Conductive laminate and method for manufacturing the conductive laminate

Abstract

To provide a conductive laminate capable of achieving both high transmittance and low electric resistance, and various optical devices equipped with the same.SOLUTION: A conductive laminate 1 comprises a transparent substrate 2. On at least one side of the transparent substrate 2, following layers are laminated from the transparent substrate 2 side in this order: a first transparent material layer 3 that does not contain zinc, a metal layer 4 containing silver as a main component, in contact with the first transparent material layer 3, and a second transparent material layer 5 in contact with the metal layer 4. . The thickness of the transparent substrate 2 is 20 μm or more and 200 μm or less; the metal layer 4 has a silver atomic ratio of 90% or more; the second transparent material layer 5 is made of a metal oxide containing zinc; the thickness of the first transparent material layer 3 is 30 nm or more and 80 nm or less; the thickness of the second transparent material layer 5 is greater than 30 nm and 70 nm or less; the first transparent material layer 3 and the second transparent material layer 5 are made from different materials; the thickness of the metal layer 4 is 7 nm or more and less than 15 nm; the transmittance of the entire conductive laminate 1 in the stacking direction is 90% or more; and a surface resistance measured using the surface on which the second transparent material layer 5 is provided is 30 Ω / sq or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present technology relates to a conductive laminate used in, for example, a touch panel, a light control element, an electrophoretic optical element, a light emitting element, and the like. [Background technology]

[0002] Transparent, conductive materials have been used in a variety of optical devices, including touch panels that are stacked on image sensors to detect touched positions by changes in capacitance, light-adjusting devices that use electrochromism to electrically adjust the intensity of external light, light-emitting devices that use electroluminescence, and electrophoretic optical devices that use an electric field to manipulate charged particles dispersed in a liquid.

[0003] The electrodes used in these optical devices are required to be optically transparent, and also to have high electrical conductivity due to operational issues.

[0004] For this reason, transparent materials with low electrical resistance are required. ITO, a composite oxide of indium and tin, is a commonly used material of this type and has already occupied a large position in the market.

[0005] However, ITO has low resistance, and in order to increase its transparency, it is necessary to form the film at high temperatures or to apply heat treatment after film formation, which poses challenges when used on substrates and elements that are sensitive to heat.

[0006] For this reason, efforts are being made to develop materials that can be used without heating, have low resistance, and are highly transparent, and zinc-based oxides such as Zn-O, In-Zn-O (IZO), Al-Zn-O (AZO), and Sn-Zn-O (ZTO) are being considered as alternative materials to ITO.

[0007] Among zinc-based oxides, AZO and ZTO are preferred because they do not contain indium, which is feared to have an adverse effect on the human body.

[0008] On the other hand, plasma televisions and other devices emit electromagnetic waves from their screens due to their construction. Various transparent materials have been developed to absorb these waves, but it was discovered that a laminate consisting of a very thin silver film sandwiched between transparent materials with a high refractive index was extremely effective, and extensive research and development was carried out on this material.

[0009] This laminate is made conductive by silver, and the light interference effect between the high refractive index material and the silver suppresses surface reflection and increases transmittance, achieving high transmittance and low resistance.

[0010] There are also examples where this laminate is applied to the optical devices mentioned above. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 4820738 [Non-patent literature]

[0012] [Non-Patent Document 1] Appl.Phys.A(2014) 116:1287-1291 Summary of the Invention [Problem to be solved by the invention]

[0013] As described above, transparent conductive films that are both transparent and conductive have many potential applications, but even lower resistance and higher transmittance are required to achieve the power savings and high-speed operation of the above-mentioned elements. However, with metal oxides such as ITO, it is necessary to increase the thickness of the film to reduce the resistance, and increasing the thickness of the film reduces the transmittance, making it difficult to obtain sufficient characteristics.

[0014] Furthermore, a laminate with high transmittance and low resistance can be achieved in optical simulations by combining materials and designing the film thickness, and since the silver film absorbs light in the simulations, it is preferable to make the silver thickness thin.

[0015] However, in reality, when the film is formed, the amount of light absorbed does not change even if the thickness of the silver is changed, and light absorption in areas unrelated to thickness is the main factor, which has a significant impact on the overall transmittance.

[0016] Therefore, it has been difficult to obtain a transparent conductive film having a transmittance of more than 90% and a surface resistance of 20 Ω / □ or less.

[0017] Therefore, the present technology has been developed in consideration of such problems, and its purpose is to provide a conductive laminate that can achieve both high transmittance and low electrical resistance, various optical devices equipped with the same, and a method for manufacturing the conductive laminate. [Means for solving the problem]

[0018] As a result of extensive research into solving the above-mentioned problems, the inventors of the present invention discovered that in a conductive laminate in which a first transparent material layer, a metal layer mainly composed of silver, and a second transparent material layer are laminated in this order from the substrate side, when the first transparent material layer is composed of a metal oxide that does not contain zinc and the second transparent material layer is composed of a metal oxide that contains zinc, light absorption of the laminate can be suppressed, and high transmittance and low electrical resistance can be achieved, leading to the completion of the present invention.

