JPH02152192A - Manufacturing method of multicolor thin film EL device - 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 a multicolor thin film EL device, and in particular to a method for manufacturing a multicolor thin film EL device, in particular a method for manufacturing a multicolor thin film EL device, in which the luminance is uniform over a wide area, from a low brightness region to a high brightness region. The present invention relates to a method for manufacturing a thin film EL element.

2. Description of the Related Art In recent years, thin film EL devices have been actively researched as flat displays used in computer terminals and the like. Such a thin film EL element is formed as follows.

A tin-doped indium oxide (ITO) thin film is deposited on a glass substrate, and a striped transparent electrode is formed by a photolithography process. 5i2Na on top of that, Ya 03 s
A first insulating layer made of 5rTi05 or the like is formed by vacuum evaporation or sputtering.

Subsequently, on the first insulator layer, for example ZnS:Tb, F
A green light-emitting phosphor thin film consisting of is formed by vacuum evaporation or sputtering. Next, it is processed into stripes by a photolithography process as shown in FIG. 3, and after removing the photoresist, a red light-emitting phosphor thin film made of, for example, CaS:Eu is formed by vacuum evaporation or sputtering. Thereafter, it is processed into stripes by a photolithography process as shown in FIG. 4, and after removing the photoresist, a blue-emitting phosphor thin film made of, for example, SrS:Ce is formed by vacuum evaporation or sputtering. Then, it is processed into stripes by a photolithography process as shown in FIG. 5, and the photoresist is removed to complete the luminescent layer. Next, Si: + N4, Y2 (h, 5
A second insulating layer made of rTi02 or the like is formed by vacuum evaporation or sputtering, and finally a back electrode made of striped A1 thin film in a direction perpendicular to the transparent electrode is formed to complete the thin film EL device. (For example, the technique described in Japanese Patent Application No. 63-46192).

Problems to be Solved by the Invention When thin film EL elements are formed using conventional techniques, there is a problem in that the emission start voltage varies slightly depending on the location even within the same substrate, and uneven emission occurs, especially at low brightness levels. Ta. Therefore, the display quality during gradation display was insufficient, and there was a particular problem in full color display.

The object of the present invention was invented in view of the above problems, and it is an object of the present invention to provide a method for manufacturing a multicolor thin film EL element with uniform luminance over a wide area.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a light-emitting layer in which a transparent electrode, an insulating layer, and two or more types of phosphor thin films are arranged on the same plane on a transparent substrate; In a method for manufacturing a multicolor thin film EL device formed by laminating electrodes, etc., when forming the luminescent layer, a phosphor thin film is formed, and then a photoresist is used to perform etching into an arbitrary pattern, and the photoresist is removed. After that, the entire surface of the substrate including the surface of the phosphor thin film is etched by irradiating accelerated ions or atoms.

Function One of the causes of local differences in luminescence starting voltage within the same substrate is the difference in the surface condition of the phosphor thin film, and this difference in surface condition may be caused by, for example, contamination by the photoresist or a metal element contained in the photoresist. However, according to the present invention, by etching the entire surface of the substrate including the surface of the phosphor N film using accelerated ions or atoms, the surface condition can be made homogeneous, and the luminance can be increased over a wide area. A uniform thin film EL device can be manufactured.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a flowchart for explaining one embodiment of the manufacturing method of the present invention, and FIG. 2 is a sectional view of the device structure. An ITO thin film with a thickness of 300 nm was formed on a glass substrate 1 by sputtering. Next, a striped transparent electrode 2 was formed using a photolithography process consisting of resist coating, exposure, development, etching, resist removal, and the like.

On top of that, in an argon atmosphere containing 10% oxygen,
A first insulating layer 3 having a thickness of 500 nm was formed by subjecting 5rTi03 to RF spa-tumering at a substrate temperature of 1.5°C.

A 560 nm thick phosphor thin film made of ZnS:Tb was formed on the first insulator layer 3 by electron beam evaporation, and then heat treated at 500'C in vacuum for 1 hour. This ZnS:Tb thin film was processed into a third layer using a photolithography process.
A striped green light emitter layer 4 as shown in the figure was formed. After removing the photoresist 7, the substrate was placed on the cathode of a dry etching device, and sputter-etched for 5 minutes at an RF power of 500 in an argon gas atmosphere containing 102 oxygen at 1xlO-2 Torr.
The surface was etched by approximately 30 nm. Subsequently, a phosphor thin film made of CaS:Eu with a thickness of 530 ns+ was formed by electron beam evaporation, followed by heat treatment at 500° C. for 1 hour in vacuum. This CaS:Eu thin film was used to form a striped red light emitter layer 5 as shown in FIG. 4 using a photolithography process. After removing the photoresist 8,
Place the substrate on the cathode and apply 10
In an argon gas atmosphere containing oxygen of z, rf power 5
Sputter etching was performed at 00 W for 5 minutes, and the surfaces of the green light emitter layer 4 and the red light emitter layer 5 were etched by about 30 nm. Subsequently, the thickness was 500nIll by electron beam evaporation method.
A phosphor thin film made of SrS:Ce was formed and then heat treated in vacuum at 500° C. for 1 hour. This SrS:C
A striped blue light emitter layer 6 as shown in FIG. 5 was formed on the E thin film using a photolithography process. After removing the photoresist 9, place the substrate on the cathode and
Sputter etching was performed for 5 minutes at an RF power of 500 W in an argon gas atmosphere containing a lot of oxygen at O-2 Torr, and the surface of the luminescent layer 4.5.6 was etched by about 30 r+a+.

