JPS61179093A - Manufacture of thin film el panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a method for manufacturing multicolored thin film EL elements used for character and graphic displays.

Prior Art Recently, ZnS:Mn has been used as a phosphor thin film layer for thin film EL devices.
Other materials with high brightness have also been developed. For example, ZnS:TbF is green, ZnS:SmF3
SrS:Co emits bright red light, and SrS:Co emits blue light. Thin film EL devices with multicolor display using these materials have been proposed. When producing a thin film EL device with multicolor display, it is necessary to arrange a plurality of phosphor thin film layers in a predetermined pattern. If the pattern is large, a metal mask can be used to form each phosphor thin film layer. If the pattern is too fine, it is practically impossible to form it using a metal mask, so another method must be used.

If an electrode layer and, if necessary, a dielectric thin film layer are sandwiched between each phosphor layer, each phosphor thin film layer can be formed uniformly over the entire surface, but the device structure becomes very complicated. The characteristics are unstable. An element having a structure in which each phosphor thin film layer is formed on the same plane is practical from the viewpoint of structural simplicity and stability of characteristics.

To form a single thin film layer into a fine pattern, a common method is to form a thin film uniformly over the entire surface, then form a photoresist pattern, and then chemically or physically remove unnecessary parts of the thin film. be. However, when forming a plurality of phosphor thin film layers on the same plane, the following difficulties arise. 1st
When the properties of the phosphor thin film layer and the second phosphor thin film layer are similar,
It is virtually impossible to uniformly remove only the second phosphor thin film layer placed on the first phosphor thin film layer over the entire surface of the device. The first phosphor thin film layer is partially removed,
A second phosphor thin film layer remains.

As a way to avoid this problem, for example,
There are 123,193 methods. That is, after uniformly forming a light emitting matrix thin film layer such as ZnS, a plurality of types of rare earth metal ions are implanted by ion implantation using a photoresist as a mask material to obtain a predetermined pattern.

Problems to be Solved by the Invention In such conventional methods, luminescent impurities are added after forming a thin film of a luminescent matrix material, so the luminous efficiency is lower than that of an original phosphor thin film layer in which both are formed at the same time. It has the disadvantage of being low. Furthermore, the ion implantation equipment is bulky and expensive.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for forming a plurality of phosphor thin film layers having original luminous efficiency values on the same plane without requiring expensive equipment.

Means to Solve the Problem A metal thin film layer was laminated on the first phosphor thin film layer and both layers were formed in a predetermined pattern. , by dissolving the metal thin film layer.
The second phosphor thin film layer on the phosphor thin film pattern is removed by a lift-off method to form a plurality of types of phosphor thin film layers in a predetermined pattern.

Function: Since the phosphor thin film layer is formed in a predetermined turn using the lift-off method, the luminescent impurity can be added from the beginning during the formation of the luminescent matrix film, so the luminous efficiency of the phosphor thin film is high.Moreover, The metal thin film layer can be easily removed without affecting the first phosphor thin film layer.

Embodiment FIGS. 1 to 6 show a method for manufacturing a thin film EL device of the present invention.

First, as shown in FIG. 1, an IT○
A film 2 is formed by DC sputtering, and a 5rTi*3 film is formed thereon as a dielectric film 2 by RF sputtering. The substrate temperature was 400°C. As a first phosphor thin film layer, a ZnS:Tb, P film 4 is uniformly formed over the entire surface by RF sputtering. Substrate temperature is 200℃
It is. Next, Zn
The substrate formed on the S:Tb,P film 4 is not heated. The thickness of each film is 300 nm for the ITO film 2 and 500 nm for the dielectric film 3.

The ZnS:Tb, P film has a thickness of 400 nm, and the yttrium film 6 has a thickness of 1 μm. As shown in FIG. 2, one photoresist layer 6 is formed and formed into a predetermined pattern by photolithography. The pattern pitch is 400
It is μm. Next, the yttrium film 6 and ZnS:Tb were formed using a mixed acid of phosphoric acid, acetic acid, and nitric acid.

The P film 4 is etched. FIG. 3 shows the state with the photoresist layer 6 removed. As shown in FIG. 4, a ZnS:am,P film 7 constituting the second phosphor thin film layer is formed thereon by RF sputtering to a thickness of 400 nm. The substrate temperature is 230°C. The substrate is immersed in dilute hydrochloric acid to dissolve the yttrium film 5 and the ZnS on it:
The Sm and P films are removed by the 7-off method. In this way, as shown in FIG. 5, a ZnS:Tb, P film 4 and a ZnS:Sm, P film 7 were formed in a predetermined pattern on the SrT 103 film 3.

Next, as shown in FIG. 6, after annealing in vacuum, Y2o
3 film 8 and BaTa 20s film 9 were formed by EB evaporation and RF sputtering, respectively. Each film thickness is 2
5 nm and 50 nm. Finally, an At electrode 10 was formed to complete a thin film EL device. When this device was driven, the same luminous efficiency as an EL device formed using each phosphor alone was obtained. The reason why the metal thin film layer was used for lift-off without using the 7-photoresist is that the metal thin film layer is stable against the substrate heating required when forming the second phosphor thin film layer. During lift-off, it is necessary to use an etchant that has a much higher rate of dissolution of the first and second phosphor thin film layers and the metal thin film layer. Aluminum, zinc, indium, yttrium, tin, antimony, and rare earth metal elements dissolve very quickly in acids such as dilute hydrochloric acid. These metals are preferable because they have almost no adverse effect on the luminescent properties of phosphor materials used in EL, such as ZnS. Further, according to the present invention, it is also possible to form a plurality of types of phosphor thin film layers using different types of luminescent host materials on the same plane.

Furthermore, it goes without saying that the present invention is also effective when three or more types of phosphor thin film layers are formed.

Effects of the Invention According to the present invention, a plurality of phosphor thin film layers with original luminous efficiency can be formed on the same plane, and a bright multicolored thin film EL can be produced.
It is possible to provide an element.

[Brief explanation of the drawing]

1 to 6 are cross-sectional views showing a method of manufacturing a thin film EL device according to an embodiment of the present invention. 1...Glass substrate, 2...Transparent electrode,
3... Dielectric thin film layer, 4... First phosphor thin film layer, 6... Metal thin film layer, 6...
・7 Otoresist layer, 7... Second phosphor thin film layer, 8, 9... Dielectric thin film layer, 1°...
・At electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Figure 5

Claims (2)

[Claims] (1) A method for manufacturing a thin film EL device comprising a light emitting layer formed on a substrate and electrode layers sandwiching the light emitting layer, which includes a step of forming a first phosphor thin film layer over the entire display area, and a step of forming a metal thin film layer over the entire display area. a step of forming the first phosphor thin film layer on the first phosphor thin film layer;
a step of removing a part of the phosphor thin film layer and the metal thin film layer to form a predetermined pattern; a step of forming a second phosphor thin film layer over the entire display area; The second phosphor thin film layer on the metal thin film layer is removed by a lift-off method by melting, and the second phosphor thin film layer is formed into a predetermined pattern. A method for manufacturing a thin film EL element. (2) The metal thin film layer is made of at least one selected from aluminum, zinc, indium, yttrium, tin, antimony, and rare earth metal elements. A method for manufacturing a thin film EL element.