[0019] That is, the conductive laminate according to the present technology comprises a transparent substrate, and on at least one surface of the transparent substrate, a first transparent material layer that does not contain zinc, a metal layer that is in contact with the first transparent material layer and has silver as its main component, and a second transparent material layer that is in contact with the metal layer, stacked in this order from the transparent substrate side, wherein the thickness of the transparent substrate is 20 μm or more and 200 μm or less, the metal layer has an atomic ratio of silver of 90% or more, the second transparent material layer is composed of a metal oxide that contains zinc, the thickness of the first transparent material layer is 30 nm or more and 80 nm or less, the thickness of the second transparent material layer is more than 30 nm and 70 nm or less, the first transparent material layer and the second transparent material layer are made of different materials, the thickness of the metal layer is 7 nm or more and less than 15 nm, the transmittance in the stacking direction of the entire conductive laminate is 90% or more, and the surface resistance measured on the surface on which the second transparent material layer is provided is 30 Ω / □ or less.

[0020] In addition, a method for manufacturing a conductive laminate according to the present technology includes a step of stacking, on at least one surface of a transparent substrate, a first transparent material layer that does not contain zinc, a metal layer that is in contact with the first transparent material layer and has silver as its main component, and a second transparent material layer that is in contact with the metal layer, in this order from the transparent substrate side, wherein the thickness of the transparent substrate is 20 μm or more and 200 μm or less, the metal layer has an atomic ratio of silver of 90% or more, the second transparent material layer is composed of a metal oxide that contains zinc, the thickness of the first transparent material layer is 30 nm or more and 80 nm or less, the thickness of the second transparent material layer is more than 30 nm and 70 nm or less, the first transparent material layer and the second transparent material layer are made of different materials, the thickness of the metal layer is 7 nm or more and less than 15 nm, the transmittance in the stacking direction of the entire conductive laminate is 90% or more, and the surface resistance measured on the surface on which the second transparent material layer is provided is 30 Ω / □ or less. [Effects of the Invention]

[0021] According to this technology, a first transparent material that does not contain zinc element is formed on a substrate, followed by the deposition of silver or a silver alloy, and then a second transparent material that contains zinc element is formed, thereby suppressing the generation of a light absorption layer at the interface and providing a conductive laminate with low electrical resistance and high transmittance.

[0022] As a result, according to the present technology, it is possible to provide a conductive laminate having low electrical resistance and high transmittance, which can be applied as an electrode for various optical devices such as high-performance touch panels that are power-saving and have high transmittance, dimming elements, electrophoretic elements, and light-emitting elements. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows the configuration of a conductive laminate to which the technology is applied. [Figure 2] FIG. 2 is a perspective view showing the internal configuration of the thin film forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, a conductive laminate to which the present technology is applied and a method for manufacturing a conductive laminate will be described in detail with reference to the drawings. It should be noted that the present technology is not limited to the following embodiments, and various modifications are possible within the scope of the present technology. Furthermore, the drawings are schematic, and the ratios of the dimensions may differ from the actual dimensions. Specific dimensions should be determined with reference to the following explanation. It should be noted that the drawings also include portions in which the dimensional relationships and ratios differ from one another.

[0025] [Conductive laminate] Figure 1 is a cross-sectional view that schematically shows the configuration of a conductive laminate 1 to which the technology is applied. As shown in Figure 1, the conductive laminate 1 is a conductive laminate 1 that includes a transparent substrate 2, and on at least one surface of the transparent substrate 2, a first transparent material layer 3, a metal layer 4 containing silver as a main component, and a second transparent material layer 5 that are laminated in this order from the transparent substrate 2 side, where the first transparent material layer 3 is made of a metal oxide that does not contain zinc, and the second transparent material layer 5 is made of a metal oxide that contains zinc.

[0026] Sputtering, a vacuum film-forming technique, can be used to form the layers 3 to 5 of the conductive laminate 1. The inventors have investigated the lamination of various transparent materials and silver by sputtering and found that an absorbing layer (hereinafter referred to as a "light absorbing layer") that causes light absorption is formed at the interface between the transparent material and silver. Furthermore, the inventors have found that there are two interfaces between the transparent material and silver: one between the first transparent material layer 3 and the silver that constitutes the metal layer 4, and the other between the silver that constitutes the metal layer 4 and the second transparent material layer 5. A light absorbing layer exists at each interface, and the mechanisms by which each light absorbing layer is formed are different.

[0027] The first light-absorbing layer between the first transparent material layer 3 and the silver constituting the metal layer 4 is formed when the first transparent material layer 3 is deposited on the transparent substrate 2 and then the silver is deposited by sputtering or other methods. Specifically, silver atoms ejected at high speed from the target lose kinetic energy upon reaching the transparent substrate 2 and settle on the surface. If the interaction between the silver and the metal constituting the first transparent material layer 3 is strong, they will alloy with each other on the first transparent material layer 3 side, resulting in the formation of a light-absorbing layer (first light-absorbing layer). Zinc has a wide solid solution range with silver and is an element that interacts strongly with silver, so it easily forms a light-absorbing layer. Generally, a strong interaction can suppress the formation of islands on the silver surface and suppress the absorption by the island-shaped silver, but even when a layer is formed, a certain amount of light-absorbing layer will still be formed.

