JP3063618B2 - Electrode substrate for display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type electrode (transparent electrode) used for an output display device such as a liquid crystal display device or a plasma display device, an input / output display device for directly inputting from a display screen, a solar cell or the like.
In particular, the present invention relates to an electrode substrate which is thin and has high conductivity and high light transmittance and excellent storage stability.

[0002]

2. Description of the Related Art An electrode plate in which a transparent conductive film in the form of an electrode that transmits visible light is provided on a substrate such as a glass or plastic film is used as a display electrode of various display devices (display screens) such as a liquid crystal display device. Also, it is widely used for input / output electrodes that can be directly input from the display screen of this display device.

For example, as shown in FIG. 12, a transparent electrode plate of a display device using liquid crystal has a glass substrate 3
0, a color filter layer 31 provided at a pixel portion on the glass substrate 30 and coloring transmitted light into red, green, and blue for each pixel, and a color filter layer 31 between the pixels on the glass substrate 30 ( (Between pixels), a light-shielding film 32 for preventing light transmission from this part, a transparent protective layer 33 provided on the entire surface of the color filter layer 31, and a sputtering layer formed on the protective layer 33. The main part is composed of a patterned or solid transparent electrode 34 which is formed and etched into a predetermined electrode pattern, and an alignment film 35 formed on the transparent electrode 34.

[0004] Focusing on the high conductivity, the transparent electrode 34 is made of Idium obtained by adding tin oxide to indium oxide.
A TO thin film is widely used, and its specific resistance is about 2.4 × 10 ⁻⁴ Ω · cm. In the case of a film thickness of 240 nm which is usually applied as a transparent electrode, its area resistance value is about 10 Ω (or 10Ω / □, □; square). In addition, a tin oxide thin film, a thin film formed by adding antimony oxide to tin oxide (a Nesa film), and a thin film formed by adding aluminum oxide to zinc oxide are known. , These are all the above ITO
It is not widely used because it has poorer conductivity than thin films and has insufficient chemical resistance or water resistance against acids and alkalis.

On the other hand, in 1982, the 7th
In the ICVM, a transparent conductive film having a three-layer structure has been proposed in which an ITO thin film or an indium oxide thin film (IO thin film) is laminated on the front and back surfaces of a silver thin film as a heat ray reflective film. The transparent conductive film having the three-layer structure has a low sheet resistance value of about 5Ω, and is expected to be applied to the transparent electrode by utilizing its high conductivity.

[0006]

In the above-mentioned display devices and input / output devices, it has recently been required to increase the pixel density and display a fine screen. For example, it is required that the terminal portions of the transparent electrode be formed at a pitch of about 100 μm. Further, in a system (COG) in which a liquid crystal driving IC is directly connected to a substrate in a liquid crystal display device, wiring routing is difficult.
There is a part of a thin line having a width of 20 to 50 μm, and a high degree of suitability for etching and a high conductivity (low resistance) are required.

On the other hand, on the other hand, a large display screen is also required. For such a large screen, a transparent electrode having a dense pattern as described above is formed, and a sufficient driving voltage can be applied to the liquid crystal. In order to achieve this, it is necessary to apply a transparent electrode having a high conductivity of a sheet resistance of 5Ω or less as the transparent electrode. In addition, in a simple matrix driving type liquid crystal display device using an STN liquid crystal or the like, when a multi-gradation display of 16 gradations or more is performed, a lower sheet resistance value of 3Ω or less is required. I have.

However, the transparent electrode having the three-layer structure proposed in the 7th ICVM also has a maximum resistance of 5Ω.
However, there is a problem that sufficient conductivity cannot be ensured, and for example, by increasing the thickness of the silver thin film to about 16 to 18 nm, the area resistance becomes about 3Ω. Although it is possible to lower
The visible light transmittance (especially the visible light transmittance on the long wavelength side of about 610 nm) is reduced to about 75%, and the function as a transparent electrode is impaired.

Further, in the transparent electrode having the three-layer structure, the silver thin film easily reacts with moisture in the air that has entered from the surface of the laminated sea or the like, and generates a reaction product on the surface to cause spot-like defects. For example, when applied to a transparent electrode of a liquid crystal display device, there is a problem that a display defect or the like is easily generated on the surface.

