CN107250959B - Transparent conductive substrate and transparent laminated structure - Google Patents

Abstract

The transparent conductive substrate of the present invention includes a transparent substrate and a structure in which a metal film, an intermediate film that is an oxide film containing molybdenum (Mo), and a transparent conductive film are sequentially stacked on one surface of the transparent substrate. In the structure, the average reflectance with respect to incident light in the visible light region is 10% or less, or the reflectance with respect to incident light having a wavelength of 550nm is 5% or less.

Description

Transparent conductive substrate and transparent laminated structure

Technical Field

The present invention relates to a transparent conductive substrate and a transparent laminated structure suitable for use in a touch panel. More specifically, the present invention relates to a transparent conductive substrate and a transparent laminated structure in which sensor electrodes of a touch panel are not easily visible.

This application claims priority based on the application of patent application No. 2015-062735, japanese application, 3/25/2015, and the contents of which are incorporated herein by reference.

Background

Conventionally, Indium Tin Oxide (ITO) electrodes have been widely used as sensor electrodes of touch panels. However, in recent years, with the progress of higher definition and larger size of panels, it is necessary to increase the thickness of an electrode using ITO in order to ensure a required low resistance value. Therefore, another factor that is also required as the performance of the sensor electrode, namely, permeability, has to be sacrificed.

On the other hand, conventionally, an electromagnetic wave shielding film of a plasma display panel has been used in a structure in which fine lines of metal members are arranged in a grid pattern on an insulating transparent substrate made of glass or the like and a transparent conductive film made of ITO or the like (hereinafter, referred to as a metal grid pattern) (for example, patent document 1). Further, application of thin wires of the metal member as sensor electrodes of a touch panel has been studied. In the metal mesh system, copper (Cu) is often used as a material of a common metal mesh. However, a metal film such as Cu has a property of easily reflecting light (high reflectance). Therefore, when Cu is used as a material of the sensor electrode of the touch panel, the Cu reflects extraneous light, and the reflected light is recognized by an observer (a user of the touch panel, hereinafter referred to as an observer). When such reflected light is mixed in the display image of the touch panel, the quality of the display image seen from the observer may be affected as a result. As a measure for suppressing the deterioration of the image quality of the touch panel due to the light reflection of the metal film, a thinning process of the metal film pattern and a process of blackening the surface of the metal film have been studied intensively (for example, patent document 2).

Fig. 8A to 8D are views showing an example of a structure in which a metal mesh is formed on a transparent substrate, fig. 8A is a plan view showing the whole, fig. 8B is an enlarged view of a region P5, and fig. 8C and 8D are cross-sectional views taken along line Z-Z in fig. 8B. In fig. 8A to 8D, reference numeral 501 denotes a transparent base material (transparent base), and reference numeral 502 denotes a metal film.

In order to produce the metal mesh structure shown in fig. 8A to 8D, first, a metal film 502F (502) made of Cu is formed over the entire surface of a transparent substrate 501F (501) [ fig. 8D ]. Then, the metal film 502F is etched using a mask not shown to form a mesh-like metal film, and then the surface of the metal film is oxidized to obtain the structure shown in fig. 8C.

That is, in the metal mesh structure shown in fig. 8A to 8D, a mesh-shaped Cu electrode 502 is disposed on a glass substrate 501E. The Cu electrode 502 is composed of a portion (metal portion) 502Ea having characteristics of a metal film formed at the time of film formation of the Cu electrode, and a portion (blackened portion) 502Eb which is blackened by oxidation treatment of the surface of the Cu electrode. In fig. 8A, a surface 502ET of the Cu electrode 502 in a grid pattern is a blackened portion 502 Eb. The portion corresponding to the opening of the mesh is the surface 501ET of the glass substrate. This makes it possible to suppress reflected light from being recognized by the observer while securing conductivity in the mesh-shaped Cu electrode 502.

However, since Cu has a property of being easily oxidized, etc., in the structure shown in fig. 8C, the oxidation state tends to be easily changed with time in the vicinity of the interface between the metal portion 502Ea and the blackened portion 502 Eb. That is, in the Cu electrode 502, the ratio of the metal portion 502Ea to the blackened portion 502Eb changes, and thus the conventional metal mesh structure (Cu electrode 502) has a problem that the characteristics (resistivity) as a conductive film are unstable. Further, since the oxidation state of the surface of the metal mesh is likely to change, there is a problem that the degree of blackening is also likely to change, and the color tone of the surface of the metal mesh is likely to change.

When the metal mesh structure is applied to a sensor electrode of a touch panel, it is necessary to connect an FPC (Flexible Printed Circuit) for connecting an electric signal detected by the sensor electrode to an external driving Circuit to the sensor electrode. However, in the conventional metal mesh structure (Cu electrode 502), since the oxide film (blackened portion 502Eb) of Cu is exposed on the surface, a process of removing a part of the oxide film and exposing the metal portion 502Ea inside is required to electrically connect the FPC and the sensor electrode.

Therefore, development of a transparent conductive substrate having a metal mesh structure that can obtain stable conductivity, suppress reflected light from being recognized by an observer, and can easily electrically connect an FPC and a sensor electrode has been desired.

Patent document 1: japanese patent laid-open publication No. 2006-139277

Patent document 2: japanese patent laid-open publication No. 2013-206315

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a transparent conductive substrate and a transparent laminated structure having a metal mesh structure which can obtain stable conductivity, can suppress reflected light from being recognized by an observer, and has excellent connectivity with an external circuit.

