JP6511876B2 - Laminated transparent conductive film - Google Patents

Description

  The present invention relates to a laminated transparent conductive film.

  The transparent conductive film is used as a display such as a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescence panel (organic EL, inorganic EL) or a transparent electrode of a solar cell etc. It is also used as an infrared protection film.

As a material of the transparent conductive film, ITO obtained by adding tin (Sn) to indium oxide (In ₂ O ₃ ), GZO obtained by adding gallium (Ga) to zinc oxide (ZnO), and tin oxide added with antimony (Sb) (SnO ₂ ) and the like are known, and in particular, ITO is widely used.

  BACKGROUND In recent years, terminals provided with touch panels, such as smartphones and tablet terminals, are rapidly spreading. In these, a touch sensor is provided on a liquid crystal panel, and a cover glass is provided on the outermost surface. The touch sensor unit has a structure in which one or two sheets of ITO film deposited by sputtering on one side or both sides of a glass or film substrate are bonded.

  With the increase in size of touch panels and the increase in accuracy of touch sensor functions, transparent conductive films having high transmittance and low resistance are desired. In particular, focusing on the ease of human light perception that varies depending on the wavelength of light, a transparent conductive film having a high transmittance at the wavelength of 555 nm of light is required. Furthermore, weight reduction of a transparent conductive film is calculated | required. In order to reduce the resistance of the ITO film, it is necessary to increase the thickness of the ITO film or to crystallize the ITO film by thermal annealing. However, as the ITO film becomes thicker, the transmittance decreases. In addition, when glass is replaced with a resin film substrate for weight reduction, it is difficult to perform thermal annealing at high temperature. Therefore, in the ITO film | membrane provided on the resin film base material, it was in a difficult condition to perform resistance reduction, maintaining a high transmittance | permeability.

Several laminated type transparent conductive films configured by a laminated structure of a metal oxide layer and a metal layer have been proposed. Patent Document 1 proposes a structure in which a silver thin film is sandwiched by a mixed oxide film containing indium oxide, and after forming a film on a glass substrate, high transmittance is achieved by annealing at a high temperature of 220 ° C. for 1 hour. Get a rate and low resistance. However, when using a resin film as a base material, it is difficult to perform annealing at a high temperature.
Patent Document 2 proposes a structure in which an ITO film and a silver thin film are laminated by sputtering on a polyethylene terephthalate (PET) film, then a SiOx film is provided by spin coating, and finally an ITO film is provided by sputtering. . In this structure, not only productivity is remarkably deteriorated because the manufacturing method repeatedly uses the sputtering method and the spin coating method, but a high transmittance of 80% or more at a wavelength of 555 nm of light is not obtained.
Patent Document 3 proposes a structure in which an ITO film and a silver film are alternately laminated a plurality of times alternately on a polyethylene terephthalate film as a transparent substrate, and then a metal thin film such as titanium or zirconium is provided on the outermost surface. Although this structure improves the corrosion resistance, only 60% of the transmittance is obtained.

Unexamined-Japanese-Patent No. 9-176837 JP 2000-351170 A JP 2000-202941 A

  An object of the present invention is to provide a lightweight laminated transparent conductive film having both high transmittance and low surface resistance.

The above object of the present invention is achieved by the following constitution.
That is, the present invention comprises a first metal oxide layer, a metal layer, and a second metal oxide layer in this order on a transparent resin substrate, and the first metal oxide layer and the metal layer And an Si interface layer on at least one of the metal layer and the second metal oxide layer, wherein the metal layer is a silver-based silver having a thickness of 6 nm to 12 nm. It is an alloy, and the film thickness of said Si interface layer is 0.5 nm or more and 1.5 nm or less, It is a lamination | stacking transparent conductive film characterized by the above-mentioned.
Such a laminated transparent conductive film can be a laminated transparent conductive film having high transmittance and low surface resistance. With such a laminated transparent conductive film, the touch panel can be made larger and the touch sensor can be made more accurate. More specifically, it can be set as the lamination type transparent conductive film from which the transmittance | permeability of 85% or more in wavelength 555 nm of light, and the surface resistance value of 50 ohms / square or less are obtained.