In recent years, a polarizing plate is not used, or a single polarizing plate (usually TN type, STN type, ECB type, OCB type) is used.
Attention has been focused on a reflection type liquid crystal display device using only a B-type liquid crystal display device using two polarizing plates).

In addition, the development of a reflection type liquid crystal display device in which a reflection type electrode having a function of a light reflection plate and a display electrode in the liquid crystal cell to reduce the cost is arranged has been promoted. I have.

The present inventors have proposed to use a silver-based thin film having a higher light reflectance than an aluminum thin film over almost the entire visible region as a reflective electrode. This silver-based thin film has a problem that sulfides are formed on the surface of the silver-based thin film by being combined with a sulfur compound in the air, and the reflectivity is easily lowered. The method of laminating oxide thin films is extremely effective.

However, when a transparent oxide thin film is laminated on a silver-based thin film without considering optical conditions, the reflected light is colored yellow or pink, greatly deteriorating the display quality of the reflective liquid crystal display device. There was a problem. Further, the reflective electrode also has a drawback that, similarly to the above-mentioned transparent electrode having a three-layer structure, it has low moisture resistance, and stains are generated by moisture even when left alone.

The present invention has been made in view of such a problem, and it is an object of the present invention to provide a thin film having high conductivity and high visible light transmittance or reflectance, and without deterioration with time. An object of the present invention is to provide a transmission-type or reflection-type display device electrode substrate having excellent storage stability.

[0015]

According to the present invention, as a means for solving the above-mentioned problems, two techniques are used in combination, and one of them is to add a small amount of gold and copper to silver of a silver-based thin film. The addition is to suppress the properties of silver, and the other is to make the thin film of the transparent oxide amorphous, and to diffuse the grain boundaries of silver (silver tends to cause grain boundary diffusion between oxide crystals). Is to eliminate.

That is, according to the first aspect of the present invention, there is provided an electrode substrate in which a conductive adhesive layer, a silver-based conductive thin film layer, and an oxide-based transparent conductive thin film layer are laminated on a substrate in this order. The thin film layer is 0.1 to 2.5 at% gold and 0.3 to
An electrode substrate for a display device, comprising: a silver alloy to which 3.0 at% of copper is added; and an oxide-based transparent conductive thin film layer formed of an amorphous substance.

According to a second aspect of the present invention, in the electrode substrate for a display device according to the above invention, the thickness of the silver-based conductive thin film layer is in the range of 50 to 200 nm, and the thickness of the oxide-based transparent conductive thin film layer is It is a display device electrode substrate having a layer thickness in the range of 40 to 100 nm.

According to a third aspect of the present invention, in the electrode substrate for a display device according to the first aspect of the present invention, the silver-based conductive thin film layer has a thickness in a range of 5 to 25 nm, and the conductive adhesive layer is It is an electrode substrate for a display device containing the same type of oxide as the material-based transparent conductive thin film layer.

According to a fourth aspect of the present invention, in the electrode substrate for a display device of the present invention, the whole or a part of the conductive adhesive layer and the oxide-based transparent conductive thin film layer has a refractive index of 2.
1 is an electrode substrate for a display device containing an oxide larger than 1.

According to a fifth aspect of the present invention, in the electrode substrate for a display device of the above invention, the conductive adhesive layer and the oxide-based transparent conductive thin film layer are made of one or both of cerium oxide and titanium oxide. It is an electrode substrate for a display device containing a selected oxide.

According to a sixth aspect of the present invention, in the electrode substrate for a display device according to the invention, the conductive adhesive layer and the oxide-based transparent conductive thin film layer contain indium oxide.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION
This will be described in detail below according to the embodiment.

According to a first aspect of the present invention, there is provided an electrode substrate in which a conductive adhesive layer, a silver-based conductive thin film layer, and an oxide-based transparent conductive thin film layer are laminated on a substrate in this order. The layer is 0.1 to 2.5 at% (hereinafter atomic
weight%, atomic weight percent is referred to as at%)
This is a display device electrode substrate formed of a silver alloy to which gold and 0.3 to 3.0 at% of copper are added, and an oxide-based transparent conductive thin film layer formed of an amorphous substance.

