JP2008226494A - Electrode and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode having low reflection and low resistance, which can be formed by a simple method. <P>SOLUTION: This electrode 17 has an transparent electrode 12 formed in a prescribed pattern on a substrate 11. An Al thin film 15 containing aluminum a portion of which is electrically connected to the transparent electrode is provided on the transparent electrode, and a Cr thin film 16 containing chromium is formed on the AL thin film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrode formed on a display screen side in a display device such as an EL (electroluminescence) display element or a PDP (plasma display panel). The present invention also relates to a display device.

  As shown in FIG. 3, a general thin film EL element applies a plurality of stripe-shaped back electrodes 52 parallel to the first direction, an insulating layer 53 having a high dielectric constant, and an electric field on an insulating substrate 51. Thus, a phosphor layer 54 that emits light, an insulating layer 55 having a high dielectric constant, and a plurality of striped transparent electrodes 56 parallel to the second direction orthogonal to the first direction are provided in this order. By applying a voltage between the back electrode 52 and the transparent electrode 56, the phosphor layer 54 emits light at the intersection of the back electrode 52 and the transparent electrode 56, and this light passes through the transparent electrode 56 and passes through the image. Is displayed. As the transparent electrode 56, a material such as ITO having low resistance and high transparency is used. However, the resistance value is not sufficiently small, causing problems such as an increase in power consumption. Therefore, an auxiliary electrode (bus electrode) 57 is formed as a resistance auxiliary electrode in electrical contact with the transparent electrode 56.

  Al, Cu, Au, Ag, etc., which are good electrical conductors, are widely used as electrodes and wiring materials for display devices such as EL display elements and PDPs. However, since these materials have high light reflectance, when these materials are used as an electrode material formed on the display screen side like the auxiliary electrode 57, external light is reflected and the contrast of the image is lowered. The problem arises.

In order to solve this problem, Patent Document 1 proposes a black electrode in which a good conductor Al thin film and a metal oxide thin film containing Al and Mo are laminated. Patent Document 2 proposes a black electrode containing a ruthenium-based polyoxide. Since these black electrodes used as the light reflection suppressing layer are made of metal oxide and have high heat resistance, they can withstand heat treatment in the manufacturing process after electrode formation.
JP-A-2-306505 JP 2004-158456 A

  However, when heat treatment is not required after electrode formation, the black electrode does not need to have high heat resistance, and therefore, a low-reflective and low-resistance electrode that can be formed at a lower cost and with a simple construction method is provided. Desired.

  The electrode of the present invention comprises an Al thin film containing aluminum formed on a transparent electrode formed in a predetermined pattern on a substrate, at least a part of which is electrically connected to the transparent electrode, and the Al thin film. And a Cr thin film containing chromium formed on the substrate.

  The display device of the present invention includes the above-described electrode of the present invention.

  According to the present invention, it is possible to provide an electrode that can be formed by a simple method and has both low reflectivity and high conductivity.

  When this electrode is used as an electrode formed on the display screen side of the display device, external light reflection can be suppressed and the contrast of image quality can be improved.

  The electrode of the present invention includes an Al thin film made of aluminum or a metal compound containing aluminum and a Cr thin film made of chromium or a metal compound containing chromium and electrically connected to a transparent electrode formed on the substrate. Thereby, the electrode can be blackened when viewed from the front substrate side (Cr thin film side), and reflection of light on the electrode surface can be suppressed. In addition, the resistance value of the electrode can be kept as low as Al.

  The experimental result performed in order to confirm the effect of the electrode of this invention is shown.

  In a vacuum atmosphere, an Al thin film having a film thickness of about 300 nm is formed on a substrate by a normal vacuum vapor deposition using a small Al piece, and a Cr thin film having a film thickness of about 40 nm is formed by a normal vacuum vapor deposition using Cr grains on the Al thin film. Were formed continuously. The spectral reflectance of the electrode composed of the obtained two-layer laminated film was measured. For comparison, an electrode composed of three types of two-layer laminated films formed in the same manner as above except that the film thickness of the Cr thin film is changed to about 10 nm, about 30 nm, and about 100 nm, and an Al film with a film thickness of about 300 nm on the substrate. A single layer electrode in which only a thin film is formed in the same manner as described above and a single layer electrode in which only a Cr thin film having a thickness of about 40 nm is formed in the same manner as described above on a substrate are formed, and the respective spectral reflectances are determined. It measured similarly. The results are shown in FIG.

  As shown in FIG. 1, the reflectance of the two-layer laminated film composed of the Al thin film and the Cr thin film is greatly reduced in the entire visible light with a wavelength of 400 to 800 nm as compared with the single layer film composed of only the Al thin film. Furthermore, the two-layer laminated film in which the Cr thin film has a thickness of about 30 nm, about 40 nm, or about 100 nm has substantially the same or smaller reflectance than the single layer film made of only the Cr thin film.

