JP7654592B2 - Transparent Conductive Film - Google Patents

Description

The present invention relates to a transparent conductive film.

Conventionally, a transparent conductive film is known that has a transparent substrate film and a transparent conductive layer (light-transmitting conductive layer) in that order in the thickness direction. The light-transmitting conductive layer is used as a conductive film for patterning transparent electrodes in various devices such as liquid crystal displays, touch panels, and optical sensors. The light-transmitting conductive layer is formed, for example, by forming a film of a conductive oxide on the substrate film by a sputtering method. In the sputtering method, an inert gas such as argon is conventionally used as a sputtering gas for colliding with a target (a film-forming material supply material) and ejecting atoms from the target surface. Technology relating to such transparent conductive films is described, for example, in Patent Document 1 below.

JP 2017-71850 A

The light-transmitting conductive layer of the transparent conductive film is patterned by etching the light-transmitting conductive layer through a specified etching mask. However, the transparent conductive film of Patent Document 1 has a drawback in that the etching rate of the light-transmitting conductive layer is slow in the etching process. A slow etching rate of the light-transmitting conductive layer in the transparent conductive film is undesirable from the viewpoint of the efficiency of the device manufacturing process in which the transparent conductive film is used.

The present invention provides a transparent conductive film suitable for achieving a high etching rate in a light-transmitting conductive layer.

The present invention [1] includes a transparent conductive film comprising a transparent substrate and a light-transmitting conductive layer in this order in the thickness direction, the light-transmitting conductive layer containing krypton and having a resistivity of less than 2.8×10 ⁻⁴ Ω·cm, the light-transmitting conductive layer having a hole mobility μ (cm ² /V·s) and a carrier density n×10 ¹⁹ (cm ⁻³ ), and the ratio of n to μ is 4 or more.

The present invention [2] includes the transparent conductive film described in [1] above, in which the light-transmitting conductive layer contains an indium-containing conductive oxide.

The present invention [3] includes the transparent conductive film according to the above [1] or [2], wherein the Hall mobility is from 5 cm ² /V·s to 40 cm ² /V·s.

The present invention [4] includes the transparent conductive film according to any one of the above [1] to [3], wherein the carrier density is 100×10 ¹⁹ cm ⁻³ or more and 170×10 ¹⁹ cm ⁻³ or less.

The present invention [5] includes the transparent conductive film according to any one of [1] to [4] above, in which the light-transmitting conductive layer is patterned.

The present invention [6] includes the transparent conductive film according to any one of the above [1] to [5], wherein the light-transmitting conductive layer has a specific resistance of less than 2.2×10 ⁻⁴ Ω·cm.

In the transparent conductive film of the present invention, the light-transmitting conductive layer contains krypton and has a resistivity of less than 2.8×10 ⁻⁴ Ω·cm. In addition, in the hole mobility μ (cm ² /V·s) and carrier density n×10 ¹⁹ (cm ⁻³ ) of the light-transmitting conductive layer, the ratio of n to μ is 4 or more. Therefore, the transparent conductive film of the present invention is suitable for achieving a high etching rate in the light-transmitting conductive layer.

1 is a schematic cross-sectional view of one embodiment of a transparent conductive film of the present invention. FIG. 2 shows a method for producing the transparent conductive film shown in FIG. 1. FIG. 2A shows a process for preparing a resin film, FIG. 2B shows a process for forming a functional layer on the resin film, FIG. 2C shows a process for forming a light-transmitting conductive layer on the functional layer, and FIG. 2D shows a process for crystallizing the light-transmitting conductive layer. This shows a case where the light-transmitting conductive layer in the transparent conductive film shown in FIG. 1 is patterned. 1 is a graph showing the relationship between the amount of oxygen introduced when forming a light-transmitting conductive layer by a sputtering method and the resistivity of the formed light-transmitting conductive layer.

Figure 1 is a schematic cross-sectional view of a transparent conductive film X, which is one embodiment of the transparent conductive film of the present invention. The transparent conductive film X includes a transparent substrate 10 and a light-transmitting conductive layer 20, in this order, toward one side in the thickness direction D. The transparent conductive film X has a shape that spreads in a direction (plane direction) perpendicular to the thickness direction D. The transparent conductive film X is an element that is included in touch sensor devices, light control elements, photoelectric conversion elements, heat ray control members, antenna members, electromagnetic wave shielding members, lighting devices, image display devices, and the like.

In this embodiment, the transparent substrate 10 includes a resin film 11 and a functional layer 12, in this order, toward one side of the thickness direction D. The transparent substrate 10 has a shape that extends in a direction (plane direction) perpendicular to the thickness direction D.

The resin film 11 is a flexible, transparent resin film. Examples of the material of the resin film 11 include polyester resin, polyolefin resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resin include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of the acrylic resin include polymethacrylate. Examples of the acrylic resin include polymethacrylate. As the material of the resin film 11, for example, from the viewpoint of transparency and strength, polyolefin resin is preferably used, and more preferably COP is used.

The surface of the resin film 11 facing the functional layer 12 may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

The thickness of the resin film 11 is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 30 μm or more. The thickness of the resin film 11 is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 75 μm or less. These configurations regarding the thickness of the resin film 11 are suitable for ensuring the handleability of the transparent conductive film X.

The total light transmittance (JIS K 7375-2008) of the resin film 11 is preferably 60% or more, more preferably 80% or more, and even more preferably 85% or more. Such a configuration is suitable for ensuring the transparency required of the transparent conductive film X when the transparent conductive film X is provided in a touch sensor device, a light control element, a photoelectric conversion element, a heat ray control member, an antenna member, an electromagnetic wave shielding member, a lighting device, an image display device, and the like. The total light transmittance of the resin film 11 is, for example, 100% or less.