The amount of gold to be added to the silver-based conductive thin-film layer on the substrate is such that the conductive adhesive layer, the silver-based conductive thin-film layer, and the oxide-based transparent conductive thin-film layer, each of which has a three-layer structure, have moisture resistance. Regarding the improvement of the properties, the effect is effective from the addition of a small amount of 0.1 at%, and the moisture resistance tends to improve as the addition amount increases.

However, if the amount of gold added is large, the resistance value of the conductive film increases, and if it is 2.5 at% or more, residues are likely to remain during the etching of the conductive film. is necessary.

The addition of copper to the silver-based conductive thin film layer contributes to the improvement of the moisture resistance as described above, and the addition of silver (Ag) alone or two elements of Ag-Au (gold) during sputtering film formation. The thickness of the film and the transmittance after the film are easily changed by the influence of oxygen in the gas atmosphere.
Addition eliminates dents and is therefore less susceptible to the effects of the atmosphere, and is particularly effective in increasing the margin (allowable amount of film formation conditions, etc.) when forming the silver-based conductive thin film layer.

More specifically, when a large amount of oxygen is present in a gas introduced into the silver-based conductive thin film layer or in the background, light absorption occurs at a wavelength of about 470 nm, and the light transmittance (reflection type) as a transparent electrode is generated. The electrode has a lower reflectance).

FIG. 5 shows that the silver-based conductive thin film layer has a thickness of 0.1 to 2.5.
a transparent silver-based conductive thin film layer formed of a silver alloy to which at% of gold and 0 at% to 3.0 at% of copper are added, and a three-layer formed of an oxide-based transparent conductive thin film layer made of an amorphous substance 5 is a graph showing the spectral transmittance of a transparent electrode substrate for a display device having a structure (total thickness of a conductive film having a three-layer structure; about 85 nm). In the case of adding 3 at%, the graph shows copper 1.0a.
In the case of adding t%, the graph shows the case of adding 3.0 at% of copper. As shown in FIG. 5, the amount of copper added to the silver-based conductive thin film layer gradually increases from about 0.3%. This has the effect of reducing dents on the short wavelength side and increasing the drop in transmittance on the short wavelength side.

Since copper takes a eutectic (not completely solid solution) form with silver, an increase in the amount of added copper adversely affects light transmittance or reflectance.
When the amount of addition increases, the resistance value of the conductive film tends to increase.

For example, if the thickness of the silver-based conductive thin film layer is 10
When the thickness is set to about 11 nm and the addition amount of copper is set to 3 at% or more, the sheet resistance value exceeds 5Ω.

In order to make the above-mentioned oxide-based transparent conductive thin film layer amorphous, a certain kind of metal oxide is mixed with a considerable amount of a different metal (depending on the compatibility of the oxide, but generally 20% or more). The substrate temperature is set low (for example, 20
It is convenient to make the film amorphous (eg, at or below room temperature or at room temperature).

The metal oxide may be selected from materials having excellent acid resistance, alkali resistance and heat resistance.

Next, assuming that the reflective electrode is used, a conductive adhesive layer (for example, a film having a thickness of 10 nm, a refractive index of 2.3, but a refractive index depending on the light wavelength) is formed on a glass substrate. Ignored chromatic dispersion such as changes in absorption coefficient)
A simulation was performed on a reflective display electrode substrate in which a silver-based conductive thin film layer having a thickness of 50 nm to 200 nm and an oxide-based transparent conductive thin film layer (eg, a film thickness of 40 nm) were sequentially stacked.

FIG. 11 shows a simulation result of the reflectance of the conductive thin film layer of the reflective display electrode substrate. The graph shows the thickness of the silver-based conductive thin film of 50 nm, the graph shows the thickness of the silver-based conductive thin film of 75 nm, the graph shows the thickness of the silver-based conductive thin film of 100 nm, and the graph shows the thickness of the silver-based conductive thin film of 2.
The case of 00 nm is shown. The refractive index of the measurement medium (medium interposed in the path of the measurement light) used was 1.5.

Next, the invention according to claim 2 of the present invention will be described in detail below according to embodiments.

According to a second aspect of the present invention, in the electrode substrate for a display device according to the first aspect of the present invention, the thickness of the silver-based conductive thin film layer is in the range of 50 to 200 nm, and the oxide-based transparent conductive layer is formed. This is a display device electrode substrate in which the thickness of the thin film layer is in the range of 40 to 100 nm.