A transparent conductive substrate according to a first aspect of the present invention includes a transparent substrate and a structure in which a metal film, an intermediate film that is an oxide film containing molybdenum (Mo), and a transparent conductive film are sequentially stacked on one surface of the transparent substrate. In the structure, the average reflectance with respect to incident light in a visible light region (a wavelength region of 380nm to 780nm) is 10% or less.

A transparent conductive substrate according to a second aspect of the present invention includes a transparent substrate and a structure in which a metal film, an intermediate film that is an oxide film containing molybdenum (Mo), and a transparent conductive film are sequentially stacked on one surface of the transparent substrate. In the structure, the reflectance with respect to incident light having a wavelength of 550nm is 5% or less.

In the transparent conductive substrate according to the first and second aspects of the present invention, the interlayer film may have a resistivity (μ Ω · cm) of 1.8 × 10⁸The following.

In the transparent conductive substrate according to the first and second aspects of the present invention, the thickness (nm) of the transparent conductive film may be in a range of 10 to 50 inclusive.

In the transparent conductive substrate according to the first and second aspects of the present invention, the color tone of the structure can be adjusted by controlling at least one of the resistivity of the intermediate film and the film thickness of the transparent conductive film.

In the transparent conductive substrate according to the first and second aspects of the present invention, a structure in which the metal film, the intermediate film, and the transparent conductive film are sequentially laminated on the one surface of the transparent base body is etched to have a desired pattern.

A transparent laminated structure according to a third aspect of the present invention includes a metal film, an intermediate film provided on the metal film and serving as an oxide film containing molybdenum (Mo), and a transparent conductive film provided on the intermediate film. In the transparent laminated structure, the average reflectance with respect to incident light in the visible light region is 10% or less.

The transparent conductive substrate according to the above aspect of the present invention includes a structure in which a metal film, an intermediate film, and a transparent conductive film are sequentially stacked on one surface of the transparent substrate, and the intermediate film is formed of an oxide film containing molybdenum (Mo). As described above, since the transparent conductive substrate according to the above-described aspect of the present invention has a laminated structure, an interface exists between the metal film and the interlayer film, and the possibility that oxygen contained in the interlayer film enters the metal film through the interface is extremely low compared to a conventional structure (a structure in which the surface of the metal film is oxidized). Further, since the color tone is adjusted by the intermediate film and the transparent conductive film independently of the metal film, the color tone (reflection characteristic of the structure) can be stably maintained as compared with a conventional structure in which the surface of the metal film is blackened by oxidation treatment.

Here, the structure has a low reflection structure, and can be adjusted to a desired color tone and also ensure conductivity as an electrode by satisfying a condition that the average reflectance of incident light in the visible light region (wavelength region from 380nm to 780nm) is 10% or less, or particularly a condition that the reflectance of light having a wavelength of 550nm, which is most clearly visible to the human eye, is 5% or less. In particular, in the structure, by controlling the amount of oxygen contained in the intermediate film and the thickness of the transparent conductive film, both low resistance and high transmittance of the structure can be achieved.

Accordingly, the above aspect of the present invention contributes to providing a transparent conductive substrate having a metal mesh structure that can obtain stable conductivity and suppress reflected light from being recognized by an observer.

Drawings

Fig. 1A is a plan view schematically showing an example of a transparent conductive substrate according to an embodiment of the present invention.

Fig. 1B is a diagram schematically showing an example of the transparent conductive substrate according to the embodiment of the present invention, and is an enlarged plan view showing a region P1 in fig. 1A.

Fig. 1C is a cross-sectional view schematically showing an example of a transparent conductive substrate according to an embodiment of the present invention, and is a view taken along line a-a in fig. 1B.

Fig. 1D is a cross-sectional view schematically showing an example of a transparent conductive substrate according to an embodiment of the present invention, and is a view taken along line a-a in fig. 1B.

Fig. 2A is a cross-sectional view schematically showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 2B is a sectional view schematically showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 2C is a sectional view schematically showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 2D is a sectional view schematically showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 2E is a sectional view schematically showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 3 is a graph showing the reflectance of the structure of the transparent conductive substrate.

Fig. 4 is a graph showing the resistivity of an interlayer film forming the structure.

Fig. 5 is a schematic view showing an example of an apparatus for manufacturing a transparent conductive substrate according to an embodiment of the present invention.

Fig. 6 is a schematic view showing another example of the apparatus for manufacturing a transparent conductive substrate according to the embodiment of the present invention.

Fig. 7A is a cross-sectional view schematically showing an example of a solar cell according to modification 1 of the embodiment of the present invention.

Fig. 7B is an enlarged cross-sectional view schematically showing an example of a solar cell according to modification 1 of the embodiment of the present invention.

Fig. 7C is an enlarged cross-sectional view schematically showing an example of a solar cell according to modification 2 of the embodiment of the present invention.

Fig. 8A is a plan view schematically showing an example of a conventional transparent conductive substrate.

Fig. 8B is a diagram schematically illustrating an example of a conventional transparent conductive substrate, and is an enlarged plan view illustrating a region P5 in fig. 8A.

Fig. 8C is a cross-sectional view schematically showing an example of a conventional transparent conductive substrate, and is a view taken along the line Z-Z in fig. 8B.

Fig. 8D is a cross-sectional view schematically showing an example of a conventional transparent conductive substrate, and is a view taken along the line Z-Z in fig. 8B.