In this embodiment, the functional layer 12 is located on one surface of the resin film 11 in the thickness direction D. In this embodiment, the functional layer 12 is a hard coat layer that prevents scratches from forming on the exposed surface (top surface in FIG. 1) of the light-transmitting conductive layer 20.

The hard coat layer is a cured product of a curable resin composition. Examples of the resin contained in the curable resin composition include polyester resin, acrylic resin, urethane resin, amide resin, silicone resin, epoxy resin, and melamine resin. Examples of the curable resin composition include an ultraviolet-curable resin composition and a heat-curable resin composition. From the viewpoint of being useful for improving the production efficiency of the transparent conductive film X because it can be cured without high-temperature heating, an ultraviolet-curable resin composition is preferably used as the curable resin composition. Specific examples of the ultraviolet-curable resin composition include the composition for forming a hard coat layer described in JP 2016-179686 A.

The surface of the functional layer 12 facing the light-transmitting conductive layer 20 may be subjected to a surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

The thickness of the functional layer 12 as a hard coat layer is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. Such a configuration is suitable for achieving sufficient abrasion resistance in the light-transmitting conductive layer 20. From the viewpoint of ensuring the transparency of the functional layer 12, the thickness of the functional layer 12 as a hard coat layer is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less.

The thickness of the transparent substrate 10 is preferably 1 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 30 μm or more. The thickness of the transparent substrate 10 is preferably 310 μm or less, more preferably 210 μm or less, even more preferably 110 μm or less, and particularly preferably 80 μm or less. These configurations regarding the thickness of the transparent substrate 10 are suitable for ensuring the handleability of the transparent conductive film X.

The total light transmittance (JIS K 7375-2008) of the transparent substrate 10 is preferably 60% or more, more preferably 80% or more, and even more preferably 85% or more. Such a configuration is suitable for ensuring the transparency required of the transparent conductive film X when the transparent conductive film X is provided in a touch sensor device, a light control element, a photoelectric conversion element, a heat ray control member, an antenna member, an electromagnetic wave shielding member, a lighting device, an image display device, and the like. The total light transmittance of the transparent substrate 10 is, for example, 100% or less.

In this embodiment, the light-transmitting conductive layer 20 is located on one surface of the transparent substrate 10 in the thickness direction D. The light-transmitting conductive layer 20 is a crystalline film that is both light-transmitting and conductive.

The light-transmitting conductive layer 20 is a layer formed from a light-transmitting conductive material. The light-transmitting conductive material contains, for example, a conductive oxide as a main component.

Examples of the conductive oxide include metal oxides containing at least one metal or semimetal selected from the group consisting of In, Sn, Zn, Ga, Sb, Ti, Si, Zr, Mg, Al, Au, Ag, Cu, Pd, and W. Specifically, examples of the conductive oxide include indium-containing conductive oxides and antimony-containing conductive oxides. Examples of the indium-containing conductive oxide include indium tin composite oxide (ITO), indium zinc composite oxide (IZO), indium gallium composite oxide (IGO), and indium gallium zinc composite oxide (IGZO). Examples of the antimony-containing conductive oxide include antimony tin composite oxide (ATO). From the viewpoint of achieving high transparency and good conductivity, the conductive oxide is preferably an indium-containing conductive oxide, and more preferably ITO. This ITO may contain a metal or semimetal other than In and Sn in an amount less than the respective contents of In and Sn.

When ITO is used as the conductive oxide, the ratio of the content of tin oxide to the total content of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ) in the light-transmitting conductive layer 20 (tin oxide content ratio) is preferably 1 mass% or more, more preferably 3 mass% or more, even more preferably 5 mass% or more, and particularly preferably 7 mass% or more. Such a configuration is suitable for ensuring the durability of the light-transmitting conductive layer 20. In addition, from the viewpoint of obtaining a light-transmitting conductive layer 20 that is easily crystallized by heating, the tin oxide content ratio is preferably 15 mass% or less, more preferably 13 mass% or less, and even more preferably 12 mass% or less. The above content ratio of tin oxide is obtained from the XPS spectrum measured by X-ray photoelectron spectroscopy for the measurement object.

The tin oxide content in the light-transmitting conductive layer 20 may be non-uniform in the thickness direction D. For example, the light-transmitting conductive layer 20 may include a first layer having a relatively high tin oxide content and a second layer having a relatively low tin oxide content, in this order from the transparent substrate 10 side. The tin oxide content in the first layer is preferably 5% by mass or more, more preferably 8% by mass or more. The tin oxide content in the first layer is preferably 15% by mass or less, more preferably 13% by mass or less. The tin oxide content in the second layer is preferably 0.5% by mass or more, more preferably 2% by mass or more. The tin oxide content in the second layer is preferably 8% by mass or less, more preferably 5% by mass or less. The ratio of the thickness of the first layer to the thickness of the light-transmitting conductive layer 20 is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. Furthermore, the ratio of the thickness of the second layer to the thickness of the light-transmitting conductive layer 20 is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less.

The light-transmitting conductive layer 20 contains krypton (Kr) as rare gas atoms. In this embodiment, the rare gas atoms in the light-transmitting conductive layer 20 are derived from rare gas atoms used as a sputtering gas in the sputtering method described below. In this embodiment, the light-transmitting conductive layer 20 is a film formed by the sputtering method (sputtered film).

The configuration in which the light-transmitting conductive layer 20 contains Kr is suitable for achieving low resistance in the light-transmitting conductive layer 20. This configuration is also suitable for achieving a high etching rate when the light-transmitting conductive layer 20 is etched, for example, for patterning. The presence or absence of Kr in the light-transmitting conductive layer 20 is identified, for example, by X-ray fluorescence analysis, which will be described later in the examples.