That is, the invention according to claim 2 is based on the premise that the reflective display electrode substrate is used, wherein the thickness of the silver-based conductive thin film layer as the reflective layer is in the range of 50 nm to 200 nm, and the oxide-based transparent electrode layer is transparent. The thickness of the conductive thin film layer is 40 nm to 100 n
m.

FIG. 11 shows the effect of the thickness of the silver-based conductive thin film layer on the reflectance. When the thickness of the silver-based conductive thin film layer exceeds 50 nm, the reflective electrode having a reflectance of about 80% is used. It is shown that at 200 nm, the reflectance is saturated and the light transmittance becomes almost 0%.

FIG. 8 and FIG. 9 show the simulation results in consideration of the wavelength dispersion of the relationship between the thickness of each silver-based conductive thin film layer and the reflectance in the reflective electrode.
Table 1 shows the optical constants (refractive index, light extinction coefficient) of the silver-based conductive thin film layer (AgAuCu) and the oxide-based conductive thin film layer (ICTTO).

[0040]

[Table 1]

The oxide-based transparent conductive thin film layer has a thickness of 30
It is shown that the reflectance at 435 nm (the main wavelength of blue) is as low as about 70% below nm and above 110 nm.

The thickness of the oxide-based transparent conductive thin film layer is
In the range of 40 nm to 100 nm, it has been shown to have a good reflectance.

Next, the invention according to claim 3 of the present invention will be described in detail below according to embodiments.

According to a third aspect of the present invention, in the electrode substrate for a display device according to the first aspect of the present invention, the silver-based conductive thin film layer has a thickness in a range of 5 to 25 nm, and An electrode substrate for a display device, wherein the layer contains the same kind of oxide as the oxide-based transparent conductive thin film layer.

FIG. 10 shows that a conductive adhesive layer (for example, a film thickness of 35 nm and a refractive index of 2.2) made of an oxide-based transparent conductive thin film is formed on a glass substrate on the assumption that the transmission electrode is used.
A simulation of a spectral transmittance of a transmission type display electrode substrate in which a silver-based conductive thin film layer of 15 nm to 25 nm and an oxide-based transparent conductive thin film layer (for example, a film thickness of 40 nm) are sequentially stacked is shown. The graph shows the thickness of the silver-based conductive thin film layer of 15n.
m, the graph is the thickness of the silver-based conductive thin film layer 17.5 nm, the graph is the thickness of the silver-based conductive thin film layer 20.0 nm, the graph is the thickness of the silver-based conductive thin film layer 22.5 nm, and the graph is the silver-based conductive thin film layer And a refractive index of 1 was used as the measurement medium as air.

Even in the region where the thickness of the silver-based conductive thin film layer is relatively thick, 25 nm, the peak transmittance is 80%, which is relatively good.
Is obtained. The thickness of the silver-based conductive thin film layer is slightly over 20 nm, and the three-layer conductive film has a sheet resistance of about 2Ω.

If the thickness of the silver-based conductive thin film layer is less than 5 nm, it becomes island-like (land-like) and does not become a uniform film, so that it is possible to calculate appropriate optical characteristics and resistance values in calculation. It becomes difficult, and in a region of an extremely thin film having a thickness of 5 nm or less, a good three-layer conductive film is not obtained.

In addition, the conductive film having a three-layer structure on the premise of a transmission type display electrode substrate is formed by depositing an oxide-based transparent conductive thin film layer on both the front and back sides of the silver-based conductive thin film layer. (For example, conditions at the time of film formation, oxygen partial pressure, and the like) are more similar to each other, which has a better influence on the transmittance and the resistance value.

Further, if the film-forming material of the oxide-based transparent conductive thin film layer on each of the front and back surfaces of the silver-based conductive thin film layer is the same, material management such as a sputtering film-forming target is easy.

In recent years, the technical progress of simple matrix type liquid crystal display devices such as STN and ECB has been remarkable, and there has been a movement to use a color STN type as a monitor instead of a CRT. Connection to an external power supply is possible, and this makes it possible to use a high-brightness backlight.