Fig. 9 is a cross-sectional view schematically showing an example of the structure of a conventional solar cell.

Detailed Description

Hereinafter, a transparent conductive substrate according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1A to 1D are schematic views showing a transparent conductive substrate according to the present embodiment, fig. 1A is a plan view of the whole, fig. 1B is an enlarged plan view of a region P1, and fig. 1C and 1D are cross-sectional views taken along line a-a of fig. 1B. In particular, fig. 1C shows a cross-sectional view of the transparent conductive substrate after etching, and fig. 1D shows a cross-sectional view of the transparent conductive substrate before etching.

The transparent conductive substrate of the present embodiment is used for a capacitive touch panel or the like that is disposed on a display panel such as a liquid crystal or an organic EL (organic electroluminescence) panel and operates by touching an operation surface.

As shown in fig. 1A to 1D, the transparent conductive substrate S1E (S1) includes a structure (transparent laminated structure) in which a metal film 102E (102), an interlayer film 103E (103), and a transparent conductive film 104E (104) are laminated in this order on one surface 101ET of an insulating transparent base 101E (101) made of glass or the like.

Fig. 1A to 1D show an example in which the structure is formed in a grid shape, and as shown in fig. 1B, the structure arranged on the transparent base 101E (101), that is, all three layers of the metal film 102E, the intermediate film 103E, and the transparent conductive film 104E are formed on the same side surface, and the structure is formed in a grid shape. The shape of the side surface of the structure is not limited to a structure in which all three layers form the same side surface, and an uneven structure may be formed on the side surface by conditions in an etching step described later. The metal film 102E is electrically connected to a driver circuit through an intermediate film 103E and a transparent conductive film 104E laminated on the metal film 102E, and further through an FPC connected to the transparent conductive film 104E.

In the present invention, the interlayer film 103 is provided so as to be sandwiched between the metal film 102 and the transparent conductive film 104 (the interlayer film 103 is omitted in fig. 1A and 1B). In the manufacturing method described later, the structures composed of these three layers are preferably etched all at once, and the respective films may be etched.

In the transparent conductive substrate of the present embodiment, as the transparent substrate 101, in addition to a substrate made of glass, resin substrates such as PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), COP (cyclic olefin polymer), PE (polyethylene), PMMA (Polymethyl methacrylate), and the like are also applicable.

The metal film 102 in the above structure is required to have excellent conductivity and high etching property.

Examples of the metal film member satisfying such conditions include Al, Al alloy, Mo alloy, Ti alloy, Cu, and Cu alloy. Among these, a metal film made of an (Al — Nd) alloy containing neodymium (Nd) in Al is preferable in terms of obtaining stable conductivity and weather resistance, and further, generation of a protrusion, which is a problem peculiar to Al, can be suppressed by addition of Nd, and thus, is preferable.

The intermediate film 103 in the above-described structure is arranged between the metal film 102 and the transparent conductive film 104, and therefore, it is required to have both conductivity that can ensure only conduction between the transparent conductive film and the metal film and low reflectance that is necessary to suppress reflected light from being recognized by an observer. Specifically, an oxide film containing molybdenum (Mo) is preferably used as the intermediate layer. This is because the good conductivity of molybdenum oxide effectively acts on the connection between the metal film and the transparent conductive film. Even when an alloy such as (Mo — Nb) containing niobium (Nb) in Mo is used, the addition of Nb to the metal film improves the weather resistance, and the same effect as that obtained when the alloy is not used can be obtained as a condition for obtaining low reflection.

In addition, the first and second substrates are,when an intermediate film is formed in a sputtering apparatus described later, the intermediate film is formed except for (Ar + O)₂) Mixed gas, a small amount of N may be added to adjust the etching rate of the intermediate film₂. In this case, the interlayer film formed contains a small amount of nitrogen, but the function of the interlayer film as an oxide film is not impaired by this addition.

The transparent conductive film 104 In the above-described structure is not particularly limited, and known transparent conductive materials can be used, and examples thereof include ITO (Indium Tin Oxide doped with Tin), AZO (ZnO doped with Al), BZO (ZnO doped with B), and In₂O₃-ZnO、In₂O₃-TiO₂And the like. Among them, In is preferably contained₂O₃. By containing In₂O₃The transparent conductive film can be dissolved in acid and has alkali resistance while maintaining good conductivity. The transparent conductive film having such characteristics is suitable for a photolithography process.

The structure composed of the three layers, i.e., the metal film 102, the intermediate film 103, and the transparent conductive film 104, has an average reflectance of 10% or less with respect to incident light in the visible light region (wavelength range of 380 to 780[ nm ]), and thus effectively functions as a low reflection structure. Therefore, the color tone of the surface of the metal mesh can be adjusted. Alternatively, the reflectance of incident light having a wavelength of 550[ nm ] representing the visible light region is defined to be 5% or less, and the function as a low reflection structure can be secured.

In the visible region, light of wavelength 550[ nm ] is the most visible light by the human eye. Therefore, in the present embodiment, the reflectance of the transparent laminated structure provided on the transparent conductive substrate is adjusted so that the reflectance of light having a wavelength of 550[ nm ] incident on the structure (transparent laminated structure) and reflected therefrom is 5% or less. Thus, even when the reflectance in the upper limit region (around 380 nm) and the reflectance in the lower limit region (around 780nm) in the visible light region are rapidly increased, the transparent laminated structure and the transparent conductive substrate provided with the transparent laminated structure can effectively function as a low reflection structure.