The content of Kr in the light-transmitting conductive layer 20 is, for example, 0.5 atomic % or less, preferably 0.3 atomic % or less, and more preferably 0.2 atomic % or less, throughout the entire area in the thickness direction D. This configuration is suitable for achieving good crystal growth and forming large crystal grains when the amorphous light-transmitting conductive layer (light-transmitting conductive layer 20' described below) is crystallized by heating to form the light-transmitting conductive layer 20 during the manufacturing process of the transparent conductive film X, and is therefore suitable for obtaining a light-transmitting conductive layer 20 with low resistance (the larger the crystal grains in the light-transmitting conductive layer 20, the lower the resistance of the light-transmitting conductive layer 20). In addition, the content of Kr in the light-transmitting conductive layer 20 is, for example, 0.0001 atomic % or more throughout the entire area in the thickness direction D.

The Kr content in the light-transmitting conductive layer 20 may be non-uniform in the thickness direction D. For example, in the thickness direction D, the Kr content may gradually increase or decrease as it moves away from the transparent substrate 10. Alternatively, in the thickness direction D, a partial region in which the Kr content gradually increases as it moves away from the transparent substrate 10 may be located on the transparent substrate 10 side, and a partial region in which the Kr content gradually decreases as it moves away from the transparent substrate 10 may be located on the opposite side to the transparent substrate 10. Alternatively, in the thickness direction D, a partial region in which the Kr content gradually decreases as it moves away from the transparent substrate 10 may be located on the transparent substrate 10 side, and a partial region in which the Kr content gradually increases as it moves away from the transparent substrate 10 may be located on the opposite side to the transparent substrate 10.

It is preferable that the light-transmitting conductive layer 20 contains only Kr as a rare gas atom. Such a configuration is preferable from the viewpoint of realizing low resistance in the light-transmitting conductive layer 20. In addition, this configuration is preferable from the viewpoint of realizing a high etching rate when the light-transmitting conductive layer 20 is etched, for example, for patterning.

When the light-transmitting conductive layer 20 contains rare gas atoms other than Kr, examples of the rare gas atoms other than Kr include argon (Ar) and xenon (Xe). From the viewpoint of reducing the manufacturing cost of the transparent conductive film X, the light-transmitting conductive layer 20 preferably does not contain Xe.

The content of rare gas atoms (including Kr) in the light-transmitting conductive layer 20 is, for example, 0.5 atomic % or less, preferably 0.3 atomic % or less, and more preferably 0.2 atomic % or less, throughout the entire region in the thickness direction D. This configuration is suitable for achieving good crystal growth and forming large crystal grains when the amorphous light-transmitting conductive layer is crystallized by heating to form the light-transmitting conductive layer 20 during the manufacturing process of the transparent conductive film X, and is therefore suitable for obtaining a light-transmitting conductive layer 20 with low resistance. In addition, the content of rare gas atoms in the light-transmitting conductive layer 20 is, for example, 0.0001 atomic % or more throughout the entire region in the thickness direction D.

The thickness of the light-transmitting conductive layer 20 is, for example, 10 nm or more, preferably 25 nm or more, more preferably 30 nm or more, even more preferably 35 nm or more, and particularly preferably 40 nm or more. Such a configuration is suitable for reducing the resistance of the light-transmitting conductive layer 20. The thickness of the light-transmitting conductive layer 20 is, for example, 1000 nm or less, preferably less than 300 nm, more preferably 250 nm or less, even more preferably 200 nm or less, even more preferably 160 nm or less, particularly preferably less than 150 nm, and most preferably 148 nm or less. Such a configuration is suitable for reducing the compressive residual stress of the light-transmitting conductive layer 20 and suppressing warping of the transparent conductive film X.

The total light transmittance (JIS K 7375-2008) of the light-transmitting conductive layer 20 is preferably 60% or more, more preferably 80% or more, and even more preferably 85% or more. Such a configuration is suitable for ensuring transparency in the light-transmitting conductive layer 20. In addition, the total light transmittance of the light-transmitting conductive layer 20 is, for example, 100% or less.

The surface resistance of the light-transmitting conductive layer 20 is, for example, 200 Ω/□ or less, preferably 70 Ω/□ or less, more preferably 55 Ω/□ or less, even more preferably 50 Ω/□ or less, and particularly preferably 45 Ω/□ or less. The surface resistance of the light-transmitting conductive layer 20 is, for example, 1 Ω/□ or more. These configurations regarding the surface resistance are suitable for ensuring the low resistance required of the light-transmitting conductive layer 20 when the transparent conductive film X is provided in a touch sensor device, a light control element, a photoelectric conversion element, a heat ray control member, an antenna member, an electromagnetic wave shielding member, a lighting device, and an image display device. The surface resistance can be measured by a four-terminal method in accordance with JIS K7194.

The resistivity of the light-transmitting conductive layer 20 is less than 2.8×10 ⁻⁴ Ω·cm, preferably 2.2×10 ⁻⁴ Ω·cm or less, more preferably 2×10 ⁻⁴ Ω·cm or less, even more preferably 1.8×10 ⁻⁴ Ω·cm or less, and particularly preferably 1.7×10 ⁻⁴ Ω·cm or less. The resistivity of the light-transmitting conductive layer 20 is, for example, 0.1×10 ⁻⁴ Ω·cm or more. These configurations regarding the resistivity are suitable for ensuring the low resistivity required of the light-transmitting conductive layer 20 when the transparent conductive film X is provided in a touch sensor device, a light control element, a photoelectric conversion element, a heat ray control member, an antenna member, an electromagnetic wave shielding member, a lighting device, an image display device, and the like. The resistivity is calculated by multiplying the surface resistance by the thickness.

