aligner (Union Optics, PEM-800), a portion of the substrate on which the transparent conductive film was formed was masked and exposed for 7 seconds. Subsequently, it was immersed in a developer for positive photoresist (Tokyo Ohka Kogyo Co., Ltd., NMD-3 2.38%) for 3 minutes, and the exposed portion of the photoresist was dissolved to form a photoresist pattern. The substrate after development was washed with pure water and then baked on a hot plate at 110 ° C. for 2 minutes to remove unnecessary moisture. The substrate with the transparent conductive film having the photoresist pattern formed as described above was immersed in the ITO etchant heated to 30 ° C. Thereafter, the photoresist was removed using a resist stripping solution (manufactured by Tokyo Ohka Kogyo Co., Ltd., stripping solution 105), washed with pure water, and then water was blown off with an air blow to obtain a transparent conductive film pattern.

  The cross section of the obtained substrate with a transparent conductive film after pattern formation was measured using a surface level difference meter (Bruker, Dektak-XT). The results are shown in FIG. 4 and FIG. 4 and 5, B-doped indium indicates boron-doped indium oxide, and Si-doped indium indicates silicon-doped indium oxide.

From the results of Examples, it can be seen that the transparent conductive film of the present disclosure has low resistivity and high light transmittance in visible light. In particular, boron-doped indium oxide has a lower light transmittance in the visible light region than conventional silicon-doped indium oxide, but has an excellent resistance ratio and is a well-balanced material.
On the other hand, magnesium-doped indium oxide has a low light transmittance around 400 nm, but shows a light transmittance equivalent to that of boron-doped indium oxide in the region of 550 nm or more. Therefore, magnesium-doped indium oxide is useful for applications that require absorptance of light from the ultraviolet region to the blue region (for example, applications that require a blue light cut). In addition, it can be seen that magnesium-doped indium oxide is useful as an alternative to titanium-doped indium oxide because the resistance ratio is smaller than that of conventional titanium-doped indium oxide.
On the other hand, aluminum-doped indium oxide has better light transmittance in the visible light region than conventional titanium-doped indium oxide. Moreover, the resistance ratio is smaller than that of conventional titanium-doped indium oxide. This indicates that aluminum-doped indium oxide is useful as an alternative to titanium-doped indium oxide.

  In addition, the transparent conductive film of the present disclosure is applicable to a conventional etching process because it has good etching suitability with an oxalic acid-based etchant, similarly to the conventional silicon-doped indium oxide. Therefore, the transparent conductive film of the present disclosure is a useful material that can be easily applied to applications in which a conventional transparent conductive film is applied.

100 touch panel, 11 transparent substrate, 13 spacer film, 15 passivation film (protective film), 21 first electrode, 23 second electrode

Claims (9)

  A transparent conductive film that is an oxide material made of indium oxide containing at least one element selected from the group consisting of boron, magnesium, and aluminum.   2. The transparent conductive film according to claim 1, wherein the content of the element is 0.1 atomic% or more and 25 atomic% or less with respect to the entire oxide material.   The transparent conductive film according to claim 1, wherein the oxide material is amorphous.   The transparent conductive film according to claim 1, wherein the element is boron. A transparent substrate;
On the transparent substrate, the transparent conductive film according to any one of claims 1 to 4,
A transparent substrate with a transparent conductive film.   The transparent substrate with a transparent conductive film according to claim 5, wherein the transparent conductive film is a transparent conductive film formed in a pattern.   The manufacturing method of the transparent substrate with a transparent conductive film which has the transparent conductive film formation process which makes the target the indium oxide containing a boron on a transparent substrate, and forms the transparent conductive film of any one of Claims 1-4.   Furthermore, the manufacturing method of the transparent substrate with a transparent conductive film of Claim 7 which has a pattern formation process which forms a pattern in the said transparent conductive film.   A touch panel provided with the transparent substrate with a transparent conductive film according to claim 5 or 6.