Finally, a second insulating layer 1 made of Y2O3 with a thickness of 200 ni+ is deposited on the light emitting layer 4.5.6 by electron beam evaporation.
A thin film EL device was completed by sequentially forming striped back electrodes 11 made of AI of 0 and 15001.

Luminance at 60Hz of the thin film EL device obtained above -
As for the voltage characteristics, a difference in emission start voltage of 5 V or less was obtained within the entire emission region of 100x20On+112. Furthermore, the light emission state was also uniform from the low voltage region to the high voltage region. In comparison, in the device in which the second insulating layer 10 was formed without sputter-etching the surface of the light emitter layer, the light emission start voltage varied depending on the location, and some parts exhibited non-uniform light emission. Moreover, minute peeling sometimes occurred in the phosphor thin films formed the second and third times. Such variations in characteristics in conventional manufacturing methods are due to non-uniformity on the surface of the light emitter layer and the surface of the first insulator layer. Possible contamination. In the manufacturing method of the present invention, the non-uniformly altered parts on the surface of the light emitter layer and the surface of the first insulator layer are etched away by accelerated ions, so there is no peeling or contamination over a wide area.
A homogeneous emitter layer surface is obtained, resulting in uniform brightness.
It is thought that the voltage characteristics were obtained. A wet etching method using MCI or H2SO4 is usually used as an etching method for the phosphor layer. However, in this method, the etching rate is large in the altered parts of the phosphor layer surface (in contrast, It was not possible to remove a uniform thickness.

In this example, the etching method for the luminescent layer is r.
Although the f-sputter etching method is used, the present invention can be practiced with any other etching method that utilizes collisions of accelerated ions or atoms, such as ion beam sputter etching method.

Although argon gas containing 10 ions of oxygen as etching ions or atoms was used, rare gas or oxygen gas may be used alone, or a mixture of other rare gases and oxygen gas may be used. The effects of the present invention could be demonstrated.

However, when oxygen was included, the reproducibility of the homogeneity of the light emission state was better.

The etching depth of the emitter layer by accelerated ions or atoms is effective when the etching depth is 5 times or more, and as the depth increases, the magnitude of the effect tends to be saturated;
I am completely saturated with this.

Furthermore, in this example, a method for manufacturing a double insulating layer type thin film EL element was explained, but for example, when manufacturing a single side insulating layer type thin film EL element without using the first insulating layer, or when manufacturing a DC type EL element without using an insulating layer, Of course, the effects of the present invention can also be exerted on thin film EL elements. Furthermore, a thin insulating thin film is formed immediately before forming the second and third phosphor thin films, and the thin film E has a structure that serves as an over-etching prevention layer when etching the second and third phosphor thin films.
The effects of the present invention could also be exhibited in the L element. In other words, the effects of the present invention can be exerted in all thin film EL device manufacturing methods that include the step of forming a phosphor thin film and then applying a resist to the surface thereof.

Effects of the Invention According to the present invention, there are no defects caused by peeling over a wide area (
It is possible to form a thin film EL element with uniform emission brightness from a low brightness region to a high brightness region with good reproducibility.

Therefore, it has great practical value, especially when forming a multicolor thin film EL element in which a luminance modulation function is essential.

[Brief explanation of the drawing]

FIG. 1 is a flowchart for explaining one embodiment of the present invention, FIG. 2 is a sectional view of a thin film EL device, and FIGS. 3 to 5 are sectional views of the thin film EL device during the manufacturing process. 1... Glass substrate, 2. ITO transparent electrode, 3...
- First insulator layer, 4.5.6... Light emitter layer, 7.8.
9... Photoresist, 10... Second insulator layer, 11
...Back electrode. Name of agent: Patent attorney Shigetaka Awano 1 person -m- -1- 4,5,6-・- Galaz I! Figure of transparent Denki IIe conductor layer light emitting layer?

Claims (5)

[Claims] (1) A method for manufacturing a multicolor thin film EL device in which a transparent electrode, an insulating layer, a light emitting layer in which two or more types of phosphor thin films are arranged on the same plane, electrodes, etc. are laminated on a transparent substrate. In forming the luminescent layer, forming a phosphor thin film,
A multicolor thin film EL characterized in that the entire surface of the substrate including the surface of the phosphor thin film is etched by etching the photoresist into an arbitrary pattern, removing the photoresist, and then irradiating accelerated ions or atoms. Method of manufacturing elements. (2) The method for manufacturing a multicolor thin film EL device according to claim 1, wherein the etching means using accelerated ions or atoms is an ion beam etching method. (3) The method for manufacturing a multicolor thin film EL device according to claim 1, wherein the etching means using accelerated ions or atoms is a sputter etching method using ions generated by plasma. (4) The etching depth of the phosphor thin film is 5 nm or more, 1
2. The method for manufacturing a multicolor thin film EL device according to claim 1, wherein the thickness is 00 nm or less. (5) The method for manufacturing a multicolor thin film EL device according to claim 1, wherein the ions or atoms used for etching the surface of the phosphor thin film consist of one or more of rare gases and oxygen.