The hole mobility in the light-transmitting conductive layer 20 is preferably 5 cm ² /V·s or more, more preferably 10 cm ² /V·s or more, and even more preferably 20 cm ² /V·s or more. The hole mobility in the light-transmitting conductive layer 20 is preferably 40 cm ² /V·s or less, more preferably 35 cm ² /V·s or less, and even more preferably 30 cm ² /V·s or less. The hole mobility can be adjusted, for example, by adjusting the Kr content in the light-transmitting conductive layer 20 and adjusting various conditions when sputtering the amorphous light-transmitting conductive layer (light-transmitting conductive layer 20' described below) that is converted into the light-transmitting conductive layer 20 by heating. Examples of the conditions include the temperature of the base (transparent substrate 10 in this embodiment) on which the amorphous light-transmitting conductive layer is formed, and the sputtering output of the substrate side (transparent substrate 10 in this embodiment). The hole mobility can also be adjusted by adjusting the surface properties, such as the surface shape of the base on which the amorphous light-transmitting conductive layer is formed (in this embodiment, the surface properties of the functional layer 12).

The carrier density in the light-transmitting conductive layer 20 is preferably 100×10 ¹⁹ cm ⁻³ or more, more preferably 120×10 ¹⁹ cm ⁻³ or more. The carrier density in the light-transmitting conductive layer 20 is preferably 170×10 ¹⁹ cm ⁻³ or less, more preferably 150×10 ¹⁹ cm ⁻³ or less. The carrier density can be adjusted, for example, by adjusting the Kr content in the light-transmitting conductive layer 20 and adjusting various conditions when sputtering the amorphous light-transmitting conductive layer (light-transmitting conductive layer 20′ described below) that is converted into the light-transmitting conductive layer 20 by heating. Such conditions include, for example, the temperature of the base (transparent substrate 10 in this embodiment) on which the amorphous light-transmitting conductive layer is formed, and the amount of oxygen introduced into the film formation chamber. The carrier density can also be adjusted by adjusting the surface properties of the base on which the amorphous light-transmitting conductive layer is formed (in this embodiment, the surface properties of the functional layer 12).

When the hole mobility of the light-transmitting conductive layer 20 is μ (cm ² /V·s) and the carrier density of the light-transmitting conductive layer 20 is n×10 ¹⁹ cm ^-3 , the ratio of n to μ (n/μ) is 4 or more, preferably 4.2 or more, more preferably 4.4 or more, even more preferably 5 or more, and particularly preferably 6 or more. Such a configuration is suitable for achieving a high etching rate in the light-transmitting conductive layer 20. From the viewpoint of achieving both a high etching rate and low resistance in the light-transmitting conductive layer 20, the ratio of n to μ is, for example, 20 or less, preferably 10 or less, and more preferably less than 6.2.

Whether the light-transmitting conductive layer is crystalline can be determined, for example, as follows. First, the light-transmitting conductive layer (light-transmitting conductive layer 20 on transparent substrate 10 in transparent conductive film X) is immersed in hydrochloric acid with a concentration of 5% by mass at 20°C for 15 minutes. Next, the light-transmitting conductive layer is washed with water and then dried. Next, the resistance between a pair of terminals separated by a distance of 15 mm (terminal-to-terminal resistance) is measured on the exposed plane of the light-transmitting conductive layer (the surface of light-transmitting conductive layer 20 opposite transparent substrate 10 in transparent conductive film X). In this measurement, if the terminal-to-terminal resistance is 10 kΩ or less, the light-transmitting conductive layer is crystalline.

The transparent conductive film X is manufactured, for example, as follows.

First, prepare a resin film 11 as shown in FIG. 2A.

Next, as shown in FIG. 2B, a functional layer 12 is formed on one surface of the resin film 11 in the thickness direction D. By forming the functional layer 12 on the resin film 11, the transparent substrate 10 is produced.

The functional layer 12 described above as a hard coat layer can be formed by applying a curable resin composition onto the resin film 11 to form a coating film, and then curing the coating film. When the curable resin composition contains an ultraviolet-curable resin, the coating film is cured by ultraviolet irradiation. When the curable resin composition contains a thermosetting resin, the coating film is cured by heating.

The exposed surface of the functional layer 12 formed on the resin film 11 is subjected to a surface modification treatment as necessary. When plasma treatment is used as the surface modification treatment, argon gas, for example, is used as the inert gas. The discharge power in the plasma treatment is, for example, 100 W or more, and, for example, 500 W or less.

Next, as shown in FIG. 2C, an amorphous light-transmitting conductive layer 20' is formed on the transparent substrate 10 (film formation process). Specifically, a material is deposited on the functional layer 12 of the transparent substrate 10 by a sputtering method to form the amorphous light-transmitting conductive layer 20'. The light-transmitting conductive layer 20' is an amorphous film that has both light transparency and conductivity (the light-transmitting conductive layer 20' is converted into a crystalline light-transmitting conductive layer 20 by heating in the crystallization process described below).

In the sputtering method, it is preferable to use a sputtering deposition apparatus capable of performing a film formation process by a roll-to-roll method. When using a sputtering deposition apparatus of the roll-to-roll method in the manufacture of the transparent conductive film X, a material is deposited on the long transparent substrate 10 while the transparent substrate 10 is running from a pay-out roll to a take-up roll provided in the apparatus, to form the light-transmitting conductive layer 20'. In addition, in the sputtering method, a sputtering deposition apparatus having one deposition chamber may be used, or a sputtering deposition apparatus having multiple deposition chambers arranged in order along the running path of the transparent substrate 10 may be used (when forming the light-transmitting conductive layer 20' including the above-mentioned first layer and second layer, a sputtering deposition apparatus having two or more deposition chambers is used).

Specifically, in the sputtering method, a sputtering gas (inert gas) is introduced into the deposition chamber under vacuum conditions, while a negative voltage is applied to a target placed on a cathode in the deposition chamber. This generates a glow discharge to ionize the gas atoms, and the gas ions collide with the target surface at high speed, ejecting the target material from the target surface, and the ejected target material is deposited on the functional layer 12 in the transparent substrate 10.