  ADVANTAGE OF THE INVENTION By this invention, provision of the lightweight laminated type transparent conductive film which made the high transmittance | permeability and the low surface resistance value compatible is attained.

It is a schematic cross section which shows one structural example of embodiment of the laminated transparent conductive film of this invention. It is a schematic cross section which shows the other structural example of embodiment of the laminated type transparent conductive film of this invention. It is a schematic cross section which shows the further another structural example of embodiment of the laminated type transparent conductive film of this invention.

Hereinafter, embodiments of the present invention will be specifically described.
As a configuration example of the laminated transparent conductive film according to the embodiment of the present invention, as shown in FIG. 1, a first metal oxide layer 14, a metal layer 16, a Si interface layer 20, and a second metal layer 16 are formed on a transparent resin substrate 12. The first metal oxide layer 14, the Si interface layer 20, the metal layer 16, and the second metal oxide layer 18 are formed on the transparent resin substrate 12 as shown in FIG. 2. The first metal oxide layer 14, the Si interface layer 20, the metal layer 16, the Si interface layer 20, and the second metal oxide layer 18 are formed on the transparent resin substrate 12 as shown in FIG. What was laminated | stacked sequentially is mentioned.

  The transparent resin substrate 12 may use a resin film, and for example, a resin film such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC) or the like is preferable. In addition, a hard coat layer may be provided on one side or both sides of these resin films. The thickness of the transparent resin substrate 12 is, for example, 10 to 200 μm.

A first metal oxide layer 14 is provided on the transparent resin substrate 12. The first metal oxide layer 14 is provided for adjusting the optical properties and protecting the metal layer 16, and Ti, Zr, Hf, Ta, Si, Al, Mg, Y, Ce, Zn, In, Cr, Nb A composite containing an oxide of at least one metal selected from Sn, Ga, Sb, etc. is used. The composite is preferably composed of a material based on ZnO, In ₂ O ₃ or SnO ₂ . Here, the main component means that the molar ratio in the whole is 50% or more. This makes it easy to maintain the conductivity of the laminated transparent conductive film.

The film thickness of the first metal oxide layer 14 is preferably 60 nm or less. When it is thicker than 60 nm, the transmittance tends to be outside the preferable range. The first metal oxide layer 14 may be a stack of two or more metal oxide layers of different materials. For example, in this case, it is preferable to provide a low refractive index metal oxide layer on the transparent resin substrate 12 side and provide a high refractive index metal oxide layer on the metal layer 16 side. As a material of the low refractive index metal oxide layer, for example, one containing SiO ₂ as a main component is preferable. As a material of the high refractive index metal oxide layer, a material containing TiO ₂ in a material containing ZnO, In 2 O 3 or SnO 2 as a main component is preferable.

The metal layer 16 is provided to control the transmittance and the resistance value, and is made of a silver alloy containing silver as a main component. The metal layer 16 made of sufficiently thin silver (Ag) has high transmittance in the visible light region and high conductivity, but when the metal layer 16 is composed only of silver, under high temperature and high humidity Corrosion and aggregation are significant. Therefore, it is possible to improve the corrosion resistance without impairing the high transmittance and the low resistance by making the metal layer 16 a silver alloy containing silver as a main component and adding a few at% of additives. The material of the additive is not particularly limited, but Pd, Nd, Cu, Bi, Sb, In, Sn, Mg and the like are preferable. The additive amount is preferably 0.3 at% to 2 at%, and if less than 0.3 at%, it is difficult to obtain the effect of improving the corrosion resistance, and if it is more than 2 at%, the transmittance is reduced and the surface resistance is deteriorated. Unfavorable because there is a tendency. The film thickness of the metal layer 16 from which a high transmittance of 85% or more at a wavelength of 555 nm of light and a low surface resistance value of 50 Ω / □ or less is obtained is 6 nm or more and 12 nm or less. When the thickness is smaller than 6 nm, the surface resistance increases, and when the thickness is larger than 12 nm, the transmittance decreases.
The metal layer 16 can be formed by a vacuum deposition method such as a vacuum deposition method, a sputtering method, an ion plating method, or a CVD method. Among these, the sputtering method is preferable in that the film formation chamber can be miniaturized and the film formation rate is high. The sputtering method includes DC magnetron sputtering. A metal target can be used as a target.