In addition, the definition of the average reflectance in the embodiment of the present invention is as follows: basically, the total of the reflectance values obtained at a distance of 1nm in the visible light region (wavelength region of 380 to 780[ nm ]), and the value obtained by dividing the total by the number of dots of the data is obtained. However, for the sake of simplicity, the reflectance obtained at a distance of 50nm in the visible light region (wavelength region of 380 to 780[ nm ]) may be defined as a total value, and the total value may be divided by the number of dots in the total data.

Fig. 3 is a graph showing the reflectance of the structure (transparent laminated structure) of the transparent conductive substrate according to the embodiment of the present invention.

In fig. 3, the horizontal axis represents the wavelength of incident light, and the vertical axis represents the reflectance. The solid line in fig. 3 shows the result of the transparent laminated structure of the example having the three-layer laminated structure of the embodiment of the present invention. The dotted line in fig. 3 shows the result of the transparent conductive substrate of the comparative example.

The transparent conductive substrate of the comparative example is different from the transparent conductive substrate having the three-layer structure of the example, and has a structure in which no intermediate film and no transparent conductive film are provided, that is, a transparent conductive substrate in which only a metal film is formed on a base.

In the measurement of reflectance shown in fig. 3, in both the examples and the comparative examples, the measurement device was disposed on the side opposite to the position where the substrate was disposed, and the amount of reflected light was measured to measure reflectance. Specifically, in the case of the embodiment, the measurement device is disposed at a position facing the transparent conductive film, and the amount of reflected light is measured to measure the reflectance. In the case of the comparative example, the measurement device was disposed at a position facing the metal film, and the amount of reflected light was measured to measure the reflectance. The obtained reflectance value indicates the reflectance due to the metal film, the interlayer film, and the transparent conductive film in the case of the example, and indicates the reflectance due to only the metal film in the case of the comparative example.

In the structure of the comparative example, a reflectance of almost 90% was observed over the entire visible light region (wavelength range of 380 to 780[ nm ]), and it was found that the pattern of the metal mesh was recognizable. On the other hand, in the structure of the embodiment of the present invention, it was confirmed that the average reflectance in the visible light region (wavelength region 380 to 780[ nm ]) was 10% or less (6.8% as calculated by the distance of 1nm and 8.8% as calculated by the distance of 50 nm), and the low reflectance condition was sufficiently satisfied. In addition, in the embodiment, the reflectance of incident light of 550[ nm ] was 1.9%.

Fig. 4 is a graph showing the resistivity of the intermediate film in the transparent conductive substrate according to the embodiment of the present invention. In FIG. 4, the horizontal axis represents the flow rate of oxygen gas [ sccm ] during film formation]The vertical axis represents the resistivity of the interlayer film [ 1X 10 ]ⁿμΩ·cm]. The numbers shown on the vertical axis are n times (1 × 10)ⁿ) "n" in (1). In fig. 4, symbol ". smallcircle" indicates the case of blackening, symbol "Δ" indicates the case of transparency, and symbol "diamond" indicates the case of metallic luster.

The following points can be clarified from the results shown in fig. 4.

(1) By adjusting the amount of oxygen contained in the intermediate film, the color tone of the intermediate film can be controlled.

(2) Particularly, the resistivity of the interlayer film 103 is set to 1.8 × 10⁸[μΩ·cm]In the following, a low reflection structure can be obtained, and the color tone of the intermediate film can be controlled within this range.

(3) Specifically, as the resistivity decreases, the degree of coloring can be increased. In other words, as the resistivity decreased, a phenomenon that the color tone of the interlayer film became darker could be confirmed.

In the three-layer structure according to the embodiment of the present invention, the intermediate film 103 is actually thin, and the conductivity of the metal film 102 mainly contributes to the resistance value of the entire three-layer structure. If the interlayer film 103 has conductivity that functions as a film for electrically connecting the metal film 102 and the transparent conductive film 104, there is no problem, and if the interlayer film 103 has a resistance value of 1.8 × 10⁸[μΩ·cm]Hereinafter, the function of the interlayer film 103 can be sufficiently obtained.

The horizontal axis in fig. 4 represents the amount of oxygen added during the formation of the interlayer film. ByAs can be seen from fig. 4, the resistivity of the interlayer film increased with the amount of oxygen added, and the change in the color tone of the interlayer film was observed. Molybdenum oxide is known to change color tone due to a difference in oxidation number. In particular, MoO₂And Mo₂O₅There is a tendency to form a film which is not transparent but has a grey brown or black hue. That is, it is considered that the interlayer film having the resistivity in the above range has, in particular, MoO among the oxide films containing molybdenum₂Or Mo₂O₅Or a composition ratio in the vicinity thereof.

In the case of the three-layer structure, the transparent conductive film is disposed on the intermediate film, and the change in color tone of the intermediate film can be promoted by changing the film thickness of the transparent conductive film. Therefore, the structure according to the embodiment of the present invention can adjust the color tone of the structure by controlling at least one of the resistivity of the intermediate film and the film thickness of the transparent conductive film.

The film thickness of such a transparent conductive film depends on the film thickness, material, and the like of the metal film and the intermediate film, but is preferably 10nm to 50nm as a range in which electrical conductivity can be secured and optical adjustment between the lower layer (layer located below the transparent conductive film) and the transparent conductive film can be performed.

