JPH03210789A - Thin film el element - Google Patents

Abstract

PURPOSE:To simplify a work process by concurrently forming both outer leading terminal electrodes of transference and back electrodes by electroless plating. CONSTITUTION:An ITO film is formed on a translucent substrate 1, stripelikely processed, and a pattern is formed to obtain a strip-like transference electrode 2. An oxide dielectric film is formed as a dielectric layer 3 on the transference electrode 2, an EL emitter layer 4 is formed on the dielectric layer 3, and after heat treatment, an oxide dielectric film is formed as a dielectric layer 5. Moreover an Al film is vacuum-evaporated, to both of an effective display part and an outer leading terminal electrode part, on the dielectric layer 5, and then stripe-likely processed to form the lower layer film 11 of a back electrode 6 and outer leading terminal electrodes 9 and 10. The upper layer film 12 of the electrodes 9 and 10 is formed by electroless plating, and has a main component of Ni including at least 0.1% of B. The electrodes 9 and 10 of the thin film EL element and the terminal electrode of an outer circuit are connected together by soldering.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a thin film EL element used for displaying characters, graphics, etc., and more specifically to the structure of an external lead terminal electrode of a thin film EL element.

2. Description of the Related Art XY matrix type solid-state image display devices using electroluminescent phosphors have been known. This device arranges a group of horizontal parallel electrodes and a group of vertical parallel electrodes on both sides of an electroluminescent layer so as to be orthogonal to each other, and applies a signal through an external drive circuit using a power supply line connected to each electrode group to produce an image. The electroluminescent layer (hereinafter referred to as EL emitter layer) at the intersection of the electrode groups is caused to emit light (this intersection area is referred to as a picture element).
, characters, symbols, figures, etc. are displayed by a combination of emitted picture elements.

Figures 4 and 5 show the cross-sectional structure of a conventional thin film EL element.The display plate of the solid-state image display device used here is usually a group of transparent horizontal parallel electrodes on a transparent substrate l such as glass. A transparent electrode 2 is formed, and a first dielectric layer 3, an EL layer, a light emitting layer 4, and a second dielectric layer 5 are sequentially laminated thereon, and a back electrode 6, which is a group of vertically parallel electrodes, is formed on top of the transparent electrode 2. are laminated in an arrangement perpendicular to the lower transparent electrode 2.

- Generally, the transparent electrode 2 is formed by depositing tin oxide or tin-doped indium oxide (hereinafter abbreviated as ITO) on a smooth light-transmitting substrate l and patterning it into a desired shape. A back electrode 6 perpendicular to this and facing
It is formed by forming a film by vacuum evaporation or the like and patterning it into a desired shape. Here, soldering is generally used as a method for connecting the transparent electrode 2 and the back electrode 6 to an external circuit. However, both ITO of the transparent electrode 2 and Al of the back electrode 6 have poor solderability. Therefore, one method for making the external lead terminal electrode 7 of the transparent electrode 2 and the back electrode 6 is to pattern the back electrode 6. After the process is completed, a striped metal film 7 (for example, Ni/Cr) is formed by vacuum evaporation using a metal mask in which striped windows are formed (FIG. 4), or another method. As, A for the back electrode 6
After forming the f film, a metal film 8 (for example, Ni) for the external lead-out terminal electrode is subsequently formed around the periphery, a resist pattern for etching is formed, and the back electrode 6 and the external lead-out terminal electrode are formed by wet etching. Form the pattern sequentially (
(Fig. 5) is used.

Problems to be Solved by the Invention Methods using metal masks (+) cannot produce high definition images, (2) are not suitable for large screens, (3) are difficult to handle metal masks, (4) lower electrodes (There is a problem that alignment with the transparent electrode 2 and the back electrode (6) is difficult.In addition, in the wet etching method, (1)
The metal film for the external lead terminal electrode 7 must be formed only around the EL element, so after forming the metal film for the back electrode 6, a mask for film formation that covers the effective display area is used. There are problems such as (2) etching has to be performed for the number of metal films that have been formed, which makes the process complicated.

Means for Solving the Problems According to the present invention, a thin film EL is produced by sequentially laminating a transparent electrode, a first dielectric layer, an EL light emitting layer, a second dielectric layer and a back electrode on a transparent substrate. In the device, when forming the metal film for the back electrode, the same film is also formed on the external lead terminal electrode part to form a pattern, and then the external lead terminal electrodes of both the transparent electrode and the back electrode are formed. It can be formed by laminating films containing Ni as a main component by electrolytic plating.

Both the working transparent electrode and the back electrode, which lead out to the outside, can be formed simultaneously by electroless plating. Moreover,
The top layer film formed by plating is made of N, which has good soldering properties.
Since the film is mainly composed of i, it can be connected to an external circuit by soldering.

