JPH09281473A - Production of electrode substrate and display element using electrode substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain both of low resistance and high reliability in a terminal part by forming a transparent conductive thin film having a multilayered structure including a metal thin film on a transparent substrate, then selectively etching the transparent conductive thin film to the depth of the metal thin film layer according to a specified pattern, and processing the selectively etched transparent conductive thin film to form a specified electrode pattern. SOLUTION: First, an ITO thin film 2, a silver thin film 3 and an ITO thin film 2 are successively formed to obtain a multilayered transparent conductive thin film on a transparent substrate 1 by sputtering (a). Then a resist 4 is applied and subjected to prebaking, exposure, development and postbaking to form a specified resist pattern (b). Further, an etching liquid is used to selectively remove the ITO thin film 2 and the silver thin film 3 as the upper transparent electrode while controlling the etching time (c). Then the resist 4 is peeled (d). Further, the resist 4 is again applied to form a resist pattern (e). Then the electrode pattern is formed by etching (f).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of an electrode substrate applied to a display device used in video display equipment, office automation equipment such as personal computers and word processors, handy terminal equipment in the industrial field, and portable information communication equipment. The present invention relates to a method and a display element using an electrode substrate.

[0002]

2. Description of the Related Art Currently, liquid crystal, plasma, and EL displays have been put to practical use as flat panel displays.
Its applications are becoming widespread.

Current liquid crystal display devices are
Although screen size and number of pixels are inferior,
Excellent portability in weight and volume. For example, as a liquid crystal display device currently used in notebook computers and word processors, a device with a size of 10 to 12 inches is used.
Some of them have a pixel number of x480 dots or 600x800 dots, and although they are inferior to the pixel number of a CRT, they can provide excellent display as a display.

However, in the simple matrix, a phenomenon called crosstalk occurs due to the design of the liquid crystal panel and the drive circuit, and the degree of crosstalk varies depending on the type of pattern to be displayed. This crosstalk is
It can be confirmed as shadows in the vertical and horizontal directions of the projected image, and when a voltage is applied to turn on the pixels whose liquid crystal panel is driven by the line-sequential method, some amount of light is emitted in addition to the turned-on pixels. Voltage is applied and crosstalk with a display different from the normal one occurs. In addition, the signal waveform is distorted even in the case of an AC signal, and a voltage corresponding to the distortion is applied to cause crosstalk. In addition, the crosstalk is greatly influenced by the capacitance component of the liquid crystal panel including the liquid crystal material and the cell gap and the wiring resistance value of the transparent electrode.

FIG. 10 is a constitutional view showing an example of the constitution of such a conventional simple matrix type color STN liquid crystal display element, in which a transparent electrode 2 is provided on the lower surface of a transparent substrate 7 and further covers the transparent electrode 2. Thus, the alignment film 8 made of polyimide or the like is sequentially formed. A color filter layer 5 and a smoothing layer 6 made of an organic material for smoothness are provided on the transparent substrate 1 facing each other.
And an alignment film 8 are sequentially formed on the upper surface. The electrode substrate configured in this way has the spacer 9 interposed therebetween,
Seal resin printed around at least one substrate 11
Are bonded so as to keep the gap between the electrode substrates constant, and the liquid crystal 10 is sealed in the gap to form a color liquid crystal display element.

In general, a sputtering film forming technique using an In—Sn oxide (ITO) target is most often used to form the transparent electrode 2, but a method for forming an ITO film (transparent electrode) is used. There are various types, and in the related art, the ITO film can be formed by the printing method and a certain result has been achieved. However, the problem with the printing method is that it is not a thin film but a thick film, or that it cannot form a fine line pattern. Further, there is a limitation in using a glass substrate because the firing temperature is 400 to 600 ° C.