In addition to the three layers described above, a desired functional film may be formed on the upper and lower interfaces of the metal film 102 as needed. That is, a functional film for the purpose of barrier property or adhesion, for example, a Mo film, a Ti film, or the like may be provided between the transparent substrate 101 and the metal film 102. Alternatively, for example, a Mo film, a Ti film, or the like may be provided between the metal film 102 and the interlayer film 103 as a functional film for suppressing the generation of Al projections contained in the metal film 102.

Fig. 2A to 2D are schematic views showing a method for manufacturing a transparent conductive substrate according to an embodiment of the present invention, and particularly, specifically, show an etching step for patterning a structure composed of three layers (particularly, a case where three layers are collectively etched). A method for manufacturing the transparent conductive substrate having the above-described structure will be described below with reference to fig. 2A to 2D.

Step 1: a sputtering apparatus (for example, fig. 5) described later is used to form "a transparent conductive substrate S1F in which a metal film 102F, an intermediate film 103F, and a transparent conductive film 104F are sequentially stacked on a transparent base 101F", and then the transparent conductive substrate S1F is placed in an atmosphere (fig. 2A).

And a step 2: in order to etch the metal film 102F, the intermediate film 103F, and the transparent conductive film 104F together, a resist layer R patterned in a predetermined shape is formed on the surface of the transparent conductive film 104F (fig. 2B). Hereinafter, the transparent conductive substrate S1F on which the resist layer R is formed is referred to as a target object.

Step 3: the etching liquid EL is sprayed on the surface of the object S1m1 on which the etching resist layer R is formed, and the portion of the transparent conductive film 104F exposed from the etching resist layer R is etched (fig. 2C). As the etching liquid EL, a solution capable of etching the structure composed of three layers is selected, whereby the three layers can be collectively etched. Instead of spraying the etching liquid EL, a method of immersing the object S1m1 in the etching liquid may be used.

And step 4: after a predetermined time has elapsed, the etching is stopped (fig. 2D). The spraying of the object S1m2 is stopped, or the object S1m2 is pulled up from the etching solution. Fig. 2D shows a case where etching is stopped. At this time, the transparent substrate 101m2 is exposed in the region where the etching resist layer is not disposed.

Step 5: after the object S1m2 is cleaned and the etching solution is removed, the etching resist layer R is removed, whereby the transparent conductive substrate S1E according to the embodiment of the present invention can be obtained (S1).

That is, the method for manufacturing a transparent conductive substrate according to the embodiment of the present invention includes the steps of: a mask having a desired void pattern (for example, a mesh pattern) is provided on the upper surface of the transparent conductive film 104, and the three layers (the metal film 102F, the intermediate film 103F, and the transparent conductive film 104F) are etched through the voids. Thus, the three layers (metal film 102F, intermediate film 103F, and transparent conductive film 104F) can be etched in a desired pattern until the transparent base 101 is exposed through the gaps provided in the mask. Therefore, according to the embodiments of the present invention, a method for manufacturing a transparent conductive substrate having both conductivity and a low reflection condition can be provided.

In addition, although the case where three layers are collectively etched is described here in particular, the etching may be performed individually for each layer depending on the material and film thickness selected for the metal film, the intermediate film, and the transparent conductive film. Further, although the patterning by wet etching is described, other patterning techniques such as photolithography may be used.

< methods for producing Metal film, intermediate film and transparent conductive film >

A method for producing the transparent conductive substrate S1 prepared in the above step 1, that is, the transparent conductive substrate S1F in which the metal film (AlNd alloy film) 102F, the interlayer film (MoNb oxide film) 103F, and the transparent conductive film (ITO film) 104F are sequentially laminated on the transparent base (glass substrate) 101, will be described below.

As a manufacturing apparatus for forming a metal film, an intermediate film, and a transparent conductive film on a substrate 101 made of glass, a combined sputtering apparatus as shown in fig. 5 can be used.

In the manufacturing apparatus shown in fig. 5, the substrate 118a (corresponding to the base 101 made of a flexible member described above) is movable by a not-shown conveying apparatus inside the loading/unloading chamber (L/UL)111, the heating chamber (H)112, the first film forming chamber (S1)113, the first buffer chamber (B1)114, the second film forming chamber (S2)115, the second buffer chamber (B2)116, and the third film forming chamber (S3) 117.

Partition valves DV1 to DV7 are disposed between the chambers adjacent to each other. Further, a buffer chamber is disposed between the two film forming chambers. The manufacturing apparatus shown in fig. 5 is configured to maintain an atmosphere of independent film forming conditions in the first to third film forming spaces described later. However, in the case where the first to third film formation spaces described later are not affected by other film formation spaces (for example, a desired pressure difference means is disposed in the film formation spaces), the production apparatus may have a single film formation space without providing a partition valve or a buffer chamber.

First, the substrate 118A is transported from the loading/unloading chamber 111 in a reduced-pressure atmosphere to the heating chamber 112, and a desired heat treatment is performed. By this heat treatment, the substrate 118b is degassed and heated to a desired temperature. In addition, the heat treatment for degassing may be omitted depending on the material of the substrate used.