[0028] Therefore, when a material that has little interaction with silver, such as a metal oxide of Nb, Ti, Zr, Hf, Ta, W, or Mo, is used as the first transparent material that constitutes the first transparent material layer 3, it was found that an extremely thin silver film forms an island structure, resulting in large light absorption, but when silver is layered to a certain thickness or more, it does not form a first light absorption layer formed by an alloy layer with the first transparent material, and only small light absorption occurs due to silver alone. It was also found that the minimum film thickness is 7 nm or more.

[0029] The second light-absorbing layer between the silver constituting the metal layer 4 and the second transparent material layer 5 can be formed when the second transparent material layer 5 is deposited on the metal layer 4 by sputtering or other methods. Specifically, the metal element and oxygen atoms that will form the second transparent material layer 5 reach the surface of the transparent substrate 2, whose surface is covered with silver. However, if the interaction between the silver and the metal element is weak, the second transparent material layer 5 does not spread sufficiently, forming numerous small voids at the interface, where light absorption occurs. On the other hand, if a metal oxide containing zinc is used as the second transparent material, the wettability on the surface of the transparent substrate 2 covered with silver is improved, forming a good interface. Moreover, because the bond between zinc and oxygen is strong, the zinc forms an oxide film before forming an alloy with silver, and therefore no light-absorbing layer (second light-absorbing layer) is formed by an alloy layer.

[0030] Currently, zinc oxide and zinc alloy composite oxide are practical conductive oxides that can be used to form the second transparent material layer 5. Zinc oxide and zinc alloy composite oxide are preferred because they have good contact resistance when substantially transferring charges from the outside to the surface of the conductive laminate 1. It can be said that.

[0031] In this way, a transparent material that does not contain zinc, industrially oxides of Nb, Ti, Zr, Hf, Ta, W, Mo, etc., and composite oxides thereof, is used as the first transparent material that constitutes the first transparent material layer 3, and the first transparent material is deposited on the transparent substrate 2 by sputtering or the like, and then a silver film of 7 nm or more is deposited by sputtering or the like as the metal layer 4, and an oxide containing zinc is deposited by sputtering or the like as the second transparent material that constitutes the second transparent material layer 5, and these are stacked in this order, thereby suppressing light absorption at the interfaces of each layer 3 to 5 and achieving a conductive laminate 1 with high transmittance.

[0032] The first transparent material constituting the first transparent material layer 3 is preferably zinc-free, but a high refractive index material with a refractive index of 1.8 or higher is preferred to suppress surface reflection through optical interference. Examples include oxides of Nb, Ti, Zr, Hf, Ta, W, and Mo, and composite oxides thereof. Furthermore, one or more other elements may be added to these elements in a range not exceeding 50 atomic %.

[0033] The metal layer 4 is a metal layer whose main component is silver, and may contain pure silver or an additive element in a range not exceeding 10 atomic % overall. In other words, in the present technology, "mainly composed of silver" means containing 90 atomic % or more of silver or pure silver. Furthermore, since silver easily forms island-like films with a thickness thinner than 7 nm, a thickness of 7 nm or more is preferable. There is no particular upper limit on the thickness of the silver, but it is preferably less than 15 nm. With a thickness of 15 nm or more, light absorption within the silver layer is greater than absorption at the interface, reducing the effectiveness of the present technology.

[0034] The second transparent material constituting the second transparent material layer 5 preferably contains zinc, but from the viewpoints of optical properties, electrical conductivity, and chemical stability, one or more types of zinc may be added within a range not exceeding 50 atomic %.

[0035] Thus, according to the present technology, a first transparent material not containing zinc is formed on a transparent substrate 2, followed by the formation of a film of silver or a silver alloy, and then a second transparent material containing zinc. This suppresses the formation of a light-absorbing layer at each interface, thereby obtaining a conductive laminate 1 having low electrical resistance and high transmittance. Such a conductive laminate 1 according to the present technology has low electrical resistance and high transmittance. Therefore, according to the present technology, it is possible to provide a power-saving, high-performance optical device using at least one conductive laminate, such as a touch panel, a light control element, an electrophoretic optical element, a light-emitting element, an antenna, etc., using a conductive laminate as at least one pole of an electrode.

[0036] Below, we will explain in detail each layer that constitutes the conductive laminate 1. As described above, the conductive laminate 1 to which the present technology is applied includes a transparent substrate 2, and on at least one surface of the transparent substrate 2, a first transparent material layer 3, a metal layer 4 containing silver as a main component, and a second transparent material layer 5, which are laminated in this order from the transparent substrate 2 side.

[0037] <Transparent substrate> The transparent substrate 2 of the present invention can be made of either a glass substrate or a resin film. When a resin film is used as the transparent substrate 2, it can be manufactured by a roll-to-roll method, thereby improving production efficiency.

[0038] The material for such a resin film is not particularly limited, but examples that can be used include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyaramid, polyimide, polycarbonate, polyethylene, polypropylene, triacetyl cellulose (TAC), polycycloolefin (COC, COP), etc.