As the material of the target placed on the cathode in the film formation chamber, the conductive oxide described above for the light-transmitting conductive layer 20 is used, preferably an indium-containing conductive oxide is used, and more preferably ITO is used. When ITO is used, the ratio of the tin oxide content to the total content of tin oxide and indium oxide in the ITO is preferably 1 mass% or more, more preferably 3 mass% or more, even more preferably 5 mass% or more, particularly preferably 7 mass% or more, and is preferably 15 mass% or less, more preferably 13 mass% or less, and even more preferably 12 mass% or less.

The sputtering method is preferably a reactive sputtering method. In the reactive sputtering method, a reactive gas is introduced into the deposition chamber in addition to the sputtering gas.

When forming a light-transmitting conductive layer 20' containing Kr throughout the entire thickness direction D, the gas introduced into the deposition chamber contains Kr as a sputtering gas and oxygen as a reactive gas. The sputtering gas may contain an inert gas other than Kr. Examples of inert gases other than Kr include rare gas atoms other than Kr. Examples of rare gas atoms include Ar and Xe. When the sputtering gas contains an inert gas other than Kr, the content is preferably 5 vol.% or less, more preferably 3 vol.% or less.

In the reactive sputtering method, the ratio of the amount of oxygen introduced to the total amount of sputtering gas and oxygen introduced into the deposition chamber is, for example, 0.1 flow rate% or more, and, for example, 5 flow rate% or less.

The air pressure in the deposition chamber during deposition by sputtering (sputter deposition) is, for example, 0.02 Pa or more and, for example, 1 Pa or less.

The temperature of the transparent substrate 10 during sputtering deposition is, for example, 100°C or less, preferably 50°C or less, more preferably 30°C or less, and is, for example, -20°C or more, preferably -10°C or more, more preferably -7°C or more.

Examples of power sources for applying voltage to the target include DC power sources, AC power sources, MF power sources, and RF power sources. A DC power source and an RF power source may be used in combination as the power source. The discharge voltage during sputtering deposition is, for example, 200 V or more, and, for example, 400 V or less.

In this manufacturing method, next, as shown in FIG. 2D, the light-transmitting conductive layer 20 is converted from amorphous to crystalline (crystallized) by heating (crystallization step). Examples of heating means include an infrared heater and an oven. From the viewpoint of ensuring a high crystallization rate, the heating temperature is, for example, 100° C. or higher, and preferably 120° C. or higher. From the viewpoint of suppressing the influence of heating on the transparent substrate 10, the heating temperature is, for example, 200° C. or lower, preferably 180° C. or lower, more preferably 170° C. or lower, and even more preferably 165° C. or lower. The heating time is, for example, 6 hours or less, preferably 200 minutes or less, more preferably 150 minutes or less, and even more preferably 90 minutes or less, and for example, 1 minute or more, preferably 5 minutes or more.

In this manner, transparent conductive film X is produced.

The light-transmitting conductive layer 20 in the transparent conductive film X may be patterned as shown in FIG. 3. The light-transmitting conductive layer 20 can be patterned by etching the light-transmitting conductive layer 20 through a specific etching mask. The patterning of the light-transmitting conductive layer 20 may be performed before or after the crystallization process described above. The patterned light-transmitting conductive layer 20 functions, for example, as a wiring pattern.

As described above, in the transparent conductive film X, the light-transmitting conductive layer 20 on the transparent substrate 10 contains krypton and has a resistivity of less than 2.8×10 ⁻⁴ Ω·cm. In addition, when the hole mobility of the light-transmitting conductive layer is μ (cm ² /V·s) and the carrier density is n×10 ¹⁹ (cm ⁻³ ), the ratio of n to μ (n/μ) is 4 or more, preferably 4.2 or more, more preferably 4.4 or more, even more preferably 5 or more, and particularly preferably 6 or more.

This configuration of the transparent conductive film X is suitable for achieving a high etching rate in the light-transmitting conductive layer 20. More specifically, this is as shown in the examples and comparative examples below.

In the transparent conductive film X, the functional layer 12 may be an adhesion improving layer for realizing high adhesion of the light-transmitting conductive layer 20 to the transparent substrate 10. The configuration in which the functional layer 12 is an adhesion improving layer is suitable for ensuring adhesion between the transparent substrate 10 and the light-transmitting conductive layer 20.

The functional layer 12 may be an index-matching layer for adjusting the reflectance of the surface (one side in the thickness direction D) of the transparent substrate 10. The configuration in which the functional layer 12 is an index-matching layer is suitable for making the pattern shape of the light-transmitting conductive layer 20 on the transparent substrate 10 less visible when the light-transmitting conductive layer 20 on the transparent substrate 10 is patterned.

The functional layer 12 may be a peelable functional layer that allows the light-transmitting conductive layer 20 to be practically peeled off from the transparent substrate 10. The configuration in which the functional layer 12 is a peelable functional layer is suitable for peeling the light-transmitting conductive layer 20 off from the transparent substrate 10 and transferring the light-transmitting conductive layer 20 to another member.

The functional layer 12 may be a composite layer in which multiple layers are connected in the thickness direction D. The composite layer preferably includes two or more layers selected from the group consisting of a hard coat layer, an adhesion improving layer, a refractive index adjustment layer, and a release functional layer. Such a configuration is suitable for the functional layer 12 to exhibit the above-mentioned functions of each selected layer in a composite manner. In a preferred embodiment, the functional layer 12 includes an adhesion improving layer, a hard coat layer, and a refractive index adjustment layer on the resin film 11, in this order toward one side of the thickness direction D. In another preferred embodiment, the functional layer 12 includes a release functional layer, a hard coat layer, and a refractive index adjustment layer on the resin film 11, in this order toward one side of the thickness direction D.

The transparent conductive film X is attached to an article and, if necessary, patterned before use. The transparent conductive film X is attached to the article, for example, via an adhesive functional layer.

Examples of the article include elements, members, and devices. That is, examples of the article with a transparent conductive film include an element with a transparent conductive film, a member with a transparent conductive film, and a device with a transparent conductive film.