The Si interface layer 20 is mainly composed of Si. By providing the Si interface layer 20, it is possible to achieve both high transmittance and low resistance. The Si interface layer 20 is formed of a film made of metal Si. The Si interface layer 20 may contain an additive of 0.5 wt% or less in addition to metal Si.
Boron (B) is preferred as the additive. The Si interface layer 20 may be provided by DC sputtering using a target of Si. The first metal oxide layer 14, the metal layer 16, the second metal oxide layer 18, and the Si interface layer 20 can be stacked successively by sputtering. By adding 0.5 wt% or less of boron to a Si target, DC sputtering of the Si interface layer 20 can be stably performed. If a Si target doped with boron of more than 0.5 wt% is used, the bulk resistance of the target is increased, making stable DC sputtering difficult. The film thickness of the Si interface layer 20 from which a high transmittance of 85% or more at a wavelength of 555 nm of light and a low surface resistance value of 50 Ω / □ or less is obtained is 0.5 nm or more and 1.5 nm or less. When the thickness is smaller than 0.5 nm or larger than 1.5 nm, the transmittance decreases. Si is a semiconductor metal, and the Si interface layer 20 is not a transparent film and absorbs light. The shorter the wavelength of light, the higher the degree of light absorption and the lower the transmittance. However, by providing the Si interface layer 20 in contact with the metal layer 16, it is possible to improve the transmittance as the laminated transparent conductive film.
One of the possible reasons is the reflectance reduction effect (anti-reflection effect) due to minute unevenness. The ultra-thin Si interface layer 20 is presumed to have an island-like structure instead of a continuous film. This island-like structure forms minute unevenness and reduces the change in refractive index by suppressing the change in the interface between the first metal oxide layer 14 and / or the second metal oxide layer 18 and the metal layer 16, It is inferred that the reflectivity at these interfaces is reduced, as a result of which the transmission is improved. Another possible reason is the change of optical constants (refractive index, extinction coefficient). The optical constants of the first metal oxide layer 14 and the second metal oxide layer 18 and the metal layer 16 greatly differ. At these interfaces, the reflectance (transmittance) changes in accordance with the difference in optical constants. Since Si also has anti-metallic properties, it has an effect of alleviating this change in the optical constant, and it is presumed that the Si interface layer 20 reduces the reflectance and improves the transmittance.

The second metal oxide layer 18 is provided for maintaining conductivity, adjusting optical properties and protecting the metal layer 16, and the material is not particularly limited, and Ti, Zr, Hf, Ta, Si, For example, a composite containing an oxide of at least one metal selected from Al, Mg, Y, Ce, Zn, In, Cr, Nb, Sn, Ga, Sb and the like is used. The composite is preferably composed of a material based on ZnO, In ₂ O ₃ or SnO ₂ . Here, the main component means that the molar ratio in the whole is 50% or more. This makes it easy to maintain the conductivity of the laminated transparent conductive film.
The film thickness of the second metal oxide layer 18 is preferably 20 nm or more and 60 nm or less. If it is thinner than 20 nm, or thicker than 60 nm, high transmittance tends to be difficult to obtain.

  EXAMPLES The present invention will be more specifically described below with reference to examples, but the present invention is not limited to these examples.

