JPH04192289A - Manufacture of electroluminescence element - Google Patents

Abstract

PURPOSE:To suppress thermal diffusion of the components between layers, to increase the luminous brightness of the element, to improve a voltage-resisting property, and to realize a long service life and a low cost, by maintaining the temperature of a substrate at 150 to 200 deg.C, and forming the layers by an ion beam spattering. CONSTITUTION:After a soda glass substrate 1 is cleaned and dried, it is set on a substrate holder 11 of a multi-beam spattering device. In the device, the targets of the materials to form layers are arranged, and the layers can be formed by only converting the radiation sources of ion beams. After the inside of a chamber is evacuated less than 2X10<-6> Torr, the asist ion beams are radiated on the substrate to maintain the heating at 150 to 200 deg.C. Then, by using an ion beam sputtering, a transparent electrode layer 2 of an ITO membrane, the first insulating layer 3 of Y2O3 a luminous substance layer 4 of ZnS.Mn, the second insulating layer 5 of Y2O3, and a transparent electrode layer 6 of an ITO membrane are formed in order to manufacture an electroluminescence element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an electroluminescent device that can be used as a light emitting display device.

[Conventional technology]

Conventionally, a transmission-type electroluminescent element has a substrate, a light-emitting layer, and an insulating layer disposed to sandwich the light-emitting layer from both sides between a pair of opposing transparent electrode layers. formed and configured on.

This electroluminescent element emits light from a light emitter layer by applying a voltage equal to or higher than a light emission threshold voltage between transparent electrodes. This light-emitting layer is used as a display device.

This method of manufacturing an electroluminescent device generally consists of forming each of the above-mentioned layers on a glass substrate heated to 250 to 350° C. using an ion blating method, an electron beam evaporation method, or an RF sputtering method. By the way, when a glass substrate is heated to 250 to 350°C to form a film as described above, Na, which is an alkaline component contained in the glass substrate, is removed.

K, Ca, etc., and indium and tin in the transparent electrode layer are easily thermally diffused into the insulating layer and the light emitting layer. These are insulating layers,
It becomes an impurity in the light-emitting layer and deteriorates the film quality, which originally has high insulation and light-emitting properties. The resulting electroluminescent device had low insulation, high leakage current, and the inability to apply a sufficient voltage to the light emitting layer, resulting in low luminance.

Further, if a voltage is applied forcibly, there is a problem that the electroluminescent element is destroyed due to heat generation due to leakage current.

Therefore, on the glass substrate on which the transparent electrode layer was formed, the insulating layer and the luminescent layer were heated at a low temperature (200°C) using the ion blasting method.
There is a disclosure of a method of forming a film by increasing the film forming rate (Japanese Patent Publication No. 63-29396).

[Problem to be solved by the invention]

However, with the above method, it is difficult to sufficiently suppress indium and tin from penetrating into the insulating layer due to thermal diffusion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electroluminescent element that prevents a decrease in luminance.

[Means for Solving the Problems] The method for manufacturing an electroluminescent device of the present invention includes sandwiching a light-emitting layer and a light-emitting layer from both sides between a pair of opposing transparent electrode layers and the transparent electrode layer. A method of manufacturing an electroluminescent device comprising an insulating layer disposed on a substrate, the method comprising forming each layer by ion beam sputtering while holding the substrate at a temperature of 150 to 200''C. It is characterized by

In this method for manufacturing an electroluminescent device, a transparent electrode layer, an insulating layer, a light emitter layer, an insulating layer, and a transparent electrode layer can be successively formed in this order within an ion beam sputtering apparatus. When forming a film using this method, a good film layer can be formed by keeping the temperature of the substrate in a low range of 150 to 200°C.

If the substrate temperature is less than 150° C., the luminance of the electroluminescent device will be low, which is not preferable. 20 again
If it exceeds 0°C, both the withstand voltage and luminance will decrease, which is not preferable.

The reason for this is that since the glass substrate is at a low temperature, alkali components in the substrate and indium and tin in the transparent electrode layer thermally diffuse into the insulating layer and the light emitting layer as impurities, suppressing deterioration in insulation properties and film quality. I can do it.

As a result, an electroluminescent element with high brightness and high withstand voltage can be manufactured.

In addition, unlike conventional methods, after the transparent electrode is formed using the ion blating method or RF sputtering method, another method such as electron beam evaporation or ion blating that can efficiently form the insulating layer and the luminescent layer is used. There is no need to form it with Therefore, the manufacturing process can be made more efficient.

[Effect]

According to the method for manufacturing an electroluminescent device of the present invention, each layer is sequentially formed on a glass substrate using an ion beam sputtering method. And the temperature of the board is 150-20
Each film layer is formed while maintaining the temperature at 0°C. Therefore, heating in the above range does not cause thermal diffusion and can prevent the glass components and transparent electrode components of the substrate from penetrating into the insulating layer and the light emitting layer as impurities. As a result, an electroluminescent device with high luminance can be obtained. Furthermore, inexpensive soda glass can be used as the glass substrate.

Furthermore, since each film layer can be formed using the same device, the manufacturing process can be simplified.

〔Example〕

This will be explained in detail below using examples.