[0039] The thickness of the transparent substrate 2 is not particularly limited, but in the case of a resin film, it is preferably 20 μm or more and 200 μm or less, taking into consideration ease of handling during production and thinning of the member.

[0040] In the conductive laminate 1 to which the present technology is applied, the transparent substrate 2 preferably has a light transmittance of 88% or more.

[0041] From the viewpoint of improving the scratch resistance of the transparent substrate 2, a thin film of, for example, an acrylic resin may be formed on both sides of the transparent substrate 2 by, for example, solution coating.

[0042] <First transparent material layer> The first transparent material layer 3 is made of a metal oxide that does not contain zinc, and oxides of substances that have little interaction with silver, such as Nb, Ti, Zr, Hf, Ta, W, and Mo, can be suitably used. These may also be composite oxides containing a single element or multiple elements, and may contain elements other than zinc at a concentration of 50 atomic % or less. The thickness of the first transparent material layer 3 is not particularly limited, and can be set to a film thickness that maximizes transmittance depending on the material composition. The specific thickness of the first transparent material layer 3 can be, for example, in the range of 30 to 80 nm.

[0043] The method for forming the first transparent material layer 3 is not particularly limited, but from the viewpoint of improving production efficiency and achieving a uniform film thickness distribution, it is preferable to use a sputtering method.

[0044] Furthermore, the first transparent material layer 3 may be formed into a plurality of layers from the viewpoint of moisture resistance, etc. In this case, it is preferable that at least the transparent material layer in contact with the metal layer 4 is made of a metal oxide that does not contain zinc, such as an oxide of a substance that has little interaction with silver, such as Nb, Ti, Zr, Hf, Ta, W, or Mo.

[0045] <Metal layer> The metal layer 4 laminated on the first transparent material layer 3 is a metal layer containing silver as its main component. The metal layer 4 may contain an additive element within a range not exceeding 10 atomic % overall. In other words, the metal layer 4 according to the present technology is composed of 90 atomic % or more of silver or pure silver.

[0046] Furthermore, the metal layer 4 preferably has a thickness of 7 nm or more. If the film thickness is thinner than 7 nm, island-like films are easily formed, which may impair light transmittance. There is no particular upper limit on the film thickness, but if the film thickness is 15 nm or more, light absorption within the silver layer may be greater than absorption at the interface, which may reduce the effect of the present invention.

[0047] The method for forming the metal layer 4 is not particularly limited, but it is preferable to use a sputtering method in view of the fact that it is preferable to form the second transparent material layer 5 continuously after forming the metal layer 4, and from the viewpoints of improving production efficiency and achieving a uniform film thickness distribution.

[0048] <Second transparent material layer> The second transparent material layer 5 laminated on the metal layer 4 is made of an oxide containing zinc. From the viewpoints of optical properties, electrical conductivity, and chemical stability, the second transparent material layer 5 may contain one or more elements other than zinc in an amount not exceeding 50 atomic %. The thickness of the second transparent material layer 5 is not particularly limited, and can be set to a thickness that maximizes the transmittance depending on the material composition. The specific thickness of the second transparent material layer 5 can be, for example, in the range of 30 to 70 nm.

[0049] The method for forming the second transparent material layer 5 is not particularly limited, but it is preferable to use a sputtering method in order to form the second transparent material layer 5 continuously after forming the metal layer 4, to improve production efficiency, and to make the film thickness distribution uniform.

[0050] Furthermore, from the viewpoint of scratch resistance, the second transparent material layer 5 may be formed into multiple layers. In this case, at least the transparent material layer in contact with the metal layer 4 is made of an oxide containing zinc, and from the viewpoint of optical properties, electrical conductivity, and chemical stability, one or more elements may be added in a range not exceeding 50 atomic %. Furthermore, it is preferable that the other layers also be made of electrically conductive transparent oxides in order to maintain good electrical conductivity.

[0051] In the conductive laminate 1 shown in FIG. 1, the first transparent material layer 3, the metal layer 4, and the second transparent material layer 5 are laminated on one surface of the transparent substrate 2. However, in the conductive laminate 1 according to the present technology, the first transparent material layer 3, the metal layer 4, and the second transparent material layer 5 may of course be laminated on the other surface of the transparent substrate 2 or on both surfaces of the transparent substrate 2.

[0052] [Manufacturing process of conductive laminate] Such a conductive laminate 1 can be manufactured by stacking a first transparent material layer 3, a metal layer 4 containing silver as its main component, and a second transparent material layer 5 on at least one surface of a transparent substrate 2 in this order from the transparent substrate 2 side.

[0053] The first transparent material layer 3, the metal layer 4, and the second transparent material layer 5 can be formed using, for example, the thin film formation apparatus described in JP 2014-34701 A. Figure 2 is a perspective view showing the internal configuration of the thin film formation apparatus described in JP 2014-34701 A. This thin film formation apparatus forms films by sputtering on a film substrate using a roll-to-roll method, and can accommodate multiple sputtering targets. Moreover, once the rolls are set, it is possible to form films of multiple different materials while maintaining a vacuum atmosphere.