On the other hand, the ITO film formed by the sputtering method or EB (electron beam) has a low temperature of 200 to 400 ° C. and does not damage the glass. The electric resistance value is about 2000 Å, which is about 10Ω / □, and the film quality is densely packed, so the electric conductivity can be secured even if the crystal grains themselves are small. Further, although it depends on an apparatus and a target to form a film having uniform electric characteristics on a large-area glass substrate, it is excellent in mass productivity. Photolithography can be used to form the wiring pattern of the transparent electrodes, and it is possible to achieve a drawing width of 20 μm to several μm. The narrower the drawing width is, the higher the fineness and the panel transmittance can be increased.

10-inch color S using such a transparent electrode
To design a product that satisfies users with a TN liquid crystal display device (640 x 480 dots), set the area resistance value to 7
~ 10Ω / □ is required. If the area resistance value is larger than that, crosstalk increases in the liquid crystal panel, and the threshold voltage value in the liquid crystal panel is different between the left and right regions, which causes a phenomenon called luminance inclination. This crosstalk appears as shadows of vertical and horizontal lines due to display patterns such as gradation and character patterns. from now on,
The STN liquid crystal display element is considered to have a screen size of 12 to 17 inches, and the display capacity is SVGA (Super Video Grafi).
c Array) to XGA (Xtend Grafic Array), SXGA (S
Upper Xtend Grafic Array) is also attracting attention as a CRT alternative monitor. There is concern that the amount of crosstalk and the brightness gradient will increase even with this tendency. Therefore, it is necessary to develop a drive circuit that considers the voltage application waveform that is corrected according to the display pattern, or further reduce the sheet resistance of the transparent electrode. Also, it is required to reduce C (capacitance component) and R (resistance component) of the liquid crystal panel.

In addition, since the plasma display also generates heat due to the current flowing through the display electrode, it is required to reduce the resistance of the transparent electrode.

As a method for lowering the resistance of the transparent electrode, a film forming method is further devised, and a structure of a multilayer film electrode sandwiching a metal thin film is proposed.

Conventionally, as a multilayer electrode for a liquid crystal display element, there is a technique disclosed in Japanese Patent Laid-Open No. 2-37326. Figure 1 shows a cross-sectional view and plan view of the color liquid crystal substrate.
1 and FIG. 12, in which the first metal oxide film (transparent electrode) 2 / metal thin film 3 / third on the color filter 5 provided on the upper surface of the transparent substrate 1 via the smoothing layer 6. A transparent electrode having a three-layer structure of the second metal oxide film 2 is formed,
The display electrode and the mounting terminal portion are formed of a multilayer film electrode.

[0012]

However, when such a multilayer film electrode is used, the electrode resistance can be reduced, but the reliability of the metal thin film is extremely poor. It is desirable to use silver as the metal thin film in consideration of transparency and electrical conductivity, but the adhesion with the transparent metal oxide film typified by ITO is weak, and scratches may occur due to mechanical friction, or in a high humidity atmosphere. If it is left inside for a long time, moisture penetrates from the interface of the multilayer film electrode formed by etching, corroding silver and causing problems such as peeling. That is, it is not possible to meet the reliability required for the terminal portion where the tab for driving the display device is mounted, and it is difficult to put it into practical use.

The object of the present invention is to solve the above-mentioned problems. Even when a multilayer transparent electrode sandwiching the metal thin film is used, its low resistance performance and high reliability of the terminal portion An object of the present invention is to provide a manufacturing method of an electrode substrate and a display element using the electrode substrate, which are capable of satisfying both of the requirements.

[0014]

In order to achieve the above object, a method of manufacturing an electrode substrate according to the present invention comprises a step of forming a transparent conductive thin film having a multilayer structure in which a metal thin film is sandwiched on a transparent substrate, and the multilayer structure. The step of selectively etching the transparent conductive thin film in a predetermined pattern up to the metal thin film layer, and the step of processing the selectively etched transparent conductive thin film into a predetermined electrode pattern.

Also, a step of forming a transparent conductive thin film on the transparent substrate, a step of forming a metal thin film in a predetermined pattern on the transparent substrate, and a step of forming a transparent metal oxide film on the transparent substrate. And a step of processing the transparent conductive thin film having a multilayer structure on the transparent substrate into a predetermined electrode pattern.