Then, the heat-treated substrate 118b is conveyed from the heating chamber 112 to the first film formation chamber 113, and is passed through the front surface of the target 113TG made of the base material of the metal film (i.e., the first film formation space sp1), whereby a metal film (AlNd alloy film) is formed on the substrate 118 c. At this time, Ar gas is supplied from the process gas supply source 113G to the first film formation space sp1, and a desired pressure is maintained by the exhaust device 113P. If necessary, a temperature adjusting device, not shown, may be provided to control the temperature of the substrate 118c during film formation. Reference numeral 113BP denotes a pad on which the target 113TG is placed, and 113D denotes a power supply which supplies a high voltage to the pad 113 BP.

Then, the substrate 118c on which the metal film is formed is conveyed from the first film formation chamber 113 to the first buffer chamber 114. The first buffer chamber 114 is disposed between the first film formation chamber 113 (first film formation space sp1) and a second film formation chamber 115 (second film formation space sp2) described later, and the internal space of the first buffer chamber 114 is maintained at a desired degree of vacuum by the exhaust device 114P. At the position α in the first buffer chamber 114, the substrate 118c on which the metal film is formed stays for a desired time, and the atmosphere in the first film formation space sp1 in the front stage and the atmosphere in the second film formation space sp2 in the rear stage are prevented from affecting each other.

Next, the substrate 118c on which the metal film is formed is transported from the first buffer chamber 114 to the second film formation chamber 115, and passes through the front surface of the target 115TG (i.e., the second film formation space sp2) made of the intermediate film base material, thereby forming an intermediate film (MoNb oxide film) on the metal film (AlNd alloy film) of the substrate 118 c. At this time, (Ar + O) is supplied from the process gas supply source 115G to the second film formation space sp2₂) The mixed gas is maintained at a desired pressure by the exhaust device 115P. If necessary, a temperature adjusting device, not shown, may be provided to control the temperature of the substrate 118c during film formation. A symbol 115BP denotes a pad on which the target 115TG is placed, and a symbol 115D denotes a power source which supplies a high voltage to the pad 115 BP.

Here, as the process gas, (Ar + O) is used₂) In the case of mixed gasesIt is illustrated, but a small amount of N may be added thereto₂. Thereby, the etching rate of the intermediate film can be adjusted. The addition is carried out within a range that does not impair the function of the intermediate film as an oxide film.

Then, the substrate 118d having the intermediate film laminated on the metal film is transferred from the second film formation chamber 115 to the second buffer chamber 116. The second buffer chamber 116 is disposed between the second film formation chamber 115 (second film formation space sp2) and a third film formation chamber 117 (third film formation space sp3) described later, and the internal space of the second buffer chamber 116 is maintained at a desired degree of vacuum by the exhaust device 116P. At the position β in the second buffer chamber 116, the substrate 118d on which the intermediate film is formed stays for a desired time, and the atmosphere in the second film formation space sp2 in the front stage and the atmosphere in the third film formation space sp3 in the rear stage are prevented from affecting each other.

Next, the substrate 118d having the intermediate film laminated on the metal film is transported from the second buffer chamber 116 to the third film forming chamber 117, and passes through the front surface of the target 117TG made of the base material of the transparent conductive film (i.e., the third film forming space sp3), thereby forming the transparent conductive film (ITO) on the intermediate film of the substrate 118 d. At this time, (Ar + O) is supplied from the process gas supply source 117G to the third film formation space sp3₂) The mixed gas is maintained at a desired pressure by the exhaust device 117P. If necessary, a temperature adjusting device, not shown, may be provided to control the temperature of the substrate 118d during film formation. Reference numeral 117BP denotes a pad on which the target 117TG is placed, and reference numeral 117D denotes a power supply which supplies a high voltage to the pad 117 BP.

Then, as shown by an arrow RT in fig. 5, the substrate 118 on which the metal film, the intermediate film, and the transparent conductive film are sequentially stacked is inverted (or reversed), transported from the third film formation chamber 117 to the loading/unloading chamber 111, and taken out from the manufacturing apparatus to the outside (atmosphere).

That is, the manufacturing apparatus shown in fig. 5 includes at least a first film formation space sp1 in which the metal film is formed, a second film formation space sp2 in which the intermediate film is formed, and a third film formation space sp3 in which the transparent conductive film is formed, and the second film formation space sp2 is disposed between the first film formation space sp1 and the third film formation space sp3 in the direction in which the substrate moves.

Next, the structure composed of the three layers (metal film 102F, intermediate film 103F, and transparent conductive film 104F) was subjected to a desired patterning through the above-described etching step, and the transparent conductive substrate according to the embodiment of the present invention was obtained.

Representative production conditions of the metal film, the intermediate film, and the transparent conductive film are shown in table 1. Table 2 shows typical processing conditions in the etching step in the case of forming a structure composed of three layers in a mesh shape (fig. 1A to 1D and fig. 2A to 2D).

[ Table 1]

Substrate	PET (125 μm thickness)
		Film-forming material (Metal film)	AlNd
Film Forming Material (intermediate film)	MoNb
		Film-forming material (transparent conductive film)	ITO (indium-tin oxide)
Membrane structure	substrate/Metal film (100 nm)/intermediate film (35 nm)/transparent conductive film (25nm)
		Film formation temperature	At room temperature
Input power (per unit area)	10W/cm2(Metal film) 2W/cm2(intermediate film) 2W/cm2(transparent conductive film)
		Film forming gas	Ar (metal film), Ar + O2(intermediate film, transparent conductive film)
Film forming pressure	0.5Pa (Metal film, intermediate film, transparent conductive film)

[ Table 2]

Etching solution	Phosphoric acid acetic acid solution
		Concentration of	Less than 80% of phosphoric acid, less than 5% of nitric acid, less than 10% of acetic acid and more than 5% of water
Temperature of	At room temperature
		Time of day	10 minutes

Under the conditions shown in tables 1 and 2, the transparent conductive substrate having the structure of three layers (metal film 102F/intermediate film 103F/transparent conductive film 104F) in a mesh shape shown in fig. 1A to 1D can be stably produced.