From this point of view, in a simple matrix type liquid crystal display device for monitor use, the transmittance of the transparent electrode used for this purpose may be sacrificed to some extent, giving priority to a low resistance value. In such a simple matrix system, the effect of the resistance value of the transparent electrode is extremely large in improving the image quality, and when the area resistance value of the transparent electrode is close to 2Ω, the image quality called shadowing is hardly reduced. As a display, it can compete with the TFT method at a practical level.

Next, the invention according to claim 4 of the present invention will be described in detail below according to embodiments.

According to a fourth aspect of the present invention, in the electrode substrate for a display device according to the third aspect of the present invention, the whole or a part of the conductive adhesive layer and the oxide-based transparent conductive thin film layer is
It is a display device electrode substrate containing an oxide having a refractive index greater than 2.1.

The present inventors have further studied and found that, as described above, the structure of a three-layered conductive film using an oxide having a refractive index greater than 2.1 for the oxide-based transparent conductive thin film layer However, it has been found that even better results can be obtained.

Then, an oxide having a high refractive index (the oxide is not limited as long as it is transparent in the visible light region, but an oxide is practical in terms of production cost, etc.) is replaced with an adhesive layer or an oxide. It has been found that the insertion into the whole or a part of the system transparent conductive thin film layer is effective in improving the light transmittance.

The light transmittance can be increased by using a high refractive index material by using a liquid crystal material having a refractive index higher than that of air (normal liquid crystal has a refractive index of about 1.5 to 1.6) or a color. 3 intended for a liquid crystal display device in contact with a filter (the refractive index of the material of the color filter is slightly more than 1.5)
This is remarkable in the case of a conductive film having a layer structure.

A simulation result when one side of a three-layered transmission type display electrode formed on a substrate such as glass is air is shown by the line B in FIG. , The reflectance R drops to a position close to 1%, and a good result as a transmissive display electrode substrate (transparent electrode) can be obtained.

Here, the thickness of the adhesive layer of the transparent oxide thin film on the substrate side is 40 nm, the thickness of the transparent silver-based conductive thin film layer (Ag thin film) is 14 nm, and the oxide-based transparent conductive thin film layer on the side in contact with air. The thickness of the (transparent oxide thin film) was 44 nm. And the refractive index of these transparent oxide thin films was calculated as 2.0 which is almost the same as that of ITO.

However, when a polyimide alignment film is laminated on the transparent electrode having a three-layer structure to a thickness of 40 nm and the refractive index of the liquid crystal in contact therewith is calculated as 1.5, the transmittance T as shown by line A in FIG. Indicates that the peak falls to 90% or less and the reflectance R
Rises to about 10% around the light wavelength of 550 nm,
The performance as a transmission type display electrode substrate (transparent electrode) will be reduced.

Based on this, the present inventors have calculated on the assumption that a liquid crystal is in contact with a polyimide film as an alignment film of a liquid crystal on a transmission type display electrode substrate having a three-layer structure. The optimization was performed by changing the refractive index of each of the transparent oxide thin films sandwiched between them (by changing the refractive index and simultaneously adjusting the film thickness).

FIG. 6 shows the result. From this figure, it can be seen that the higher the refractive index of the transparent oxide thin film particularly exceeds 2.1, the higher the transmittance and the lower the reflectance.

Next, the invention according to claim 5 of the present invention will be described in detail below according to embodiments.

According to a fifth aspect of the present invention, in the electrode substrate for a display device according to the third or fourth aspect, the conductive adhesive layer and the oxide-based transparent conductive thin film layer are made of cerium oxide and titanium oxide. A display device electrode substrate containing an oxide selected from one or both of the above.

Assuming that a transmission type display electrode substrate (transparent electrode) is used, the transmittance is improved by using a high refractive index material as the material used for the transparent oxide thin film used in the present invention. .

Typical oxides of this high refractive index material are cerium oxide and titanium oxide,
The light transmittance of a three-layer conductive film as a transparent electrode is reduced by forming a transparent conductive adhesive layer and an oxide-based transparent conductive thin film layer by mixing with a heterogeneous oxide at a ratio of about 80%. It is to improve.

Next, the invention according to claim 6 of the present invention will be described in detail below according to embodiments.

According to a sixth aspect of the present invention, in the electrode substrate for a display device according to the third or fourth or fifth aspect, the conductive adhesive layer and the oxide-based transparent conductive thin film layer are formed of indium oxide. Is an electrode substrate for a display device.