[0054] Furthermore, with this thin film forming apparatus, oxygen gas can be introduced into the plasma in addition to argon gas, which is the sputtering gas, during sputtering, thereby forming an oxide of the target material on the film substrate.

[0055] The configuration of the thin film forming apparatus is described in detail below. This thin film forming apparatus includes a measurement unit that measures the optical characteristics in the width direction of the thin film formed on the substrate film when the substrate film is continuously supplied in the longitudinal direction, a supply unit that has multiple gas nozzles in the width direction of the substrate film and supplies a reactive gas to the vicinity of the target, and a control unit that controls the flow rate of the reactive gas ejected from each gas nozzle based on the optical characteristics in the width direction measured in the measurement unit, thereby enabling the formation of a thin film with a uniform thickness in both the longitudinal and width directions.

[0056] As a specific configuration, it is preferable to include a film formation unit having a supply unit, a sputtering electrode that applies a voltage to the target, and a plasma measurement unit that measures the plasma emission spectrum in the width direction of the substrate film during film formation. This allows the control unit to control the flow rate of the reactive gas ejected from each gas nozzle and the voltage applied to the target based on the optical characteristics in the width direction in the measurement unit and the emission spectrum in the plasma measurement unit, making it possible to form a thin film with a more uniform thickness in the width direction.

[0057] In addition, as a specific configuration, it is preferable to have an unwinding section that unwinds the substrate film in the longitudinal direction, a film-forming unit in which multiple film-forming sections are arranged in the longitudinal direction of the substrate film, and a winding section that winds up the substrate film on which a thin film has been formed in the film-forming unit. This allows a multilayer thin film to be formed from the unwinding to the winding of the substrate film. Furthermore, it is preferable that the measurement section be installed after each film-forming section, but it is also preferable that the measurement section be installed at least after the last film-forming section, i.e., between the film-forming unit and the winding section. This allows the optical properties of both single-layer thin films and multilayer thin films to be measured.

[0058] The thin film forming apparatus shown in FIG. 2 is a device that runs a base film, which is a substrate film, wound around a can roll, and forms a thin film on the surface of the base film by sputtering.

[0059] This thin film forming apparatus supplies a base film 10 (transparent substrate 2) from an unwinding roll 11, which is an unwinding section, and takes up the base film 10 on which a thin film has been formed, by a winding roll 12, which is a winding section. The apparatus also includes a first film forming chamber unit and a second film forming chamber unit, which are film forming units, within a vacuum chamber. The vacuum chamber is connected to a vacuum pump that exhausts air, and can be adjusted to a predetermined vacuum level.

[0060] The first film formation chamber unit and the second film formation chamber unit are equipped with a first can roll 21 and a second can roll 22, respectively, and a plurality of sputtering chambers SP1-10, which are film formation units, are fixed so as to face the outer peripheral surfaces of the can rolls 21 and 22. In each of the sputtering chambers SP1-10, a predetermined target is attached on an electrode, and a supply unit having a plurality of gas nozzles in the width direction of the base film 10 is provided.

[0061] The thin film forming apparatus also includes an optical monitor 31, which is a measuring unit that measures optical properties between the first and second film forming chamber units, i.e., after film formation in sputtering chamber SP5. This allows for control of film formation on intermediate products after the first film forming chamber unit and reduces adjustment time when adjusting for a single layer. The apparatus also includes an optical monitor 32, which is a measuring unit that measures optical properties after the second film forming chamber unit, i.e., after film formation in sputtering chamber SP10. This allows for confirmation of the quality of the film formed on the final product after the second film forming chamber unit.

[0062] As will be described later, the optical monitors 31 and 32 use an optical head capable of scanning in the width direction to measure the optical characteristics in the width direction of the thin film formed on the base film 10. These optical monitors 31 and 32 measure, for example, the peak wavelength of reflectance as an optical characteristic, and convert it into optical thickness to obtain the optical thickness distribution in the width direction.

[0063] The thin film forming apparatus configured as described above can obtain a multilayer thin film by unwinding the base film 10 from the unwinding roll 11, forming a thin film on the base film 10 while the first can roll 21 and the second can roll 22 are being transported, and then winding it up by the winding roll 12. Here, the optical characteristics of the thin film formed on the base film 10 in the width direction are measured by the optical monitors 31 and 32, and the flow rate of the reactive gas from each gas nozzle provided in the width direction is controlled based on the optical characteristics, thereby forming a thin film of uniform thickness in the longitudinal and width directions. [Example]

[0064] The present technology will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0065] Example 1 A first transparent material layer, a metal layer, and a second transparent material layer were sequentially formed on a transparent substrate using the thin film forming apparatus described in JP 2014-34701 A shown in Figure 2. A 50 μm thick COP film was used as the transparent substrate.

[0066] The thin film forming apparatus can simultaneously and sequentially deposit thin films of multiple materials. In this example, targets of niobium oxide, silver, and zinc-tin composite oxide were placed in this order, starting from the side closest to the film unwinding side. Each target was connected to an independent power supply, allowing any desired power to be applied and discharged. Furthermore, each target was housed in an independent container, and the partition separating the targets had only a small gap near the can roll, making it possible to achieve substantially different gas atmospheres.