The elements include, for example, dimming elements and photoelectric conversion elements. The dimming elements include, for example, current-driven dimming elements and electric field-driven dimming elements. The current-driven dimming elements include, for example, electrochromic (EC) dimming elements. The electric field-driven dimming elements include, for example, PDLC (polymer dispersed liquid crystal) dimming elements, PNLC (polymer network liquid crystal) dimming elements, and SPD (suspended particle device) dimming elements. The photoelectric conversion elements include, for example, solar cells. The solar cells include, for example, organic thin-film solar cells and dye-sensitized solar cells. The members include, for example, electromagnetic wave shielding members, heat ray control members, heater members, and antenna members. The devices include, for example, touch sensor devices, lighting devices, and image display devices.

An article with a transparent conductive film is suitable for achieving a high etching rate in the light-transmitting conductive layer 20 of the transparent conductive film X that it comprises, and is therefore suitable for achieving high manufacturing efficiency.

The above-mentioned adhesion functional layer includes, for example, an adhesive layer and a bonding layer. The material of the adhesion functional layer is not particularly limited as long as it has transparency and exhibits adhesion function. The adhesion functional layer is preferably formed from a resin. Examples of the resin include acrylic resin, silicone resin, polyester resin, polyurethane resin, polyamide resin, polyvinyl ether resin, vinyl acetate/vinyl chloride copolymer, modified polyolefin resin, epoxy resin, fluororesin, natural rubber, and synthetic rubber. The resin is preferably an acrylic resin because it exhibits adhesive properties such as cohesiveness, adhesion, and moderate wettability, has excellent transparency, and has excellent weather resistance and heat resistance.

The adhesion functional layer (resin forming the adhesion functional layer) may contain a corrosion inhibitor to inhibit corrosion of the light-transmitting conductive layer 20. The adhesion functional layer (resin forming the adhesion functional layer) may contain a migration inhibitor (e.g., a material disclosed in JP-A-2015-022397) to inhibit migration of the light-transmitting conductive layer 20. The adhesion functional layer (resin forming the adhesion functional layer) may also contain an ultraviolet absorbing agent to inhibit deterioration during outdoor use of the article. Examples of ultraviolet absorbing agents include benzophenone compounds, benzotriazole compounds, salicylic acid compounds, oxalic acid anilide compounds, cyanoacrylate compounds, and triazine compounds.

In addition, when the transparent substrate 10 of the transparent conductive film X is fixed to an article via the adhesive functional layer, the light-transmitting conductive layer 20 (including the light-transmitting conductive layer 20 after patterning) is exposed in the transparent conductive film X. In such a case, a cover layer may be disposed on the exposed surface of the light-transmitting conductive layer 20. The cover layer is a layer that covers the light-transmitting conductive layer 20, and can improve the reliability of the light-transmitting conductive layer 20 and suppress the deterioration of the function of the light-transmitting conductive layer 20 due to damage. Such a cover layer is preferably formed from a dielectric material, and more preferably from a composite material of a resin and an inorganic material. Examples of the resin include the resins described above with respect to the adhesive functional layer. Examples of the inorganic material include inorganic oxides and fluorides. Examples of the inorganic oxide include silicon oxide, titanium oxide, niobium oxide, aluminum oxide, zirconium dioxide, and calcium oxide. Examples of the fluoride include magnesium fluoride. The cover layer (a mixture of resin and inorganic material) may also contain the above-mentioned corrosion inhibitors, migration inhibitors, and UV absorbers.

The present invention will be specifically described below with reference to examples. The present invention is not limited to the examples. In addition, the specific numerical values of the compounding amounts (contents), physical property values, parameters, etc. described below can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than") of the corresponding compounding amounts (contents), physical property values, parameters, etc. described in the above-mentioned "Form for carrying out the invention."

Example 1
A UV-curable resin composition containing an acrylic resin was applied to one side of a long cycloolefin polymer (COP) film (trade name "ZEONOR", thickness 40 μm, manufactured by ZEON Co., Ltd.) as a transparent resin film to form a coating film. Next, the coating film was cured by UV irradiation to form a hard coat layer (thickness 1 μm). Next, a UV-curable resin composition for forming a refractive index adjustment layer (composite resin composition containing zirconia particles) was applied to the hard coat layer to form a coating film. Next, the coating film was cured by UV irradiation to form a refractive index adjustment layer (thickness 90 nm, refractive index 1.62) on the hard coat layer. In this way, a transparent substrate having a resin film, a hard coat layer, and a refractive index adjustment layer in this order was produced.

Next, a 66 nm-thick amorphous light-transmitting conductive layer was formed on the hard coat layer of the transparent substrate by reactive sputtering (film formation process). In the reactive sputtering method, a sputtering film formation device (DC magnetron sputtering device) capable of performing a film formation process by a roll-to-roll method was used. The sputtering film formation conditions in this example are as follows.

As the target, a sintered body of indium oxide and tin oxide (tin oxide concentration was 10% by mass) was used. As a power source for applying a voltage to the target, a DC power source was used. The horizontal magnetic field strength above the target was 90 mT. The film formation temperature (temperature of the transparent substrate on which the light-transmitting conductive layer is laminated) was 20° C. In addition, the film formation chamber was evacuated until the ultimate vacuum in the film formation chamber of the device reached 0.8×10 ⁻⁴ Pa, and then Kr as a sputtering gas and oxygen as a reactive gas were introduced into the film formation chamber, and the pressure in the film formation chamber was set to 0.2 Pa. The ratio of the amount of oxygen introduced to the total amount of Kr and oxygen introduced into the film formation chamber was about 2 flow %, and the amount of oxygen introduced was adjusted so that the resistivity of the film formed was 6.9×10 ⁻⁴ Ω·cm within the region R of the resistivity-oxygen introduction amount curve as shown in FIG. 4. The resistivity-oxygen introduction amount curve shown in FIG. 4 can be prepared by investigating in advance the dependency of the resistivity of the light-transmitting conductive layer on the amount of oxygen introduced when the light-transmitting conductive layer is formed by a reactive sputtering method under the same conditions as described above except for the amount of oxygen introduced.