In the electrode substrate for a display device of the present invention,
In order to drive the display element, it is necessary to establish electrical conduction from the surface of the transparent oxide thin film.

In order to make the transparent oxide thin film amorphous in a form that is relatively thermally stable (for example, crystallization does not proceed even by annealing at about 250 ° C.), as described above, It is necessary to form a mixed oxide thin film to which different oxides are added in the range of about 20 to 80%.

Few oxides can be electrically connected in such an amorphous mixed oxide state, and it is advantageous to use indium oxide as the material of the transparent oxide thin film within the range studied by the present inventors. I found something.

More specifically, indium oxide and cerium oxide (or titanium oxide) were added at about 20 to 8
A film may be formed by a film formation method such as sputtering using an oxide target mixed in a range of 0%. In addition,
The mixing ratio does not need to be in the above range as long as the transparent oxide thin film is amorphous.

The display device electrode substrate of the present invention includes both a transmission type and a reflection type display device electrode substrate. For example, in the case of a reflection type display device electrode substrate, The substrate used may be a transparent substrate such as glass or plastic, or a transparent or opaque substrate colored white, black or other colors. Various materials can be used for the substrate, such as glass, plastic films, plastic sheets, ceramics, metal plates, or substrates on which semiconductor elements such as amorphous silicon, polysilicon, and MIM are formed. In addition, a color filter layer (for example, red, green, and blue colored layers) may be formed in a pattern on the substrate to be used in advance.

Since the three-layered conductive film of the present invention has a low resistance value, it can be used for signal lines and bus lines of elements such as TFTs and MIMs, and can also be used as these pixel electrodes. is there.

[0074]

EXAMPLES Specific examples of the present invention will be described below.

<Embodiment 1> As shown in FIG. 1, a transmission type display device electrode substrate 15 according to this embodiment has a thickness of 0.1 mm.
35 n in thickness sequentially laminated on a 7 mm glass substrate 10
m, a transparent oxide thin film 11 (oxide-based transparent conductive thin-film layer), a transparent silver-based conductive thin film 12 (silver-based conductive thin-film layer) having a thickness of 14 nm, and a transparent thin film having a thickness of 38 nm. The oxide thin film 13 (oxide-based transparent conductive thin film layer) forms a main part thereof. The transparent oxide thin film 1
Each of 1 and 13 was a mixed oxide in which cerium oxide (32 at% in terms of a metal element excluding oxygen) was added to a thin film of indium oxide. The silver-based thin film 12 between the transparent oxide thin films 11 and 13 is formed by adding 1.0 at% of gold to silver.
And 1.5 at% of copper.

Then, the transparent conductive film 14 having the three-layer structure is formed.
Was formed by the following method. First, the glass substrate 1
After the surface of No. 0 was washed with an organic alkali-based surfactant and water, it was housed in a vacuum chamber, subjected to a plasma treatment called reverse sputtering, and further washed.

Next, the transparent oxide thin film 11, the silver thin film 12, and the transparent oxide thin film 13 are successively formed by the sputtering method without removing the glass substrate 10 from the vacuum chamber and keeping the glass substrate 10 at room temperature. Laminated films were formed.

Next, a resist film in the form of an electrode is patterned on the transparent oxide thin film 13 by photolithography, and the portion exposed from the resist film is etched with a nitric acid-based etchant to form the above three-layer structure. The thin film is patterned into an electrode shape in a state where the thin films are aligned with each other, and then subjected to an annealing process at 220 ° C. for 1 hour to form the transparent electrode 14 having the electrode shape. No. 15 was produced. The sheet resistance of the transparent electrode 14 thus obtained was about 3.3Ω.

FIG. 4 shows the visible light transmittance (graph) of the transparent electrode 14 of Example 1 provided with the silver-based conductive thin film layer having a thickness of 14 nm by a solid line. The graph shows a film thickness of 1
The transmittance of the transparent electrode 14 (area resistance: about 4.6Ω) provided with a silver-based conductive thin film layer of 2 nm or less,
The transmittance of the transparent electrode 14 (thickness: about 90 nm, sheet resistance: about 2.2Ω) provided with a silver-based conductive thin film layer of 10 nm is shown.