[0067] The entire vacuum chamber of this thin film deposition device was 1×10 -3 After evacuating the chamber to below 100 Pa, argon gas was introduced into the first cathode section of the vacuum chamber, where the niobium oxide was placed, at a flow rate of 150 sccm, while adjusting the mass flow controller. Electrical power was applied to the niobium oxide target to discharge the material, and a film was formed by sputtering. To suppress light absorption by the niobium oxide due to oxygen deficiency, 6 sccm of oxygen was added to form a transparent oxide layer. The film was run at a speed of 3 m / min. The power was adjusted so that a 46 nm thick niobium oxide film could be formed at a speed of 3 m / min, after measuring the relationship between power and film thickness in advance.

[0068] Niobium oxide was formed in the first cathode, and then a silver thin film was formed in the second cathode. Specifically, argon gas was introduced into the second cathode of the vacuum chamber while adjusting the flow rate to 450 sccm using a mass flow controller, and power was applied to the silver target to discharge and form a film by sputtering. In this example, two adjacent cathodes were used, but this is not necessarily required. Depending on the device configuration, one cathode chamber may not be used, and the entire cathode chamber may serve as a partition. The power was adjusted so that a silver thin film with a thickness of 9 nm could be formed at a running speed of 3 m / min after measuring the relationship between power and film thickness in advance.

[0069] After forming a thin silver film at the second cathode, a zinc-tin composite oxide film was formed at the third cathode. Specifically, argon gas was introduced into the third cathode of the vacuum chamber while adjusting the flow rate to 150 sccm using a mass flow controller. Electrical power was applied to the zinc-tin composite oxide target to discharge and form a film by sputtering. A small amount of oxygen was introduced separately from the argon gas while adjusting the mass flow controller. The amount of oxygen was adjusted to avoid poor conductivity due to oxygen deficiency or excess, resulting in a high-quality transparent conductive oxide. In this example, two adjacent cathodes were used, but this is not necessarily required. Depending on the device configuration, one cathode chamber may not be used, and the entire cathode chamber may serve as a partition. The power was adjusted after measuring the relationship between power and film thickness in advance, so that a zinc-tin composite oxide film with a thickness of 50 nm was formed at a running speed of 3 m / min.

[0070] All film thicknesses were calculated in advance by computer simulation and designed to maximize transmittance.

[0071] After the three layers were formed, the film was continuously wound up. After the film was wound up as shown in Figure 1, air was introduced into the entire device, and the sample was removed and used as a sample.

[0072] <Example 2> A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 49 nm, the thickness of the silver film to 8 nm, and the thickness of the zinc-tin composite oxide film to 52 nm.

[0073] Example 3 A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 52 nm, the thickness of the silver film to 7 nm, and the thickness of the zinc-tin composite oxide film to 53 nm.

[0074] Example 4 A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 43 nm, the thickness of the silver film to 10 nm, and the thickness of the zinc-tin composite oxide film to 49 nm.

[0075] <Example 5> A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 40 nm, the thickness of the silver film to 11 nm, and the thickness of the zinc-tin composite oxide film to 47 nm.

[0076] Example 6 A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 38 nm, the thickness of the silver film to 12 nm, and the thickness of the zinc-tin composite oxide film to 46 nm.

[0077] Example 7 A sample was prepared under the same conditions as in Example 1, except that titanium oxide was used as the first transparent material and the film thickness was adjusted to 39 nm, the silver film thickness to 10 nm, and the zinc-tin composite oxide film thickness to 52 nm.

[0078] Example 8 A sample was prepared under the same conditions as in Example 1, except that zirconium oxide was used as the first transparent material and the film thickness was adjusted to 71 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 42 nm.

[0079] Example 9 A sample was prepared under the same conditions as in Example 1, except that hafnium oxide was used as the first transparent material and the film thickness was adjusted to 62 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 47 nm.

[0080] Example 10 A sample was prepared under the same conditions as in Example 1, except that tantalum pentoxide was used as the first transparent material and the film thickness was adjusted to 58 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 50 nm.

[0081] Example 11 A sample was prepared under the same conditions as in Example 1, except that tungsten oxide was used as the first transparent material and the film thickness was adjusted to 63 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 47 nm. Example 12

[0082] A sample was prepared under the same conditions as in Example 1, except that molybdenum oxide was used as the first transparent material and the film thickness was adjusted to 65 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 48 nm.

[0083] Example 13 A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 51 nm, the thickness of the silver film was adjusted to 7 nm, and zinc oxide was used as the second transparent material to a thickness of 53 nm.

[0084] Example 14 A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 53 nm, the thickness of the silver film was adjusted to 7 nm, and an indium-zinc composite oxide was used as the second transparent material to a thickness of 51 nm.

[0085] Example 15 A sample was prepared under the same conditions as in Example 1, except that the niobium oxide film thickness was adjusted to 47 nm, the silver film thickness was adjusted to 7 nm, and an aluminum-zinc composite oxide was used as the second transparent material to adjust the film thickness to 58 nm.