  When the film thickness of the Cr thin film exceeds 100 nm in the two-layer laminated film composed of the Al thin film and the Cr thin film, the reflectance of the electrode surface approaches that of the single layer film composed of only the Cr thin film, and the light reflection suppressing effect is small. Become. Further, when the film thickness of the Cr thin film is less than 10 nm in the two-layer laminated film composed of the Al thin film and the Cr thin film, the influence of the reflection on the Al thin film is increased, and the light reflection suppressing effect is similarly reduced. As a result of repeated experiments by the present inventors, the film thickness of the Cr thin film is within the range of 10 to 100 nm in order to obtain a good light reflection suppressing effect in the two-layer laminated film composed of the Al thin film and the Cr thin film. Preferably, about 40 nm has been found to be optimal.

  From the above-mentioned two-layer laminated film consisting of an Al thin film with a thickness of about 300 nm and a Cr thin film with a thickness of about 40 nm, a single layer film consisting only of an Al thin film with a thickness of about 300 nm, and a Cr thin film with a thickness of about 300 nm The resistance value of the resulting single layer film was measured. The results are shown in Table 1.

  From Table 1, it can be seen that the two-layer laminated film composed of the Al thin film and the Cr thin film has a low resistance value equivalent to that of the single layer film composed of only the Al thin film.

  In the above experiment, a two-layer laminated film composed of an Al thin film and a Cr thin film was directly formed on the substrate, but the adhesion between the substrate and the Al thin film was not sufficient, and an electrode was formed by a lift-off method using a photoresist. In some cases, it may be difficult to form electrodes in the fine line pattern. In such a case, it is preferable that a Ti thin film made of titanium or a metal compound containing titanium is formed on the substrate as a first layer, and an Al thin film and a Cr thin film are sequentially laminated thereon. With such a three-layer electrode, the adhesion of the electrode is improved and the patterning property is improved, so that an electrode with a high-definition pattern can be easily formed.

  An example of a method for manufacturing an EL display element provided with the electrode of the present invention will be described with reference to FIG. However, the following is only an example, and it goes without saying that the present invention is not limited to this.

  First, as shown in FIG. 2A, a substrate 11 is formed in which a plurality of striped back electrodes, insulating layers, and phosphor layers are formed in this order on an insulating substrate. Next, a plurality of striped transparent electrodes 12 made of ITO or the like are formed on the substrate 11 at a predetermined line width and interval. Here, the extending direction of the plurality of transparent electrodes 12 is orthogonal to the extending direction of the plurality of striped back electrodes. Next, a pattern of the photoresist 13 is formed with a predetermined line width and interval. Next, a Ti thin film 14 having a thickness of about 200 nm is formed on the entire surface by vacuum deposition, an Al thin film 15 having a thickness of about 300 nm is formed on the Ti thin film 14 by vacuum deposition, and vacuum deposition is further performed on the Al thin film 15. Thus, a Cr thin film 16 having a thickness of about 40 nm is formed. The three-layer laminated film composed of the Ti thin film 14, the Al thin film 15, and the Cr thin film 16 is continuously formed while maintaining a vacuum atmosphere. The Al thin film 15 is formed such that at least a part thereof is electrically connected to the transparent electrode 12. Next, the photoresist 13 is removed. As a result, as shown in FIG. 2B, an EL display element is obtained in which the auxiliary electrode 17 composed of the Ti thin film 14, the Al thin film 15, and the Cr thin film 16 is formed on the transparent electrode 12.

  In the above, materials and forming methods of the back electrode, the insulator layer, the phosphor layer, and the transparent electrode are not particularly limited, and known materials and methods for the EL display element can be appropriately selected and used. For example, in the case of an inorganic EL display element, an inorganic dielectric layer can be used as the insulator layer, and an inorganic phosphor layer can be used as the phosphor layer.

  Although there is no restriction | limiting in particular in the electrode utilization field of this invention, For example, it can utilize as an electrode formed in the display surface side of display apparatuses, such as an EL display element and PDP.

FIG. 1 is a diagram showing the measurement result of the spectral reflectance of the electrode. 2 (A) and 2 (B) are cross-sectional views sequentially showing the outline of the method for producing an electrode of the present invention. FIG. 3 is a cross-sectional view showing a schematic configuration of a general EL display element.

Explanation of symbols

11 Substrate 12 Transparent electrode 13 Photoresist 14 Ti thin film 15 Al thin film 16 Cr thin film 17 Auxiliary electrode 51 Insulating substrate 52 Back electrode 53 Insulating layer 54 Phosphor layer 55 Insulating layer 56 Transparent electrode 57 Auxiliary electrode

Claims (4)

  An Al thin film containing aluminum formed on a transparent electrode formed in a predetermined pattern on a substrate and at least a part of which is electrically connected to the transparent electrode, and chromium formed on the Al thin film. An electrode comprising a Cr thin film.   The electrode according to claim 1, further comprising a Ti thin film containing titanium between the transparent electrode and the Al thin film.   The electrode according to claim 1 or 2, wherein the Cr thin film has a thickness in a range of 10 nm to 100 nm.   The display apparatus using the electrode in any one of Claims 1-3.

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