Embodiment FIGS. 1 and 2 are cross-sectional views showing the structure of the back electrode and the external lead-out terminal electrode portion of the transparent electrode of a thin film EL element according to the present invention, and FIG. 3 is a plan view thereof. ,
In FIGS. 2 and 3, 1 is a transparent substrate;
2 is a transparent electrode.

A first dielectric layer 3, an EL light emitter layer 4, a second dielectric layer 5, and a back electrode 6 are formed thereon.

The first external lead terminal electrode 9 of the transparent electrode 2 and the second external lead terminal electrode 10 of the back electrode 6 are formed so as to partially overlap the transparent electrode 2 and the back electrode 6, respectively. Then, the first and second external lead-out terminal electrodes 9.1
The lower layer film 11 of 0 is the same film as the back electrode 6, and the upper layer film 1
2 is a film mainly composed of Ni, which was formed by an electroless plating method.

Next, the light-transmitting substrate 1, which will be described as a specific example, is a glass substrate, and 7059 glass manufactured by Corning Co., Ltd. was used. In addition, the size of the transparent substrate l is 240cm and the thickness is 1
．． It is a palace. ITO with a thickness of 600 nm was deposited on a transparent substrate 1 by direct current sputtering at a substrate temperature of 400''C and a gas pressure of 0.8 Pa (partial pressure ratio of argon to oxygen 4:1).
A film was formed. At this time, the resistivity of ITolfi is 2
．． The ITO film was then processed into a stripe shape using photolithography. A pattern with a width of 0°23 cm was formed with a pattern interval of 0.3 cm. In this way, the stripe-like A transparent electrode 2 was formed on which a sintered body of strontium zirconate titanate [Sr (TiXZr+-x)03] was sputtered at a substrate temperature of 400°C to a thickness of 300°C.
nm of the oxide dielectric film having the above composition formula as the first dielectric layer 3
Formed as. Furthermore, an EL light emitting layer 4 made of a manganese-doped zinc sulfide film having a thickness of 500 nm was formed thereon by co-evaporation at a substrate temperature of 200''C.
After heat treatment at 50°C for 1 hour, a barium tantalate [BaTa2O6] sintered body was placed thereon at a substrate temperature of 150°C.
An oxide dielectric film having a thickness of 300 nm was formed as the second dielectric layer 5 by sputtering.

Furthermore, an Affi film with a thickness of 150 nm was vacuum-deposited on both the effective display area and the external lead-out terminal electrode area, and the A! The film is processed into stripes by photolithography, and a back electrode 6 and first and second external terminal electrodes 9 are formed. The lower layer of IO @11 was formed.

Upper layer film 1 of first and second external lead-out terminal electrodes 9 and 10
No. 2 was formed by an electroless plating method. Electroless Ni used
The plating liquid has a B content of about 1%. Metsuki temperature 30
When plating was performed at °C for about 8 minutes, a Ni plating film with a thickness of 300 nm was obtained. In addition, during plating, unnecessary portions of plating were masked with resist.

A good connection was obtained when the external lead-out terminal electrodes 9 and 10 of the fil14EL element created as described above were connected to the terminal electrodes of the external circuit (Cu foil pattern with Sn plating) by soldering. was completed.

Regarding the content of B, 1% was used in the example, but when considering the stability of the plating film, it should be at least 0.1%.
It is sufficient if it contains %.

Effects of the Invention As described above, according to the present invention, when forming the metal film for the back electrode, the same film is also applied to the external lead terminal electrode portion of both the transparent electrode and the back electrode. After forming a film and forming a pattern, Ni is deposited by electroless plating method.
Because it can be formed by laminating films whose main components are
This can contribute to reducing the manufacturing cost of the L element.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a thin-film EL panel according to the present invention, FIG. 3 is a plan view of a thin-film EL panel according to the present invention, and FIGS. 4 and 5 are cross-sectional views of a conventional thin-film EL panel. It is a diagram. 1...Transparent substrate, 2...Transparent electrode,
3...First dielectric layer, 4...EL light emitter layer, 5...Second dielectric layer, 6...Back electrode, 9... ...First external lead-out terminal electrode, 10
...Second external lead-out terminal electrode, 11...
Top N film, 12... bottom layer film.

Claims (1)

[Claims] In a thin film EL device in which a transparent electrode, a first dielectric layer, an EL light emitter layer, a second dielectric layer, and a back electrode are sequentially laminated on a light-transmitting substrate, an external surface of the transparent electrode and the back electrode is provided. The lead-out terminal electrode is made of a laminated metal film,
and the lowermost layer of the laminated film is formed of the same film as the back electrode, and the uppermost layer is formed of a film mainly composed of Ni containing at least 0.1% B and formed by an electroless plating method. A thin film EL device characterized by the following.