The apparatus for producing the metal film, the intermediate film, and the transparent conductive film shown in table 1 is not limited to the production apparatus shown in fig. 5, and for example, the transparent conductive substrate according to the embodiment of the present invention can be produced even when a multi-chamber type production apparatus shown in fig. 6 is used.

Fig. 6 is a schematic view showing another example of the apparatus for manufacturing the transparent conductive substrate according to the embodiment of the present invention. The manufacturing apparatus shown in fig. 6 corresponds to a case where each film formation step of the metal film, the intermediate film, and the transparent conductive film is performed in a separate film formation space chamber of each film formation chamber (chamber).

The transport path of the substrate made of glass in the case where each of the film forming steps of the metal film, the intermediate film, and the transparent conductive film is performed by using such a multi-chamber manufacturing apparatus will be described. First, a substrate is carried into the loading chamber (L)201 from the outside. Then, after the substrate is held in a load chamber in a reduced pressure state for a certain period of time, the substrate is conveyed to a heating chamber (H)202, and the substrate is subjected to heat treatment (degassing treatment) at a desired temperature.

Then, the substrate after the heat treatment is conveyed from the heating chamber (H)202 into the first film forming chamber (S1)203, and a metal film is formed in the first film forming space sp 1. Thereafter, the substrate on which the metal film is formed is transported from the first film formation chamber (S1)203 to the second film formation chamber (S2)204, and the intermediate film is formed in the second film formation space sp 2. Further, the substrate having the intermediate film formed on the metal film is transported from the second film forming chamber (S2)204 to the third film forming chamber (S3)205, and the transparent conductive film is formed in the third film forming space sp 3.

Next, the substrate having the intermediate film and the transparent conductive film formed on the metal film is transferred from the third film forming chamber (S3)205 to the unload chamber (UL)206, and after waiting for a predetermined time, the substrate is carried out from the unload chamber (UL)206 to the outside. As an apparatus for transferring the substrate between the chambers, a robot (not shown) provided in the transfer chamber (T)207 is used. In addition, all the chambers 201 to 206 including the transfer chamber (T)207 are in a reduced pressure state during the process treatment and the transportation of each chamber.

That is, the manufacturing apparatus shown in fig. 6 includes at least the first film formation space sp1 in which the metal film is formed, the second film formation space sp2 in which the intermediate film is formed, and the third film formation space sp3 in which the transparent conductive film is formed, and the second film formation space sp2 is disposed between the first film formation space sp1 and the third film formation space sp3 in the direction in which the substrate moves.

While the preferred embodiments of the present invention have been described above, it should be understood that these are exemplary of the present invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

For example, in the above-described embodiment, an example in which three layers constituting a transparent laminated structure are provided on a transparent substrate is described, but the present invention is not limited thereto. A transparent laminated structure may be provided on a member different from the transparent substrate of the above embodiment.

The following describes modifications of the embodiments of the present invention. In the modification, the description of the components corresponding to those in the above embodiment is omitted or simplified.

[ modification 1]

Fig. 7A is a cross-sectional view schematically showing an example of a solar cell to which the transparent laminated structure is applied. Fig. 7B is an enlarged sectional view schematically showing the structure of the transparent laminated structure of fig. 7A. Fig. 9 is a cross-sectional view schematically showing an example of the structure of a conventional solar cell.

As shown in fig. 9, a conventional solar cell 600 includes a monocrystalline silicon substrate 620 having a pn junction 630, a back surface electrode 610 provided on the back surface of the silicon substrate 620, finger electrodes 640 provided on the front surface of the silicon substrate 620, and bus bar electrodes 650 (bus bar wirings) provided on the finger electrodes 640.

The bus bar electrode 650 collects electrons generated by the power generation of the silicon substrate 620. In general, silver is used as a material of the bus bar electrode 650. However, since the external color of the solar cell 600 is a color close to black, the black color of the silicon substrate 620 has a large contrast with the silver-white color of the bus bar electrode 650, and there is a problem that the external design is poor.

On the other hand, the solar cell of modification 1 is applied with the above-described transparent laminated structure.

Specifically, as shown in fig. 7A, the solar cell 300 of modification 1 includes a single crystal silicon substrate 320 having a pn junction 330, a back surface electrode 310 provided on the back surface of the silicon substrate 320, finger electrodes 340 provided on the front surface of the silicon substrate 320, and bus bar electrodes 350 (bus bar wirings) provided on the finger electrodes 340 and each including a transparent laminated structure. Further, the finger electrodes 340 are provided on the pn junction 330, and the surfaces of the finger electrodes 340 are provided with antireflection films. Therefore, the bus bar electrode 350 is provided on the antireflection film of the finger electrode 340.

As shown in fig. 7B, the bus bar electrode 350 includes a metal film 351 provided on the finger electrode 340, an intermediate film 352 provided on the metal film 351, and a transparent conductive film 353 provided on the intermediate film 352. That is, the intermediate film 352 is sandwiched between the metal film 351 and the transparent conductive film 353.