Next, the light-transmitting conductive layer on the transparent substrate was crystallized by heating in a hot air oven (crystallization process). In this process, the heating temperature was 130°C and the heating time was 1.5 hours.

In this manner, the transparent conductive film of Example 1 was produced. The light-transmitting conductive layer (thickness 66 nm, crystalline) of the transparent conductive film of Example 1 consists of a single Kr-containing ITO layer.

[Examples 2 and 3 and Comparative Example 1]
The transparent conductive films of Examples 2 and 3 and Comparative Example 1 were each produced in the same manner as the transparent conductive film of Example 1, except for the following.

In the film formation process, the thickness of the light-transmitting conductive layer formed was changed from 66 nm to 56 nm (Example 2), 41 nm (Example 3), or 43 nm (Comparative Example 1), and the amount of oxygen introduced was adjusted so that the resistivity of the film formed was changed from 6.9× ¹⁰⁻⁴ Ω·cm to 7.4× ¹⁰⁻⁴ Ω·cm (Example 2), 7.2× ¹⁰⁻⁴ Ω·cm (Example 3), or 7.5× ¹⁰⁻⁴ Ω·cm (Comparative Example 1).

The light-transmitting conductive layer (crystalline) of each transparent conductive film in Examples 2 and 3 and Comparative Example 1 consists of a single Kr-containing ITO layer.

Comparative Example 2
A transparent conductive film of Comparative Example 2 was produced in the same manner as the transparent conductive film of Example 1, except for the following.

In the film formation process, Ar was used as the sputtering gas instead of Kr, the film formation pressure was changed to 0.4 Pa instead of 0.2 Pa, and the amount of oxygen introduced was adjusted so that the resistivity of the formed film was 7.0×10 ⁻⁴ Ω·cm instead of 6.5×10 ⁻⁴ Ω·cm.

The light-transmitting conductive layer (thickness 70 nm, crystalline) of the transparent conductive film of Comparative Example 2 consists of a single Ar-containing ITO layer.

Comparative Example 3
A transparent conductive film of Comparative Example 3 was produced in the same manner as the transparent conductive film of Example 1, except for the following.

In the film formation process, a first sputtering deposition was carried out in sequence to form a first layer (thickness 26 nm) on the transparent substrate, and a second sputtering deposition was carried out in sequence to form a second layer (thickness 4 nm) on the first layer.

The conditions for the first sputtering film formation in this comparative example are as follows. A sintered body of indium oxide and tin oxide (tin oxide concentration: 10% by mass) was used as the target. A DC power supply was used as the power supply for applying a voltage to the target. The horizontal magnetic field strength above the target was 90 mT. The film formation temperature was 20° C. In addition, the first film formation chamber of the apparatus was evacuated until the ultimate vacuum in the first film formation chamber reached 0.8×10 ⁻⁴ Pa, and then Ar as a sputtering gas and oxygen as a reactive gas were introduced into the first film formation chamber, and the pressure in the film formation chamber was set to 0.4 Pa. The amount of oxygen introduced into the film formation chamber was adjusted so that the resistivity of the film formed was 6.2×10 ⁻⁴ Ω·cm.

The conditions for the second sputtering deposition in this comparative example are as follows. A sintered body of indium oxide and tin oxide (tin oxide concentration: 3 mass %) was used as the target. The second deposition chamber included in the apparatus was evacuated until the ultimate vacuum in the second deposition chamber reached 0.8×10 ⁻⁴ Pa, after which Ar as a sputtering gas and oxygen as a reactive gas were introduced into the second deposition chamber, and the pressure in the deposition chamber was set to 0.2 Pa. In this comparative example, the other conditions for the second sputtering deposition were the same as those for the first sputtering deposition.

The light-transmitting conductive layer (thickness 30 nm, crystalline) of the transparent conductive film of Comparative Example 3 has, in order from the transparent substrate side, a first layer (thickness 26 nm) made of an Ar-containing ITO layer and a second layer (thickness 4 nm) made of an Ar-containing ITO layer.

Comparative Example 4
A transparent conductive film of Comparative Example 4 was produced in the same manner as the transparent conductive film of Example 1, except for the following.

In the film formation process, Ar was used as the sputtering gas instead of Kr, the amount of oxygen introduced was adjusted so that the resistivity of the formed film was 3.1× ¹⁰⁻⁴ Ω·cm instead of 6.5× ¹⁰⁻⁴ Ω·cm, and the thickness of the formed light-transmitting conductive layer was 83 nm instead of 66 nm.

The light-transmitting conductive layer (thickness 83 nm, crystalline) of the transparent conductive film of Comparative Example 4 consists of a single Ar-containing ITO layer.

<Thickness of Light-Transmitting Conductive Layer>
The thickness of the light-transmitting conductive layer in each of the transparent conductive films in Examples 1 to 3 and Comparative Examples 1 to 4 was measured by FE-TEM observation. Specifically, first, a cross-sectional observation sample of each of the light-transmitting conductive layers in Examples 1 to 3 and Comparative Examples 1 to 4 was prepared by FIB microsampling. In the FIB microsampling method, an FIB device (trade name "FB2200", manufactured by Hitachi) was used, and the acceleration voltage was set to 10 kV. Next, the thickness of the light-transmitting conductive layer in the cross-sectional observation sample was measured by FE-TEM observation. In the FE-TEM observation, an FE-TEM device (trade name "JEM-2800", manufactured by JEOL) was used, and the acceleration voltage was set to 200 kV.