[0086] <Comparative Example 1> A sample was prepared under the same conditions as in Example 1, except that zinc oxide was used as the first transparent material and the film thickness was adjusted to 64 nm, the silver film thickness to 7 nm, and the zinc-tin composite oxide film thickness to 46 nm.

[0087] <Comparative Example 2> A sample was prepared under the same conditions as in Example 1, except that the first transparent material was made of zinc-tin composite oxide with a film thickness of 77 nm, the silver film thickness was 7 nm, and the second transparent material was made of niobium oxide with a film thickness of 35 nm.

[0088] <Comparative Example 3> A sample was prepared under the same conditions as in Example 1, except that the thickness of the niobium oxide film was adjusted to 55 nm, the thickness of the silver film to 6 nm, and the thickness of the zinc-tin composite oxide film to 54 nm.

[0089] <Comparative Example 4> A sample was prepared under the same conditions as in Example 1, except that the niobium oxide film thickness was adjusted to 55 nm, the silver film thickness was adjusted to 7 nm, and niobium oxide was used as the second transparent material to a film thickness of 42 nm.

[0090] <Comparative Example 5> A sample was prepared under the same conditions as in Example 1, except that zinc oxide was used as the first transparent material with a film thickness of 64 nm, the silver film thickness was 7 nm, and zinc oxide was used as the second transparent material with a film thickness of 46 nm.

[0091] <Comparative Example 6> A sample was prepared under the same conditions as in Example 1, except that zinc oxide was used as the first transparent material with a film thickness of 66 nm, silver with a film thickness of 7 nm, and indium-zinc composite oxide was used as the second transparent material with a film thickness of 44 nm.

[0092] <Comparative Example 7> A sample was prepared under the same conditions as in Example 1, except that zinc oxide was used as the first transparent material with a film thickness of 58 nm, silver with a film thickness of 7 nm, and aluminum-zinc composite oxide was used as the second transparent material with a film thickness of 51 nm.

[0093] <Comparative Example 8> A sample was prepared under the same conditions as in Example 1, except that zinc oxide was used as the first transparent material, with a film thickness of 74 nm, silver with a film thickness of 8 nm, and titanium oxide was used as the second transparent material, with a film thickness of 31 nm.

[0094] [Evaluation results] Each sample was cut to a desired size and then measured and evaluated. Surface resistance was measured using Loresta GP (registered trademark) (manufactured by Dia Instruments Co., Ltd.) in accordance with JIS K-7194.

[0095] The total light transmittance was measured in accordance with JIS K-7105 using NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0096] The light absorption was measured using a spectrometer, U-4100 (manufactured by Hitachi High-Technologies Corporation), to measure the transmittance and reflectance at an incident angle of 5°, and the amount shown in the following formula (1) for each value at a wavelength of 550 nm was defined as the light absorption amount. Light absorption (%) = 100 (%) - (transmittance (%) + reflectance (%)) (1)

[0097] In other words, light that is neither reflected nor transmitted is assumed to be converted into heat (absorbed) within the thin film and substrate. In reality, the effective transmittance and reflectance may decrease due to scattering, etc., and the apparent light absorption may appear to increase, but since the substrate used in this invention has extremely low absorption and a smooth surface, the light absorption calculated by the above formula (1) can be considered to be almost entirely due to absorption by the laminated film.

[0098] In the present invention, it is preferable that the surface resistance is as low as possible and the total light transmittance is as high as possible. In commonly used ITO (indium tin oxide) films, the total light transmittance is often 88% at a surface resistance of 100 Ω / □, although this varies depending on the ITO film thickness. Therefore, in order to demonstrate the superiority of the present invention, it is preferable that the resistance is 20 Ω / □ or less and the total light transmittance is 90% or more.

[0099] [Table 1]

[0100] <Examples 1 to 6> As is clear from Table 1, the surface resistance is maintained at 30 Ω / □ or less and the total light transmittance is maintained at 90% or more. Furthermore, although light absorption increases slightly as the silver film thickness increases, this does not have a significant effect on the total light transmittance, and this is due to the suppression of the causes of light absorption identified in the present invention.

[0101] <Examples 7 to 12> The characteristics when the first transparent material layer was changed are shown in comparison with Examples 1 to 6. As is clear from Table 1, the aforementioned surface resistance of 30 Ω / □ or less and total light transmittance of 90% or more are maintained. In other words, it can be seen that the effects shown by the present invention are not limited to when the first transparent material layer is made of niobium oxide, and similar effects can be obtained when a zinc-free metal oxide, specifically titanium oxide, zirconium oxide, hafnium oxide, tantalum pentoxide, tungsten oxide, molybdenum oxide, etc., is used.

[0102] <Examples 13 to 15> In the present invention, in Examples 1 to 12, a tin composite oxide, which exhibits a relatively low resistance as a single layer film, was used as the second transparent material layer, but the present invention is not limited to this. Examples 13 to 15 show the characteristics when the second transparent material layer was changed, compared to Examples 1 to 6. As is clear from Table 1, Examples 13 to 15 also maintain the aforementioned characteristics of a surface resistance of 30 Ω / □ or less and a total light transmittance of 90% or more. In other words, it can be seen that the effects shown in the present invention are not limited to when the second transparent material layer is a zinc-tin composite oxide, and similar effects are exhibited as long as the second transparent material layer is a transparent conductor containing zinc.