This patterned transparent electrode 14 is
After keeping for 500 hours in an atmosphere of 95 ° C. and 95% humidity,
The surface was observed. As a result, the surface did not change appearance at all. The refractive index of the transparent electrode 14 due to this mixed oxide was measured and found to be 2.24.

When the crystallinity of the transparent electrode 14 was examined by thin film X-ray diffraction, a fine silver peak due to the silver thin film 12 was observed, but a crystal peak due to the transparent oxide thin films 11 and 13 was observed. Was not done.

The transparent electrode 14 is also thermally stable, and no crystal peak is observed in the transparent oxide thin film even when the heat treatment is performed up to 300 ° C., and almost no increase in the sheet resistance is observed. Was.

<Embodiment 2> As shown in FIG. 2, the reflective display device electrode substrate 25 according to this embodiment has a thickness of 0.1 mm.
An oxide thin film 21 (transparent to opaque oxide thin film) having a thickness of 10 nm, which is a conductive adhesive layer, and a silver-based thin film 22 having a thickness of 150 nm, which are sequentially laminated on a 5 mm glass substrate 20.
(Silver-based conductive thin film layer) and the transparent oxide thin film 23 (oxide-based transparent conductive thin film layer) having a thickness of 75 nm constitute main parts thereof.

The transparent oxide thin films 21 and 23 are made of indium oxide, cerium oxide, tin oxide and titanium oxide in an atomic percentage of only metal atoms not including oxygen atoms of 66 in% indium and 32 at cerium. 5
at%, tin 1.0 at%, and titanium 0.5 at%. The sheet resistance of these three-layered reflective conductive films 24 was about 0.2Ω.

FIG. 3 shows the spectral characteristics of this reflective display device electrode substrate 25.
At m to 700 nm, a high reflectance of about 90% or more was obtained.

Then, the reflective conductive film 24 having the above three-layer structure is formed.
Was formed by the following method. First, the glass substrate 2
After the surface of No. 0 was washed with an organic alkali-based surfactant and water, it was housed in a vacuum chamber, subjected to a plasma treatment called reverse sputtering, and further washed.

Next, the transparent oxide thin film 21, the silver thin film 22, and the transparent oxide thin film 23 are sequentially formed by a sputtering method without removing the glass substrate 20 from the vacuum chamber and keeping the glass substrate 20 at room temperature. Laminated films were formed.

Next, a resist film in the form of an electrode is patterned on the transparent oxide thin film 23 by photolithography, and the portion exposed from the resist film is etched with a nitric acid-based etchant to form the above-mentioned three-layer structure. The thin film is patterned into an electrode shape in a state where the thin films are aligned with each other, followed by annealing at 220 ° C. for 1 hour to form the reflective conductive film 24 in the electrode shape. The substrate 25 was manufactured. The sheet resistance of the reflective conductive film 24 thus obtained was about 0.2Ω.

When the crystallinity of the reflective conductive film 24 was examined by thin film X-ray diffraction, a silver crystal peak due to the silver thin film 22 was observed, but a crystal peak due to the transparent oxide thin films 21 and 23 was not observed. .

The reflective conductive film 24 is thermally stable,
No crystal peak due to the transparent oxide thin films 21 and 23 was observed even when the heat treatment was performed to 0 ° C. The surface was observed for 500 hours in an atmosphere at a temperature of 60 ° C. and a humidity of 95%, and the surface was observed.

[0091]

According to the present invention, the electrode substrate for a display device can be obtained by using a silver alloy obtained by adding a small amount of gold and copper to silver for a silver-based thin film and, at the same time, making the transparent oxide thin film amorphous. It is possible to impart moisture resistance to an electrode substrate for a display device, and has an effect of increasing reliability. In addition, by using a transparent oxide thin film having a high refractive index of 2.1 or more, a transmission type having a high transmittance can be obtained. This has the effect of obtaining a reflective electrode substrate for display devices having a high reflectivity over the entire wavelength range of visible light, and has a thin film, low resistance, and good conductivity. In addition to the above, the present invention has a practical effect as a transmission or reflection type electrode substrate for a display device which has a high visible light transmittance or a reflectance and is excellent in storage stability without deterioration over time.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a transmission type electrode substrate for a display device of the present invention.