The thickness of the first layer of the light-transmitting conductive layer in Comparative Example 3 was measured by FE-TEM observation of a cross-sectional observation sample prepared from the intermediate product before the second layer was formed on the first layer. The thickness of the second layer of the light-transmitting conductive layer in Comparative Example 3 was determined by subtracting the thickness of the first layer from the total thickness of the light-transmitting conductive layer in Comparative Example 3.

<Resistivity>
The resistivity of the light-transmitting conductive layer was examined for each of the transparent conductive films of Examples 1 to 3 and Comparative Examples 1 to 4. Specifically, the surface resistance of the light-transmitting conductive layer was measured by a four-terminal method in accordance with JIS K 7194 (1994), and then the resistivity (Ω cm) was calculated by multiplying the surface resistance value by the thickness of the light-transmitting conductive layer. The results are shown in Table 1.

Hall mobility and carrier density
The Hall mobility and carrier density of the light-transmitting conductive layer were measured for each of the transparent conductive films of Examples 1 to 3 and Comparative Examples 1 to 4. A Hall effect measurement system (product name "HL5500PC", manufactured by Bio-Rad) was used for this measurement. The Hall mobility μ (cm ² /V·s) and carrier density n×10 ¹⁹ (cm ⁻³ ) values obtained by this measurement are shown in Table 1. Table 1 also shows the ratio of n to μ (n/μ).

Etching Speed
The etching rate of the light-transmitting conductive layer was examined for each of the transparent conductive films of Examples 1 to 3 and Comparative Examples 1 to 4. Specifically, for the transparent conductive films, one cycle was repeated in which the following first step, second step, and third step were carried out in this order (one cycle was repeated until etching was determined to be complete in the third step based on the criteria described below).

In the first step, the transparent conductive film was immersed in hydrochloric acid with a concentration of 7% by mass. The immersion temperature was 35°C. The immersion time was 15 seconds. In the second step, the transparent conductive film was washed with water and then dried. In the third step, the resistance between a pair of terminals separated by a distance of 15 mm (terminal resistance) was measured on the exposed surface of the light-transmitting conductive layer of the transparent conductive film using a surface resistance measuring tester. If the measured terminal resistance exceeded 50 kΩ or was not measurable, it was determined that etching was completed in the first step of the cycle to which the third step belonged. The etching rate (seconds/nm) was calculated by dividing the cumulative immersion time (etching time) of multiple first steps in multiple cycles by the thickness of the light-transmitting conductive layer. The values are shown in Table 1.

<Confirmation of Kr atoms in the light-transmitting conductive layer>
It was confirmed that each of the light-transmitting conductive layers in Examples 1 to 3 and Comparative Example 1 contained Kr atoms as follows. First, using a scanning X-ray fluorescence analyzer (trade name "ZSX Primus IV", manufactured by Rigaku Corporation), X-ray fluorescence analysis was repeated five times under the following measurement conditions, and the average value of each scanning angle was calculated to create an X-ray spectrum. It was confirmed that the light-transmitting conductive layer contained Kr atoms by confirming that a peak appeared near a scanning angle of 28.2° in the created X-ray spectrum.

<Measurement conditions>
Spectrum: Kr-KA
Measurement diameter: 30 mm
Atmosphere: Vacuum Target: Rh
Tube voltage: 50 kV
Tube current: 60mA
Primary filter: Ni40
Scanning angle (deg): 27.0 to 29.5
Step (deg): 0.020
Speed (deg/min): 0.75
Attenuator: 1/1
Slit: S2
Spectroscopic crystal: LiF (200)
Detector: SC
PHA:100-300

[evaluation]
In each of the transparent conductive films of Examples 1 to 3, the light-transmitting conductive layer contains Kr, and the above-mentioned value of n/μ in the light-transmitting conductive layer is equal to or greater than 4. In each of the transparent conductive films of Examples 1 to 3, a higher etching rate is realized in the light-transmitting conductive layer than in the transparent conductive film of Comparative Example 1 (wherein the value of n/μ is less than 4) and the transparent conductive films of Comparative Examples 2 to 4 (wherein the light-transmitting conductive layer does not contain Kr).

In addition, the transparent conductive films of Examples 1 to 3 (in which the light-transmitting conductive layer contains Kr) have a lower resistivity of the light-transmitting conductive layer than the transparent conductive films of Comparative Examples 2 to 4 (in which the light-transmitting conductive layer does not contain Kr). The transparent conductive films of Examples 2 and 3 (in which the light-transmitting conductive layer contains Kr and the value of n/μ is 4 or more) have a particularly low resistivity of the light-transmitting conductive layer, which is lower than the transparent conductive film of Comparative Example 1 (in which the light-transmitting conductive layer contains Kr but the value of n/μ is less than 4).

The transparent conductive film of the present invention can be used as a conductive film supply material for patterning transparent electrodes in various devices such as liquid crystal displays, touch panels, and optical sensors.

X: transparent conductive film D: thickness direction 10: transparent substrate 11: resin film 12: functional layer 20: light-transmitting conductive layer

Claims (5)

A transparent substrate and a light-transmitting conductive layer are provided in this order in a thickness direction,
the light-transmitting conductive layer is a crystalline film and contains krypton ;
a transparent conductive film, wherein the light-transmitting conductive layer has a hole mobility μ (cm ² /V·s) and a carrier density n×10 ¹⁹ (cm ⁻³ ), and the ratio of n to μ is 4.4 or more and 20 or less . The transparent conductive film according to claim 1, wherein the light-transmitting conductive layer contains an indium-containing conductive oxide. 3. The transparent conductive film according to claim 1, wherein the Hall mobility is from 5 cm ² /V·s to 40 cm ² /V·s. 4. The transparent conductive film according to claim 1, wherein the carrier density is 100×10 ¹⁹ cm ⁻³ or more and 170×10 ¹⁹ cm ⁻³ or less. The transparent conductive film according to claim 1 , wherein the light-transmitting conductive layer is patterned.

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