[Experimental Example 1]
Examples 1 to 3 and Comparative Examples 1 and 2

  In Examples 1 to 3, a laminated transparent conductive film as shown in FIG. 1 which is one structural example of the present invention was formed.

  In the laminated transparent conductive film of Example 1, a first metal oxide layer, a metal layer, a Si interface layer, and a second metal oxide layer are sequentially provided on a transparent resin substrate by DC magnetron sputtering. Was created. The Si interface layer was provided between the metal layer and the second metal oxide layer.

As a transparent resin substrate, a polyethylene terephthalate film having a thickness of 100 μm was used. The first metal oxide layer is 50 nm thick Ga ₂ O ₃ -ZnO (Ga ₂ O ₃ : ZnO = 2: 98 (mol%)), and the metal layer is 7 nm thick AgNdCu (Ag: Nd: Cu = 98.0: 0.5: 1.5 (at% )), Si interface layer having a thickness of 0.5nm Si, _Ga 2 _O 3 of the second metal oxide layer has a thickness 50 nm -ZnO (Ga ₂ A laminated transparent conductive film of O ₃ : ZnO = 2: 98 (mol%) was produced.

The first and second metal oxide layers were sputtered using a mixed gas of O ₂ / Ar = 2%, and the metal layer and the Si interface layer were sputtered using only Ar gas.

  The laminated transparent conductive film of Comparative Example 1 was formed in the same manner as Example 1 except that the Si interface layer was not provided. The laminated transparent conductive films of Examples 2 and 3 and Comparative Example 2 were the same as in Example 1 except that the film thickness of the Si interface layer of Example 1 was changed as shown in Table 1. .

[Experimental Example 2]
Examples 4 to 6 and Comparative Example 3
In Examples 4 to 6, a laminated transparent conductive film as shown in FIG. 2 which is another structural example of the present invention was formed.

  In the laminated transparent conductive film of Example 4, a first metal oxide layer, a Si interface layer, a metal layer, and a second metal oxide layer are sequentially provided on a transparent resin substrate by DC magnetron sputtering. Was created. The Si interface layer was provided between the first metal oxide layer and the metal layer.

  A laminated transparent conductive film was produced in the same manner as in Example 1 except that the Si interface layer was provided between the first metal oxide layer and the metal layer.

  In the laminated transparent conductive films of Examples 5 and 6 and Comparative Example 3, the Si interface layer is provided between the first metal oxide layer and the metal layer, and the film thickness of the Si interface layer is shown in Table 1 The other modifications were made in the same manner as in Example 1.

[Experimental Example 3]
Examples 7-9 and Comparative Example 4
In Examples 7 to 9, a laminated transparent conductive film as shown in FIG. 3 which is another structural example of the present invention was formed.

  The multilayer transparent conductive film of Example 7 was obtained by DC magnetron sputtering on a transparent resin substrate to form a first metal oxide layer, a Si interface layer, a metal layer, a Si interface layer, and a second metal oxide. Layers were created sequentially. The Si interface layer was provided between the metal layer and the second metal oxide layer, and between the first metal oxide layer and the metal layer.

  A laminated transparent conductive layer was prepared in the same manner as in Example 1, except that the Si interface layer was provided between the metal layer and the second metal oxide layer and between the first metal oxide layer and the metal layer. The membrane was made.

  The laminated transparent conductive films of Examples 8 and 9 and Comparative Example 4 have the Si interface layer between the metal layer and the second metal oxide layer, and between the first metal oxide layer and the metal layer. Furthermore, the film thickness of the Si interface layer was changed as shown in Table 1, and the other parts were prepared in the same manner as in Example 1.

[Experimental Example 4]
Comparative Examples 5 to 9
The laminated transparent conductive films of Comparative Examples 5 to 7 were prepared by replacing the Si interface layer of Example 1 with the SiO ₂ interface layer and setting the film thickness of the SiO ₂ interface layer as shown in Table 1.

The SiO ₂ interface layer was provided by sputtering using a Si target and using a mixed gas of O ₂ / Ar = 75%.