Further, a step of forming a multi-layered transparent conductive thin film sandwiching a metal thin film on a transparent substrate, and a step of processing the multi-layered transparent conductive thin film into a predetermined electrode pattern,
There is a step of selectively etching the electrode pattern to a predetermined pattern and down to the metal thin film layer.

Further, a step of forming a predetermined resist pattern on the transparent substrate, a step of forming a transparent conductive thin film on the transparent substrate, and a step of forming a metal thin film and a metal oxide film on the transparent substrate in a predetermined pattern. And a step of forming an electrode pattern by removing the resist.

Further, the transparent substrate can be applied to a substrate on which a color filter layer is formed.

Further, a display device using the electrode substrate of the present invention is a display device using the electrode substrate manufactured by any one of the above-described electrode substrate manufacturing methods, and has a multi-layered transparent structure including a metal thin film. The electrode is configured so as not to extend to the mounting terminal portion.

Further, the display element can be applied to a display element having a liquid crystal display structure.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS. Note that the figure
Members corresponding to the members described in FIGS. 10 to 12 are designated by the same reference numerals, and detailed description thereof will be omitted.

(Embodiment 1) FIG. 1 is a schematic view of a method of manufacturing an electrode substrate according to the present invention, and FIG. 2 is a process chart of the method of manufacturing the electrode substrate.

First, a multilayer transparent conductive thin film is formed on the transparent substrate 1 in the order of the ITO thin film 2, the silver thin film 3, and the ITO thin film 2 by sputtering. Film thickness from substrate side is 500Å / 150Å /
It is 500Å (Fig. 1 (a), Fig. 2 (a)). Next, a resist 4 is applied, and a predetermined resist pattern is formed by the steps of pre-baking-exposure-developing-post-baking (FIG. 2 (b)). Further, using an etching solution, ITO as an upper transparent electrode
The thin film 2 and the silver thin film 3 are selectively removed by controlling the etching time (FIG. 2 (c)). Next, the resist 4 is peeled off
(Fig. 1 (b), Fig. 2 (d)). Further, the resist 4 is applied again to form a resist pattern in the same manner as in the exposure step (see FIG. 2).
(e)). Next, by the same etching process as described above (see FIG.
(f)), an electrode pattern is formed (FIG. 1 (c), FIG. 2 (g)). Finally, it was aged at 200 ° C. for 1 hour in vacuum to form a display electrode.

The transparent electrode thus formed exhibits low resistance characteristics equivalent to 3Ω / □ and has a transmittance of 80 at 550 nm.
% Or more, showing excellent characteristics.

(Embodiment 2) FIG. 3 is a schematic view of a method of manufacturing an electrode substrate according to the present invention, and FIG. 4 is a process chart of the method of manufacturing the electrode substrate.

First, the ITO thin film 2 is formed on the transparent substrate 1 by sputtering. The film thickness is 500Å (Fig. 3
(a), FIG. 4 (a)). Next, the silver thin film 3 is formed by sputtering through a mask so as to have a film thickness of 150Å and a predetermined pattern (FIGS. 3 (b) and 4 (b)). Further, an ITO thin film 2 of 500 Å is formed thereon by spattering to form a multilayer transparent conductive thin film (FIG. 4 (c)). Then, the resist 4 is applied, and a predetermined resist pattern is formed by the steps of pre-baking-exposure-developing-post-baking (FIG. 4 (d)). Next, the multilayer transparent conductive thin film is collectively etched using an etching solution (FIG. 4E) to form an electrode pattern (FIGS. 3D and 4F). Finally in vacuum at 200 ℃ ・ 1
Aging was performed for time to form a display electrode.

The transparent electrode thus formed exhibits a low resistance characteristic equivalent to 3Ω / □ and has a transmittance of 80 at 550 nm.
% Or more, showing excellent characteristics.

(Embodiment 3) FIG. 5 is a schematic view of a method of manufacturing an electrode substrate according to the present invention, and FIG. 6 is a process drawing of the method of manufacturing the electrode substrate.