FIG. 2 is a side sectional view of an electrode substrate for a reflective display device of the present invention.

FIG. 3 is a graph showing the spectral reflectance of a reflective display device electrode substrate of the present invention.

FIG. 4 is a graph showing the spectral transmittance of a transmission type electrode substrate for a display device of the present invention.

FIG. 5 is a graph showing the relationship between the amount of copper added to a silver-based conductive thin film and the spectral transmittance at that time in the transmission-type display device electrode substrate of the present invention.

FIG. 6 shows a spectral transmittance T obtained by simulation when a refractive index of a measurement medium is 1.0 in a transmission-type electrode substrate for a display device using a transparent oxide-based conductive thin film having a refractive index of 2;
And a graph B showing the spectral reflectance R and a graph A showing the spectral transmittance T and the spectral reflectance R by simulation when the refractive index of the measurement medium is 1.5.

FIG. 7 is a cross-sectional view of a transmission type electrode substrate for a display device according to the present invention.
The graph which shows the relationship between 2.4) and transmittance | permeability.

FIG. 8 shows the thickness (30) of the oxide-based transparent conductive thin film layer on each of the silver-based conductive thin film layers in the reflective display electrode substrate of the present invention.
and a graph showing simulation results of the spectral reflectance.

FIG. 9 shows the thickness (70) of the oxide-based transparent conductive thin film layer on each of the silver-based conductive thin film layers in the reflective display electrode substrate of the present invention.
and a graph showing simulation results of the spectral reflectance.

FIG. 10 is a graph showing the relationship between the thickness of a silver-based conductive thin film and the transmittance (reflectance) of a transmission-type display electrode substrate according to the present invention based on simulation results.

FIG. 11 is a graph showing a relationship between a film thickness of a silver-based conductive thin film of a reflective display electrode substrate of the present invention and a reflectance based on a simulation result.

FIG. 12 is a side sectional view of a transmission type display electrode substrate of a conventional liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Substrate 11 ... Transparent conductive adhesive layer 12 ... Silver-based transparent conductive thin film layer 13 ... Oxide-based transparent conductive thin film layer 14 ... Transparent conductive film 1
5: Transparent display electrode substrate 20: Substrate 21: Conductive adhesive layer 22: Silver-based conductive thin film layer 23: Oxide-based transparent conductive thin film layer 24: Reflective conductive film 2
5: reflective display electrode substrate 30: substrate 31: color filter layer 32: light-shielding film layer 33: transparent protective layer 34: transparent conductive layer 35: alignment film layer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-115351 (JP, A) JP-A-6-214252 (JP, A) JP-A-6-18927 (JP, A) JP-A 8-108 262203 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G09F 9/30 G02F 1/1343

Claims (6)

(57) [Claims] 1. An electrode substrate having a conductive adhesive layer, a silver-based conductive thin film layer, and an oxide-based transparent conductive thin film layer laminated in this order on a substrate, wherein the silver-based conductive thin film layer has a thickness of 0.1 to 2.5 at. %
An electrode substrate for a display device, comprising an oxide-based transparent conductive thin film layer formed of an amorphous material, formed of a silver alloy to which gold and 0.3 to 3.0 at% of copper are added. 2. The silver-based conductive thin film layer has a thickness of 50 to 200.
2. The electrode substrate for a display device according to claim 1, wherein the thickness of the oxide-based transparent conductive thin film layer is in the range of 40 to 100 nm. 3. The silver-based conductive thin film layer has a thickness of 5 to 25 nm.
The electrode substrate for a display device according to claim 1, wherein the conductive adhesive layer contains an oxide of the same type as the oxide-based transparent conductive thin film layer. 4. The electrode substrate for a display device according to claim 3, wherein the whole or a part of the conductive adhesive layer and the oxide-based transparent conductive thin film layer contains an oxide having a refractive index greater than 2.1. 5. The method according to claim 3, wherein the conductive adhesive layer and the oxide-based transparent conductive thin film layer contain an oxide selected from one or both of cerium oxide and titanium oxide. An electrode substrate for a display device. 6. The electrode substrate for a display device according to claim 3, wherein said conductive adhesive layer and said oxide-based transparent conductive thin film layer contain indium oxide.