The conductivity of the bus bar electrode 350 is obtained by the metal film 351. The intermediate film 352 is an oxide film containing molybdenum. By adjusting the oxidation degree and the film thickness of the transparent conductive film 353, the bus bar electrode 350 composed of a transparent laminated structure having a low reflectance can be realized.

According to the solar cell 300 of modification 1, not only the effects of the above-described embodiment can be obtained, but also the reflection light from the bus bar electrode can be reduced because the transparent laminated structure is applied to the bus bar electrode 350. Therefore, the problem of the conventional solar cell 600 that the silver white of the bus bar electrode 650 is contrasted with the black of the silicon substrate 620 can be solved.

[ modification 2]

Fig. 7C is an enlarged sectional view showing the finger electrode constituted by the transparent laminated structure. In modification 2, the same components as in modification 1 are denoted by the same reference numerals, and description thereof is omitted or simplified.

As shown in fig. 7C, the finger electrode 340 includes a metal film 341 provided on the pn junction 330, an intermediate film 342 provided on the metal film 341, and a transparent conductive film 343 provided on the intermediate film 342. That is, the intermediate film 342 is sandwiched between the metal film 341 and the transparent conductive film 343.

In the finger electrode 340 having such a transparent laminated structure, in order to obtain conductivity between the finger electrode 340 and the bus bar electrode 350, a part of the finger electrode 340 (the intermediate film 342 and the transparent conductive film 343) may be partially removed, and the finger electrode 340 and the bus bar electrode 350 may be electrically connected.

According to the solar cell 300 of modification example 2, not only the effects of the above-described embodiment can be obtained, but also the transparent laminated structure is applied to the finger electrodes 340, and thus reflected light from the finger electrodes can be reduced.

[ modification 3]

The transparent laminated structure described above can be applied to a light-shielding film for optical devices.

In general, in digital optical devices such as digital cameras, it is known to form a functional film having low reflectivity and excellent electrical conductivity on the surface of a member constituting an internal mechanism of the optical device (for example, JP 2008-a 281977).

The transparent laminated structure of the above embodiment can be used as such a functional film. In this case, a transparent laminated structure is formed on both the front and back surfaces of a base material such as a resin film. The transparent laminated structure may be directly formed on the surface of a member processed into a shutter blade, a diaphragm blade, or the like. Further, since the entire surface of the member constituting the optical device needs to have the low reflection structure, the low reflection structure may be formed entirely on the surface of the member constituting the optical device. In this case, the substrate may be a transparent substrate or a colored substrate.

In the transparent laminated structure of modification 3, the low reflection structure can be realized by controlling the oxidation degree and the film thickness of the intermediate film and the transparent conductive film. Further, since the transparent laminated structure has a metal film, conductivity can be obtained, and electrification of members constituting an internal mechanism of an optical device can be prevented.

The present invention can be widely applied to transparent conductive substrates. The transparent conductive substrate of the present invention is suitable for high-quality display screens and the like requiring excellent visibility.

Description of the symbols

P1 region, S1(S1E, S1F) transparent conductive substrate, 101(101E, 101F) substrate (transparent substrate), surface of 101ET substrate, 102(102E, 102F) metal film, 103(103E, 103F) intermediate film, 104 ( system film 104E, 104F) transparent conductive film, and surface of 104ET transparent conductive film.

Claims (6)

1. A transparent conductive substrate is provided with:

a transparent substrate; and

a structure in which a metal film, an intermediate film that is an oxide film containing molybdenum (Mo), and a transparent conductive film are sequentially stacked on one surface of the transparent substrate,

the metal film formed on the transparent substrate is composed of an Al — Nd alloy containing Nd in Al,

an interface exists between the metal film and the intermediate film,

in the structure, the average reflectance of incident light in the visible light region is 10% or less,

and controlling at least one of the resistivity of the interlayer film and the thickness of the transparent conductive film so that the interlayer film changes in color tone, wherein the resistivity of the interlayer film is controlled based on adjustment of the amount of oxygen contained in the interlayer film.

2. The transparent conductive substrate according to claim 1, comprising:

in the structure, the reflectance with respect to incident light having a wavelength of 550nm is 5% or less.

3. The transparent conductive substrate according to claim 1 or 2, wherein the interlayer has a resistivity of 1.8 x 10⁸Hereinafter, the unit of the resistivity is μ Ω · cm.

4. The transparent conductive substrate according to claim 1 or 2, wherein the transparent conductive film has a film thickness in the range of 10 or more and 50 or less in units of nm.

5. The transparent conductive substrate according to claim 1 or 2, wherein a structure in which the metal film, the intermediate film, and the transparent conductive film are laminated in this order on the one surface of the transparent base has a desired pattern by etching.

6. A transparent laminated structure comprising:

a metal film made of an Al-Nd alloy containing Nd in Al;

an intermediate film provided on the metal film and serving as an oxide film containing molybdenum (Mo); and

a transparent conductive film provided on the intermediate film,

an interface exists between the metal film and the intermediate film,

in the transparent laminated structure, the average reflectance with respect to incident light in the visible light region is 10% or less,

and controlling at least one of the resistivity of the interlayer film and the thickness of the transparent conductive film so that the interlayer film changes in color tone, wherein the resistivity of the interlayer film is controlled based on adjustment of the amount of oxygen contained in the interlayer film.

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