First, a multilayer transparent conductive thin film of ITO thin film 2, silver thin film 3 and ITO thin film 2 is formed on the transparent substrate 1 by sputtering. The film thickness is 500Å / 150Å / 50 from the substrate side
It is 0Å (Fig. 5 (a), Fig. 6 (a)). Next, a resist 4 is applied, and a predetermined resist pattern is formed by the steps of pre-baking-exposure-developing-post-baking (FIG. 6 (b)). Next, the multilayer transparent conductive thin film is collectively etched using an etching solution (FIG. 6 (c)) to form an electrode pattern (FIG. 5).
(b), FIG. 6 (d)). Next, the resist 4 is applied again to form a predetermined pattern in the same manner as the above-mentioned exposure process (see FIG.
(e)). Then, the ITO thin film 2 and the silver thin film 3 are etched.
Is selectively removed by controlling the etching time to form an electrode pattern (FIGS. 5 (c) and 6 (f)). Finally, it was aged at 200 ° C. for 1 hour in vacuum to form a display electrode.

The transparent electrode thus formed exhibits low resistance characteristics equivalent to 3Ω / □ and has a transmittance at 550 nm of 80.
% Or more, showing excellent characteristics.

(Embodiment 4) FIG. 7 is a schematic view of a method of manufacturing an electrode substrate according to the present invention, and FIG. 8 is a process chart of the method of manufacturing the electrode substrate.

First, a resist pattern for forming an electrode pattern is formed on the transparent substrate 1 (FIGS. 7A and 8).
(a)). Next, a 500 Å ITO thin film 2 is formed by sputtering, and further a silver thin film 3 is formed by sputtering through a mask so that the film thickness is 150 Å and has a predetermined pattern (FIGS. 7 (b) and 8). (b)). Further, a 500 l ITO thin film 2 is formed thereon by sputtering to form a multilayer transparent conductive thin film (FIGS. 7 (c) and 8 (c)).
Then, the resist 4 is peeled off to form a pattern of the multilayer transparent conductive thin film (FIGS. 7D and 8D). Finally, it was aged at 200 ° C. for 1 hour in vacuum to form a display electrode.

The transparent electrode thus formed exhibits low resistance characteristics equivalent to 3 Ω / □ and has a transmittance of 80 at 550 nm.
% Or more, showing excellent characteristics.

(Embodiment 5) FIG. 9 is a constitutional view showing a cross section of a terminal portion of a color STN liquid crystal display element for explaining a display element according to the present invention, in which a transparent electrode is formed on a lower surface of an upper transparent substrate 7. An ITO thin film 2 is provided, and an alignment film 8 is sequentially formed on the ITO thin film 2. A color filter 5 and a smoothing layer 6 are sequentially provided on the upper surface of the lower transparent substrate 1 facing each other, and a multilayer thin film electrode of ITO thin film 2 / silver thin film 3 / ITO thin film 2 is formed in this order. The film thickness is 500Å / 150Å / 500Å respectively. This multilayer structure is formed only inside the lower portion of the sealing material 11, and the terminal connecting electrode portion projecting outside from the sealing material 11 has only the lower ITO thin film 2.

The liquid crystal display device thus formed was subjected to a standing test in constant temperature and high humidity (60 ° C./90%). Almost no change was seen in the formed multilayer thin film electrode,
It was confirmed that there were no problems in actual use. When the multilayer thin film structure was formed up to the terminal portion as in the conventional case, the adhesion force at the interface between the silver thin film and the ITO film was reduced after 100 hours in constant temperature and high humidity, and peeling or swelling was observed. Therefore, it was found that the conventional method cannot withstand actual use.

In the above description, as a multilayer thin film electrode,
Although it has a multilayer structure of ITO thin film / silver thin film / ITO thin film, a transparent conductive film may be used as the first transparent thin film from the substrate side. The metal thin film of the second layer may be silver, copper, or an alloy thereof. The metal thin film of the third layer may be any transparent thin film having good adhesion to the base, such as In ₂ O ₃ , TiO ₂ , ZrO ₂ and Ta.
₂ O ₅ , Al ₂ O ₃ , Bi ₂ O ₃ and SiO ₂ are used.