[0103] <Comparative Example 1> In Comparative Example 1, zinc oxide was used for the first transparent material layer. As shown in Table 1, the sample according to Comparative Example 1 had a significantly lower total light transmittance than Example 3, which had the same silver film thickness, and also had increased light absorption, indicating that using zinc oxide for the first transparent material layer increases absorption.

[0104] <Comparative Example 2> In Comparative Example 2, a zinc-tin composite oxide was used for the first transparent material layer and niobium oxide for the second transparent material layer, which is the opposite of the structures shown in Examples 1 to 6. As shown in Table 1, the sample of Comparative Example 2 had a lower total light transmittance and an increased light absorption compared to Example 3, which had the same silver film thickness. This suggests that the absorption at the interface between the first transparent material layer and the metal layer (silver) and the interface between the metal layer (silver) and the second transparent material layer occurs via different mechanisms.

[0105] <Comparative Example 3> In Comparative Example 3, the structure was the same as in Examples 1 to 6, but the film thickness of the metal layer (silver) was set to 6 nm. As shown in Table 1, when the film thickness of the metal layer (silver) of the sample according to Comparative Example 3 was reduced, the effect of the present invention could no longer be obtained, the continuity of the thin silver film could not be maintained, and an island-like structure was formed in the film, resulting in a rapid increase in surface resistance and a significant increase in the amount of light absorption.

[0106] <Comparative Example 4> In Comparative Example 4, both the first and second transparent materials were niobium oxide. As shown in Table 1, the sample in Comparative Example 4 had a lower total light transmittance than Example 3, which had the same silver film thickness, indicating that light absorption can be suppressed by using a material containing zinc as the second transparent material. Furthermore, niobium oxide also had low conductivity, resulting in an increase in surface resistance.

[0107] <Comparative Examples 5 to 8> Zinc oxide was used for the first transparent material layer in Comparative Examples 5 to 8. As shown in Table 1, in the samples according to Comparative Examples 5 to 8, even when a material other than zinc-tin composite oxide was used for the second transparent material layer, the total light transmittance did not improve and remained low, indicating that when the first transparent material is an oxide containing zinc, a highly transmittant film cannot be obtained even if any material is used for the second transparent material.

[0108] As explained above, the effects of the present invention were demonstrated from the results of the Examples and Comparative Examples. However, the present invention is not limited to the above-described examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical idea described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0109] 1 conductive laminate, 2 transparent substrate, 3 first transparent material layer, 4 metal layer, 5 second transparent material layer, 10 base film, 11 unwinding roll, 12 winding roll, 21 first can roll, 22 second can roll, 31 optical monitor, 32 optical monitor, SP sputtering chamber

Claims

1. A conductive laminate comprising a transparent substrate, a first transparent material layer made of a metal oxide not containing zinc on at least one surface of the transparent substrate, a metal layer contacting the first transparent material layer and containing silver as a main component, and a second transparent material layer contacting the metal layer, laminated in this order from the transparent substrate side, The thickness of the transparent substrate is 20 μm or more and 200 μm or less, The metal layer has an atomic ratio of silver of 90% or more, the first transparent material layer is made of a metal oxide that has a weaker property than zinc of forming a light absorbing layer at the interface with the metal layer when alloyed with silver, the second transparent material layer is made of a metal oxide containing zinc, the thickness of the first transparent material layer is 30 nm or more and 80 nm or less; the thickness of the second transparent material layer is greater than 30 nm and less than 70 nm; the first transparent material layer and the second transparent material layer are made of different materials; The thickness of the metal layer is 7 nm or more and less than 15 nm, the total light transmittance of the entire conductive laminate in the stacking direction is 90% or more, The surface resistance measured on the surface on which the second transparent material layer is provided is 30 Ω / □ or less. Conductive laminate.

2. The conductive laminate according to claim 1 , wherein the first transparent material layer has a refractive index of 1.8 or more.

3. The method includes a step of laminating, on at least one surface of a transparent substrate, a first transparent material layer made of a metal oxide not containing zinc, a metal layer contacting the first transparent material layer and containing silver as a main component, and a second transparent material layer contacting the metal layer in this order from the transparent substrate side; The thickness of the transparent substrate is 20 μm or more and 200 μm or less, The metal layer has an atomic ratio of silver of 90% or more, the first transparent material layer is made of a metal oxide that has a weaker property than zinc of forming a light absorbing layer at the interface with the metal layer when alloyed with silver, the second transparent material layer is made of a metal oxide containing zinc, the thickness of the first transparent material layer is 30 nm or more and 80 nm or less; the thickness of the second transparent material layer is greater than 30 nm and less than 70 nm; the first transparent material layer and the second transparent material layer are made of different materials; The thickness of the metal layer is 7 nm or more and less than 15 nm, the total light transmittance in the stacking direction of the entire conductive laminate is 90% or more; The surface resistance measured on the surface on which the second transparent material layer is provided is 30 Ω / □ or less. A method for manufacturing a conductive laminate.

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