As shown in FIG. 1, this electroluminescent element includes a glass substrate 1, an ITO film layer of a transparent electrode 2, and a first insulating layer 3.
Yttrium oxide film of , ZnS-Mn film of luminescent layer 4,
Yttrium oxide film of second insulating layer 5, IT of transparent electrode 6
It is formed by stacking an O film layer. The structure is such that an AC voltage is applied between the transparent electrodes to emit light.

(Example 1) Production of electroluminescent device After cleaning and drying a soda glass substrate with a thickness of 1.1 mm, a multi-ion beam sputtering apparatus (Nl1-250T-A type manufactured by Nissin Electric Co., Ltd.) shown in FIG. 2 was used. (hereinafter referred to as MIBS method).

Three types of targets for forming the transparent electrode layer, the insulating layer, and the luminescent layer are arranged inside the device, and each film layer can be formed by changing the ion beam irradiation source. The substrate is irradiated with an assist ion beam. The inside of the device is a vacuum chamber.

After evacuating the inside of the chamber of the apparatus to below 2×10 −@Torr, the substrate 1 is heated to 150 to 200° C. In addition,
The substrate temperature is kept constant during film formation.

After heating the substrate, use ion beam sputtering to create a JTO with a thickness of 2,000 people! i transparent electrode layer 2, thickness 4000 Y2O,
A first insulating layer 3 of ZnS-Mn with a thickness of 6000, a second insulating layer 5 of Y2O3 with a thickness of 4000, and a transparent electrode layer 6 of ITO with a thickness of 2000 are sequentially formed. An electroluminescent device (a) having the structure shown in FIG. 1 was prepared.

In addition, as an ion beam for sputtering, the ion energy is IKeV ~ 1.5KeV, and the ion current is 70mA ~ 1
00 mA of argon ion was used.

(Comparative example 1) The temperature of the substrate was set to 100°C (b) using the method of the example.

An electroluminescent device was produced in the same manner except that 250(c) was used.

(Comparative Example 2) A soda glass substrate treated in the same manner as in the example was set in an ion blating device.

The substrate 1 was heated to 300° C., and a transparent electrode layer 2 of 2000 layers of ITO was formed by ion plating.

Subsequently, on this transparent electrode film 2, Y2O of 4000 nm thick was deposited on a substrate heated to 300°C by electron beam evaporation.
A first insulating layer 3 of 6,000 thick, a phosphor layer 4 of ZnS-Mn with a thickness of 6000, and a second insulating layer 5 of Y2O3 with a thickness of 4000.

Furthermore, the substrate was heated to 300° C. on top of the insulating layer 5, and a transparent electrode layer 6 of ITO having a thickness of 2000 layers was formed by ion plating to produce an electroluminescent device (d).

For the electroluminescent elements produced in the evaluation examples and comparative examples, an alternating current voltage of 5 KHz was applied between both electrodes, and the emission brightness-voltage characteristics were measured.

The results are shown in Figure 3.

(a), where the film was formed at a substrate temperature of 150 to 200°C, has the highest luminance (140V, 275cd/m); at a temperature lower than that, 100°C, the withstand voltage of the device (b) improves, but no light is emitted. Brightness is low. Further, the element (c) formed at a temperature higher than 200° C. has low withstand voltage and low luminance. This is considered to be because when the substrate temperature is low, the film quality of the materials constituting the electroluminescent element, especially the ZnS-Mn luminescent layer, deteriorates. On the other hand, when the substrate temperature is high, it is thought that this is because impurity diffusion increases.

When the film was formed using the ion blating method of Comparative Example 2,
The electroluminescent device fabricated at a substrate temperature of 300 to 350°C had the highest luminance (80V,
30 c d/if).

Therefore, when the film was formed using the ion beam sputtering method at a substrate temperature in the range of 150 to 200° C., the luminance was improved by about 10 times compared to the device formed by the conventional method.

〔effect〕

In this method, the film can be formed while keeping the temperature of the substrate low, so thermal diffusion of components between layers can be suppressed. As a result, the luminance of the device increases, the withstand voltage also improves, and the lifetime of the device increases.

Furthermore, since elements manufactured in this temperature range have substantially constant characteristic values such as threshold voltage, luminance, and dielectric breakdown voltage, temperature control during manufacturing becomes easy.

Since the substrate temperature is low, diffusion of alkaline components is suppressed and soda glass can be used as the substrate. Therefore, it is possible to reduce costs.

Further, since all the films can be formed by the MIBS method, the process can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional diagram showing the structure of an electroluminescent device, Fig. 2 is a schematic explanatory diagram of a multi-ion beam sputtering device, and Fig. 3 is a line graph showing the relationship between applied voltage of the device and luminance. . 1...Glass substrate 2.6...Transparent electrode 3...
・First insulating layer 4... Luminous layer 5... Second insulating layer Patent applicant Toyota Motor Corporation

Claims (1)

[Claims] A luminescent layer and an insulating layer disposed to sandwich the luminescent layer from both sides are formed on a substrate between a pair of opposing transparent electrode layers and the transparent electrode layer. 1. A method for manufacturing an electroluminescent device comprising the steps of: maintaining a substrate at a temperature of 150 to 200° C. and forming each layer by ion beam sputtering.