[0037]

As described above, according to the method of manufacturing an electrode substrate and the display device using the electrode substrate of the present invention,
Since a multi-layer thin film electrode sandwiching a metal thin film can be used as a display electrode of a display element, the effect of lowering the resistance can improve display unevenness such as crosstalk and brightness gradient even in a large screen or a high definition screen. Moreover, since the multilayer film structure is formed inside the sealing material of the display device, it is possible to provide a display element having excellent environmental reliability and no problem in actual use.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a method of manufacturing an electrode substrate according to a first embodiment of the present invention.

FIG. 2 is a process drawing of the manufacturing method of the electrode substrate according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram of a method of manufacturing the electrode substrate according to the second embodiment of the present invention.

FIG. 4 is a process drawing of the manufacturing method of the electrode substrate according to the second embodiment of the present invention.

FIG. 5 is a schematic diagram of a method of manufacturing an electrode substrate according to a third embodiment of the present invention.

FIG. 6 is a process drawing of the manufacturing method of the electrode substrate according to the third embodiment of the present invention.

FIG. 7 is a schematic diagram of a method of manufacturing the electrode substrate according to the fourth embodiment of the present invention.

FIG. 8 is a process drawing of the manufacturing method of the electrode substrate according to the fourth embodiment of the present invention.

FIG. 9 is a sectional view of a terminal portion of a color STN liquid crystal display element according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view of a terminal portion of a conventional color liquid crystal display element.

FIG. 11 is a plan view of a color filter when a conventional multilayer thin film electrode is used.

FIG. 12 is a cross-sectional view of a color filter when a conventional multi-layer thin film electrode is used.

[Explanation of symbols]

1 ... Transparent substrate, 2 ... ITO thin film (transparent electrode), 3 ... Silver thin film, 4 ... Resist, 5 ... Color filter, 6 ...
Smoothing layer, 7 ... Transparent substrate, 8 ... Alignment film, 9 ... Spacer, 10 ... Liquid crystal layer, 11 ... Sealing material.

Claims (7)

[Claims] 1. A step of forming a multi-layered transparent conductive thin film sandwiching a metal thin film on a transparent substrate, and a step of selectively etching the multi-layered transparent conductive thin film in a predetermined pattern up to the metal thin film layer. And a step of processing the selectively etched transparent conductive thin film into a predetermined electrode pattern. 2. A step of forming a transparent conductive thin film on a transparent substrate, a step of forming a metal thin film in a predetermined pattern on the transparent substrate, and a step of forming a transparent metal oxide film on the transparent substrate. And a step of processing the transparent conductive thin film having a multi-layered structure on the transparent substrate into a predetermined electrode pattern. 3. A step of forming a multi-layered transparent conductive thin film sandwiching a metal thin film on a transparent substrate; a step of processing the multi-layered transparent conductive thin film into a predetermined electrode pattern; A method of manufacturing an electrode substrate, comprising a step of selectively etching a metal thin film layer in a pattern. 4. A step of forming a predetermined resist pattern on a transparent substrate, a step of forming a transparent conductive thin film on the transparent substrate, and forming a metal thin film and a metal oxide film on the transparent substrate in a predetermined pattern. And a step of forming an electrode pattern by removing the resist, a method of manufacturing an electrode substrate. 5. The transparent substrate is a substrate having a color filter layer formed thereon.
4. The method for manufacturing an electrode substrate according to any one of 4 above. 6. A display device using the electrode substrate manufactured by the method for manufacturing an electrode substrate according to claim 1, wherein a transparent electrode having a multilayer structure including a metal thin film is mounted on a mounting terminal. A display element characterized in that it is configured so as not to extend into a portion. 7. The display device according to claim 6, wherein the display portion has a liquid crystal display structure.