  The laminated transparent conductive films of Comparative Examples 8 and 9 were prepared in the same manner as in Example 1 except that Si was not used as the material of the Si interface layer, and the materials were changed to different materials and interface layers were provided.

  Each interface layer was provided with Ta and Cu with a film thickness of 0.5 nm as shown in Table 1. Each of these interface layers was provided by sputtering using an Ar gas using a Ta target and a Cu target.

  The transmittance | permeability in wavelength 555 nm of light was measured using the spectrophotometer made by Shimadzu Corp. MPC-3100 about the above laminated transparent conductive films. Moreover, the measurement of surface resistance value was performed using Mitsubishi Chemical four terminal resistivity meter Loresta GP. The results are shown in Table 1. The transmittance of light at a wavelength of 555 nm was 85% or more. The surface resistance value was 50 Ω / □ or less.

As shown in Table 1, in the laminated transparent conductive films of Examples 1 to 9, satisfactory values were obtained with a transmittance of 85% or more at a light wavelength of 555 nm and a surface resistance of 50 Ω / □ or less. It was obtained. In Comparative Example 1 in which the Si interface layer is not provided and in the laminated transparent conductive films of Comparative Examples 2 to 4 in which the film thickness of the Si interface layer is out of the range of 0.5 nm or more and 1.5 nm or less, The transmittance at a wavelength of 555 nm was less than 85%. Moreover, in the laminated transparent conductive films of Comparative Examples 5 to 7 in which the material of the Si interface layer is changed to the SiO ₂ interface layer, the transmittance of light at the wavelength of 555 nm is greatly reduced and does not reach 85% at all. The conductivity was lost, and the surface resistance value could not be measured. Further, in the laminated transparent conductive films of Comparative Examples 8 and 9 in which the interface layer made of Ta or Cu is provided, the transmittance of light at the wavelength of 555 nm is further lowered than in the case where the interface layer is not provided, and 85% or more is obtained. I could not.

[Experimental Example 5]
Examples 10 to 12 and Comparative Examples 10 to 12
The laminated transparent conductive films of Examples 10 to 12 and Comparative Examples 10 to 12 of the present invention are the same as in Example 1 except that the film thickness of the metal layer is changed as shown in Table 2. Created.

  The transmittance of the light at a wavelength of 555 nm and the surface resistance were also measured in the same manner as in Example 1 for these. The results are shown in Table 2.

  As shown in Table 2, in Examples 10 to 12 where the film thickness of the metal layer is in the range of 6 to 12 nm, the light transmittance at a wavelength of 555 nm is 85% or more, and the surface resistance is 50 Ω / sq or less was gotten. In Comparative Examples 10 to 12 in which the film thickness of the metal layer is outside the range of 6 to 12 nm, a laminated transparent conductive film satisfying both the high transmittance and the low surface resistance at the wavelength of 555 nm of light was not obtained.

  The laminated transparent conductive film of the present invention has a feature that it can be made lightweight and flexible since it is possible to use a resin film for the substrate while having high transmittance and low surface resistance. Therefore, it is suitable as a transparent conductive film used for a large sized touch panel, and it is possible to use it also as a transparent electrode for flexible organic EL lighting besides it.

12 Transparent resin substrate 14 First metal oxide layer 16 Metal layer 18 Second metal oxide layer 20 Si interface layer

Claims (1)

Having a first metal oxide layer, a metal layer, and a second metal oxide layer in this order on a transparent resin substrate,
A Si interfacial layer is provided at least one of between the first metal oxide layer and the metal layer, and between the metal layer and the second metal oxide layer,
The metal layer is a silver alloy having a thickness mainly composed of 12nm or less silver than 6 nm, the thickness of the Si interface layer Ri der least 1.5nm below 0.5 nm,
The Si interface layer comprises boron, and the multilayer transparent conductive film that boron content of the Si interface layer is characterized der Rukoto less 0.5 wt%.

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